From aecca0676ddd9e032de4eeda371b81598d3257bb Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 8 Sep 2025 12:49:37 +0200 Subject: rust: use inline const expressions They were stabilized in Rust 1.79.0. Reviewed-by: Zhao Liu Link: https://lore.kernel.org/r/20250908105005.2119297-6-pbonzini@redhat.com Signed-off-by: Paolo Bonzini --- rust/qemu-api/src/chardev.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/qemu-api/src/chardev.rs') diff --git a/rust/qemu-api/src/chardev.rs b/rust/qemu-api/src/chardev.rs index 6e0590d758..cb27be5256 100644 --- a/rust/qemu-api/src/chardev.rs +++ b/rust/qemu-api/src/chardev.rs @@ -138,7 +138,7 @@ impl CharBackend { F::call((owner, event)) } - let _: () = CanReceiveFn::ASSERT_IS_SOME; + const { assert!(CanReceiveFn::IS_SOME) }; let receive_cb: Option = if ReceiveFn::is_some() { Some(rust_receive_cb::) -- cgit 1.4.1 From 593c408a6a8cd8b0af9bf60c7c3625da7910a737 Mon Sep 17 00:00:00 2001 From: Marc-André Lureau Date: Mon, 8 Sep 2025 12:49:48 +0200 Subject: rust: split Rust-only "common" crate MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Marc-André Lureau Link: https://lore.kernel.org/r/20250827104147.717203-6-marcandre.lureau@redhat.com Reviewed-by: Zhao Liu Signed-off-by: Paolo Bonzini --- MAINTAINERS | 1 + rust/Cargo.lock | 10 + rust/Cargo.toml | 1 + rust/common/Cargo.toml | 19 ++ rust/common/meson.build | 34 ++++ rust/common/src/assertions.rs | 148 +++++++++++++++ rust/common/src/bitops.rs | 118 ++++++++++++ rust/common/src/callbacks.rs | 216 +++++++++++++++++++++ rust/common/src/errno.rs | 354 +++++++++++++++++++++++++++++++++++ rust/common/src/lib.rs | 20 ++ rust/common/src/opaque.rs | 238 +++++++++++++++++++++++ rust/common/src/uninit.rs | 85 +++++++++ rust/common/src/zeroable.rs | 18 ++ rust/hw/char/pl011/Cargo.toml | 1 + rust/hw/char/pl011/meson.build | 3 +- rust/hw/char/pl011/src/device.rs | 3 +- rust/hw/timer/hpet/Cargo.toml | 1 + rust/hw/timer/hpet/meson.build | 3 +- rust/hw/timer/hpet/src/device.rs | 2 +- rust/hw/timer/hpet/src/fw_cfg.rs | 3 +- rust/meson.build | 1 + rust/qemu-api-macros/src/lib.rs | 16 +- rust/qemu-api-macros/src/tests.rs | 6 +- rust/qemu-api/Cargo.toml | 1 + rust/qemu-api/meson.build | 14 +- rust/qemu-api/src/assertions.rs | 148 --------------- rust/qemu-api/src/bindings.rs | 21 +++ rust/qemu-api/src/bitops.rs | 119 ------------ rust/qemu-api/src/callbacks.rs | 216 --------------------- rust/qemu-api/src/cell.rs | 235 +---------------------- rust/qemu-api/src/chardev.rs | 5 +- rust/qemu-api/src/errno.rs | 354 ----------------------------------- rust/qemu-api/src/error.rs | 3 +- rust/qemu-api/src/irq.rs | 3 +- rust/qemu-api/src/lib.rs | 6 - rust/qemu-api/src/log.rs | 4 +- rust/qemu-api/src/memory.rs | 5 +- rust/qemu-api/src/prelude.rs | 6 +- rust/qemu-api/src/qdev.rs | 10 +- rust/qemu-api/src/qom.rs | 3 +- rust/qemu-api/src/sysbus.rs | 3 +- rust/qemu-api/src/timer.rs | 8 +- rust/qemu-api/src/uninit.rs | 85 --------- rust/qemu-api/src/vmstate.rs | 23 +-- rust/qemu-api/src/zeroable.rs | 37 ---- rust/qemu-api/tests/vmstate_tests.rs | 3 +- 46 files changed, 1351 insertions(+), 1262 deletions(-) create mode 100644 rust/common/Cargo.toml create mode 100644 rust/common/meson.build create mode 100644 rust/common/src/assertions.rs create mode 100644 rust/common/src/bitops.rs create mode 100644 rust/common/src/callbacks.rs create mode 100644 rust/common/src/errno.rs create mode 100644 rust/common/src/lib.rs create mode 100644 rust/common/src/opaque.rs create mode 100644 rust/common/src/uninit.rs create mode 100644 rust/common/src/zeroable.rs delete mode 100644 rust/qemu-api/src/assertions.rs delete mode 100644 rust/qemu-api/src/bitops.rs delete mode 100644 rust/qemu-api/src/callbacks.rs delete mode 100644 rust/qemu-api/src/errno.rs delete mode 100644 rust/qemu-api/src/uninit.rs delete mode 100644 rust/qemu-api/src/zeroable.rs (limited to 'rust/qemu-api/src/chardev.rs') diff --git a/MAINTAINERS b/MAINTAINERS index fb045388b9..cee5a34206 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3515,6 +3515,7 @@ F: include/hw/registerfields.h Rust M: Manos Pitsidianakis S: Maintained +F: rust/common/ F: rust/qemu-api F: rust/qemu-api-macros F: rust/rustfmt.toml diff --git a/rust/Cargo.lock b/rust/Cargo.lock index 4baf6ba663..71e8c7ed62 100644 --- a/rust/Cargo.lock +++ b/rust/Cargo.lock @@ -44,6 +44,13 @@ dependencies = [ "qemu_api_macros", ] +[[package]] +name = "common" +version = "0.1.0" +dependencies = [ + "libc", +] + [[package]] name = "either" version = "1.12.0" @@ -63,6 +70,7 @@ dependencies = [ name = "hpet" version = "0.1.0" dependencies = [ + "common", "qemu_api", "qemu_api_macros", ] @@ -89,6 +97,7 @@ dependencies = [ "bilge", "bilge-impl", "bits", + "common", "qemu_api", "qemu_api_macros", ] @@ -130,6 +139,7 @@ name = "qemu_api" version = "0.1.0" dependencies = [ "anyhow", + "common", "foreign", "libc", "qemu_api_macros", diff --git a/rust/Cargo.toml b/rust/Cargo.toml index cd4bf8ef8e..c0426d4243 100644 --- a/rust/Cargo.toml +++ b/rust/Cargo.toml @@ -2,6 +2,7 @@ resolver = "2" members = [ "bits", + "common", "qemu-api-macros", "qemu-api", "hw/char/pl011", diff --git a/rust/common/Cargo.toml b/rust/common/Cargo.toml new file mode 100644 index 0000000000..5e106427e8 --- /dev/null +++ b/rust/common/Cargo.toml @@ -0,0 +1,19 @@ +[package] +name = "common" +version = "0.1.0" +description = "Rust common code for QEMU" +resolver = "2" +publish = false + +authors.workspace = true +edition.workspace = true +homepage.workspace = true +license.workspace = true +repository.workspace = true +rust-version.workspace = true + +[dependencies] +libc.workspace = true + +[lints] +workspace = true diff --git a/rust/common/meson.build b/rust/common/meson.build new file mode 100644 index 0000000000..230a967760 --- /dev/null +++ b/rust/common/meson.build @@ -0,0 +1,34 @@ +_common_cfg = run_command(rustc_args, + '--config-headers', config_host_h, '--features', files('Cargo.toml'), + capture: true, check: true).stdout().strip().splitlines() + +_common_rs = static_library( + 'common', + structured_sources( + [ + 'src/lib.rs', + 'src/assertions.rs', + 'src/bitops.rs', + 'src/callbacks.rs', + 'src/errno.rs', + 'src/opaque.rs', + 'src/uninit.rs', + 'src/zeroable.rs', + ], + ), + override_options: ['rust_std=2021', 'build.rust_std=2021'], + rust_abi: 'rust', + rust_args: _common_cfg, + dependencies: [libc_rs], +) + +common_rs = declare_dependency(link_with: [_common_rs]) + +# Doctests are essentially integration tests, so they need the same dependencies. +# Note that running them requires the object files for C code, so place them +# in a separate suite that is run by the "build" CI jobs rather than "check". +rust.doctest('rust-common-doctests', + _common_rs, + protocol: 'rust', + dependencies: common_rs, + suite: ['doc', 'rust']) diff --git a/rust/common/src/assertions.rs b/rust/common/src/assertions.rs new file mode 100644 index 0000000000..91f83a5d3d --- /dev/null +++ b/rust/common/src/assertions.rs @@ -0,0 +1,148 @@ +// Copyright 2024, Red Hat Inc. +// Author(s): Paolo Bonzini +// SPDX-License-Identifier: GPL-2.0-or-later + +#![doc(hidden)] +//! This module provides macros to check the equality of types and +//! the type of `struct` fields. This can be useful to ensure that +//! types match the expectations of C code. +//! +//! Documentation is hidden because it only exposes macros, which +//! are exported directly from `common`. + +// Based on https://stackoverflow.com/questions/64251852/x/70978292#70978292 +// (stackoverflow answers are released under MIT license). + +#[doc(hidden)] +pub trait EqType { + type Itself; +} + +impl EqType for T { + type Itself = T; +} + +/// Assert that two types are the same. +/// +/// # Examples +/// +/// ``` +/// # use common::assert_same_type; +/// # use std::ops::Deref; +/// assert_same_type!(u32, u32); +/// assert_same_type!( as Deref>::Target, u32); +/// ``` +/// +/// Different types will cause a compile failure +/// +/// ```compile_fail +/// # use common::assert_same_type; +/// assert_same_type!(&Box, &u32); +/// ``` +#[macro_export] +macro_rules! assert_same_type { + ($t1:ty, $t2:ty) => { + const _: () = { + #[allow(unused)] + fn assert_same_type(v: $t1) { + fn types_must_be_equal(_: T) + where + T: $crate::assertions::EqType, + { + } + types_must_be_equal::<_, $t2>(v); + } + }; + }; +} + +/// Assert that a field of a struct has the given type. +/// +/// # Examples +/// +/// ``` +/// # use common::assert_field_type; +/// pub struct A { +/// field1: u32, +/// } +/// +/// assert_field_type!(A, field1, u32); +/// ``` +/// +/// Different types will cause a compile failure +/// +/// ```compile_fail +/// # use common::assert_field_type; +/// # pub struct A { field1: u32 } +/// assert_field_type!(A, field1, i32); +/// ``` +#[macro_export] +macro_rules! assert_field_type { + (@internal $param_name:ident, $ti:ty, $t:ty, $($field:tt)*) => { + const _: () = { + #[allow(unused)] + const fn assert_field_type($param_name: &$t) { + const fn types_must_be_equal(_: &T) + where + T: $crate::assertions::EqType, + { + } + types_must_be_equal::<_, $ti>(&$($field)*); + } + }; + }; + + ($t:ty, $i:tt, $ti:ty) => { + $crate::assert_field_type!(@internal v, $ti, $t, v.$i); + }; +} + +/// Assert that an expression matches a pattern. This can also be +/// useful to compare enums that do not implement `Eq`. +/// +/// # Examples +/// +/// ``` +/// # use common::assert_match; +/// // JoinHandle does not implement `Eq`, therefore the result +/// // does not either. +/// let result: Result, u32> = Err(42); +/// assert_match!(result, Err(42)); +/// ``` +#[macro_export] +macro_rules! assert_match { + ($a:expr, $b:pat) => { + assert!( + match $a { + $b => true, + _ => false, + }, + "{} = {:?} does not match {}", + stringify!($a), + $a, + stringify!($b) + ); + }; +} + +/// Assert at compile time that an expression is true. This is similar +/// to `const { assert!(...); }` but it works outside functions, as well as +/// on versions of Rust before 1.79. +/// +/// # Examples +/// +/// ``` +/// # use common::static_assert; +/// static_assert!("abc".len() == 3); +/// ``` +/// +/// ```compile_fail +/// # use common::static_assert; +/// static_assert!("abc".len() == 2); // does not compile +/// ``` +#[macro_export] +macro_rules! static_assert { + ($x:expr) => { + const _: () = assert!($x); + }; +} diff --git a/rust/common/src/bitops.rs b/rust/common/src/bitops.rs new file mode 100644 index 0000000000..06c78c3b8a --- /dev/null +++ b/rust/common/src/bitops.rs @@ -0,0 +1,118 @@ +// Copyright (C) 2024 Intel Corporation. +// Author(s): Zhao Liu +// SPDX-License-Identifier: GPL-2.0-or-later + +//! This module provides bit operation extensions to integer types. + +use std::ops::{ + Add, AddAssign, BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Div, DivAssign, + Mul, MulAssign, Not, Rem, RemAssign, Shl, ShlAssign, Shr, ShrAssign, +}; + +/// Trait for extensions to integer types +pub trait IntegerExt: + Add + AddAssign + + BitAnd + BitAndAssign + + BitOr + BitOrAssign + + BitXor + BitXorAssign + + Copy + + Div + DivAssign + + Eq + + Mul + MulAssign + + Not + Ord + PartialOrd + + Rem + RemAssign + + Shl + ShlAssign + + Shl + ShlAssign + // add more as needed + Shr + ShrAssign + + Shr + ShrAssign // add more as needed +{ + const BITS: u32; + const MAX: Self; + const MIN: Self; + const ONE: Self; + const ZERO: Self; + + #[inline] + #[must_use] + fn bit(start: u32) -> Self + { + debug_assert!(start < Self::BITS); + + Self::ONE << start + } + + #[inline] + #[must_use] + fn mask(start: u32, length: u32) -> Self + { + /* FIXME: Implement a more elegant check with error handling support? */ + debug_assert!(start < Self::BITS && length > 0 && length <= Self::BITS - start); + + (Self::MAX >> (Self::BITS - length)) << start + } + + #[inline] + #[must_use] + fn deposit(self, start: u32, length: u32, + fieldval: U) -> Self + where Self: From + { + debug_assert!(length <= U::BITS); + + let mask = Self::mask(start, length); + (self & !mask) | ((Self::from(fieldval) << start) & mask) + } + + #[inline] + #[must_use] + fn extract(self, start: u32, length: u32) -> Self + { + let mask = Self::mask(start, length); + (self & mask) >> start + } +} + +macro_rules! impl_num_ext { + ($type:ty) => { + impl IntegerExt for $type { + const BITS: u32 = <$type>::BITS; + const MAX: Self = <$type>::MAX; + const MIN: Self = <$type>::MIN; + const ONE: Self = 1; + const ZERO: Self = 0; + } + }; +} + +impl_num_ext!(u8); +impl_num_ext!(u16); +impl_num_ext!(u32); +impl_num_ext!(u64); + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_deposit() { + assert_eq!(15u32.deposit(8, 8, 1u32), 256 + 15); + assert_eq!(15u32.deposit(8, 1, 255u8), 256 + 15); + } + + #[test] + fn test_extract() { + assert_eq!(15u32.extract(2, 4), 3); + } + + #[test] + fn test_bit() { + assert_eq!(u8::bit(7), 128); + assert_eq!(u32::bit(16), 0x10000); + } + + #[test] + fn test_mask() { + assert_eq!(u8::mask(7, 1), 128); + assert_eq!(u32::mask(8, 8), 0xff00); + } +} diff --git a/rust/common/src/callbacks.rs b/rust/common/src/callbacks.rs new file mode 100644 index 0000000000..b8898fe96f --- /dev/null +++ b/rust/common/src/callbacks.rs @@ -0,0 +1,216 @@ +// SPDX-License-Identifier: MIT + +//! Utility functions to deal with callbacks from C to Rust. + +use std::{mem, ptr::NonNull}; + +/// Trait for functions (types implementing [`Fn`]) that can be used as +/// callbacks. These include both zero-capture closures and function pointers. +/// +/// In Rust, calling a function through the `Fn` trait normally requires a +/// `self` parameter, even though for zero-sized functions (including function +/// pointers) the type itself contains all necessary information to call the +/// function. This trait provides a `call` function that doesn't require `self`, +/// allowing zero-sized functions to be called using only their type. +/// +/// This enables zero-sized functions to be passed entirely through generic +/// parameters and resolved at compile-time. A typical use is a function +/// receiving an unused parameter of generic type `F` and calling it via +/// `F::call` or passing it to another function via `func::`. +/// +/// QEMU uses this trick to create wrappers to C callbacks. The wrappers +/// are needed to convert an opaque `*mut c_void` into a Rust reference, +/// but they only have a single opaque that they can use. The `FnCall` +/// trait makes it possible to use that opaque for `self` or any other +/// reference: +/// +/// ```ignore +/// // The compiler creates a new `rust_bh_cb` wrapper for each function +/// // passed to `qemu_bh_schedule_oneshot` below. +/// unsafe extern "C" fn rust_bh_cb FnCall<(&'a T,)>>( +/// opaque: *mut c_void, +/// ) { +/// // SAFETY: the opaque was passed as a reference to `T`. +/// F::call((unsafe { &*(opaque.cast::()) }, )) +/// } +/// +/// // The `_f` parameter is unused but it helps the compiler build the appropriate `F`. +/// // Using a reference allows usage in const context. +/// fn qemu_bh_schedule_oneshot FnCall<(&'a T,)>>(_f: &F, opaque: &T) { +/// let cb: unsafe extern "C" fn(*mut c_void) = rust_bh_cb::; +/// unsafe { +/// bindings::qemu_bh_schedule_oneshot(cb, opaque as *const T as *const c_void as *mut c_void) +/// } +/// } +/// ``` +/// +/// Each wrapper is a separate instance of `rust_bh_cb` and is therefore +/// compiled to a separate function ("monomorphization"). If you wanted +/// to pass `self` as the opaque value, the generic parameters would be +/// `rust_bh_cb::`. +/// +/// `Args` is a tuple type whose types are the arguments of the function, +/// while `R` is the returned type. +/// +/// # Examples +/// +/// ``` +/// # use common::callbacks::FnCall; +/// fn call_it FnCall<(&'a str,), String>>(_f: &F, s: &str) -> String { +/// F::call((s,)) +/// } +/// +/// let s: String = call_it(&str::to_owned, "hello world"); +/// assert_eq!(s, "hello world"); +/// ``` +/// +/// Note that the compiler will produce a different version of `call_it` for +/// each function that is passed to it. Therefore the argument is not really +/// used, except to decide what is `F` and what `F::call` does. +/// +/// Attempting to pass a non-zero-sized closure causes a compile-time failure: +/// +/// ```compile_fail +/// # use common::callbacks::FnCall; +/// # fn call_it<'a, F: FnCall<(&'a str,), String>>(_f: &F, s: &'a str) -> String { +/// # F::call((s,)) +/// # } +/// let x: &'static str = "goodbye world"; +/// call_it(&move |_| String::from(x), "hello workd"); +/// ``` +/// +/// `()` can be used to indicate "no function": +/// +/// ``` +/// # use common::callbacks::FnCall; +/// fn optional FnCall<(&'a str,), String>>(_f: &F, s: &str) -> Option { +/// if F::IS_SOME { +/// Some(F::call((s,))) +/// } else { +/// None +/// } +/// } +/// +/// assert!(optional(&(), "hello world").is_none()); +/// ``` +/// +/// Invoking `F::call` will then be a run-time error. +/// +/// ```should_panic +/// # use common::callbacks::FnCall; +/// # fn call_it FnCall<(&'a str,), String>>(_f: &F, s: &str) -> String { +/// # F::call((s,)) +/// # } +/// let s: String = call_it(&(), "hello world"); // panics +/// ``` +/// +/// # Safety +/// +/// Because `Self` is a zero-sized type, all instances of the type are +/// equivalent. However, in addition to this, `Self` must have no invariants +/// that could be violated by creating a reference to it. +/// +/// This is always true for zero-capture closures and function pointers, as long +/// as the code is able to name the function in the first place. +pub unsafe trait FnCall: 'static + Sync + Sized { + /// `true` if `Self` is an actual function type and not `()`. + /// + /// # Examples + /// + /// You can use `IS_SOME` to catch this at compile time: + /// + /// ```compile_fail + /// # use common::callbacks::FnCall; + /// fn call_it FnCall<(&'a str,), String>>(_f: &F, s: &str) -> String { + /// const { assert!(F::IS_SOME) } + /// F::call((s,)) + /// } + /// + /// let s: String = call_it((), "hello world"); // does not compile + /// ``` + const IS_SOME: bool; + + /// `false` if `Self` is an actual function type, `true` if it is `()`. + fn is_none() -> bool { + !Self::IS_SOME + } + + /// `true` if `Self` is an actual function type, `false` if it is `()`. + fn is_some() -> bool { + Self::IS_SOME + } + + /// Call the function with the arguments in args. + fn call(a: Args) -> R; +} + +/// `()` acts as a "null" callback. Using `()` and `function` is nicer +/// than `None` and `Some(function)`, because the compiler is unable to +/// infer the type of just `None`. Therefore, the trait itself acts as the +/// option type, with functions [`FnCall::is_some`] and [`FnCall::is_none`]. +unsafe impl FnCall for () { + const IS_SOME: bool = false; + + /// Call the function with the arguments in args. + fn call(_a: Args) -> R { + panic!("callback not specified") + } +} + +macro_rules! impl_call { + ($($args:ident,)* ) => ( + // SAFETY: because each function is treated as a separate type, + // accessing `FnCall` is only possible in code that would be + // allowed to call the function. + unsafe impl FnCall<($($args,)*), R> for F + where + F: 'static + Sync + Sized + Fn($($args, )*) -> R, + { + const IS_SOME: bool = true; + + #[inline(always)] + fn call(a: ($($args,)*)) -> R { + const { assert!(mem::size_of::() == 0) }; + + // SAFETY: the safety of this method is the condition for implementing + // `FnCall`. As to the `NonNull` idiom to create a zero-sized type, + // see https://github.com/rust-lang/libs-team/issues/292. + let f: &'static F = unsafe { &*NonNull::::dangling().as_ptr() }; + let ($($args,)*) = a; + f($($args,)*) + } + } + ) +} + +impl_call!(_1, _2, _3, _4, _5,); +impl_call!(_1, _2, _3, _4,); +impl_call!(_1, _2, _3,); +impl_call!(_1, _2,); +impl_call!(_1,); +impl_call!(); + +#[cfg(test)] +mod tests { + use super::*; + + // The `_f` parameter is unused but it helps the compiler infer `F`. + fn do_test_call<'a, F: FnCall<(&'a str,), String>>(_f: &F) -> String { + F::call(("hello world",)) + } + + #[test] + fn test_call() { + assert_eq!(do_test_call(&str::to_owned), "hello world") + } + + // The `_f` parameter is unused but it helps the compiler infer `F`. + fn do_test_is_some<'a, F: FnCall<(&'a str,), String>>(_f: &F) { + assert!(F::is_some()); + } + + #[test] + fn test_is_some() { + do_test_is_some(&str::to_owned); + } +} diff --git a/rust/common/src/errno.rs b/rust/common/src/errno.rs new file mode 100644 index 0000000000..64b2933b07 --- /dev/null +++ b/rust/common/src/errno.rs @@ -0,0 +1,354 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +//! Utility functions to convert `errno` to and from +//! [`io::Error`]/[`io::Result`] +//! +//! QEMU C functions often have a "positive success/negative `errno`" calling +//! convention. This module provides functions to portably convert an integer +//! into an [`io::Result`] and back. + +use std::{ + convert::{self, TryFrom}, + io::{self, ErrorKind}, +}; + +/// An `errno` value that can be converted into an [`io::Error`] +pub struct Errno(pub u16); + +// On Unix, from_raw_os_error takes an errno value and OS errors +// are printed using strerror. On Windows however it takes a +// GetLastError() value; therefore we need to convert errno values +// into io::Error by hand. This is the same mapping that the +// standard library uses to retrieve the kind of OS errors +// (`std::sys::pal::unix::decode_error_kind`). +impl From for ErrorKind { + fn from(value: Errno) -> ErrorKind { + use ErrorKind::*; + let Errno(errno) = value; + match i32::from(errno) { + libc::EPERM | libc::EACCES => PermissionDenied, + libc::ENOENT => NotFound, + libc::EINTR => Interrupted, + x if x == libc::EAGAIN || x == libc::EWOULDBLOCK => WouldBlock, + libc::ENOMEM => OutOfMemory, + libc::EEXIST => AlreadyExists, + libc::EINVAL => InvalidInput, + libc::EPIPE => BrokenPipe, + libc::EADDRINUSE => AddrInUse, + libc::EADDRNOTAVAIL => AddrNotAvailable, + libc::ECONNABORTED => ConnectionAborted, + libc::ECONNREFUSED => ConnectionRefused, + libc::ECONNRESET => ConnectionReset, + libc::ENOTCONN => NotConnected, + libc::ENOTSUP => Unsupported, + libc::ETIMEDOUT => TimedOut, + _ => Other, + } + } +} + +// This is used on Windows for all io::Errors, but also on Unix if the +// io::Error does not have a raw OS error. This is the reversed +// mapping of the above; EIO is returned for unknown ErrorKinds. +impl From for Errno { + fn from(value: io::ErrorKind) -> Errno { + use ErrorKind::*; + let errno = match value { + // can be both EPERM or EACCES :( pick one + PermissionDenied => libc::EPERM, + NotFound => libc::ENOENT, + Interrupted => libc::EINTR, + WouldBlock => libc::EAGAIN, + OutOfMemory => libc::ENOMEM, + AlreadyExists => libc::EEXIST, + InvalidInput => libc::EINVAL, + BrokenPipe => libc::EPIPE, + AddrInUse => libc::EADDRINUSE, + AddrNotAvailable => libc::EADDRNOTAVAIL, + ConnectionAborted => libc::ECONNABORTED, + ConnectionRefused => libc::ECONNREFUSED, + ConnectionReset => libc::ECONNRESET, + NotConnected => libc::ENOTCONN, + Unsupported => libc::ENOTSUP, + TimedOut => libc::ETIMEDOUT, + _ => libc::EIO, + }; + Errno(errno as u16) + } +} + +impl From for io::Error { + #[cfg(unix)] + fn from(value: Errno) -> io::Error { + let Errno(errno) = value; + io::Error::from_raw_os_error(errno.into()) + } + + #[cfg(windows)] + fn from(value: Errno) -> io::Error { + let error_kind: ErrorKind = value.into(); + error_kind.into() + } +} + +impl From for Errno { + fn from(value: io::Error) -> Errno { + if cfg!(unix) { + if let Some(errno) = value.raw_os_error() { + return Errno(u16::try_from(errno).unwrap()); + } + } + value.kind().into() + } +} + +impl From for Errno { + fn from(_value: convert::Infallible) -> Errno { + panic!("unreachable") + } +} + +/// Internal traits; used to enable [`into_io_result`] and [`into_neg_errno`] +/// for the "right" set of types. +mod traits { + use super::Errno; + + /// A signed type that can be converted into an + /// [`io::Result`](std::io::Result) + pub trait GetErrno { + /// Unsigned variant of `Self`, used as the type for the `Ok` case. + type Out; + + /// Return `Ok(self)` if positive, `Err(Errno(-self))` if negative + fn into_errno_result(self) -> Result; + } + + /// A type that can be taken out of an [`io::Result`](std::io::Result) and + /// converted into "positive success/negative `errno`" convention. + pub trait MergeErrno { + /// Signed variant of `Self`, used as the return type of + /// [`into_neg_errno`](super::into_neg_errno). + type Out: From + std::ops::Neg; + + /// Return `self`, asserting that it is in range + fn map_ok(self) -> Self::Out; + } + + macro_rules! get_errno { + ($t:ty, $out:ty) => { + impl GetErrno for $t { + type Out = $out; + fn into_errno_result(self) -> Result { + match self { + 0.. => Ok(self as $out), + -65535..=-1 => Err(Errno(-self as u16)), + _ => panic!("{self} is not a negative errno"), + } + } + } + }; + } + + get_errno!(i32, u32); + get_errno!(i64, u64); + get_errno!(isize, usize); + + macro_rules! merge_errno { + ($t:ty, $out:ty) => { + impl MergeErrno for $t { + type Out = $out; + fn map_ok(self) -> Self::Out { + self.try_into().unwrap() + } + } + }; + } + + merge_errno!(u8, i32); + merge_errno!(u16, i32); + merge_errno!(u32, i32); + merge_errno!(u64, i64); + + impl MergeErrno for () { + type Out = i32; + fn map_ok(self) -> i32 { + 0 + } + } +} + +use traits::{GetErrno, MergeErrno}; + +/// Convert an integer value into a [`io::Result`]. +/// +/// Positive values are turned into an `Ok` result; negative values +/// are interpreted as negated `errno` and turned into an `Err`. +/// +/// ``` +/// # use common::errno::into_io_result; +/// # use std::io::ErrorKind; +/// let ok = into_io_result(1i32).unwrap(); +/// assert_eq!(ok, 1u32); +/// +/// let err = into_io_result(-1i32).unwrap_err(); // -EPERM +/// assert_eq!(err.kind(), ErrorKind::PermissionDenied); +/// ``` +/// +/// # Panics +/// +/// Since the result is an unsigned integer, negative values must +/// be close to 0; values that are too far away are considered +/// likely overflows and will panic: +/// +/// ```should_panic +/// # use common::errno::into_io_result; +/// # #[allow(dead_code)] +/// let err = into_io_result(-0x1234_5678i32); // panic +/// ``` +pub fn into_io_result(value: T) -> io::Result { + value.into_errno_result().map_err(Into::into) +} + +/// Convert a [`Result`] into an integer value, using negative `errno` +/// values to report errors. +/// +/// ``` +/// # use common::errno::into_neg_errno; +/// # use std::io::{self, ErrorKind}; +/// let ok: io::Result<()> = Ok(()); +/// assert_eq!(into_neg_errno(ok), 0); +/// +/// let err: io::Result<()> = Err(ErrorKind::InvalidInput.into()); +/// assert_eq!(into_neg_errno(err), -22); // -EINVAL +/// ``` +/// +/// Since this module also provides the ability to convert [`io::Error`] +/// to an `errno` value, [`io::Result`] is the most commonly used type +/// for the argument of this function: +/// +/// # Panics +/// +/// Since the result is a signed integer, integer `Ok` values must remain +/// positive: +/// +/// ```should_panic +/// # use common::errno::into_neg_errno; +/// # use std::io; +/// let err: io::Result = Ok(0x8899_AABB); +/// into_neg_errno(err) // panic +/// # ; +/// ``` +pub fn into_neg_errno>(value: Result) -> T::Out { + match value { + Ok(x) => x.map_ok(), + Err(err) => -T::Out::from(err.into().0), + } +} + +#[cfg(test)] +mod tests { + use std::io::ErrorKind; + + use super::*; + use crate::assert_match; + + #[test] + pub fn test_from_u8() { + let ok: io::Result<_> = Ok(42u8); + assert_eq!(into_neg_errno(ok), 42); + + let err: io::Result = Err(io::ErrorKind::PermissionDenied.into()); + assert_eq!(into_neg_errno(err), -1); + + if cfg!(unix) { + let os_err: io::Result = Err(io::Error::from_raw_os_error(10)); + assert_eq!(into_neg_errno(os_err), -10); + } + } + + #[test] + pub fn test_from_u16() { + let ok: io::Result<_> = Ok(1234u16); + assert_eq!(into_neg_errno(ok), 1234); + + let err: io::Result = Err(io::ErrorKind::PermissionDenied.into()); + assert_eq!(into_neg_errno(err), -1); + + if cfg!(unix) { + let os_err: io::Result = Err(io::Error::from_raw_os_error(10)); + assert_eq!(into_neg_errno(os_err), -10); + } + } + + #[test] + pub fn test_i32() { + assert_match!(into_io_result(1234i32), Ok(1234)); + + let err = into_io_result(-1i32).unwrap_err(); + #[cfg(unix)] + assert_match!(err.raw_os_error(), Some(1)); + assert_match!(err.kind(), ErrorKind::PermissionDenied); + } + + #[test] + pub fn test_from_u32() { + let ok: io::Result<_> = Ok(1234u32); + assert_eq!(into_neg_errno(ok), 1234); + + let err: io::Result = Err(io::ErrorKind::PermissionDenied.into()); + assert_eq!(into_neg_errno(err), -1); + + if cfg!(unix) { + let os_err: io::Result = Err(io::Error::from_raw_os_error(10)); + assert_eq!(into_neg_errno(os_err), -10); + } + } + + #[test] + pub fn test_i64() { + assert_match!(into_io_result(1234i64), Ok(1234)); + + let err = into_io_result(-22i64).unwrap_err(); + #[cfg(unix)] + assert_match!(err.raw_os_error(), Some(22)); + assert_match!(err.kind(), ErrorKind::InvalidInput); + } + + #[test] + pub fn test_from_u64() { + let ok: io::Result<_> = Ok(1234u64); + assert_eq!(into_neg_errno(ok), 1234); + + let err: io::Result = Err(io::ErrorKind::InvalidInput.into()); + assert_eq!(into_neg_errno(err), -22); + + if cfg!(unix) { + let os_err: io::Result = Err(io::Error::from_raw_os_error(6)); + assert_eq!(into_neg_errno(os_err), -6); + } + } + + #[test] + pub fn test_isize() { + assert_match!(into_io_result(1234isize), Ok(1234)); + + let err = into_io_result(-4isize).unwrap_err(); + #[cfg(unix)] + assert_match!(err.raw_os_error(), Some(4)); + assert_match!(err.kind(), ErrorKind::Interrupted); + } + + #[test] + pub fn test_from_unit() { + let ok: io::Result<_> = Ok(()); + assert_eq!(into_neg_errno(ok), 0); + + let err: io::Result<()> = Err(io::ErrorKind::OutOfMemory.into()); + assert_eq!(into_neg_errno(err), -12); + + if cfg!(unix) { + let os_err: io::Result<()> = Err(io::Error::from_raw_os_error(2)); + assert_eq!(into_neg_errno(os_err), -2); + } + } +} diff --git a/rust/common/src/lib.rs b/rust/common/src/lib.rs new file mode 100644 index 0000000000..25216503aa --- /dev/null +++ b/rust/common/src/lib.rs @@ -0,0 +1,20 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +pub mod assertions; + +pub mod bitops; + +pub mod callbacks; +pub use callbacks::FnCall; + +pub mod errno; +pub use errno::Errno; + +pub mod opaque; +pub use opaque::{Opaque, Wrapper}; + +pub mod uninit; +pub use uninit::MaybeUninitField; + +pub mod zeroable; +pub use zeroable::Zeroable; diff --git a/rust/common/src/opaque.rs b/rust/common/src/opaque.rs new file mode 100644 index 0000000000..d25a5f3ae1 --- /dev/null +++ b/rust/common/src/opaque.rs @@ -0,0 +1,238 @@ +// SPDX-License-Identifier: MIT + +//! ## Opaque wrappers +//! +//! The cell types from the previous section are useful at the boundaries +//! of code that requires interior mutability. When writing glue code that +//! interacts directly with C structs, however, it is useful to operate +//! at a lower level. +//! +//! C functions often violate Rust's fundamental assumptions about memory +//! safety by modifying memory even if it is shared. Furthermore, C structs +//! often start their life uninitialized and may be populated lazily. +//! +//! For this reason, this module provides the [`Opaque`] type to opt out +//! of Rust's usual guarantees about the wrapped type. Access to the wrapped +//! value is always through raw pointers, obtained via methods like +//! [`as_mut_ptr()`](Opaque::as_mut_ptr) and [`as_ptr()`](Opaque::as_ptr). These +//! pointers can then be passed to C functions or dereferenced; both actions +//! require `unsafe` blocks, making it clear where safety guarantees must be +//! manually verified. For example +//! +//! ```ignore +//! unsafe { +//! let state = Opaque::::uninit(); +//! qemu_struct_init(state.as_mut_ptr()); +//! } +//! ``` +//! +//! [`Opaque`] will usually be wrapped one level further, so that +//! bridge methods can be added to the wrapper: +//! +//! ```ignore +//! pub struct MyStruct(Opaque); +//! +//! impl MyStruct { +//! fn new() -> Pin> { +//! let result = Box::pin(unsafe { Opaque::uninit() }); +//! unsafe { qemu_struct_init(result.as_mut_ptr()) }; +//! result +//! } +//! } +//! ``` +//! +//! This pattern of wrapping bindgen-generated types in [`Opaque`] provides +//! several advantages: +//! +//! * The choice of traits to be implemented is not limited by the +//! bindgen-generated code. For example, [`Drop`] can be added without +//! disabling [`Copy`] on the underlying bindgen type +//! +//! * [`Send`] and [`Sync`] implementations can be controlled by the wrapper +//! type rather than being automatically derived from the C struct's layout +//! +//! * Methods can be implemented in a separate crate from the bindgen-generated +//! bindings +//! +//! * [`Debug`](std::fmt::Debug) and [`Display`](std::fmt::Display) +//! implementations can be customized to be more readable than the raw C +//! struct representation +//! +//! The [`Opaque`] type does not include BQL validation; it is possible to +//! assert in the code that the right lock is taken, to use it together +//! with a custom lock guard type, or to let C code take the lock, as +//! appropriate. It is also possible to use it with non-thread-safe +//! types, since by default (unlike [`BqlCell`] and [`BqlRefCell`] +//! it is neither `Sync` nor `Send`. +//! +//! While [`Opaque`] is necessary for C interop, it should be used sparingly +//! and only at FFI boundaries. For QEMU-specific types that need interior +//! mutability, prefer [`BqlCell`] or [`BqlRefCell`]. +//! +//! [`BqlCell`]: ../../qemu_api/cell/struct.BqlCell.html +//! [`BqlRefCell`]: ../../qemu_api/cell/struct.BqlRefCell.html +use std::{cell::UnsafeCell, fmt, marker::PhantomPinned, mem::MaybeUninit, ptr::NonNull}; + +/// Stores an opaque value that is shared with C code. +/// +/// Often, C structs can changed when calling a C function even if they are +/// behind a shared Rust reference, or they can be initialized lazily and have +/// invalid bit patterns (e.g. `3` for a [`bool`]). This goes against Rust's +/// strict aliasing rules, which normally prevent mutation through shared +/// references. +/// +/// Wrapping the struct with `Opaque` ensures that the Rust compiler does not +/// assume the usual constraints that Rust structs require, and allows using +/// shared references on the Rust side. +/// +/// `Opaque` is `#[repr(transparent)]`, so that it matches the memory layout +/// of `T`. +#[repr(transparent)] +pub struct Opaque { + value: UnsafeCell>, + // PhantomPinned also allows multiple references to the `Opaque`, i.e. + // one `&mut Opaque` can coexist with a `&mut T` or any number of `&T`; + // see https://docs.rs/pinned-aliasable/latest/pinned_aliasable/. + _pin: PhantomPinned, +} + +impl Opaque { + /// Creates a new shared reference from a C pointer + /// + /// # Safety + /// + /// The pointer must be valid, though it need not point to a valid value. + pub unsafe fn from_raw<'a>(ptr: *mut T) -> &'a Self { + let ptr = NonNull::new(ptr).unwrap().cast::(); + // SAFETY: Self is a transparent wrapper over T + unsafe { ptr.as_ref() } + } + + /// Creates a new opaque object with uninitialized contents. + /// + /// # Safety + /// + /// Ultimately the pointer to the returned value will be dereferenced + /// in another `unsafe` block, for example when passing it to a C function, + /// but the functions containing the dereference are usually safe. The + /// value returned from `uninit()` must be initialized and pinned before + /// calling them. + pub const unsafe fn uninit() -> Self { + Self { + value: UnsafeCell::new(MaybeUninit::uninit()), + _pin: PhantomPinned, + } + } + + /// Creates a new opaque object with zeroed contents. + /// + /// # Safety + /// + /// Ultimately the pointer to the returned value will be dereferenced + /// in another `unsafe` block, for example when passing it to a C function, + /// but the functions containing the dereference are usually safe. The + /// value returned from `uninit()` must be pinned (and possibly initialized) + /// before calling them. + pub const unsafe fn zeroed() -> Self { + Self { + value: UnsafeCell::new(MaybeUninit::zeroed()), + _pin: PhantomPinned, + } + } + + /// Returns a raw mutable pointer to the opaque data. + pub const fn as_mut_ptr(&self) -> *mut T { + UnsafeCell::get(&self.value).cast() + } + + /// Returns a raw pointer to the opaque data. + pub const fn as_ptr(&self) -> *const T { + self.as_mut_ptr().cast_const() + } + + /// Returns a raw pointer to the opaque data that can be passed to a + /// C function as `void *`. + pub const fn as_void_ptr(&self) -> *mut std::ffi::c_void { + UnsafeCell::get(&self.value).cast() + } + + /// Converts a raw pointer to the wrapped type. + pub const fn raw_get(slot: *mut Self) -> *mut T { + // Compare with Linux's raw_get method, which goes through an UnsafeCell + // because it takes a *const Self instead. + slot.cast() + } +} + +impl fmt::Debug for Opaque { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + let mut name: String = "Opaque<".to_string(); + name += std::any::type_name::(); + name += ">"; + f.debug_tuple(&name).field(&self.as_ptr()).finish() + } +} + +impl Opaque { + /// Creates a new opaque object with default contents. + /// + /// # Safety + /// + /// Ultimately the pointer to the returned value will be dereferenced + /// in another `unsafe` block, for example when passing it to a C function, + /// but the functions containing the dereference are usually safe. The + /// value returned from `uninit()` must be pinned before calling them. + pub unsafe fn new() -> Self { + Self { + value: UnsafeCell::new(MaybeUninit::new(T::default())), + _pin: PhantomPinned, + } + } +} + +/// Annotates [`Self`] as a transparent wrapper for another type. +/// +/// Usually defined via the [`qemu_api_macros::Wrapper`] derive macro. +/// +/// # Examples +/// +/// ``` +/// # use std::mem::ManuallyDrop; +/// # use common::opaque::Wrapper; +/// #[repr(transparent)] +/// pub struct Example { +/// inner: ManuallyDrop, +/// } +/// +/// unsafe impl Wrapper for Example { +/// type Wrapped = String; +/// } +/// ``` +/// +/// # Safety +/// +/// `Self` must be a `#[repr(transparent)]` wrapper for the `Wrapped` type, +/// whether directly or indirectly. +/// +/// # Methods +/// +/// By convention, types that implement Wrapper also implement the following +/// methods: +/// +/// ```ignore +/// pub const unsafe fn from_raw<'a>(value: *mut Self::Wrapped) -> &'a Self; +/// pub const unsafe fn as_mut_ptr(&self) -> *mut Self::Wrapped; +/// pub const unsafe fn as_ptr(&self) -> *const Self::Wrapped; +/// pub const unsafe fn raw_get(slot: *mut Self) -> *const Self::Wrapped; +/// ``` +/// +/// They are not defined here to allow them to be `const`. +/// +/// [`qemu_api_macros::Wrapper`]: ../../qemu_api_macros/derive.Wrapper.html +pub unsafe trait Wrapper { + type Wrapped; +} + +unsafe impl Wrapper for Opaque { + type Wrapped = T; +} diff --git a/rust/common/src/uninit.rs b/rust/common/src/uninit.rs new file mode 100644 index 0000000000..e7f9fcd2e3 --- /dev/null +++ b/rust/common/src/uninit.rs @@ -0,0 +1,85 @@ +//! Access fields of a [`MaybeUninit`] + +use std::{ + mem::MaybeUninit, + ops::{Deref, DerefMut}, +}; + +pub struct MaybeUninitField<'a, T, U> { + parent: &'a mut MaybeUninit, + child: *mut U, +} + +impl<'a, T, U> MaybeUninitField<'a, T, U> { + #[doc(hidden)] + pub const fn new(parent: &'a mut MaybeUninit, child: *mut U) -> Self { + MaybeUninitField { parent, child } + } + + /// Return a constant pointer to the containing object of the field. + /// + /// Because the `MaybeUninitField` remembers the containing object, + /// it is possible to use it in foreign APIs that initialize the + /// child. + pub const fn parent(f: &Self) -> *const T { + f.parent.as_ptr() + } + + /// Return a mutable pointer to the containing object. + /// + /// Because the `MaybeUninitField` remembers the containing object, + /// it is possible to use it in foreign APIs that initialize the + /// child. + pub const fn parent_mut(f: &mut Self) -> *mut T { + f.parent.as_mut_ptr() + } +} + +impl<'a, T, U> Deref for MaybeUninitField<'a, T, U> { + type Target = MaybeUninit; + + fn deref(&self) -> &MaybeUninit { + // SAFETY: self.child was obtained by dereferencing a valid mutable + // reference; the content of the memory may be invalid or uninitialized + // but MaybeUninit<_> makes no assumption on it + unsafe { &*(self.child.cast()) } + } +} + +impl<'a, T, U> DerefMut for MaybeUninitField<'a, T, U> { + fn deref_mut(&mut self) -> &mut MaybeUninit { + // SAFETY: self.child was obtained by dereferencing a valid mutable + // reference; the content of the memory may be invalid or uninitialized + // but MaybeUninit<_> makes no assumption on it + unsafe { &mut *(self.child.cast()) } + } +} + +/// ``` +/// #[derive(Debug)] +/// struct S { +/// x: u32, +/// y: u32, +/// } +/// +/// # use std::mem::MaybeUninit; +/// # use common::{assert_match, uninit_field_mut}; +/// +/// let mut s: MaybeUninit = MaybeUninit::zeroed(); +/// uninit_field_mut!(s, x).write(5); +/// let s = unsafe { s.assume_init() }; +/// assert_match!(s, S { x: 5, y: 0 }); +/// ``` +#[macro_export] +macro_rules! uninit_field_mut { + ($container:expr, $($field:tt)+) => {{ + let container__: &mut ::std::mem::MaybeUninit<_> = &mut $container; + let container_ptr__ = container__.as_mut_ptr(); + + // SAFETY: the container is not used directly, only through a MaybeUninit<>, + // so the safety is delegated to the caller and to final invocation of + // assume_init() + let target__ = unsafe { std::ptr::addr_of_mut!((*container_ptr__).$($field)+) }; + $crate::uninit::MaybeUninitField::new(container__, target__) + }}; +} diff --git a/rust/common/src/zeroable.rs b/rust/common/src/zeroable.rs new file mode 100644 index 0000000000..fd056deb1f --- /dev/null +++ b/rust/common/src/zeroable.rs @@ -0,0 +1,18 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +//! Defines a trait for structs that can be safely initialized with zero bytes. + +/// Encapsulates the requirement that +/// `MaybeUninit::::zeroed().assume_init()` does not cause undefined +/// behavior. +/// +/// # Safety +/// +/// Do not add this trait to a type unless all-zeroes is a valid value for the +/// type. In particular, raw pointers can be zero, but references and +/// `NonNull` cannot. +pub unsafe trait Zeroable: Default { + /// Return a value of Self whose memory representation consists of all + /// zeroes, with the possible exclusion of padding bytes. + const ZERO: Self = unsafe { ::core::mem::MaybeUninit::::zeroed().assume_init() }; +} diff --git a/rust/hw/char/pl011/Cargo.toml b/rust/hw/char/pl011/Cargo.toml index 88ef110507..6d15f107df 100644 --- a/rust/hw/char/pl011/Cargo.toml +++ b/rust/hw/char/pl011/Cargo.toml @@ -16,6 +16,7 @@ rust-version.workspace = true bilge = { version = "0.2.0" } bilge-impl = { version = "0.2.0" } bits = { path = "../../../bits" } +common = { path = "../../../common" } qemu_api = { path = "../../../qemu-api" } qemu_api_macros = { path = "../../../qemu-api-macros" } diff --git a/rust/hw/char/pl011/meson.build b/rust/hw/char/pl011/meson.build index 2a1be329ab..c4a9f531f7 100644 --- a/rust/hw/char/pl011/meson.build +++ b/rust/hw/char/pl011/meson.build @@ -7,7 +7,8 @@ _libpl011_rs = static_library( bilge_rs, bilge_impl_rs, bits_rs, - qemu_api, + common_rs, + qemu_api_rs, qemu_api_macros, ], ) diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs index 8411db8d00..b4aa6c45f8 100644 --- a/rust/hw/char/pl011/src/device.rs +++ b/rust/hw/char/pl011/src/device.rs @@ -4,6 +4,7 @@ use std::{ffi::CStr, mem::size_of}; +use common::{static_assert, uninit_field_mut}; use qemu_api::{ chardev::{CharBackend, Chardev, Event}, impl_vmstate_forward, impl_vmstate_struct, @@ -14,9 +15,7 @@ use qemu_api::{ prelude::*, qdev::{Clock, ClockEvent, DeviceImpl, DeviceState, ResetType, ResettablePhasesImpl}, qom::{ObjectImpl, Owned, ParentField, ParentInit}, - static_assert, sysbus::{SysBusDevice, SysBusDeviceImpl}, - uninit_field_mut, vmstate::{self, VMStateDescription, VMStateDescriptionBuilder}, vmstate_fields, vmstate_of, vmstate_subsections, vmstate_unused, }; diff --git a/rust/hw/timer/hpet/Cargo.toml b/rust/hw/timer/hpet/Cargo.toml index ac5df23c1d..ba7354f07e 100644 --- a/rust/hw/timer/hpet/Cargo.toml +++ b/rust/hw/timer/hpet/Cargo.toml @@ -11,6 +11,7 @@ repository.workspace = true rust-version.workspace = true [dependencies] +common = { path = "../../../common" } qemu_api = { path = "../../../qemu-api" } qemu_api_macros = { path = "../../../qemu-api-macros" } diff --git a/rust/hw/timer/hpet/meson.build b/rust/hw/timer/hpet/meson.build index c2d7c0532c..c91d330439 100644 --- a/rust/hw/timer/hpet/meson.build +++ b/rust/hw/timer/hpet/meson.build @@ -4,7 +4,8 @@ _libhpet_rs = static_library( override_options: ['rust_std=2021', 'build.rust_std=2021'], rust_abi: 'rust', dependencies: [ - qemu_api, + common_rs, + qemu_api_rs, qemu_api_macros, ], ) diff --git a/rust/hw/timer/hpet/src/device.rs b/rust/hw/timer/hpet/src/device.rs index dd5326a40d..72375d3155 100644 --- a/rust/hw/timer/hpet/src/device.rs +++ b/rust/hw/timer/hpet/src/device.rs @@ -10,6 +10,7 @@ use std::{ slice::from_ref, }; +use common::{bitops::IntegerExt, uninit_field_mut}; use qemu_api::{ bindings::{ address_space_memory, address_space_stl_le, qdev_prop_bit, qdev_prop_bool, @@ -27,7 +28,6 @@ use qemu_api::{ qom_isa, sysbus::{SysBusDevice, SysBusDeviceImpl}, timer::{Timer, CLOCK_VIRTUAL, NANOSECONDS_PER_SECOND}, - uninit_field_mut, vmstate::{self, VMStateDescription, VMStateDescriptionBuilder}, vmstate_fields, vmstate_of, vmstate_subsections, vmstate_validate, }; diff --git a/rust/hw/timer/hpet/src/fw_cfg.rs b/rust/hw/timer/hpet/src/fw_cfg.rs index 619d662ee1..0605225fbb 100644 --- a/rust/hw/timer/hpet/src/fw_cfg.rs +++ b/rust/hw/timer/hpet/src/fw_cfg.rs @@ -4,7 +4,8 @@ use std::ptr::addr_of_mut; -use qemu_api::{cell::bql_locked, zeroable::Zeroable}; +use common::Zeroable; +use qemu_api::cell::bql_locked; /// Each `HPETState` represents a Event Timer Block. The v1 spec supports /// up to 8 blocks. QEMU only uses 1 block (in PC machine). diff --git a/rust/meson.build b/rust/meson.build index 331f11b7e7..402f8d6600 100644 --- a/rust/meson.build +++ b/rust/meson.build @@ -22,6 +22,7 @@ qemuutil_rs = qemuutil.partial_dependency(link_args: true, links: true) genrs = [] +subdir('common') subdir('qemu-api-macros') subdir('bits') subdir('qemu-api') diff --git a/rust/qemu-api-macros/src/lib.rs b/rust/qemu-api-macros/src/lib.rs index a65a7ce2fe..49003a4780 100644 --- a/rust/qemu-api-macros/src/lib.rs +++ b/rust/qemu-api-macros/src/lib.rs @@ -97,7 +97,7 @@ fn derive_object_or_error(input: DeriveInput) -> Result::ParentType>); ::qemu_api::module_init! { @@ -125,20 +125,20 @@ fn derive_opaque_or_error(input: DeriveInput) -> Result::Wrapped; + unsafe impl ::common::opaque::Wrapper for #name { + type Wrapped = <#typ as ::common::opaque::Wrapper>::Wrapped; } impl #name { - pub unsafe fn from_raw<'a>(ptr: *mut ::Wrapped) -> &'a Self { + pub unsafe fn from_raw<'a>(ptr: *mut ::Wrapped) -> &'a Self { let ptr = ::std::ptr::NonNull::new(ptr).unwrap().cast::(); unsafe { ptr.as_ref() } } - pub const fn as_mut_ptr(&self) -> *mut ::Wrapped { + pub const fn as_mut_ptr(&self) -> *mut ::Wrapped { self.0.as_mut_ptr() } - pub const fn as_ptr(&self) -> *const ::Wrapped { + pub const fn as_ptr(&self) -> *const ::Wrapped { self.0.as_ptr() } @@ -146,7 +146,7 @@ fn derive_opaque_or_error(input: DeriveInput) -> Result *mut ::Wrapped { + pub const fn raw_get(slot: *mut Self) -> *mut ::Wrapped { slot.cast() } } @@ -282,7 +282,7 @@ fn derive_device_or_error(input: DeriveInput) -> Result::ParentType> diff --git a/rust/qemu-api/Cargo.toml b/rust/qemu-api/Cargo.toml index c5ed78035b..2e0e204491 100644 --- a/rust/qemu-api/Cargo.toml +++ b/rust/qemu-api/Cargo.toml @@ -14,6 +14,7 @@ repository.workspace = true rust-version.workspace = true [dependencies] +common = { path = "../common" } qemu_api_macros = { path = "../qemu-api-macros" } anyhow = { workspace = true } foreign = { workspace = true } diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index 062009f161..64af3caef5 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -52,13 +52,9 @@ _qemu_api_rs = static_library( structured_sources( [ 'src/lib.rs', - 'src/assertions.rs', 'src/bindings.rs', - 'src/bitops.rs', - 'src/callbacks.rs', 'src/cell.rs', 'src/chardev.rs', - 'src/errno.rs', 'src/error.rs', 'src/irq.rs', 'src/log.rs', @@ -69,23 +65,21 @@ _qemu_api_rs = static_library( 'src/qom.rs', 'src/sysbus.rs', 'src/timer.rs', - 'src/uninit.rs', 'src/vmstate.rs', - 'src/zeroable.rs', ], {'.' : _qemu_api_bindings_inc_rs}, ), override_options: ['rust_std=2021', 'build.rust_std=2021'], rust_abi: 'rust', rust_args: _qemu_api_cfg, - dependencies: [anyhow_rs, foreign_rs, libc_rs, qemu_api_macros, qemuutil_rs, + dependencies: [anyhow_rs, common_rs, foreign_rs, libc_rs, qemu_api_macros, qemuutil_rs, qom, hwcore, chardev, migration], ) rust.test('rust-qemu-api-tests', _qemu_api_rs, suite: ['unit', 'rust']) -qemu_api = declare_dependency(link_with: [_qemu_api_rs], +qemu_api_rs = declare_dependency(link_with: [_qemu_api_rs], dependencies: [qemu_api_macros, qom, hwcore, chardev, migration]) # Doctests are essentially integration tests, so they need the same dependencies. @@ -94,7 +88,7 @@ qemu_api = declare_dependency(link_with: [_qemu_api_rs], rust.doctest('rust-qemu-api-doctests', _qemu_api_rs, protocol: 'rust', - dependencies: qemu_api, + dependencies: [qemu_api_rs], suite: ['doc', 'rust']) test('rust-qemu-api-integration', @@ -104,7 +98,7 @@ test('rust-qemu-api-integration', override_options: ['rust_std=2021', 'build.rust_std=2021'], rust_args: ['--test'], install: false, - dependencies: [qemu_api]), + dependencies: [common_rs, qemu_api_rs]), args: [ '--test', '--test-threads', '1', '--format', 'pretty', diff --git a/rust/qemu-api/src/assertions.rs b/rust/qemu-api/src/assertions.rs deleted file mode 100644 index e4fe23b674..0000000000 --- a/rust/qemu-api/src/assertions.rs +++ /dev/null @@ -1,148 +0,0 @@ -// Copyright 2024, Red Hat Inc. -// Author(s): Paolo Bonzini -// SPDX-License-Identifier: GPL-2.0-or-later - -#![doc(hidden)] -//! This module provides macros to check the equality of types and -//! the type of `struct` fields. This can be useful to ensure that -//! types match the expectations of C code. -//! -//! Documentation is hidden because it only exposes macros, which -//! are exported directly from `qemu_api`. - -// Based on https://stackoverflow.com/questions/64251852/x/70978292#70978292 -// (stackoverflow answers are released under MIT license). - -#[doc(hidden)] -pub trait EqType { - type Itself; -} - -impl EqType for T { - type Itself = T; -} - -/// Assert that two types are the same. -/// -/// # Examples -/// -/// ``` -/// # use qemu_api::assert_same_type; -/// # use std::ops::Deref; -/// assert_same_type!(u32, u32); -/// assert_same_type!( as Deref>::Target, u32); -/// ``` -/// -/// Different types will cause a compile failure -/// -/// ```compile_fail -/// # use qemu_api::assert_same_type; -/// assert_same_type!(&Box, &u32); -/// ``` -#[macro_export] -macro_rules! assert_same_type { - ($t1:ty, $t2:ty) => { - const _: () = { - #[allow(unused)] - fn assert_same_type(v: $t1) { - fn types_must_be_equal(_: T) - where - T: $crate::assertions::EqType, - { - } - types_must_be_equal::<_, $t2>(v); - } - }; - }; -} - -/// Assert that a field of a struct has the given type. -/// -/// # Examples -/// -/// ``` -/// # use qemu_api::assert_field_type; -/// pub struct A { -/// field1: u32, -/// } -/// -/// assert_field_type!(A, field1, u32); -/// ``` -/// -/// Different types will cause a compile failure -/// -/// ```compile_fail -/// # use qemu_api::assert_field_type; -/// # pub struct A { field1: u32 } -/// assert_field_type!(A, field1, i32); -/// ``` -#[macro_export] -macro_rules! assert_field_type { - (@internal $param_name:ident, $ti:ty, $t:ty, $($field:tt)*) => { - const _: () = { - #[allow(unused)] - const fn assert_field_type($param_name: &$t) { - const fn types_must_be_equal(_: &T) - where - T: $crate::assertions::EqType, - { - } - types_must_be_equal::<_, $ti>(&$($field)*); - } - }; - }; - - ($t:ty, $i:tt, $ti:ty) => { - $crate::assert_field_type!(@internal v, $ti, $t, v.$i); - }; -} - -/// Assert that an expression matches a pattern. This can also be -/// useful to compare enums that do not implement `Eq`. -/// -/// # Examples -/// -/// ``` -/// # use qemu_api::assert_match; -/// // JoinHandle does not implement `Eq`, therefore the result -/// // does not either. -/// let result: Result, u32> = Err(42); -/// assert_match!(result, Err(42)); -/// ``` -#[macro_export] -macro_rules! assert_match { - ($a:expr, $b:pat) => { - assert!( - match $a { - $b => true, - _ => false, - }, - "{} = {:?} does not match {}", - stringify!($a), - $a, - stringify!($b) - ); - }; -} - -/// Assert at compile time that an expression is true. This is similar -/// to `const { assert!(...); }` but it works outside functions, as well as -/// on versions of Rust before 1.79. -/// -/// # Examples -/// -/// ``` -/// # use qemu_api::static_assert; -/// static_assert!("abc".len() == 3); -/// ``` -/// -/// ```compile_fail -/// # use qemu_api::static_assert; -/// static_assert!("abc".len() == 2); // does not compile -/// ``` -#[macro_export] -macro_rules! static_assert { - ($x:expr) => { - const _: () = assert!($x); - }; -} diff --git a/rust/qemu-api/src/bindings.rs b/rust/qemu-api/src/bindings.rs index b8104dea8b..3acdd903b5 100644 --- a/rust/qemu-api/src/bindings.rs +++ b/rust/qemu-api/src/bindings.rs @@ -20,6 +20,8 @@ //! `bindgen`-generated declarations. +use common::Zeroable; + #[cfg(MESON)] include!("bindings.inc.rs"); @@ -56,3 +58,22 @@ unsafe impl Sync for VMStateField {} unsafe impl Send for VMStateInfo {} unsafe impl Sync for VMStateInfo {} + +// bindgen does not derive Default here +#[allow(clippy::derivable_impls)] +impl Default for crate::bindings::VMStateFlags { + fn default() -> Self { + Self(0) + } +} + +unsafe impl Zeroable for crate::bindings::Property__bindgen_ty_1 {} +unsafe impl Zeroable for crate::bindings::Property {} +unsafe impl Zeroable for crate::bindings::VMStateFlags {} +unsafe impl Zeroable for crate::bindings::VMStateField {} +unsafe impl Zeroable for crate::bindings::VMStateDescription {} +unsafe impl Zeroable for crate::bindings::MemoryRegionOps__bindgen_ty_1 {} +unsafe impl Zeroable for crate::bindings::MemoryRegionOps__bindgen_ty_2 {} +unsafe impl Zeroable for crate::bindings::MemoryRegionOps {} +unsafe impl Zeroable for crate::bindings::MemTxAttrs {} +unsafe impl Zeroable for crate::bindings::CharBackend {} diff --git a/rust/qemu-api/src/bitops.rs b/rust/qemu-api/src/bitops.rs deleted file mode 100644 index b1e3a530ab..0000000000 --- a/rust/qemu-api/src/bitops.rs +++ /dev/null @@ -1,119 +0,0 @@ -// Copyright (C) 2024 Intel Corporation. -// Author(s): Zhao Liu -// SPDX-License-Identifier: GPL-2.0-or-later - -//! This module provides bit operation extensions to integer types. -//! It is usually included via the `qemu_api` prelude. - -use std::ops::{ - Add, AddAssign, BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Div, DivAssign, - Mul, MulAssign, Not, Rem, RemAssign, Shl, ShlAssign, Shr, ShrAssign, -}; - -/// Trait for extensions to integer types -pub trait IntegerExt: - Add + AddAssign + - BitAnd + BitAndAssign + - BitOr + BitOrAssign + - BitXor + BitXorAssign + - Copy + - Div + DivAssign + - Eq + - Mul + MulAssign + - Not + Ord + PartialOrd + - Rem + RemAssign + - Shl + ShlAssign + - Shl + ShlAssign + // add more as needed - Shr + ShrAssign + - Shr + ShrAssign // add more as needed -{ - const BITS: u32; - const MAX: Self; - const MIN: Self; - const ONE: Self; - const ZERO: Self; - - #[inline] - #[must_use] - fn bit(start: u32) -> Self - { - debug_assert!(start < Self::BITS); - - Self::ONE << start - } - - #[inline] - #[must_use] - fn mask(start: u32, length: u32) -> Self - { - /* FIXME: Implement a more elegant check with error handling support? */ - debug_assert!(start < Self::BITS && length > 0 && length <= Self::BITS - start); - - (Self::MAX >> (Self::BITS - length)) << start - } - - #[inline] - #[must_use] - fn deposit(self, start: u32, length: u32, - fieldval: U) -> Self - where Self: From - { - debug_assert!(length <= U::BITS); - - let mask = Self::mask(start, length); - (self & !mask) | ((Self::from(fieldval) << start) & mask) - } - - #[inline] - #[must_use] - fn extract(self, start: u32, length: u32) -> Self - { - let mask = Self::mask(start, length); - (self & mask) >> start - } -} - -macro_rules! impl_num_ext { - ($type:ty) => { - impl IntegerExt for $type { - const BITS: u32 = <$type>::BITS; - const MAX: Self = <$type>::MAX; - const MIN: Self = <$type>::MIN; - const ONE: Self = 1; - const ZERO: Self = 0; - } - }; -} - -impl_num_ext!(u8); -impl_num_ext!(u16); -impl_num_ext!(u32); -impl_num_ext!(u64); - -#[cfg(test)] -mod tests { - use super::*; - - #[test] - fn test_deposit() { - assert_eq!(15u32.deposit(8, 8, 1u32), 256 + 15); - assert_eq!(15u32.deposit(8, 1, 255u8), 256 + 15); - } - - #[test] - fn test_extract() { - assert_eq!(15u32.extract(2, 4), 3); - } - - #[test] - fn test_bit() { - assert_eq!(u8::bit(7), 128); - assert_eq!(u32::bit(16), 0x10000); - } - - #[test] - fn test_mask() { - assert_eq!(u8::mask(7, 1), 128); - assert_eq!(u32::mask(8, 8), 0xff00); - } -} diff --git a/rust/qemu-api/src/callbacks.rs b/rust/qemu-api/src/callbacks.rs deleted file mode 100644 index dbe2305f50..0000000000 --- a/rust/qemu-api/src/callbacks.rs +++ /dev/null @@ -1,216 +0,0 @@ -// SPDX-License-Identifier: MIT - -//! Utility functions to deal with callbacks from C to Rust. - -use std::{mem, ptr::NonNull}; - -/// Trait for functions (types implementing [`Fn`]) that can be used as -/// callbacks. These include both zero-capture closures and function pointers. -/// -/// In Rust, calling a function through the `Fn` trait normally requires a -/// `self` parameter, even though for zero-sized functions (including function -/// pointers) the type itself contains all necessary information to call the -/// function. This trait provides a `call` function that doesn't require `self`, -/// allowing zero-sized functions to be called using only their type. -/// -/// This enables zero-sized functions to be passed entirely through generic -/// parameters and resolved at compile-time. A typical use is a function -/// receiving an unused parameter of generic type `F` and calling it via -/// `F::call` or passing it to another function via `func::`. -/// -/// QEMU uses this trick to create wrappers to C callbacks. The wrappers -/// are needed to convert an opaque `*mut c_void` into a Rust reference, -/// but they only have a single opaque that they can use. The `FnCall` -/// trait makes it possible to use that opaque for `self` or any other -/// reference: -/// -/// ```ignore -/// // The compiler creates a new `rust_bh_cb` wrapper for each function -/// // passed to `qemu_bh_schedule_oneshot` below. -/// unsafe extern "C" fn rust_bh_cb FnCall<(&'a T,)>>( -/// opaque: *mut c_void, -/// ) { -/// // SAFETY: the opaque was passed as a reference to `T`. -/// F::call((unsafe { &*(opaque.cast::()) }, )) -/// } -/// -/// // The `_f` parameter is unused but it helps the compiler build the appropriate `F`. -/// // Using a reference allows usage in const context. -/// fn qemu_bh_schedule_oneshot FnCall<(&'a T,)>>(_f: &F, opaque: &T) { -/// let cb: unsafe extern "C" fn(*mut c_void) = rust_bh_cb::; -/// unsafe { -/// bindings::qemu_bh_schedule_oneshot(cb, opaque as *const T as *const c_void as *mut c_void) -/// } -/// } -/// ``` -/// -/// Each wrapper is a separate instance of `rust_bh_cb` and is therefore -/// compiled to a separate function ("monomorphization"). If you wanted -/// to pass `self` as the opaque value, the generic parameters would be -/// `rust_bh_cb::`. -/// -/// `Args` is a tuple type whose types are the arguments of the function, -/// while `R` is the returned type. -/// -/// # Examples -/// -/// ``` -/// # use qemu_api::callbacks::FnCall; -/// fn call_it FnCall<(&'a str,), String>>(_f: &F, s: &str) -> String { -/// F::call((s,)) -/// } -/// -/// let s: String = call_it(&str::to_owned, "hello world"); -/// assert_eq!(s, "hello world"); -/// ``` -/// -/// Note that the compiler will produce a different version of `call_it` for -/// each function that is passed to it. Therefore the argument is not really -/// used, except to decide what is `F` and what `F::call` does. -/// -/// Attempting to pass a non-zero-sized closure causes a compile-time failure: -/// -/// ```compile_fail -/// # use qemu_api::callbacks::FnCall; -/// # fn call_it<'a, F: FnCall<(&'a str,), String>>(_f: &F, s: &'a str) -> String { -/// # F::call((s,)) -/// # } -/// let x: &'static str = "goodbye world"; -/// call_it(&move |_| String::from(x), "hello workd"); -/// ``` -/// -/// `()` can be used to indicate "no function": -/// -/// ``` -/// # use qemu_api::callbacks::FnCall; -/// fn optional FnCall<(&'a str,), String>>(_f: &F, s: &str) -> Option { -/// if F::IS_SOME { -/// Some(F::call((s,))) -/// } else { -/// None -/// } -/// } -/// -/// assert!(optional(&(), "hello world").is_none()); -/// ``` -/// -/// Invoking `F::call` will then be a run-time error. -/// -/// ```should_panic -/// # use qemu_api::callbacks::FnCall; -/// # fn call_it FnCall<(&'a str,), String>>(_f: &F, s: &str) -> String { -/// # F::call((s,)) -/// # } -/// let s: String = call_it(&(), "hello world"); // panics -/// ``` -/// -/// # Safety -/// -/// Because `Self` is a zero-sized type, all instances of the type are -/// equivalent. However, in addition to this, `Self` must have no invariants -/// that could be violated by creating a reference to it. -/// -/// This is always true for zero-capture closures and function pointers, as long -/// as the code is able to name the function in the first place. -pub unsafe trait FnCall: 'static + Sync + Sized { - /// `true` if `Self` is an actual function type and not `()`. - /// - /// # Examples - /// - /// You can use `IS_SOME` to catch this at compile time: - /// - /// ```compile_fail - /// # use qemu_api::callbacks::FnCall; - /// fn call_it FnCall<(&'a str,), String>>(_f: &F, s: &str) -> String { - /// const { assert!(F::IS_SOME) } - /// F::call((s,)) - /// } - /// - /// let s: String = call_it((), "hello world"); // does not compile - /// ``` - const IS_SOME: bool; - - /// `false` if `Self` is an actual function type, `true` if it is `()`. - fn is_none() -> bool { - !Self::IS_SOME - } - - /// `true` if `Self` is an actual function type, `false` if it is `()`. - fn is_some() -> bool { - Self::IS_SOME - } - - /// Call the function with the arguments in args. - fn call(a: Args) -> R; -} - -/// `()` acts as a "null" callback. Using `()` and `function` is nicer -/// than `None` and `Some(function)`, because the compiler is unable to -/// infer the type of just `None`. Therefore, the trait itself acts as the -/// option type, with functions [`FnCall::is_some`] and [`FnCall::is_none`]. -unsafe impl FnCall for () { - const IS_SOME: bool = false; - - /// Call the function with the arguments in args. - fn call(_a: Args) -> R { - panic!("callback not specified") - } -} - -macro_rules! impl_call { - ($($args:ident,)* ) => ( - // SAFETY: because each function is treated as a separate type, - // accessing `FnCall` is only possible in code that would be - // allowed to call the function. - unsafe impl FnCall<($($args,)*), R> for F - where - F: 'static + Sync + Sized + Fn($($args, )*) -> R, - { - const IS_SOME: bool = true; - - #[inline(always)] - fn call(a: ($($args,)*)) -> R { - const { assert!(mem::size_of::() == 0) }; - - // SAFETY: the safety of this method is the condition for implementing - // `FnCall`. As to the `NonNull` idiom to create a zero-sized type, - // see https://github.com/rust-lang/libs-team/issues/292. - let f: &'static F = unsafe { &*NonNull::::dangling().as_ptr() }; - let ($($args,)*) = a; - f($($args,)*) - } - } - ) -} - -impl_call!(_1, _2, _3, _4, _5,); -impl_call!(_1, _2, _3, _4,); -impl_call!(_1, _2, _3,); -impl_call!(_1, _2,); -impl_call!(_1,); -impl_call!(); - -#[cfg(test)] -mod tests { - use super::*; - - // The `_f` parameter is unused but it helps the compiler infer `F`. - fn do_test_call<'a, F: FnCall<(&'a str,), String>>(_f: &F) -> String { - F::call(("hello world",)) - } - - #[test] - fn test_call() { - assert_eq!(do_test_call(&str::to_owned), "hello world") - } - - // The `_f` parameter is unused but it helps the compiler infer `F`. - fn do_test_is_some<'a, F: FnCall<(&'a str,), String>>(_f: &F) { - assert!(F::is_some()); - } - - #[test] - fn test_is_some() { - do_test_is_some(&str::to_owned); - } -} diff --git a/rust/qemu-api/src/cell.rs b/rust/qemu-api/src/cell.rs index 9943d7286b..d13848df20 100644 --- a/rust/qemu-api/src/cell.rs +++ b/rust/qemu-api/src/cell.rs @@ -141,82 +141,13 @@ //! Multiple immutable borrows are allowed via [`borrow`](BqlRefCell::borrow), //! or a single mutable borrow via [`borrow_mut`](BqlRefCell::borrow_mut). The //! thread will panic if these rules are violated or if the BQL is not held. -//! -//! ## Opaque wrappers -//! -//! The cell types from the previous section are useful at the boundaries -//! of code that requires interior mutability. When writing glue code that -//! interacts directly with C structs, however, it is useful to operate -//! at a lower level. -//! -//! C functions often violate Rust's fundamental assumptions about memory -//! safety by modifying memory even if it is shared. Furthermore, C structs -//! often start their life uninitialized and may be populated lazily. -//! -//! For this reason, this module provides the [`Opaque`] type to opt out -//! of Rust's usual guarantees about the wrapped type. Access to the wrapped -//! value is always through raw pointers, obtained via methods like -//! [`as_mut_ptr()`](Opaque::as_mut_ptr) and [`as_ptr()`](Opaque::as_ptr). These -//! pointers can then be passed to C functions or dereferenced; both actions -//! require `unsafe` blocks, making it clear where safety guarantees must be -//! manually verified. For example -//! -//! ```ignore -//! unsafe { -//! let state = Opaque::::uninit(); -//! qemu_struct_init(state.as_mut_ptr()); -//! } -//! ``` -//! -//! [`Opaque`] will usually be wrapped one level further, so that -//! bridge methods can be added to the wrapper: -//! -//! ```ignore -//! pub struct MyStruct(Opaque); -//! -//! impl MyStruct { -//! fn new() -> Pin> { -//! let result = Box::pin(unsafe { Opaque::uninit() }); -//! unsafe { qemu_struct_init(result.as_mut_ptr()) }; -//! result -//! } -//! } -//! ``` -//! -//! This pattern of wrapping bindgen-generated types in [`Opaque`] provides -//! several advantages: -//! -//! * The choice of traits to be implemented is not limited by the -//! bindgen-generated code. For example, [`Drop`] can be added without -//! disabling [`Copy`] on the underlying bindgen type -//! -//! * [`Send`] and [`Sync`] implementations can be controlled by the wrapper -//! type rather than being automatically derived from the C struct's layout -//! -//! * Methods can be implemented in a separate crate from the bindgen-generated -//! bindings -//! -//! * [`Debug`](std::fmt::Debug) and [`Display`](std::fmt::Display) -//! implementations can be customized to be more readable than the raw C -//! struct representation -//! -//! The [`Opaque`] type does not include BQL validation; it is possible to -//! assert in the code that the right lock is taken, to use it together -//! with a custom lock guard type, or to let C code take the lock, as -//! appropriate. It is also possible to use it with non-thread-safe -//! types, since by default (unlike [`BqlCell`] and [`BqlRefCell`] -//! it is neither `Sync` nor `Send`. -//! -//! While [`Opaque`] is necessary for C interop, it should be used sparingly -//! and only at FFI boundaries. For QEMU-specific types that need interior -//! mutability, prefer [`BqlCell`] or [`BqlRefCell`]. use std::{ cell::{Cell, UnsafeCell}, cmp::Ordering, fmt, - marker::{PhantomData, PhantomPinned}, - mem::{self, MaybeUninit}, + marker::PhantomData, + mem, ops::{Deref, DerefMut}, ptr::NonNull, }; @@ -939,165 +870,3 @@ impl fmt::Display for BqlRefMut<'_, T> { (**self).fmt(f) } } - -/// Stores an opaque value that is shared with C code. -/// -/// Often, C structs can changed when calling a C function even if they are -/// behind a shared Rust reference, or they can be initialized lazily and have -/// invalid bit patterns (e.g. `3` for a [`bool`]). This goes against Rust's -/// strict aliasing rules, which normally prevent mutation through shared -/// references. -/// -/// Wrapping the struct with `Opaque` ensures that the Rust compiler does not -/// assume the usual constraints that Rust structs require, and allows using -/// shared references on the Rust side. -/// -/// `Opaque` is `#[repr(transparent)]`, so that it matches the memory layout -/// of `T`. -#[repr(transparent)] -pub struct Opaque { - value: UnsafeCell>, - // PhantomPinned also allows multiple references to the `Opaque`, i.e. - // one `&mut Opaque` can coexist with a `&mut T` or any number of `&T`; - // see https://docs.rs/pinned-aliasable/latest/pinned_aliasable/. - _pin: PhantomPinned, -} - -impl Opaque { - /// Creates a new shared reference from a C pointer - /// - /// # Safety - /// - /// The pointer must be valid, though it need not point to a valid value. - pub unsafe fn from_raw<'a>(ptr: *mut T) -> &'a Self { - let ptr = NonNull::new(ptr).unwrap().cast::(); - // SAFETY: Self is a transparent wrapper over T - unsafe { ptr.as_ref() } - } - - /// Creates a new opaque object with uninitialized contents. - /// - /// # Safety - /// - /// Ultimately the pointer to the returned value will be dereferenced - /// in another `unsafe` block, for example when passing it to a C function, - /// but the functions containing the dereference are usually safe. The - /// value returned from `uninit()` must be initialized and pinned before - /// calling them. - pub const unsafe fn uninit() -> Self { - Self { - value: UnsafeCell::new(MaybeUninit::uninit()), - _pin: PhantomPinned, - } - } - - /// Creates a new opaque object with zeroed contents. - /// - /// # Safety - /// - /// Ultimately the pointer to the returned value will be dereferenced - /// in another `unsafe` block, for example when passing it to a C function, - /// but the functions containing the dereference are usually safe. The - /// value returned from `uninit()` must be pinned (and possibly initialized) - /// before calling them. - pub const unsafe fn zeroed() -> Self { - Self { - value: UnsafeCell::new(MaybeUninit::zeroed()), - _pin: PhantomPinned, - } - } - - /// Returns a raw mutable pointer to the opaque data. - pub const fn as_mut_ptr(&self) -> *mut T { - UnsafeCell::get(&self.value).cast() - } - - /// Returns a raw pointer to the opaque data. - pub const fn as_ptr(&self) -> *const T { - self.as_mut_ptr().cast_const() - } - - /// Returns a raw pointer to the opaque data that can be passed to a - /// C function as `void *`. - pub const fn as_void_ptr(&self) -> *mut std::ffi::c_void { - UnsafeCell::get(&self.value).cast() - } - - /// Converts a raw pointer to the wrapped type. - pub const fn raw_get(slot: *mut Self) -> *mut T { - // Compare with Linux's raw_get method, which goes through an UnsafeCell - // because it takes a *const Self instead. - slot.cast() - } -} - -impl fmt::Debug for Opaque { - fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { - let mut name: String = "Opaque<".to_string(); - name += std::any::type_name::(); - name += ">"; - f.debug_tuple(&name).field(&self.as_ptr()).finish() - } -} - -impl Opaque { - /// Creates a new opaque object with default contents. - /// - /// # Safety - /// - /// Ultimately the pointer to the returned value will be dereferenced - /// in another `unsafe` block, for example when passing it to a C function, - /// but the functions containing the dereference are usually safe. The - /// value returned from `uninit()` must be pinned before calling them. - pub unsafe fn new() -> Self { - Self { - value: UnsafeCell::new(MaybeUninit::new(T::default())), - _pin: PhantomPinned, - } - } -} - -/// Annotates [`Self`] as a transparent wrapper for another type. -/// -/// Usually defined via the [`qemu_api_macros::Wrapper`] derive macro. -/// -/// # Examples -/// -/// ``` -/// # use std::mem::ManuallyDrop; -/// # use qemu_api::cell::Wrapper; -/// #[repr(transparent)] -/// pub struct Example { -/// inner: ManuallyDrop, -/// } -/// -/// unsafe impl Wrapper for Example { -/// type Wrapped = String; -/// } -/// ``` -/// -/// # Safety -/// -/// `Self` must be a `#[repr(transparent)]` wrapper for the `Wrapped` type, -/// whether directly or indirectly. -/// -/// # Methods -/// -/// By convention, types that implement Wrapper also implement the following -/// methods: -/// -/// ```ignore -/// pub const unsafe fn from_raw<'a>(value: *mut Self::Wrapped) -> &'a Self; -/// pub const unsafe fn as_mut_ptr(&self) -> *mut Self::Wrapped; -/// pub const unsafe fn as_ptr(&self) -> *const Self::Wrapped; -/// pub const unsafe fn raw_get(slot: *mut Self) -> *const Self::Wrapped; -/// ``` -/// -/// They are not defined here to allow them to be `const`. -pub unsafe trait Wrapper { - type Wrapped; -} - -unsafe impl Wrapper for Opaque { - type Wrapped = T; -} diff --git a/rust/qemu-api/src/chardev.rs b/rust/qemu-api/src/chardev.rs index cb27be5256..5a351dcecb 100644 --- a/rust/qemu-api/src/chardev.rs +++ b/rust/qemu-api/src/chardev.rs @@ -18,10 +18,11 @@ use std::{ slice, }; +use common::{callbacks::FnCall, errno, Opaque}; + use crate::{ bindings, - callbacks::FnCall, - cell::{BqlRefMut, Opaque}, + cell::{BqlRefCell, BqlRefMut}, prelude::*, }; diff --git a/rust/qemu-api/src/errno.rs b/rust/qemu-api/src/errno.rs deleted file mode 100644 index 507850fe33..0000000000 --- a/rust/qemu-api/src/errno.rs +++ /dev/null @@ -1,354 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0-or-later - -//! Utility functions to convert `errno` to and from -//! [`io::Error`]/[`io::Result`] -//! -//! QEMU C functions often have a "positive success/negative `errno`" calling -//! convention. This module provides functions to portably convert an integer -//! into an [`io::Result`] and back. - -use std::{ - convert::{self, TryFrom}, - io::{self, ErrorKind}, -}; - -/// An `errno` value that can be converted into an [`io::Error`] -pub struct Errno(pub u16); - -// On Unix, from_raw_os_error takes an errno value and OS errors -// are printed using strerror. On Windows however it takes a -// GetLastError() value; therefore we need to convert errno values -// into io::Error by hand. This is the same mapping that the -// standard library uses to retrieve the kind of OS errors -// (`std::sys::pal::unix::decode_error_kind`). -impl From for ErrorKind { - fn from(value: Errno) -> ErrorKind { - use ErrorKind::*; - let Errno(errno) = value; - match i32::from(errno) { - libc::EPERM | libc::EACCES => PermissionDenied, - libc::ENOENT => NotFound, - libc::EINTR => Interrupted, - x if x == libc::EAGAIN || x == libc::EWOULDBLOCK => WouldBlock, - libc::ENOMEM => OutOfMemory, - libc::EEXIST => AlreadyExists, - libc::EINVAL => InvalidInput, - libc::EPIPE => BrokenPipe, - libc::EADDRINUSE => AddrInUse, - libc::EADDRNOTAVAIL => AddrNotAvailable, - libc::ECONNABORTED => ConnectionAborted, - libc::ECONNREFUSED => ConnectionRefused, - libc::ECONNRESET => ConnectionReset, - libc::ENOTCONN => NotConnected, - libc::ENOTSUP => Unsupported, - libc::ETIMEDOUT => TimedOut, - _ => Other, - } - } -} - -// This is used on Windows for all io::Errors, but also on Unix if the -// io::Error does not have a raw OS error. This is the reversed -// mapping of the above; EIO is returned for unknown ErrorKinds. -impl From for Errno { - fn from(value: io::ErrorKind) -> Errno { - use ErrorKind::*; - let errno = match value { - // can be both EPERM or EACCES :( pick one - PermissionDenied => libc::EPERM, - NotFound => libc::ENOENT, - Interrupted => libc::EINTR, - WouldBlock => libc::EAGAIN, - OutOfMemory => libc::ENOMEM, - AlreadyExists => libc::EEXIST, - InvalidInput => libc::EINVAL, - BrokenPipe => libc::EPIPE, - AddrInUse => libc::EADDRINUSE, - AddrNotAvailable => libc::EADDRNOTAVAIL, - ConnectionAborted => libc::ECONNABORTED, - ConnectionRefused => libc::ECONNREFUSED, - ConnectionReset => libc::ECONNRESET, - NotConnected => libc::ENOTCONN, - Unsupported => libc::ENOTSUP, - TimedOut => libc::ETIMEDOUT, - _ => libc::EIO, - }; - Errno(errno as u16) - } -} - -impl From for io::Error { - #[cfg(unix)] - fn from(value: Errno) -> io::Error { - let Errno(errno) = value; - io::Error::from_raw_os_error(errno.into()) - } - - #[cfg(windows)] - fn from(value: Errno) -> io::Error { - let error_kind: ErrorKind = value.into(); - error_kind.into() - } -} - -impl From for Errno { - fn from(value: io::Error) -> Errno { - if cfg!(unix) { - if let Some(errno) = value.raw_os_error() { - return Errno(u16::try_from(errno).unwrap()); - } - } - value.kind().into() - } -} - -impl From for Errno { - fn from(_value: convert::Infallible) -> Errno { - panic!("unreachable") - } -} - -/// Internal traits; used to enable [`into_io_result`] and [`into_neg_errno`] -/// for the "right" set of types. -mod traits { - use super::Errno; - - /// A signed type that can be converted into an - /// [`io::Result`](std::io::Result) - pub trait GetErrno { - /// Unsigned variant of `Self`, used as the type for the `Ok` case. - type Out; - - /// Return `Ok(self)` if positive, `Err(Errno(-self))` if negative - fn into_errno_result(self) -> Result; - } - - /// A type that can be taken out of an [`io::Result`](std::io::Result) and - /// converted into "positive success/negative `errno`" convention. - pub trait MergeErrno { - /// Signed variant of `Self`, used as the return type of - /// [`into_neg_errno`](super::into_neg_errno). - type Out: From + std::ops::Neg; - - /// Return `self`, asserting that it is in range - fn map_ok(self) -> Self::Out; - } - - macro_rules! get_errno { - ($t:ty, $out:ty) => { - impl GetErrno for $t { - type Out = $out; - fn into_errno_result(self) -> Result { - match self { - 0.. => Ok(self as $out), - -65535..=-1 => Err(Errno(-self as u16)), - _ => panic!("{self} is not a negative errno"), - } - } - } - }; - } - - get_errno!(i32, u32); - get_errno!(i64, u64); - get_errno!(isize, usize); - - macro_rules! merge_errno { - ($t:ty, $out:ty) => { - impl MergeErrno for $t { - type Out = $out; - fn map_ok(self) -> Self::Out { - self.try_into().unwrap() - } - } - }; - } - - merge_errno!(u8, i32); - merge_errno!(u16, i32); - merge_errno!(u32, i32); - merge_errno!(u64, i64); - - impl MergeErrno for () { - type Out = i32; - fn map_ok(self) -> i32 { - 0 - } - } -} - -use traits::{GetErrno, MergeErrno}; - -/// Convert an integer value into a [`io::Result`]. -/// -/// Positive values are turned into an `Ok` result; negative values -/// are interpreted as negated `errno` and turned into an `Err`. -/// -/// ``` -/// # use qemu_api::errno::into_io_result; -/// # use std::io::ErrorKind; -/// let ok = into_io_result(1i32).unwrap(); -/// assert_eq!(ok, 1u32); -/// -/// let err = into_io_result(-1i32).unwrap_err(); // -EPERM -/// assert_eq!(err.kind(), ErrorKind::PermissionDenied); -/// ``` -/// -/// # Panics -/// -/// Since the result is an unsigned integer, negative values must -/// be close to 0; values that are too far away are considered -/// likely overflows and will panic: -/// -/// ```should_panic -/// # use qemu_api::errno::into_io_result; -/// # #[allow(dead_code)] -/// let err = into_io_result(-0x1234_5678i32); // panic -/// ``` -pub fn into_io_result(value: T) -> io::Result { - value.into_errno_result().map_err(Into::into) -} - -/// Convert a [`Result`] into an integer value, using negative `errno` -/// values to report errors. -/// -/// ``` -/// # use qemu_api::errno::into_neg_errno; -/// # use std::io::{self, ErrorKind}; -/// let ok: io::Result<()> = Ok(()); -/// assert_eq!(into_neg_errno(ok), 0); -/// -/// let err: io::Result<()> = Err(ErrorKind::InvalidInput.into()); -/// assert_eq!(into_neg_errno(err), -22); // -EINVAL -/// ``` -/// -/// Since this module also provides the ability to convert [`io::Error`] -/// to an `errno` value, [`io::Result`] is the most commonly used type -/// for the argument of this function: -/// -/// # Panics -/// -/// Since the result is a signed integer, integer `Ok` values must remain -/// positive: -/// -/// ```should_panic -/// # use qemu_api::errno::into_neg_errno; -/// # use std::io; -/// let err: io::Result = Ok(0x8899_AABB); -/// into_neg_errno(err) // panic -/// # ; -/// ``` -pub fn into_neg_errno>(value: Result) -> T::Out { - match value { - Ok(x) => x.map_ok(), - Err(err) => -T::Out::from(err.into().0), - } -} - -#[cfg(test)] -mod tests { - use std::io::ErrorKind; - - use super::*; - use crate::assert_match; - - #[test] - pub fn test_from_u8() { - let ok: io::Result<_> = Ok(42u8); - assert_eq!(into_neg_errno(ok), 42); - - let err: io::Result = Err(io::ErrorKind::PermissionDenied.into()); - assert_eq!(into_neg_errno(err), -1); - - if cfg!(unix) { - let os_err: io::Result = Err(io::Error::from_raw_os_error(10)); - assert_eq!(into_neg_errno(os_err), -10); - } - } - - #[test] - pub fn test_from_u16() { - let ok: io::Result<_> = Ok(1234u16); - assert_eq!(into_neg_errno(ok), 1234); - - let err: io::Result = Err(io::ErrorKind::PermissionDenied.into()); - assert_eq!(into_neg_errno(err), -1); - - if cfg!(unix) { - let os_err: io::Result = Err(io::Error::from_raw_os_error(10)); - assert_eq!(into_neg_errno(os_err), -10); - } - } - - #[test] - pub fn test_i32() { - assert_match!(into_io_result(1234i32), Ok(1234)); - - let err = into_io_result(-1i32).unwrap_err(); - #[cfg(unix)] - assert_match!(err.raw_os_error(), Some(1)); - assert_match!(err.kind(), ErrorKind::PermissionDenied); - } - - #[test] - pub fn test_from_u32() { - let ok: io::Result<_> = Ok(1234u32); - assert_eq!(into_neg_errno(ok), 1234); - - let err: io::Result = Err(io::ErrorKind::PermissionDenied.into()); - assert_eq!(into_neg_errno(err), -1); - - if cfg!(unix) { - let os_err: io::Result = Err(io::Error::from_raw_os_error(10)); - assert_eq!(into_neg_errno(os_err), -10); - } - } - - #[test] - pub fn test_i64() { - assert_match!(into_io_result(1234i64), Ok(1234)); - - let err = into_io_result(-22i64).unwrap_err(); - #[cfg(unix)] - assert_match!(err.raw_os_error(), Some(22)); - assert_match!(err.kind(), ErrorKind::InvalidInput); - } - - #[test] - pub fn test_from_u64() { - let ok: io::Result<_> = Ok(1234u64); - assert_eq!(into_neg_errno(ok), 1234); - - let err: io::Result = Err(io::ErrorKind::InvalidInput.into()); - assert_eq!(into_neg_errno(err), -22); - - if cfg!(unix) { - let os_err: io::Result = Err(io::Error::from_raw_os_error(6)); - assert_eq!(into_neg_errno(os_err), -6); - } - } - - #[test] - pub fn test_isize() { - assert_match!(into_io_result(1234isize), Ok(1234)); - - let err = into_io_result(-4isize).unwrap_err(); - #[cfg(unix)] - assert_match!(err.raw_os_error(), Some(4)); - assert_match!(err.kind(), ErrorKind::Interrupted); - } - - #[test] - pub fn test_from_unit() { - let ok: io::Result<_> = Ok(()); - assert_eq!(into_neg_errno(ok), 0); - - let err: io::Result<()> = Err(io::ErrorKind::OutOfMemory.into()); - assert_eq!(into_neg_errno(err), -12); - - if cfg!(unix) { - let os_err: io::Result<()> = Err(io::Error::from_raw_os_error(2)); - assert_eq!(into_neg_errno(os_err), -2); - } - } -} diff --git a/rust/qemu-api/src/error.rs b/rust/qemu-api/src/error.rs index e114fc4178..8bac3cbec8 100644 --- a/rust/qemu-api/src/error.rs +++ b/rust/qemu-api/src/error.rs @@ -316,10 +316,11 @@ mod tests { use std::ffi::CStr; use anyhow::anyhow; + use common::assert_match; use foreign::OwnedPointer; use super::*; - use crate::{assert_match, bindings}; + use crate::bindings; #[track_caller] fn error_for_test(msg: &CStr) -> OwnedPointer { diff --git a/rust/qemu-api/src/irq.rs b/rust/qemu-api/src/irq.rs index 1526e6f63a..ea6b32848c 100644 --- a/rust/qemu-api/src/irq.rs +++ b/rust/qemu-api/src/irq.rs @@ -10,9 +10,10 @@ use std::{ ptr, }; +use common::Opaque; + use crate::{ bindings::{self, qemu_set_irq}, - cell::Opaque, prelude::*, qom::ObjectClass, }; diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs index daa2493bb6..6232e39e71 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -13,12 +13,8 @@ pub mod bindings; #[rustfmt::skip] pub mod prelude; -pub mod assertions; -pub mod bitops; -pub mod callbacks; pub mod cell; pub mod chardev; -pub mod errno; pub mod error; pub mod irq; pub mod log; @@ -28,9 +24,7 @@ pub mod qdev; pub mod qom; pub mod sysbus; pub mod timer; -pub mod uninit; pub mod vmstate; -pub mod zeroable; // Allow proc-macros to refer to `::qemu_api` inside the `qemu_api` crate (this // crate). diff --git a/rust/qemu-api/src/log.rs b/rust/qemu-api/src/log.rs index a441b8c1f2..d07f6272dc 100644 --- a/rust/qemu-api/src/log.rs +++ b/rust/qemu-api/src/log.rs @@ -8,7 +8,9 @@ use std::{ ptr::NonNull, }; -use crate::{bindings, errno}; +use common::errno; + +use crate::bindings; #[repr(u32)] /// Represents specific error categories within QEMU's logging system. diff --git a/rust/qemu-api/src/memory.rs b/rust/qemu-api/src/memory.rs index e40fad6cf1..f790cb5fd2 100644 --- a/rust/qemu-api/src/memory.rs +++ b/rust/qemu-api/src/memory.rs @@ -10,14 +10,11 @@ use std::{ }; pub use bindings::{hwaddr, MemTxAttrs}; +use common::{callbacks::FnCall, uninit::MaybeUninitField, zeroable::Zeroable, Opaque}; use crate::{ bindings::{self, device_endian, memory_region_init_io}, - callbacks::FnCall, - cell::Opaque, prelude::*, - uninit::MaybeUninitField, - zeroable::Zeroable, }; pub struct MemoryRegionOps( diff --git a/rust/qemu-api/src/prelude.rs b/rust/qemu-api/src/prelude.rs index 8f9e23ee2c..dcfe71497f 100644 --- a/rust/qemu-api/src/prelude.rs +++ b/rust/qemu-api/src/prelude.rs @@ -4,13 +4,9 @@ //! Commonly used traits and types for QEMU. -pub use crate::bitops::IntegerExt; - pub use crate::cell::BqlCell; pub use crate::cell::BqlRefCell; -pub use crate::errno; - pub use crate::log_mask_ln; pub use crate::qdev::DeviceMethods; @@ -19,8 +15,8 @@ pub use crate::qom::InterfaceType; pub use crate::qom::IsA; pub use crate::qom::Object; pub use crate::qom::ObjectCast; -pub use crate::qom::ObjectDeref; pub use crate::qom::ObjectClassMethods; +pub use crate::qom::ObjectDeref; pub use crate::qom::ObjectMethods; pub use crate::qom::ObjectType; diff --git a/rust/qemu-api/src/qdev.rs b/rust/qemu-api/src/qdev.rs index e2b4121cac..8be125fae4 100644 --- a/rust/qemu-api/src/qdev.rs +++ b/rust/qemu-api/src/qdev.rs @@ -10,11 +10,11 @@ use std::{ }; pub use bindings::{ClockEvent, DeviceClass, Property, ResetType}; +use common::{callbacks::FnCall, Opaque}; use crate::{ bindings::{self, qdev_init_gpio_in, qdev_init_gpio_out, ResettableClass}, - callbacks::FnCall, - cell::{bql_locked, Opaque}, + cell::bql_locked, chardev::Chardev, error::{Error, Result}, impl_vmstate_c_struct, @@ -246,7 +246,7 @@ macro_rules! define_property { bitnr: $bitnr, set_default: true, defval: $crate::bindings::Property__bindgen_ty_1 { u: $defval as u64 }, - ..$crate::zeroable::Zeroable::ZERO + ..::common::zeroable::Zeroable::ZERO } }; ($name:expr, $state:ty, $field:ident, $prop:expr, $type:ty, default = $defval:expr$(,)*) => { @@ -257,7 +257,7 @@ macro_rules! define_property { offset: ::std::mem::offset_of!($state, $field) as isize, set_default: true, defval: $crate::bindings::Property__bindgen_ty_1 { u: $defval as u64 }, - ..$crate::zeroable::Zeroable::ZERO + ..::common::zeroable::Zeroable::ZERO } }; ($name:expr, $state:ty, $field:ident, $prop:expr, $type:ty$(,)*) => { @@ -267,7 +267,7 @@ macro_rules! define_property { info: $prop, offset: ::std::mem::offset_of!($state, $field) as isize, set_default: false, - ..$crate::zeroable::Zeroable::ZERO + ..::common::zeroable::Zeroable::ZERO } }; } diff --git a/rust/qemu-api/src/qom.rs b/rust/qemu-api/src/qom.rs index 12c6fc6752..49b4f03ccf 100644 --- a/rust/qemu-api/src/qom.rs +++ b/rust/qemu-api/src/qom.rs @@ -102,13 +102,14 @@ use std::{ }; pub use bindings::ObjectClass; +use common::Opaque; use crate::{ bindings::{ self, object_class_dynamic_cast, object_dynamic_cast, object_get_class, object_get_typename, object_new, object_ref, object_unref, TypeInfo, }, - cell::{bql_locked, Opaque}, + cell::bql_locked, impl_vmstate_pointer, }; diff --git a/rust/qemu-api/src/sysbus.rs b/rust/qemu-api/src/sysbus.rs index e92502a8fe..4a5b4cbbf6 100644 --- a/rust/qemu-api/src/sysbus.rs +++ b/rust/qemu-api/src/sysbus.rs @@ -7,10 +7,11 @@ use std::{ffi::CStr, ptr::addr_of_mut}; pub use bindings::SysBusDeviceClass; +use common::Opaque; use crate::{ bindings, - cell::{bql_locked, Opaque}, + cell::bql_locked, irq::{IRQState, InterruptSource}, memory::MemoryRegion, prelude::*, diff --git a/rust/qemu-api/src/timer.rs b/rust/qemu-api/src/timer.rs index 1e639eaf22..383e1a6e77 100644 --- a/rust/qemu-api/src/timer.rs +++ b/rust/qemu-api/src/timer.rs @@ -7,10 +7,10 @@ use std::{ pin::Pin, }; -use crate::{ - bindings::{self, qemu_clock_get_ns, timer_del, timer_init_full, timer_mod, QEMUClockType}, - callbacks::FnCall, - cell::Opaque, +use common::{callbacks::FnCall, Opaque}; + +use crate::bindings::{ + self, qemu_clock_get_ns, timer_del, timer_init_full, timer_mod, QEMUClockType, }; /// A safe wrapper around [`bindings::QEMUTimer`]. diff --git a/rust/qemu-api/src/uninit.rs b/rust/qemu-api/src/uninit.rs deleted file mode 100644 index b0a829729d..0000000000 --- a/rust/qemu-api/src/uninit.rs +++ /dev/null @@ -1,85 +0,0 @@ -//! Access fields of a [`MaybeUninit`] - -use std::{ - mem::MaybeUninit, - ops::{Deref, DerefMut}, -}; - -pub struct MaybeUninitField<'a, T, U> { - parent: &'a mut MaybeUninit, - child: *mut U, -} - -impl<'a, T, U> MaybeUninitField<'a, T, U> { - #[doc(hidden)] - pub const fn new(parent: &'a mut MaybeUninit, child: *mut U) -> Self { - MaybeUninitField { parent, child } - } - - /// Return a constant pointer to the containing object of the field. - /// - /// Because the `MaybeUninitField` remembers the containing object, - /// it is possible to use it in foreign APIs that initialize the - /// child. - pub const fn parent(f: &Self) -> *const T { - f.parent.as_ptr() - } - - /// Return a mutable pointer to the containing object. - /// - /// Because the `MaybeUninitField` remembers the containing object, - /// it is possible to use it in foreign APIs that initialize the - /// child. - pub const fn parent_mut(f: &mut Self) -> *mut T { - f.parent.as_mut_ptr() - } -} - -impl<'a, T, U> Deref for MaybeUninitField<'a, T, U> { - type Target = MaybeUninit; - - fn deref(&self) -> &MaybeUninit { - // SAFETY: self.child was obtained by dereferencing a valid mutable - // reference; the content of the memory may be invalid or uninitialized - // but MaybeUninit<_> makes no assumption on it - unsafe { &*(self.child.cast()) } - } -} - -impl<'a, T, U> DerefMut for MaybeUninitField<'a, T, U> { - fn deref_mut(&mut self) -> &mut MaybeUninit { - // SAFETY: self.child was obtained by dereferencing a valid mutable - // reference; the content of the memory may be invalid or uninitialized - // but MaybeUninit<_> makes no assumption on it - unsafe { &mut *(self.child.cast()) } - } -} - -/// ``` -/// #[derive(Debug)] -/// struct S { -/// x: u32, -/// y: u32, -/// } -/// -/// # use std::mem::MaybeUninit; -/// # use qemu_api::{assert_match, uninit_field_mut}; -/// -/// let mut s: MaybeUninit = MaybeUninit::zeroed(); -/// uninit_field_mut!(s, x).write(5); -/// let s = unsafe { s.assume_init() }; -/// assert_match!(s, S { x: 5, y: 0 }); -/// ``` -#[macro_export] -macro_rules! uninit_field_mut { - ($container:expr, $($field:tt)+) => {{ - let container__: &mut ::std::mem::MaybeUninit<_> = &mut $container; - let container_ptr__ = container__.as_mut_ptr(); - - // SAFETY: the container is not used directly, only through a MaybeUninit<>, - // so the safety is delegated to the caller and to final invocation of - // assume_init() - let target__ = unsafe { std::ptr::addr_of_mut!((*container_ptr__).$($field)+) }; - $crate::uninit::MaybeUninitField::new(container__, target__) - }}; -} diff --git a/rust/qemu-api/src/vmstate.rs b/rust/qemu-api/src/vmstate.rs index ce42b031bc..06aac3a73f 100644 --- a/rust/qemu-api/src/vmstate.rs +++ b/rust/qemu-api/src/vmstate.rs @@ -35,14 +35,15 @@ use std::{ ptr::{addr_of, NonNull}, }; -pub use crate::bindings::{MigrationPriority, VMStateField}; -use crate::{ - bindings::{self, VMStateFlags}, +use common::{ callbacks::FnCall, errno::{into_neg_errno, Errno}, - zeroable::Zeroable, + Zeroable, }; +use crate::bindings::{self, VMStateFlags}; +pub use crate::bindings::{MigrationPriority, VMStateField}; + /// This macro is used to call a function with a generic argument bound /// to the type of a field. The function must take a /// [`PhantomData`]`` argument; `T` is the type of @@ -271,7 +272,7 @@ macro_rules! impl_vmstate_transparent { impl_vmstate_transparent!(std::cell::Cell where T: VMState); impl_vmstate_transparent!(std::cell::UnsafeCell where T: VMState); impl_vmstate_transparent!(std::pin::Pin where T: VMState); -impl_vmstate_transparent!(crate::cell::Opaque where T: VMState); +impl_vmstate_transparent!(::common::Opaque where T: VMState); #[macro_export] macro_rules! impl_vmstate_bitsized { @@ -324,7 +325,7 @@ macro_rules! impl_vmstate_c_struct { vmsd: ::std::ptr::addr_of!($vmsd), size: ::std::mem::size_of::<$type>(), flags: $crate::bindings::VMStateFlags::VMS_STRUCT, - ..$crate::zeroable::Zeroable::ZERO + ..common::zeroable::Zeroable::ZERO }; } }; @@ -367,7 +368,7 @@ macro_rules! vmstate_unused { size: $size, info: unsafe { ::core::ptr::addr_of!($crate::bindings::vmstate_info_unused_buffer) }, flags: $crate::bindings::VMStateFlags::VMS_BUFFER, - ..$crate::zeroable::Zeroable::ZERO + ..::common::Zeroable::ZERO } }}; } @@ -390,7 +391,7 @@ pub type VMSFieldExistCb = unsafe extern "C" fn( #[macro_export] macro_rules! vmstate_exist_fn { ($struct_name:ty, $test_fn:expr) => {{ - const fn test_cb_builder__ $crate::callbacks::FnCall<(&'a T, u8), bool>>( + const fn test_cb_builder__ ::common::callbacks::FnCall<(&'a T, u8), bool>>( _phantom: ::core::marker::PhantomData, ) -> $crate::vmstate::VMSFieldExistCb { const { assert!(F::IS_SOME) }; @@ -414,7 +415,7 @@ macro_rules! vmstate_fields { $($field),*, $crate::bindings::VMStateField { flags: $crate::bindings::VMStateFlags::VMS_END, - ..$crate::zeroable::Zeroable::ZERO + ..::common::zeroable::Zeroable::ZERO } ]; _FIELDS.as_ptr() @@ -433,7 +434,7 @@ macro_rules! vmstate_validate { | $crate::bindings::VMStateFlags::VMS_ARRAY.0, ), num: 0, // 0 elements: no data, only run test_fn callback - ..$crate::zeroable::Zeroable::ZERO + ..::common::zeroable::Zeroable::ZERO } }; } @@ -455,7 +456,7 @@ macro_rules! impl_vmstate_struct { vmsd: ::core::ptr::addr_of!(*VMSD), size: ::core::mem::size_of::<$type>(), flags: $crate::bindings::VMStateFlags::VMS_STRUCT, - ..$crate::zeroable::Zeroable::ZERO + ..common::Zeroable::ZERO } }; } diff --git a/rust/qemu-api/src/zeroable.rs b/rust/qemu-api/src/zeroable.rs deleted file mode 100644 index d8239d0856..0000000000 --- a/rust/qemu-api/src/zeroable.rs +++ /dev/null @@ -1,37 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0-or-later - -//! Defines a trait for structs that can be safely initialized with zero bytes. - -/// Encapsulates the requirement that -/// `MaybeUninit::::zeroed().assume_init()` does not cause undefined -/// behavior. -/// -/// # Safety -/// -/// Do not add this trait to a type unless all-zeroes is a valid value for the -/// type. In particular, raw pointers can be zero, but references and -/// `NonNull` cannot. -pub unsafe trait Zeroable: Default { - /// Return a value of Self whose memory representation consists of all - /// zeroes, with the possible exclusion of padding bytes. - const ZERO: Self = unsafe { ::core::mem::MaybeUninit::::zeroed().assume_init() }; -} - -// bindgen does not derive Default here -#[allow(clippy::derivable_impls)] -impl Default for crate::bindings::VMStateFlags { - fn default() -> Self { - Self(0) - } -} - -unsafe impl Zeroable for crate::bindings::Property__bindgen_ty_1 {} -unsafe impl Zeroable for crate::bindings::Property {} -unsafe impl Zeroable for crate::bindings::VMStateFlags {} -unsafe impl Zeroable for crate::bindings::VMStateField {} -unsafe impl Zeroable for crate::bindings::VMStateDescription {} -unsafe impl Zeroable for crate::bindings::MemoryRegionOps__bindgen_ty_1 {} -unsafe impl Zeroable for crate::bindings::MemoryRegionOps__bindgen_ty_2 {} -unsafe impl Zeroable for crate::bindings::MemoryRegionOps {} -unsafe impl Zeroable for crate::bindings::MemTxAttrs {} -unsafe impl Zeroable for crate::bindings::CharBackend {} diff --git a/rust/qemu-api/tests/vmstate_tests.rs b/rust/qemu-api/tests/vmstate_tests.rs index 2c0670ba0e..d9e5bcc498 100644 --- a/rust/qemu-api/tests/vmstate_tests.rs +++ b/rust/qemu-api/tests/vmstate_tests.rs @@ -9,12 +9,13 @@ use std::{ slice, }; +use common::Opaque; use qemu_api::{ bindings::{ vmstate_info_bool, vmstate_info_int32, vmstate_info_int64, vmstate_info_int8, vmstate_info_uint64, vmstate_info_uint8, vmstate_info_unused_buffer, VMStateFlags, }, - cell::{BqlCell, Opaque}, + cell::BqlCell, impl_vmstate_forward, impl_vmstate_struct, vmstate::{VMStateDescription, VMStateDescriptionBuilder, VMStateField}, vmstate_fields, vmstate_of, vmstate_unused, vmstate_validate, -- cgit 1.4.1 From f6b4f0dd9c57079b72ca9ff7569ce4d0dbdcc4d9 Mon Sep 17 00:00:00 2001 From: Marc-André Lureau Date: Mon, 8 Sep 2025 12:49:52 +0200 Subject: rust: split "bql" crate MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Unfortunately, an example had to be compile-time disabled, since it relies on higher level crates (qdev, irq etc). The alternative is probably to move that code to an example in qemu-api or elsewere and make a link to it, or include_str. Signed-off-by: Marc-André Lureau Link: https://lore.kernel.org/r/20250827104147.717203-12-marcandre.lureau@redhat.com Reviewed-by: Zhao Liu Signed-off-by: Paolo Bonzini --- MAINTAINERS | 1 + rust/Cargo.lock | 10 + rust/Cargo.toml | 1 + rust/bql/Cargo.toml | 23 + rust/bql/build.rs | 1 + rust/bql/meson.build | 52 +++ rust/bql/src/bindings.rs | 25 + rust/bql/src/cell.rs | 850 ++++++++++++++++++++++++++++++++++ rust/bql/src/lib.rs | 29 ++ rust/bql/wrapper.h | 27 ++ rust/common/src/opaque.rs | 4 +- rust/hw/char/pl011/Cargo.toml | 1 + rust/hw/char/pl011/meson.build | 1 + rust/hw/char/pl011/src/device.rs | 1 + rust/hw/timer/hpet/Cargo.toml | 1 + rust/hw/timer/hpet/meson.build | 1 + rust/hw/timer/hpet/src/device.rs | 2 +- rust/hw/timer/hpet/src/fw_cfg.rs | 5 +- rust/meson.build | 1 + rust/migration/src/vmstate.rs | 4 +- rust/qemu-api/Cargo.toml | 5 +- rust/qemu-api/meson.build | 18 +- rust/qemu-api/src/cell.rs | 874 ----------------------------------- rust/qemu-api/src/chardev.rs | 17 +- rust/qemu-api/src/irq.rs | 1 + rust/qemu-api/src/lib.rs | 1 - rust/qemu-api/src/prelude.rs | 3 - rust/qemu-api/src/qdev.rs | 5 +- rust/qemu-api/src/qom.rs | 13 +- rust/qemu-api/src/sysbus.rs | 13 +- rust/qemu-api/tests/tests.rs | 4 +- rust/qemu-api/tests/vmstate_tests.rs | 2 +- 32 files changed, 1060 insertions(+), 936 deletions(-) create mode 100644 rust/bql/Cargo.toml create mode 120000 rust/bql/build.rs create mode 100644 rust/bql/meson.build create mode 100644 rust/bql/src/bindings.rs create mode 100644 rust/bql/src/cell.rs create mode 100644 rust/bql/src/lib.rs create mode 100644 rust/bql/wrapper.h delete mode 100644 rust/qemu-api/src/cell.rs (limited to 'rust/qemu-api/src/chardev.rs') diff --git a/MAINTAINERS b/MAINTAINERS index 76dcf6ceb2..a55d5c95d7 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3515,6 +3515,7 @@ F: include/hw/registerfields.h Rust M: Manos Pitsidianakis S: Maintained +F: rust/bql/ F: rust/common/ F: rust/migration/ F: rust/qemu-api diff --git a/rust/Cargo.lock b/rust/Cargo.lock index 048dd74757..73ca9582a5 100644 --- a/rust/Cargo.lock +++ b/rust/Cargo.lock @@ -44,6 +44,13 @@ dependencies = [ "qemu_api_macros", ] +[[package]] +name = "bql" +version = "0.1.0" +dependencies = [ + "migration", +] + [[package]] name = "common" version = "0.1.0" @@ -70,6 +77,7 @@ dependencies = [ name = "hpet" version = "0.1.0" dependencies = [ + "bql", "common", "migration", "qemu_api", @@ -108,6 +116,7 @@ dependencies = [ "bilge", "bilge-impl", "bits", + "bql", "common", "migration", "qemu_api", @@ -151,6 +160,7 @@ dependencies = [ name = "qemu_api" version = "0.1.0" dependencies = [ + "bql", "common", "migration", "qemu_api_macros", diff --git a/rust/Cargo.toml b/rust/Cargo.toml index e0958ef28a..8be90da8ff 100644 --- a/rust/Cargo.toml +++ b/rust/Cargo.toml @@ -2,6 +2,7 @@ resolver = "2" members = [ "bits", + "bql", "common", "migration", "qemu-api-macros", diff --git a/rust/bql/Cargo.toml b/rust/bql/Cargo.toml new file mode 100644 index 0000000000..1041bd4ea9 --- /dev/null +++ b/rust/bql/Cargo.toml @@ -0,0 +1,23 @@ +[package] +name = "bql" +version = "0.1.0" +description = "Rust bindings for QEMU/BQL" +resolver = "2" +publish = false + +authors.workspace = true +edition.workspace = true +homepage.workspace = true +license.workspace = true +repository.workspace = true +rust-version.workspace = true + +[dependencies] +migration = { path = "../migration" } + +[features] +default = ["debug_cell"] +debug_cell = [] + +[lints] +workspace = true diff --git a/rust/bql/build.rs b/rust/bql/build.rs new file mode 120000 index 0000000000..71a3167885 --- /dev/null +++ b/rust/bql/build.rs @@ -0,0 +1 @@ +../util/build.rs \ No newline at end of file diff --git a/rust/bql/meson.build b/rust/bql/meson.build new file mode 100644 index 0000000000..f369209dfd --- /dev/null +++ b/rust/bql/meson.build @@ -0,0 +1,52 @@ +_bql_cfg = run_command(rustc_args, + '--config-headers', config_host_h, '--features', files('Cargo.toml'), + capture: true, check: true).stdout().strip().splitlines() + +if get_option('debug_mutex') + _bql_cfg += ['--cfg', 'feature="debug_cell"'] +endif + +# +# TODO: Remove this comment when the clang/libclang mismatch issue is solved. +# +# Rust bindings generation with `bindgen` might fail in some cases where the +# detected `libclang` does not match the expected `clang` version/target. In +# this case you must pass the path to `clang` and `libclang` to your build +# command invocation using the environment variables CLANG_PATH and +# LIBCLANG_PATH +_bql_bindings_inc_rs = rust.bindgen( + input: 'wrapper.h', + dependencies: common_ss.all_dependencies(), + output: 'bindings.inc.rs', + include_directories: bindings_incdir, + bindgen_version: ['>=0.60.0'], + args: bindgen_args_common, +) + +_bql_rs = static_library( + 'bql', + structured_sources( + [ + 'src/lib.rs', + 'src/bindings.rs', + 'src/cell.rs', + ], + {'.': _bql_bindings_inc_rs} + ), + override_options: ['rust_std=2021', 'build.rust_std=2021'], + rust_abi: 'rust', + rust_args: _bql_cfg, + link_with: [_migration_rs], +) + +bql_rs = declare_dependency(link_with: [_bql_rs], + dependencies: [qemuutil]) + +# Doctests are essentially integration tests, so they need the same dependencies. +# Note that running them requires the object files for C code, so place them +# in a separate suite that is run by the "build" CI jobs rather than "check". +rust.doctest('rust-bql-rs-doctests', + _bql_rs, + protocol: 'rust', + dependencies: bql_rs, + suite: ['doc', 'rust']) diff --git a/rust/bql/src/bindings.rs b/rust/bql/src/bindings.rs new file mode 100644 index 0000000000..9ffff12cde --- /dev/null +++ b/rust/bql/src/bindings.rs @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#![allow( + dead_code, + improper_ctypes_definitions, + improper_ctypes, + non_camel_case_types, + non_snake_case, + non_upper_case_globals, + unnecessary_transmutes, + unsafe_op_in_unsafe_fn, + clippy::pedantic, + clippy::restriction, + clippy::style, + clippy::missing_const_for_fn, + clippy::ptr_offset_with_cast, + clippy::useless_transmute, + clippy::missing_safety_doc, + clippy::too_many_arguments +)] + +#[cfg(MESON)] +include!("bindings.inc.rs"); + +#[cfg(not(MESON))] +include!(concat!(env!("OUT_DIR"), "/bindings.inc.rs")); diff --git a/rust/bql/src/cell.rs b/rust/bql/src/cell.rs new file mode 100644 index 0000000000..25007427ed --- /dev/null +++ b/rust/bql/src/cell.rs @@ -0,0 +1,850 @@ +// SPDX-License-Identifier: MIT +// +// This file is based on library/core/src/cell.rs from +// Rust 1.82.0. +// +// Permission is hereby granted, free of charge, to any +// person obtaining a copy of this software and associated +// documentation files (the "Software"), to deal in the +// Software without restriction, including without +// limitation the rights to use, copy, modify, merge, +// publish, distribute, sublicense, and/or sell copies of +// the Software, and to permit persons to whom the Software +// is furnished to do so, subject to the following +// conditions: +// +// The above copyright notice and this permission notice +// shall be included in all copies or substantial portions +// of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF +// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED +// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A +// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT +// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY +// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR +// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER +// DEALINGS IN THE SOFTWARE. + +//! QEMU-specific mutable containers +//! +//! Rust memory safety is based on this rule: Given an object `T`, it is only +//! possible to have one of the following: +//! +//! - Having several immutable references (`&T`) to the object (also known as +//! **aliasing**). +//! - Having one mutable reference (`&mut T`) to the object (also known as +//! **mutability**). +//! +//! This is enforced by the Rust compiler. However, there are situations where +//! this rule is not flexible enough. Sometimes it is required to have multiple +//! references to an object and yet mutate it. In particular, QEMU objects +//! usually have their pointer shared with the "outside world very early in +//! their lifetime", for example when they create their +//! [`MemoryRegion`s](crate::bindings::MemoryRegion). Therefore, individual +//! parts of a device must be made mutable in a controlled manner; this module +//! provides the tools to do so. +//! +//! ## Cell types +//! +//! [`BqlCell`] and [`BqlRefCell`] allow doing this via the Big QEMU Lock. +//! While they are essentially the same single-threaded primitives that are +//! available in `std::cell`, the BQL allows them to be used from a +//! multi-threaded context and to share references across threads, while +//! maintaining Rust's safety guarantees. For this reason, unlike +//! their `std::cell` counterparts, `BqlCell` and `BqlRefCell` implement the +//! `Sync` trait. +//! +//! BQL checks are performed in debug builds but can be optimized away in +//! release builds, providing runtime safety during development with no overhead +//! in production. +//! +//! The two provide different ways of handling interior mutability. +//! `BqlRefCell` is best suited for data that is primarily accessed by the +//! device's own methods, where multiple reads and writes can be grouped within +//! a single borrow and a mutable reference can be passed around. Instead, +//! [`BqlCell`] is a better choice when sharing small pieces of data with +//! external code (especially C code), because it provides simple get/set +//! operations that can be used one at a time. +//! +//! Warning: While `BqlCell` and `BqlRefCell` are similar to their `std::cell` +//! counterparts, they are not interchangeable. Using `std::cell` types in +//! QEMU device implementations is usually incorrect and can lead to +//! thread-safety issues. +//! +//! ### Example +//! +//! ```ignore +//! # use bql::BqlRefCell; +//! # use qemu_api::prelude::*; +//! # use qemu_api::{irq::InterruptSource, irq::IRQState}; +//! # use qemu_api::{sysbus::SysBusDevice, qom::Owned, qom::ParentField}; +//! # const N_GPIOS: usize = 8; +//! # struct PL061Registers { /* ... */ } +//! # unsafe impl ObjectType for PL061State { +//! # type Class = ::Class; +//! # const TYPE_NAME: &'static std::ffi::CStr = c"pl061"; +//! # } +//! struct PL061State { +//! parent_obj: ParentField, +//! +//! // Configuration is read-only after initialization +//! pullups: u32, +//! pulldowns: u32, +//! +//! // Single values shared with C code use BqlCell, in this case via InterruptSource +//! out: [InterruptSource; N_GPIOS], +//! interrupt: InterruptSource, +//! +//! // Larger state accessed by device methods uses BqlRefCell or Mutex +//! registers: BqlRefCell, +//! } +//! ``` +//! +//! ### `BqlCell` +//! +//! [`BqlCell`] implements interior mutability by moving values in and out of +//! the cell. That is, an `&mut T` to the inner value can never be obtained as +//! long as the cell is shared. The value itself cannot be directly obtained +//! without copying it, cloning it, or replacing it with something else. This +//! type provides the following methods, all of which can be called only while +//! the BQL is held: +//! +//! - For types that implement [`Copy`], the [`get`](BqlCell::get) method +//! retrieves the current interior value by duplicating it. +//! - For types that implement [`Default`], the [`take`](BqlCell::take) method +//! replaces the current interior value with [`Default::default()`] and +//! returns the replaced value. +//! - All types have: +//! - [`replace`](BqlCell::replace): replaces the current interior value and +//! returns the replaced value. +//! - [`set`](BqlCell::set): this method replaces the interior value, +//! dropping the replaced value. +//! +//! ### `BqlRefCell` +//! +//! [`BqlRefCell`] uses Rust's lifetimes to implement "dynamic borrowing", a +//! process whereby one can claim temporary, exclusive, mutable access to the +//! inner value: +//! +//! ```ignore +//! fn clear_interrupts(&self, val: u32) { +//! // A mutable borrow gives read-write access to the registers +//! let mut regs = self.registers.borrow_mut(); +//! let old = regs.interrupt_status(); +//! regs.update_interrupt_status(old & !val); +//! } +//! ``` +//! +//! Borrows for `BqlRefCell`s are tracked at _runtime_, unlike Rust's native +//! reference types which are entirely tracked statically, at compile time. +//! Multiple immutable borrows are allowed via [`borrow`](BqlRefCell::borrow), +//! or a single mutable borrow via [`borrow_mut`](BqlRefCell::borrow_mut). The +//! thread will panic if these rules are violated or if the BQL is not held. +use std::{ + cell::{Cell, UnsafeCell}, + cmp::Ordering, + fmt, + marker::PhantomData, + mem, + ops::{Deref, DerefMut}, + ptr::NonNull, +}; + +use migration::impl_vmstate_transparent; + +/// A mutable memory location that is protected by the Big QEMU Lock. +/// +/// # Memory layout +/// +/// `BqlCell` has the same in-memory representation as its inner type `T`. +#[repr(transparent)] +pub struct BqlCell { + value: UnsafeCell, +} + +// SAFETY: Same as for std::sync::Mutex. In the end this *is* a Mutex, +// except it is stored out-of-line +unsafe impl Send for BqlCell {} +unsafe impl Sync for BqlCell {} + +impl Clone for BqlCell { + #[inline] + fn clone(&self) -> BqlCell { + BqlCell::new(self.get()) + } +} + +impl Default for BqlCell { + /// Creates a `BqlCell`, with the `Default` value for T. + #[inline] + fn default() -> BqlCell { + BqlCell::new(Default::default()) + } +} + +impl PartialEq for BqlCell { + #[inline] + fn eq(&self, other: &BqlCell) -> bool { + self.get() == other.get() + } +} + +impl Eq for BqlCell {} + +impl PartialOrd for BqlCell { + #[inline] + fn partial_cmp(&self, other: &BqlCell) -> Option { + self.get().partial_cmp(&other.get()) + } +} + +impl Ord for BqlCell { + #[inline] + fn cmp(&self, other: &BqlCell) -> Ordering { + self.get().cmp(&other.get()) + } +} + +impl From for BqlCell { + /// Creates a new `BqlCell` containing the given value. + fn from(t: T) -> BqlCell { + BqlCell::new(t) + } +} + +impl fmt::Debug for BqlCell { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + self.get().fmt(f) + } +} + +impl fmt::Display for BqlCell { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + self.get().fmt(f) + } +} + +impl BqlCell { + /// Creates a new `BqlCell` containing the given value. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlCell; + /// # bql::start_test(); + /// + /// let c = BqlCell::new(5); + /// ``` + #[inline] + pub const fn new(value: T) -> BqlCell { + BqlCell { + value: UnsafeCell::new(value), + } + } + + /// Sets the contained value. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlCell; + /// # bql::start_test(); + /// + /// let c = BqlCell::new(5); + /// + /// c.set(10); + /// ``` + #[inline] + pub fn set(&self, val: T) { + self.replace(val); + } + + /// Replaces the contained value with `val`, and returns the old contained + /// value. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlCell; + /// # bql::start_test(); + /// + /// let cell = BqlCell::new(5); + /// assert_eq!(cell.get(), 5); + /// assert_eq!(cell.replace(10), 5); + /// assert_eq!(cell.get(), 10); + /// ``` + #[inline] + pub fn replace(&self, val: T) -> T { + assert!(crate::is_locked()); + // SAFETY: This can cause data races if called from multiple threads, + // but it won't happen as long as C code accesses the value + // under BQL protection only. + mem::replace(unsafe { &mut *self.value.get() }, val) + } + + /// Unwraps the value, consuming the cell. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlCell; + /// # bql::start_test(); + /// + /// let c = BqlCell::new(5); + /// let five = c.into_inner(); + /// + /// assert_eq!(five, 5); + /// ``` + pub fn into_inner(self) -> T { + assert!(crate::is_locked()); + self.value.into_inner() + } +} + +impl BqlCell { + /// Returns a copy of the contained value. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlCell; + /// # bql::start_test(); + /// + /// let c = BqlCell::new(5); + /// + /// let five = c.get(); + /// ``` + #[inline] + pub fn get(&self) -> T { + assert!(crate::is_locked()); + // SAFETY: This can cause data races if called from multiple threads, + // but it won't happen as long as C code accesses the value + // under BQL protection only. + unsafe { *self.value.get() } + } +} + +impl BqlCell { + /// Returns a raw pointer to the underlying data in this cell. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlCell; + /// # bql::start_test(); + /// + /// let c = BqlCell::new(5); + /// + /// let ptr = c.as_ptr(); + /// ``` + #[inline] + pub const fn as_ptr(&self) -> *mut T { + self.value.get() + } +} + +impl BqlCell { + /// Takes the value of the cell, leaving `Default::default()` in its place. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlCell; + /// # bql::start_test(); + /// + /// let c = BqlCell::new(5); + /// let five = c.take(); + /// + /// assert_eq!(five, 5); + /// assert_eq!(c.into_inner(), 0); + /// ``` + pub fn take(&self) -> T { + self.replace(Default::default()) + } +} + +impl_vmstate_transparent!(crate::cell::BqlCell where T: VMState); + +/// A mutable memory location with dynamically checked borrow rules, +/// protected by the Big QEMU Lock. +/// +/// See the [module-level documentation](self) for more. +/// +/// # Memory layout +/// +/// `BqlRefCell` starts with the same in-memory representation as its +/// inner type `T`. +#[repr(C)] +pub struct BqlRefCell { + // It is important that this is the first field (which is not the case + // for std::cell::BqlRefCell), so that we can use offset_of! on it. + // UnsafeCell and repr(C) both prevent usage of niches. + value: UnsafeCell, + borrow: Cell, + // Stores the location of the earliest currently active borrow. + // This gets updated whenever we go from having zero borrows + // to having a single borrow. When a borrow occurs, this gets included + // in the panic message + #[cfg(feature = "debug_cell")] + borrowed_at: Cell>>, +} + +// Positive values represent the number of `BqlRef` active. Negative values +// represent the number of `BqlRefMut` active. Right now QEMU's implementation +// does not allow to create `BqlRefMut`s that refer to distinct, nonoverlapping +// components of a `BqlRefCell` (e.g., different ranges of a slice). +// +// `BqlRef` and `BqlRefMut` are both two words in size, and so there will likely +// never be enough `BqlRef`s or `BqlRefMut`s in existence to overflow half of +// the `usize` range. Thus, a `BorrowFlag` will probably never overflow or +// underflow. However, this is not a guarantee, as a pathological program could +// repeatedly create and then mem::forget `BqlRef`s or `BqlRefMut`s. Thus, all +// code must explicitly check for overflow and underflow in order to avoid +// unsafety, or at least behave correctly in the event that overflow or +// underflow happens (e.g., see BorrowRef::new). +type BorrowFlag = isize; +const UNUSED: BorrowFlag = 0; + +#[inline(always)] +const fn is_writing(x: BorrowFlag) -> bool { + x < UNUSED +} + +#[inline(always)] +const fn is_reading(x: BorrowFlag) -> bool { + x > UNUSED +} + +impl BqlRefCell { + /// Creates a new `BqlRefCell` containing `value`. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlRefCell; + /// + /// let c = BqlRefCell::new(5); + /// ``` + #[inline] + pub const fn new(value: T) -> BqlRefCell { + BqlRefCell { + value: UnsafeCell::new(value), + borrow: Cell::new(UNUSED), + #[cfg(feature = "debug_cell")] + borrowed_at: Cell::new(None), + } + } +} + +// This ensures the panicking code is outlined from `borrow_mut` for +// `BqlRefCell`. +#[inline(never)] +#[cold] +#[cfg(feature = "debug_cell")] +fn panic_already_borrowed(source: &Cell>>) -> ! { + // If a borrow occurred, then we must already have an outstanding borrow, + // so `borrowed_at` will be `Some` + panic!("already borrowed at {:?}", source.take().unwrap()) +} + +#[inline(never)] +#[cold] +#[cfg(not(feature = "debug_cell"))] +fn panic_already_borrowed() -> ! { + panic!("already borrowed") +} + +impl BqlRefCell { + #[inline] + #[allow(clippy::unused_self)] + fn panic_already_borrowed(&self) -> ! { + #[cfg(feature = "debug_cell")] + { + panic_already_borrowed(&self.borrowed_at) + } + #[cfg(not(feature = "debug_cell"))] + { + panic_already_borrowed() + } + } + + /// Immutably borrows the wrapped value. + /// + /// The borrow lasts until the returned `BqlRef` exits scope. Multiple + /// immutable borrows can be taken out at the same time. + /// + /// # Panics + /// + /// Panics if the value is currently mutably borrowed. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlRefCell; + /// # bql::start_test(); + /// + /// let c = BqlRefCell::new(5); + /// + /// let borrowed_five = c.borrow(); + /// let borrowed_five2 = c.borrow(); + /// ``` + /// + /// An example of panic: + /// + /// ```should_panic + /// use bql::BqlRefCell; + /// # bql::start_test(); + /// + /// let c = BqlRefCell::new(5); + /// + /// let m = c.borrow_mut(); + /// let b = c.borrow(); // this causes a panic + /// ``` + #[inline] + #[track_caller] + pub fn borrow(&self) -> BqlRef<'_, T> { + if let Some(b) = BorrowRef::new(&self.borrow) { + // `borrowed_at` is always the *first* active borrow + if b.borrow.get() == 1 { + #[cfg(feature = "debug_cell")] + self.borrowed_at.set(Some(std::panic::Location::caller())); + } + + crate::block_unlock(true); + + // SAFETY: `BorrowRef` ensures that there is only immutable access + // to the value while borrowed. + let value = unsafe { NonNull::new_unchecked(self.value.get()) }; + BqlRef { value, borrow: b } + } else { + self.panic_already_borrowed() + } + } + + /// Mutably borrows the wrapped value. + /// + /// The borrow lasts until the returned `BqlRefMut` or all `BqlRefMut`s + /// derived from it exit scope. The value cannot be borrowed while this + /// borrow is active. + /// + /// # Panics + /// + /// Panics if the value is currently borrowed. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlRefCell; + /// # bql::start_test(); + /// + /// let c = BqlRefCell::new("hello".to_owned()); + /// + /// *c.borrow_mut() = "bonjour".to_owned(); + /// + /// assert_eq!(&*c.borrow(), "bonjour"); + /// ``` + /// + /// An example of panic: + /// + /// ```should_panic + /// use bql::BqlRefCell; + /// # bql::start_test(); + /// + /// let c = BqlRefCell::new(5); + /// let m = c.borrow(); + /// + /// let b = c.borrow_mut(); // this causes a panic + /// ``` + #[inline] + #[track_caller] + pub fn borrow_mut(&self) -> BqlRefMut<'_, T> { + if let Some(b) = BorrowRefMut::new(&self.borrow) { + #[cfg(feature = "debug_cell")] + { + self.borrowed_at.set(Some(std::panic::Location::caller())); + } + + // SAFETY: this only adjusts a counter + crate::block_unlock(true); + + // SAFETY: `BorrowRefMut` guarantees unique access. + let value = unsafe { NonNull::new_unchecked(self.value.get()) }; + BqlRefMut { + value, + _borrow: b, + marker: PhantomData, + } + } else { + self.panic_already_borrowed() + } + } + + /// Returns a raw pointer to the underlying data in this cell. + /// + /// # Examples + /// + /// ``` + /// use bql::BqlRefCell; + /// + /// let c = BqlRefCell::new(5); + /// + /// let ptr = c.as_ptr(); + /// ``` + #[inline] + pub const fn as_ptr(&self) -> *mut T { + self.value.get() + } +} + +// SAFETY: Same as for std::sync::Mutex. In the end this is a Mutex that is +// stored out-of-line. Even though BqlRefCell includes Cells, they are +// themselves protected by the Big QEMU Lock. Furtheremore, the Big QEMU +// Lock cannot be released while any borrows is active. +unsafe impl Send for BqlRefCell where T: Send {} +unsafe impl Sync for BqlRefCell {} + +impl Clone for BqlRefCell { + /// # Panics + /// + /// Panics if the value is currently mutably borrowed. + #[inline] + #[track_caller] + fn clone(&self) -> BqlRefCell { + BqlRefCell::new(self.borrow().clone()) + } + + /// # Panics + /// + /// Panics if `source` is currently mutably borrowed. + #[inline] + #[track_caller] + fn clone_from(&mut self, source: &Self) { + self.value.get_mut().clone_from(&source.borrow()) + } +} + +impl Default for BqlRefCell { + /// Creates a `BqlRefCell`, with the `Default` value for T. + #[inline] + fn default() -> BqlRefCell { + BqlRefCell::new(Default::default()) + } +} + +impl PartialEq for BqlRefCell { + /// # Panics + /// + /// Panics if the value in either `BqlRefCell` is currently mutably + /// borrowed. + #[inline] + fn eq(&self, other: &BqlRefCell) -> bool { + *self.borrow() == *other.borrow() + } +} + +impl Eq for BqlRefCell {} + +impl PartialOrd for BqlRefCell { + /// # Panics + /// + /// Panics if the value in either `BqlRefCell` is currently mutably + /// borrowed. + #[inline] + fn partial_cmp(&self, other: &BqlRefCell) -> Option { + self.borrow().partial_cmp(&*other.borrow()) + } +} + +impl Ord for BqlRefCell { + /// # Panics + /// + /// Panics if the value in either `BqlRefCell` is currently mutably + /// borrowed. + #[inline] + fn cmp(&self, other: &BqlRefCell) -> Ordering { + self.borrow().cmp(&*other.borrow()) + } +} + +impl From for BqlRefCell { + /// Creates a new `BqlRefCell` containing the given value. + fn from(t: T) -> BqlRefCell { + BqlRefCell::new(t) + } +} + +impl_vmstate_transparent!(crate::cell::BqlRefCell where T: VMState); + +struct BorrowRef<'b> { + borrow: &'b Cell, +} + +impl<'b> BorrowRef<'b> { + #[inline] + fn new(borrow: &'b Cell) -> Option> { + let b = borrow.get().wrapping_add(1); + if !is_reading(b) { + // Incrementing borrow can result in a non-reading value (<= 0) in these cases: + // 1. It was < 0, i.e. there are writing borrows, so we can't allow a read + // borrow due to Rust's reference aliasing rules + // 2. It was isize::MAX (the max amount of reading borrows) and it overflowed + // into isize::MIN (the max amount of writing borrows) so we can't allow an + // additional read borrow because isize can't represent so many read borrows + // (this can only happen if you mem::forget more than a small constant amount + // of `BqlRef`s, which is not good practice) + None + } else { + // Incrementing borrow can result in a reading value (> 0) in these cases: + // 1. It was = 0, i.e. it wasn't borrowed, and we are taking the first read + // borrow + // 2. It was > 0 and < isize::MAX, i.e. there were read borrows, and isize is + // large enough to represent having one more read borrow + borrow.set(b); + Some(BorrowRef { borrow }) + } + } +} + +impl Drop for BorrowRef<'_> { + #[inline] + fn drop(&mut self) { + let borrow = self.borrow.get(); + debug_assert!(is_reading(borrow)); + self.borrow.set(borrow - 1); + crate::block_unlock(false) + } +} + +impl Clone for BorrowRef<'_> { + #[inline] + fn clone(&self) -> Self { + BorrowRef::new(self.borrow).unwrap() + } +} + +/// Wraps a borrowed reference to a value in a `BqlRefCell` box. +/// A wrapper type for an immutably borrowed value from a `BqlRefCell`. +/// +/// See the [module-level documentation](self) for more. +pub struct BqlRef<'b, T: 'b> { + // NB: we use a pointer instead of `&'b T` to avoid `noalias` violations, because a + // `BqlRef` argument doesn't hold immutability for its whole scope, only until it drops. + // `NonNull` is also covariant over `T`, just like we would have with `&T`. + value: NonNull, + borrow: BorrowRef<'b>, +} + +impl Deref for BqlRef<'_, T> { + type Target = T; + + #[inline] + fn deref(&self) -> &T { + // SAFETY: the value is accessible as long as we hold our borrow. + unsafe { self.value.as_ref() } + } +} + +impl<'b, T> BqlRef<'b, T> { + /// Copies a `BqlRef`. + /// + /// The `BqlRefCell` is already immutably borrowed, so this cannot fail. + /// + /// This is an associated function that needs to be used as + /// `BqlRef::clone(...)`. A `Clone` implementation or a method would + /// interfere with the widespread use of `r.borrow().clone()` to clone + /// the contents of a `BqlRefCell`. + #[must_use] + #[inline] + #[allow(clippy::should_implement_trait)] + pub fn clone(orig: &BqlRef<'b, T>) -> BqlRef<'b, T> { + BqlRef { + value: orig.value, + borrow: orig.borrow.clone(), + } + } +} + +impl fmt::Debug for BqlRef<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + (**self).fmt(f) + } +} + +impl fmt::Display for BqlRef<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + (**self).fmt(f) + } +} + +struct BorrowRefMut<'b> { + borrow: &'b Cell, +} + +impl<'b> BorrowRefMut<'b> { + #[inline] + fn new(borrow: &'b Cell) -> Option> { + // There must currently be no existing references when borrow_mut() is + // called, so we explicitly only allow going from UNUSED to UNUSED - 1. + match borrow.get() { + UNUSED => { + borrow.set(UNUSED - 1); + Some(BorrowRefMut { borrow }) + } + _ => None, + } + } +} + +impl Drop for BorrowRefMut<'_> { + #[inline] + fn drop(&mut self) { + let borrow = self.borrow.get(); + debug_assert!(is_writing(borrow)); + self.borrow.set(borrow + 1); + crate::block_unlock(false) + } +} + +/// A wrapper type for a mutably borrowed value from a `BqlRefCell`. +/// +/// See the [module-level documentation](self) for more. +pub struct BqlRefMut<'b, T: 'b> { + // NB: we use a pointer instead of `&'b mut T` to avoid `noalias` violations, because a + // `BqlRefMut` argument doesn't hold exclusivity for its whole scope, only until it drops. + value: NonNull, + _borrow: BorrowRefMut<'b>, + // `NonNull` is covariant over `T`, so we need to reintroduce invariance. + marker: PhantomData<&'b mut T>, +} + +impl Deref for BqlRefMut<'_, T> { + type Target = T; + + #[inline] + fn deref(&self) -> &T { + // SAFETY: the value is accessible as long as we hold our borrow. + unsafe { self.value.as_ref() } + } +} + +impl DerefMut for BqlRefMut<'_, T> { + #[inline] + fn deref_mut(&mut self) -> &mut T { + // SAFETY: the value is accessible as long as we hold our borrow. + unsafe { self.value.as_mut() } + } +} + +impl fmt::Debug for BqlRefMut<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + (**self).fmt(f) + } +} + +impl fmt::Display for BqlRefMut<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + (**self).fmt(f) + } +} diff --git a/rust/bql/src/lib.rs b/rust/bql/src/lib.rs new file mode 100644 index 0000000000..ef08221e9c --- /dev/null +++ b/rust/bql/src/lib.rs @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +mod bindings; +use bindings::{bql_block_unlock, bql_locked, rust_bql_mock_lock}; + +mod cell; +pub use cell::*; + +/// An internal function that is used by doctests. +pub fn start_test() { + // SAFETY: integration tests are run with --test-threads=1, while + // unit tests and doctests are not multithreaded and do not have + // any BQL-protected data. Just set bql_locked to true. + unsafe { + rust_bql_mock_lock(); + } +} + +pub fn is_locked() -> bool { + // SAFETY: the function does nothing but return a thread-local bool + unsafe { bql_locked() } +} + +pub fn block_unlock(increase: bool) { + // SAFETY: this only adjusts a counter + unsafe { + bql_block_unlock(increase); + } +} diff --git a/rust/bql/wrapper.h b/rust/bql/wrapper.h new file mode 100644 index 0000000000..2ef9a96e1d --- /dev/null +++ b/rust/bql/wrapper.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +/* + * This header file is meant to be used as input to the `bindgen` application + * in order to generate C FFI compatible Rust bindings. + */ + +#ifndef __CLANG_STDATOMIC_H +#define __CLANG_STDATOMIC_H +/* + * Fix potential missing stdatomic.h error in case bindgen does not insert the + * correct libclang header paths on its own. We do not use stdatomic.h symbols + * in QEMU code, so it's fine to declare dummy types instead. + */ +typedef enum memory_order { + memory_order_relaxed, + memory_order_consume, + memory_order_acquire, + memory_order_release, + memory_order_acq_rel, + memory_order_seq_cst, +} memory_order; +#endif /* __CLANG_STDATOMIC_H */ + +#include "qemu/osdep.h" + +#include "qemu/main-loop.h" diff --git a/rust/common/src/opaque.rs b/rust/common/src/opaque.rs index d25a5f3ae1..97ed3e8452 100644 --- a/rust/common/src/opaque.rs +++ b/rust/common/src/opaque.rs @@ -69,8 +69,8 @@ //! and only at FFI boundaries. For QEMU-specific types that need interior //! mutability, prefer [`BqlCell`] or [`BqlRefCell`]. //! -//! [`BqlCell`]: ../../qemu_api/cell/struct.BqlCell.html -//! [`BqlRefCell`]: ../../qemu_api/cell/struct.BqlRefCell.html +//! [`BqlCell`]: ../../bql/cell/struct.BqlCell.html +//! [`BqlRefCell`]: ../../bql/cell/struct.BqlRefCell.html use std::{cell::UnsafeCell, fmt, marker::PhantomPinned, mem::MaybeUninit, ptr::NonNull}; /// Stores an opaque value that is shared with C code. diff --git a/rust/hw/char/pl011/Cargo.toml b/rust/hw/char/pl011/Cargo.toml index 7fd7531823..1a1d4ba715 100644 --- a/rust/hw/char/pl011/Cargo.toml +++ b/rust/hw/char/pl011/Cargo.toml @@ -18,6 +18,7 @@ bilge-impl = { version = "0.2.0" } bits = { path = "../../../bits" } common = { path = "../../../common" } util = { path = "../../../util" } +bql = { path = "../../../bql" } migration = { path = "../../../migration" } qemu_api = { path = "../../../qemu-api" } qemu_api_macros = { path = "../../../qemu-api-macros" } diff --git a/rust/hw/char/pl011/meson.build b/rust/hw/char/pl011/meson.build index 2198fcee9b..8561c4c14a 100644 --- a/rust/hw/char/pl011/meson.build +++ b/rust/hw/char/pl011/meson.build @@ -11,6 +11,7 @@ _libpl011_rs = static_library( qemu_api_rs, util_rs, migration_rs, + bql_rs, qemu_api_macros, ], ) diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs index 225be34e08..00ae432825 100644 --- a/rust/hw/char/pl011/src/device.rs +++ b/rust/hw/char/pl011/src/device.rs @@ -4,6 +4,7 @@ use std::{ffi::CStr, mem::size_of}; +use bql::BqlRefCell; use common::{static_assert, uninit_field_mut}; use migration::{ self, impl_vmstate_forward, impl_vmstate_struct, vmstate_fields, vmstate_of, diff --git a/rust/hw/timer/hpet/Cargo.toml b/rust/hw/timer/hpet/Cargo.toml index 70acdf03d6..9fcec38bfa 100644 --- a/rust/hw/timer/hpet/Cargo.toml +++ b/rust/hw/timer/hpet/Cargo.toml @@ -14,6 +14,7 @@ rust-version.workspace = true common = { path = "../../../common" } util = { path = "../../../util" } migration = { path = "../../../migration" } +bql = { path = "../../../bql" } qemu_api = { path = "../../../qemu-api" } qemu_api_macros = { path = "../../../qemu-api-macros" } diff --git a/rust/hw/timer/hpet/meson.build b/rust/hw/timer/hpet/meson.build index 8cd70091e6..43a62db0d0 100644 --- a/rust/hw/timer/hpet/meson.build +++ b/rust/hw/timer/hpet/meson.build @@ -8,6 +8,7 @@ _libhpet_rs = static_library( qemu_api_rs, util_rs, migration_rs, + bql_rs, qemu_api_macros, ], ) diff --git a/rust/hw/timer/hpet/src/device.rs b/rust/hw/timer/hpet/src/device.rs index 1c2253466d..9658e071c2 100644 --- a/rust/hw/timer/hpet/src/device.rs +++ b/rust/hw/timer/hpet/src/device.rs @@ -10,6 +10,7 @@ use std::{ slice::from_ref, }; +use bql::{BqlCell, BqlRefCell}; use common::{bitops::IntegerExt, uninit_field_mut}; use migration::{ self, impl_vmstate_struct, vmstate_fields, vmstate_of, vmstate_subsections, vmstate_validate, @@ -20,7 +21,6 @@ use qemu_api::{ address_space_memory, address_space_stl_le, qdev_prop_bit, qdev_prop_bool, qdev_prop_uint32, qdev_prop_usize, }, - cell::{BqlCell, BqlRefCell}, irq::InterruptSource, memory::{ hwaddr, MemoryRegion, MemoryRegionOps, MemoryRegionOpsBuilder, MEMTXATTRS_UNSPECIFIED, diff --git a/rust/hw/timer/hpet/src/fw_cfg.rs b/rust/hw/timer/hpet/src/fw_cfg.rs index 0605225fbb..e569b57b93 100644 --- a/rust/hw/timer/hpet/src/fw_cfg.rs +++ b/rust/hw/timer/hpet/src/fw_cfg.rs @@ -5,7 +5,6 @@ use std::ptr::addr_of_mut; use common::Zeroable; -use qemu_api::cell::bql_locked; /// Each `HPETState` represents a Event Timer Block. The v1 spec supports /// up to 8 blocks. QEMU only uses 1 block (in PC machine). @@ -38,7 +37,7 @@ pub static mut hpet_fw_cfg: HPETFwConfig = HPETFwConfig { impl HPETFwConfig { pub(crate) fn assign_hpet_id() -> Result { - assert!(bql_locked()); + assert!(bql::is_locked()); // SAFETY: all accesses go through these methods, which guarantee // that the accesses are protected by the BQL. let mut fw_cfg = unsafe { *addr_of_mut!(hpet_fw_cfg) }; @@ -58,7 +57,7 @@ impl HPETFwConfig { } pub(crate) fn update_hpet_cfg(hpet_id: usize, timer_block_id: u32, address: u64) { - assert!(bql_locked()); + assert!(bql::is_locked()); // SAFETY: all accesses go through these methods, which guarantee // that the accesses are protected by the BQL. let mut fw_cfg = unsafe { *addr_of_mut!(hpet_fw_cfg) }; diff --git a/rust/meson.build b/rust/meson.build index 826949b2e6..2ba1ea2280 100644 --- a/rust/meson.build +++ b/rust/meson.build @@ -27,6 +27,7 @@ subdir('qemu-api-macros') subdir('bits') subdir('util') subdir('migration') +subdir('bql') subdir('qemu-api') subdir('hw') diff --git a/rust/migration/src/vmstate.rs b/rust/migration/src/vmstate.rs index 537d54e436..d714aacb7e 100644 --- a/rust/migration/src/vmstate.rs +++ b/rust/migration/src/vmstate.rs @@ -135,8 +135,8 @@ pub const fn vmstate_varray_flag(_: PhantomData) -> VMStateFlags /// [`impl_vmstate_bitsized`](crate::impl_vmstate_bitsized), and /// [`impl_vmstate_struct`](crate::impl_vmstate_struct) help with this. /// -/// [`BqlCell`]: ../../qemu_api/cell/struct.BqlCell.html -/// [`BqlRefCell`]: ../../qemu_api/cell/struct.BqlRefCell.html +/// [`BqlCell`]: ../../bql/cell/struct.BqlCell.html +/// [`BqlRefCell`]: ../../bql/cell/struct.BqlRefCell.html /// [`Owned`]: ../../qemu_api/qom/struct.Owned.html #[macro_export] macro_rules! vmstate_of { diff --git a/rust/qemu-api/Cargo.toml b/rust/qemu-api/Cargo.toml index 7276e67aa9..6e9427f80c 100644 --- a/rust/qemu-api/Cargo.toml +++ b/rust/qemu-api/Cargo.toml @@ -17,11 +17,8 @@ rust-version.workspace = true common = { path = "../common" } migration = { path = "../migration" } util = { path = "../util" } +bql = { path = "../bql" } qemu_api_macros = { path = "../qemu-api-macros" } -[features] -default = ["debug_cell"] -debug_cell = [] - [lints] workspace = true diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index a6b5772d19..a47ee6c1a3 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -2,10 +2,6 @@ _qemu_api_cfg = run_command(rustc_args, '--config-headers', config_host_h, '--features', files('Cargo.toml'), capture: true, check: true).stdout().strip().splitlines() -if get_option('debug_mutex') - _qemu_api_cfg += ['--cfg', 'feature="debug_cell"'] -endif - c_enums = [ 'DeviceCategory', 'GpioPolarity', @@ -51,7 +47,6 @@ _qemu_api_rs = static_library( [ 'src/lib.rs', 'src/bindings.rs', - 'src/cell.rs', 'src/chardev.rs', 'src/irq.rs', 'src/memory.rs', @@ -65,22 +60,13 @@ _qemu_api_rs = static_library( override_options: ['rust_std=2021', 'build.rust_std=2021'], rust_abi: 'rust', rust_args: _qemu_api_cfg, - dependencies: [anyhow_rs, common_rs, foreign_rs, libc_rs, migration_rs, qemu_api_macros, + dependencies: [anyhow_rs, bql_rs, common_rs, foreign_rs, libc_rs, migration_rs, qemu_api_macros, util_rs, qom, hwcore, chardev], ) qemu_api_rs = declare_dependency(link_with: [_qemu_api_rs], dependencies: [qemu_api_macros, qom, hwcore, chardev, migration]) -# Doctests are essentially integration tests, so they need the same dependencies. -# Note that running them requires the object files for C code, so place them -# in a separate suite that is run by the "build" CI jobs rather than "check". -rust.doctest('rust-qemu-api-doctests', - _qemu_api_rs, - protocol: 'rust', - dependencies: [qemu_api_rs], - suite: ['doc', 'rust']) - test('rust-qemu-api-integration', executable( 'rust-qemu-api-integration', @@ -88,7 +74,7 @@ test('rust-qemu-api-integration', override_options: ['rust_std=2021', 'build.rust_std=2021'], rust_args: ['--test'], install: false, - dependencies: [common_rs, util_rs, migration_rs, qemu_api_rs]), + dependencies: [bql_rs, common_rs, util_rs, migration_rs, qemu_api_rs]), args: [ '--test', '--test-threads', '1', '--format', 'pretty', diff --git a/rust/qemu-api/src/cell.rs b/rust/qemu-api/src/cell.rs deleted file mode 100644 index b80a0fd80b..0000000000 --- a/rust/qemu-api/src/cell.rs +++ /dev/null @@ -1,874 +0,0 @@ -// SPDX-License-Identifier: MIT -// -// This file is based on library/core/src/cell.rs from -// Rust 1.82.0. -// -// Permission is hereby granted, free of charge, to any -// person obtaining a copy of this software and associated -// documentation files (the "Software"), to deal in the -// Software without restriction, including without -// limitation the rights to use, copy, modify, merge, -// publish, distribute, sublicense, and/or sell copies of -// the Software, and to permit persons to whom the Software -// is furnished to do so, subject to the following -// conditions: -// -// The above copyright notice and this permission notice -// shall be included in all copies or substantial portions -// of the Software. -// -// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF -// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED -// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A -// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT -// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY -// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION -// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR -// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER -// DEALINGS IN THE SOFTWARE. - -//! QEMU-specific mutable containers -//! -//! Rust memory safety is based on this rule: Given an object `T`, it is only -//! possible to have one of the following: -//! -//! - Having several immutable references (`&T`) to the object (also known as -//! **aliasing**). -//! - Having one mutable reference (`&mut T`) to the object (also known as -//! **mutability**). -//! -//! This is enforced by the Rust compiler. However, there are situations where -//! this rule is not flexible enough. Sometimes it is required to have multiple -//! references to an object and yet mutate it. In particular, QEMU objects -//! usually have their pointer shared with the "outside world very early in -//! their lifetime", for example when they create their -//! [`MemoryRegion`s](crate::bindings::MemoryRegion). Therefore, individual -//! parts of a device must be made mutable in a controlled manner; this module -//! provides the tools to do so. -//! -//! ## Cell types -//! -//! [`BqlCell`] and [`BqlRefCell`] allow doing this via the Big QEMU Lock. -//! While they are essentially the same single-threaded primitives that are -//! available in `std::cell`, the BQL allows them to be used from a -//! multi-threaded context and to share references across threads, while -//! maintaining Rust's safety guarantees. For this reason, unlike -//! their `std::cell` counterparts, `BqlCell` and `BqlRefCell` implement the -//! `Sync` trait. -//! -//! BQL checks are performed in debug builds but can be optimized away in -//! release builds, providing runtime safety during development with no overhead -//! in production. -//! -//! The two provide different ways of handling interior mutability. -//! `BqlRefCell` is best suited for data that is primarily accessed by the -//! device's own methods, where multiple reads and writes can be grouped within -//! a single borrow and a mutable reference can be passed around. Instead, -//! [`BqlCell`] is a better choice when sharing small pieces of data with -//! external code (especially C code), because it provides simple get/set -//! operations that can be used one at a time. -//! -//! Warning: While `BqlCell` and `BqlRefCell` are similar to their `std::cell` -//! counterparts, they are not interchangeable. Using `std::cell` types in -//! QEMU device implementations is usually incorrect and can lead to -//! thread-safety issues. -//! -//! ### Example -//! -//! ``` -//! # use qemu_api::prelude::*; -//! # use qemu_api::{cell::BqlRefCell, irq::InterruptSource, irq::IRQState}; -//! # use qemu_api::{sysbus::SysBusDevice, qom::Owned, qom::ParentField}; -//! # const N_GPIOS: usize = 8; -//! # struct PL061Registers { /* ... */ } -//! # unsafe impl ObjectType for PL061State { -//! # type Class = ::Class; -//! # const TYPE_NAME: &'static std::ffi::CStr = c"pl061"; -//! # } -//! struct PL061State { -//! parent_obj: ParentField, -//! -//! // Configuration is read-only after initialization -//! pullups: u32, -//! pulldowns: u32, -//! -//! // Single values shared with C code use BqlCell, in this case via InterruptSource -//! out: [InterruptSource; N_GPIOS], -//! interrupt: InterruptSource, -//! -//! // Larger state accessed by device methods uses BqlRefCell or Mutex -//! registers: BqlRefCell, -//! } -//! ``` -//! -//! ### `BqlCell` -//! -//! [`BqlCell`] implements interior mutability by moving values in and out of -//! the cell. That is, an `&mut T` to the inner value can never be obtained as -//! long as the cell is shared. The value itself cannot be directly obtained -//! without copying it, cloning it, or replacing it with something else. This -//! type provides the following methods, all of which can be called only while -//! the BQL is held: -//! -//! - For types that implement [`Copy`], the [`get`](BqlCell::get) method -//! retrieves the current interior value by duplicating it. -//! - For types that implement [`Default`], the [`take`](BqlCell::take) method -//! replaces the current interior value with [`Default::default()`] and -//! returns the replaced value. -//! - All types have: -//! - [`replace`](BqlCell::replace): replaces the current interior value and -//! returns the replaced value. -//! - [`set`](BqlCell::set): this method replaces the interior value, -//! dropping the replaced value. -//! -//! ### `BqlRefCell` -//! -//! [`BqlRefCell`] uses Rust's lifetimes to implement "dynamic borrowing", a -//! process whereby one can claim temporary, exclusive, mutable access to the -//! inner value: -//! -//! ```ignore -//! fn clear_interrupts(&self, val: u32) { -//! // A mutable borrow gives read-write access to the registers -//! let mut regs = self.registers.borrow_mut(); -//! let old = regs.interrupt_status(); -//! regs.update_interrupt_status(old & !val); -//! } -//! ``` -//! -//! Borrows for `BqlRefCell`s are tracked at _runtime_, unlike Rust's native -//! reference types which are entirely tracked statically, at compile time. -//! Multiple immutable borrows are allowed via [`borrow`](BqlRefCell::borrow), -//! or a single mutable borrow via [`borrow_mut`](BqlRefCell::borrow_mut). The -//! thread will panic if these rules are violated or if the BQL is not held. - -use std::{ - cell::{Cell, UnsafeCell}, - cmp::Ordering, - fmt, - marker::PhantomData, - mem, - ops::{Deref, DerefMut}, - ptr::NonNull, -}; - -use migration::impl_vmstate_transparent; - -use crate::bindings; - -/// An internal function that is used by doctests. -pub fn bql_start_test() { - // SAFETY: integration tests are run with --test-threads=1, while - // unit tests and doctests are not multithreaded and do not have - // any BQL-protected data. Just set bql_locked to true. - unsafe { - bindings::rust_bql_mock_lock(); - } -} - -pub fn bql_locked() -> bool { - // SAFETY: the function does nothing but return a thread-local bool - unsafe { bindings::bql_locked() } -} - -fn bql_block_unlock(increase: bool) { - // SAFETY: this only adjusts a counter - unsafe { - bindings::bql_block_unlock(increase); - } -} - -/// A mutable memory location that is protected by the Big QEMU Lock. -/// -/// # Memory layout -/// -/// `BqlCell` has the same in-memory representation as its inner type `T`. -#[repr(transparent)] -pub struct BqlCell { - value: UnsafeCell, -} - -// SAFETY: Same as for std::sync::Mutex. In the end this *is* a Mutex, -// except it is stored out-of-line -unsafe impl Send for BqlCell {} -unsafe impl Sync for BqlCell {} - -impl Clone for BqlCell { - #[inline] - fn clone(&self) -> BqlCell { - BqlCell::new(self.get()) - } -} - -impl Default for BqlCell { - /// Creates a `BqlCell`, with the `Default` value for T. - #[inline] - fn default() -> BqlCell { - BqlCell::new(Default::default()) - } -} - -impl PartialEq for BqlCell { - #[inline] - fn eq(&self, other: &BqlCell) -> bool { - self.get() == other.get() - } -} - -impl Eq for BqlCell {} - -impl PartialOrd for BqlCell { - #[inline] - fn partial_cmp(&self, other: &BqlCell) -> Option { - self.get().partial_cmp(&other.get()) - } -} - -impl Ord for BqlCell { - #[inline] - fn cmp(&self, other: &BqlCell) -> Ordering { - self.get().cmp(&other.get()) - } -} - -impl From for BqlCell { - /// Creates a new `BqlCell` containing the given value. - fn from(t: T) -> BqlCell { - BqlCell::new(t) - } -} - -impl fmt::Debug for BqlCell { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - self.get().fmt(f) - } -} - -impl fmt::Display for BqlCell { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - self.get().fmt(f) - } -} - -impl BqlCell { - /// Creates a new `BqlCell` containing the given value. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let c = BqlCell::new(5); - /// ``` - #[inline] - pub const fn new(value: T) -> BqlCell { - BqlCell { - value: UnsafeCell::new(value), - } - } - - /// Sets the contained value. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let c = BqlCell::new(5); - /// - /// c.set(10); - /// ``` - #[inline] - pub fn set(&self, val: T) { - self.replace(val); - } - - /// Replaces the contained value with `val`, and returns the old contained - /// value. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let cell = BqlCell::new(5); - /// assert_eq!(cell.get(), 5); - /// assert_eq!(cell.replace(10), 5); - /// assert_eq!(cell.get(), 10); - /// ``` - #[inline] - pub fn replace(&self, val: T) -> T { - assert!(bql_locked()); - // SAFETY: This can cause data races if called from multiple threads, - // but it won't happen as long as C code accesses the value - // under BQL protection only. - mem::replace(unsafe { &mut *self.value.get() }, val) - } - - /// Unwraps the value, consuming the cell. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let c = BqlCell::new(5); - /// let five = c.into_inner(); - /// - /// assert_eq!(five, 5); - /// ``` - pub fn into_inner(self) -> T { - assert!(bql_locked()); - self.value.into_inner() - } -} - -impl BqlCell { - /// Returns a copy of the contained value. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let c = BqlCell::new(5); - /// - /// let five = c.get(); - /// ``` - #[inline] - pub fn get(&self) -> T { - assert!(bql_locked()); - // SAFETY: This can cause data races if called from multiple threads, - // but it won't happen as long as C code accesses the value - // under BQL protection only. - unsafe { *self.value.get() } - } -} - -impl BqlCell { - /// Returns a raw pointer to the underlying data in this cell. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let c = BqlCell::new(5); - /// - /// let ptr = c.as_ptr(); - /// ``` - #[inline] - pub const fn as_ptr(&self) -> *mut T { - self.value.get() - } -} - -impl BqlCell { - /// Takes the value of the cell, leaving `Default::default()` in its place. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let c = BqlCell::new(5); - /// let five = c.take(); - /// - /// assert_eq!(five, 5); - /// assert_eq!(c.into_inner(), 0); - /// ``` - pub fn take(&self) -> T { - self.replace(Default::default()) - } -} - -impl_vmstate_transparent!(crate::cell::BqlCell where T: VMState); - -/// A mutable memory location with dynamically checked borrow rules, -/// protected by the Big QEMU Lock. -/// -/// See the [module-level documentation](self) for more. -/// -/// # Memory layout -/// -/// `BqlRefCell` starts with the same in-memory representation as its -/// inner type `T`. -#[repr(C)] -pub struct BqlRefCell { - // It is important that this is the first field (which is not the case - // for std::cell::BqlRefCell), so that we can use offset_of! on it. - // UnsafeCell and repr(C) both prevent usage of niches. - value: UnsafeCell, - borrow: Cell, - // Stores the location of the earliest currently active borrow. - // This gets updated whenever we go from having zero borrows - // to having a single borrow. When a borrow occurs, this gets included - // in the panic message - #[cfg(feature = "debug_cell")] - borrowed_at: Cell>>, -} - -// Positive values represent the number of `BqlRef` active. Negative values -// represent the number of `BqlRefMut` active. Right now QEMU's implementation -// does not allow to create `BqlRefMut`s that refer to distinct, nonoverlapping -// components of a `BqlRefCell` (e.g., different ranges of a slice). -// -// `BqlRef` and `BqlRefMut` are both two words in size, and so there will likely -// never be enough `BqlRef`s or `BqlRefMut`s in existence to overflow half of -// the `usize` range. Thus, a `BorrowFlag` will probably never overflow or -// underflow. However, this is not a guarantee, as a pathological program could -// repeatedly create and then mem::forget `BqlRef`s or `BqlRefMut`s. Thus, all -// code must explicitly check for overflow and underflow in order to avoid -// unsafety, or at least behave correctly in the event that overflow or -// underflow happens (e.g., see BorrowRef::new). -type BorrowFlag = isize; -const UNUSED: BorrowFlag = 0; - -#[inline(always)] -const fn is_writing(x: BorrowFlag) -> bool { - x < UNUSED -} - -#[inline(always)] -const fn is_reading(x: BorrowFlag) -> bool { - x > UNUSED -} - -impl BqlRefCell { - /// Creates a new `BqlRefCell` containing `value`. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlRefCell; - /// - /// let c = BqlRefCell::new(5); - /// ``` - #[inline] - pub const fn new(value: T) -> BqlRefCell { - BqlRefCell { - value: UnsafeCell::new(value), - borrow: Cell::new(UNUSED), - #[cfg(feature = "debug_cell")] - borrowed_at: Cell::new(None), - } - } -} - -// This ensures the panicking code is outlined from `borrow_mut` for -// `BqlRefCell`. -#[inline(never)] -#[cold] -#[cfg(feature = "debug_cell")] -fn panic_already_borrowed(source: &Cell>>) -> ! { - // If a borrow occurred, then we must already have an outstanding borrow, - // so `borrowed_at` will be `Some` - panic!("already borrowed at {:?}", source.take().unwrap()) -} - -#[inline(never)] -#[cold] -#[cfg(not(feature = "debug_cell"))] -fn panic_already_borrowed() -> ! { - panic!("already borrowed") -} - -impl BqlRefCell { - #[inline] - #[allow(clippy::unused_self)] - fn panic_already_borrowed(&self) -> ! { - #[cfg(feature = "debug_cell")] - { - panic_already_borrowed(&self.borrowed_at) - } - #[cfg(not(feature = "debug_cell"))] - { - panic_already_borrowed() - } - } - - /// Immutably borrows the wrapped value. - /// - /// The borrow lasts until the returned `BqlRef` exits scope. Multiple - /// immutable borrows can be taken out at the same time. - /// - /// # Panics - /// - /// Panics if the value is currently mutably borrowed. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlRefCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let c = BqlRefCell::new(5); - /// - /// let borrowed_five = c.borrow(); - /// let borrowed_five2 = c.borrow(); - /// ``` - /// - /// An example of panic: - /// - /// ```should_panic - /// use qemu_api::cell::BqlRefCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let c = BqlRefCell::new(5); - /// - /// let m = c.borrow_mut(); - /// let b = c.borrow(); // this causes a panic - /// ``` - #[inline] - #[track_caller] - pub fn borrow(&self) -> BqlRef<'_, T> { - if let Some(b) = BorrowRef::new(&self.borrow) { - // `borrowed_at` is always the *first* active borrow - if b.borrow.get() == 1 { - #[cfg(feature = "debug_cell")] - self.borrowed_at.set(Some(std::panic::Location::caller())); - } - - bql_block_unlock(true); - - // SAFETY: `BorrowRef` ensures that there is only immutable access - // to the value while borrowed. - let value = unsafe { NonNull::new_unchecked(self.value.get()) }; - BqlRef { value, borrow: b } - } else { - self.panic_already_borrowed() - } - } - - /// Mutably borrows the wrapped value. - /// - /// The borrow lasts until the returned `BqlRefMut` or all `BqlRefMut`s - /// derived from it exit scope. The value cannot be borrowed while this - /// borrow is active. - /// - /// # Panics - /// - /// Panics if the value is currently borrowed. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlRefCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let c = BqlRefCell::new("hello".to_owned()); - /// - /// *c.borrow_mut() = "bonjour".to_owned(); - /// - /// assert_eq!(&*c.borrow(), "bonjour"); - /// ``` - /// - /// An example of panic: - /// - /// ```should_panic - /// use qemu_api::cell::BqlRefCell; - /// # qemu_api::cell::bql_start_test(); - /// - /// let c = BqlRefCell::new(5); - /// let m = c.borrow(); - /// - /// let b = c.borrow_mut(); // this causes a panic - /// ``` - #[inline] - #[track_caller] - pub fn borrow_mut(&self) -> BqlRefMut<'_, T> { - if let Some(b) = BorrowRefMut::new(&self.borrow) { - #[cfg(feature = "debug_cell")] - { - self.borrowed_at.set(Some(std::panic::Location::caller())); - } - - // SAFETY: this only adjusts a counter - bql_block_unlock(true); - - // SAFETY: `BorrowRefMut` guarantees unique access. - let value = unsafe { NonNull::new_unchecked(self.value.get()) }; - BqlRefMut { - value, - _borrow: b, - marker: PhantomData, - } - } else { - self.panic_already_borrowed() - } - } - - /// Returns a raw pointer to the underlying data in this cell. - /// - /// # Examples - /// - /// ``` - /// use qemu_api::cell::BqlRefCell; - /// - /// let c = BqlRefCell::new(5); - /// - /// let ptr = c.as_ptr(); - /// ``` - #[inline] - pub const fn as_ptr(&self) -> *mut T { - self.value.get() - } -} - -// SAFETY: Same as for std::sync::Mutex. In the end this is a Mutex that is -// stored out-of-line. Even though BqlRefCell includes Cells, they are -// themselves protected by the Big QEMU Lock. Furtheremore, the Big QEMU -// Lock cannot be released while any borrows is active. -unsafe impl Send for BqlRefCell where T: Send {} -unsafe impl Sync for BqlRefCell {} - -impl Clone for BqlRefCell { - /// # Panics - /// - /// Panics if the value is currently mutably borrowed. - #[inline] - #[track_caller] - fn clone(&self) -> BqlRefCell { - BqlRefCell::new(self.borrow().clone()) - } - - /// # Panics - /// - /// Panics if `source` is currently mutably borrowed. - #[inline] - #[track_caller] - fn clone_from(&mut self, source: &Self) { - self.value.get_mut().clone_from(&source.borrow()) - } -} - -impl Default for BqlRefCell { - /// Creates a `BqlRefCell`, with the `Default` value for T. - #[inline] - fn default() -> BqlRefCell { - BqlRefCell::new(Default::default()) - } -} - -impl PartialEq for BqlRefCell { - /// # Panics - /// - /// Panics if the value in either `BqlRefCell` is currently mutably - /// borrowed. - #[inline] - fn eq(&self, other: &BqlRefCell) -> bool { - *self.borrow() == *other.borrow() - } -} - -impl Eq for BqlRefCell {} - -impl PartialOrd for BqlRefCell { - /// # Panics - /// - /// Panics if the value in either `BqlRefCell` is currently mutably - /// borrowed. - #[inline] - fn partial_cmp(&self, other: &BqlRefCell) -> Option { - self.borrow().partial_cmp(&*other.borrow()) - } -} - -impl Ord for BqlRefCell { - /// # Panics - /// - /// Panics if the value in either `BqlRefCell` is currently mutably - /// borrowed. - #[inline] - fn cmp(&self, other: &BqlRefCell) -> Ordering { - self.borrow().cmp(&*other.borrow()) - } -} - -impl From for BqlRefCell { - /// Creates a new `BqlRefCell` containing the given value. - fn from(t: T) -> BqlRefCell { - BqlRefCell::new(t) - } -} - -impl_vmstate_transparent!(crate::cell::BqlRefCell where T: VMState); - -struct BorrowRef<'b> { - borrow: &'b Cell, -} - -impl<'b> BorrowRef<'b> { - #[inline] - fn new(borrow: &'b Cell) -> Option> { - let b = borrow.get().wrapping_add(1); - if !is_reading(b) { - // Incrementing borrow can result in a non-reading value (<= 0) in these cases: - // 1. It was < 0, i.e. there are writing borrows, so we can't allow a read - // borrow due to Rust's reference aliasing rules - // 2. It was isize::MAX (the max amount of reading borrows) and it overflowed - // into isize::MIN (the max amount of writing borrows) so we can't allow an - // additional read borrow because isize can't represent so many read borrows - // (this can only happen if you mem::forget more than a small constant amount - // of `BqlRef`s, which is not good practice) - None - } else { - // Incrementing borrow can result in a reading value (> 0) in these cases: - // 1. It was = 0, i.e. it wasn't borrowed, and we are taking the first read - // borrow - // 2. It was > 0 and < isize::MAX, i.e. there were read borrows, and isize is - // large enough to represent having one more read borrow - borrow.set(b); - Some(BorrowRef { borrow }) - } - } -} - -impl Drop for BorrowRef<'_> { - #[inline] - fn drop(&mut self) { - let borrow = self.borrow.get(); - debug_assert!(is_reading(borrow)); - self.borrow.set(borrow - 1); - bql_block_unlock(false) - } -} - -impl Clone for BorrowRef<'_> { - #[inline] - fn clone(&self) -> Self { - BorrowRef::new(self.borrow).unwrap() - } -} - -/// Wraps a borrowed reference to a value in a `BqlRefCell` box. -/// A wrapper type for an immutably borrowed value from a `BqlRefCell`. -/// -/// See the [module-level documentation](self) for more. -pub struct BqlRef<'b, T: 'b> { - // NB: we use a pointer instead of `&'b T` to avoid `noalias` violations, because a - // `BqlRef` argument doesn't hold immutability for its whole scope, only until it drops. - // `NonNull` is also covariant over `T`, just like we would have with `&T`. - value: NonNull, - borrow: BorrowRef<'b>, -} - -impl Deref for BqlRef<'_, T> { - type Target = T; - - #[inline] - fn deref(&self) -> &T { - // SAFETY: the value is accessible as long as we hold our borrow. - unsafe { self.value.as_ref() } - } -} - -impl<'b, T> BqlRef<'b, T> { - /// Copies a `BqlRef`. - /// - /// The `BqlRefCell` is already immutably borrowed, so this cannot fail. - /// - /// This is an associated function that needs to be used as - /// `BqlRef::clone(...)`. A `Clone` implementation or a method would - /// interfere with the widespread use of `r.borrow().clone()` to clone - /// the contents of a `BqlRefCell`. - #[must_use] - #[inline] - #[allow(clippy::should_implement_trait)] - pub fn clone(orig: &BqlRef<'b, T>) -> BqlRef<'b, T> { - BqlRef { - value: orig.value, - borrow: orig.borrow.clone(), - } - } -} - -impl fmt::Debug for BqlRef<'_, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -impl fmt::Display for BqlRef<'_, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -struct BorrowRefMut<'b> { - borrow: &'b Cell, -} - -impl<'b> BorrowRefMut<'b> { - #[inline] - fn new(borrow: &'b Cell) -> Option> { - // There must currently be no existing references when borrow_mut() is - // called, so we explicitly only allow going from UNUSED to UNUSED - 1. - match borrow.get() { - UNUSED => { - borrow.set(UNUSED - 1); - Some(BorrowRefMut { borrow }) - } - _ => None, - } - } -} - -impl Drop for BorrowRefMut<'_> { - #[inline] - fn drop(&mut self) { - let borrow = self.borrow.get(); - debug_assert!(is_writing(borrow)); - self.borrow.set(borrow + 1); - bql_block_unlock(false) - } -} - -/// A wrapper type for a mutably borrowed value from a `BqlRefCell`. -/// -/// See the [module-level documentation](self) for more. -pub struct BqlRefMut<'b, T: 'b> { - // NB: we use a pointer instead of `&'b mut T` to avoid `noalias` violations, because a - // `BqlRefMut` argument doesn't hold exclusivity for its whole scope, only until it drops. - value: NonNull, - _borrow: BorrowRefMut<'b>, - // `NonNull` is covariant over `T`, so we need to reintroduce invariance. - marker: PhantomData<&'b mut T>, -} - -impl Deref for BqlRefMut<'_, T> { - type Target = T; - - #[inline] - fn deref(&self) -> &T { - // SAFETY: the value is accessible as long as we hold our borrow. - unsafe { self.value.as_ref() } - } -} - -impl DerefMut for BqlRefMut<'_, T> { - #[inline] - fn deref_mut(&mut self) -> &mut T { - // SAFETY: the value is accessible as long as we hold our borrow. - unsafe { self.value.as_mut() } - } -} - -impl fmt::Debug for BqlRefMut<'_, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -impl fmt::Display for BqlRefMut<'_, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} diff --git a/rust/qemu-api/src/chardev.rs b/rust/qemu-api/src/chardev.rs index 5a351dcecb..2ec90cc0b2 100644 --- a/rust/qemu-api/src/chardev.rs +++ b/rust/qemu-api/src/chardev.rs @@ -18,13 +18,10 @@ use std::{ slice, }; +use bql::{BqlRefCell, BqlRefMut}; use common::{callbacks::FnCall, errno, Opaque}; -use crate::{ - bindings, - cell::{BqlRefCell, BqlRefMut}, - prelude::*, -}; +use crate::{bindings, prelude::*}; /// A safe wrapper around [`bindings::Chardev`]. #[repr(transparent)] @@ -44,13 +41,15 @@ pub struct CharBackend { _pin: PhantomPinned, } -impl Write for BqlRefMut<'_, bindings::CharBackend> { +pub struct CharBackendMut<'a>(BqlRefMut<'a, bindings::CharBackend>); + +impl Write for CharBackendMut<'_> { fn flush(&mut self) -> io::Result<()> { Ok(()) } fn write(&mut self, buf: &[u8]) -> io::Result { - let chr: &mut bindings::CharBackend = self; + let chr: &mut bindings::CharBackend = &mut self.0; let len = buf.len().try_into().unwrap(); let r = unsafe { bindings::qemu_chr_fe_write(addr_of_mut!(*chr), buf.as_ptr(), len) }; @@ -58,7 +57,7 @@ impl Write for BqlRefMut<'_, bindings::CharBackend> { } fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { - let chr: &mut bindings::CharBackend = self; + let chr: &mut bindings::CharBackend = &mut self.0; let len = buf.len().try_into().unwrap(); let r = unsafe { bindings::qemu_chr_fe_write_all(addr_of_mut!(*chr), buf.as_ptr(), len) }; @@ -198,7 +197,7 @@ impl CharBackend { /// the big QEMU lock while the character device is borrowed, as /// that might cause C code to write to the character device. pub fn borrow_mut(&self) -> impl Write + '_ { - self.inner.borrow_mut() + CharBackendMut(self.inner.borrow_mut()) } /// Send a continuous stream of zero bits on the line if `enabled` is diff --git a/rust/qemu-api/src/irq.rs b/rust/qemu-api/src/irq.rs index ea6b32848c..3063fbe97a 100644 --- a/rust/qemu-api/src/irq.rs +++ b/rust/qemu-api/src/irq.rs @@ -10,6 +10,7 @@ use std::{ ptr, }; +use bql::BqlCell; use common::Opaque; use crate::{ diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs index 55386f6697..6cd9e5b990 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -13,7 +13,6 @@ pub mod bindings; #[rustfmt::skip] pub mod prelude; -pub mod cell; pub mod chardev; pub mod irq; pub mod memory; diff --git a/rust/qemu-api/src/prelude.rs b/rust/qemu-api/src/prelude.rs index c10c171158..9da7313016 100644 --- a/rust/qemu-api/src/prelude.rs +++ b/rust/qemu-api/src/prelude.rs @@ -4,9 +4,6 @@ //! Commonly used traits and types for QEMU. -pub use crate::cell::BqlCell; -pub use crate::cell::BqlRefCell; - pub use crate::qdev::DeviceMethods; pub use crate::qom::InterfaceType; diff --git a/rust/qemu-api/src/qdev.rs b/rust/qemu-api/src/qdev.rs index c81ae7cf45..74a82b8710 100644 --- a/rust/qemu-api/src/qdev.rs +++ b/rust/qemu-api/src/qdev.rs @@ -16,7 +16,6 @@ use util::{Error, Result}; use crate::{ bindings::{self, qdev_init_gpio_in, qdev_init_gpio_out, ResettableClass}, - cell::bql_locked, chardev::Chardev, irq::InterruptSource, prelude::*, @@ -322,7 +321,7 @@ impl DeviceState { cb: Option, events: ClockEvent, ) -> Owned { - assert!(bql_locked()); + assert!(bql::is_locked()); // SAFETY: the clock is heap allocated, but qdev_init_clock_in() // does not gift the reference to its caller; so use Owned::from to @@ -393,7 +392,7 @@ where Self::Target: IsA, { fn prop_set_chr(&self, propname: &str, chr: &Owned) { - assert!(bql_locked()); + assert!(bql::is_locked()); let c_propname = CString::new(propname).unwrap(); let chr: &Chardev = chr; unsafe { diff --git a/rust/qemu-api/src/qom.rs b/rust/qemu-api/src/qom.rs index 7f2f7797e4..032701af65 100644 --- a/rust/qemu-api/src/qom.rs +++ b/rust/qemu-api/src/qom.rs @@ -105,12 +105,9 @@ pub use bindings::ObjectClass; use common::Opaque; use migration::impl_vmstate_pointer; -use crate::{ - bindings::{ - self, object_class_dynamic_cast, object_dynamic_cast, object_get_class, - object_get_typename, object_new, object_ref, object_unref, TypeInfo, - }, - cell::bql_locked, +use crate::bindings::{ + self, object_class_dynamic_cast, object_dynamic_cast, object_get_class, object_get_typename, + object_new, object_ref, object_unref, TypeInfo, }; /// A safe wrapper around [`bindings::Object`]. @@ -873,7 +870,7 @@ impl ObjectDeref for Owned {} impl Drop for Owned { fn drop(&mut self) { - assert!(bql_locked()); + assert!(bql::is_locked()); // SAFETY: creation method is unsafe, and whoever calls it has // responsibility that the pointer is valid, and remains valid // throughout the lifetime of the `Owned` and its clones. @@ -897,7 +894,7 @@ impl> fmt::Debug for Owned { pub trait ObjectClassMethods: IsA { /// Return a new reference counted instance of this class fn new() -> Owned { - assert!(bql_locked()); + assert!(bql::is_locked()); // SAFETY: the object created by object_new is allocated on // the heap and has a reference count of 1 unsafe { diff --git a/rust/qemu-api/src/sysbus.rs b/rust/qemu-api/src/sysbus.rs index 2dbfc31dbd..b21883246e 100644 --- a/rust/qemu-api/src/sysbus.rs +++ b/rust/qemu-api/src/sysbus.rs @@ -11,7 +11,6 @@ use common::Opaque; use crate::{ bindings, - cell::bql_locked, irq::{IRQState, InterruptSource}, memory::MemoryRegion, prelude::*, @@ -56,7 +55,7 @@ where /// region with a number that corresponds to the order of calls to /// `init_mmio`. fn init_mmio(&self, iomem: &MemoryRegion) { - assert!(bql_locked()); + assert!(bql::is_locked()); unsafe { bindings::sysbus_init_mmio(self.upcast().as_mut_ptr(), iomem.as_mut_ptr()); } @@ -67,7 +66,7 @@ where /// whoever creates the sysbus device will refer to the interrupts with /// a number that corresponds to the order of calls to `init_irq`. fn init_irq(&self, irq: &InterruptSource) { - assert!(bql_locked()); + assert!(bql::is_locked()); unsafe { bindings::sysbus_init_irq(self.upcast().as_mut_ptr(), irq.as_ptr()); } @@ -75,7 +74,7 @@ where // TODO: do we want a type like GuestAddress here? fn mmio_addr(&self, id: u32) -> Option { - assert!(bql_locked()); + assert!(bql::is_locked()); // SAFETY: the BQL ensures that no one else writes to sbd.mmio[], and // the SysBusDevice must be initialized to get an IsA. let sbd = unsafe { *self.upcast().as_ptr() }; @@ -89,7 +88,7 @@ where // TODO: do we want a type like GuestAddress here? fn mmio_map(&self, id: u32, addr: u64) { - assert!(bql_locked()); + assert!(bql::is_locked()); let id: i32 = id.try_into().unwrap(); unsafe { bindings::sysbus_mmio_map(self.upcast().as_mut_ptr(), id, addr); @@ -100,7 +99,7 @@ where // object_property_set_link) adds a reference to the IRQState, // which can prolong its life fn connect_irq(&self, id: u32, irq: &Owned) { - assert!(bql_locked()); + assert!(bql::is_locked()); let id: i32 = id.try_into().unwrap(); let irq: &IRQState = irq; unsafe { @@ -110,7 +109,7 @@ where fn sysbus_realize(&self) { // TODO: return an Error - assert!(bql_locked()); + assert!(bql::is_locked()); unsafe { bindings::sysbus_realize( self.upcast().as_mut_ptr(), diff --git a/rust/qemu-api/tests/tests.rs b/rust/qemu-api/tests/tests.rs index 92e3534d3c..e72ba08aef 100644 --- a/rust/qemu-api/tests/tests.rs +++ b/rust/qemu-api/tests/tests.rs @@ -4,9 +4,9 @@ use std::{ffi::CStr, ptr::addr_of}; +use bql::BqlCell; use migration::{VMStateDescription, VMStateDescriptionBuilder}; use qemu_api::{ - cell::{self, BqlCell}, prelude::*, qdev::{DeviceImpl, DeviceState, ResettablePhasesImpl}, qom::{ObjectImpl, ParentField}, @@ -94,7 +94,7 @@ impl DummyChildClass { fn init_qom() { static ONCE: BqlCell = BqlCell::new(false); - cell::bql_start_test(); + bql::start_test(); if !ONCE.get() { unsafe { module_call_init(module_init_type::MODULE_INIT_QOM); diff --git a/rust/qemu-api/tests/vmstate_tests.rs b/rust/qemu-api/tests/vmstate_tests.rs index 47fc15149b..fa9bbd6a12 100644 --- a/rust/qemu-api/tests/vmstate_tests.rs +++ b/rust/qemu-api/tests/vmstate_tests.rs @@ -9,6 +9,7 @@ use std::{ slice, }; +use bql::BqlCell; use common::Opaque; use migration::{ bindings::{ @@ -19,7 +20,6 @@ use migration::{ vmstate::{VMStateDescription, VMStateDescriptionBuilder, VMStateField}, vmstate_fields, vmstate_of, vmstate_unused, vmstate_validate, }; -use qemu_api::cell::BqlCell; const FOO_ARRAY_MAX: usize = 3; -- cgit 1.4.1 From fcf4c00b4d73185db9239b1a6f03289f6211e142 Mon Sep 17 00:00:00 2001 From: Marc-André Lureau Date: Mon, 8 Sep 2025 12:49:53 +0200 Subject: rust: split "qom" crate MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Marc-André Lureau Reviewed-by: Zhao Liu Link: https://lore.kernel.org/r/20250827104147.717203-13-marcandre.lureau@redhat.com Signed-off-by: Paolo Bonzini --- MAINTAINERS | 1 + rust/Cargo.lock | 14 + rust/Cargo.toml | 1 + rust/hw/char/pl011/Cargo.toml | 1 + rust/hw/char/pl011/meson.build | 1 + rust/hw/char/pl011/src/device.rs | 2 +- rust/hw/timer/hpet/Cargo.toml | 1 + rust/hw/timer/hpet/meson.build | 1 + rust/hw/timer/hpet/src/device.rs | 3 +- rust/meson.build | 1 + rust/migration/src/vmstate.rs | 2 +- rust/qemu-api-macros/src/lib.rs | 4 +- rust/qemu-api-macros/src/tests.rs | 4 +- rust/qemu-api/Cargo.toml | 1 + rust/qemu-api/meson.build | 15 +- rust/qemu-api/src/bindings.rs | 1 + rust/qemu-api/src/chardev.rs | 3 +- rust/qemu-api/src/irq.rs | 10 +- rust/qemu-api/src/lib.rs | 1 - rust/qemu-api/src/memory.rs | 7 +- rust/qemu-api/src/prelude.rs | 11 - rust/qemu-api/src/qdev.rs | 5 +- rust/qemu-api/src/qom.rs | 951 -------------------------------------- rust/qemu-api/src/sysbus.rs | 4 +- rust/qemu-api/tests/tests.rs | 3 +- rust/qom/Cargo.toml | 23 + rust/qom/build.rs | 1 + rust/qom/meson.build | 43 ++ rust/qom/src/bindings.rs | 25 + rust/qom/src/lib.rs | 11 + rust/qom/src/prelude.rs | 12 + rust/qom/src/qom.rs | 951 ++++++++++++++++++++++++++++++++++++++ rust/qom/wrapper.h | 27 ++ 33 files changed, 1148 insertions(+), 993 deletions(-) delete mode 100644 rust/qemu-api/src/qom.rs create mode 100644 rust/qom/Cargo.toml create mode 120000 rust/qom/build.rs create mode 100644 rust/qom/meson.build create mode 100644 rust/qom/src/bindings.rs create mode 100644 rust/qom/src/lib.rs create mode 100644 rust/qom/src/prelude.rs create mode 100644 rust/qom/src/qom.rs create mode 100644 rust/qom/wrapper.h (limited to 'rust/qemu-api/src/chardev.rs') diff --git a/MAINTAINERS b/MAINTAINERS index a55d5c95d7..c7bd02aef1 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3520,6 +3520,7 @@ F: rust/common/ F: rust/migration/ F: rust/qemu-api F: rust/qemu-api-macros +F: rust/qom/ F: rust/rustfmt.toml F: rust/util/ F: scripts/get-wraps-from-cargo-registry.py diff --git a/rust/Cargo.lock b/rust/Cargo.lock index 73ca9582a5..442eadf08f 100644 --- a/rust/Cargo.lock +++ b/rust/Cargo.lock @@ -82,6 +82,7 @@ dependencies = [ "migration", "qemu_api", "qemu_api_macros", + "qom", "util", ] @@ -121,6 +122,7 @@ dependencies = [ "migration", "qemu_api", "qemu_api_macros", + "qom", "util", ] @@ -164,6 +166,7 @@ dependencies = [ "common", "migration", "qemu_api_macros", + "qom", "util", ] @@ -176,6 +179,17 @@ dependencies = [ "syn", ] +[[package]] +name = "qom" +version = "0.1.0" +dependencies = [ + "bql", + "common", + "migration", + "qemu_api_macros", + "util", +] + [[package]] name = "quote" version = "1.0.36" diff --git a/rust/Cargo.toml b/rust/Cargo.toml index 8be90da8ff..0516c16591 100644 --- a/rust/Cargo.toml +++ b/rust/Cargo.toml @@ -7,6 +7,7 @@ members = [ "migration", "qemu-api-macros", "qemu-api", + "qom", "hw/char/pl011", "hw/timer/hpet", "util", diff --git a/rust/hw/char/pl011/Cargo.toml b/rust/hw/char/pl011/Cargo.toml index 1a1d4ba715..da89f78727 100644 --- a/rust/hw/char/pl011/Cargo.toml +++ b/rust/hw/char/pl011/Cargo.toml @@ -20,6 +20,7 @@ common = { path = "../../../common" } util = { path = "../../../util" } bql = { path = "../../../bql" } migration = { path = "../../../migration" } +qom = { path = "../../../qom" } qemu_api = { path = "../../../qemu-api" } qemu_api_macros = { path = "../../../qemu-api-macros" } diff --git a/rust/hw/char/pl011/meson.build b/rust/hw/char/pl011/meson.build index 8561c4c14a..af9393c9da 100644 --- a/rust/hw/char/pl011/meson.build +++ b/rust/hw/char/pl011/meson.build @@ -13,6 +13,7 @@ _libpl011_rs = static_library( migration_rs, bql_rs, qemu_api_macros, + qom_rs, ], ) diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs index 00ae432825..63651b9dcd 100644 --- a/rust/hw/char/pl011/src/device.rs +++ b/rust/hw/char/pl011/src/device.rs @@ -16,9 +16,9 @@ use qemu_api::{ memory::{hwaddr, MemoryRegion, MemoryRegionOps, MemoryRegionOpsBuilder}, prelude::*, qdev::{Clock, ClockEvent, DeviceImpl, DeviceState, ResetType, ResettablePhasesImpl}, - qom::{ObjectImpl, Owned, ParentField, ParentInit}, sysbus::{SysBusDevice, SysBusDeviceImpl}, }; +use qom::{prelude::*, ObjectImpl, Owned, ParentField, ParentInit}; use util::{log::Log, log_mask_ln}; use crate::registers::{self, Interrupt, RegisterOffset}; diff --git a/rust/hw/timer/hpet/Cargo.toml b/rust/hw/timer/hpet/Cargo.toml index 9fcec38bfa..19456ec72b 100644 --- a/rust/hw/timer/hpet/Cargo.toml +++ b/rust/hw/timer/hpet/Cargo.toml @@ -15,6 +15,7 @@ common = { path = "../../../common" } util = { path = "../../../util" } migration = { path = "../../../migration" } bql = { path = "../../../bql" } +qom = { path = "../../../qom" } qemu_api = { path = "../../../qemu-api" } qemu_api_macros = { path = "../../../qemu-api-macros" } diff --git a/rust/hw/timer/hpet/meson.build b/rust/hw/timer/hpet/meson.build index 43a62db0d0..50ccdee4a9 100644 --- a/rust/hw/timer/hpet/meson.build +++ b/rust/hw/timer/hpet/meson.build @@ -10,6 +10,7 @@ _libhpet_rs = static_library( migration_rs, bql_rs, qemu_api_macros, + qom_rs, ], ) diff --git a/rust/hw/timer/hpet/src/device.rs b/rust/hw/timer/hpet/src/device.rs index 9658e071c2..404569aa2d 100644 --- a/rust/hw/timer/hpet/src/device.rs +++ b/rust/hw/timer/hpet/src/device.rs @@ -27,10 +27,9 @@ use qemu_api::{ }, prelude::*, qdev::{DeviceImpl, DeviceState, Property, ResetType, ResettablePhasesImpl}, - qom::{ObjectImpl, ObjectType, ParentField, ParentInit}, - qom_isa, sysbus::{SysBusDevice, SysBusDeviceImpl}, }; +use qom::{prelude::*, ObjectImpl, ParentField, ParentInit}; use util::timer::{Timer, CLOCK_VIRTUAL, NANOSECONDS_PER_SECOND}; use crate::fw_cfg::HPETFwConfig; diff --git a/rust/meson.build b/rust/meson.build index 2ba1ea2280..043603d416 100644 --- a/rust/meson.build +++ b/rust/meson.build @@ -28,6 +28,7 @@ subdir('bits') subdir('util') subdir('migration') subdir('bql') +subdir('qom') subdir('qemu-api') subdir('hw') diff --git a/rust/migration/src/vmstate.rs b/rust/migration/src/vmstate.rs index d714aacb7e..c05c4a1fd6 100644 --- a/rust/migration/src/vmstate.rs +++ b/rust/migration/src/vmstate.rs @@ -137,7 +137,7 @@ pub const fn vmstate_varray_flag(_: PhantomData) -> VMStateFlags /// /// [`BqlCell`]: ../../bql/cell/struct.BqlCell.html /// [`BqlRefCell`]: ../../bql/cell/struct.BqlRefCell.html -/// [`Owned`]: ../../qemu_api/qom/struct.Owned.html +/// [`Owned`]: ../../qom/qom/struct.Owned.html #[macro_export] macro_rules! vmstate_of { ($struct_name:ty, $field_name:ident $([0 .. $num:ident $(* $factor:expr)?])? $(, $test_fn:expr)? $(,)?) => { diff --git a/rust/qemu-api-macros/src/lib.rs b/rust/qemu-api-macros/src/lib.rs index 67650a9a26..e643e57ebd 100644 --- a/rust/qemu-api-macros/src/lib.rs +++ b/rust/qemu-api-macros/src/lib.rs @@ -98,11 +98,11 @@ fn derive_object_or_error(input: DeriveInput) -> Result::ParentType>); + ::qom::ParentField<<#name as ::qom::ObjectImpl>::ParentType>); ::util::module_init! { MODULE_INIT_QOM => unsafe { - ::qemu_api::bindings::type_register_static(&<#name as ::qemu_api::qom::ObjectImpl>::TYPE_INFO); + ::qom::type_register_static(&<#name as ::qom::ObjectImpl>::TYPE_INFO); } } }) diff --git a/rust/qemu-api-macros/src/tests.rs b/rust/qemu-api-macros/src/tests.rs index 8e71ac6e67..76e6c57479 100644 --- a/rust/qemu-api-macros/src/tests.rs +++ b/rust/qemu-api-macros/src/tests.rs @@ -168,11 +168,11 @@ fn test_derive_object() { ::common::assert_field_type!( Foo, _unused, - ::qemu_api::qom::ParentField<::ParentType> + ::qom::ParentField<::ParentType> ); ::util::module_init! { MODULE_INIT_QOM => unsafe { - ::qemu_api::bindings::type_register_static(&::TYPE_INFO); + ::qom::type_register_static(&::TYPE_INFO); } } } diff --git a/rust/qemu-api/Cargo.toml b/rust/qemu-api/Cargo.toml index 6e9427f80c..9d11becb28 100644 --- a/rust/qemu-api/Cargo.toml +++ b/rust/qemu-api/Cargo.toml @@ -18,6 +18,7 @@ common = { path = "../common" } migration = { path = "../migration" } util = { path = "../util" } bql = { path = "../bql" } +qom = { path = "../qom" } qemu_api_macros = { path = "../qemu-api-macros" } [lints] diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index a47ee6c1a3..11e43bb646 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -22,9 +22,15 @@ foreach enum : c_bitfields _qemu_api_bindgen_args += ['--bitfield-enum', enum] endforeach -_qemu_api_bindgen_args += ['--blocklist-type', 'VMStateDescription'] +blocked_type = [ + 'ObjectClass', + 'VMStateDescription', + 'Error', +] +foreach type: blocked_type + _qemu_api_bindgen_args += ['--blocklist-type', type] +endforeach -_qemu_api_bindgen_args += ['--blocklist-type', 'Error'] # TODO: Remove this comment when the clang/libclang mismatch issue is solved. # # Rust bindings generation with `bindgen` might fail in some cases where the @@ -52,7 +58,6 @@ _qemu_api_rs = static_library( 'src/memory.rs', 'src/prelude.rs', 'src/qdev.rs', - 'src/qom.rs', 'src/sysbus.rs', ], {'.' : _qemu_api_bindings_inc_rs}, @@ -61,7 +66,7 @@ _qemu_api_rs = static_library( rust_abi: 'rust', rust_args: _qemu_api_cfg, dependencies: [anyhow_rs, bql_rs, common_rs, foreign_rs, libc_rs, migration_rs, qemu_api_macros, - util_rs, qom, hwcore, chardev], + qom_rs, util_rs, hwcore, chardev], ) qemu_api_rs = declare_dependency(link_with: [_qemu_api_rs], @@ -74,7 +79,7 @@ test('rust-qemu-api-integration', override_options: ['rust_std=2021', 'build.rust_std=2021'], rust_args: ['--test'], install: false, - dependencies: [bql_rs, common_rs, util_rs, migration_rs, qemu_api_rs]), + dependencies: [bql_rs, common_rs, util_rs, migration_rs, qom_rs, qemu_api_rs]), args: [ '--test', '--test-threads', '1', '--format', 'pretty', diff --git a/rust/qemu-api/src/bindings.rs b/rust/qemu-api/src/bindings.rs index ce00a6e0e4..525f136ae2 100644 --- a/rust/qemu-api/src/bindings.rs +++ b/rust/qemu-api/src/bindings.rs @@ -22,6 +22,7 @@ use common::Zeroable; use migration::bindings::VMStateDescription; +use qom::bindings::ObjectClass; use util::bindings::Error; #[cfg(MESON)] diff --git a/rust/qemu-api/src/chardev.rs b/rust/qemu-api/src/chardev.rs index 2ec90cc0b2..072d806e4a 100644 --- a/rust/qemu-api/src/chardev.rs +++ b/rust/qemu-api/src/chardev.rs @@ -20,8 +20,9 @@ use std::{ use bql::{BqlRefCell, BqlRefMut}; use common::{callbacks::FnCall, errno, Opaque}; +use qom::prelude::*; -use crate::{bindings, prelude::*}; +use crate::bindings; /// A safe wrapper around [`bindings::Chardev`]. #[repr(transparent)] diff --git a/rust/qemu-api/src/irq.rs b/rust/qemu-api/src/irq.rs index 3063fbe97a..fead2bbe8e 100644 --- a/rust/qemu-api/src/irq.rs +++ b/rust/qemu-api/src/irq.rs @@ -12,12 +12,9 @@ use std::{ use bql::BqlCell; use common::Opaque; +use qom::{prelude::*, ObjectClass}; -use crate::{ - bindings::{self, qemu_set_irq}, - prelude::*, - qom::ObjectClass, -}; +use crate::bindings::{self, qemu_set_irq}; /// An opaque wrapper around [`bindings::IRQState`]. #[repr(transparent)] @@ -36,7 +33,7 @@ pub struct IRQState(Opaque); /// /// Interrupts are implemented as a pointer to the interrupt "sink", which has /// type [`IRQState`]. A device exposes its source as a QOM link property using -/// a function such as [`SysBusDeviceMethods::init_irq`], and +/// a function such as [`crate::sysbus::SysBusDeviceMethods::init_irq`], and /// initially leaves the pointer to a NULL value, representing an unconnected /// interrupt. To connect it, whoever creates the device fills the pointer with /// the sink's `IRQState *`, for example using `sysbus_connect_irq`. Because @@ -114,4 +111,5 @@ unsafe impl ObjectType for IRQState { const TYPE_NAME: &'static CStr = unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_IRQ) }; } + qom_isa!(IRQState: Object); diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs index 6cd9e5b990..0541050e66 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -17,7 +17,6 @@ pub mod chardev; pub mod irq; pub mod memory; pub mod qdev; -pub mod qom; pub mod sysbus; // Allow proc-macros to refer to `::qemu_api` inside the `qemu_api` crate (this diff --git a/rust/qemu-api/src/memory.rs b/rust/qemu-api/src/memory.rs index f790cb5fd2..ecbbd9b604 100644 --- a/rust/qemu-api/src/memory.rs +++ b/rust/qemu-api/src/memory.rs @@ -11,11 +11,9 @@ use std::{ pub use bindings::{hwaddr, MemTxAttrs}; use common::{callbacks::FnCall, uninit::MaybeUninitField, zeroable::Zeroable, Opaque}; +use qom::prelude::*; -use crate::{ - bindings::{self, device_endian, memory_region_init_io}, - prelude::*, -}; +use crate::bindings::{self, device_endian, memory_region_init_io}; pub struct MemoryRegionOps( bindings::MemoryRegionOps, @@ -186,6 +184,7 @@ unsafe impl ObjectType for MemoryRegion { const TYPE_NAME: &'static CStr = unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_MEMORY_REGION) }; } + qom_isa!(MemoryRegion: Object); /// A special `MemTxAttrs` constant, used to indicate that no memory diff --git a/rust/qemu-api/src/prelude.rs b/rust/qemu-api/src/prelude.rs index 9da7313016..9e9d1c8247 100644 --- a/rust/qemu-api/src/prelude.rs +++ b/rust/qemu-api/src/prelude.rs @@ -6,15 +6,4 @@ pub use crate::qdev::DeviceMethods; -pub use crate::qom::InterfaceType; -pub use crate::qom::IsA; -pub use crate::qom::Object; -pub use crate::qom::ObjectCast; -pub use crate::qom::ObjectClassMethods; -pub use crate::qom::ObjectDeref; -pub use crate::qom::ObjectMethods; -pub use crate::qom::ObjectType; - -pub use crate::qom_isa; - pub use crate::sysbus::SysBusDeviceMethods; diff --git a/rust/qemu-api/src/qdev.rs b/rust/qemu-api/src/qdev.rs index 74a82b8710..3daf9dda2b 100644 --- a/rust/qemu-api/src/qdev.rs +++ b/rust/qemu-api/src/qdev.rs @@ -12,14 +12,13 @@ use std::{ pub use bindings::{ClockEvent, DeviceClass, Property, ResetType}; use common::{callbacks::FnCall, Opaque}; use migration::{impl_vmstate_c_struct, VMStateDescription}; +use qom::{prelude::*, ObjectClass, ObjectImpl, Owned, ParentInit}; use util::{Error, Result}; use crate::{ bindings::{self, qdev_init_gpio_in, qdev_init_gpio_out, ResettableClass}, chardev::Chardev, irq::InterruptSource, - prelude::*, - qom::{ObjectClass, ObjectImpl, Owned, ParentInit}, }; /// A safe wrapper around [`bindings::Clock`]. @@ -291,6 +290,7 @@ unsafe impl ObjectType for DeviceState { const TYPE_NAME: &'static CStr = unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_DEVICE) }; } + qom_isa!(DeviceState: Object); /// Initialization methods take a [`ParentInit`] and can be called as @@ -453,6 +453,7 @@ unsafe impl ObjectType for Clock { const TYPE_NAME: &'static CStr = unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_CLOCK) }; } + qom_isa!(Clock: Object); impl_vmstate_c_struct!(Clock, bindings::vmstate_clock); diff --git a/rust/qemu-api/src/qom.rs b/rust/qemu-api/src/qom.rs deleted file mode 100644 index 032701af65..0000000000 --- a/rust/qemu-api/src/qom.rs +++ /dev/null @@ -1,951 +0,0 @@ -// Copyright 2024, Linaro Limited -// Author(s): Manos Pitsidianakis -// SPDX-License-Identifier: GPL-2.0-or-later - -//! Bindings to access QOM functionality from Rust. -//! -//! The QEMU Object Model (QOM) provides inheritance and dynamic typing for QEMU -//! devices. This module makes QOM's features available in Rust through three -//! main mechanisms: -//! -//! * Automatic creation and registration of `TypeInfo` for classes that are -//! written in Rust, as well as mapping between Rust traits and QOM vtables. -//! -//! * Type-safe casting between parent and child classes, through the [`IsA`] -//! trait and methods such as [`upcast`](ObjectCast::upcast) and -//! [`downcast`](ObjectCast::downcast). -//! -//! * Automatic delegation of parent class methods to child classes. When a -//! trait uses [`IsA`] as a bound, its contents become available to all child -//! classes through blanket implementations. This works both for class methods -//! and for instance methods accessed through references or smart pointers. -//! -//! # Structure of a class -//! -//! A leaf class only needs a struct holding instance state. The struct must -//! implement the [`ObjectType`] and [`IsA`] traits, as well as any `*Impl` -//! traits that exist for its superclasses. -//! -//! If a class has subclasses, it will also provide a struct for instance data, -//! with the same characteristics as for concrete classes, but it also needs -//! additional components to support virtual methods: -//! -//! * a struct for class data, for example `DeviceClass`. This corresponds to -//! the C "class struct" and holds the vtable that is used by instances of the -//! class and its subclasses. It must start with its parent's class struct. -//! -//! * a trait for virtual method implementations, for example `DeviceImpl`. -//! Child classes implement this trait to provide their own behavior for -//! virtual methods. The trait's methods take `&self` to access instance data. -//! The traits have the appropriate specialization of `IsA<>` as a supertrait, -//! for example `IsA` for `DeviceImpl`. -//! -//! * a trait for instance methods, for example `DeviceMethods`. This trait is -//! automatically implemented for any reference or smart pointer to a device -//! instance. It calls into the vtable provides access across all subclasses -//! to methods defined for the class. -//! -//! * optionally, a trait for class methods, for example `DeviceClassMethods`. -//! This provides access to class-wide functionality that doesn't depend on -//! instance data. Like instance methods, these are automatically inherited by -//! child classes. -//! -//! # Class structures -//! -//! Each QOM class that has virtual methods describes them in a -//! _class struct_. Class structs include a parent field corresponding -//! to the vtable of the parent class, all the way up to [`ObjectClass`]. -//! -//! As mentioned above, virtual methods are defined via traits such as -//! `DeviceImpl`. Class structs do not define any trait but, conventionally, -//! all of them have a `class_init` method to initialize the virtual methods -//! based on the trait and then call the same method on the superclass. -//! -//! ```ignore -//! impl YourSubclassClass -//! { -//! pub fn class_init(&mut self) { -//! ... -//! klass.parent_class::class_init(); -//! } -//! } -//! ``` -//! -//! If a class implements a QOM interface. In that case, the function must -//! contain, for each interface, an extra forwarding call as follows: -//! -//! ```ignore -//! ResettableClass::cast::(self).class_init::(); -//! ``` -//! -//! These `class_init` functions are methods on the class rather than a trait, -//! because the bound on `T` (`DeviceImpl` in this case), will change for every -//! class struct. The functions are pointed to by the -//! [`ObjectImpl::CLASS_INIT`] function pointer. While there is no default -//! implementation, in most cases it will be enough to write it as follows: -//! -//! ```ignore -//! const CLASS_INIT: fn(&mut Self::Class)> = Self::Class::class_init::; -//! ``` -//! -//! This design incurs a small amount of code duplication but, by not using -//! traits, it allows the flexibility of implementing bindings in any crate, -//! without incurring into violations of orphan rules for traits. - -use std::{ - ffi::{c_void, CStr}, - fmt, - marker::PhantomData, - mem::{ManuallyDrop, MaybeUninit}, - ops::{Deref, DerefMut}, - ptr::NonNull, -}; - -pub use bindings::ObjectClass; -use common::Opaque; -use migration::impl_vmstate_pointer; - -use crate::bindings::{ - self, object_class_dynamic_cast, object_dynamic_cast, object_get_class, object_get_typename, - object_new, object_ref, object_unref, TypeInfo, -}; - -/// A safe wrapper around [`bindings::Object`]. -#[repr(transparent)] -#[derive(Debug, qemu_api_macros::Wrapper)] -pub struct Object(Opaque); - -unsafe impl Send for Object {} -unsafe impl Sync for Object {} - -/// Marker trait: `Self` can be statically upcasted to `P` (i.e. `P` is a direct -/// or indirect parent of `Self`). -/// -/// # Safety -/// -/// The struct `Self` must be `#[repr(C)]` and must begin, directly or -/// indirectly, with a field of type `P`. This ensures that invalid casts, -/// which rely on `IsA<>` for static checking, are rejected at compile time. -pub unsafe trait IsA: ObjectType {} - -// SAFETY: it is always safe to cast to your own type -unsafe impl IsA for T {} - -/// Macro to mark superclasses of QOM classes. This enables type-safe -/// up- and downcasting. -/// -/// # Safety -/// -/// This macro is a thin wrapper around the [`IsA`] trait and performs -/// no checking whatsoever of what is declared. It is the caller's -/// responsibility to have $struct begin, directly or indirectly, with -/// a field of type `$parent`. -#[macro_export] -macro_rules! qom_isa { - ($struct:ty : $($parent:ty),* ) => { - $( - // SAFETY: it is the caller responsibility to have $parent as the - // first field - unsafe impl $crate::qom::IsA<$parent> for $struct {} - - impl AsRef<$parent> for $struct { - fn as_ref(&self) -> &$parent { - // SAFETY: follows the same rules as for IsA, which is - // declared above. - let ptr: *const Self = self; - unsafe { &*ptr.cast::<$parent>() } - } - } - )* - }; -} - -/// This is the same as [`ManuallyDrop`](std::mem::ManuallyDrop), though -/// it hides the standard methods of `ManuallyDrop`. -/// -/// The first field of an `ObjectType` must be of type `ParentField`. -/// (Technically, this is only necessary if there is at least one Rust -/// superclass in the hierarchy). This is to ensure that the parent field is -/// dropped after the subclass; this drop order is enforced by the C -/// `object_deinit` function. -/// -/// # Examples -/// -/// ```ignore -/// #[repr(C)] -/// #[derive(qemu_api_macros::Object)] -/// pub struct MyDevice { -/// parent: ParentField, -/// ... -/// } -/// ``` -#[derive(Debug)] -#[repr(transparent)] -pub struct ParentField(std::mem::ManuallyDrop); - -impl Deref for ParentField { - type Target = T; - - #[inline(always)] - fn deref(&self) -> &Self::Target { - &self.0 - } -} - -impl DerefMut for ParentField { - #[inline(always)] - fn deref_mut(&mut self) -> &mut Self::Target { - &mut self.0 - } -} - -impl fmt::Display for ParentField { - #[inline(always)] - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> { - self.0.fmt(f) - } -} - -/// This struct knows that the superclasses of the object have already been -/// initialized. -/// -/// The declaration of `ParentInit` is.. *"a kind of magic"*. It uses a -/// technique that is found in several crates, the main ones probably being -/// `ghost-cell` (in fact it was introduced by the [`GhostCell` paper](https://plv.mpi-sws.org/rustbelt/ghostcell/)) -/// and `generativity`. -/// -/// The `PhantomData` makes the `ParentInit` type *invariant* with respect to -/// the lifetime argument `'init`. This, together with the `for<'...>` in -/// `[ParentInit::with]`, block any attempt of the compiler to be creative when -/// operating on types of type `ParentInit` and to extend their lifetimes. In -/// particular, it ensures that the `ParentInit` cannot be made to outlive the -/// `rust_instance_init()` function that creates it, and therefore that the -/// `&'init T` reference is valid. -/// -/// This implementation of the same concept, without the QOM baggage, can help -/// understanding the effect: -/// -/// ``` -/// use std::marker::PhantomData; -/// -/// #[derive(PartialEq, Eq)] -/// pub struct Jail<'closure, T: Copy>(&'closure T, PhantomData &'closure ()>); -/// -/// impl<'closure, T: Copy> Jail<'closure, T> { -/// fn get(&self) -> T { -/// *self.0 -/// } -/// -/// #[inline] -/// fn with(v: T, f: impl for<'id> FnOnce(Jail<'id, T>) -> U) -> U { -/// let parent_init = Jail(&v, PhantomData); -/// f(parent_init) -/// } -/// } -/// ``` -/// -/// It's impossible to escape the `Jail`; `token1` cannot be moved out of the -/// closure: -/// -/// ```ignore -/// let x = 42; -/// let escape = Jail::with(&x, |token1| { -/// println!("{}", token1.get()); -/// // fails to compile... -/// token1 -/// }); -/// // ... so you cannot do this: -/// println!("{}", escape.get()); -/// ``` -/// -/// Likewise, in the QOM case the `ParentInit` cannot be moved out of -/// `instance_init()`. Without this trick it would be possible to stash a -/// `ParentInit` and use it later to access uninitialized memory. -/// -/// Here is another example, showing how separately-created "identities" stay -/// isolated: -/// -/// ```ignore -/// impl<'closure, T: Copy> Clone for Jail<'closure, T> { -/// fn clone(&self) -> Jail<'closure, T> { -/// Jail(self.0, PhantomData) -/// } -/// } -/// -/// fn main() { -/// Jail::with(42, |token1| { -/// // this works and returns true: the clone has the same "identity" -/// println!("{}", token1 == token1.clone()); -/// Jail::with(42, |token2| { -/// // here the outer token remains accessible... -/// println!("{}", token1.get()); -/// // ... but the two are separate: this fails to compile: -/// println!("{}", token1 == token2); -/// }); -/// }); -/// } -/// ``` -pub struct ParentInit<'init, T>( - &'init mut MaybeUninit, - PhantomData &'init ()>, -); - -impl<'init, T> ParentInit<'init, T> { - #[inline] - pub fn with(obj: &'init mut MaybeUninit, f: impl for<'id> FnOnce(ParentInit<'id, T>)) { - let parent_init = ParentInit(obj, PhantomData); - f(parent_init) - } -} - -impl ParentInit<'_, T> { - /// Return the receiver as a mutable raw pointer to Object. - /// - /// # Safety - /// - /// Fields beyond `Object` could be uninitialized and it's your - /// responsibility to avoid that they're used when the pointer is - /// dereferenced, either directly or through a cast. - pub const fn as_object_mut_ptr(&self) -> *mut bindings::Object { - self.as_object_ptr().cast_mut() - } - - /// Return the receiver as a mutable raw pointer to Object. - /// - /// # Safety - /// - /// Fields beyond `Object` could be uninitialized and it's your - /// responsibility to avoid that they're used when the pointer is - /// dereferenced, either directly or through a cast. - pub const fn as_object_ptr(&self) -> *const bindings::Object { - self.0.as_ptr().cast() - } -} - -impl<'a, T: ObjectImpl> ParentInit<'a, T> { - /// Convert from a derived type to one of its parent types, which - /// have already been initialized. - /// - /// # Safety - /// - /// Structurally this is always a safe operation; the [`IsA`] trait - /// provides static verification trait that `Self` dereferences to `U` or - /// a child of `U`, and only parent types of `T` are allowed. - /// - /// However, while the fields of the resulting reference are initialized, - /// calls might use uninitialized fields of the subclass. It is your - /// responsibility to avoid this. - pub const unsafe fn upcast(&self) -> &'a U - where - T::ParentType: IsA, - { - // SAFETY: soundness is declared via IsA, which is an unsafe trait; - // the parent has been initialized before `instance_init `is called - unsafe { &*(self.0.as_ptr().cast::()) } - } - - /// Convert from a derived type to one of its parent types, which - /// have already been initialized. - /// - /// # Safety - /// - /// Structurally this is always a safe operation; the [`IsA`] trait - /// provides static verification trait that `Self` dereferences to `U` or - /// a child of `U`, and only parent types of `T` are allowed. - /// - /// However, while the fields of the resulting reference are initialized, - /// calls might use uninitialized fields of the subclass. It is your - /// responsibility to avoid this. - pub unsafe fn upcast_mut(&mut self) -> &'a mut U - where - T::ParentType: IsA, - { - // SAFETY: soundness is declared via IsA, which is an unsafe trait; - // the parent has been initialized before `instance_init `is called - unsafe { &mut *(self.0.as_mut_ptr().cast::()) } - } -} - -impl Deref for ParentInit<'_, T> { - type Target = MaybeUninit; - - fn deref(&self) -> &Self::Target { - self.0 - } -} - -impl DerefMut for ParentInit<'_, T> { - fn deref_mut(&mut self) -> &mut Self::Target { - self.0 - } -} - -unsafe extern "C" fn rust_instance_init(obj: *mut bindings::Object) { - let mut state = NonNull::new(obj).unwrap().cast::>(); - - // SAFETY: obj is an instance of T, since rust_instance_init - // is called from QOM core as the instance_init function - // for class T - unsafe { - ParentInit::with(state.as_mut(), |parent_init| { - T::INSTANCE_INIT.unwrap()(parent_init); - }); - } -} - -unsafe extern "C" fn rust_instance_post_init(obj: *mut bindings::Object) { - let state = NonNull::new(obj).unwrap().cast::(); - // SAFETY: obj is an instance of T, since rust_instance_post_init - // is called from QOM core as the instance_post_init function - // for class T - T::INSTANCE_POST_INIT.unwrap()(unsafe { state.as_ref() }); -} - -unsafe extern "C" fn rust_class_init( - klass: *mut ObjectClass, - _data: *const c_void, -) { - let mut klass = NonNull::new(klass) - .unwrap() - .cast::<::Class>(); - // SAFETY: klass is a T::Class, since rust_class_init - // is called from QOM core as the class_init function - // for class T - ::CLASS_INIT(unsafe { klass.as_mut() }) -} - -unsafe extern "C" fn drop_object(obj: *mut bindings::Object) { - // SAFETY: obj is an instance of T, since drop_object is called - // from the QOM core function object_deinit() as the instance_finalize - // function for class T. Note that while object_deinit() will drop the - // superclass field separately after this function returns, `T` must - // implement the unsafe trait ObjectType; the safety rules for the - // trait mandate that the parent field is manually dropped. - unsafe { std::ptr::drop_in_place(obj.cast::()) } -} - -/// Trait exposed by all structs corresponding to QOM objects. -/// -/// # Safety -/// -/// For classes declared in C: -/// -/// - `Class` and `TYPE` must match the data in the `TypeInfo`; -/// -/// - the first field of the struct must be of the instance type corresponding -/// to the superclass, as declared in the `TypeInfo` -/// -/// - likewise, the first field of the `Class` struct must be of the class type -/// corresponding to the superclass -/// -/// For classes declared in Rust and implementing [`ObjectImpl`]: -/// -/// - the struct must be `#[repr(C)]`; -/// -/// - the first field of the struct must be of type -/// [`ParentField`](ParentField), where `T` is the parent type -/// [`ObjectImpl::ParentType`] -/// -/// - the first field of the `Class` must be of the class struct corresponding -/// to the superclass, which is `ObjectImpl::ParentType::Class`. `ParentField` -/// is not needed here. -/// -/// In both cases, having a separate class type is not necessary if the subclass -/// does not add any field. -pub unsafe trait ObjectType: Sized { - /// The QOM class object corresponding to this struct. This is used - /// to automatically generate a `class_init` method. - type Class; - - /// The name of the type, which can be passed to `object_new()` to - /// generate an instance of this type. - const TYPE_NAME: &'static CStr; - - /// Return the receiver as an Object. This is always safe, even - /// if this type represents an interface. - fn as_object(&self) -> &Object { - unsafe { &*self.as_ptr().cast() } - } - - /// Return the receiver as a const raw pointer to Object. - /// This is preferable to `as_object_mut_ptr()` if a C - /// function only needs a `const Object *`. - fn as_object_ptr(&self) -> *const bindings::Object { - self.as_object().as_ptr() - } - - /// Return the receiver as a mutable raw pointer to Object. - /// - /// # Safety - /// - /// This cast is always safe, but because the result is mutable - /// and the incoming reference is not, this should only be used - /// for calls to C functions, and only if needed. - unsafe fn as_object_mut_ptr(&self) -> *mut bindings::Object { - self.as_object().as_mut_ptr() - } -} - -/// Trait exposed by all structs corresponding to QOM interfaces. -/// Unlike `ObjectType`, it is implemented on the class type (which provides -/// the vtable for the interfaces). -/// -/// # Safety -/// -/// `TYPE` must match the contents of the `TypeInfo` as found in the C code; -/// right now, interfaces can only be declared in C. -pub unsafe trait InterfaceType: Sized { - /// The name of the type, which can be passed to - /// `object_class_dynamic_cast()` to obtain the pointer to the vtable - /// for this interface. - const TYPE_NAME: &'static CStr; - - /// Return the vtable for the interface; `U` is the type that - /// lists the interface in its `TypeInfo`. - /// - /// # Examples - /// - /// This function is usually called by a `class_init` method in `U::Class`. - /// For example, `DeviceClass::class_init` initializes its `Resettable` - /// interface as follows: - /// - /// ```ignore - /// ResettableClass::cast::(self).class_init::(); - /// ``` - /// - /// where `T` is the concrete subclass that is being initialized. - /// - /// # Panics - /// - /// Panic if the incoming argument if `T` does not implement the interface. - fn cast(klass: &mut U::Class) -> &mut Self { - unsafe { - // SAFETY: upcasting to ObjectClass is always valid, and the - // return type is either NULL or the argument itself - let result: *mut Self = object_class_dynamic_cast( - (klass as *mut U::Class).cast(), - Self::TYPE_NAME.as_ptr(), - ) - .cast(); - result.as_mut().unwrap() - } - } -} - -/// This trait provides safe casting operations for QOM objects to raw pointers, -/// to be used for example for FFI. The trait can be applied to any kind of -/// reference or smart pointers, and enforces correctness through the [`IsA`] -/// trait. -pub trait ObjectDeref: Deref -where - Self::Target: ObjectType, -{ - /// Convert to a const Rust pointer, to be used for example for FFI. - /// The target pointer type must be the type of `self` or a superclass - fn as_ptr(&self) -> *const U - where - Self::Target: IsA, - { - let ptr: *const Self::Target = self.deref(); - ptr.cast::() - } - - /// Convert to a mutable Rust pointer, to be used for example for FFI. - /// The target pointer type must be the type of `self` or a superclass. - /// Used to implement interior mutability for objects. - /// - /// # Safety - /// - /// This method is safe because only the actual dereference of the pointer - /// has to be unsafe. Bindings to C APIs will use it a lot, but care has - /// to be taken because it overrides the const-ness of `&self`. - fn as_mut_ptr(&self) -> *mut U - where - Self::Target: IsA, - { - #[allow(clippy::as_ptr_cast_mut)] - { - self.as_ptr::().cast_mut() - } - } -} - -/// Trait that adds extra functionality for `&T` where `T` is a QOM -/// object type. Allows conversion to/from C objects in generic code. -pub trait ObjectCast: ObjectDeref + Copy -where - Self::Target: ObjectType, -{ - /// Safely convert from a derived type to one of its parent types. - /// - /// This is always safe; the [`IsA`] trait provides static verification - /// trait that `Self` dereferences to `U` or a child of `U`. - fn upcast<'a, U: ObjectType>(self) -> &'a U - where - Self::Target: IsA, - Self: 'a, - { - // SAFETY: soundness is declared via IsA, which is an unsafe trait - unsafe { self.unsafe_cast::() } - } - - /// Attempt to convert to a derived type. - /// - /// Returns `None` if the object is not actually of type `U`. This is - /// verified at runtime by checking the object's type information. - fn downcast<'a, U: IsA>(self) -> Option<&'a U> - where - Self: 'a, - { - self.dynamic_cast::() - } - - /// Attempt to convert between any two types in the QOM hierarchy. - /// - /// Returns `None` if the object is not actually of type `U`. This is - /// verified at runtime by checking the object's type information. - fn dynamic_cast<'a, U: ObjectType>(self) -> Option<&'a U> - where - Self: 'a, - { - unsafe { - // SAFETY: upcasting to Object is always valid, and the - // return type is either NULL or the argument itself - let result: *const U = - object_dynamic_cast(self.as_object_mut_ptr(), U::TYPE_NAME.as_ptr()).cast(); - - result.as_ref() - } - } - - /// Convert to any QOM type without verification. - /// - /// # Safety - /// - /// What safety? You need to know yourself that the cast is correct; only - /// use when performance is paramount. It is still better than a raw - /// pointer `cast()`, which does not even check that you remain in the - /// realm of QOM `ObjectType`s. - /// - /// `unsafe_cast::()` is always safe. - unsafe fn unsafe_cast<'a, U: ObjectType>(self) -> &'a U - where - Self: 'a, - { - unsafe { &*(self.as_ptr::().cast::()) } - } -} - -impl ObjectDeref for &T {} -impl ObjectCast for &T {} - -impl ObjectDeref for &mut T {} - -/// Trait a type must implement to be registered with QEMU. -pub trait ObjectImpl: ObjectType + IsA { - /// The parent of the type. This should match the first field of the - /// struct that implements `ObjectImpl`, minus the `ParentField<_>` wrapper. - type ParentType: ObjectType; - - /// Whether the object can be instantiated - const ABSTRACT: bool = false; - - /// Function that is called to initialize an object. The parent class will - /// have already been initialized so the type is only responsible for - /// initializing its own members. - /// - /// FIXME: The argument is not really a valid reference. `&mut - /// MaybeUninit` would be a better description. - const INSTANCE_INIT: Option)> = None; - - /// Function that is called to finish initialization of an object, once - /// `INSTANCE_INIT` functions have been called. - const INSTANCE_POST_INIT: Option = None; - - /// Called on descendant classes after all parent class initialization - /// has occurred, but before the class itself is initialized. This - /// is only useful if a class is not a leaf, and can be used to undo - /// the effects of copying the contents of the parent's class struct - /// to the descendants. - const CLASS_BASE_INIT: Option< - unsafe extern "C" fn(klass: *mut ObjectClass, data: *const c_void), - > = None; - - const TYPE_INFO: TypeInfo = TypeInfo { - name: Self::TYPE_NAME.as_ptr(), - parent: Self::ParentType::TYPE_NAME.as_ptr(), - instance_size: core::mem::size_of::(), - instance_align: core::mem::align_of::(), - instance_init: match Self::INSTANCE_INIT { - None => None, - Some(_) => Some(rust_instance_init::), - }, - instance_post_init: match Self::INSTANCE_POST_INIT { - None => None, - Some(_) => Some(rust_instance_post_init::), - }, - instance_finalize: Some(drop_object::), - abstract_: Self::ABSTRACT, - class_size: core::mem::size_of::(), - class_init: Some(rust_class_init::), - class_base_init: Self::CLASS_BASE_INIT, - class_data: core::ptr::null(), - interfaces: core::ptr::null(), - }; - - // methods on ObjectClass - const UNPARENT: Option = None; - - /// Store into the argument the virtual method implementations - /// for `Self`. On entry, the virtual method pointers are set to - /// the default values coming from the parent classes; the function - /// can change them to override virtual methods of a parent class. - /// - /// Usually defined simply as `Self::Class::class_init::`; - /// however a default implementation cannot be included here, because the - /// bounds that the `Self::Class::class_init` method places on `Self` are - /// not known in advance. - /// - /// # Safety - /// - /// While `klass`'s parent class is initialized on entry, the other fields - /// are all zero; it is therefore assumed that all fields in `T` can be - /// zeroed, otherwise it would not be possible to provide the class as a - /// `&mut T`. TODO: it may be possible to add an unsafe trait that checks - /// that all fields *after the parent class* (but not the parent class - /// itself) are Zeroable. This unsafe trait can be added via a derive - /// macro. - const CLASS_INIT: fn(&mut Self::Class); -} - -/// # Safety -/// -/// We expect the FFI user of this function to pass a valid pointer that -/// can be downcasted to type `T`. We also expect the device is -/// readable/writeable from one thread at any time. -unsafe extern "C" fn rust_unparent_fn(dev: *mut bindings::Object) { - let state = NonNull::new(dev).unwrap().cast::(); - T::UNPARENT.unwrap()(unsafe { state.as_ref() }); -} - -impl ObjectClass { - /// Fill in the virtual methods of `ObjectClass` based on the definitions in - /// the `ObjectImpl` trait. - pub fn class_init(&mut self) { - if ::UNPARENT.is_some() { - self.unparent = Some(rust_unparent_fn::); - } - } -} - -unsafe impl ObjectType for Object { - type Class = ObjectClass; - const TYPE_NAME: &'static CStr = - unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_OBJECT) }; -} - -/// A reference-counted pointer to a QOM object. -/// -/// `Owned` wraps `T` with automatic reference counting. It increases the -/// reference count when created via [`Owned::from`] or cloned, and decreases -/// it when dropped. This ensures that the reference count remains elevated -/// as long as any `Owned` references to it exist. -/// -/// `Owned` can be used for two reasons: -/// * because the lifetime of the QOM object is unknown and someone else could -/// take a reference (similar to `Arc`, for example): in this case, the -/// object can escape and outlive the Rust struct that contains the `Owned` -/// field; -/// -/// * to ensure that the object stays alive until after `Drop::drop` is called -/// on the Rust struct: in this case, the object will always die together with -/// the Rust struct that contains the `Owned` field. -/// -/// Child properties are an example of the second case: in C, an object that -/// is created with `object_initialize_child` will die *before* -/// `instance_finalize` is called, whereas Rust expects the struct to have valid -/// contents when `Drop::drop` is called. Therefore Rust structs that have -/// child properties need to keep a reference to the child object. Right now -/// this can be done with `Owned`; in the future one might have a separate -/// `Child<'parent, T>` smart pointer that keeps a reference to a `T`, like -/// `Owned`, but does not allow cloning. -/// -/// Note that dropping an `Owned` requires the big QEMU lock to be taken. -#[repr(transparent)] -#[derive(PartialEq, Eq, Hash, PartialOrd, Ord)] -pub struct Owned(NonNull); - -// The following rationale for safety is taken from Linux's kernel::sync::Arc. - -// SAFETY: It is safe to send `Owned` to another thread when the underlying -// `T` is `Sync` because it effectively means sharing `&T` (which is safe -// because `T` is `Sync`); additionally, it needs `T` to be `Send` because any -// thread that has an `Owned` may ultimately access `T` using a -// mutable reference when the reference count reaches zero and `T` is dropped. -unsafe impl Send for Owned {} - -// SAFETY: It is safe to send `&Owned` to another thread when the underlying -// `T` is `Sync` because it effectively means sharing `&T` (which is safe -// because `T` is `Sync`); additionally, it needs `T` to be `Send` because any -// thread that has a `&Owned` may clone it and get an `Owned` on that -// thread, so the thread may ultimately access `T` using a mutable reference -// when the reference count reaches zero and `T` is dropped. -unsafe impl Sync for Owned {} - -impl Owned { - /// Convert a raw C pointer into an owned reference to the QOM - /// object it points to. The object's reference count will be - /// decreased when the `Owned` is dropped. - /// - /// # Panics - /// - /// Panics if `ptr` is NULL. - /// - /// # Safety - /// - /// The caller must indeed own a reference to the QOM object. - /// The object must not be embedded in another unless the outer - /// object is guaranteed to have a longer lifetime. - /// - /// A raw pointer obtained via [`Owned::into_raw()`] can always be passed - /// back to `from_raw()` (assuming the original `Owned` was valid!), - /// since the owned reference remains there between the calls to - /// `into_raw()` and `from_raw()`. - pub unsafe fn from_raw(ptr: *const T) -> Self { - // SAFETY NOTE: while NonNull requires a mutable pointer, only - // Deref is implemented so the pointer passed to from_raw - // remains const - Owned(NonNull::new(ptr.cast_mut()).unwrap()) - } - - /// Obtain a raw C pointer from a reference. `src` is consumed - /// and the reference is leaked. - #[allow(clippy::missing_const_for_fn)] - pub fn into_raw(src: Owned) -> *mut T { - let src = ManuallyDrop::new(src); - src.0.as_ptr() - } - - /// Increase the reference count of a QOM object and return - /// a new owned reference to it. - /// - /// # Safety - /// - /// The object must not be embedded in another, unless the outer - /// object is guaranteed to have a longer lifetime. - pub unsafe fn from(obj: &T) -> Self { - unsafe { - object_ref(obj.as_object_mut_ptr().cast::()); - - // SAFETY NOTE: while NonNull requires a mutable pointer, only - // Deref is implemented so the reference passed to from_raw - // remains shared - Owned(NonNull::new_unchecked(obj.as_mut_ptr())) - } - } -} - -impl Clone for Owned { - fn clone(&self) -> Self { - // SAFETY: creation method is unsafe; whoever calls it has - // responsibility that the pointer is valid, and remains valid - // throughout the lifetime of the `Owned` and its clones. - unsafe { Owned::from(self.deref()) } - } -} - -impl Deref for Owned { - type Target = T; - - fn deref(&self) -> &Self::Target { - // SAFETY: creation method is unsafe; whoever calls it has - // responsibility that the pointer is valid, and remains valid - // throughout the lifetime of the `Owned` and its clones. - // With that guarantee, reference counting ensures that - // the object remains alive. - unsafe { &*self.0.as_ptr() } - } -} -impl ObjectDeref for Owned {} - -impl Drop for Owned { - fn drop(&mut self) { - assert!(bql::is_locked()); - // SAFETY: creation method is unsafe, and whoever calls it has - // responsibility that the pointer is valid, and remains valid - // throughout the lifetime of the `Owned` and its clones. - unsafe { - object_unref(self.as_object_mut_ptr().cast::()); - } - } -} - -impl> fmt::Debug for Owned { - fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { - self.deref().debug_fmt(f) - } -} - -/// Trait for class methods exposed by the Object class. The methods can be -/// called on all objects that have the trait `IsA`. -/// -/// The trait should only be used through the blanket implementation, -/// which guarantees safety via `IsA` -pub trait ObjectClassMethods: IsA { - /// Return a new reference counted instance of this class - fn new() -> Owned { - assert!(bql::is_locked()); - // SAFETY: the object created by object_new is allocated on - // the heap and has a reference count of 1 - unsafe { - let raw_obj = object_new(Self::TYPE_NAME.as_ptr()); - let obj = Object::from_raw(raw_obj).unsafe_cast::(); - Owned::from_raw(obj) - } - } -} - -/// Trait for methods exposed by the Object class. The methods can be -/// called on all objects that have the trait `IsA`. -/// -/// The trait should only be used through the blanket implementation, -/// which guarantees safety via `IsA` -pub trait ObjectMethods: ObjectDeref -where - Self::Target: IsA, -{ - /// Return the name of the type of `self` - fn typename(&self) -> std::borrow::Cow<'_, str> { - let obj = self.upcast::(); - // SAFETY: safety of this is the requirement for implementing IsA - // The result of the C API has static lifetime - unsafe { - let p = object_get_typename(obj.as_mut_ptr()); - CStr::from_ptr(p).to_string_lossy() - } - } - - fn get_class(&self) -> &'static ::Class { - let obj = self.upcast::(); - - // SAFETY: all objects can call object_get_class; the actual class - // type is guaranteed by the implementation of `ObjectType` and - // `ObjectImpl`. - let klass: &'static ::Class = - unsafe { &*object_get_class(obj.as_mut_ptr()).cast() }; - - klass - } - - /// Convenience function for implementing the Debug trait - fn debug_fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { - f.debug_tuple(&self.typename()) - .field(&(self as *const Self)) - .finish() - } -} - -impl ObjectClassMethods for T where T: IsA {} -impl ObjectMethods for R where R::Target: IsA {} - -impl_vmstate_pointer!(Owned where T: VMState + ObjectType); diff --git a/rust/qemu-api/src/sysbus.rs b/rust/qemu-api/src/sysbus.rs index b21883246e..b883d7eaf1 100644 --- a/rust/qemu-api/src/sysbus.rs +++ b/rust/qemu-api/src/sysbus.rs @@ -8,14 +8,13 @@ use std::{ffi::CStr, ptr::addr_of_mut}; pub use bindings::SysBusDeviceClass; use common::Opaque; +use qom::{prelude::*, Owned}; use crate::{ bindings, irq::{IRQState, InterruptSource}, memory::MemoryRegion, - prelude::*, qdev::{DeviceImpl, DeviceState}, - qom::Owned, }; /// A safe wrapper around [`bindings::SysBusDevice`]. @@ -31,6 +30,7 @@ unsafe impl ObjectType for SysBusDevice { const TYPE_NAME: &'static CStr = unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_SYS_BUS_DEVICE) }; } + qom_isa!(SysBusDevice: DeviceState, Object); // TODO: add virtual methods diff --git a/rust/qemu-api/tests/tests.rs b/rust/qemu-api/tests/tests.rs index e72ba08aef..f2e5eb9f4f 100644 --- a/rust/qemu-api/tests/tests.rs +++ b/rust/qemu-api/tests/tests.rs @@ -7,11 +7,10 @@ use std::{ffi::CStr, ptr::addr_of}; use bql::BqlCell; use migration::{VMStateDescription, VMStateDescriptionBuilder}; use qemu_api::{ - prelude::*, qdev::{DeviceImpl, DeviceState, ResettablePhasesImpl}, - qom::{ObjectImpl, ParentField}, sysbus::SysBusDevice, }; +use qom::{prelude::*, ObjectImpl, ParentField}; use util::bindings::{module_call_init, module_init_type}; mod vmstate_tests; diff --git a/rust/qom/Cargo.toml b/rust/qom/Cargo.toml new file mode 100644 index 0000000000..46bbf7c7fe --- /dev/null +++ b/rust/qom/Cargo.toml @@ -0,0 +1,23 @@ +[package] +name = "qom" +version = "0.1.0" +description = "Rust bindings for QEMU/QOM" +resolver = "2" +publish = false + +authors.workspace = true +edition.workspace = true +homepage.workspace = true +license.workspace = true +repository.workspace = true +rust-version.workspace = true + +[dependencies] +common = { path = "../common" } +bql = { path = "../bql" } +migration = { path = "../migration" } +qemu_api_macros = { path = "../qemu-api-macros" } +util = { path = "../util" } + +[lints] +workspace = true diff --git a/rust/qom/build.rs b/rust/qom/build.rs new file mode 120000 index 0000000000..71a3167885 --- /dev/null +++ b/rust/qom/build.rs @@ -0,0 +1 @@ +../util/build.rs \ No newline at end of file diff --git a/rust/qom/meson.build b/rust/qom/meson.build new file mode 100644 index 0000000000..84a65cb737 --- /dev/null +++ b/rust/qom/meson.build @@ -0,0 +1,43 @@ +# TODO: Remove this comment when the clang/libclang mismatch issue is solved. +# +# Rust bindings generation with `bindgen` might fail in some cases where the +# detected `libclang` does not match the expected `clang` version/target. In +# this case you must pass the path to `clang` and `libclang` to your build +# command invocation using the environment variables CLANG_PATH and +# LIBCLANG_PATH +_qom_bindings_inc_rs = rust.bindgen( + input: 'wrapper.h', + dependencies: common_ss.all_dependencies(), + output: 'bindings.inc.rs', + include_directories: bindings_incdir, + bindgen_version: ['>=0.60.0'], + args: bindgen_args_common, +) + +_qom_rs = static_library( + 'qom', + structured_sources( + [ + 'src/lib.rs', + 'src/bindings.rs', + 'src/prelude.rs', + 'src/qom.rs', + ], + {'.': _qom_bindings_inc_rs} + ), + override_options: ['rust_std=2021', 'build.rust_std=2021'], + rust_abi: 'rust', + link_with: [_bql_rs, _migration_rs], + dependencies: [common_rs, qemu_api_macros], +) + +qom_rs = declare_dependency(link_with: [_qom_rs], dependencies: [qemu_api_macros, qom]) + +# Doctests are essentially integration tests, so they need the same dependencies. +# Note that running them requires the object files for C code, so place them +# in a separate suite that is run by the "build" CI jobs rather than "check". +rust.doctest('rust-qom-rs-doctests', + _qom_rs, + protocol: 'rust', + dependencies: qom_rs, + suite: ['doc', 'rust']) diff --git a/rust/qom/src/bindings.rs b/rust/qom/src/bindings.rs new file mode 100644 index 0000000000..9ffff12cde --- /dev/null +++ b/rust/qom/src/bindings.rs @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#![allow( + dead_code, + improper_ctypes_definitions, + improper_ctypes, + non_camel_case_types, + non_snake_case, + non_upper_case_globals, + unnecessary_transmutes, + unsafe_op_in_unsafe_fn, + clippy::pedantic, + clippy::restriction, + clippy::style, + clippy::missing_const_for_fn, + clippy::ptr_offset_with_cast, + clippy::useless_transmute, + clippy::missing_safety_doc, + clippy::too_many_arguments +)] + +#[cfg(MESON)] +include!("bindings.inc.rs"); + +#[cfg(not(MESON))] +include!(concat!(env!("OUT_DIR"), "/bindings.inc.rs")); diff --git a/rust/qom/src/lib.rs b/rust/qom/src/lib.rs new file mode 100644 index 0000000000..204c6fea2f --- /dev/null +++ b/rust/qom/src/lib.rs @@ -0,0 +1,11 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +pub mod bindings; + +// preserve one-item-per-"use" syntax, it is clearer +// for prelude-like modules +#[rustfmt::skip] +pub mod prelude; + +mod qom; +pub use qom::*; diff --git a/rust/qom/src/prelude.rs b/rust/qom/src/prelude.rs new file mode 100644 index 0000000000..00a6095977 --- /dev/null +++ b/rust/qom/src/prelude.rs @@ -0,0 +1,12 @@ +//! Traits and essential types intended for blanket imports. + +pub use crate::qom::InterfaceType; +pub use crate::qom::IsA; +pub use crate::qom::Object; +pub use crate::qom::ObjectCast; +pub use crate::qom::ObjectClassMethods; +pub use crate::qom::ObjectDeref; +pub use crate::qom::ObjectMethods; +pub use crate::qom::ObjectType; + +pub use crate::qom_isa; diff --git a/rust/qom/src/qom.rs b/rust/qom/src/qom.rs new file mode 100644 index 0000000000..3ea1ad9c5b --- /dev/null +++ b/rust/qom/src/qom.rs @@ -0,0 +1,951 @@ +// Copyright 2024, Linaro Limited +// Author(s): Manos Pitsidianakis +// SPDX-License-Identifier: GPL-2.0-or-later + +//! Bindings to access QOM functionality from Rust. +//! +//! The QEMU Object Model (QOM) provides inheritance and dynamic typing for QEMU +//! devices. This module makes QOM's features available in Rust through three +//! main mechanisms: +//! +//! * Automatic creation and registration of `TypeInfo` for classes that are +//! written in Rust, as well as mapping between Rust traits and QOM vtables. +//! +//! * Type-safe casting between parent and child classes, through the [`IsA`] +//! trait and methods such as [`upcast`](ObjectCast::upcast) and +//! [`downcast`](ObjectCast::downcast). +//! +//! * Automatic delegation of parent class methods to child classes. When a +//! trait uses [`IsA`] as a bound, its contents become available to all child +//! classes through blanket implementations. This works both for class methods +//! and for instance methods accessed through references or smart pointers. +//! +//! # Structure of a class +//! +//! A leaf class only needs a struct holding instance state. The struct must +//! implement the [`ObjectType`] and [`IsA`] traits, as well as any `*Impl` +//! traits that exist for its superclasses. +//! +//! If a class has subclasses, it will also provide a struct for instance data, +//! with the same characteristics as for concrete classes, but it also needs +//! additional components to support virtual methods: +//! +//! * a struct for class data, for example `DeviceClass`. This corresponds to +//! the C "class struct" and holds the vtable that is used by instances of the +//! class and its subclasses. It must start with its parent's class struct. +//! +//! * a trait for virtual method implementations, for example `DeviceImpl`. +//! Child classes implement this trait to provide their own behavior for +//! virtual methods. The trait's methods take `&self` to access instance data. +//! The traits have the appropriate specialization of `IsA<>` as a supertrait, +//! for example `IsA` for `DeviceImpl`. +//! +//! * a trait for instance methods, for example `DeviceMethods`. This trait is +//! automatically implemented for any reference or smart pointer to a device +//! instance. It calls into the vtable provides access across all subclasses +//! to methods defined for the class. +//! +//! * optionally, a trait for class methods, for example `DeviceClassMethods`. +//! This provides access to class-wide functionality that doesn't depend on +//! instance data. Like instance methods, these are automatically inherited by +//! child classes. +//! +//! # Class structures +//! +//! Each QOM class that has virtual methods describes them in a +//! _class struct_. Class structs include a parent field corresponding +//! to the vtable of the parent class, all the way up to [`ObjectClass`]. +//! +//! As mentioned above, virtual methods are defined via traits such as +//! `DeviceImpl`. Class structs do not define any trait but, conventionally, +//! all of them have a `class_init` method to initialize the virtual methods +//! based on the trait and then call the same method on the superclass. +//! +//! ```ignore +//! impl YourSubclassClass +//! { +//! pub fn class_init(&mut self) { +//! ... +//! klass.parent_class::class_init(); +//! } +//! } +//! ``` +//! +//! If a class implements a QOM interface. In that case, the function must +//! contain, for each interface, an extra forwarding call as follows: +//! +//! ```ignore +//! ResettableClass::cast::(self).class_init::(); +//! ``` +//! +//! These `class_init` functions are methods on the class rather than a trait, +//! because the bound on `T` (`DeviceImpl` in this case), will change for every +//! class struct. The functions are pointed to by the +//! [`ObjectImpl::CLASS_INIT`] function pointer. While there is no default +//! implementation, in most cases it will be enough to write it as follows: +//! +//! ```ignore +//! const CLASS_INIT: fn(&mut Self::Class)> = Self::Class::class_init::; +//! ``` +//! +//! This design incurs a small amount of code duplication but, by not using +//! traits, it allows the flexibility of implementing bindings in any crate, +//! without incurring into violations of orphan rules for traits. + +use std::{ + ffi::{c_void, CStr}, + fmt, + marker::PhantomData, + mem::{ManuallyDrop, MaybeUninit}, + ops::{Deref, DerefMut}, + ptr::NonNull, +}; + +use common::Opaque; +use migration::impl_vmstate_pointer; + +use crate::bindings::{ + self, object_class_dynamic_cast, object_dynamic_cast, object_get_class, object_get_typename, + object_new, object_ref, object_unref, TypeInfo, +}; +pub use crate::bindings::{type_register_static, ObjectClass}; + +/// A safe wrapper around [`bindings::Object`]. +#[repr(transparent)] +#[derive(Debug, qemu_api_macros::Wrapper)] +pub struct Object(Opaque); + +unsafe impl Send for Object {} +unsafe impl Sync for Object {} + +/// Marker trait: `Self` can be statically upcasted to `P` (i.e. `P` is a direct +/// or indirect parent of `Self`). +/// +/// # Safety +/// +/// The struct `Self` must be `#[repr(C)]` and must begin, directly or +/// indirectly, with a field of type `P`. This ensures that invalid casts, +/// which rely on `IsA<>` for static checking, are rejected at compile time. +pub unsafe trait IsA: ObjectType {} + +// SAFETY: it is always safe to cast to your own type +unsafe impl IsA for T {} + +/// Macro to mark superclasses of QOM classes. This enables type-safe +/// up- and downcasting. +/// +/// # Safety +/// +/// This macro is a thin wrapper around the [`IsA`] trait and performs +/// no checking whatsoever of what is declared. It is the caller's +/// responsibility to have $struct begin, directly or indirectly, with +/// a field of type `$parent`. +#[macro_export] +macro_rules! qom_isa { + ($struct:ty : $($parent:ty),* ) => { + $( + // SAFETY: it is the caller responsibility to have $parent as the + // first field + unsafe impl $crate::IsA<$parent> for $struct {} + + impl AsRef<$parent> for $struct { + fn as_ref(&self) -> &$parent { + // SAFETY: follows the same rules as for IsA, which is + // declared above. + let ptr: *const Self = self; + unsafe { &*ptr.cast::<$parent>() } + } + } + )* + }; +} + +/// This is the same as [`ManuallyDrop`](std::mem::ManuallyDrop), though +/// it hides the standard methods of `ManuallyDrop`. +/// +/// The first field of an `ObjectType` must be of type `ParentField`. +/// (Technically, this is only necessary if there is at least one Rust +/// superclass in the hierarchy). This is to ensure that the parent field is +/// dropped after the subclass; this drop order is enforced by the C +/// `object_deinit` function. +/// +/// # Examples +/// +/// ```ignore +/// #[repr(C)] +/// #[derive(qemu_api_macros::Object)] +/// pub struct MyDevice { +/// parent: ParentField, +/// ... +/// } +/// ``` +#[derive(Debug)] +#[repr(transparent)] +pub struct ParentField(std::mem::ManuallyDrop); + +impl Deref for ParentField { + type Target = T; + + #[inline(always)] + fn deref(&self) -> &Self::Target { + &self.0 + } +} + +impl DerefMut for ParentField { + #[inline(always)] + fn deref_mut(&mut self) -> &mut Self::Target { + &mut self.0 + } +} + +impl fmt::Display for ParentField { + #[inline(always)] + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> { + self.0.fmt(f) + } +} + +/// This struct knows that the superclasses of the object have already been +/// initialized. +/// +/// The declaration of `ParentInit` is.. *"a kind of magic"*. It uses a +/// technique that is found in several crates, the main ones probably being +/// `ghost-cell` (in fact it was introduced by the [`GhostCell` paper](https://plv.mpi-sws.org/rustbelt/ghostcell/)) +/// and `generativity`. +/// +/// The `PhantomData` makes the `ParentInit` type *invariant* with respect to +/// the lifetime argument `'init`. This, together with the `for<'...>` in +/// `[ParentInit::with]`, block any attempt of the compiler to be creative when +/// operating on types of type `ParentInit` and to extend their lifetimes. In +/// particular, it ensures that the `ParentInit` cannot be made to outlive the +/// `rust_instance_init()` function that creates it, and therefore that the +/// `&'init T` reference is valid. +/// +/// This implementation of the same concept, without the QOM baggage, can help +/// understanding the effect: +/// +/// ``` +/// use std::marker::PhantomData; +/// +/// #[derive(PartialEq, Eq)] +/// pub struct Jail<'closure, T: Copy>(&'closure T, PhantomData &'closure ()>); +/// +/// impl<'closure, T: Copy> Jail<'closure, T> { +/// fn get(&self) -> T { +/// *self.0 +/// } +/// +/// #[inline] +/// fn with(v: T, f: impl for<'id> FnOnce(Jail<'id, T>) -> U) -> U { +/// let parent_init = Jail(&v, PhantomData); +/// f(parent_init) +/// } +/// } +/// ``` +/// +/// It's impossible to escape the `Jail`; `token1` cannot be moved out of the +/// closure: +/// +/// ```ignore +/// let x = 42; +/// let escape = Jail::with(&x, |token1| { +/// println!("{}", token1.get()); +/// // fails to compile... +/// token1 +/// }); +/// // ... so you cannot do this: +/// println!("{}", escape.get()); +/// ``` +/// +/// Likewise, in the QOM case the `ParentInit` cannot be moved out of +/// `instance_init()`. Without this trick it would be possible to stash a +/// `ParentInit` and use it later to access uninitialized memory. +/// +/// Here is another example, showing how separately-created "identities" stay +/// isolated: +/// +/// ```ignore +/// impl<'closure, T: Copy> Clone for Jail<'closure, T> { +/// fn clone(&self) -> Jail<'closure, T> { +/// Jail(self.0, PhantomData) +/// } +/// } +/// +/// fn main() { +/// Jail::with(42, |token1| { +/// // this works and returns true: the clone has the same "identity" +/// println!("{}", token1 == token1.clone()); +/// Jail::with(42, |token2| { +/// // here the outer token remains accessible... +/// println!("{}", token1.get()); +/// // ... but the two are separate: this fails to compile: +/// println!("{}", token1 == token2); +/// }); +/// }); +/// } +/// ``` +pub struct ParentInit<'init, T>( + &'init mut MaybeUninit, + PhantomData &'init ()>, +); + +impl<'init, T> ParentInit<'init, T> { + #[inline] + pub fn with(obj: &'init mut MaybeUninit, f: impl for<'id> FnOnce(ParentInit<'id, T>)) { + let parent_init = ParentInit(obj, PhantomData); + f(parent_init) + } +} + +impl ParentInit<'_, T> { + /// Return the receiver as a mutable raw pointer to Object. + /// + /// # Safety + /// + /// Fields beyond `Object` could be uninitialized and it's your + /// responsibility to avoid that they're used when the pointer is + /// dereferenced, either directly or through a cast. + pub const fn as_object_mut_ptr(&self) -> *mut bindings::Object { + self.as_object_ptr().cast_mut() + } + + /// Return the receiver as a mutable raw pointer to Object. + /// + /// # Safety + /// + /// Fields beyond `Object` could be uninitialized and it's your + /// responsibility to avoid that they're used when the pointer is + /// dereferenced, either directly or through a cast. + pub const fn as_object_ptr(&self) -> *const bindings::Object { + self.0.as_ptr().cast() + } +} + +impl<'a, T: ObjectImpl> ParentInit<'a, T> { + /// Convert from a derived type to one of its parent types, which + /// have already been initialized. + /// + /// # Safety + /// + /// Structurally this is always a safe operation; the [`IsA`] trait + /// provides static verification trait that `Self` dereferences to `U` or + /// a child of `U`, and only parent types of `T` are allowed. + /// + /// However, while the fields of the resulting reference are initialized, + /// calls might use uninitialized fields of the subclass. It is your + /// responsibility to avoid this. + pub const unsafe fn upcast(&self) -> &'a U + where + T::ParentType: IsA, + { + // SAFETY: soundness is declared via IsA, which is an unsafe trait; + // the parent has been initialized before `instance_init `is called + unsafe { &*(self.0.as_ptr().cast::()) } + } + + /// Convert from a derived type to one of its parent types, which + /// have already been initialized. + /// + /// # Safety + /// + /// Structurally this is always a safe operation; the [`IsA`] trait + /// provides static verification trait that `Self` dereferences to `U` or + /// a child of `U`, and only parent types of `T` are allowed. + /// + /// However, while the fields of the resulting reference are initialized, + /// calls might use uninitialized fields of the subclass. It is your + /// responsibility to avoid this. + pub unsafe fn upcast_mut(&mut self) -> &'a mut U + where + T::ParentType: IsA, + { + // SAFETY: soundness is declared via IsA, which is an unsafe trait; + // the parent has been initialized before `instance_init `is called + unsafe { &mut *(self.0.as_mut_ptr().cast::()) } + } +} + +impl Deref for ParentInit<'_, T> { + type Target = MaybeUninit; + + fn deref(&self) -> &Self::Target { + self.0 + } +} + +impl DerefMut for ParentInit<'_, T> { + fn deref_mut(&mut self) -> &mut Self::Target { + self.0 + } +} + +unsafe extern "C" fn rust_instance_init(obj: *mut bindings::Object) { + let mut state = NonNull::new(obj).unwrap().cast::>(); + + // SAFETY: obj is an instance of T, since rust_instance_init + // is called from QOM core as the instance_init function + // for class T + unsafe { + ParentInit::with(state.as_mut(), |parent_init| { + T::INSTANCE_INIT.unwrap()(parent_init); + }); + } +} + +unsafe extern "C" fn rust_instance_post_init(obj: *mut bindings::Object) { + let state = NonNull::new(obj).unwrap().cast::(); + // SAFETY: obj is an instance of T, since rust_instance_post_init + // is called from QOM core as the instance_post_init function + // for class T + T::INSTANCE_POST_INIT.unwrap()(unsafe { state.as_ref() }); +} + +unsafe extern "C" fn rust_class_init( + klass: *mut ObjectClass, + _data: *const c_void, +) { + let mut klass = NonNull::new(klass) + .unwrap() + .cast::<::Class>(); + // SAFETY: klass is a T::Class, since rust_class_init + // is called from QOM core as the class_init function + // for class T + ::CLASS_INIT(unsafe { klass.as_mut() }) +} + +unsafe extern "C" fn drop_object(obj: *mut bindings::Object) { + // SAFETY: obj is an instance of T, since drop_object is called + // from the QOM core function object_deinit() as the instance_finalize + // function for class T. Note that while object_deinit() will drop the + // superclass field separately after this function returns, `T` must + // implement the unsafe trait ObjectType; the safety rules for the + // trait mandate that the parent field is manually dropped. + unsafe { std::ptr::drop_in_place(obj.cast::()) } +} + +/// Trait exposed by all structs corresponding to QOM objects. +/// +/// # Safety +/// +/// For classes declared in C: +/// +/// - `Class` and `TYPE` must match the data in the `TypeInfo`; +/// +/// - the first field of the struct must be of the instance type corresponding +/// to the superclass, as declared in the `TypeInfo` +/// +/// - likewise, the first field of the `Class` struct must be of the class type +/// corresponding to the superclass +/// +/// For classes declared in Rust and implementing [`ObjectImpl`]: +/// +/// - the struct must be `#[repr(C)]`; +/// +/// - the first field of the struct must be of type +/// [`ParentField`](ParentField), where `T` is the parent type +/// [`ObjectImpl::ParentType`] +/// +/// - the first field of the `Class` must be of the class struct corresponding +/// to the superclass, which is `ObjectImpl::ParentType::Class`. `ParentField` +/// is not needed here. +/// +/// In both cases, having a separate class type is not necessary if the subclass +/// does not add any field. +pub unsafe trait ObjectType: Sized { + /// The QOM class object corresponding to this struct. This is used + /// to automatically generate a `class_init` method. + type Class; + + /// The name of the type, which can be passed to `object_new()` to + /// generate an instance of this type. + const TYPE_NAME: &'static CStr; + + /// Return the receiver as an Object. This is always safe, even + /// if this type represents an interface. + fn as_object(&self) -> &Object { + unsafe { &*self.as_ptr().cast() } + } + + /// Return the receiver as a const raw pointer to Object. + /// This is preferable to `as_object_mut_ptr()` if a C + /// function only needs a `const Object *`. + fn as_object_ptr(&self) -> *const bindings::Object { + self.as_object().as_ptr() + } + + /// Return the receiver as a mutable raw pointer to Object. + /// + /// # Safety + /// + /// This cast is always safe, but because the result is mutable + /// and the incoming reference is not, this should only be used + /// for calls to C functions, and only if needed. + unsafe fn as_object_mut_ptr(&self) -> *mut bindings::Object { + self.as_object().as_mut_ptr() + } +} + +/// Trait exposed by all structs corresponding to QOM interfaces. +/// Unlike `ObjectType`, it is implemented on the class type (which provides +/// the vtable for the interfaces). +/// +/// # Safety +/// +/// `TYPE` must match the contents of the `TypeInfo` as found in the C code; +/// right now, interfaces can only be declared in C. +pub unsafe trait InterfaceType: Sized { + /// The name of the type, which can be passed to + /// `object_class_dynamic_cast()` to obtain the pointer to the vtable + /// for this interface. + const TYPE_NAME: &'static CStr; + + /// Return the vtable for the interface; `U` is the type that + /// lists the interface in its `TypeInfo`. + /// + /// # Examples + /// + /// This function is usually called by a `class_init` method in `U::Class`. + /// For example, `DeviceClass::class_init` initializes its `Resettable` + /// interface as follows: + /// + /// ```ignore + /// ResettableClass::cast::(self).class_init::(); + /// ``` + /// + /// where `T` is the concrete subclass that is being initialized. + /// + /// # Panics + /// + /// Panic if the incoming argument if `T` does not implement the interface. + fn cast(klass: &mut U::Class) -> &mut Self { + unsafe { + // SAFETY: upcasting to ObjectClass is always valid, and the + // return type is either NULL or the argument itself + let result: *mut Self = object_class_dynamic_cast( + (klass as *mut U::Class).cast(), + Self::TYPE_NAME.as_ptr(), + ) + .cast(); + result.as_mut().unwrap() + } + } +} + +/// This trait provides safe casting operations for QOM objects to raw pointers, +/// to be used for example for FFI. The trait can be applied to any kind of +/// reference or smart pointers, and enforces correctness through the [`IsA`] +/// trait. +pub trait ObjectDeref: Deref +where + Self::Target: ObjectType, +{ + /// Convert to a const Rust pointer, to be used for example for FFI. + /// The target pointer type must be the type of `self` or a superclass + fn as_ptr(&self) -> *const U + where + Self::Target: IsA, + { + let ptr: *const Self::Target = self.deref(); + ptr.cast::() + } + + /// Convert to a mutable Rust pointer, to be used for example for FFI. + /// The target pointer type must be the type of `self` or a superclass. + /// Used to implement interior mutability for objects. + /// + /// # Safety + /// + /// This method is safe because only the actual dereference of the pointer + /// has to be unsafe. Bindings to C APIs will use it a lot, but care has + /// to be taken because it overrides the const-ness of `&self`. + fn as_mut_ptr(&self) -> *mut U + where + Self::Target: IsA, + { + #[allow(clippy::as_ptr_cast_mut)] + { + self.as_ptr::().cast_mut() + } + } +} + +/// Trait that adds extra functionality for `&T` where `T` is a QOM +/// object type. Allows conversion to/from C objects in generic code. +pub trait ObjectCast: ObjectDeref + Copy +where + Self::Target: ObjectType, +{ + /// Safely convert from a derived type to one of its parent types. + /// + /// This is always safe; the [`IsA`] trait provides static verification + /// trait that `Self` dereferences to `U` or a child of `U`. + fn upcast<'a, U: ObjectType>(self) -> &'a U + where + Self::Target: IsA, + Self: 'a, + { + // SAFETY: soundness is declared via IsA, which is an unsafe trait + unsafe { self.unsafe_cast::() } + } + + /// Attempt to convert to a derived type. + /// + /// Returns `None` if the object is not actually of type `U`. This is + /// verified at runtime by checking the object's type information. + fn downcast<'a, U: IsA>(self) -> Option<&'a U> + where + Self: 'a, + { + self.dynamic_cast::() + } + + /// Attempt to convert between any two types in the QOM hierarchy. + /// + /// Returns `None` if the object is not actually of type `U`. This is + /// verified at runtime by checking the object's type information. + fn dynamic_cast<'a, U: ObjectType>(self) -> Option<&'a U> + where + Self: 'a, + { + unsafe { + // SAFETY: upcasting to Object is always valid, and the + // return type is either NULL or the argument itself + let result: *const U = + object_dynamic_cast(self.as_object_mut_ptr(), U::TYPE_NAME.as_ptr()).cast(); + + result.as_ref() + } + } + + /// Convert to any QOM type without verification. + /// + /// # Safety + /// + /// What safety? You need to know yourself that the cast is correct; only + /// use when performance is paramount. It is still better than a raw + /// pointer `cast()`, which does not even check that you remain in the + /// realm of QOM `ObjectType`s. + /// + /// `unsafe_cast::()` is always safe. + unsafe fn unsafe_cast<'a, U: ObjectType>(self) -> &'a U + where + Self: 'a, + { + unsafe { &*(self.as_ptr::().cast::()) } + } +} + +impl ObjectDeref for &T {} +impl ObjectCast for &T {} + +impl ObjectDeref for &mut T {} + +/// Trait a type must implement to be registered with QEMU. +pub trait ObjectImpl: ObjectType + IsA { + /// The parent of the type. This should match the first field of the + /// struct that implements `ObjectImpl`, minus the `ParentField<_>` wrapper. + type ParentType: ObjectType; + + /// Whether the object can be instantiated + const ABSTRACT: bool = false; + + /// Function that is called to initialize an object. The parent class will + /// have already been initialized so the type is only responsible for + /// initializing its own members. + /// + /// FIXME: The argument is not really a valid reference. `&mut + /// MaybeUninit` would be a better description. + const INSTANCE_INIT: Option)> = None; + + /// Function that is called to finish initialization of an object, once + /// `INSTANCE_INIT` functions have been called. + const INSTANCE_POST_INIT: Option = None; + + /// Called on descendant classes after all parent class initialization + /// has occurred, but before the class itself is initialized. This + /// is only useful if a class is not a leaf, and can be used to undo + /// the effects of copying the contents of the parent's class struct + /// to the descendants. + const CLASS_BASE_INIT: Option< + unsafe extern "C" fn(klass: *mut ObjectClass, data: *const c_void), + > = None; + + const TYPE_INFO: TypeInfo = TypeInfo { + name: Self::TYPE_NAME.as_ptr(), + parent: Self::ParentType::TYPE_NAME.as_ptr(), + instance_size: core::mem::size_of::(), + instance_align: core::mem::align_of::(), + instance_init: match Self::INSTANCE_INIT { + None => None, + Some(_) => Some(rust_instance_init::), + }, + instance_post_init: match Self::INSTANCE_POST_INIT { + None => None, + Some(_) => Some(rust_instance_post_init::), + }, + instance_finalize: Some(drop_object::), + abstract_: Self::ABSTRACT, + class_size: core::mem::size_of::(), + class_init: Some(rust_class_init::), + class_base_init: Self::CLASS_BASE_INIT, + class_data: core::ptr::null(), + interfaces: core::ptr::null(), + }; + + // methods on ObjectClass + const UNPARENT: Option = None; + + /// Store into the argument the virtual method implementations + /// for `Self`. On entry, the virtual method pointers are set to + /// the default values coming from the parent classes; the function + /// can change them to override virtual methods of a parent class. + /// + /// Usually defined simply as `Self::Class::class_init::`; + /// however a default implementation cannot be included here, because the + /// bounds that the `Self::Class::class_init` method places on `Self` are + /// not known in advance. + /// + /// # Safety + /// + /// While `klass`'s parent class is initialized on entry, the other fields + /// are all zero; it is therefore assumed that all fields in `T` can be + /// zeroed, otherwise it would not be possible to provide the class as a + /// `&mut T`. TODO: it may be possible to add an unsafe trait that checks + /// that all fields *after the parent class* (but not the parent class + /// itself) are Zeroable. This unsafe trait can be added via a derive + /// macro. + const CLASS_INIT: fn(&mut Self::Class); +} + +/// # Safety +/// +/// We expect the FFI user of this function to pass a valid pointer that +/// can be downcasted to type `T`. We also expect the device is +/// readable/writeable from one thread at any time. +unsafe extern "C" fn rust_unparent_fn(dev: *mut bindings::Object) { + let state = NonNull::new(dev).unwrap().cast::(); + T::UNPARENT.unwrap()(unsafe { state.as_ref() }); +} + +impl ObjectClass { + /// Fill in the virtual methods of `ObjectClass` based on the definitions in + /// the `ObjectImpl` trait. + pub fn class_init(&mut self) { + if ::UNPARENT.is_some() { + self.unparent = Some(rust_unparent_fn::); + } + } +} + +unsafe impl ObjectType for Object { + type Class = ObjectClass; + const TYPE_NAME: &'static CStr = + unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_OBJECT) }; +} + +/// A reference-counted pointer to a QOM object. +/// +/// `Owned` wraps `T` with automatic reference counting. It increases the +/// reference count when created via [`Owned::from`] or cloned, and decreases +/// it when dropped. This ensures that the reference count remains elevated +/// as long as any `Owned` references to it exist. +/// +/// `Owned` can be used for two reasons: +/// * because the lifetime of the QOM object is unknown and someone else could +/// take a reference (similar to `Arc`, for example): in this case, the +/// object can escape and outlive the Rust struct that contains the `Owned` +/// field; +/// +/// * to ensure that the object stays alive until after `Drop::drop` is called +/// on the Rust struct: in this case, the object will always die together with +/// the Rust struct that contains the `Owned` field. +/// +/// Child properties are an example of the second case: in C, an object that +/// is created with `object_initialize_child` will die *before* +/// `instance_finalize` is called, whereas Rust expects the struct to have valid +/// contents when `Drop::drop` is called. Therefore Rust structs that have +/// child properties need to keep a reference to the child object. Right now +/// this can be done with `Owned`; in the future one might have a separate +/// `Child<'parent, T>` smart pointer that keeps a reference to a `T`, like +/// `Owned`, but does not allow cloning. +/// +/// Note that dropping an `Owned` requires the big QEMU lock to be taken. +#[repr(transparent)] +#[derive(PartialEq, Eq, Hash, PartialOrd, Ord)] +pub struct Owned(NonNull); + +// The following rationale for safety is taken from Linux's kernel::sync::Arc. + +// SAFETY: It is safe to send `Owned` to another thread when the underlying +// `T` is `Sync` because it effectively means sharing `&T` (which is safe +// because `T` is `Sync`); additionally, it needs `T` to be `Send` because any +// thread that has an `Owned` may ultimately access `T` using a +// mutable reference when the reference count reaches zero and `T` is dropped. +unsafe impl Send for Owned {} + +// SAFETY: It is safe to send `&Owned` to another thread when the underlying +// `T` is `Sync` because it effectively means sharing `&T` (which is safe +// because `T` is `Sync`); additionally, it needs `T` to be `Send` because any +// thread that has a `&Owned` may clone it and get an `Owned` on that +// thread, so the thread may ultimately access `T` using a mutable reference +// when the reference count reaches zero and `T` is dropped. +unsafe impl Sync for Owned {} + +impl Owned { + /// Convert a raw C pointer into an owned reference to the QOM + /// object it points to. The object's reference count will be + /// decreased when the `Owned` is dropped. + /// + /// # Panics + /// + /// Panics if `ptr` is NULL. + /// + /// # Safety + /// + /// The caller must indeed own a reference to the QOM object. + /// The object must not be embedded in another unless the outer + /// object is guaranteed to have a longer lifetime. + /// + /// A raw pointer obtained via [`Owned::into_raw()`] can always be passed + /// back to `from_raw()` (assuming the original `Owned` was valid!), + /// since the owned reference remains there between the calls to + /// `into_raw()` and `from_raw()`. + pub unsafe fn from_raw(ptr: *const T) -> Self { + // SAFETY NOTE: while NonNull requires a mutable pointer, only + // Deref is implemented so the pointer passed to from_raw + // remains const + Owned(NonNull::new(ptr.cast_mut()).unwrap()) + } + + /// Obtain a raw C pointer from a reference. `src` is consumed + /// and the reference is leaked. + #[allow(clippy::missing_const_for_fn)] + pub fn into_raw(src: Owned) -> *mut T { + let src = ManuallyDrop::new(src); + src.0.as_ptr() + } + + /// Increase the reference count of a QOM object and return + /// a new owned reference to it. + /// + /// # Safety + /// + /// The object must not be embedded in another, unless the outer + /// object is guaranteed to have a longer lifetime. + pub unsafe fn from(obj: &T) -> Self { + unsafe { + object_ref(obj.as_object_mut_ptr().cast::()); + + // SAFETY NOTE: while NonNull requires a mutable pointer, only + // Deref is implemented so the reference passed to from_raw + // remains shared + Owned(NonNull::new_unchecked(obj.as_mut_ptr())) + } + } +} + +impl Clone for Owned { + fn clone(&self) -> Self { + // SAFETY: creation method is unsafe; whoever calls it has + // responsibility that the pointer is valid, and remains valid + // throughout the lifetime of the `Owned` and its clones. + unsafe { Owned::from(self.deref()) } + } +} + +impl Deref for Owned { + type Target = T; + + fn deref(&self) -> &Self::Target { + // SAFETY: creation method is unsafe; whoever calls it has + // responsibility that the pointer is valid, and remains valid + // throughout the lifetime of the `Owned` and its clones. + // With that guarantee, reference counting ensures that + // the object remains alive. + unsafe { &*self.0.as_ptr() } + } +} +impl ObjectDeref for Owned {} + +impl Drop for Owned { + fn drop(&mut self) { + assert!(bql::is_locked()); + // SAFETY: creation method is unsafe, and whoever calls it has + // responsibility that the pointer is valid, and remains valid + // throughout the lifetime of the `Owned` and its clones. + unsafe { + object_unref(self.as_object_mut_ptr().cast::()); + } + } +} + +impl> fmt::Debug for Owned { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + self.deref().debug_fmt(f) + } +} + +/// Trait for class methods exposed by the Object class. The methods can be +/// called on all objects that have the trait `IsA`. +/// +/// The trait should only be used through the blanket implementation, +/// which guarantees safety via `IsA` +pub trait ObjectClassMethods: IsA { + /// Return a new reference counted instance of this class + fn new() -> Owned { + assert!(bql::is_locked()); + // SAFETY: the object created by object_new is allocated on + // the heap and has a reference count of 1 + unsafe { + let raw_obj = object_new(Self::TYPE_NAME.as_ptr()); + let obj = Object::from_raw(raw_obj).unsafe_cast::(); + Owned::from_raw(obj) + } + } +} + +/// Trait for methods exposed by the Object class. The methods can be +/// called on all objects that have the trait `IsA`. +/// +/// The trait should only be used through the blanket implementation, +/// which guarantees safety via `IsA` +pub trait ObjectMethods: ObjectDeref +where + Self::Target: IsA, +{ + /// Return the name of the type of `self` + fn typename(&self) -> std::borrow::Cow<'_, str> { + let obj = self.upcast::(); + // SAFETY: safety of this is the requirement for implementing IsA + // The result of the C API has static lifetime + unsafe { + let p = object_get_typename(obj.as_mut_ptr()); + CStr::from_ptr(p).to_string_lossy() + } + } + + fn get_class(&self) -> &'static ::Class { + let obj = self.upcast::(); + + // SAFETY: all objects can call object_get_class; the actual class + // type is guaranteed by the implementation of `ObjectType` and + // `ObjectImpl`. + let klass: &'static ::Class = + unsafe { &*object_get_class(obj.as_mut_ptr()).cast() }; + + klass + } + + /// Convenience function for implementing the Debug trait + fn debug_fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_tuple(&self.typename()) + .field(&(self as *const Self)) + .finish() + } +} + +impl ObjectClassMethods for T where T: IsA {} +impl ObjectMethods for R where R::Target: IsA {} + +impl_vmstate_pointer!(Owned where T: VMState + ObjectType); diff --git a/rust/qom/wrapper.h b/rust/qom/wrapper.h new file mode 100644 index 0000000000..3b71bcd3f5 --- /dev/null +++ b/rust/qom/wrapper.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +/* + * This header file is meant to be used as input to the `bindgen` application + * in order to generate C FFI compatible Rust bindings. + */ + +#ifndef __CLANG_STDATOMIC_H +#define __CLANG_STDATOMIC_H +/* + * Fix potential missing stdatomic.h error in case bindgen does not insert the + * correct libclang header paths on its own. We do not use stdatomic.h symbols + * in QEMU code, so it's fine to declare dummy types instead. + */ +typedef enum memory_order { + memory_order_relaxed, + memory_order_consume, + memory_order_acquire, + memory_order_release, + memory_order_acq_rel, + memory_order_seq_cst, +} memory_order; +#endif /* __CLANG_STDATOMIC_H */ + +#include "qemu/osdep.h" + +#include "qom/object.h" -- cgit 1.4.1 From fef932ef09c82c3831ff3336d1b2d566cd6ccae4 Mon Sep 17 00:00:00 2001 From: Marc-André Lureau Date: Mon, 8 Sep 2025 12:49:54 +0200 Subject: rust: split "chardev" crate MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Marc-André Lureau Link: https://lore.kernel.org/r/20250827104147.717203-14-marcandre.lureau@redhat.com Reviewed-by: Zhao Liu Signed-off-by: Paolo Bonzini --- MAINTAINERS | 1 + rust/Cargo.lock | 14 +++ rust/chardev/Cargo.toml | 24 ++++ rust/chardev/build.rs | 1 + rust/chardev/meson.build | 41 ++++++ rust/chardev/src/bindings.rs | 36 ++++++ rust/chardev/src/chardev.rs | 261 +++++++++++++++++++++++++++++++++++++++ rust/chardev/src/lib.rs | 6 + rust/chardev/wrapper.h | 28 +++++ rust/hw/char/pl011/Cargo.toml | 1 + rust/hw/char/pl011/meson.build | 1 + rust/hw/char/pl011/src/device.rs | 2 +- rust/meson.build | 1 + rust/qemu-api/Cargo.toml | 1 + rust/qemu-api/meson.build | 9 +- rust/qemu-api/src/bindings.rs | 9 +- rust/qemu-api/src/chardev.rs | 261 --------------------------------------- rust/qemu-api/src/lib.rs | 1 - rust/qemu-api/src/qdev.rs | 6 +- rust/qemu-api/wrapper.h | 2 - 20 files changed, 425 insertions(+), 281 deletions(-) create mode 100644 rust/chardev/Cargo.toml create mode 120000 rust/chardev/build.rs create mode 100644 rust/chardev/meson.build create mode 100644 rust/chardev/src/bindings.rs create mode 100644 rust/chardev/src/chardev.rs create mode 100644 rust/chardev/src/lib.rs create mode 100644 rust/chardev/wrapper.h delete mode 100644 rust/qemu-api/src/chardev.rs (limited to 'rust/qemu-api/src/chardev.rs') diff --git a/MAINTAINERS b/MAINTAINERS index c7bd02aef1..cac6dcdc65 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3516,6 +3516,7 @@ Rust M: Manos Pitsidianakis S: Maintained F: rust/bql/ +F: rust/chardev/ F: rust/common/ F: rust/migration/ F: rust/qemu-api diff --git a/rust/Cargo.lock b/rust/Cargo.lock index 442eadf08f..ae852c5550 100644 --- a/rust/Cargo.lock +++ b/rust/Cargo.lock @@ -51,6 +51,18 @@ dependencies = [ "migration", ] +[[package]] +name = "chardev" +version = "0.1.0" +dependencies = [ + "bql", + "common", + "migration", + "qemu_api_macros", + "qom", + "util", +] + [[package]] name = "common" version = "0.1.0" @@ -118,6 +130,7 @@ dependencies = [ "bilge-impl", "bits", "bql", + "chardev", "common", "migration", "qemu_api", @@ -163,6 +176,7 @@ name = "qemu_api" version = "0.1.0" dependencies = [ "bql", + "chardev", "common", "migration", "qemu_api_macros", diff --git a/rust/chardev/Cargo.toml b/rust/chardev/Cargo.toml new file mode 100644 index 0000000000..7df9c677fc --- /dev/null +++ b/rust/chardev/Cargo.toml @@ -0,0 +1,24 @@ +[package] +name = "chardev" +version = "0.1.0" +description = "Rust bindings for QEMU/chardev" +resolver = "2" +publish = false + +authors.workspace = true +edition.workspace = true +homepage.workspace = true +license.workspace = true +repository.workspace = true +rust-version.workspace = true + +[dependencies] +common = { path = "../common" } +bql = { path = "../bql" } +migration = { path = "../migration" } +qom = { path = "../qom" } +util = { path = "../util" } +qemu_api_macros = { path = "../qemu-api-macros" } + +[lints] +workspace = true diff --git a/rust/chardev/build.rs b/rust/chardev/build.rs new file mode 120000 index 0000000000..71a3167885 --- /dev/null +++ b/rust/chardev/build.rs @@ -0,0 +1 @@ +../util/build.rs \ No newline at end of file diff --git a/rust/chardev/meson.build b/rust/chardev/meson.build new file mode 100644 index 0000000000..5d333e232b --- /dev/null +++ b/rust/chardev/meson.build @@ -0,0 +1,41 @@ +c_enums = [ + 'QEMUChrEvent', +] +_chardev_bindgen_args = [] +foreach enum : c_enums + _chardev_bindgen_args += ['--rustified-enum', enum] +endforeach + +# TODO: Remove this comment when the clang/libclang mismatch issue is solved. +# +# Rust bindings generation with `bindgen` might fail in some cases where the +# detected `libclang` does not match the expected `clang` version/target. In +# this case you must pass the path to `clang` and `libclang` to your build +# command invocation using the environment variables CLANG_PATH and +# LIBCLANG_PATH +_chardev_bindings_inc_rs = rust.bindgen( + input: 'wrapper.h', + dependencies: common_ss.all_dependencies(), + output: 'bindings.inc.rs', + include_directories: bindings_incdir, + bindgen_version: ['>=0.60.0'], + args: bindgen_args_common + _chardev_bindgen_args, +) + +_chardev_rs = static_library( + 'chardev', + structured_sources( + [ + 'src/lib.rs', + 'src/bindings.rs', + 'src/chardev.rs', + ], + {'.': _chardev_bindings_inc_rs} + ), + override_options: ['rust_std=2021', 'build.rust_std=2021'], + rust_abi: 'rust', + link_with: [_bql_rs, _migration_rs, _qom_rs, _util_rs], + dependencies: [common_rs, qemu_api_macros], +) + +chardev_rs = declare_dependency(link_with: [_chardev_rs], dependencies: [qemu_api_macros, chardev, qemuutil]) diff --git a/rust/chardev/src/bindings.rs b/rust/chardev/src/bindings.rs new file mode 100644 index 0000000000..2d98026d62 --- /dev/null +++ b/rust/chardev/src/bindings.rs @@ -0,0 +1,36 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#![allow( + dead_code, + improper_ctypes_definitions, + improper_ctypes, + non_camel_case_types, + non_snake_case, + non_upper_case_globals, + unnecessary_transmutes, + unsafe_op_in_unsafe_fn, + clippy::pedantic, + clippy::restriction, + clippy::style, + clippy::missing_const_for_fn, + clippy::ptr_offset_with_cast, + clippy::useless_transmute, + clippy::missing_safety_doc, + clippy::too_many_arguments +)] + +use common::Zeroable; + +#[cfg(MESON)] +include!("bindings.inc.rs"); + +#[cfg(not(MESON))] +include!(concat!(env!("OUT_DIR"), "/bindings.inc.rs")); + +// SAFETY: these are implemented in C; the bindings need to assert that the +// BQL is taken, either directly or via `BqlCell` and `BqlRefCell`. +// When bindings for character devices are introduced, this can be +// moved to the Opaque<> wrapper in src/chardev.rs. +unsafe impl Send for CharBackend {} +unsafe impl Sync for CharBackend {} + +unsafe impl Zeroable for CharBackend {} diff --git a/rust/chardev/src/chardev.rs b/rust/chardev/src/chardev.rs new file mode 100644 index 0000000000..072d806e4a --- /dev/null +++ b/rust/chardev/src/chardev.rs @@ -0,0 +1,261 @@ +// Copyright 2024 Red Hat, Inc. +// Author(s): Paolo Bonzini +// SPDX-License-Identifier: GPL-2.0-or-later + +//! Bindings for character devices +//! +//! Character devices in QEMU can run under the big QEMU lock or in a separate +//! `GMainContext`. Here we only support the former, because the bindings +//! enforce that the BQL is taken whenever the functions in [`CharBackend`] are +//! called. + +use std::{ + ffi::{c_int, c_void, CStr}, + fmt::{self, Debug}, + io::{self, ErrorKind, Write}, + marker::PhantomPinned, + ptr::addr_of_mut, + slice, +}; + +use bql::{BqlRefCell, BqlRefMut}; +use common::{callbacks::FnCall, errno, Opaque}; +use qom::prelude::*; + +use crate::bindings; + +/// A safe wrapper around [`bindings::Chardev`]. +#[repr(transparent)] +#[derive(qemu_api_macros::Wrapper)] +pub struct Chardev(Opaque); + +pub type ChardevClass = bindings::ChardevClass; +pub type Event = bindings::QEMUChrEvent; + +/// A safe wrapper around [`bindings::CharBackend`], denoting the character +/// back-end that is used for example by a device. Compared to the +/// underlying C struct it adds BQL protection, and is marked as pinned +/// because the QOM object ([`bindings::Chardev`]) contains a pointer to +/// the `CharBackend`. +pub struct CharBackend { + inner: BqlRefCell, + _pin: PhantomPinned, +} + +pub struct CharBackendMut<'a>(BqlRefMut<'a, bindings::CharBackend>); + +impl Write for CharBackendMut<'_> { + fn flush(&mut self) -> io::Result<()> { + Ok(()) + } + + fn write(&mut self, buf: &[u8]) -> io::Result { + let chr: &mut bindings::CharBackend = &mut self.0; + + let len = buf.len().try_into().unwrap(); + let r = unsafe { bindings::qemu_chr_fe_write(addr_of_mut!(*chr), buf.as_ptr(), len) }; + errno::into_io_result(r).map(|cnt| cnt as usize) + } + + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + let chr: &mut bindings::CharBackend = &mut self.0; + + let len = buf.len().try_into().unwrap(); + let r = unsafe { bindings::qemu_chr_fe_write_all(addr_of_mut!(*chr), buf.as_ptr(), len) }; + errno::into_io_result(r).and_then(|cnt| { + if cnt as usize == buf.len() { + Ok(()) + } else { + Err(ErrorKind::WriteZero.into()) + } + }) + } +} + +impl Debug for CharBackend { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + // SAFETY: accessed just to print the values + let chr = self.inner.as_ptr(); + Debug::fmt(unsafe { &*chr }, f) + } +} + +// FIXME: use something like PinnedDrop from the pinned_init crate +impl Drop for CharBackend { + fn drop(&mut self) { + self.disable_handlers(); + } +} + +impl CharBackend { + /// Enable the front-end's character device handlers, if there is an + /// associated `Chardev`. + pub fn enable_handlers< + 'chardev, + 'owner: 'chardev, + T, + CanReceiveFn: for<'a> FnCall<(&'a T,), u32>, + ReceiveFn: for<'a, 'b> FnCall<(&'a T, &'b [u8])>, + EventFn: for<'a> FnCall<(&'a T, Event)>, + >( + // When "self" is dropped, the handlers are automatically disabled. + // However, this is not necessarily true if the owner is dropped. + // So require the owner to outlive the character device. + &'chardev self, + owner: &'owner T, + _can_receive: CanReceiveFn, + _receive: ReceiveFn, + _event: EventFn, + ) { + unsafe extern "C" fn rust_can_receive_cb FnCall<(&'a T,), u32>>( + opaque: *mut c_void, + ) -> c_int { + // SAFETY: the values are safe according to the contract of + // enable_handlers() and qemu_chr_fe_set_handlers() + let owner: &T = unsafe { &*(opaque.cast::()) }; + let r = F::call((owner,)); + r.try_into().unwrap() + } + + unsafe extern "C" fn rust_receive_cb FnCall<(&'a T, &'b [u8])>>( + opaque: *mut c_void, + buf: *const u8, + size: c_int, + ) { + // SAFETY: the values are safe according to the contract of + // enable_handlers() and qemu_chr_fe_set_handlers() + let owner: &T = unsafe { &*(opaque.cast::()) }; + let buf = unsafe { slice::from_raw_parts(buf, size.try_into().unwrap()) }; + F::call((owner, buf)) + } + + unsafe extern "C" fn rust_event_cb FnCall<(&'a T, Event)>>( + opaque: *mut c_void, + event: Event, + ) { + // SAFETY: the values are safe according to the contract of + // enable_handlers() and qemu_chr_fe_set_handlers() + let owner: &T = unsafe { &*(opaque.cast::()) }; + F::call((owner, event)) + } + + const { assert!(CanReceiveFn::IS_SOME) }; + let receive_cb: Option = + if ReceiveFn::is_some() { + Some(rust_receive_cb::) + } else { + None + }; + let event_cb: Option = if EventFn::is_some() { + Some(rust_event_cb::) + } else { + None + }; + + let mut chr = self.inner.borrow_mut(); + // SAFETY: the borrow promises that the BQL is taken + unsafe { + bindings::qemu_chr_fe_set_handlers( + addr_of_mut!(*chr), + Some(rust_can_receive_cb::), + receive_cb, + event_cb, + None, + (owner as *const T).cast_mut().cast::(), + core::ptr::null_mut(), + true, + ); + } + } + + /// Disable the front-end's character device handlers. + pub fn disable_handlers(&self) { + let mut chr = self.inner.borrow_mut(); + // SAFETY: the borrow promises that the BQL is taken + unsafe { + bindings::qemu_chr_fe_set_handlers( + addr_of_mut!(*chr), + None, + None, + None, + None, + core::ptr::null_mut(), + core::ptr::null_mut(), + true, + ); + } + } + + /// Notify that the frontend is ready to receive data. + pub fn accept_input(&self) { + let mut chr = self.inner.borrow_mut(); + // SAFETY: the borrow promises that the BQL is taken + unsafe { bindings::qemu_chr_fe_accept_input(addr_of_mut!(*chr)) } + } + + /// Temporarily borrow the character device, allowing it to be used + /// as an implementor of `Write`. Note that it is not valid to drop + /// the big QEMU lock while the character device is borrowed, as + /// that might cause C code to write to the character device. + pub fn borrow_mut(&self) -> impl Write + '_ { + CharBackendMut(self.inner.borrow_mut()) + } + + /// Send a continuous stream of zero bits on the line if `enabled` is + /// true, or a short stream if `enabled` is false. + pub fn send_break(&self, long: bool) -> io::Result<()> { + let mut chr = self.inner.borrow_mut(); + let mut duration: c_int = long.into(); + // SAFETY: the borrow promises that the BQL is taken + let r = unsafe { + bindings::qemu_chr_fe_ioctl( + addr_of_mut!(*chr), + bindings::CHR_IOCTL_SERIAL_SET_BREAK as i32, + addr_of_mut!(duration).cast::(), + ) + }; + + errno::into_io_result(r).map(|_| ()) + } + + /// Write data to a character backend from the front end. This function + /// will send data from the front end to the back end. Unlike + /// `write`, this function will block if the back end cannot + /// consume all of the data attempted to be written. + /// + /// Returns the number of bytes consumed (0 if no associated Chardev) or an + /// error. + pub fn write(&self, buf: &[u8]) -> io::Result { + let len = buf.len().try_into().unwrap(); + // SAFETY: qemu_chr_fe_write is thread-safe + let r = unsafe { bindings::qemu_chr_fe_write(self.inner.as_ptr(), buf.as_ptr(), len) }; + errno::into_io_result(r).map(|cnt| cnt as usize) + } + + /// Write data to a character backend from the front end. This function + /// will send data from the front end to the back end. Unlike + /// `write`, this function will block if the back end cannot + /// consume all of the data attempted to be written. + /// + /// Returns the number of bytes consumed (0 if no associated Chardev) or an + /// error. + pub fn write_all(&self, buf: &[u8]) -> io::Result<()> { + let len = buf.len().try_into().unwrap(); + // SAFETY: qemu_chr_fe_write_all is thread-safe + let r = unsafe { bindings::qemu_chr_fe_write_all(self.inner.as_ptr(), buf.as_ptr(), len) }; + errno::into_io_result(r).and_then(|cnt| { + if cnt as usize == buf.len() { + Ok(()) + } else { + Err(ErrorKind::WriteZero.into()) + } + }) + } +} + +unsafe impl ObjectType for Chardev { + type Class = ChardevClass; + const TYPE_NAME: &'static CStr = + unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_CHARDEV) }; +} +qom_isa!(Chardev: Object); diff --git a/rust/chardev/src/lib.rs b/rust/chardev/src/lib.rs new file mode 100644 index 0000000000..2e549f99d9 --- /dev/null +++ b/rust/chardev/src/lib.rs @@ -0,0 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +pub mod bindings; + +mod chardev; +pub use chardev::*; diff --git a/rust/chardev/wrapper.h b/rust/chardev/wrapper.h new file mode 100644 index 0000000000..65ede6ea6d --- /dev/null +++ b/rust/chardev/wrapper.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +/* + * This header file is meant to be used as input to the `bindgen` application + * in order to generate C FFI compatible Rust bindings. + */ + +#ifndef __CLANG_STDATOMIC_H +#define __CLANG_STDATOMIC_H +/* + * Fix potential missing stdatomic.h error in case bindgen does not insert the + * correct libclang header paths on its own. We do not use stdatomic.h symbols + * in QEMU code, so it's fine to declare dummy types instead. + */ +typedef enum memory_order { + memory_order_relaxed, + memory_order_consume, + memory_order_acquire, + memory_order_release, + memory_order_acq_rel, + memory_order_seq_cst, +} memory_order; +#endif /* __CLANG_STDATOMIC_H */ + +#include "qemu/osdep.h" + +#include "chardev/char-fe.h" +#include "chardev/char-serial.h" diff --git a/rust/hw/char/pl011/Cargo.toml b/rust/hw/char/pl011/Cargo.toml index da89f78727..f7ad5f8e08 100644 --- a/rust/hw/char/pl011/Cargo.toml +++ b/rust/hw/char/pl011/Cargo.toml @@ -21,6 +21,7 @@ util = { path = "../../../util" } bql = { path = "../../../bql" } migration = { path = "../../../migration" } qom = { path = "../../../qom" } +chardev = { path = "../../../chardev" } qemu_api = { path = "../../../qemu-api" } qemu_api_macros = { path = "../../../qemu-api-macros" } diff --git a/rust/hw/char/pl011/meson.build b/rust/hw/char/pl011/meson.build index af9393c9da..aaf911c5f4 100644 --- a/rust/hw/char/pl011/meson.build +++ b/rust/hw/char/pl011/meson.build @@ -14,6 +14,7 @@ _libpl011_rs = static_library( bql_rs, qemu_api_macros, qom_rs, + chardev_rs, ], ) diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs index 63651b9dcd..bc64061fb3 100644 --- a/rust/hw/char/pl011/src/device.rs +++ b/rust/hw/char/pl011/src/device.rs @@ -5,13 +5,13 @@ use std::{ffi::CStr, mem::size_of}; use bql::BqlRefCell; +use chardev::{CharBackend, Chardev, Event}; use common::{static_assert, uninit_field_mut}; use migration::{ self, impl_vmstate_forward, impl_vmstate_struct, vmstate_fields, vmstate_of, vmstate_subsections, vmstate_unused, VMStateDescription, VMStateDescriptionBuilder, }; use qemu_api::{ - chardev::{CharBackend, Chardev, Event}, irq::{IRQState, InterruptSource}, memory::{hwaddr, MemoryRegion, MemoryRegionOps, MemoryRegionOpsBuilder}, prelude::*, diff --git a/rust/meson.build b/rust/meson.build index 043603d416..4d9e291223 100644 --- a/rust/meson.build +++ b/rust/meson.build @@ -29,6 +29,7 @@ subdir('util') subdir('migration') subdir('bql') subdir('qom') +subdir('chardev') subdir('qemu-api') subdir('hw') diff --git a/rust/qemu-api/Cargo.toml b/rust/qemu-api/Cargo.toml index 9d11becb28..3bf2dafa6d 100644 --- a/rust/qemu-api/Cargo.toml +++ b/rust/qemu-api/Cargo.toml @@ -15,6 +15,7 @@ rust-version.workspace = true [dependencies] common = { path = "../common" } +chardev = { path = "../chardev" } migration = { path = "../migration" } util = { path = "../util" } bql = { path = "../bql" } diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index 11e43bb646..a47f178b69 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -7,7 +7,6 @@ c_enums = [ 'GpioPolarity', 'MachineInitPhase', 'MemoryDeviceInfoKind', - 'QEMUChrEvent', 'ResetType', 'device_endian', ] @@ -23,9 +22,10 @@ foreach enum : c_bitfields endforeach blocked_type = [ + 'Chardev', + 'Error', 'ObjectClass', 'VMStateDescription', - 'Error', ] foreach type: blocked_type _qemu_api_bindgen_args += ['--blocklist-type', type] @@ -53,7 +53,6 @@ _qemu_api_rs = static_library( [ 'src/lib.rs', 'src/bindings.rs', - 'src/chardev.rs', 'src/irq.rs', 'src/memory.rs', 'src/prelude.rs', @@ -65,8 +64,8 @@ _qemu_api_rs = static_library( override_options: ['rust_std=2021', 'build.rust_std=2021'], rust_abi: 'rust', rust_args: _qemu_api_cfg, - dependencies: [anyhow_rs, bql_rs, common_rs, foreign_rs, libc_rs, migration_rs, qemu_api_macros, - qom_rs, util_rs, hwcore, chardev], + dependencies: [anyhow_rs, bql_rs, chardev_rs, common_rs, foreign_rs, libc_rs, migration_rs, qemu_api_macros, + qom_rs, util_rs, hwcore], ) qemu_api_rs = declare_dependency(link_with: [_qemu_api_rs], diff --git a/rust/qemu-api/src/bindings.rs b/rust/qemu-api/src/bindings.rs index 525f136ae2..526bcf8e31 100644 --- a/rust/qemu-api/src/bindings.rs +++ b/rust/qemu-api/src/bindings.rs @@ -20,6 +20,7 @@ //! `bindgen`-generated declarations. +use chardev::bindings::Chardev; use common::Zeroable; use migration::bindings::VMStateDescription; use qom::bindings::ObjectClass; @@ -31,13 +32,6 @@ include!("bindings.inc.rs"); #[cfg(not(MESON))] include!(concat!(env!("OUT_DIR"), "/bindings.inc.rs")); -// SAFETY: these are implemented in C; the bindings need to assert that the -// BQL is taken, either directly or via `BqlCell` and `BqlRefCell`. -// When bindings for character devices are introduced, this can be -// moved to the Opaque<> wrapper in src/chardev.rs. -unsafe impl Send for CharBackend {} -unsafe impl Sync for CharBackend {} - // SAFETY: this is a pure data struct unsafe impl Send for CoalescedMemoryRange {} unsafe impl Sync for CoalescedMemoryRange {} @@ -59,4 +53,3 @@ unsafe impl Zeroable for crate::bindings::MemoryRegionOps__bindgen_ty_1 {} unsafe impl Zeroable for crate::bindings::MemoryRegionOps__bindgen_ty_2 {} unsafe impl Zeroable for crate::bindings::MemoryRegionOps {} unsafe impl Zeroable for crate::bindings::MemTxAttrs {} -unsafe impl Zeroable for crate::bindings::CharBackend {} diff --git a/rust/qemu-api/src/chardev.rs b/rust/qemu-api/src/chardev.rs deleted file mode 100644 index 072d806e4a..0000000000 --- a/rust/qemu-api/src/chardev.rs +++ /dev/null @@ -1,261 +0,0 @@ -// Copyright 2024 Red Hat, Inc. -// Author(s): Paolo Bonzini -// SPDX-License-Identifier: GPL-2.0-or-later - -//! Bindings for character devices -//! -//! Character devices in QEMU can run under the big QEMU lock or in a separate -//! `GMainContext`. Here we only support the former, because the bindings -//! enforce that the BQL is taken whenever the functions in [`CharBackend`] are -//! called. - -use std::{ - ffi::{c_int, c_void, CStr}, - fmt::{self, Debug}, - io::{self, ErrorKind, Write}, - marker::PhantomPinned, - ptr::addr_of_mut, - slice, -}; - -use bql::{BqlRefCell, BqlRefMut}; -use common::{callbacks::FnCall, errno, Opaque}; -use qom::prelude::*; - -use crate::bindings; - -/// A safe wrapper around [`bindings::Chardev`]. -#[repr(transparent)] -#[derive(qemu_api_macros::Wrapper)] -pub struct Chardev(Opaque); - -pub type ChardevClass = bindings::ChardevClass; -pub type Event = bindings::QEMUChrEvent; - -/// A safe wrapper around [`bindings::CharBackend`], denoting the character -/// back-end that is used for example by a device. Compared to the -/// underlying C struct it adds BQL protection, and is marked as pinned -/// because the QOM object ([`bindings::Chardev`]) contains a pointer to -/// the `CharBackend`. -pub struct CharBackend { - inner: BqlRefCell, - _pin: PhantomPinned, -} - -pub struct CharBackendMut<'a>(BqlRefMut<'a, bindings::CharBackend>); - -impl Write for CharBackendMut<'_> { - fn flush(&mut self) -> io::Result<()> { - Ok(()) - } - - fn write(&mut self, buf: &[u8]) -> io::Result { - let chr: &mut bindings::CharBackend = &mut self.0; - - let len = buf.len().try_into().unwrap(); - let r = unsafe { bindings::qemu_chr_fe_write(addr_of_mut!(*chr), buf.as_ptr(), len) }; - errno::into_io_result(r).map(|cnt| cnt as usize) - } - - fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { - let chr: &mut bindings::CharBackend = &mut self.0; - - let len = buf.len().try_into().unwrap(); - let r = unsafe { bindings::qemu_chr_fe_write_all(addr_of_mut!(*chr), buf.as_ptr(), len) }; - errno::into_io_result(r).and_then(|cnt| { - if cnt as usize == buf.len() { - Ok(()) - } else { - Err(ErrorKind::WriteZero.into()) - } - }) - } -} - -impl Debug for CharBackend { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - // SAFETY: accessed just to print the values - let chr = self.inner.as_ptr(); - Debug::fmt(unsafe { &*chr }, f) - } -} - -// FIXME: use something like PinnedDrop from the pinned_init crate -impl Drop for CharBackend { - fn drop(&mut self) { - self.disable_handlers(); - } -} - -impl CharBackend { - /// Enable the front-end's character device handlers, if there is an - /// associated `Chardev`. - pub fn enable_handlers< - 'chardev, - 'owner: 'chardev, - T, - CanReceiveFn: for<'a> FnCall<(&'a T,), u32>, - ReceiveFn: for<'a, 'b> FnCall<(&'a T, &'b [u8])>, - EventFn: for<'a> FnCall<(&'a T, Event)>, - >( - // When "self" is dropped, the handlers are automatically disabled. - // However, this is not necessarily true if the owner is dropped. - // So require the owner to outlive the character device. - &'chardev self, - owner: &'owner T, - _can_receive: CanReceiveFn, - _receive: ReceiveFn, - _event: EventFn, - ) { - unsafe extern "C" fn rust_can_receive_cb FnCall<(&'a T,), u32>>( - opaque: *mut c_void, - ) -> c_int { - // SAFETY: the values are safe according to the contract of - // enable_handlers() and qemu_chr_fe_set_handlers() - let owner: &T = unsafe { &*(opaque.cast::()) }; - let r = F::call((owner,)); - r.try_into().unwrap() - } - - unsafe extern "C" fn rust_receive_cb FnCall<(&'a T, &'b [u8])>>( - opaque: *mut c_void, - buf: *const u8, - size: c_int, - ) { - // SAFETY: the values are safe according to the contract of - // enable_handlers() and qemu_chr_fe_set_handlers() - let owner: &T = unsafe { &*(opaque.cast::()) }; - let buf = unsafe { slice::from_raw_parts(buf, size.try_into().unwrap()) }; - F::call((owner, buf)) - } - - unsafe extern "C" fn rust_event_cb FnCall<(&'a T, Event)>>( - opaque: *mut c_void, - event: Event, - ) { - // SAFETY: the values are safe according to the contract of - // enable_handlers() and qemu_chr_fe_set_handlers() - let owner: &T = unsafe { &*(opaque.cast::()) }; - F::call((owner, event)) - } - - const { assert!(CanReceiveFn::IS_SOME) }; - let receive_cb: Option = - if ReceiveFn::is_some() { - Some(rust_receive_cb::) - } else { - None - }; - let event_cb: Option = if EventFn::is_some() { - Some(rust_event_cb::) - } else { - None - }; - - let mut chr = self.inner.borrow_mut(); - // SAFETY: the borrow promises that the BQL is taken - unsafe { - bindings::qemu_chr_fe_set_handlers( - addr_of_mut!(*chr), - Some(rust_can_receive_cb::), - receive_cb, - event_cb, - None, - (owner as *const T).cast_mut().cast::(), - core::ptr::null_mut(), - true, - ); - } - } - - /// Disable the front-end's character device handlers. - pub fn disable_handlers(&self) { - let mut chr = self.inner.borrow_mut(); - // SAFETY: the borrow promises that the BQL is taken - unsafe { - bindings::qemu_chr_fe_set_handlers( - addr_of_mut!(*chr), - None, - None, - None, - None, - core::ptr::null_mut(), - core::ptr::null_mut(), - true, - ); - } - } - - /// Notify that the frontend is ready to receive data. - pub fn accept_input(&self) { - let mut chr = self.inner.borrow_mut(); - // SAFETY: the borrow promises that the BQL is taken - unsafe { bindings::qemu_chr_fe_accept_input(addr_of_mut!(*chr)) } - } - - /// Temporarily borrow the character device, allowing it to be used - /// as an implementor of `Write`. Note that it is not valid to drop - /// the big QEMU lock while the character device is borrowed, as - /// that might cause C code to write to the character device. - pub fn borrow_mut(&self) -> impl Write + '_ { - CharBackendMut(self.inner.borrow_mut()) - } - - /// Send a continuous stream of zero bits on the line if `enabled` is - /// true, or a short stream if `enabled` is false. - pub fn send_break(&self, long: bool) -> io::Result<()> { - let mut chr = self.inner.borrow_mut(); - let mut duration: c_int = long.into(); - // SAFETY: the borrow promises that the BQL is taken - let r = unsafe { - bindings::qemu_chr_fe_ioctl( - addr_of_mut!(*chr), - bindings::CHR_IOCTL_SERIAL_SET_BREAK as i32, - addr_of_mut!(duration).cast::(), - ) - }; - - errno::into_io_result(r).map(|_| ()) - } - - /// Write data to a character backend from the front end. This function - /// will send data from the front end to the back end. Unlike - /// `write`, this function will block if the back end cannot - /// consume all of the data attempted to be written. - /// - /// Returns the number of bytes consumed (0 if no associated Chardev) or an - /// error. - pub fn write(&self, buf: &[u8]) -> io::Result { - let len = buf.len().try_into().unwrap(); - // SAFETY: qemu_chr_fe_write is thread-safe - let r = unsafe { bindings::qemu_chr_fe_write(self.inner.as_ptr(), buf.as_ptr(), len) }; - errno::into_io_result(r).map(|cnt| cnt as usize) - } - - /// Write data to a character backend from the front end. This function - /// will send data from the front end to the back end. Unlike - /// `write`, this function will block if the back end cannot - /// consume all of the data attempted to be written. - /// - /// Returns the number of bytes consumed (0 if no associated Chardev) or an - /// error. - pub fn write_all(&self, buf: &[u8]) -> io::Result<()> { - let len = buf.len().try_into().unwrap(); - // SAFETY: qemu_chr_fe_write_all is thread-safe - let r = unsafe { bindings::qemu_chr_fe_write_all(self.inner.as_ptr(), buf.as_ptr(), len) }; - errno::into_io_result(r).and_then(|cnt| { - if cnt as usize == buf.len() { - Ok(()) - } else { - Err(ErrorKind::WriteZero.into()) - } - }) - } -} - -unsafe impl ObjectType for Chardev { - type Class = ChardevClass; - const TYPE_NAME: &'static CStr = - unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_CHARDEV) }; -} -qom_isa!(Chardev: Object); diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs index 0541050e66..d96096899d 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -13,7 +13,6 @@ pub mod bindings; #[rustfmt::skip] pub mod prelude; -pub mod chardev; pub mod irq; pub mod memory; pub mod qdev; diff --git a/rust/qemu-api/src/qdev.rs b/rust/qemu-api/src/qdev.rs index 3daf9dda2b..7efc796f50 100644 --- a/rust/qemu-api/src/qdev.rs +++ b/rust/qemu-api/src/qdev.rs @@ -10,6 +10,7 @@ use std::{ }; pub use bindings::{ClockEvent, DeviceClass, Property, ResetType}; +use chardev::Chardev; use common::{callbacks::FnCall, Opaque}; use migration::{impl_vmstate_c_struct, VMStateDescription}; use qom::{prelude::*, ObjectClass, ObjectImpl, Owned, ParentInit}; @@ -17,7 +18,6 @@ use util::{Error, Result}; use crate::{ bindings::{self, qdev_init_gpio_in, qdev_init_gpio_out, ResettableClass}, - chardev::Chardev, irq::InterruptSource, }; @@ -137,8 +137,8 @@ unsafe impl QDevProp for u64 { const VALUE: *const bindings::PropertyInfo = unsafe { &bindings::qdev_prop_uint64 }; } -/// Use [`bindings::qdev_prop_chr`] for [`crate::chardev::CharBackend`]. -unsafe impl QDevProp for crate::chardev::CharBackend { +/// Use [`bindings::qdev_prop_chr`] for [`chardev::CharBackend`]. +unsafe impl QDevProp for chardev::CharBackend { const VALUE: *const bindings::PropertyInfo = unsafe { &bindings::qdev_prop_chr }; } diff --git a/rust/qemu-api/wrapper.h b/rust/qemu-api/wrapper.h index b99df9f568..07dbc9987a 100644 --- a/rust/qemu-api/wrapper.h +++ b/rust/qemu-api/wrapper.h @@ -52,13 +52,11 @@ typedef enum memory_order { #include "system/system.h" #include "hw/sysbus.h" #include "system/memory.h" -#include "chardev/char-fe.h" #include "hw/clock.h" #include "hw/qdev-clock.h" #include "hw/qdev-properties.h" #include "hw/qdev-properties-system.h" #include "hw/irq.h" -#include "chardev/char-serial.h" #include "exec/memattrs.h" #include "system/address-spaces.h" #include "hw/char/pl011.h" -- cgit 1.4.1