From cb7ada5409f171dae364f206a7fe3ff30fcba7cb Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Tue, 12 Nov 2024 11:52:23 +0100 Subject: rust: allow using build-root bindings.rs from cargo Right now, using cargo with QEMU requires copying by hand the bindings.rs to the source tree. Instead, we can use an include file to escape the cage of cargo's mandated source directory structure. By running cargo within meson's "devenv" and adding a MESON_BUILD_ROOT environment variable, it is easy for build.rs to find the file. However, the file must be symlinked into cargo's output directory for rust-analyzer to find it. Suggested-by: Junjie Mao Signed-off-by: Paolo Bonzini --- rust/qemu-api/src/lib.rs | 22 ---------------------- 1 file changed, 22 deletions(-) (limited to 'rust/qemu-api/src/lib.rs') diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs index aa8d16ec94..440aff3817 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -4,31 +4,9 @@ #![cfg_attr(not(MESON), doc = include_str!("../README.md"))] -#[allow( - dead_code, - improper_ctypes_definitions, - improper_ctypes, - non_camel_case_types, - non_snake_case, - non_upper_case_globals, - unsafe_op_in_unsafe_fn, - clippy::missing_const_for_fn, - clippy::too_many_arguments, - clippy::approx_constant, - clippy::use_self, - clippy::useless_transmute, - clippy::missing_safety_doc, -)] #[rustfmt::skip] pub mod bindings; -unsafe impl Send for bindings::Property {} -unsafe impl Sync for bindings::Property {} -unsafe impl Sync for bindings::TypeInfo {} -unsafe impl Sync for bindings::VMStateDescription {} -unsafe impl Sync for bindings::VMStateField {} -unsafe impl Sync for bindings::VMStateInfo {} - pub mod c_str; pub mod definitions; pub mod device_class; -- cgit 1.4.1 From 8e194c0ea5cdbae05b77125a582f9927678121ee Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 15 Nov 2024 13:26:58 +0100 Subject: rust: cell: add BQL-enforcing Cell variant QEMU objects usually have their pointer shared with the "outside world" very early in their lifetime, for example when they create their MemoryRegions. Because at this point it is not valid anymore to create a &mut reference to the device, individual parts of the device struct must be made mutable in a controlled manner. QEMU's Big Lock (BQL) effectively turns multi-threaded code into single-threaded code while device code runs, as long as the BQL is not released while the device is borrowed (because C code could sneak in and mutate the device). We can then introduce custom interior mutability primitives that are semantically similar to the standard library's (single-threaded) Cell and RefCell, but account for QEMU's threading model. Accessing the "BqlCell" or borrowing the "BqlRefCell" requires proving that the BQL is held, and attempting to access without the BQL is a runtime panic, similar to RefCell's already-borrowed panic. With respect to naming I also considered omitting the "Bql" prefix or moving it to the module, e.g. qemu_api::bql::{Cell, RefCell}. However, this could easily lead to mistakes and confusion; for example rustc could suggest the wrong import, leading to subtle bugs. As a start introduce the an equivalent of Cell. Almost all of the code was taken from Rust's standard library, while removing unstable features and probably-unnecessary functionality that constitute a large of the original code. A lot of what's left is documentation, as well as unit tests in the form of doctests. These are not yet integrated in "make check" but can be run with "cargo test --doc". Signed-off-by: Paolo Bonzini --- rust/qemu-api/meson.build | 1 + rust/qemu-api/src/cell.rs | 298 ++++++++++++++++++++++++++++++++++++++++++++++ rust/qemu-api/src/lib.rs | 1 + 3 files changed, 300 insertions(+) create mode 100644 rust/qemu-api/src/cell.rs (limited to 'rust/qemu-api/src/lib.rs') diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index d719c13f46..edc21e1a3f 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -13,6 +13,7 @@ _qemu_api_rs = static_library( [ 'src/lib.rs', 'src/bindings.rs', + 'src/cell.rs', 'src/c_str.rs', 'src/definitions.rs', 'src/device_class.rs', diff --git a/rust/qemu-api/src/cell.rs b/rust/qemu-api/src/cell.rs new file mode 100644 index 0000000000..2e4ea8d590 --- /dev/null +++ b/rust/qemu-api/src/cell.rs @@ -0,0 +1,298 @@ +// 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. + +//! BQL-protected 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 through the +//! use of cell types. +//! +//! This module provides a way to do so via the Big QEMU Lock. While +//! [`BqlCell`] is essentially the same single-threaded primitive that is +//! available in `std::cell`, the BQL allows it to be used from a multi-threaded +//! context and to share references across threads, while maintaining Rust's +//! safety guarantees. For this reason, unlike its `std::cell` counterpart, +//! `BqlCell` implements 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. +//! +//! Warning: While `BqlCell` is similar to its `std::cell` counterpart, the two +//! are not interchangeable. Using `std::cell` types in QEMU device +//! implementations is usually incorrect and can lead to thread-safety issues. +//! +//! ## `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. + +use std::{cell::UnsafeCell, cmp::Ordering, fmt, mem}; + +use crate::bindings; + +// TODO: When building doctests do not include the actual BQL, because cargo +// does not know how to link them to libqemuutil. This can be fixed by +// running rustdoc from "meson test" instead of relying on cargo. +pub fn bql_locked() -> bool { + // SAFETY: the function does nothing but return a thread-local bool + !cfg!(MESON) || unsafe { bindings::bql_locked() } +} + +/// 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; + /// + /// 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; + /// + /// 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; + /// + /// 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; + /// + /// 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; + /// + /// 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; + /// + /// 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; + /// + /// 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()) + } +} diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs index 440aff3817..b04d110b3f 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -8,6 +8,7 @@ pub mod bindings; pub mod c_str; +pub mod cell; pub mod definitions; pub mod device_class; pub mod offset_of; -- cgit 1.4.1 From 28d0ad3d425a956a1257256c46ef44581f6678c5 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 5 Dec 2024 13:42:33 +0100 Subject: rust: define prelude Add a module that will contain frequently used traits and occasionally structs. They can be included quickly with "use qemu_api::prelude::*". Signed-off-by: Paolo Bonzini --- rust/qemu-api/meson.build | 1 + rust/qemu-api/src/lib.rs | 5 +++++ rust/qemu-api/src/prelude.rs | 6 ++++++ 3 files changed, 12 insertions(+) create mode 100644 rust/qemu-api/src/prelude.rs (limited to 'rust/qemu-api/src/lib.rs') diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index cacb112c5c..f8b4cd39a2 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -21,6 +21,7 @@ _qemu_api_rs = static_library( 'src/definitions.rs', 'src/device_class.rs', 'src/offset_of.rs', + 'src/prelude.rs', 'src/vmstate.rs', 'src/zeroable.rs', ], diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs index b04d110b3f..e5956cd5eb 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -7,6 +7,11 @@ #[rustfmt::skip] pub mod bindings; +// preserve one-item-per-"use" syntax, it is clearer +// for prelude-like modules +#[rustfmt::skip] +pub mod prelude; + pub mod c_str; pub mod cell; pub mod definitions; diff --git a/rust/qemu-api/src/prelude.rs b/rust/qemu-api/src/prelude.rs new file mode 100644 index 0000000000..dfaddbd062 --- /dev/null +++ b/rust/qemu-api/src/prelude.rs @@ -0,0 +1,6 @@ +// Copyright 2024 Red Hat, Inc. +// Author(s): Paolo Bonzini +// SPDX-License-Identifier: GPL-2.0-or-later + +pub use crate::cell::BqlCell; +pub use crate::cell::BqlRefCell; -- cgit 1.4.1 From 4ed4da164c957a4475b9d075206f33113a69abda Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 31 Oct 2024 11:29:42 +0100 Subject: rust: add bindings for interrupt sources The InterruptSource bindings let us call qemu_set_irq() and sysbus_init_irq() as safe code. Interrupt sources, qemu_irq in C code, are pointers to IRQState objects. They are QOM link properties and can be written to outside the control of the device (i.e. from a shared reference); therefore they must be interior-mutable in Rust. Since thread-safety is provided by the BQL, what we want here is the newly-introduced BqlCell. A pointer to the contents of the BqlCell (an IRQState**, or equivalently qemu_irq*) is then passed to the C sysbus_init_irq function. Signed-off-by: Paolo Bonzini --- rust/hw/char/pl011/src/device.rs | 22 +++++----- rust/qemu-api/meson.build | 2 + rust/qemu-api/src/irq.rs | 91 ++++++++++++++++++++++++++++++++++++++++ rust/qemu-api/src/lib.rs | 2 + rust/qemu-api/src/sysbus.rs | 27 ++++++++++++ 5 files changed, 134 insertions(+), 10 deletions(-) create mode 100644 rust/qemu-api/src/irq.rs create mode 100644 rust/qemu-api/src/sysbus.rs (limited to 'rust/qemu-api/src/lib.rs') diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs index 317a9b3c5a..c5c8c463d3 100644 --- a/rust/hw/char/pl011/src/device.rs +++ b/rust/hw/char/pl011/src/device.rs @@ -13,6 +13,7 @@ use qemu_api::{ c_str, definitions::ObjectImpl, device_class::TYPE_SYS_BUS_DEVICE, + irq::InterruptSource, }; use crate::{ @@ -94,7 +95,7 @@ pub struct PL011State { /// * sysbus IRQ 5: `UARTEINTR` (error interrupt line) /// ``` #[doc(alias = "irq")] - pub interrupts: [qemu_irq; 6usize], + pub interrupts: [InterruptSource; IRQMASK.len()], #[doc(alias = "clk")] pub clock: NonNull, #[doc(alias = "migrate_clk")] @@ -139,7 +140,8 @@ impl PL011State { unsafe fn init(&mut self) { const CLK_NAME: &CStr = c_str!("clk"); - let dev = addr_of_mut!(*self).cast::(); + let sbd = unsafe { &mut *(addr_of_mut!(*self).cast::()) }; + // SAFETY: // // self and self.iomem are guaranteed to be valid at this point since callers @@ -153,12 +155,15 @@ impl PL011State { Self::TYPE_INFO.name, 0x1000, ); - let sbd = addr_of_mut!(*self).cast::(); sysbus_init_mmio(sbd, addr_of_mut!(self.iomem)); - for irq in self.interrupts.iter_mut() { - sysbus_init_irq(sbd, irq); - } } + + for irq in self.interrupts.iter() { + sbd.init_irq(irq); + } + + let dev = addr_of_mut!(*self).cast::(); + // SAFETY: // // self.clock is not initialized at this point; but since `NonNull<_>` is Copy, @@ -498,10 +503,7 @@ impl PL011State { pub fn update(&self) { let flags = self.int_level & self.int_enabled; for (irq, i) in self.interrupts.iter().zip(IRQMASK) { - // SAFETY: self.interrupts have been initialized in init(). - unsafe { - qemu_set_irq(*irq, i32::from(flags & i != 0)); - } + irq.set(flags & i != 0); } } diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index f8b4cd39a2..b927eb58c8 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -20,8 +20,10 @@ _qemu_api_rs = static_library( 'src/c_str.rs', 'src/definitions.rs', 'src/device_class.rs', + 'src/irq.rs', 'src/offset_of.rs', 'src/prelude.rs', + 'src/sysbus.rs', 'src/vmstate.rs', 'src/zeroable.rs', ], diff --git a/rust/qemu-api/src/irq.rs b/rust/qemu-api/src/irq.rs new file mode 100644 index 0000000000..6258141bdf --- /dev/null +++ b/rust/qemu-api/src/irq.rs @@ -0,0 +1,91 @@ +// Copyright 2024 Red Hat, Inc. +// Author(s): Paolo Bonzini +// SPDX-License-Identifier: GPL-2.0-or-later + +//! Bindings for interrupt sources + +use core::ptr; +use std::{marker::PhantomData, os::raw::c_int}; + +use crate::{ + bindings::{qemu_set_irq, IRQState}, + prelude::*, +}; + +/// Interrupt sources are used by devices to pass changes to a value (typically +/// a boolean). The interrupt sink is usually an interrupt controller or +/// GPIO controller. +/// +/// As far as devices are concerned, interrupt sources are always active-high: +/// for example, `InterruptSource`'s [`raise`](InterruptSource::raise) +/// method sends a `true` value to the sink. If the guest has to see a +/// different polarity, that change is performed by the board between the +/// device and the interrupt controller. +/// +/// 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 +/// [`SysBusDevice::init_irq`](crate::sysbus::SysBusDevice::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 +/// devices are generally shared objects, interrupt sources are an example of +/// the interior mutability pattern. +/// +/// Interrupt sources can only be triggered under the Big QEMU Lock; `BqlCell` +/// allows access from whatever thread has it. +#[derive(Debug)] +#[repr(transparent)] +pub struct InterruptSource +where + c_int: From, +{ + cell: BqlCell<*mut IRQState>, + _marker: PhantomData, +} + +impl InterruptSource { + /// Send a low (`false`) value to the interrupt sink. + pub fn lower(&self) { + self.set(false); + } + + /// Send a high-low pulse to the interrupt sink. + pub fn pulse(&self) { + self.set(true); + self.set(false); + } + + /// Send a high (`true`) value to the interrupt sink. + pub fn raise(&self) { + self.set(true); + } +} + +impl InterruptSource +where + c_int: From, +{ + /// Send `level` to the interrupt sink. + pub fn set(&self, level: T) { + let ptr = self.cell.get(); + // SAFETY: the pointer is retrieved under the BQL and remains valid + // until the BQL is released, which is after qemu_set_irq() is entered. + unsafe { + qemu_set_irq(ptr, level.into()); + } + } + + pub(crate) const fn as_ptr(&self) -> *mut *mut IRQState { + self.cell.as_ptr() + } +} + +impl Default for InterruptSource { + fn default() -> Self { + InterruptSource { + cell: BqlCell::new(ptr::null_mut()), + _marker: PhantomData, + } + } +} diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs index e5956cd5eb..0efbef4744 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -16,7 +16,9 @@ pub mod c_str; pub mod cell; pub mod definitions; pub mod device_class; +pub mod irq; pub mod offset_of; +pub mod sysbus; pub mod vmstate; pub mod zeroable; diff --git a/rust/qemu-api/src/sysbus.rs b/rust/qemu-api/src/sysbus.rs new file mode 100644 index 0000000000..4e192c7589 --- /dev/null +++ b/rust/qemu-api/src/sysbus.rs @@ -0,0 +1,27 @@ +// Copyright 2024 Red Hat, Inc. +// Author(s): Paolo Bonzini +// SPDX-License-Identifier: GPL-2.0-or-later + +use std::ptr::addr_of; + +pub use bindings::{SysBusDevice, SysBusDeviceClass}; + +use crate::{bindings, cell::bql_locked, irq::InterruptSource}; + +impl SysBusDevice { + /// Return `self` cast to a mutable pointer, for use in calls to C code. + const fn as_mut_ptr(&self) -> *mut SysBusDevice { + addr_of!(*self) as *mut _ + } + + /// Expose an interrupt source outside the device as a qdev GPIO output. + /// Note that the ordering of calls to `init_irq` is important, since + /// whoever creates the sysbus device will refer to the interrupts with + /// a number that corresponds to the order of calls to `init_irq`. + pub fn init_irq(&self, irq: &InterruptSource) { + assert!(bql_locked()); + unsafe { + bindings::sysbus_init_irq(self.as_mut_ptr(), irq.as_ptr()); + } + } +} -- cgit 1.4.1 From ab870fa106e0e3f48db2c5ef0507d107b1b41a21 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 5 Dec 2024 14:29:13 +0100 Subject: rust: add a bit operation module The bindgen supports `static inline` function binding since v0.64.0 as an experimental feature (`--wrap-static-fns`), and stabilizes it after v0.70.0. But the oldest version of bindgen supported by QEMU is v0.60.1, so there's no way to generate the binding for deposit64() which is `static inline` (in include/qemu/bitops.h). Instead, implement it by hand in Rust and make it available for all unsigned types through an IntegerExt trait. Since it only involves bit operations, the Rust version of the code is almost identical to the original C version, but it applies to more types than just u64. Signed-off-by: Zhao Liu Co-authored-by: Zhao Liu Signed-off-by: Paolo Bonzini --- rust/qemu-api/meson.build | 1 + rust/qemu-api/src/bitops.rs | 119 +++++++++++++++++++++++++++++++++++++++++++ rust/qemu-api/src/lib.rs | 1 + rust/qemu-api/src/prelude.rs | 2 + 4 files changed, 123 insertions(+) create mode 100644 rust/qemu-api/src/bitops.rs (limited to 'rust/qemu-api/src/lib.rs') diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index b927eb58c8..adcee66115 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -16,6 +16,7 @@ _qemu_api_rs = static_library( [ 'src/lib.rs', 'src/bindings.rs', + 'src/bitops.rs', 'src/cell.rs', 'src/c_str.rs', 'src/definitions.rs', diff --git a/rust/qemu-api/src/bitops.rs b/rust/qemu-api/src/bitops.rs new file mode 100644 index 0000000000..023ec1a998 --- /dev/null +++ b/rust/qemu-api/src/bitops.rs @@ -0,0 +1,119 @@ +// 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/lib.rs b/rust/qemu-api/src/lib.rs index 0efbef4744..9e007e1635 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -12,6 +12,7 @@ pub mod bindings; #[rustfmt::skip] pub mod prelude; +pub mod bitops; pub mod c_str; pub mod cell; pub mod definitions; diff --git a/rust/qemu-api/src/prelude.rs b/rust/qemu-api/src/prelude.rs index dfaddbd062..a39e228bab 100644 --- a/rust/qemu-api/src/prelude.rs +++ b/rust/qemu-api/src/prelude.rs @@ -2,5 +2,7 @@ // Author(s): Paolo Bonzini // SPDX-License-Identifier: GPL-2.0-or-later +pub use crate::bitops::IntegerExt; + pub use crate::cell::BqlCell; pub use crate::cell::BqlRefCell; -- cgit 1.4.1