3 files changed, 247 insertions, 0 deletions
diff --git a/rust/system/src/bindings.rs b/rust/system/src/bindings.rs
new file mode 100644
index 0000000000..43edd98807
--- /dev/null
+++ b/rust/system/src/bindings.rs
@@ -0,0 +1,41 @@
+// 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 constants and vtables; the Send and Sync requirements
+// are deferred to the unsafe callbacks that they contain
+unsafe impl Send for MemoryRegionOps {}
+unsafe impl Sync for MemoryRegionOps {}
+
+// SAFETY: this is a pure data struct
+unsafe impl Send for CoalescedMemoryRange {}
+unsafe impl Sync for CoalescedMemoryRange {}
+
+unsafe impl Zeroable for MemoryRegionOps__bindgen_ty_1 {}
+unsafe impl Zeroable for MemoryRegionOps__bindgen_ty_2 {}
+unsafe impl Zeroable for MemoryRegionOps {}
+unsafe impl Zeroable for MemTxAttrs {}
diff --git a/rust/system/src/lib.rs b/rust/system/src/lib.rs
new file mode 100644
index 0000000000..aafe9a866c
--- /dev/null
+++ b/rust/system/src/lib.rs
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+pub mod bindings;
+
+mod memory;
+pub use memory::*;
diff --git a/rust/system/src/memory.rs b/rust/system/src/memory.rs
new file mode 100644
index 0000000000..29568ed767
--- /dev/null
+++ b/rust/system/src/memory.rs
@@ -0,0 +1,200 @@
+// Copyright 2024 Red Hat, Inc.
+// Author(s): Paolo Bonzini <pbonzini@redhat.com>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+//! Bindings for `MemoryRegion`, `MemoryRegionOps` and `MemTxAttrs`
+
+use std::{
+    ffi::{c_uint, c_void, CStr, CString},
+    marker::PhantomData,
+};
+
+use common::{callbacks::FnCall, uninit::MaybeUninitField, zeroable::Zeroable, Opaque};
+use qom::prelude::*;
+
+use crate::bindings::{self, device_endian, memory_region_init_io};
+pub use crate::bindings::{hwaddr, MemTxAttrs};
+
+pub struct MemoryRegionOps<T>(
+    bindings::MemoryRegionOps,
+    // Note: quite often you'll see PhantomData<fn(&T)> mentioned when discussing
+    // covariance and contravariance; you don't need any of those to understand
+    // this usage of PhantomData.  Quite simply, MemoryRegionOps<T> *logically*
+    // holds callbacks that take an argument of type &T, except the type is erased
+    // before the callback is stored in the bindings::MemoryRegionOps field.
+    // The argument of PhantomData is a function pointer in order to represent
+    // that relationship; while that will also provide desirable and safe variance
+    // for T, variance is not the point but just a consequence.
+    PhantomData<fn(&T)>,
+);
+
+// SAFETY: When a *const T is passed to the callbacks, the call itself
+// is done in a thread-safe manner.  The invocation is okay as long as
+// T itself is `Sync`.
+unsafe impl<T: Sync> Sync for MemoryRegionOps<T> {}
+
+#[derive(Clone)]
+pub struct MemoryRegionOpsBuilder<T>(bindings::MemoryRegionOps, PhantomData<fn(&T)>);
+
+unsafe extern "C" fn memory_region_ops_read_cb<T, F: for<'a> FnCall<(&'a T, hwaddr, u32), u64>>(
+    opaque: *mut c_void,
+    addr: hwaddr,
+    size: c_uint,
+) -> u64 {
+    F::call((unsafe { &*(opaque.cast::<T>()) }, addr, size))
+}
+
+unsafe extern "C" fn memory_region_ops_write_cb<T, F: for<'a> FnCall<(&'a T, hwaddr, u64, u32)>>(
+    opaque: *mut c_void,
+    addr: hwaddr,
+    data: u64,
+    size: c_uint,
+) {
+    F::call((unsafe { &*(opaque.cast::<T>()) }, addr, data, size))
+}
+
+impl<T> MemoryRegionOpsBuilder<T> {
+    #[must_use]
+    pub const fn read<F: for<'a> FnCall<(&'a T, hwaddr, u32), u64>>(mut self, _f: &F) -> Self {
+        self.0.read = Some(memory_region_ops_read_cb::<T, F>);
+        self
+    }
+
+    #[must_use]
+    pub const fn write<F: for<'a> FnCall<(&'a T, hwaddr, u64, u32)>>(mut self, _f: &F) -> Self {
+        self.0.write = Some(memory_region_ops_write_cb::<T, F>);
+        self
+    }
+
+    #[must_use]
+    pub const fn big_endian(mut self) -> Self {
+        self.0.endianness = device_endian::DEVICE_BIG_ENDIAN;
+        self
+    }
+
+    #[must_use]
+    pub const fn little_endian(mut self) -> Self {
+        self.0.endianness = device_endian::DEVICE_LITTLE_ENDIAN;
+        self
+    }
+
+    #[must_use]
+    pub const fn native_endian(mut self) -> Self {
+        self.0.endianness = device_endian::DEVICE_NATIVE_ENDIAN;
+        self
+    }
+
+    #[must_use]
+    pub const fn valid_sizes(mut self, min: u32, max: u32) -> Self {
+        self.0.valid.min_access_size = min;
+        self.0.valid.max_access_size = max;
+        self
+    }
+
+    #[must_use]
+    pub const fn valid_unaligned(mut self) -> Self {
+        self.0.valid.unaligned = true;
+        self
+    }
+
+    #[must_use]
+    pub const fn impl_sizes(mut self, min: u32, max: u32) -> Self {
+        self.0.impl_.min_access_size = min;
+        self.0.impl_.max_access_size = max;
+        self
+    }
+
+    #[must_use]
+    pub const fn impl_unaligned(mut self) -> Self {
+        self.0.impl_.unaligned = true;
+        self
+    }
+
+    #[must_use]
+    pub const fn build(self) -> MemoryRegionOps<T> {
+        MemoryRegionOps::<T>(self.0, PhantomData)
+    }
+
+    #[must_use]
+    pub const fn new() -> Self {
+        Self(bindings::MemoryRegionOps::ZERO, PhantomData)
+    }
+}
+
+impl<T> Default for MemoryRegionOpsBuilder<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+/// A safe wrapper around [`bindings::MemoryRegion`].
+#[repr(transparent)]
+#[derive(qemu_api_macros::Wrapper)]
+pub struct MemoryRegion(Opaque<bindings::MemoryRegion>);
+
+unsafe impl Send for MemoryRegion {}
+unsafe impl Sync for MemoryRegion {}
+
+impl MemoryRegion {
+    // inline to ensure that it is not included in tests, which only
+    // link to hwcore and qom.  FIXME: inlining is actually the opposite
+    // of what we want, since this is the type-erased version of the
+    // init_io function below.  Look into splitting the qemu_api crate.
+    #[inline(always)]
+    unsafe fn do_init_io(
+        slot: *mut bindings::MemoryRegion,
+        owner: *mut bindings::Object,
+        ops: &'static bindings::MemoryRegionOps,
+        name: &'static str,
+        size: u64,
+    ) {
+        unsafe {
+            let cstr = CString::new(name).unwrap();
+            memory_region_init_io(
+                slot,
+                owner,
+                ops,
+                owner.cast::<c_void>(),
+                cstr.as_ptr(),
+                size,
+            );
+        }
+    }
+
+    pub fn init_io<T: IsA<Object>>(
+        this: &mut MaybeUninitField<'_, T, Self>,
+        ops: &'static MemoryRegionOps<T>,
+        name: &'static str,
+        size: u64,
+    ) {
+        unsafe {
+            Self::do_init_io(
+                this.as_mut_ptr().cast(),
+                MaybeUninitField::parent_mut(this).cast(),
+                &ops.0,
+                name,
+                size,
+            );
+        }
+    }
+}
+
+unsafe impl ObjectType for MemoryRegion {
+    type Class = bindings::MemoryRegionClass;
+    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
+/// attributes are specified.
+///
+/// Bus masters which don't specify any attributes will get this,
+/// which has all attribute bits clear except the topmost one
+/// (so that we can distinguish "all attributes deliberately clear"
+/// from "didn't specify" if necessary).
+pub const MEMTXATTRS_UNSPECIFIED: MemTxAttrs = MemTxAttrs {
+    unspecified: true,
+    ..Zeroable::ZERO
+};