From: Paolo Bonzini Date: Thu, 31 Oct 2024 08:56:15 +0000 (+0100) Subject: rust: qom: split ObjectType from ObjectImpl trait X-Git-Tag: v10.0.0-rc0~123^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7bd8e3ef63330e870cf4644d21c285cce35c703d;p=thirdparty%2Fqemu.git rust: qom: split ObjectType from ObjectImpl trait Define a separate trait for fields that also applies to classes that are defined by C code. This makes it possible to add metadata to core classes, which has multiple uses: - it makes it possible to access the parent struct's TYPE_* for types that are defined in Rust code, and to avoid repeating it in every subclass - implementors of ObjectType will be allowed to implement the IsA<> trait and therefore to perform typesafe casts from one class to another. - in the future, an ObjectType could be created with Foo::new() in a type-safe manner, without having to pass a TYPE_* constant. Reviewed-by: Zhao Liu Signed-off-by: Paolo Bonzini --- diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs index b9f8fb134b5..0ab825b1ca4 100644 --- a/rust/hw/char/pl011/src/device.rs +++ b/rust/hw/char/pl011/src/device.rs @@ -12,9 +12,10 @@ use qemu_api::{ bindings::{self, *}, c_str, definitions::ObjectImpl, - device_class::{DeviceImpl, TYPE_SYS_BUS_DEVICE}, + device_class::DeviceImpl, impl_device_class, irq::InterruptSource, + prelude::*, }; use crate::{ @@ -106,10 +107,13 @@ pub struct PL011State { device_id: DeviceId, } -impl ObjectImpl for PL011State { +unsafe impl ObjectType for PL011State { type Class = PL011Class; const TYPE_NAME: &'static CStr = crate::TYPE_PL011; - const PARENT_TYPE_NAME: Option<&'static CStr> = Some(TYPE_SYS_BUS_DEVICE); +} + +impl ObjectImpl for PL011State { + const PARENT_TYPE_NAME: Option<&'static CStr> = Some(::TYPE_NAME); const INSTANCE_INIT: Option = Some(Self::init); } @@ -640,10 +644,13 @@ impl PL011Luminary { } } -impl ObjectImpl for PL011Luminary { +unsafe impl ObjectType for PL011Luminary { type Class = PL011LuminaryClass; const TYPE_NAME: &'static CStr = crate::TYPE_PL011_LUMINARY; - const PARENT_TYPE_NAME: Option<&'static CStr> = Some(crate::TYPE_PL011); +} + +impl ObjectImpl for PL011Luminary { + const PARENT_TYPE_NAME: Option<&'static CStr> = Some(::TYPE_NAME); const INSTANCE_INIT: Option = Some(Self::init); } diff --git a/rust/qemu-api/src/definitions.rs b/rust/qemu-api/src/definitions.rs index f2970758986..b98a6926785 100644 --- a/rust/qemu-api/src/definitions.rs +++ b/rust/qemu-api/src/definitions.rs @@ -26,25 +26,40 @@ unsafe extern "C" fn rust_instance_post_init(obj: *mut Object) { T::INSTANCE_POST_INIT.unwrap()(unsafe { &mut *obj.cast::() }) } -/// Trait a type must implement to be registered with QEMU. +/// Trait exposed by all structs corresponding to QOM objects. /// /// # Safety /// -/// - the struct must be `#[repr(C)]` +/// 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 /// -/// - `Class` and `TYPE` must match the data in the `TypeInfo` (this is -/// automatic if the class is defined via `ObjectImpl`). +/// For classes declared in Rust and implementing [`ObjectImpl`]: +/// +/// - the struct must be `#[repr(C)]`; /// /// - the first field of the struct must be of the instance struct corresponding -/// to the superclass declared as `PARENT_TYPE_NAME` -pub trait ObjectImpl: ClassInitImpl + Sized { +/// to the superclass, as declared in `ObjectImpl::PARENT_TYPE_NAME` +/// +/// - likewise, the first field of the `Class` must be of the class struct +/// corresponding to the superclass +pub unsafe trait ObjectType: Sized { /// The QOM class object corresponding to this struct. Not used yet. 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; +} +/// Trait a type must implement to be registered with QEMU. +pub trait ObjectImpl: ObjectType + ClassInitImpl { /// The parent of the type. This should match the first field of /// the struct that implements `ObjectImpl`: const PARENT_TYPE_NAME: Option<&'static CStr>; diff --git a/rust/qemu-api/src/device_class.rs b/rust/qemu-api/src/device_class.rs index f25904be4f6..03d03feee83 100644 --- a/rust/qemu-api/src/device_class.rs +++ b/rust/qemu-api/src/device_class.rs @@ -6,6 +6,7 @@ use std::{ffi::CStr, os::raw::c_void}; use crate::{ bindings::{self, DeviceClass, DeviceState, Error, ObjectClass, Property, VMStateDescription}, + prelude::*, zeroable::Zeroable, }; @@ -146,8 +147,8 @@ macro_rules! declare_properties { }; } -// workaround until we can use --generate-cstr in bindgen. -pub const TYPE_DEVICE: &CStr = - unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_DEVICE) }; -pub const TYPE_SYS_BUS_DEVICE: &CStr = - unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_SYS_BUS_DEVICE) }; +unsafe impl ObjectType for bindings::DeviceState { + type Class = bindings::DeviceClass; + const TYPE_NAME: &'static CStr = + unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_DEVICE) }; +} diff --git a/rust/qemu-api/src/prelude.rs b/rust/qemu-api/src/prelude.rs index a39e228babf..1b8677b2d9a 100644 --- a/rust/qemu-api/src/prelude.rs +++ b/rust/qemu-api/src/prelude.rs @@ -6,3 +6,5 @@ pub use crate::bitops::IntegerExt; pub use crate::cell::BqlCell; pub use crate::cell::BqlRefCell; + +pub use crate::definitions::ObjectType; diff --git a/rust/qemu-api/src/sysbus.rs b/rust/qemu-api/src/sysbus.rs index 4e192c75898..5ee068541cf 100644 --- a/rust/qemu-api/src/sysbus.rs +++ b/rust/qemu-api/src/sysbus.rs @@ -2,11 +2,17 @@ // Author(s): Paolo Bonzini // SPDX-License-Identifier: GPL-2.0-or-later -use std::ptr::addr_of; +use std::{ffi::CStr, ptr::addr_of}; pub use bindings::{SysBusDevice, SysBusDeviceClass}; -use crate::{bindings, cell::bql_locked, irq::InterruptSource}; +use crate::{bindings, cell::bql_locked, irq::InterruptSource, prelude::*}; + +unsafe impl ObjectType for SysBusDevice { + type Class = SysBusDeviceClass; + const TYPE_NAME: &'static CStr = + unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_SYS_BUS_DEVICE) }; +} impl SysBusDevice { /// Return `self` cast to a mutable pointer, for use in calls to C code. diff --git a/rust/qemu-api/tests/tests.rs b/rust/qemu-api/tests/tests.rs index b8b12a40422..1d027dd6527 100644 --- a/rust/qemu-api/tests/tests.rs +++ b/rust/qemu-api/tests/tests.rs @@ -5,12 +5,8 @@ use std::ffi::CStr; use qemu_api::{ - bindings::*, - c_str, declare_properties, define_property, - definitions::ObjectImpl, - device_class::{self, DeviceImpl}, - impl_device_class, - zeroable::Zeroable, + bindings::*, c_str, declare_properties, define_property, definitions::ObjectImpl, + device_class::DeviceImpl, impl_device_class, prelude::*, zeroable::Zeroable, }; #[test] @@ -46,10 +42,15 @@ fn test_device_decl_macros() { ), } - impl ObjectImpl for DummyState { + unsafe impl ObjectType for DummyState { type Class = DummyClass; const TYPE_NAME: &'static CStr = c_str!("dummy"); - const PARENT_TYPE_NAME: Option<&'static CStr> = Some(device_class::TYPE_DEVICE); + } + + impl ObjectImpl for DummyState { + const PARENT_TYPE_NAME: Option<&'static CStr> = + Some(::TYPE_NAME); + const ABSTRACT: bool = false; } impl DeviceImpl for DummyState {