From: Manos Pitsidianakis Date: Mon, 8 Sep 2025 10:49:38 +0000 (+0200) Subject: rust: add qdev Device derive macro X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a71df7e143b57427c1f8a917654e7b0ed1ceb919;p=thirdparty%2Fqemu.git rust: add qdev Device derive macro Add derive macro for declaring qdev properties directly above the field definitions. To do this, we split DeviceImpl::properties method on a separate trait so we can implement only that part in the derive macro expansion (we cannot partially implement the DeviceImpl trait). Adding a `property` attribute above the field declaration will generate a `qemu_api::bindings::Property` array member in the device's property list. Signed-off-by: Manos Pitsidianakis Link: https://lore.kernel.org/r/20250711-rust-qdev-properties-v3-1-e198624416fb@linaro.org 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 ceb71dd99b6..37944635202 100644 --- a/rust/hw/char/pl011/src/device.rs +++ b/rust/hw/char/pl011/src/device.rs @@ -9,7 +9,6 @@ use std::{ }; use qemu_api::{ - bindings::{qdev_prop_bool, qdev_prop_chr}, chardev::{CharBackend, Chardev, Event}, impl_vmstate_forward, irq::{IRQState, InterruptSource}, @@ -17,7 +16,7 @@ use qemu_api::{ log_mask_ln, memory::{hwaddr, MemoryRegion, MemoryRegionOps, MemoryRegionOpsBuilder}, prelude::*, - qdev::{Clock, ClockEvent, DeviceImpl, DeviceState, Property, ResetType, ResettablePhasesImpl}, + qdev::{Clock, ClockEvent, DeviceImpl, DeviceState, ResetType, ResettablePhasesImpl}, qom::{ObjectImpl, Owned, ParentField, ParentInit}, static_assert, sysbus::{SysBusDevice, SysBusDeviceImpl}, @@ -105,12 +104,13 @@ pub struct PL011Registers { } #[repr(C)] -#[derive(qemu_api_macros::Object)] +#[derive(qemu_api_macros::Object, qemu_api_macros::Device)] /// PL011 Device Model in QEMU pub struct PL011State { pub parent_obj: ParentField, pub iomem: MemoryRegion, #[doc(alias = "chr")] + #[property(rename = "chardev")] pub char_backend: CharBackend, pub regs: BqlRefCell, /// QEMU interrupts @@ -129,6 +129,7 @@ pub struct PL011State { #[doc(alias = "clk")] pub clock: Owned, #[doc(alias = "migrate_clk")] + #[property(rename = "migrate-clk", default = true)] pub migrate_clock: bool, } @@ -176,9 +177,6 @@ impl ObjectImpl for PL011State { } impl DeviceImpl for PL011State { - fn properties() -> &'static [Property] { - &PL011_PROPERTIES - } fn vmsd() -> Option<&'static VMStateDescription> { Some(&VMSTATE_PL011) } @@ -690,7 +688,7 @@ pub unsafe extern "C" fn pl011_create( } #[repr(C)] -#[derive(qemu_api_macros::Object)] +#[derive(qemu_api_macros::Object, qemu_api_macros::Device)] /// PL011 Luminary device model. pub struct PL011Luminary { parent_obj: ParentField, @@ -782,22 +780,3 @@ pub static VMSTATE_PL011: VMStateDescription = VMStateDescription { }, ..Zeroable::ZERO }; - -qemu_api::declare_properties! { - PL011_PROPERTIES, - qemu_api::define_property!( - c"chardev", - PL011State, - char_backend, - unsafe { &qdev_prop_chr }, - CharBackend - ), - qemu_api::define_property!( - c"migrate-clk", - PL011State, - migrate_clock, - unsafe { &qdev_prop_bool }, - bool, - default = true - ), -} diff --git a/rust/hw/timer/hpet/src/device.rs b/rust/hw/timer/hpet/src/device.rs index acf7251029e..01d5a0dd70c 100644 --- a/rust/hw/timer/hpet/src/device.rs +++ b/rust/hw/timer/hpet/src/device.rs @@ -1031,11 +1031,15 @@ static VMSTATE_HPET: VMStateDescription = VMStateDescription { ..Zeroable::ZERO }; -impl DeviceImpl for HPETState { +// SAFETY: HPET_PROPERTIES is a valid Property array constructed with the +// qemu_api::declare_properties macro. +unsafe impl qemu_api::qdev::DevicePropertiesImpl for HPETState { fn properties() -> &'static [Property] { &HPET_PROPERTIES } +} +impl DeviceImpl for HPETState { fn vmsd() -> Option<&'static VMStateDescription> { Some(&VMSTATE_HPET) } diff --git a/rust/qemu-api-macros/src/lib.rs b/rust/qemu-api-macros/src/lib.rs index 959726efe6d..97b2c214b62 100644 --- a/rust/qemu-api-macros/src/lib.rs +++ b/rust/qemu-api-macros/src/lib.rs @@ -3,10 +3,11 @@ // SPDX-License-Identifier: GPL-2.0-or-later use proc_macro::TokenStream; -use quote::quote; +use quote::{quote, quote_spanned, ToTokens}; use syn::{ - parse_macro_input, parse_quote, punctuated::Punctuated, spanned::Spanned, token::Comma, Data, - DeriveInput, Error, Field, Fields, FieldsUnnamed, Ident, Meta, Path, Token, Variant, + parse::Parse, parse_macro_input, parse_quote, punctuated::Punctuated, spanned::Spanned, + token::Comma, Data, DeriveInput, Error, Field, Fields, FieldsUnnamed, Ident, Meta, Path, Token, + Variant, }; mod bits; use bits::BitsConstInternal; @@ -152,6 +153,151 @@ fn derive_opaque_or_error(input: DeriveInput) -> Result, + defval: Option, +} + +impl Parse for DeviceProperty { + fn parse(input: syn::parse::ParseStream) -> syn::Result { + let _: syn::Token![#] = input.parse()?; + let bracketed; + _ = syn::bracketed!(bracketed in input); + let attribute = bracketed.parse::()?; + debug_assert_eq!(&attribute.to_string(), "property"); + let mut retval = Self { + rename: None, + defval: None, + }; + let content; + _ = syn::parenthesized!(content in bracketed); + while !content.is_empty() { + let value: syn::Ident = content.parse()?; + if value == "rename" { + let _: syn::Token![=] = content.parse()?; + if retval.rename.is_some() { + return Err(syn::Error::new( + value.span(), + "`rename` can only be used at most once", + )); + } + if content.peek(syn::LitStr) { + retval.rename = Some(DevicePropertyName::Str(content.parse::()?)); + } else { + retval.rename = + Some(DevicePropertyName::CStr(content.parse::()?)); + } + } else if value == "default" { + let _: syn::Token![=] = content.parse()?; + if retval.defval.is_some() { + return Err(syn::Error::new( + value.span(), + "`default` can only be used at most once", + )); + } + retval.defval = Some(content.parse()?); + } else { + return Err(syn::Error::new( + value.span(), + format!("unrecognized field `{value}`"), + )); + } + + if !content.is_empty() { + let _: syn::Token![,] = content.parse()?; + } + } + Ok(retval) + } +} + +#[proc_macro_derive(Device, attributes(property))] +pub fn derive_device(input: TokenStream) -> TokenStream { + let input = parse_macro_input!(input as DeriveInput); + + derive_device_or_error(input) + .unwrap_or_else(syn::Error::into_compile_error) + .into() +} + +fn derive_device_or_error(input: DeriveInput) -> Result { + is_c_repr(&input, "#[derive(Device)]")?; + let properties: Vec<(syn::Field, DeviceProperty)> = get_fields(&input, "#[derive(Device)]")? + .iter() + .flat_map(|f| { + f.attrs + .iter() + .filter(|a| a.path().is_ident("property")) + .map(|a| Ok((f.clone(), syn::parse2(a.to_token_stream())?))) + }) + .collect::, Error>>()?; + let name = &input.ident; + let mut properties_expanded = vec![]; + + for (field, prop) in properties { + let DeviceProperty { rename, defval } = prop; + let field_name = field.ident.unwrap(); + macro_rules! str_to_c_str { + ($value:expr, $span:expr) => {{ + let (value, span) = ($value, $span); + let cstr = std::ffi::CString::new(value.as_str()).map_err(|err| { + Error::new( + span, + format!( + "Property name `{value}` cannot be represented as a C string: {err}" + ), + ) + })?; + let cstr_lit = syn::LitCStr::new(&cstr, span); + Ok(quote! { #cstr_lit }) + }}; + } + + let prop_name = rename.map_or_else( + || str_to_c_str!(field_name.to_string(), field_name.span()), + |rename| -> Result { + match rename { + DevicePropertyName::CStr(cstr_lit) => Ok(quote! { #cstr_lit }), + DevicePropertyName::Str(str_lit) => { + str_to_c_str!(str_lit.value(), str_lit.span()) + } + } + }, + )?; + let field_ty = field.ty.clone(); + let qdev_prop = quote! { <#field_ty as ::qemu_api::qdev::QDevProp>::VALUE }; + let set_default = defval.is_some(); + let defval = defval.unwrap_or(syn::Expr::Verbatim(quote! { 0 })); + properties_expanded.push(quote! { + ::qemu_api::bindings::Property { + name: ::std::ffi::CStr::as_ptr(#prop_name), + info: #qdev_prop , + offset: ::core::mem::offset_of!(#name, #field_name) as isize, + set_default: #set_default, + defval: ::qemu_api::bindings::Property__bindgen_ty_1 { u: #defval as u64 }, + ..::qemu_api::zeroable::Zeroable::ZERO + } + }); + } + + Ok(quote_spanned! {input.span() => + unsafe impl ::qemu_api::qdev::DevicePropertiesImpl for #name { + fn properties() -> &'static [::qemu_api::bindings::Property] { + static PROPERTIES: &[::qemu_api::bindings::Property] = &[#(#properties_expanded),*]; + + PROPERTIES + } + } + }) +} + #[proc_macro_derive(Wrapper)] pub fn derive_opaque(input: TokenStream) -> TokenStream { let input = parse_macro_input!(input as DeriveInput); diff --git a/rust/qemu-api-macros/src/tests.rs b/rust/qemu-api-macros/src/tests.rs index 6028cdbc4c3..aafffcdce91 100644 --- a/rust/qemu-api-macros/src/tests.rs +++ b/rust/qemu-api-macros/src/tests.rs @@ -36,6 +36,117 @@ macro_rules! derive_compile { }}; } +#[test] +fn test_derive_device() { + // Check that repr(C) is used + derive_compile_fail!( + derive_device_or_error, + quote! { + #[derive(Device)] + struct Foo { + _unused: [u8; 0], + } + }, + "#[repr(C)] required for #[derive(Device)]" + ); + // Check that invalid/misspelled attributes raise an error + derive_compile_fail!( + derive_device_or_error, + quote! { + #[repr(C)] + #[derive(Device)] + struct DummyState { + #[property(defalt = true)] + migrate_clock: bool, + } + }, + "unrecognized field `defalt`" + ); + // Check that repeated attributes are not allowed: + derive_compile_fail!( + derive_device_or_error, + quote! { + #[repr(C)] + #[derive(Device)] + struct DummyState { + #[property(rename = "migrate-clk", rename = "migrate-clk", default = true)] + migrate_clock: bool, + } + }, + "`rename` can only be used at most once" + ); + derive_compile_fail!( + derive_device_or_error, + quote! { + #[repr(C)] + #[derive(Device)] + struct DummyState { + #[property(default = true, default = true)] + migrate_clock: bool, + } + }, + "`default` can only be used at most once" + ); + // Check that the field name is preserved when `rename` isn't used: + derive_compile!( + derive_device_or_error, + quote! { + #[repr(C)] + #[derive(Device)] + pub struct DummyState { + parent: ParentField, + #[property(default = true)] + migrate_clock: bool, + } + }, + quote! { + unsafe impl ::qemu_api::qdev::DevicePropertiesImpl for DummyState { + fn properties() -> &'static [::qemu_api::bindings::Property] { + static PROPERTIES: &[::qemu_api::bindings::Property] = + &[::qemu_api::bindings::Property { + name: ::std::ffi::CStr::as_ptr(c"migrate_clock"), + info: ::VALUE, + offset: ::core::mem::offset_of!(DummyState, migrate_clock) as isize, + set_default: true, + defval: ::qemu_api::bindings::Property__bindgen_ty_1 { u: true as u64 }, + ..::qemu_api::zeroable::Zeroable::ZERO + }]; + PROPERTIES + } + } + } + ); + // Check that `rename` value is used for the property name when used: + derive_compile!( + derive_device_or_error, + quote! { + #[repr(C)] + #[derive(Device)] + pub struct DummyState { + parent: ParentField, + #[property(rename = "migrate-clk", default = true)] + migrate_clock: bool, + } + }, + quote! { + unsafe impl ::qemu_api::qdev::DevicePropertiesImpl for DummyState { + fn properties() -> &'static [::qemu_api::bindings::Property] { + static PROPERTIES: &[::qemu_api::bindings::Property] = + &[::qemu_api::bindings::Property { + name: ::std::ffi::CStr::as_ptr(c"migrate-clk"), + info: ::VALUE, + offset: ::core::mem::offset_of!(DummyState, migrate_clock) as isize, + set_default: true, + defval: ::qemu_api::bindings::Property__bindgen_ty_1 { u: true as u64 }, + ..::qemu_api::zeroable::Zeroable::ZERO + }]; + PROPERTIES + } + } + } + ); +} + #[test] fn test_derive_object() { derive_compile_fail!( diff --git a/rust/qemu-api/src/qdev.rs b/rust/qemu-api/src/qdev.rs index 52d54a4494e..6a58a00e3fc 100644 --- a/rust/qemu-api/src/qdev.rs +++ b/rust/qemu-api/src/qdev.rs @@ -101,8 +101,67 @@ unsafe extern "C" fn rust_resettable_exit_fn( T::EXIT.unwrap()(unsafe { state.as_ref() }, typ); } +/// Helper trait to return pointer to a [`bindings::PropertyInfo`] for a type. +/// +/// This trait is used by [`qemu_api_macros::Device`] derive macro. +/// +/// Base types that already have `qdev_prop_*` globals in the QEMU API should +/// use those values as exported by the [`bindings`] module, instead of +/// redefining them. +/// +/// # Safety +/// +/// This trait is marked as `unsafe` because currently having a `const` refer to +/// an `extern static` as a reference instead of a raw pointer results in this +/// compiler error: +/// +/// ```text +/// constructing invalid value: encountered reference to `extern` static in `const` +/// ``` +/// +/// This is because the compiler generally might dereference a normal reference +/// during const evaluation, but not in this case (if it did, it'd need to +/// dereference the raw pointer so this would fail to compile). +/// +/// It is the implementer's responsibility to provide a valid +/// [`bindings::PropertyInfo`] pointer for the trait implementation to be safe. +pub unsafe trait QDevProp { + const VALUE: *const bindings::PropertyInfo; +} + +/// Use [`bindings::qdev_prop_bool`] for `bool`. +unsafe impl QDevProp for bool { + const VALUE: *const bindings::PropertyInfo = unsafe { &bindings::qdev_prop_bool }; +} + +/// Use [`bindings::qdev_prop_uint64`] for `u64`. +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 { + const VALUE: *const bindings::PropertyInfo = unsafe { &bindings::qdev_prop_chr }; +} + +/// Trait to define device properties. +/// +/// # Safety +/// +/// Caller is responsible for the validity of properties array. +pub unsafe trait DevicePropertiesImpl { + /// An array providing the properties that the user can set on the + /// device. Not a `const` because referencing statics in constants + /// is unstable until Rust 1.83.0. + fn properties() -> &'static [Property] { + &[] + } +} + /// Trait providing the contents of [`DeviceClass`]. -pub trait DeviceImpl: ObjectImpl + ResettablePhasesImpl + IsA { +pub trait DeviceImpl: + ObjectImpl + ResettablePhasesImpl + DevicePropertiesImpl + IsA +{ /// _Realization_ is the second stage of device creation. It contains /// all operations that depend on device properties and can fail (note: /// this is not yet supported for Rust devices). @@ -111,13 +170,6 @@ pub trait DeviceImpl: ObjectImpl + ResettablePhasesImpl + IsA { /// with the function pointed to by `REALIZE`. const REALIZE: Option Result<()>> = None; - /// An array providing the properties that the user can set on the - /// device. Not a `const` because referencing statics in constants - /// is unstable until Rust 1.83.0. - fn properties() -> &'static [Property] { - &[] - } - /// A `VMStateDescription` providing the migration format for the device /// Not a `const` because referencing statics in constants is unstable /// until Rust 1.83.0. @@ -175,7 +227,7 @@ impl DeviceClass { if let Some(vmsd) = ::vmsd() { self.vmsd = vmsd; } - let prop = ::properties(); + let prop = ::properties(); if !prop.is_empty() { unsafe { bindings::device_class_set_props_n(self, prop.as_ptr(), prop.len()); diff --git a/rust/qemu-api/tests/tests.rs b/rust/qemu-api/tests/tests.rs index a658a49fcfd..aff3eecd654 100644 --- a/rust/qemu-api/tests/tests.rs +++ b/rust/qemu-api/tests/tests.rs @@ -5,11 +5,10 @@ use std::{ffi::CStr, ptr::addr_of}; use qemu_api::{ - bindings::{module_call_init, module_init_type, qdev_prop_bool}, + bindings::{module_call_init, module_init_type}, cell::{self, BqlCell}, - declare_properties, define_property, prelude::*, - qdev::{DeviceImpl, DeviceState, Property, ResettablePhasesImpl}, + qdev::{DeviceImpl, DeviceState, ResettablePhasesImpl}, qom::{ObjectImpl, ParentField}, sysbus::SysBusDevice, vmstate::VMStateDescription, @@ -26,9 +25,10 @@ pub static VMSTATE: VMStateDescription = VMStateDescription { }; #[repr(C)] -#[derive(qemu_api_macros::Object)] +#[derive(qemu_api_macros::Object, qemu_api_macros::Device)] pub struct DummyState { parent: ParentField, + #[property(rename = "migrate-clk", default = true)] migrate_clock: bool, } @@ -44,17 +44,6 @@ impl DummyClass { } } -declare_properties! { - DUMMY_PROPERTIES, - define_property!( - c"migrate-clk", - DummyState, - migrate_clock, - unsafe { &qdev_prop_bool }, - bool - ), -} - unsafe impl ObjectType for DummyState { type Class = DummyClass; const TYPE_NAME: &'static CStr = c"dummy"; @@ -69,16 +58,13 @@ impl ObjectImpl for DummyState { impl ResettablePhasesImpl for DummyState {} impl DeviceImpl for DummyState { - fn properties() -> &'static [Property] { - &DUMMY_PROPERTIES - } fn vmsd() -> Option<&'static VMStateDescription> { Some(&VMSTATE) } } #[repr(C)] -#[derive(qemu_api_macros::Object)] +#[derive(qemu_api_macros::Object, qemu_api_macros::Device)] pub struct DummyChildState { parent: ParentField, }