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charset="US-ASCII"; x-default=true Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.187, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-rust@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: QEMU Rust-related patches and discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 31 Dec 2024 00:24:00 -0000 Signed-off-by: Paolo Bonzini --- rust/qemu-api/src/vmstate.rs | 61 ++++++++++++++++++++++++++++++++++-- 1 file changed, 58 insertions(+), 3 deletions(-) diff --git a/rust/qemu-api/src/vmstate.rs b/rust/qemu-api/src/vmstate.rs index edd0cbff162..b59a4b66339 100644 --- a/rust/qemu-api/src/vmstate.rs +++ b/rust/qemu-api/src/vmstate.rs @@ -4,13 +4,18 @@ //! Helper macros to declare migration state for device models. //! -//! This module includes three families of macros: +//! This module includes four families of macros: //! //! * [`vmstate_unused!`](crate::vmstate_unused) and //! [`vmstate_of!`](crate::vmstate_of), which are used to express the //! migration format for a struct. This is based on the [`VMState`] trait, //! which is defined by all migrateable types. //! +//! * [`impl_vmstate_forward`](crate::impl_vmstate_forward) and +//! [`impl_vmstate_bitsized`](crate::impl_vmstate_bitsized), which help with +//! the definition of the [`VMState`] trait (respectively for transparent +//! structs and for `bilge`-defined types) +//! //! * helper macros to declare a device model state struct, in particular //! [`vmstate_subsections`](crate::vmstate_subsections) and //! [`vmstate_fields`](crate::vmstate_fields). @@ -131,7 +136,9 @@ macro_rules! info_enum_to_ref { /// # Safety /// /// The contents of this trait go straight into structs that are parsed by C -/// code and used to introspect into other structs. Be careful. +/// code and used to introspect into other structs. Generally, you don't need +/// to implement it except via macros that do it for you, such as +/// `impl_vmstate_bitsized!`. pub unsafe trait VMState { /// The `info` member of a `VMStateField` is a pointer and as such cannot /// yet be included in the [`BASE`](VMState::BASE) associated constant; @@ -185,7 +192,9 @@ pub const fn vmstate_varray_flag(_: PhantomData) -> VMStateField /// * an array of any of the above /// /// In order to support other types, the trait `VMState` must be implemented -/// for them. +/// for them. The macros +/// [`impl_vmstate_bitsized!`](crate::impl_vmstate_bitsized) +/// and [`impl_vmstate_forward!`](crate::impl_vmstate_forward) help with this. #[macro_export] macro_rules! vmstate_of { ($struct_name:ty, $field_name:ident $([0 .. $num:tt $(* $factor:expr)?])? $(,)?) => { @@ -263,6 +272,32 @@ pub const fn with_varray_multiply(mut self, num: u32) -> VMStateField { } } +/// This macro can be used (by just passing it a type) to forward the `VMState` +/// trait to the first field of a tuple. This is a workaround for lack of +/// support of nested [`offset_of`](core::mem::offset_of) until Rust 1.82.0. +/// +/// # Examples +/// +/// ``` +/// # use qemu_api::vmstate::impl_vmstate_forward; +/// pub struct Fifo([u8; 16]); +/// impl_vmstate_forward!(Fifo); +/// ``` +#[macro_export] +macro_rules! impl_vmstate_forward { + // This is similar to impl_vmstate_transparent below, but it + // uses the same trick as vmstate_of! to obtain the type of + // the first field of the tuple + ($tuple:ty) => { + unsafe impl $crate::vmstate::VMState for $tuple { + const SCALAR_TYPE: $crate::vmstate::VMStateFieldType = + $crate::call_func_with_field!($crate::vmstate::vmstate_scalar_type, $tuple, 0); + const BASE: $crate::bindings::VMStateField = + $crate::call_func_with_field!($crate::vmstate::vmstate_base, $tuple, 0); + } + }; +} + // Transparent wrappers: just use the internal type macro_rules! impl_vmstate_transparent { @@ -283,6 +318,26 @@ unsafe impl<$base> VMState for $type where $base: VMState $($where)* { impl_vmstate_transparent!(crate::cell::BqlCell where T: VMState); impl_vmstate_transparent!(crate::cell::BqlRefCell where T: VMState); +#[macro_export] +macro_rules! impl_vmstate_bitsized { + ($type:ty) => { + unsafe impl $crate::vmstate::VMState for $type { + const SCALAR_TYPE: $crate::vmstate::VMStateFieldType = + <<<$type as ::bilge::prelude::Bitsized>::ArbitraryInt + as ::bilge::prelude::Number>::UnderlyingType + as $crate::vmstate::VMState>::SCALAR_TYPE; + const BASE: $crate::bindings::VMStateField = + <<<$type as ::bilge::prelude::Bitsized>::ArbitraryInt + as ::bilge::prelude::Number>::UnderlyingType + as $crate::vmstate::VMState>::BASE; + const VARRAY_FLAG: $crate::bindings::VMStateFlags = + <<<$type as ::bilge::prelude::Bitsized>::ArbitraryInt + as ::bilge::prelude::Number>::UnderlyingType + as $crate::vmstate::VMState>::VARRAY_FLAG; + } + }; +} + // Scalar types using predefined VMStateInfos macro_rules! impl_vmstate_scalar { -- 2.47.1