Re: [PULL 18/18] rust: migration: allow passing ParentField<> to vmstate_of!

[Richard Henderson <richard.henderson@linaro.org>]

On 10/28/25 18:34, Paolo Bonzini wrote:
> The common superclass for devices could have its own migration state;
> for it to be included in the subclass's VMState, ParentField<> must
> implement the VMState trait.
> 
> Reported-by: Chen Miao <chenmiao@openatom.club>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   roms/opensbi                  | 2 +-
>   rust/migration/src/vmstate.rs | 3 ++-
>   rust/qom/src/qom.rs           | 3 ++-
>   3 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/roms/opensbi b/roms/opensbi
> index a32a9106911..43cace6c367 160000
> --- a/roms/opensbi
> +++ b/roms/opensbi
> @@ -1 +1 @@
> -Subproject commit a32a91069119e7a5aa31e6bc51d5e00860be3d80
> +Subproject commit 43cace6c3671e5172d0df0a8963e552bb04b7b20

Spurious subproject change.


r~

> diff --git a/rust/migration/src/vmstate.rs b/rust/migration/src/vmstate.rs
> index 42e5df8d818..5a237c409ac 100644
> --- a/rust/migration/src/vmstate.rs
> +++ b/rust/migration/src/vmstate.rs
> @@ -268,7 +268,7 @@ macro_rules! impl_vmstate_transparent {
>       ($type:ty where $base:tt: VMState $($where:tt)*) => {
>           unsafe impl<$base> $crate::vmstate::VMState for $type where $base: $crate::vmstate::VMState $($where)* {
>               const BASE: $crate::vmstate::VMStateField = $crate::vmstate::VMStateField {
> -                size: mem::size_of::<$type>(),
> +                size: ::core::mem::size_of::<$type>(),
>                   ..<$base as $crate::vmstate::VMState>::BASE
>               };
>               const VARRAY_FLAG: $crate::bindings::VMStateFlags = <$base as $crate::vmstate::VMState>::VARRAY_FLAG;
> @@ -282,6 +282,7 @@ unsafe impl<$base> $crate::vmstate::VMState for $type where $base: $crate::vmsta
>   impl_vmstate_transparent!(std::cell::UnsafeCell<T> where T: VMState);
>   impl_vmstate_transparent!(std::pin::Pin<T> where T: VMState);
>   impl_vmstate_transparent!(common::Opaque<T> where T: VMState);
> +impl_vmstate_transparent!(std::mem::ManuallyDrop<T> where T: VMState);
>   
>   #[macro_export]
>   macro_rules! impl_vmstate_bitsized {
> diff --git a/rust/qom/src/qom.rs b/rust/qom/src/qom.rs
> index 5808051cd77..84455cea79b 100644
> --- a/rust/qom/src/qom.rs
> +++ b/rust/qom/src/qom.rs
> @@ -102,7 +102,7 @@
>   };
>   
>   use common::Opaque;
> -use migration::impl_vmstate_pointer;
> +use migration::{impl_vmstate_pointer, impl_vmstate_transparent};
>   
>   use crate::bindings::{
>       self, object_class_dynamic_cast, object_dynamic_cast, object_get_class, object_get_typename,
> @@ -182,6 +182,7 @@ fn as_ref(&self) -> &$parent {
>   #[derive(Debug)]
>   #[repr(transparent)]
>   pub struct ParentField<T: ObjectType>(std::mem::ManuallyDrop<T>);
> +impl_vmstate_transparent!(ParentField<T> where T: VMState + ObjectType);
>   
>   impl<T: ObjectType> Deref for ParentField<T> {
>       type Target = T;