rust/vmstate: Re-implement VMState trait for timer binding

At present, Rust side has a timer binding "timer::Timer", so the vmstate
for timer should base on that binding instead of the raw
"binding::QEMUTimer".

It's possible to apply impl_vmstate_transparent for cell::Opaque and
then impl_vmstate_forward for timer::Timer. But binding::QEMUTimer
shouldn't be used directly, so that vmstate for such raw timer type is
useless.

Thus, apply impl_vmstate_scalar for timer::Timer. And since Opaque<> is
useful, apply impl_vmstate_transparent for cell::Opaque as well.

Signed-off-by: Zhao Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Paolo Bonzini <[email protected]>

Author: trueptolemy

rust/qemu-api/src/vmstate.rs

@@ -27,12 +27,7 @@
 use core::{marker::PhantomData, mem, ptr::NonNull};
 
 pub use crate::bindings::{VMStateDescription, VMStateField};
-use crate::{
-    bindings::{self, VMStateFlags},
-    prelude::*,
-    qom::Owned,
-    zeroable::Zeroable,
-};
+use crate::{bindings::VMStateFlags, prelude::*, qom::Owned, zeroable::Zeroable};
 
 /// This macro is used to call a function with a generic argument bound
 /// to the type of a field.  The function must take a
@@ -344,6 +339,7 @@ impl_vmstate_transparent!(std::cell::UnsafeCell<T> where T: VMState);
 impl_vmstate_transparent!(std::pin::Pin<T> where T: VMState);
 impl_vmstate_transparent!(crate::cell::BqlCell<T> where T: VMState);
 impl_vmstate_transparent!(crate::cell::BqlRefCell<T> where T: VMState);
+impl_vmstate_transparent!(crate::cell::Opaque<T> where T: VMState);
 
 #[macro_export]
 macro_rules! impl_vmstate_bitsized {
@@ -390,7 +386,7 @@ impl_vmstate_scalar!(vmstate_info_uint8, u8, VMS_VARRAY_UINT8);
 impl_vmstate_scalar!(vmstate_info_uint16, u16, VMS_VARRAY_UINT16);
 impl_vmstate_scalar!(vmstate_info_uint32, u32, VMS_VARRAY_UINT32);
 impl_vmstate_scalar!(vmstate_info_uint64, u64);
-impl_vmstate_scalar!(vmstate_info_timer, bindings::QEMUTimer);
+impl_vmstate_scalar!(vmstate_info_timer, crate::timer::Timer);
 
 // Pointer types using the underlying type's VMState plus VMS_POINTER
 // Note that references are not supported, though references to cells