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 <manos.pitsidianakis@linaro.org>
Link: https://lore.kernel.org/r/20250711-rust-qdev-properties-v3-1-e198624416fb@linaro.org
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/rust/hw/timer/hpet/src/device.rs b/rust/hw/timer/hpet/src/device.rs
index acf7251029..01d5a0dd70 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)
     }