rust: qdev: add clock creation

Add a Rust version of qdev_init_clock_in, which can be used in
instance_init.  There are a couple differences with the C
version:

- in Rust the object keeps its own reference to the clock (in addition to
  the one embedded in the NamedClockList), and the reference is dropped
  automatically by instance_finalize(); this is encoded in the signature
  of DeviceClassMethods::init_clock_in, which makes the lifetime of the
  clock independent of that of the object it holds.  This goes unnoticed
  in the C version and is due to the existence of aliases.

- also, anything that happens during instance_init uses the pinned_init
  framework to operate on a partially initialized object, and is done
  through class methods (i.e. through DeviceClassMethods rather than
  DeviceMethods) because the device does not exist yet.  Therefore, Rust
  code *must* create clocks from instance_init, which is stricter than C.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2025-01-17 11:21:26 +01:00
parent 66bcc554d2
commit 201ef001dd
4 changed files with 125 additions and 31 deletions

View file

@ -470,11 +470,11 @@ macro_rules! vmstate_clock {
$crate::assert_field_type!(
$struct_name,
$field_name,
core::ptr::NonNull<$crate::bindings::Clock>
$crate::qom::Owned<$crate::bindings::Clock>
);
$crate::offset_of!($struct_name, $field_name)
},
size: ::core::mem::size_of::<*const $crate::bindings::Clock>(),
size: ::core::mem::size_of::<*const $crate::qdev::Clock>(),
flags: VMStateFlags(VMStateFlags::VMS_STRUCT.0 | VMStateFlags::VMS_POINTER.0),
vmsd: unsafe { ::core::ptr::addr_of!($crate::bindings::vmstate_clock) },
..$crate::zeroable::Zeroable::ZERO