About the instance_finalize callback in VFIO PCI

[Yang Zhong]

Hello Alex and Paolo,

There is one instance_finalize callback definition in hw/vfio/pci.c, but
i find this callback(vfio_instance_finalize()) never be called during the
VM shutdown with close VM or "init 0" command in guest.

The Qemu related command:
   ......
   -device vfio-pci,host=d9:00.0
   ......

static const TypeInfo vfio_pci_dev_info = {
    .name = TYPE_VFIO_PCI,
    .parent = TYPE_PCI_DEVICE,
    .instance_size = sizeof(VFIOPCIDevice),
    .class_init = vfio_pci_dev_class_init,
    .instance_init = vfio_instance_init,
    .instance_finalize = vfio_instance_finalize,
    .interfaces = (InterfaceInfo[]) {
        { INTERFACE_PCIE_DEVICE },
        { INTERFACE_CONVENTIONAL_PCI_DEVICE },
        { }
    },
};

If my test method is wrong, would you please tell me how to trigger to
this callback when VM shutdown? thanks.

By the way, i also debugged other instance_finalize callback functions,
if my understanding is right, all instance_finalize callback should be
called from object_unref(object) from qemu_cleanup(void) in
./softmmu/runstate.c. But there is no VFIO related object_unref() call in
this cleanup function, So the instance_finalize callback in vfio pci
should be useless? thanks!

Regards,
Yang