virtio-9p: use aliases instead of duplicate qdev properties

virtio-9p-pci all duplicate the qdev properties of their
V9fsState child. This approach does not work well with
string or pointer properties since we must be careful
about leaking or double-freeing them.

Use the QOM alias property to forward property accesses to the
V9fsState child.  This way no duplication is necessary.
Signed-off-by: NGonglei <arei.gonglei@huawei.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/virtio/virtio-pci.c

@@ -926,7 +926,6 @@ static Property virtio_9p_pci_properties[] = {
     DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
                     VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
     DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
-    DEFINE_VIRTIO_9P_PROPERTIES(V9fsPCIState, vdev.fsconf),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -950,6 +949,7 @@ static void virtio_9p_pci_instance_init(Object *obj)
     V9fsPCIState *dev = VIRTIO_9P_PCI(obj);
     object_initialize(&dev->vdev, sizeof(dev->vdev), TYPE_VIRTIO_9P);
     object_property_add_child(obj, "virtio-backend", OBJECT(&dev->vdev), NULL);
+    qdev_alias_all_properties(DEVICE(&dev->vdev), obj);
 }
 
 static const TypeInfo virtio_9p_pci_info = {