system/runstate: add VM state change cb with return value

This patch adds the new VM state change cb type `VMChangeStateHandlerWithRet`,
which has return value for `VMChangeStateEntry`.

Thus, we can register a new VM state change cb with return value for device.
Note that `VMChangeStateHandler` and `VMChangeStateHandlerWithRet` are mutually
exclusive and cannot be provided at the same time.

This patch is the pre patch for 'vhost-user: return failure if backend crashes
when live migration', which makes the live migration aware of the loss of
connection with the vhost-user backend and aborts the live migration.

Virtio device will use VMChangeStateHandlerWithRet.

Signed-off-by: Haoqian He <haoqian.he@smartx.com>
Message-Id: <20250416024729.3289157-2-haoqian.he@smartx.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 1dceab1b19..b76697bd1a 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -1016,7 +1016,7 @@ static int vfio_migration_init(VFIODevice *vbasedev)
                      vfio_vmstate_change_prepare :
                      NULL;
     migration->vm_state = qdev_add_vm_change_state_handler_full(
-        vbasedev->dev, vfio_vmstate_change, prepare_cb, vbasedev);
+        vbasedev->dev, vfio_vmstate_change, prepare_cb, NULL, vbasedev);
     migration_add_notifier(&migration->migration_state,
                            vfio_migration_state_notifier);