vhost-user: Interface for migration state transfer

Add the interface for transferring the back-end's state during migration
as defined previously in vhost-user.rst.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
Message-Id: <20231016134243.68248-6-hreitz@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 9c9ae7109e..4db9dbfd64 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -2159,3 +2159,40 @@ int vhost_reset_device(struct vhost_dev *hdev)
 
     return -ENOSYS;
 }
+
+bool vhost_supports_device_state(struct vhost_dev *dev)
+{
+    if (dev->vhost_ops->vhost_supports_device_state) {
+        return dev->vhost_ops->vhost_supports_device_state(dev);
+    }
+
+    return false;
+}
+
+int vhost_set_device_state_fd(struct vhost_dev *dev,
+                              VhostDeviceStateDirection direction,
+                              VhostDeviceStatePhase phase,
+                              int fd,
+                              int *reply_fd,
+                              Error **errp)
+{
+    if (dev->vhost_ops->vhost_set_device_state_fd) {
+        return dev->vhost_ops->vhost_set_device_state_fd(dev, direction, phase,
+                                                         fd, reply_fd, errp);
+    }
+
+    error_setg(errp,
+               "vhost transport does not support migration state transfer");
+    return -ENOSYS;
+}
+
+int vhost_check_device_state(struct vhost_dev *dev, Error **errp)
+{
+    if (dev->vhost_ops->vhost_check_device_state) {
+        return dev->vhost_ops->vhost_check_device_state(dev, errp);
+    }
+
+    error_setg(errp,
+               "vhost transport does not support migration state transfer");
+    return -ENOSYS;
+}