vm-virtio: vhost-user-blk: Add support for reset

If we expect the vhost-user-blk device to be used for booting a VMM
along with the firmware, then need the device to support being reset.

In the vhost-user context, this means the backend needs to be informed
the vrings are disabled and stopped, and the owner needs to be reset
too.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vm-virtio/src/lib.rs

@@ -132,6 +132,8 @@ pub enum ActivateError {
     VhostUserNetSetup(vhost_user::Error),
     /// Failed to setup vhost-user daemon.
     VhostUserBlkSetup(vhost_user::Error),
+    /// Failed to reset vhost-user daemon.
+    VhostUserReset(vhost_user::Error),
 }
 
 pub type ActivateResult = std::result::Result<(), ActivateError>;