tests/nodedevmdevctldata/mdevctl-modify.json

   1 {"mdev_type":"vfio_ccw-io","start":"manual"}
   2 {"mdev_type":"vfio_ccw-io","start":"manual","attrs":[{"add_attr_1":"val1"},{"add_attr_2":"val2"}]}
   3 {"mdev_type":"vfio_ccw-io","start":"manual"}
   4 {"mdev_type":"vfio_ccw-io","start":"manual","attrs":[{"add_attr_1":"val1"},{"add_attr_2":"val2"}]}