vfio-ccw: fence off transport mode

vfio-ccw only supports command mode for channel programs, not transport
mode. User space is supposed to already take care of that and pass us
command-mode ORBs only, but better make sure and return an error to
the caller instead of trying to process tcws as ccws.

Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Acked-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index c30420c517b1..ff6963ad6e39 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -124,6 +124,11 @@ static void fsm_io_request(struct vfio_ccw_private *private,
         if (scsw->cmd.fctl & SCSW_FCTL_START_FUNC) {
                 orb = (union orb *)io_region->orb_area;
 
+                /* Don't try to build a cp if transport mode is specified. */
+                if (orb->tm.b) {
+                        io_region->ret_code = -EOPNOTSUPP;
+                        goto err_out;
+                }
                 io_region->ret_code = cp_init(&private->cp, mdev_dev(mdev),
                                               orb);
                 if (io_region->ret_code)