[PATCH 4.16 218/272] vfio-ccw: fence off transport mode

[Greg Kroah-Hartman]

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Cornelia Huck <cohuck@xxxxxxxxxx>

[ Upstream commit 9851bc77e62499957567e7c39a5beba7d6de6296 ]

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@xxxxxxxxxxxxxxxxxx>
Acked-by: Halil Pasic <pasic@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/s390/cio/vfio_ccw_fsm.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -129,6 +129,11 @@ static void fsm_io_request(struct vfio_c
 	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)