vfio-ccw: fence off transport mode

BugLink: http://bugs.launchpad.net/bugs/1786352
[ 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@linux.vnet.ibm.com>
Acked-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index e96b85579f21bdc791add2351449daf9dbc833db..3c800642134e4330d62bb8c0053df62618840ff3 100644 (file)
--- 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_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)