vfio/ccw: Do not change FSM state in subchannel event

[ Upstream commit b0e6895db0a7ef594ea88f95803c2b15e90f1fc3 ]

The routine vfio_ccw_sch_event() is tasked with handling subchannel events,
specifically machine checks, on behalf of vfio-ccw. It correctly calls
cio_update_schib(), and if that fails (meaning the subchannel is gone)
it makes an FSM event call to mark the subchannel Not Operational.

If that worked, however, then it decides that if the FSM state was already
Not Operational (implying the subchannel just came back), then it should
simply change the FSM to partially- or fully-open.

Remove this trickery, since a subchannel returning will require more
probing than simply "oh all is well again" to ensure it works correctly.

Fixes: 14c50d87bb535 ("vfio: ccw: introduce a finite state machine")
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20220707135737.720765-4-farman@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index 76099bcb765b457c4b06419f110776599e62b6c1..b9091e22ca5722be629fa860b21e472b4d612d4b 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -287,19 +287,11 @@ static int vfio_ccw_sch_event(struct subchannel *sch, int process)
        if (work_pending(&sch->todo_work))
                goto out_unlock;
 
-       if (cio_update_schib(sch)) {
-               vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_NOT_OPER);
-               rc = 0;
-               goto out_unlock;
-       }
-
-       private = dev_get_drvdata(&sch->dev);
-       if (private->state == VFIO_CCW_STATE_NOT_OPER) {
-               private->state = private->mdev ? VFIO_CCW_STATE_IDLE :
-                                VFIO_CCW_STATE_STANDBY;
-       }
        rc = 0;
 
+       if (cio_update_schib(sch))
+               vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_NOT_OPER);
+
 out_unlock:
        spin_unlock_irqrestore(sch->lock, flags);