[PATCH 5.18 0867/1095] vfio/ccw: Fix FSM state if mdev probe fails

Greg Kroah-Hartman
2022-08-15T22:39:08Z

From: Eric Farman <farman@linux.ibm.com>

[ Upstream commit f6c876d67e956de8d69349b0ee43bc7277c09e5c ]

The FSM is in STANDBY state when arriving in vfio_ccw_mdev_probe(),
and this routine converts it to IDLE as part of its processing.
The error exit sets it to IDLE (again) but clears the private->mdev
pointer.

The FSM should of course be managing the state itself, but the
correct thing for vfio_ccw_mdev_probe() to do would be to put
the state back the way it found it.

The corresponding check of private->mdev in vfio_ccw_sch_io_todo()
can be removed, since the distinction is unnecessary at this point.

Fixes: 3bf1311f351ef ("vfio/ccw: Convert to use vfio_register_emulated_iommu_dev()")
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20220707135737.720765-3-farman@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/s390/cio/vfio_ccw_drv.c | 5 +++--
drivers/s390/cio/vfio_ccw_ops.c | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index ee182cfb467d..789175221e9a 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -107,9 +107,10 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work)
/*
* Reset to IDLE only if processing of a channel program
* has finished. Do not overwrite a possible processing
- * state if the final interrupt was for HSCH or CSCH.
+ * state if the interrupt was unsolicited, or if the final
+ * interrupt was for HSCH or CSCH.
*/
- if (private->mdev && cp_is_finished)
+ if (cp_is_finished)
private->state = VFIO_CCW_STATE_IDLE;

if (private->io_trigger)
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index d8589afac272..8d76f5b26e2b 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -146,7 +146,7 @@ static int vfio_ccw_mdev_probe(struct mdev_device *mdev)
vfio_uninit_group_dev(&private->vdev);
atomic_inc(&private->avail);
private->mdev = NULL;
- private->state = VFIO_CCW_STATE_IDLE;
+ private->state = VFIO_CCW_STATE_STANDBY;
return ret;
}

--
2.35.1