[PATCH v3 02/11] vfio/ccw: Fix FSM state if mdev probe fails

Eric Farman
2022-06-30T20:37:18Z

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>
---
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 35055eb94115..179eb614fa5b 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -106,9 +106,10 @@ 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 0e05bff78b8e..9a05dadcbb75 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;
}

--
2.32.0