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    Subject[PATCH 5.19 0939/1157] vfio/ccw: Fix FSM state if mdev probe fails
    Date
    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 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;
    }

    --
    2.35.1


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