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Avoid some races in vfio-ccw request handling.

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Merge tag 'vfio-ccw-20210520' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/vfio-ccw into fixes

Avoid some races in vfio-ccw request handling.

* tag 'vfio-ccw-20210520' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/vfio-ccw:
  vfio-ccw: Serialize FSM IDLE state with I/O completion
  vfio-ccw: Reset FSM state to IDLE inside FSM
  vfio-ccw: Check initialized flag in cp_init()

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2021-05-26 23:46:34 +02:00
commit ffa99c436a
4 changed files with 15 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
drivers/s390/cio/vfio_ccw_cp.c
View file

@ -638,6 +638,10 @@ int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb)
static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 1);
int ret;
/* this is an error in the caller */
if (cp->initialized)
return -EBUSY;
/*
* We only support prefetching the channel program. We assume all channel
* programs executed by supported guests likewise support prefetching.

12
drivers/s390/cio/vfio_ccw_drv.c
View file

@ -86,6 +86,7 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work)
struct vfio_ccw_private *private;
struct irb *irb;
bool is_final;
bool cp_is_finished = false;
private = container_of(work, struct vfio_ccw_private, io_work);
irb = &private->irb;
@ -94,14 +95,21 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work)
(SCSW_ACTL_DEVACT | SCSW_ACTL_SCHACT));
if (scsw_is_solicited(&irb->scsw)) {
cp_update_scsw(&private->cp, &irb->scsw);
if (is_final && private->state == VFIO_CCW_STATE_CP_PENDING)
if (is_final && private->state == VFIO_CCW_STATE_CP_PENDING) {
cp_free(&private->cp);
cp_is_finished = true;
}
}
mutex_lock(&private->io_mutex);
memcpy(private->io_region->irb_area, irb, sizeof(*irb));
mutex_unlock(&private->io_mutex);
if (private->mdev && is_final)
/*
* 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.
*/
if (private->mdev && cp_is_finished)
private->state = VFIO_CCW_STATE_IDLE;
if (private->io_trigger)

1
drivers/s390/cio/vfio_ccw_fsm.c
View file

@ -318,6 +318,7 @@ static void fsm_io_request(struct vfio_ccw_private *private,
}
err_out:
private->state = VFIO_CCW_STATE_IDLE;
trace_vfio_ccw_fsm_io_request(scsw->cmd.fctl, schid,
io_region->ret_code, errstr);
}

2
drivers/s390/cio/vfio_ccw_ops.c
View file

@ -279,8 +279,6 @@ static ssize_t vfio_ccw_mdev_write_io_region(struct vfio_ccw_private *private,
}
vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ);
if (region->ret_code != 0)
private->state = VFIO_CCW_STATE_IDLE;
ret = (region->ret_code != 0) ? region->ret_code : count;
out_unlock: