diff options
author | Cornelia Huck <cohuck@redhat.com> | 2019-01-29 16:13:57 +0100 |
---|---|---|
committer | Cornelia Huck <cohuck@redhat.com> | 2019-04-24 14:18:51 +0200 |
commit | 690f6a1581c7c08e85451f62bcbfe40f29072842 (patch) | |
tree | 27971d432e7baa0f7d74a182575fda241c704a75 | |
parent | 71189f263f8a3db7b72ca75be14e7309375e8707 (diff) |
vfio-ccw: rework ssch state handling
The flow for processing ssch requests can be improved by splitting
the BUSY state:
- CP_PROCESSING: We reject any user space requests while we are in
the process of translating a channel program and submitting it to
the hardware. Use -EAGAIN to signal user space that it should
retry the request.
- CP_PENDING: We have successfully submitted a request with ssch and
are now expecting an interrupt. As we can't handle more than one
channel program being processed, reject any further requests with
-EBUSY. A final interrupt will move us out of this state.
By making this a separate state, we make it possible to issue a
halt or a clear while we're still waiting for the final interrupt
for the ssch (in a follow-on patch).
It also makes a lot of sense not to preemptively filter out writes to
the io_region if we're in an incorrect state: the state machine will
handle this correctly.
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
-rw-r--r-- | drivers/s390/cio/vfio_ccw_fsm.c | 19 | ||||
-rw-r--r-- | drivers/s390/cio/vfio_ccw_ops.c | 2 | ||||
-rw-r--r-- | drivers/s390/cio/vfio_ccw_private.h | 3 |
3 files changed, 16 insertions, 8 deletions
diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c index e7c9877c9f1e..b4a141fbd1a8 100644 --- a/drivers/s390/cio/vfio_ccw_fsm.c +++ b/drivers/s390/cio/vfio_ccw_fsm.c @@ -28,7 +28,6 @@ static int fsm_io_helper(struct vfio_ccw_private *private) sch = private->sch; spin_lock_irqsave(sch->lock, flags); - private->state = VFIO_CCW_STATE_BUSY; orb = cp_get_orb(&private->cp, (u32)(addr_t)sch, sch->lpm); if (!orb) { @@ -46,6 +45,7 @@ static int fsm_io_helper(struct vfio_ccw_private *private) */ sch->schib.scsw.cmd.actl |= SCSW_ACTL_START_PEND; ret = 0; + private->state = VFIO_CCW_STATE_CP_PENDING; break; case 1: /* Status pending */ case 2: /* Busy */ @@ -107,6 +107,12 @@ static void fsm_io_busy(struct vfio_ccw_private *private, private->io_region->ret_code = -EBUSY; } +static void fsm_io_retry(struct vfio_ccw_private *private, + enum vfio_ccw_event event) +{ + private->io_region->ret_code = -EAGAIN; +} + static void fsm_disabled_irq(struct vfio_ccw_private *private, enum vfio_ccw_event event) { @@ -135,8 +141,7 @@ static void fsm_io_request(struct vfio_ccw_private *private, struct mdev_device *mdev = private->mdev; char *errstr = "request"; - private->state = VFIO_CCW_STATE_BUSY; - + private->state = VFIO_CCW_STATE_CP_PROCESSING; memcpy(scsw, io_region->scsw_area, sizeof(*scsw)); if (scsw->cmd.fctl & SCSW_FCTL_START_FUNC) { @@ -181,7 +186,6 @@ static void fsm_io_request(struct vfio_ccw_private *private, } err_out: - private->state = VFIO_CCW_STATE_IDLE; trace_vfio_ccw_io_fctl(scsw->cmd.fctl, get_schid(private), io_region->ret_code, errstr); } @@ -221,7 +225,12 @@ fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = { [VFIO_CCW_EVENT_IO_REQ] = fsm_io_request, [VFIO_CCW_EVENT_INTERRUPT] = fsm_irq, }, - [VFIO_CCW_STATE_BUSY] = { + [VFIO_CCW_STATE_CP_PROCESSING] = { + [VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper, + [VFIO_CCW_EVENT_IO_REQ] = fsm_io_retry, + [VFIO_CCW_EVENT_INTERRUPT] = fsm_irq, + }, + [VFIO_CCW_STATE_CP_PENDING] = { [VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper, [VFIO_CCW_EVENT_IO_REQ] = fsm_io_busy, [VFIO_CCW_EVENT_INTERRUPT] = fsm_irq, diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c index f673e106c041..3fdcc6dfe0bf 100644 --- a/drivers/s390/cio/vfio_ccw_ops.c +++ b/drivers/s390/cio/vfio_ccw_ops.c @@ -193,8 +193,6 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev, return -EINVAL; private = dev_get_drvdata(mdev_parent_dev(mdev)); - if (private->state != VFIO_CCW_STATE_IDLE) - return -EACCES; region = private->io_region; if (copy_from_user((void *)region + *ppos, buf, count)) diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h index 08e9a7dc9176..50c52efb4fcb 100644 --- a/drivers/s390/cio/vfio_ccw_private.h +++ b/drivers/s390/cio/vfio_ccw_private.h @@ -63,7 +63,8 @@ enum vfio_ccw_state { VFIO_CCW_STATE_NOT_OPER, VFIO_CCW_STATE_STANDBY, VFIO_CCW_STATE_IDLE, - VFIO_CCW_STATE_BUSY, + VFIO_CCW_STATE_CP_PROCESSING, + VFIO_CCW_STATE_CP_PENDING, /* last element! */ NR_VFIO_CCW_STATES }; |