The write callback uses the a memory cell of the io_region
as the instruction to proceed.

Since we currently ever used only one instruction, SSCH,
let's state that we can only handle one instruction at a time
- by using a switch/case
- by changing the name of the event to VFIO_CCW_EVENT_SSCH_REQ

Signed-off-by: Pierre Morel <pmo...@linux.vnet.ibm.com>
---
 drivers/s390/cio/vfio_ccw_fsm.c     | 67 ++++++++++++-------------------------
 drivers/s390/cio/vfio_ccw_ops.c     | 16 +++++----
 drivers/s390/cio/vfio_ccw_private.h |  2 +-
 3 files changed, 31 insertions(+), 54 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index 2bc4be66..86dab8c 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -19,14 +19,10 @@ static int fsm_io_helper(struct vfio_ccw_private *private)
        union orb *orb;
        int ccode;
        __u8 lpm;
-       unsigned long flags;
        int ret;
 
        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);
 
        /* Issue "Start Subchannel" */
@@ -61,7 +57,6 @@ static int fsm_io_helper(struct vfio_ccw_private *private)
        default:
                ret = ccode;
        }
-       spin_unlock_irqrestore(sch->lock, flags);
        return ret;
 }
 
@@ -122,50 +117,30 @@ static int fsm_io_request(struct vfio_ccw_private 
*private,
                           enum vfio_ccw_event event)
 {
        union orb *orb;
-       union scsw *scsw = &private->scsw;
        struct ccw_io_region *io_region = &private->io_region;
        struct mdev_device *mdev = private->mdev;
 
        private->state = VFIO_CCW_STATE_BOXED;
 
-       memcpy(scsw, io_region->scsw_area, sizeof(*scsw));
-
-       if (scsw->cmd.fctl & SCSW_FCTL_START_FUNC) {
-               orb = (union orb *)io_region->orb_area;
-
-               /* Don't try to build a cp if transport mode is specified. */
-               if (orb->tm.b) {
-                       io_region->ret_code = -EOPNOTSUPP;
-                       goto err_out;
-               }
-               io_region->ret_code = cp_init(&private->cp, mdev_dev(mdev),
-                                             orb);
-               if (io_region->ret_code)
-                       goto err_out;
-
-               io_region->ret_code = cp_prefetch(&private->cp);
-               if (io_region->ret_code) {
-                       cp_free(&private->cp);
-                       goto err_out;
-               }
-
-               /* Start channel program and wait for I/O interrupt. */
-               io_region->ret_code = fsm_io_helper(private);
-               if (io_region->ret_code) {
-                       cp_free(&private->cp);
-                       goto err_out;
-               }
-               return;
-       } else if (scsw->cmd.fctl & SCSW_FCTL_HALT_FUNC) {
-               /* XXX: Handle halt. */
-               io_region->ret_code = -EOPNOTSUPP;
+       orb = (union orb *)io_region->orb_area;
+
+       io_region->ret_code = cp_init(&private->cp, mdev_dev(mdev), orb);
+       if (io_region->ret_code)
                goto err_out;
-       } else if (scsw->cmd.fctl & SCSW_FCTL_CLEAR_FUNC) {
-               /* XXX: Handle clear. */
-               io_region->ret_code = -EOPNOTSUPP;
+
+       io_region->ret_code = cp_prefetch(&private->cp);
+       if (io_region->ret_code) {
+               cp_free(&private->cp);
                goto err_out;
        }
 
+       io_region->ret_code = fsm_io_helper(private);
+       if (io_region->ret_code) {
+               cp_free(&private->cp);
+               goto err_out;
+       }
+       return VFIO_CCW_STATE_BUSY;
+
 err_out:
        return VFIO_CCW_STATE_IDLE;
 }
@@ -186,7 +161,7 @@ static int fsm_irq(struct vfio_ccw_private *private,
 
        if (private->io_trigger)
                eventfd_signal(private->io_trigger, 1);
-       return private->state;
+       return VFIO_CCW_STATE_IDLE;
 }
 
 /*
@@ -213,31 +188,31 @@ static int fsm_sch_event(struct vfio_ccw_private *private,
 fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {
        [VFIO_CCW_STATE_NOT_OPER] = {
                [VFIO_CCW_EVENT_NOT_OPER]       = fsm_nop,
-               [VFIO_CCW_EVENT_IO_REQ]         = fsm_io_error,
+               [VFIO_CCW_EVENT_SSCH_REQ]       = fsm_io_error,
                [VFIO_CCW_EVENT_INTERRUPT]      = fsm_disabled_irq,
                [VFIO_CCW_EVENT_SCHIB_CHANGED]  = fsm_nop,
        },
        [VFIO_CCW_STATE_STANDBY] = {
                [VFIO_CCW_EVENT_NOT_OPER]       = fsm_notoper,
-               [VFIO_CCW_EVENT_IO_REQ]         = fsm_io_error,
+               [VFIO_CCW_EVENT_SSCH_REQ]       = fsm_io_error,
                [VFIO_CCW_EVENT_INTERRUPT]      = fsm_irq,
                [VFIO_CCW_EVENT_SCHIB_CHANGED]  = fsm_sch_event,
        },
        [VFIO_CCW_STATE_IDLE] = {
                [VFIO_CCW_EVENT_NOT_OPER]       = fsm_notoper,
-               [VFIO_CCW_EVENT_IO_REQ]         = fsm_io_request,
+               [VFIO_CCW_EVENT_SSCH_REQ]       = fsm_io_request,
                [VFIO_CCW_EVENT_INTERRUPT]      = fsm_irq,
                [VFIO_CCW_EVENT_SCHIB_CHANGED]  = fsm_sch_event,
        },
        [VFIO_CCW_STATE_BOXED] = {
                [VFIO_CCW_EVENT_NOT_OPER]       = fsm_notoper,
-               [VFIO_CCW_EVENT_IO_REQ]         = fsm_io_busy,
+               [VFIO_CCW_EVENT_SSCH_REQ]       = fsm_io_busy,
                [VFIO_CCW_EVENT_INTERRUPT]      = fsm_irq,
                [VFIO_CCW_EVENT_SCHIB_CHANGED]  = fsm_sch_event,
        },
        [VFIO_CCW_STATE_BUSY] = {
                [VFIO_CCW_EVENT_NOT_OPER]       = fsm_notoper,
-               [VFIO_CCW_EVENT_IO_REQ]         = fsm_io_busy,
+               [VFIO_CCW_EVENT_SSCH_REQ]       = fsm_io_busy,
                [VFIO_CCW_EVENT_INTERRUPT]      = fsm_irq,
                [VFIO_CCW_EVENT_SCHIB_CHANGED]  = fsm_sch_event,
        },
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 41eeb57..0206101 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -188,25 +188,27 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device 
*mdev,
 {
        struct vfio_ccw_private *private;
        struct ccw_io_region *region;
+       union scsw *scsw;
 
        if (*ppos + count > sizeof(*region))
                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))
                return -EFAULT;
 
-       vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ);
-       if (region->ret_code != 0) {
-               private->state = VFIO_CCW_STATE_IDLE;
-               return region->ret_code;
+       scsw = (union scsw *) &region->scsw_area;
+       switch (scsw->cmd.fctl) {
+       case SCSW_FCTL_START_FUNC:
+               vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_SSCH_REQ);
+               break;
+       default:
+               return -EOPNOTSUPP;
        }
 
-       return count;
+       return region->ret_code ? region->ret_code : count;
 }
 
 static int vfio_ccw_mdev_get_device_info(struct vfio_device_info *info)
diff --git a/drivers/s390/cio/vfio_ccw_private.h 
b/drivers/s390/cio/vfio_ccw_private.h
index a2be0c9..94fb408 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -76,7 +76,7 @@ enum vfio_ccw_state {
  */
 enum vfio_ccw_event {
        VFIO_CCW_EVENT_NOT_OPER,
-       VFIO_CCW_EVENT_IO_REQ,
+       VFIO_CCW_EVENT_SSCH_REQ,
        VFIO_CCW_EVENT_INTERRUPT,
        VFIO_CCW_EVENT_SCHIB_CHANGED,
        /* last element! */
-- 
2.7.4

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