[PATCH v3 4/8] vfio: ccw: Only accept SSCH as an IO request

[Pierre Morel]

This patch simplifies the IO request handling to handle the only
implemented request: SSCH.
Other requests are invalid and get a return value of -ENOTSUP
as before.

Signed-off-by: Pierre Morel <pmo...@linux.ibm.com>
---
 drivers/s390/cio/vfio_ccw_fsm.c | 55 ++++++++++++++++-------------------------
 drivers/s390/cio/vfio_ccw_ops.c | 15 ++++++-----
 2 files changed, 28 insertions(+), 42 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index 94bf151..e672d14 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -122,50 +122,37 @@ 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 private->state;
-       } else if (scsw->cmd.fctl & SCSW_FCTL_HALT_FUNC) {
-               /* XXX: Handle halt. */
+       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;
-       } else if (scsw->cmd.fctl & SCSW_FCTL_CLEAR_FUNC) {
-               /* XXX: Handle clear. */
-               io_region->ret_code = -EOPNOTSUPP;
+       }
+       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 private->state;
+
 err_out:
        return VFIO_CCW_STATE_IDLE;
 }
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 41eeb57..af05932 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -188,25 +188,24 @@ 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;
+       if (scsw->cmd.fctl & SCSW_FCTL_START_FUNC)
+               vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ);
+       else
+               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)
-- 
2.7.4