vfio: ccw: introduce a finite state machine
The current implementation doesn't check if the subchannel is in a
proper device state when handling an event. Let's introduce
a finite state machine to manage the state/event change.
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20170317031743.40128-14-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index d754d3d..b2e6154 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -35,7 +35,11 @@ static int vfio_ccw_mdev_reset(struct mdev_device *mdev)
if (ret)
return ret;
- return cio_enable_subchannel(sch, (u32)(unsigned long)sch);
+ ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
+ if (!ret)
+ private->state = VFIO_CCW_STATE_IDLE;
+
+ return ret;
}
static int vfio_ccw_mdev_notifier(struct notifier_block *nb,
@@ -112,10 +116,14 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
struct vfio_ccw_private *private =
dev_get_drvdata(mdev_parent_dev(mdev));
+ if (private->state == VFIO_CCW_STATE_NOT_OPER)
+ return -ENODEV;
+
if (atomic_dec_if_positive(&private->avail) < 0)
return -EPERM;
private->mdev = mdev;
+ private->state = VFIO_CCW_STATE_IDLE;
return 0;
}
@@ -126,10 +134,20 @@ static int vfio_ccw_mdev_remove(struct mdev_device *mdev)
dev_get_drvdata(mdev_parent_dev(mdev));
int ret;
+ if (!private)
+ goto out;
+
+ if ((private->state == VFIO_CCW_STATE_NOT_OPER) ||
+ (private->state == VFIO_CCW_STATE_STANDBY))
+ goto out;
+
ret = vfio_ccw_mdev_reset(mdev);
if (ret)
return ret;
+ private->state = VFIO_CCW_STATE_STANDBY;
+
+out:
private->mdev = NULL;
atomic_inc(&private->avail);
@@ -193,14 +211,18 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev,
private = dev_get_drvdata(mdev_parent_dev(mdev));
if (!private)
return -ENODEV;
+ if (private->state != VFIO_CCW_STATE_IDLE)
+ return -EACCES;
region = &private->io_region;
if (copy_from_user((void *)region + *ppos, buf, count))
return -EFAULT;
- region->ret_code = vfio_ccw_sch_cmd_request(private);
- if (region->ret_code != 0)
+ 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;
+ }
return count;
}