[PATCH v3 2/6] vfio: ccw: Rework subchannel state on setup

[Pierre Morel <pmorel@linux.ibm.com>]

The subchannel enablement and the according setting to the
VFIO_CCW_STATE_STANDBY state should only be done when all
parts of the VFIO mediated device have been initialized
i.e. after the mediated device has been successfully opened.

Let's stay in VFIO_CCW_STATE_NOT_OPER until the mediated
device has been opened and set the VFIO_CCW_STATE_STANDBY
on a successful open.

On release the state is set back to VFIO_CCW_STATE_NOT_OPER
by vfio_ccw_sch_quiesce().

When the mediated device is closed,  disable the sub channel
by calling vfio_ccw_sch_quiesce().

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 drivers/s390/cio/vfio_ccw_async.c   | 11 +++++++++++
 drivers/s390/cio/vfio_ccw_drv.c     | 10 +---------
 drivers/s390/cio/vfio_ccw_ops.c     | 27 +++++++++++++++++++++------
 drivers/s390/cio/vfio_ccw_private.h |  1 +
 4 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_async.c b/drivers/s390/cio/vfio_ccw_async.c
index 8c7f51d..033574e 100644
--- a/drivers/s390/cio/vfio_ccw_async.c
+++ b/drivers/s390/cio/vfio_ccw_async.c
@@ -76,6 +76,17 @@ const struct vfio_ccw_regops vfio_ccw_async_region_ops = {
 	.release = vfio_ccw_async_region_release,
 };
 
+void vfio_ccw_unregister_async_dev_regions(struct vfio_ccw_private *private)
+{
+	int i;
+
+	for (i = 0; i < private->num_regions; i++)
+		private->region[i].ops->release(private, &private->region[i]);
+	private->num_regions = 0;
+	kfree(private->region);
+	private->region = NULL;
+}
+
 int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private)
 {
 	return vfio_ccw_register_dev_region(private,
diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index bce7fed..d3527b6 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -133,26 +133,18 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
 	private->sch = sch;
 	dev_set_drvdata(&sch->dev, private);
 
-	spin_lock_irq(sch->lock);
 	private->state = VFIO_CCW_STATE_NOT_OPER;
 	sch->isc = VFIO_CCW_ISC;
-	ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
-	spin_unlock_irq(sch->lock);
-	if (ret)
-		goto out_free;
 
 	INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo);
 	atomic_set(&private->avail, 1);
-	private->state = VFIO_CCW_STATE_STANDBY;
 
 	ret = vfio_ccw_mdev_reg(sch);
 	if (ret)
-		goto out_disable;
+		goto out_free;
 
 	return 0;
 
-out_disable:
-	cio_disable_subchannel(sch);
 out_free:
 	dev_set_drvdata(&sch->dev, NULL);
 	if (private->cmd_region)
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 0e1f7f7b..cc7d46a 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -113,14 +113,11 @@ 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;
+	private->state = VFIO_CCW_STATE_NOT_OPER;
 
 	return 0;
 }
@@ -148,6 +145,7 @@ static int vfio_ccw_mdev_open(struct mdev_device *mdev)
 	struct vfio_ccw_private *private =
 		dev_get_drvdata(mdev_parent_dev(mdev));
 	unsigned long events = VFIO_IOMMU_NOTIFY_DMA_UNMAP;
+	struct subchannel *sch = private->sch;
 	int ret;
 
 	private->nb.notifier_call = vfio_ccw_mdev_notifier;
@@ -159,8 +157,24 @@ static int vfio_ccw_mdev_open(struct mdev_device *mdev)
 
 	ret = vfio_ccw_register_async_dev_regions(private);
 	if (ret)
-		vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
-					 &private->nb);
+		goto err_regions;
+
+	spin_lock_irq(private->sch->lock);
+	ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
+	if (ret)
+		goto err_enable;
+
+	private->state = VFIO_CCW_STATE_STANDBY;
+	spin_unlock_irq(sch->lock);
+	return 0;
+
+err_enable:
+	spin_unlock_irq(sch->lock);
+	vfio_ccw_unregister_async_dev_regions(private);
+
+err_regions:
+	vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
+				 &private->nb);
 	return ret;
 }
 
@@ -170,6 +184,7 @@ static void vfio_ccw_mdev_release(struct mdev_device *mdev)
 		dev_get_drvdata(mdev_parent_dev(mdev));
 	int i;
 
+	vfio_ccw_sch_quiesce(private->sch);
 	vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
 				 &private->nb);
 
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index 1a41a14..5d799b7 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -54,6 +54,7 @@ int vfio_ccw_register_dev_region(struct vfio_ccw_private *private,
 				 size_t size, u32 flags, void *data);
 
 int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private);
+void vfio_ccw_unregister_async_dev_regions(struct vfio_ccw_private *private);
 
 /**
  * struct vfio_ccw_private
-- 
2.7.4