vfio/ccw: create a parent struct

Move the stuff associated with the mdev parent (and thus the
subchannel struct) into its own struct, and leave the rest in
the existing private structure.

The subchannel will point to the parent, and the parent will point
to the private, for the areas where one or both are needed. Further
separation of these structs will follow.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20221104142007.1314999-2-farman@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 80 insertions, 18 deletions

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index 7f5402fe857a..444b32047397 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -36,10 +36,19 @@ debug_info_t *vfio_ccw_debug_trace_id;
  */
 int vfio_ccw_sch_quiesce(struct subchannel *sch)
 {
-	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_parent *parent = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_private *private = dev_get_drvdata(&parent->dev);
 	DECLARE_COMPLETION_ONSTACK(completion);
 	int iretry, ret = 0;
 
+	/*
+	 * Probably an impossible situation, after being called through
+	 * FSM callbacks. But in the event it did, register a warning
+	 * and return as if things were fine.
+	 */
+	if (WARN_ON(!private))
+		return 0;
+
 	iretry = 255;
 	do {
 
@@ -121,7 +130,23 @@ static void vfio_ccw_crw_todo(struct work_struct *work)
  */
 static void vfio_ccw_sch_irq(struct subchannel *sch)
 {
-	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_parent *parent = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_private *private = dev_get_drvdata(&parent->dev);
+
+	/*
+	 * The subchannel should still be disabled at this point,
+	 * so an interrupt would be quite surprising. As with an
+	 * interrupt while the FSM is closed, let's attempt to
+	 * disable the subchannel again.
+	 */
+	if (!private) {
+		VFIO_CCW_MSG_EVENT(2, "sch %x.%x.%04x: unexpected interrupt\n",
+				   sch->schid.cssid, sch->schid.ssid,
+				   sch->schid.sch_no);
+
+		cio_disable_subchannel(sch);
+		return;
+	}
 
 	inc_irq_stat(IRQIO_CIO);
 	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT);
@@ -201,10 +226,19 @@ static void vfio_ccw_free_private(struct vfio_ccw_private *private)
 	mutex_destroy(&private->io_mutex);
 	kfree(private);
 }
+
+static void vfio_ccw_free_parent(struct device *dev)
+{
+	struct vfio_ccw_parent *parent = container_of(dev, struct vfio_ccw_parent, dev);
+
+	kfree(parent);
+}
+
 static int vfio_ccw_sch_probe(struct subchannel *sch)
 {
 	struct pmcw *pmcw = &sch->schib.pmcw;
 	struct vfio_ccw_private *private;
+	struct vfio_ccw_parent *parent;
 	int ret = -ENOMEM;
 
 	if (pmcw->qf) {
@@ -213,38 +247,58 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
 		return -ENODEV;
 	}
 
+	parent = kzalloc(sizeof(*parent), GFP_KERNEL);
+	if (!parent)
+		return -ENOMEM;
+
+	dev_set_name(&parent->dev, "parent");
+	parent->dev.parent = &sch->dev;
+	parent->dev.release = &vfio_ccw_free_parent;
+	ret = device_register(&parent->dev);
+	if (ret)
+		goto out_free;
+
 	private = vfio_ccw_alloc_private(sch);
-	if (IS_ERR(private))
+	if (IS_ERR(private)) {
+		device_unregister(&parent->dev);
 		return PTR_ERR(private);
+	}
 
-	dev_set_drvdata(&sch->dev, private);
+	dev_set_drvdata(&sch->dev, parent);
+	dev_set_drvdata(&parent->dev, private);
 
-	private->mdev_type.sysfs_name = "io";
-	private->mdev_type.pretty_name = "I/O subchannel (Non-QDIO)";
-	private->mdev_types[0] = &private->mdev_type;
-	ret = mdev_register_parent(&private->parent, &sch->dev,
+	parent->mdev_type.sysfs_name = "io";
+	parent->mdev_type.pretty_name = "I/O subchannel (Non-QDIO)";
+	parent->mdev_types[0] = &parent->mdev_type;
+	ret = mdev_register_parent(&parent->parent, &sch->dev,
 				   &vfio_ccw_mdev_driver,
-				   private->mdev_types, 1);
+				   parent->mdev_types, 1);
 	if (ret)
-		goto out_free;
+		goto out_unreg;
 
 	VFIO_CCW_MSG_EVENT(4, "bound to subchannel %x.%x.%04x\n",
 			   sch->schid.cssid, sch->schid.ssid,
 			   sch->schid.sch_no);
 	return 0;
 
+out_unreg:
+	device_unregister(&parent->dev);
 out_free:
+	dev_set_drvdata(&parent->dev, NULL);
 	dev_set_drvdata(&sch->dev, NULL);
-	vfio_ccw_free_private(private);
+	if (private)
+		vfio_ccw_free_private(private);
 	return ret;
 }
 
 static void vfio_ccw_sch_remove(struct subchannel *sch)
 {
-	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_parent *parent = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_private *private = dev_get_drvdata(&parent->dev);
 
-	mdev_unregister_parent(&private->parent);
+	mdev_unregister_parent(&parent->parent);
 
+	device_unregister(&parent->dev);
 	dev_set_drvdata(&sch->dev, NULL);
 
 	vfio_ccw_free_private(private);
@@ -256,7 +310,11 @@ static void vfio_ccw_sch_remove(struct subchannel *sch)
 
 static void vfio_ccw_sch_shutdown(struct subchannel *sch)
 {
-	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_parent *parent = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_private *private = dev_get_drvdata(&parent->dev);
+
+	if (WARN_ON(!private))
+		return;
 
 	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_CLOSE);
 	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_NOT_OPER);
@@ -274,7 +332,8 @@ static void vfio_ccw_sch_shutdown(struct subchannel *sch)
  */
 static int vfio_ccw_sch_event(struct subchannel *sch, int process)
 {
-	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_parent *parent = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_private *private = dev_get_drvdata(&parent->dev);
 	unsigned long flags;
 	int rc = -EAGAIN;
 
@@ -287,8 +346,10 @@ static int vfio_ccw_sch_event(struct subchannel *sch, int process)
 
 	rc = 0;
 
-	if (cio_update_schib(sch))
-		vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_NOT_OPER);
+	if (cio_update_schib(sch)) {
+		if (private)
+			vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_NOT_OPER);
+	}
 
 out_unlock:
 	spin_unlock_irqrestore(sch->lock, flags);
@@ -326,7 +387,8 @@ static void vfio_ccw_queue_crw(struct vfio_ccw_private *private,
 static int vfio_ccw_chp_event(struct subchannel *sch,
 			      struct chp_link *link, int event)
 {
-	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_parent *parent = dev_get_drvdata(&sch->dev);
+	struct vfio_ccw_private *private = dev_get_drvdata(&parent->dev);
 	int mask = chp_ssd_get_mask(&sch->ssd_info, link);
 	int retry = 255;