vfio/mdev: embedd struct mdev_parent in the parent data structure

Simplify mdev_{un}register_device by requiring the caller to pass in
a structure allocate as part of the parent device structure.  This
removes the need for a list of parents and the separate mdev_parent
refcount as we can simplify rely on the reference to the parent device.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Link: https://lore.kernel.org/r/20220923092652.100656-5-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

5 files changed, 11 insertions, 5 deletions

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index e9985c63dc6b..7d105915bd14 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -221,7 +221,8 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
 
 	dev_set_drvdata(&sch->dev, private);
 
-	ret = mdev_register_device(&sch->dev, &vfio_ccw_mdev_driver);
+	ret = mdev_register_parent(&private->parent, &sch->dev,
+				   &vfio_ccw_mdev_driver);
 	if (ret)
 		goto out_free;
 
@@ -240,7 +241,7 @@ static void vfio_ccw_sch_remove(struct subchannel *sch)
 {
 	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
 
-	mdev_unregister_device(&sch->dev);
+	mdev_unregister_parent(&private->parent);
 
 	dev_set_drvdata(&sch->dev, NULL);
 
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 9f8486c0d3d3..9a0e0c5ffb1a 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -11,7 +11,6 @@
  */
 
 #include <linux/vfio.h>
-#include <linux/mdev.h>
 #include <linux/nospec.h>
 #include <linux/slab.h>
 
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index 63d9202b29c7..1a4bfb1b5a80 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -18,6 +18,7 @@
 #include <linux/workqueue.h>
 #include <linux/vfio_ccw.h>
 #include <linux/vfio.h>
+#include <linux/mdev.h>
 #include <asm/crw.h>
 #include <asm/debug.h>
 
@@ -89,6 +90,7 @@ struct vfio_ccw_crw {
  * @io_work: work for deferral process of I/O handling
  * @crw_work: work for deferral process of CRW handling
  * @release_comp: synchronization helper for vfio device release
+ * @parent: parent data structures for mdevs created
  */
 struct vfio_ccw_private {
 	struct vfio_device vdev;
@@ -116,6 +118,8 @@ struct vfio_ccw_private {
 	struct work_struct	crw_work;
 
 	struct completion	release_comp;
+
+	struct mdev_parent	parent;
 } __aligned(8);
 
 int vfio_ccw_sch_quiesce(struct subchannel *sch);
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 161597357a64..724d09a74a8f 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1830,7 +1830,8 @@ int vfio_ap_mdev_register(void)
 	if (ret)
 		return ret;
 
-	ret = mdev_register_device(&matrix_dev->device, &vfio_ap_matrix_driver);
+	ret = mdev_register_parent(&matrix_dev->parent, &matrix_dev->device,
+				   &vfio_ap_matrix_driver);
 	if (ret)
 		goto err_driver;
 	return 0;
@@ -1842,7 +1843,7 @@ err_driver:
 
 void vfio_ap_mdev_unregister(void)
 {
-	mdev_unregister_device(&matrix_dev->device);
+	mdev_unregister_parent(&matrix_dev->parent);
 	mdev_unregister_driver(&vfio_ap_matrix_driver);
 }
 
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 163eeaaf24ce..35165730f517 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -52,6 +52,7 @@ struct ap_matrix_dev {
 	struct mutex mdevs_lock; /* serializes access to each ap_matrix_mdev */
 	struct ap_driver  *vfio_ap_drv;
 	struct mutex guests_lock; /* serializes access to each KVM guest */
+	struct mdev_parent parent;
 };
 
 extern struct ap_matrix_dev *matrix_dev;