vfio: Introduce a vfio_uninit_group_dev() API call

This pairs with vfio_init_group_dev() and allows undoing any state that is
stored in the vfio_device unrelated to registration. Add appropriately
placed calls to all the drivers.

The following patch will use this to add pre-registration state for the
device set.

Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/3-v4-9ea22c5e6afb+1adf-vfio_reflck_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index 8b26fec..37cc906 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -718,8 +718,8 @@ static int mtty_probe(struct mdev_device *mdev)
 
 	mdev_state = kzalloc(sizeof(struct mdev_state), GFP_KERNEL);
 	if (mdev_state == NULL) {
-		atomic_add(nr_ports, &mdev_avail_ports);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto err_nr_ports;
 	}
 
 	vfio_init_group_dev(&mdev_state->vdev, &mdev->dev, &mtty_dev_ops);
@@ -732,9 +732,8 @@ static int mtty_probe(struct mdev_device *mdev)
 	mdev_state->vconfig = kzalloc(MTTY_CONFIG_SPACE_SIZE, GFP_KERNEL);
 
 	if (mdev_state->vconfig == NULL) {
-		kfree(mdev_state);
-		atomic_add(nr_ports, &mdev_avail_ports);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto err_state;
 	}
 
 	mutex_init(&mdev_state->ops_lock);
@@ -743,14 +742,19 @@ static int mtty_probe(struct mdev_device *mdev)
 	mtty_create_config_space(mdev_state);
 
 	ret = vfio_register_group_dev(&mdev_state->vdev);
-	if (ret) {
-		kfree(mdev_state);
-		atomic_add(nr_ports, &mdev_avail_ports);
-		return ret;
-	}
-
+	if (ret)
+		goto err_vconfig;
 	dev_set_drvdata(&mdev->dev, mdev_state);
 	return 0;
+
+err_vconfig:
+	kfree(mdev_state->vconfig);
+err_state:
+	vfio_uninit_group_dev(&mdev_state->vdev);
+	kfree(mdev_state);
+err_nr_ports:
+	atomic_add(nr_ports, &mdev_avail_ports);
+	return ret;
 }
 
 static void mtty_remove(struct mdev_device *mdev)
@@ -761,6 +765,7 @@ static void mtty_remove(struct mdev_device *mdev)
 	vfio_unregister_group_dev(&mdev_state->vdev);
 
 	kfree(mdev_state->vconfig);
+	vfio_uninit_group_dev(&mdev_state->vdev);
 	kfree(mdev_state);
 	atomic_add(nr_ports, &mdev_avail_ports);
 }