vfio: check vfio_register_iommu_driver() return value

As vfio_register_iommu_driver() can fail, we should check the return value.
Signed-off-by: Bo Liu <liubo03@inspur.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Link: https://lore.kernel.org/r/20220622045651.5416-1-liubo03@inspur.comSigned-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/vfio.c

@@ -2156,13 +2156,17 @@ static int __init vfio_init(void)
 	if (ret)
 		goto err_alloc_chrdev;
 
-	pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
-
 #ifdef CONFIG_VFIO_NOIOMMU
-	vfio_register_iommu_driver(&vfio_noiommu_ops);
+	ret = vfio_register_iommu_driver(&vfio_noiommu_ops);
 #endif
+	if (ret)
+		goto err_driver_register;
+
+	pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
 	return 0;
 
+err_driver_register:
+	unregister_chrdev_region(vfio.group_devt, MINORMASK + 1);
 err_alloc_chrdev:
 	class_destroy(vfio.class);
 	vfio.class = NULL;