Merge tag 'vfio-v3.11' of git://github.com/awilliam/linux-vfio

Pull vfio updates from Alex Williamson:
 "Largely hugepage support for vfio/type1 iommu and surrounding cleanups
  and fixes"

* tag 'vfio-v3.11' of git://github.com/awilliam/linux-vfio:
  vfio/type1: Fix leak on error path
  vfio: Limit group opens
  vfio/type1: Fix missed frees and zero sized removes
  vfio: fix documentation
  vfio: Provide module option to disable vfio_iommu_type1 hugepage support
  vfio: hugepage support for vfio_iommu_type1
  vfio: Convert type1 iommu to use rbtree

Documentation/vfio.txt

@@ -172,12 +172,12 @@ group and can access them as follows:
 	struct vfio_device_info device_info = { .argsz = sizeof(device_info) };
 
 	/* Create a new container */
-	container = open("/dev/vfio/vfio, O_RDWR);
+	container = open("/dev/vfio/vfio", O_RDWR);
 
 	if (ioctl(container, VFIO_GET_API_VERSION) != VFIO_API_VERSION)
 		/* Unknown API version */
 
-	if (!ioctl(container, VFIO_CHECK_EXTENSION, VFIO_X86_IOMMU))
+	if (!ioctl(container, VFIO_CHECK_EXTENSION, VFIO_TYPE1_IOMMU))
 		/* Doesn't support the IOMMU driver we want. */
 
 	/* Open the group */
@@ -193,7 +193,7 @@ group and can access them as follows:
 	ioctl(group, VFIO_GROUP_SET_CONTAINER, &container);
 
 	/* Enable the IOMMU model we want */
-	ioctl(container, VFIO_SET_IOMMU, VFIO_X86_IOMMU)
+	ioctl(container, VFIO_SET_IOMMU, VFIO_TYPE1_IOMMU)
 
 	/* Get addition IOMMU info */
 	ioctl(container, VFIO_IOMMU_GET_INFO, &iommu_info);

drivers/vfio/vfio.c

@@ -76,6 +76,7 @@ struct vfio_group {
 	struct notifier_block		nb;
 	struct list_head		vfio_next;
 	struct list_head		container_next;
+	atomic_t			opened;
 };
 
 struct vfio_device {
@@ -206,6 +207,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
 	INIT_LIST_HEAD(&group->device_list);
 	mutex_init(&group->device_lock);
 	atomic_set(&group->container_users, 0);
+	atomic_set(&group->opened, 0);
 	group->iommu_group = iommu_group;
 
 	group->nb.notifier_call = vfio_iommu_group_notifier;
@@ -1236,12 +1238,22 @@ static long vfio_group_fops_compat_ioctl(struct file *filep,
 static int vfio_group_fops_open(struct inode *inode, struct file *filep)
 {
 	struct vfio_group *group;
+	int opened;
 
 	group = vfio_group_get_from_minor(iminor(inode));
 	if (!group)
 		return -ENODEV;
 
+	/* Do we need multiple instances of the group open?  Seems not. */
+	opened = atomic_cmpxchg(&group->opened, 0, 1);
+	if (opened) {
+		vfio_group_put(group);
+		return -EBUSY;
+	}
+
+	/* Is something still in use from a previous open? */
 	if (group->container) {
+		atomic_dec(&group->opened);
 		vfio_group_put(group);
 		return -EBUSY;
 	}
@@ -1259,6 +1271,8 @@ static int vfio_group_fops_release(struct inode *inode, struct file *filep)
 
 	vfio_group_try_dissolve_container(group);
 
+	atomic_dec(&group->opened);
+
 	vfio_group_put(group);
 
 	return 0;