1 files changed, 103 insertions, 45 deletions

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 842f4507883..f018d8d0f97 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -22,6 +22,7 @@
 #include <linux/idr.h>
 #include <linux/iommu.h>
 #include <linux/list.h>
+#include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/rwsem.h>
@@ -45,9 +46,7 @@ static struct vfio {
 	struct idr			group_idr;
 	struct mutex			group_lock;
 	struct cdev			group_cdev;
-	struct device			*dev;
-	dev_t				devt;
-	struct cdev			cdev;
+	dev_t				group_devt;
 	wait_queue_head_t		release_q;
 } vfio;
 
@@ -142,8 +141,7 @@ EXPORT_SYMBOL_GPL(vfio_unregister_iommu_driver);
  */
 static int vfio_alloc_group_minor(struct vfio_group *group)
 {
-	/* index 0 is used by /dev/vfio/vfio */
-	return idr_alloc(&vfio.group_idr, group, 1, MINORMASK + 1, GFP_KERNEL);
+	return idr_alloc(&vfio.group_idr, group, 0, MINORMASK + 1, GFP_KERNEL);
 }
 
 static void vfio_free_group_minor(int minor)
@@ -243,7 +241,8 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
 		}
 	}
 
-	dev = device_create(vfio.class, NULL, MKDEV(MAJOR(vfio.devt), minor),
+	dev = device_create(vfio.class, NULL,
+			    MKDEV(MAJOR(vfio.group_devt), minor),
 			    group, "%d", iommu_group_id(iommu_group));
 	if (IS_ERR(dev)) {
 		vfio_free_group_minor(minor);
@@ -268,7 +267,7 @@ static void vfio_group_release(struct kref *kref)
 
 	WARN_ON(!list_empty(&group->device_list));
 
-	device_destroy(vfio.class, MKDEV(MAJOR(vfio.devt), group->minor));
+	device_destroy(vfio.class, MKDEV(MAJOR(vfio.group_devt), group->minor));
 	list_del(&group->vfio_next);
 	vfio_free_group_minor(group->minor);
 	vfio_group_unlock_and_free(group);
@@ -350,7 +349,6 @@ struct vfio_device *vfio_group_create_device(struct vfio_group *group,
 					     void *device_data)
 {
 	struct vfio_device *device;
-	int ret;
 
 	device = kzalloc(sizeof(*device), GFP_KERNEL);
 	if (!device)
@@ -361,12 +359,7 @@ struct vfio_device *vfio_group_create_device(struct vfio_group *group,
 	device->group = group;
 	device->ops = ops;
 	device->device_data = device_data;
-
-	ret = dev_set_drvdata(dev, device);
-	if (ret) {
-		kfree(device);
-		return ERR_PTR(ret);
-	}
+	dev_set_drvdata(dev, device);
 
 	/* No need to get group_lock, caller has group reference */
 	vfio_group_get(group);
@@ -1109,7 +1102,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
 		 * We can't use anon_inode_getfd() because we need to modify
 		 * the f_mode flags directly to allow more than just ioctls
 		 */
-		ret = get_unused_fd();
+		ret = get_unused_fd_flags(O_CLOEXEC);
 		if (ret < 0) {
 			device->ops->release(device->device_data);
 			break;
@@ -1353,16 +1346,89 @@ static const struct file_operations vfio_device_fops = {
 };
 
 /**
+ * External user API, exported by symbols to be linked dynamically.
+ *
+ * The protocol includes:
+ *  1. do normal VFIO init operation:
+ *	- opening a new container;
+ *	- attaching group(s) to it;
+ *	- setting an IOMMU driver for a container.
+ * When IOMMU is set for a container, all groups in it are
+ * considered ready to use by an external user.
+ *
+ * 2. User space passes a group fd to an external user.
+ * The external user calls vfio_group_get_external_user()
+ * to verify that:
+ *	- the group is initialized;
+ *	- IOMMU is set for it.
+ * If both checks passed, vfio_group_get_external_user()
+ * increments the container user counter to prevent
+ * the VFIO group from disposal before KVM exits.
+ *
+ * 3. The external user calls vfio_external_user_iommu_id()
+ * to know an IOMMU ID.
+ *
+ * 4. When the external KVM finishes, it calls
+ * vfio_group_put_external_user() to release the VFIO group.
+ * This call decrements the container user counter.
+ */
+struct vfio_group *vfio_group_get_external_user(struct file *filep)
+{
+	struct vfio_group *group = filep->private_data;
+
+	if (filep->f_op != &vfio_group_fops)
+		return ERR_PTR(-EINVAL);
+
+	if (!atomic_inc_not_zero(&group->container_users))
+		return ERR_PTR(-EINVAL);
+
+	if (!group->container->iommu_driver ||
+			!vfio_group_viable(group)) {
+		atomic_dec(&group->container_users);
+		return ERR_PTR(-EINVAL);
+	}
+
+	vfio_group_get(group);
+
+	return group;
+}
+EXPORT_SYMBOL_GPL(vfio_group_get_external_user);
+
+void vfio_group_put_external_user(struct vfio_group *group)
+{
+	vfio_group_put(group);
+	vfio_group_try_dissolve_container(group);
+}
+EXPORT_SYMBOL_GPL(vfio_group_put_external_user);
+
+int vfio_external_user_iommu_id(struct vfio_group *group)
+{
+	return iommu_group_id(group->iommu_group);
+}
+EXPORT_SYMBOL_GPL(vfio_external_user_iommu_id);
+
+long vfio_external_check_extension(struct vfio_group *group, unsigned long arg)
+{
+	return vfio_ioctl_check_extension(group->container, arg);
+}
+EXPORT_SYMBOL_GPL(vfio_external_check_extension);
+
+/**
  * Module/class support
  */
 static char *vfio_devnode(struct device *dev, umode_t *mode)
 {
-	if (mode && (MINOR(dev->devt) == 0))
-		*mode = S_IRUGO | S_IWUGO;
-
 	return kasprintf(GFP_KERNEL, "vfio/%s", dev_name(dev));
 }
 
+static struct miscdevice vfio_dev = {
+	.minor = VFIO_MINOR,
+	.name = "vfio",
+	.fops = &vfio_fops,
+	.nodename = "vfio/vfio",
+	.mode = S_IRUGO | S_IWUGO,
+};
+
 static int __init vfio_init(void)
 {
 	int ret;
@@ -1374,6 +1440,13 @@ static int __init vfio_init(void)
 	INIT_LIST_HEAD(&vfio.iommu_drivers_list);
 	init_waitqueue_head(&vfio.release_q);
 
+	ret = misc_register(&vfio_dev);
+	if (ret) {
+		pr_err("vfio: misc device register failed\n");
+		return ret;
+	}
+
+	/* /dev/vfio/$GROUP */
 	vfio.class = class_create(THIS_MODULE, "vfio");
 	if (IS_ERR(vfio.class)) {
 		ret = PTR_ERR(vfio.class);
@@ -1382,27 +1455,14 @@ static int __init vfio_init(void)
 
 	vfio.class->devnode = vfio_devnode;
 
-	ret = alloc_chrdev_region(&vfio.devt, 0, MINORMASK, "vfio");
-	if (ret)
-		goto err_base_chrdev;
-
-	cdev_init(&vfio.cdev, &vfio_fops);
-	ret = cdev_add(&vfio.cdev, vfio.devt, 1);
+	ret = alloc_chrdev_region(&vfio.group_devt, 0, MINORMASK, "vfio");
 	if (ret)
-		goto err_base_cdev;
+		goto err_alloc_chrdev;
 
-	vfio.dev = device_create(vfio.class, NULL, vfio.devt, NULL, "vfio");
-	if (IS_ERR(vfio.dev)) {
-		ret = PTR_ERR(vfio.dev);
-		goto err_base_dev;
-	}
-
-	/* /dev/vfio/$GROUP */
 	cdev_init(&vfio.group_cdev, &vfio_group_fops);
-	ret = cdev_add(&vfio.group_cdev,
-		       MKDEV(MAJOR(vfio.devt), 1), MINORMASK - 1);
+	ret = cdev_add(&vfio.group_cdev, vfio.group_devt, MINORMASK);
 	if (ret)
-		goto err_groups_cdev;
+		goto err_cdev_add;
 
 	pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
 
@@ -1416,16 +1476,13 @@ static int __init vfio_init(void)
 
 	return 0;
 
-err_groups_cdev:
-	device_destroy(vfio.class, vfio.devt);
-err_base_dev:
-	cdev_del(&vfio.cdev);
-err_base_cdev:
-	unregister_chrdev_region(vfio.devt, MINORMASK);
-err_base_chrdev:
+err_cdev_add:
+	unregister_chrdev_region(vfio.group_devt, MINORMASK);
+err_alloc_chrdev:
 	class_destroy(vfio.class);
 	vfio.class = NULL;
 err_class:
+	misc_deregister(&vfio_dev);
 	return ret;
 }
 
@@ -1435,11 +1492,10 @@ static void __exit vfio_cleanup(void)
 
 	idr_destroy(&vfio.group_idr);
 	cdev_del(&vfio.group_cdev);
-	device_destroy(vfio.class, vfio.devt);
-	cdev_del(&vfio.cdev);
-	unregister_chrdev_region(vfio.devt, MINORMASK);
+	unregister_chrdev_region(vfio.group_devt, MINORMASK);
 	class_destroy(vfio.class);
 	vfio.class = NULL;
+	misc_deregister(&vfio_dev);
 }
 
 module_init(vfio_init);
@@ -1449,3 +1505,5 @@ MODULE_VERSION(DRIVER_VERSION);
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR(DRIVER_AUTHOR);
 MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_ALIAS_MISCDEV(VFIO_MINOR);
+MODULE_ALIAS("devname:vfio/vfio");