vfio: Convert control interface to misc driver
This change allows us to support module auto loading using devname
support in userspace tools. With this, /dev/vfio/vfio will always
be present and opening it will cause the vfio module to load. This
should avoid needing to configure the system to statically load
vfio in order to get libvirt to correctly detect support for it.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 1eab4ac..21271d8 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 @@
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 @@
*/
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 @@
}
}
- 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 @@
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);
@@ -1419,12 +1418,17 @@
*/
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;
@@ -1436,6 +1440,13 @@
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/$GROUP */
vfio.class = class_create(THIS_MODULE, "vfio");
if (IS_ERR(vfio.class)) {
ret = PTR_ERR(vfio.class);
@@ -1444,27 +1455,14 @@
vfio.class->devnode = vfio_devnode;
- ret = alloc_chrdev_region(&vfio.devt, 0, MINORMASK, "vfio");
+ ret = alloc_chrdev_region(&vfio.group_devt, 0, MINORMASK, "vfio");
if (ret)
- goto err_base_chrdev;
+ goto err_alloc_chrdev;
- cdev_init(&vfio.cdev, &vfio_fops);
- ret = cdev_add(&vfio.cdev, vfio.devt, 1);
- if (ret)
- goto err_base_cdev;
-
- vfio.dev = device_create(vfio.class, NULL, vfio.devt, NULL, "vfio");
- if (IS_ERR(vfio.dev)) {
- ret = PTR_ERR(vfio.dev);
- goto err_base_dev;
- }
-
- /* /dev/vfio/$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");
@@ -1478,16 +1476,13 @@
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;
}
@@ -1497,11 +1492,10 @@
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);
@@ -1511,3 +1505,5 @@
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_ALIAS_MISCDEV(VFIO_MINOR);
+MODULE_ALIAS("devname:vfio/vfio");