- Convert to misc driver to support module auto loading

- Remove unnecessary and dangerous use of device_lock
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Merge tag 'vfio-v3.14-rc1' of git://github.com/awilliam/linux-vfio

Pull vfio update from Alex Williamson:
 - convert to misc driver to support module auto loading
 - remove unnecessary and dangerous use of device_lock

* tag 'vfio-v3.14-rc1' of git://github.com/awilliam/linux-vfio:
  vfio-pci: Don't use device_lock around AER interrupt setup
  vfio: Convert control interface to misc driver
  misc: Reserve minor for VFIO

Documentation/devices.txt

@@ -409,6 +409,7 @@ Your cooperation is appreciated.
 		193 = /dev/d7s		SPARC 7-segment display
 		194 = /dev/zkshim	Zero-Knowledge network shim control
 		195 = /dev/elographics/e2201	Elographics touchscreen E271-2201
+		196 = /dev/vfio/vfio	VFIO userspace driver interface
 		198 = /dev/sexec	Signed executable interface
 		199 = /dev/scanners/cuecat :CueCat barcode scanner
 		200 = /dev/net/tun	TAP/TUN network device

drivers/vfio/pci/vfio_pci.c

@@ -872,9 +872,13 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
 		return PCI_ERS_RESULT_DISCONNECT;
 	}
 
+	mutex_lock(&vdev->igate);
+
 	if (vdev->err_trigger)
 		eventfd_signal(vdev->err_trigger, 1);
 
+	mutex_unlock(&vdev->igate);
+
 	vfio_device_put(device);
 
 	return PCI_ERS_RESULT_CAN_RECOVER;

drivers/vfio/pci/vfio_pci_intrs.c

@@ -749,54 +749,37 @@ static int vfio_pci_set_err_trigger(struct vfio_pci_device *vdev,
 				    unsigned count, uint32_t flags, void *data)
 {
 	int32_t fd = *(int32_t *)data;
-	struct pci_dev *pdev = vdev->pdev;
 
 	if ((index != VFIO_PCI_ERR_IRQ_INDEX) ||
 	    !(flags & VFIO_IRQ_SET_DATA_TYPE_MASK))
 		return -EINVAL;
 
-	/*
-	 * device_lock synchronizes setting and checking of
-	 * err_trigger. The vfio_pci_aer_err_detected() is also
-	 * called with device_lock held.
-	 */
-
 	/* DATA_NONE/DATA_BOOL enables loopback testing */
-
 	if (flags & VFIO_IRQ_SET_DATA_NONE) {
-		device_lock(&pdev->dev);
 		if (vdev->err_trigger)
 			eventfd_signal(vdev->err_trigger, 1);
-		device_unlock(&pdev->dev);
 		return 0;
 	} else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
 		uint8_t trigger = *(uint8_t *)data;
-		device_lock(&pdev->dev);
 		if (trigger && vdev->err_trigger)
 			eventfd_signal(vdev->err_trigger, 1);
-		device_unlock(&pdev->dev);
 		return 0;
 	}
 
 	/* Handle SET_DATA_EVENTFD */
-
 	if (fd == -1) {
-		device_lock(&pdev->dev);
 		if (vdev->err_trigger)
 			eventfd_ctx_put(vdev->err_trigger);
 		vdev->err_trigger = NULL;
-		device_unlock(&pdev->dev);
 		return 0;
 	} else if (fd >= 0) {
 		struct eventfd_ctx *efdctx;
 		efdctx = eventfd_ctx_fdget(fd);
 		if (IS_ERR(efdctx))
 			return PTR_ERR(efdctx);
-		device_lock(&pdev->dev);
 		if (vdev->err_trigger)
 			eventfd_ctx_put(vdev->err_trigger);
 		vdev->err_trigger = efdctx;
-		device_unlock(&pdev->dev);
 		return 0;
 	} else
 		return -EINVAL;

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				group_devt;
-	dev_t				devt;
-	struct cdev			cdev;
 	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, 0, MINORMASK + 1, GFP_KERNEL);
-	return idr_alloc(&vfio.group_idr, group, 1, 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);
@@ -1419,12 +1418,17 @@ EXPORT_SYMBOL_GPL(vfio_external_user_iommu_id);
  */
 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 @@ 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);
@@ -1444,27 +1455,14 @@ static int __init vfio_init(void)
 
 	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,
+	ret = cdev_add(&vfio.group_cdev, vfio.group_devt, MINORMASK);
-		       MKDEV(MAJOR(vfio.devt), 1), MINORMASK - 1);
 	if (ret)
-		goto err_groups_cdev;
+		goto err_cdev_add;
 
 	pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
 
@@ -1478,16 +1476,13 @@ static int __init vfio_init(void)
 
 	return 0;
 
-err_groups_cdev:
+err_cdev_add:
-	device_destroy(vfio.class, vfio.devt);
+	unregister_chrdev_region(vfio.group_devt, MINORMASK);
-err_base_dev:
+err_alloc_chrdev:
-	cdev_del(&vfio.cdev);
-err_base_cdev:
-	unregister_chrdev_region(vfio.devt, MINORMASK);
-err_base_chrdev:
 	class_destroy(vfio.class);
 	vfio.class = NULL;
 err_class:
+	misc_deregister(&vfio_dev);
 	return ret;
 }
 
@@ -1497,11 +1492,10 @@ static void __exit vfio_cleanup(void)
 
 	idr_destroy(&vfio.group_idr);
 	cdev_del(&vfio.group_cdev);
-	device_destroy(vfio.class, vfio.devt);
+	unregister_chrdev_region(vfio.group_devt, MINORMASK);
-	cdev_del(&vfio.cdev);
-	unregister_chrdev_region(vfio.devt, MINORMASK);
 	class_destroy(vfio.class);
 	vfio.class = NULL;
+	misc_deregister(&vfio_dev);
 }
 
 module_init(vfio_init);
@@ -1511,3 +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");

include/linux/miscdevice.h

@@ -30,6 +30,7 @@
 #define STORE_QUEUE_MINOR	155
 #define I2O_MINOR		166
 #define MICROCODE_MINOR		184
+#define VFIO_MINOR		196
 #define TUN_MINOR		200
 #define CUSE_MINOR		203
 #define MWAVE_MINOR		219	/* ACP/Mwave Modem */