vfio: Add struct device to vfio_device

and replace kref. With it a 'vfio-dev/vfioX' node is created under the
sysfs path of the parent, indicating the device is bound to a vfio
driver, e.g.:

/sys/devices/pci0000\:6f/0000\:6f\:01.0/vfio-dev/vfio0

It is also a preparatory step toward adding cdev for supporting future
device-oriented uAPI.

Add Documentation/ABI/testing/sysfs-devices-vfio-dev.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20220921104401.38898-16-kevin.tian@intel.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/Documentation/ABI/testing/sysfs-devices-vfio-dev b/Documentation/ABI/testing/sysfs-devices-vfio-dev
new file mode 100644 (file)
index 0000000..e21424f
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-vfio-dev
@@ -0,0 +1,8 @@
+What:           /sys/.../<device>/vfio-dev/vfioX/
+Date:           September 2022
+Contact:        Yi Liu <yi.l.liu@intel.com>
+Description:
+                This directory is created when the device is bound to a
+                vfio driver. The layout under this directory matches what
+                exists for a standard 'struct device'. 'X' is a unique
+                index marking this device in vfio.

diff --git a/MAINTAINERS b/MAINTAINERS
index d30f26e..02c8f11 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21312,6 +21312,7 @@ R:      Cornelia Huck <cohuck@redhat.com>
 L:     kvm@vger.kernel.org
 S:     Maintained
 T:     git git://github.com/awilliam/linux-vfio.git
+F:     Documentation/ABI/testing/sysfs-devices-vfio-dev
 F:     Documentation/driver-api/vfio.rst
 F:     drivers/vfio/
 F:     include/linux/vfio.h

diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index c274496..f9d10db 100644 (file)
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -49,6 +49,8 @@ static struct vfio {
        struct mutex                    group_lock; /* locks group_list */
        struct ida                      group_ida;
        dev_t                           group_devt;
+       struct class                    *device_class;
+       struct ida                      device_ida;
 } vfio;
 
 struct vfio_iommu_driver {
@@ -485,12 +487,13 @@ static struct vfio_device *vfio_group_get_device(struct vfio_group *group,
  * VFIO driver API
  */
 /* Release helper called by vfio_put_device() */
-void vfio_device_release(struct kref *kref)
+static void vfio_device_release(struct device *dev)
 {
        struct vfio_device *device =
-                       container_of(kref, struct vfio_device, kref);
+                       container_of(dev, struct vfio_device, device);
 
        vfio_release_device_set(device);
+       ida_free(&vfio.device_ida, device->index);
 
        /*
         * kvfree() cannot be done here due to a life cycle mess in
@@ -500,7 +503,6 @@ void vfio_device_release(struct kref *kref)
         */
        device->ops->release(device);
 }
-EXPORT_SYMBOL_GPL(vfio_device_release);
 
 /*
  * Allocate and initialize vfio_device so it can be registered to vfio
@@ -548,6 +550,13 @@ int vfio_init_device(struct vfio_device *device, struct device *dev,
 {
        int ret;
 
+       ret = ida_alloc_max(&vfio.device_ida, MINORMASK, GFP_KERNEL);
+       if (ret < 0) {
+               dev_dbg(dev, "Error to alloc index\n");
+               return ret;
+       }
+
+       device->index = ret;
        init_completion(&device->comp);
        device->dev = dev;
        device->ops = ops;
@@ -558,11 +567,15 @@ int vfio_init_device(struct vfio_device *device, struct device *dev,
                        goto out_uninit;
        }
 
-       kref_init(&device->kref);
+       device_initialize(&device->device);
+       device->device.release = vfio_device_release;
+       device->device.class = vfio.device_class;
+       device->device.parent = device->dev;
        return 0;
 
 out_uninit:
        vfio_release_device_set(device);
+       ida_free(&vfio.device_ida, device->index);
        return ret;
 }
 EXPORT_SYMBOL_GPL(vfio_init_device);
@@ -659,6 +672,7 @@ static int __vfio_register_dev(struct vfio_device *device,
                struct vfio_group *group)
 {
        struct vfio_device *existing_device;
+       int ret;
 
        if (IS_ERR(group))
                return PTR_ERR(group);
@@ -675,16 +689,21 @@ static int __vfio_register_dev(struct vfio_device *device,
                dev_WARN(device->dev, "Device already exists on group %d\n",
                         iommu_group_id(group->iommu_group));
                vfio_device_put_registration(existing_device);
-               if (group->type == VFIO_NO_IOMMU ||
-                   group->type == VFIO_EMULATED_IOMMU)
-                       iommu_group_remove_device(device->dev);
-               vfio_group_put(group);
-               return -EBUSY;
+               ret = -EBUSY;
+               goto err_out;
        }
 
        /* Our reference on group is moved to the device */
        device->group = group;
 
+       ret = dev_set_name(&device->device, "vfio%d", device->index);
+       if (ret)
+               goto err_out;
+
+       ret = device_add(&device->device);
+       if (ret)
+               goto err_out;
+
        /* Refcounting can't start until the driver calls register */
        refcount_set(&device->refcount, 1);
 
@@ -693,6 +712,12 @@ static int __vfio_register_dev(struct vfio_device *device,
        mutex_unlock(&group->device_lock);
 
        return 0;
+err_out:
+       if (group->type == VFIO_NO_IOMMU ||
+           group->type == VFIO_EMULATED_IOMMU)
+               iommu_group_remove_device(device->dev);
+       vfio_group_put(group);
+       return ret;
 }
 
 int vfio_register_group_dev(struct vfio_device *device)
@@ -779,6 +804,9 @@ void vfio_unregister_group_dev(struct vfio_device *device)
        list_del(&device->group_next);
        mutex_unlock(&group->device_lock);
 
+       /* Balances device_add in register path */
+       device_del(&device->device);
+
        if (group->type == VFIO_NO_IOMMU || group->type == VFIO_EMULATED_IOMMU)
                iommu_group_remove_device(device->dev);
 
@@ -2362,6 +2390,7 @@ static int __init vfio_init(void)
        int ret;
 
        ida_init(&vfio.group_ida);
+       ida_init(&vfio.device_ida);
        mutex_init(&vfio.group_lock);
        mutex_init(&vfio.iommu_drivers_lock);
        INIT_LIST_HEAD(&vfio.group_list);
@@ -2377,11 +2406,18 @@ static int __init vfio_init(void)
        vfio.class = class_create(THIS_MODULE, "vfio");
        if (IS_ERR(vfio.class)) {
                ret = PTR_ERR(vfio.class);
-               goto err_class;
+               goto err_group_class;
        }
 
        vfio.class->devnode = vfio_devnode;
 
+       /* /sys/class/vfio-dev/vfioX */
+       vfio.device_class = class_create(THIS_MODULE, "vfio-dev");
+       if (IS_ERR(vfio.device_class)) {
+               ret = PTR_ERR(vfio.device_class);
+               goto err_dev_class;
+       }
+
        ret = alloc_chrdev_region(&vfio.group_devt, 0, MINORMASK + 1, "vfio");
        if (ret)
                goto err_alloc_chrdev;
@@ -2398,9 +2434,12 @@ static int __init vfio_init(void)
 err_driver_register:
        unregister_chrdev_region(vfio.group_devt, MINORMASK + 1);
 err_alloc_chrdev:
+       class_destroy(vfio.device_class);
+       vfio.device_class = NULL;
+err_dev_class:
        class_destroy(vfio.class);
        vfio.class = NULL;
-err_class:
+err_group_class:
        misc_deregister(&vfio_dev);
        return ret;
 }
@@ -2412,8 +2451,11 @@ static void __exit vfio_cleanup(void)
 #ifdef CONFIG_VFIO_NOIOMMU
        vfio_unregister_iommu_driver(&vfio_noiommu_ops);
 #endif
+       ida_destroy(&vfio.device_ida);
        ida_destroy(&vfio.group_ida);
        unregister_chrdev_region(vfio.group_devt, MINORMASK + 1);
+       class_destroy(vfio.device_class);
+       vfio.device_class = NULL;
        class_destroy(vfio.class);
        vfio.class = NULL;
        misc_deregister(&vfio_dev);

diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 3cf857b..ee399a7 100644 (file)
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -47,7 +47,8 @@ struct vfio_device {
        struct kvm *kvm;
 
        /* Members below here are private, not for driver use */
-       struct kref kref;       /* object life cycle */
+       unsigned int index;
+       struct device device;   /* device.kref covers object life circle */
        refcount_t refcount;    /* user count on registered device*/
        unsigned int open_count;
        struct completion comp;
@@ -178,10 +179,9 @@ struct vfio_device *_vfio_alloc_device(size_t size, struct device *dev,
 int vfio_init_device(struct vfio_device *device, struct device *dev,
                     const struct vfio_device_ops *ops);
 void vfio_free_device(struct vfio_device *device);
-void vfio_device_release(struct kref *kref);
 static inline void vfio_put_device(struct vfio_device *device)
 {
-       kref_put(&device->kref, vfio_device_release);
+       put_device(&device->device);
 }
 
 int vfio_register_group_dev(struct vfio_device *device);