Re: [PATCH v4 15/15] vfio: Add struct device to vfio_device

Alex Williamson
2022-09-29T16:55:31Z

Hi Kevin,

This introduced the regression discovered here:

https://lore.kernel.org/all/20220928125650.0a2ea297.alex.williamson@redhat.com/

Seems we're not releasing the resources when removing an mdev. This is
a regression, so it needs to be fixed or reverted before the merge
window. Thanks,

Alex

On Wed, 21 Sep 2022 18:44:01 +0800
Kevin Tian <kevin.tian@intel.com> wrote:

> From: Yi Liu <yi.l.liu@intel.com>
>
> 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>
> ---
> .../ABI/testing/sysfs-devices-vfio-dev | 8 +++
> MAINTAINERS | 1 +
> drivers/vfio/vfio_main.c | 64 +++++++++++++++----
> include/linux/vfio.h | 6 +-
> 4 files changed, 65 insertions(+), 14 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-devices-vfio-dev
>
> diff --git a/Documentation/ABI/testing/sysfs-devices-vfio-dev b/Documentation/ABI/testing/sysfs-devices-vfio-dev
> new file mode 100644
> index 000000000000..e21424fd9666
> --- /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 d30f26e07cd3..02c8f11b1c17 100644
> --- 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 c27449613a1d..f9d10dbcf3e6 100644
> --- 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 3cf857b1eec7..ee399a768070 100644
> --- 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);