RE: [PATCH V4 3/6] mdev: introduce device specific ops

Parav Pandit
2019-10-20T23:41:53Z

> -----Original Message-----
> From: Jason Wang <jasowang@redhat.com>
> Sent: Thursday, October 17, 2019 5:49 AM
> To: kvm@vger.kernel.org; linux-s390@vger.kernel.org; linux-
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> lingshan.zhu@intel.com; Ido Shamay <idos@mellanox.com>;
> eperezma@redhat.com; lulu@redhat.com; Parav Pandit
> <parav@mellanox.com>; christophe.de.dinechin@gmail.com;
> kevin.tian@intel.com; stefanha@redhat.com; Jason Wang
> <jasowang@redhat.com>
> Subject: [PATCH V4 3/6] mdev: introduce device specific ops
>
> Currently, except for the create and remove, the rest of mdev_parent_ops is
> designed for vfio-mdev driver only and may not help for kernel mdev driver.
> With the help of class id, this patch introduces device specific callbacks
> inside mdev_device structure. This allows different set of callback to be used
> by vfio-mdev and virtio-mdev.
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> .../driver-api/vfio-mediated-device.rst | 25 +++++----
> MAINTAINERS | 1 +
> drivers/gpu/drm/i915/gvt/kvmgt.c | 18 ++++---
> drivers/s390/cio/vfio_ccw_ops.c | 18 ++++---
> drivers/s390/crypto/vfio_ap_ops.c | 14 +++--
> drivers/vfio/mdev/mdev_core.c | 18 +++++--
> drivers/vfio/mdev/mdev_private.h | 1 +
> drivers/vfio/mdev/vfio_mdev.c | 37 ++++++-------
> include/linux/mdev.h | 45 ++++------------
> include/linux/vfio_mdev.h | 52 +++++++++++++++++++
> samples/vfio-mdev/mbochs.c | 20 ++++---
> samples/vfio-mdev/mdpy.c | 20 ++++---
> samples/vfio-mdev/mtty.c | 18 ++++---
> 13 files changed, 184 insertions(+), 103 deletions(-) create mode 100644
> include/linux/vfio_mdev.h
>
> diff --git a/Documentation/driver-api/vfio-mediated-device.rst
> b/Documentation/driver-api/vfio-mediated-device.rst
> index f9a78d75a67a..0cca84d19603 100644
> --- a/Documentation/driver-api/vfio-mediated-device.rst
> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> @@ -152,11 +152,22 @@ callbacks per mdev parent device, per mdev type,
> or any other categorization.
> Vendor drivers are expected to be fully asynchronous in this respect or
> provide their own internal resource protection.)
>
> -The callbacks in the mdev_parent_ops structure are as follows:
> -
> -* open: open callback of mediated device
> -* close: close callback of mediated device
> -* ioctl: ioctl callback of mediated device
> +As multiple types of mediated devices may be supported, the device must
> +set up the class id and the device specific callbacks in create()
> +callback. E.g for vfio-mdev device it needs to be done through:
> +
> + int mdev_set_vfio_ops(struct mdev_device *mdev,
> + const struct vfio_mdev_ops *vfio_ops);
> +
> +The class id (set to MDEV_CLASS_ID_VFIO) is used to match a device with
> +an mdev driver via its id table. The device specific callbacks
> +(specified in *ops) are obtainable via mdev_get_dev_ops() (for use by
> +the mdev bus driver). A vfio-mdev device (class id MDEV_CLASS_ID_VFIO)
> +uses the following device-specific ops:
> +
> +* open: open callback of vfio mediated device
> +* close: close callback of vfio mediated device
> +* ioctl: ioctl callback of vfio mediated device
> * read : read emulation callback
> * write: write emulation callback
> * mmap: mmap emulation callback
> @@ -167,10 +178,6 @@ register itself with the mdev core driver::
> extern int mdev_register_device(struct device *dev,
> const struct mdev_parent_ops *ops);
>
> -It is also required to specify the class_id in create() callback through::
> -
> - int mdev_set_class(struct mdev_device *mdev, u16 id);
> -
> However, the mdev_parent_ops structure is not required in the function call
> that a driver should use to unregister itself with the mdev core driver::
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 8824f61cd2c0..3d196a023b5e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -17127,6 +17127,7 @@ S: Maintained
> F: Documentation/driver-api/vfio-mediated-device.rst
> F: drivers/vfio/mdev/
> F: include/linux/mdev.h
> +F: include/linux/vfio_mdev.h
> F: samples/vfio-mdev/
>
> VFIO PLATFORM DRIVER
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c
> b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 6420f0dbd31b..306f934c7857 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -42,6 +42,7 @@
> #include <linux/kvm_host.h>
> #include <linux/vfio.h>
> #include <linux/mdev.h>
> +#include <linux/vfio_mdev.h>
> #include <linux/debugfs.h>
>
> #include <linux/nospec.h>
> @@ -643,6 +644,8 @@ static void kvmgt_put_vfio_device(void *vgpu)
> vfio_device_put(((struct intel_vgpu *)vgpu)->vdev.vfio_device); }
>
> +static const struct vfio_mdev_device_ops intel_vfio_vgpu_dev_ops;
> +
> static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
> {
> struct intel_vgpu *vgpu = NULL;
> @@ -678,7 +681,7 @@ static int intel_vgpu_create(struct kobject *kobj,
> struct mdev_device *mdev)
> dev_name(mdev_dev(mdev)));
> ret = 0;
>
> - mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> + mdev_set_vfio_ops(mdev, &intel_vfio_vgpu_dev_ops);
> out:
> return ret;
> }
> @@ -1599,20 +1602,21 @@ static const struct attribute_group
> *intel_vgpu_groups[] = {
> NULL,
> };
>
> -static struct mdev_parent_ops intel_vgpu_ops = {
> - .mdev_attr_groups = intel_vgpu_groups,
> - .create = intel_vgpu_create,
> - .remove = intel_vgpu_remove,
> -
> +static const struct vfio_mdev_device_ops intel_vfio_vgpu_dev_ops = {
> .open = intel_vgpu_open,
> .release = intel_vgpu_release,
> -
> .read = intel_vgpu_read,
> .write = intel_vgpu_write,
> .mmap = intel_vgpu_mmap,
> .ioctl = intel_vgpu_ioctl,
> };
>
> +static struct mdev_parent_ops intel_vgpu_ops = {
> + .mdev_attr_groups = intel_vgpu_groups,
> + .create = intel_vgpu_create,
> + .remove = intel_vgpu_remove,
> +};
> +
> static int kvmgt_host_init(struct device *dev, void *gvt, const void *ops) {
> struct attribute **kvm_type_attrs;
> diff --git a/drivers/s390/cio/vfio_ccw_ops.c
> b/drivers/s390/cio/vfio_ccw_ops.c index cf2c013ae32f..6e606cdb1aa9 100644
> --- a/drivers/s390/cio/vfio_ccw_ops.c
> +++ b/drivers/s390/cio/vfio_ccw_ops.c
> @@ -12,6 +12,7 @@
>
> #include <linux/vfio.h>
> #include <linux/mdev.h>
> +#include <linux/vfio_mdev.h>
> #include <linux/nospec.h>
> #include <linux/slab.h>
>
> @@ -110,6 +111,8 @@ static struct attribute_group *mdev_type_groups[] =
> {
> NULL,
> };
>
> +static const struct vfio_mdev_device_ops vfio_mdev_ops;
> +
> static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device
> *mdev) {
> struct vfio_ccw_private *private =
> @@ -129,7 +132,7 @@ static int vfio_ccw_mdev_create(struct kobject *kobj,
> struct mdev_device *mdev)
> private->sch->schid.ssid,
> private->sch->schid.sch_no);
>
> - mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> + mdev_set_vfio_ops(mdev, &vfio_mdev_ops);
> return 0;
> }
>
> @@ -575,11 +578,7 @@ static ssize_t vfio_ccw_mdev_ioctl(struct
> mdev_device *mdev,
> }
> }
>
> -static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
> - .owner = THIS_MODULE,
> - .supported_type_groups = mdev_type_groups,
> - .create = vfio_ccw_mdev_create,
> - .remove = vfio_ccw_mdev_remove,
> +static const struct vfio_mdev_device_ops vfio_mdev_ops = {
> .open = vfio_ccw_mdev_open,
> .release = vfio_ccw_mdev_release,
> .read = vfio_ccw_mdev_read,
> @@ -587,6 +586,13 @@ static const struct mdev_parent_ops
> vfio_ccw_mdev_ops = {
> .ioctl = vfio_ccw_mdev_ioctl,
> };
>
> +static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
> + .owner = THIS_MODULE,
> + .supported_type_groups = mdev_type_groups,
> + .create = vfio_ccw_mdev_create,
> + .remove = vfio_ccw_mdev_remove,
> +};
> +
> int vfio_ccw_mdev_reg(struct subchannel *sch) {
> return mdev_register_device(&sch->dev, &vfio_ccw_mdev_ops); diff -
> -git a/drivers/s390/crypto/vfio_ap_ops.c
> b/drivers/s390/crypto/vfio_ap_ops.c
> index 07c31070afeb..195c8f4c6f10 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -16,6 +16,7 @@
> #include <linux/bitops.h>
> #include <linux/kvm_host.h>
> #include <linux/module.h>
> +#include <linux/vfio_mdev.h>
> #include <asm/kvm.h>
> #include <asm/zcrypt.h>
>
> @@ -321,6 +322,8 @@ static void vfio_ap_matrix_init(struct ap_config_info
> *info,
> matrix->adm_max = info->apxa ? info->Nd : 15; }
>
> +static const struct vfio_mdev_device_ops vfio_mdev_ops;
> +
> static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device
> *mdev) {
> struct ap_matrix_mdev *matrix_mdev;
> @@ -343,7 +346,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj,
> struct mdev_device *mdev)
> list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
> mutex_unlock(&matrix_dev->lock);
>
> - mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> + mdev_set_vfio_ops(mdev, &vfio_mdev_ops);
> return 0;
> }
>
> @@ -1281,15 +1284,18 @@ static ssize_t vfio_ap_mdev_ioctl(struct
> mdev_device *mdev,
> return ret;
> }
>
> +static const struct vfio_mdev_device_ops vfio_mdev_ops = {
> + .open = vfio_ap_mdev_open,
> + .release = vfio_ap_mdev_release,
> + .ioctl = vfio_ap_mdev_ioctl,
> +};
> +
> static const struct mdev_parent_ops vfio_ap_matrix_ops = {
> .owner = THIS_MODULE,
> .supported_type_groups = vfio_ap_mdev_type_groups,
> .mdev_attr_groups = vfio_ap_mdev_attr_groups,
> .create = vfio_ap_mdev_create,
> .remove = vfio_ap_mdev_remove,
> - .open = vfio_ap_mdev_open,
> - .release = vfio_ap_mdev_release,
> - .ioctl = vfio_ap_mdev_ioctl,
> };
>
> int vfio_ap_mdev_register(void)
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index 3a9c52d71b4e..d0f3113c8071 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -45,15 +45,23 @@ void mdev_set_drvdata(struct mdev_device *mdev,
> void *data) } EXPORT_SYMBOL(mdev_set_drvdata);
>
> -/* Specify the class for the mdev device, this must be called during
> - * create() callback.
> +/* Specify the VFIO device ops for the mdev device, this
> + * must be called during create() callback for VFIO mdev device.
> */
> -void mdev_set_class(struct mdev_device *mdev, u16 id)
I think you should keep the mdev_set_class API and let mdev_set_vfio_ops call it. Even though its two line function.
The reason to avoid a code churn in short time with mlx5_core patch which will only call mdev_set_class(), as it doesn't have any ops yet.

> +void mdev_set_vfio_ops(struct mdev_device *mdev,
> + const struct vfio_mdev_device_ops *vfio_ops)
> {
> WARN_ON(mdev->class_id);
> - mdev->class_id = id;
> + mdev->class_id = MDEV_CLASS_ID_VFIO;
> + mdev->device_ops = vfio_ops;
> }
> -EXPORT_SYMBOL(mdev_set_class);
> +EXPORT_SYMBOL(mdev_set_vfio_ops);
> +
> +const void *mdev_get_dev_ops(struct mdev_device *mdev) {
> + return mdev->device_ops;
> +}
> +EXPORT_SYMBOL(mdev_get_dev_ops);
>
> struct device *mdev_dev(struct mdev_device *mdev) { diff --git
> a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
> index c65f436c1869..b666805f0b1f 100644
> --- a/drivers/vfio/mdev/mdev_private.h
> +++ b/drivers/vfio/mdev/mdev_private.h
> @@ -34,6 +34,7 @@ struct mdev_device {
> struct device *iommu_device;
> bool active;
> u16 class_id;
> + const void *device_ops;
Instead of void *, this should be union vfio_ops and virtio_ops.
> };
>
> #define to_mdev_device(dev) container_of(dev, struct mdev_device, dev)
> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
> index cb701cd646f0..6b6b92011436 100644
> --- a/drivers/vfio/mdev/vfio_mdev.c
> +++ b/drivers/vfio/mdev/vfio_mdev.c
> @@ -14,6 +14,7 @@
> #include <linux/slab.h>
> #include <linux/vfio.h>
> #include <linux/mdev.h>
> +#include <linux/vfio_mdev.h>
>
> #include "mdev_private.h"
>
> @@ -24,16 +25,16 @@
> static int vfio_mdev_open(void *device_data) {
> struct mdev_device *mdev = device_data;
> - struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_device_ops *ops =
> mdev_get_dev_ops(mdev);
> int ret;
>
> - if (unlikely(!parent->ops->open))
> + if (unlikely(!ops->open))
> return -EINVAL;
>
> if (!try_module_get(THIS_MODULE))
> return -ENODEV;
>
> - ret = parent->ops->open(mdev);
> + ret = ops->open(mdev);
> if (ret)
> module_put(THIS_MODULE);
>
> @@ -43,10 +44,10 @@ static int vfio_mdev_open(void *device_data) static
> void vfio_mdev_release(void *device_data) {
> struct mdev_device *mdev = device_data;
> - struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_device_ops *ops =
> mdev_get_dev_ops(mdev);
>
> - if (likely(parent->ops->release))
> - parent->ops->release(mdev);
> + if (likely(ops->release))
> + ops->release(mdev);
>
> module_put(THIS_MODULE);
> }
> @@ -55,47 +56,47 @@ static long vfio_mdev_unlocked_ioctl(void
> *device_data,
> unsigned int cmd, unsigned long arg) {
> struct mdev_device *mdev = device_data;
> - struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_device_ops *ops =
> mdev_get_dev_ops(mdev);
>
> - if (unlikely(!parent->ops->ioctl))
> + if (unlikely(!ops->ioctl))
> return -EINVAL;
>
> - return parent->ops->ioctl(mdev, cmd, arg);
> + return ops->ioctl(mdev, cmd, arg);
> }
>
> static ssize_t vfio_mdev_read(void *device_data, char __user *buf,
> size_t count, loff_t *ppos)
> {
> struct mdev_device *mdev = device_data;
> - struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_device_ops *ops =
> mdev_get_dev_ops(mdev);
>
> - if (unlikely(!parent->ops->read))
> + if (unlikely(!ops->read))
> return -EINVAL;
>
> - return parent->ops->read(mdev, buf, count, ppos);
> + return ops->read(mdev, buf, count, ppos);
> }
>
> static ssize_t vfio_mdev_write(void *device_data, const char __user *buf,
> size_t count, loff_t *ppos)
> {
> struct mdev_device *mdev = device_data;
> - struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_device_ops *ops =
> mdev_get_dev_ops(mdev);
>
> - if (unlikely(!parent->ops->write))
> + if (unlikely(!ops->write))
> return -EINVAL;
>
> - return parent->ops->write(mdev, buf, count, ppos);
> + return ops->write(mdev, buf, count, ppos);
> }
>
> static int vfio_mdev_mmap(void *device_data, struct vm_area_struct *vma)
> {
> struct mdev_device *mdev = device_data;
> - struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_device_ops *ops =
> mdev_get_dev_ops(mdev);
>
> - if (unlikely(!parent->ops->mmap))
> + if (unlikely(!ops->mmap))
> return -EINVAL;
>
> - return parent->ops->mmap(mdev, vma);
> + return ops->mmap(mdev, vma);
> }
>
> static const struct vfio_device_ops vfio_mdev_dev_ops = { diff --git
> a/include/linux/mdev.h b/include/linux/mdev.h index
> 78b69d09eb54..3d29e09e20c9 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -10,7 +10,13 @@
> #ifndef MDEV_H
> #define MDEV_H
>
> +#include <linux/types.h>
> +#include <linux/device.h>
> +#include <linux/mdev.h>
> +#include <uapi/linux/uuid.h>
> +
> struct mdev_device;
> +struct vfio_mdev_device_ops;
>
> /*
> * Called by the parent device driver to set the device which represents @@
> -48,30 +54,7 @@ struct device *mdev_get_iommu_device(struct device
> *dev);
> * @mdev: mdev_device device structure which is being
> * destroyed
> * Returns integer: success (0) or error (< 0)
> - * @open: Open mediated device.
> - * @mdev: mediated device.
> - * Returns integer: success (0) or error (< 0)
> - * @release: release mediated device
> - * @mdev: mediated device.
> - * @read: Read emulation callback
> - * @mdev: mediated device structure
> - * @buf: read buffer
> - * @count: number of bytes to read
> - * @ppos: address.
> - * Retuns number on bytes read on success or error.
> - * @write: Write emulation callback
> - * @mdev: mediated device structure
> - * @buf: write buffer
> - * @count: number of bytes to be written
> - * @ppos: address.
> - * Retuns number on bytes written on success or error.
> - * @ioctl: IOCTL callback
> - * @mdev: mediated device structure
> - * @cmd: ioctl command
> - * @arg: arguments to ioctl
> - * @mmap: mmap callback
> - * @mdev: mediated device structure
> - * @vma: vma structure
> + *
> * Parent device that support mediated device should be registered with
> mdev
> * module with mdev_parent_ops structure.
> **/
> @@ -83,15 +66,6 @@ struct mdev_parent_ops {
>
> int (*create)(struct kobject *kobj, struct mdev_device *mdev);
> int (*remove)(struct mdev_device *mdev);
> - int (*open)(struct mdev_device *mdev);
> - void (*release)(struct mdev_device *mdev);
> - ssize_t (*read)(struct mdev_device *mdev, char __user *buf,
> - size_t count, loff_t *ppos);
> - ssize_t (*write)(struct mdev_device *mdev, const char __user *buf,
> - size_t count, loff_t *ppos);
> - long (*ioctl)(struct mdev_device *mdev, unsigned int cmd,
> - unsigned long arg);
> - int (*mmap)(struct mdev_device *mdev, struct vm_area_struct
> *vma);
> };
>
> /* interface for exporting mdev supported type attributes */ @@ -133,8
> +107,11 @@ struct mdev_driver {
>
> void *mdev_get_drvdata(struct mdev_device *mdev); void
> mdev_set_drvdata(struct mdev_device *mdev, void *data);
> +
Unrelated line change for this patch. Please remove.

> const guid_t *mdev_uuid(struct mdev_device *mdev); -void
> mdev_set_class(struct mdev_device *mdev, u16 id);
> +void mdev_set_vfio_ops(struct mdev_device *mdev,
> + const struct vfio_mdev_device_ops *vfio_ops); const
> void
> +*mdev_get_dev_ops(struct mdev_device *mdev);
>
Since you have the set_vfio_ops, its better to have get_vfio_ops() and similarly get_virtio_ops.

> extern struct bus_type mdev_bus_type;
>
> diff --git a/include/linux/vfio_mdev.h b/include/linux/vfio_mdev.h new file
> mode 100644 index 000000000000..3907c5371c2b
> --- /dev/null
> +++ b/include/linux/vfio_mdev.h
This file name is confusing.
vfio_mdev_ops.h is more accurate name of what it intends to achieve.
If you see this file expanding scope beyond ops, this file name looks fine.

> @@ -0,0 +1,52 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * VFIO Mediated device definition
> + */
> +
> +#ifndef VFIO_MDEV_H
> +#define VFIO_MDEV_H
> +
> +#include <linux/mdev.h>
> +
> +/**
> + * struct vfio_mdev_device_ops - Structure to be registered for each
> + * mdev device to register the device to vfio-mdev module.
> + *
> + * @open: Open mediated device.
> + * @mdev: mediated device.
> + * Returns integer: success (0) or error (< 0)
> + * @release: release mediated device
> + * @mdev: mediated device.
> + * @read: Read emulation callback
> + * @mdev: mediated device structure
> + * @buf: read buffer
> + * @count: number of bytes to read
> + * @ppos: address.
> + * Retuns number on bytes read on success or error.
> + * @write: Write emulation callback
> + * @mdev: mediated device structure
> + * @buf: write buffer
> + * @count: number of bytes to be written
> + * @ppos: address.
> + * Retuns number on bytes written on success or error.
> + * @ioctl: IOCTL callback
> + * @mdev: mediated device structure
> + * @cmd: ioctl command
> + * @arg: arguments to ioctl
> + * @mmap: mmap callback
> + * @mdev: mediated device structure
> + * @vma: vma structure
> + */
> +struct vfio_mdev_device_ops {
> + int (*open)(struct mdev_device *mdev);
> + void (*release)(struct mdev_device *mdev);
> + ssize_t (*read)(struct mdev_device *mdev, char __user *buf,
> + size_t count, loff_t *ppos);
> + ssize_t (*write)(struct mdev_device *mdev, const char __user *buf,
> + size_t count, loff_t *ppos);
> + long (*ioctl)(struct mdev_device *mdev, unsigned int cmd,
> + unsigned long arg);
> + int (*mmap)(struct mdev_device *mdev, struct vm_area_struct
> *vma);
> +};
> +
> +#endif
> diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
> index 115bc5074656..37abdf1b27a8 100644
> --- a/samples/vfio-mdev/mbochs.c
> +++ b/samples/vfio-mdev/mbochs.c
> @@ -30,6 +30,7 @@
> #include <linux/iommu.h>
> #include <linux/sysfs.h>
> #include <linux/mdev.h>
> +#include <linux/vfio_mdev.h>
> #include <linux/pci.h>
> #include <linux/dma-buf.h>
> #include <linux/highmem.h>
> @@ -516,6 +517,8 @@ static int mbochs_reset(struct mdev_device *mdev)
> return 0;
> }
>
> +static const struct vfio_mdev_device_ops vfio_mdev_ops;
> +
> static int mbochs_create(struct kobject *kobj, struct mdev_device *mdev) {
> const struct mbochs_type *type = mbochs_find_type(kobj); @@ -
> 561,7 +564,7 @@ static int mbochs_create(struct kobject *kobj, struct
> mdev_device *mdev)
> mbochs_reset(mdev);
>
> mbochs_used_mbytes += type->mbytes;
> - mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> + mdev_set_vfio_ops(mdev, &vfio_mdev_ops);
> return 0;
>
> err_mem:
> @@ -1419,12 +1422,7 @@ static struct attribute_group
> *mdev_type_groups[] = {
> NULL,
> };
>
> -static const struct mdev_parent_ops mdev_fops = {
> - .owner = THIS_MODULE,
> - .mdev_attr_groups = mdev_dev_groups,
> - .supported_type_groups = mdev_type_groups,
> - .create = mbochs_create,
> - .remove = mbochs_remove,
> +static const struct vfio_mdev_device_ops vfio_mdev_ops = {
> .open = mbochs_open,
> .release = mbochs_close,
> .read = mbochs_read,
> @@ -1433,6 +1431,14 @@ static const struct mdev_parent_ops mdev_fops =
> {
> .mmap = mbochs_mmap,
> };
>
> +static const struct mdev_parent_ops mdev_fops = {
> + .owner = THIS_MODULE,
> + .mdev_attr_groups = mdev_dev_groups,
> + .supported_type_groups = mdev_type_groups,
> + .create = mbochs_create,
> + .remove = mbochs_remove,
> +};
> +
> static const struct file_operations vd_fops = {
> .owner = THIS_MODULE,
> };
> diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c index
> 665614574d50..f21c795c40e4 100644
> --- a/samples/vfio-mdev/mdpy.c
> +++ b/samples/vfio-mdev/mdpy.c
> @@ -26,6 +26,7 @@
> #include <linux/iommu.h>
> #include <linux/sysfs.h>
> #include <linux/mdev.h>
> +#include <linux/vfio_mdev.h>
> #include <linux/pci.h>
> #include <drm/drm_fourcc.h>
> #include "mdpy-defs.h"
> @@ -226,6 +227,8 @@ static int mdpy_reset(struct mdev_device *mdev)
> return 0;
> }
>
> +static const struct vfio_mdev_device_ops vfio_mdev_ops;
> +
> static int mdpy_create(struct kobject *kobj, struct mdev_device *mdev) {
> const struct mdpy_type *type = mdpy_find_type(kobj); @@ -269,7
> +272,7 @@ static int mdpy_create(struct kobject *kobj, struct mdev_device
> *mdev)
> mdpy_reset(mdev);
>
> mdpy_count++;
> - mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> + mdev_set_vfio_ops(mdev, &vfio_mdev_ops);
> return 0;
> }
>
> @@ -726,12 +729,7 @@ static struct attribute_group *mdev_type_groups[]
> = {
> NULL,
> };
>
> -static const struct mdev_parent_ops mdev_fops = {
> - .owner = THIS_MODULE,
> - .mdev_attr_groups = mdev_dev_groups,
> - .supported_type_groups = mdev_type_groups,
> - .create = mdpy_create,
> - .remove = mdpy_remove,
> +static const struct vfio_mdev_device_ops vfio_mdev_ops = {
> .open = mdpy_open,
> .release = mdpy_close,
> .read = mdpy_read,
> @@ -740,6 +738,14 @@ static const struct mdev_parent_ops mdev_fops = {
> .mmap = mdpy_mmap,
> };
>
> +static const struct mdev_parent_ops mdev_fops = {
> + .owner = THIS_MODULE,
> + .mdev_attr_groups = mdev_dev_groups,
> + .supported_type_groups = mdev_type_groups,
> + .create = mdpy_create,
> + .remove = mdpy_remove,
> +};
> +
> static const struct file_operations vd_fops = {
> .owner = THIS_MODULE,
> };
> diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c index
> 90da12ff7fd9..b829f33b98f5 100644
> --- a/samples/vfio-mdev/mtty.c
> +++ b/samples/vfio-mdev/mtty.c
> @@ -27,6 +27,7 @@
> #include <linux/ctype.h>
> #include <linux/file.h>
> #include <linux/mdev.h>
> +#include <linux/vfio_mdev.h>
> #include <linux/pci.h>
> #include <linux/serial.h>
> #include <uapi/linux/serial_reg.h>
> @@ -708,6 +709,8 @@ static ssize_t mdev_access(struct mdev_device
> *mdev, u8 *buf, size_t count,
> return ret;
> }
>
> +static const struct vfio_mdev_device_ops vfio_dev_ops;
> +
> static int mtty_create(struct kobject *kobj, struct mdev_device *mdev) {
> struct mdev_state *mdev_state;
> @@ -755,7 +758,7 @@ static int mtty_create(struct kobject *kobj, struct
> mdev_device *mdev)
> list_add(&mdev_state->next, &mdev_devices_list);
> mutex_unlock(&mdev_list_lock);
>
> - mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> + mdev_set_vfio_ops(mdev, &vfio_dev_ops);
> return 0;
> }
>
> @@ -1388,6 +1391,14 @@ static struct attribute_group
> *mdev_type_groups[] = {
> NULL,
> };
>
> +static const struct vfio_mdev_device_ops vfio_dev_ops = {
> + .open = mtty_open,
> + .release = mtty_close,
> + .read = mtty_read,
> + .write = mtty_write,
> + .ioctl = mtty_ioctl,
> +};
> +
Since hunk shows that vfio_dev_ops added new here, it is better to drop the extra white space mixed with tab alignment.
Just have single white space like below.

.open = mtty_open,
.release = mtty_close,
.read = mtty_read,
.write = mtty_write,
.ioctl = mtty_ioctl

> static const struct mdev_parent_ops mdev_fops = {
> .owner = THIS_MODULE,
> .dev_attr_groups = mtty_dev_groups,
> @@ -1395,11 +1406,6 @@ static const struct mdev_parent_ops mdev_fops =
> {
> .supported_type_groups = mdev_type_groups,
> .create = mtty_create,
> .remove = mtty_remove,
> - .open = mtty_open,
> - .release = mtty_close,
> - .read = mtty_read,
> - .write = mtty_write,
> - .ioctl = mtty_ioctl,
> };
>
> static void mtty_device_release(struct device *dev)
> --
> 2.19.1