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

Jason Wang
2019-10-21T06:02:53Z

On 2019/10/21 上午7:41, Parav Pandit wrote:
>
>> -----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-
>> kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; intel-
>> gfx@lists.freedesktop.org; intel-gvt-dev@lists.freedesktop.org;
>> kwankhede@nvidia.com; alex.williamson@redhat.com; mst@redhat.com;
>> tiwei.bie@intel.com
>> Cc: virtualization@lists.linux-foundation.org; netdev@vger.kernel.org;
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>> rob.miller@broadcom.com; xiao.w.wang@intel.com;
>> haotian.wang@sifive.com; zhenyuw@linux.intel.com; zhi.a.wang@intel.com;
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>> borntraeger@de.ibm.com; akrowiak@linux.ibm.com; freude@linux.ibm.com;
>> 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.

That sounds good, will do.

>> +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.

Ok.

>> };
>>
>> #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.

Sure.

>
>> 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.

Ok.

>
>> 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

Will do.

Thanks

>
>> 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