RE: [PATCH 2/6] mdev: introduce device specific ops

Parav Pandit
2019-09-23T22:59:08Z

> -----Original Message-----
> From: Jason Wang <jasowang@redhat.com>
> Sent: Monday, September 23, 2019 8:03 AM
> To: kvm@vger.kernel.org; linux-s390@vger.kernel.org; linux-
> kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; intel-
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> lingshan.zhu@intel.com; Ido Shamay <idos@mellanox.com>;
> eperezma@redhat.com; lulu@redhat.com; Parav Pandit
> <parav@mellanox.com>; Jason Wang <jasowang@redhat.com>
> Subject: [PATCH 2/6] 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.
> Follow the class id support by previous patch, this patch introduces device
> specific ops pointer inside parent ops which points to device specific ops (e.g
> vfio ops). This allows the future drivers like virtio-mdev to implement its own
> device specific ops.
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> .../driver-api/vfio-mediated-device.rst | 4 +-
> MAINTAINERS | 1 +
> drivers/gpu/drm/i915/gvt/kvmgt.c | 15 +++---
> drivers/s390/cio/vfio_ccw_ops.c | 15 ++++--
> drivers/s390/crypto/vfio_ap_ops.c | 11 ++--
> drivers/vfio/mdev/vfio_mdev.c | 31 ++++++-----
> include/linux/mdev.h | 36 ++-----------
> include/linux/vfio_mdev.h | 53 +++++++++++++++++++
> samples/vfio-mdev/mbochs.c | 17 +++---
> samples/vfio-mdev/mdpy.c | 17 +++---
> samples/vfio-mdev/mtty.c | 15 ++++--
> 11 files changed, 138 insertions(+), 77 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 0e052072e1d8..3ab00e48212f 100644
> --- a/Documentation/driver-api/vfio-mediated-device.rst
> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> @@ -152,7 +152,9 @@ 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:
> +The device specific callbacks are referred through device_ops pointer
> +in mdev_parent_ops. For vfio-mdev device, its callbacks in device_ops
> +are as follows:
>
> * open: open callback of mediated device
> * close: close callback of mediated device diff --git a/MAINTAINERS
> b/MAINTAINERS index b2326dece28e..89832b316500 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -17075,6 +17075,7 @@ 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 19d51a35f019..8ea86b1e69f1 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>
> @@ -1600,20 +1601,22 @@ 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 struct vfio_mdev_parent_ops intel_vfio_vgpu_ops = {

Naming it with _dev prefix as intel_vfio_vgpu_dev_ops is better to differentiate with parent_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,
> + .device_ops = &intel_vfio_vgpu_ops,
> +};
> +
> 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 246ff0f80944..02122bbc213e 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>
>
> @@ -574,11 +575,7 @@ 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_parent_ops vfio_mdev_ops = {
> .open = vfio_ccw_mdev_open,
> .release = vfio_ccw_mdev_release,
> .read = vfio_ccw_mdev_read,
> @@ -586,6 +583,14 @@ 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,
> + .device_ops = &vfio_mdev_ops,
> +};
> +
> int vfio_ccw_mdev_reg(struct subchannel *sch) {
> return mdev_register_vfio_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 7487fc39d2c5..4251becc7a6d 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>
>
> @@ -1280,15 +1281,19 @@ static ssize_t vfio_ap_mdev_ioctl(struct
> mdev_device *mdev,
> return ret;
> }
>
> +static const struct vfio_mdev_parent_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,
> + .device_ops = &vfio_mdev_ops,
> };
>
> int vfio_ap_mdev_register(void)
> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
> index fd2a4d9a3f26..d23c9f58c84f 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"
>
> @@ -25,15 +26,16 @@ static int vfio_mdev_open(void *device_data) {
> struct mdev_device *mdev = device_data;
> struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
> int ret;
>
> - if (unlikely(!parent->ops->open))
> + if (unlikely(!ops->open))
> return -EINVAL;
>
device_ops is optional and can be NULL for mdev devices which are not required to be mapped via vfio.
So please change to,

If (!ops || !ops->open)
return -EINVAL;

and rest of the below places.

> if (!try_module_get(THIS_MODULE))
> return -ENODEV;
>
> - ret = parent->ops->open(mdev);
> + ret = ops->open(mdev);
> if (ret)
> module_put(THIS_MODULE);
>
> @@ -44,9 +46,10 @@ static void vfio_mdev_release(void *device_data) {
> struct mdev_device *mdev = device_data;
> struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
>
> - if (likely(parent->ops->release))
> - parent->ops->release(mdev);
> + if (likely(ops->release))
> + ops->release(mdev);
>
> module_put(THIS_MODULE);
> }
> @@ -56,11 +59,12 @@ static long vfio_mdev_unlocked_ioctl(void
> *device_data, {
> struct mdev_device *mdev = device_data;
> struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
>
> - 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, @@ -68,11
> +72,12 @@ static ssize_t vfio_mdev_read(void *device_data, char __user *buf,
> {
> struct mdev_device *mdev = device_data;
> struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
>
> - 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, @@
> -80,22 +85,24 @@ static ssize_t vfio_mdev_write(void *device_data, const char
> __user *buf, {
> struct mdev_device *mdev = device_data;
> struct mdev_parent *parent = mdev->parent;
> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
>
> - 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_parent_ops *ops = parent->ops->device_ops;
>
> - 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
> 3ebae310f599..fa167bcb81e1 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -48,30 +48,8 @@ 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
> + * @device_ops: Device specific emulation callback.
> + *
> * Parent device that support mediated device should be registered with mdev
> * module with mdev_parent_ops structure.
> **/
> @@ -83,15 +61,7 @@ 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);
> + const void *device_ops;
> };
>
> /* interface for exporting mdev supported type attributes */ diff --git
> a/include/linux/vfio_mdev.h b/include/linux/vfio_mdev.h new file mode
> 100644 index 000000000000..0c1b34f98f5d
> --- /dev/null
> +++ b/include/linux/vfio_mdev.h
> @@ -0,0 +1,53 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * VFIO Mediated device definition
> + */
> +
> +#ifndef VFIO_MDEV_H
> +#define VFIO_MDEV_H
> +
> +#include <linux/types.h>
> +#include <linux/mdev.h>
> +
> +/**
> + * struct vfio_mdev_parent_ops - Structure to be registered for each
> + * parent 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_parent_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
> 71a4469be85d..107cc30d0f45 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>
> @@ -1418,12 +1419,7 @@ 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_parent_ops vfio_mdev_ops = {
> .open = mbochs_open,
> .release = mbochs_close,
> .read = mbochs_read,
> @@ -1432,6 +1428,15 @@ 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,
> + .device_ops = &vfio_mdev_ops,
> +};
> +
> 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
> d3029dd27d91..2cd2018a53f9 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"
> @@ -725,12 +726,7 @@ 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_parent_ops vfio_mdev_ops = {
> .open = mdpy_open,
> .release = mdpy_close,
> .read = mdpy_read,
> @@ -739,6 +735,15 @@ 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,
> + .device_ops = &vfio_mdev_ops,
> +};
> +
> 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
> 744c88a6b22c..e427425b5daf 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>
> @@ -1410,6 +1411,14 @@ static struct attribute_group *mdev_type_groups[]
> = {
> NULL,
> };
>
> +static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
> + .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,
> @@ -1417,11 +1426,7 @@ 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,
> + .device_ops = &vfio_mdev_ops,
> };
>
> static void mtty_device_release(struct device *dev)
> --
> 2.19.1