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SubjectRE: [PATCH V2 6/8] mdev: introduce virtio device and its device ops
Date
> From: Jason Wang [mailto:jasowang@redhat.com]
> Sent: Tuesday, September 24, 2019 9:54 PM
>
> This patch implements basic support for mdev driver that supports
> virtio transport for kernel virtio driver.
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> include/linux/mdev.h | 2 +
> include/linux/virtio_mdev.h | 145
> ++++++++++++++++++++++++++++++++++++
> 2 files changed, 147 insertions(+)
> create mode 100644 include/linux/virtio_mdev.h
>
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index 3414307311f1..73ac27b3b868 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -126,6 +126,8 @@ struct mdev_device *mdev_from_dev(struct device
> *dev);
>
> enum {
> MDEV_ID_VFIO = 1,
> + MDEV_ID_VIRTIO = 2,
> + MDEV_ID_VHOST = 3,
> /* New entries must be added here */
> };
>
> diff --git a/include/linux/virtio_mdev.h b/include/linux/virtio_mdev.h
> new file mode 100644
> index 000000000000..d1a40a739266
> --- /dev/null
> +++ b/include/linux/virtio_mdev.h
> @@ -0,0 +1,145 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Virtio mediated device driver
> + *
> + * Copyright 2019, Red Hat Corp.
> + * Author: Jason Wang <jasowang@redhat.com>
> + */
> +#ifndef _LINUX_VIRTIO_MDEV_H
> +#define _LINUX_VIRTIO_MDEV_H
> +
> +#include <linux/interrupt.h>
> +#include <linux/mdev.h>
> +#include <uapi/linux/vhost.h>
> +
> +#define VIRTIO_MDEV_DEVICE_API_STRING "virtio-mdev"
> +#define VIRTIO_MDEV_VERSION 0x1

Just be curious. is this version identical to virtio spec version that below
callbacks are created for, or just irrelevant?

> +
> +struct virtio_mdev_callback {
> + irqreturn_t (*callback)(void *data);
> + void *private;
> +};
> +
> +/**
> + * struct vfio_mdev_device_ops - Structure to be registered for each
> + * mdev device to register the device to virtio-mdev module.
> + *
> + * @set_vq_address: Set the address of virtqueue
> + * @mdev: mediated device
> + * @idx: virtqueue index
> + * @desc_area: address of desc area
> + * @driver_area: address of driver area
> + * @device_area: address of device area
> + * Returns integer: success (0) or error (< 0)
> + * @set_vq_num: Set the size of virtqueue
> + * @mdev: mediated device
> + * @idx: virtqueue index
> + * @num: the size of virtqueue
> + * @kick_vq: Kick the virtqueue
> + * @mdev: mediated device
> + * @idx: virtqueue index
> + * @set_vq_cb: Set the interrut calback function for
> + * a virtqueue
> + * @mdev: mediated device
> + * @idx: virtqueue index
> + * @cb: virtio-mdev interrupt callback
> structure
> + * @set_vq_ready: Set ready status for a virtqueue
> + * @mdev: mediated device
> + * @idx: virtqueue index
> + * @ready: ready (true) not ready(false)
> + * @get_vq_ready: Get ready status for a virtqueue
> + * @mdev: mediated device
> + * @idx: virtqueue index
> + * Returns boolean: ready (true) or not (false)
> + * @set_vq_state: Set the state for a virtqueue
> + * @mdev: mediated device
> + * @idx: virtqueue index
> + * @state: virtqueue state (last_avail_idx)
> + * Returns integer: success (0) or error (< 0)
> + * @get_vq_state: Get the state for a virtqueue
> + * @mdev: mediated device
> + * @idx: virtqueue index
> + * Returns virtqueue state (last_avail_idx)
> + * @get_vq_align: Get the virtqueue align requirement
> + * for the device
> + * @mdev: mediated device
> + * Returns virtqueue algin requirement
> + * @get_features: Get virtio features supported by the device
> + * @mdev: mediated device
> + * Returns the features support by the
> + * device
> + * @get_features: Set virtio features supported by the driver
> + * @mdev: mediated device
> + * @features: feature support by the driver
> + * Returns integer: success (0) or error (< 0)
> + * @set_config_cb: Set the config interrupt callback
> + * @mdev: mediated device
> + * @cb: virtio-mdev interrupt callback
> structure
> + * @get_device_id: Get virtio device id
> + * @mdev: mediated device
> + * Returns u32: virtio device id
> + * @get_vendor_id: Get virtio vendor id
> + * @mdev: mediated device
> + * Returns u32: virtio vendor id
> + * @get_status: Get the device status
> + * @mdev: mediated device
> + * Returns u8: virtio device status
> + * @set_status: Set the device status
> + * @mdev: mediated device
> + * @status: virtio device status
> + * @get_config: Read from device specific confiugration
> space

configuration (and similar typos downward)

> + * @mdev: mediated device
> + * @offset: offset from the beginning of
> + * configuration space
> + * @buf: buffer used to read to
> + * @len: the length to read from
> + * configration space
> + * @set_config: Write to device specific confiugration space
> + * @mdev: mediated device
> + * @offset: offset from the beginning of
> + * configuration space
> + * @buf: buffer used to write from
> + * @len: the length to write to
> + * configration space
> + * @get_version: Get the version of virtio mdev device
> + * @mdev: mediated device
> + * Returns integer: version of the device
> + * @get_generation: Get device generaton
> + * @mdev: mediated device
> + * Returns u32: device generation
> + */
> +struct virtio_mdev_device_ops {
> + /* Virtqueue ops */
> + int (*set_vq_address)(struct mdev_device *mdev,
> + u16 idx, u64 desc_area, u64 driver_area,
> + u64 device_area);
> + void (*set_vq_num)(struct mdev_device *mdev, u16 idx, u32 num);
> + void (*kick_vq)(struct mdev_device *mdev, u16 idx);
> + void (*set_vq_cb)(struct mdev_device *mdev, u16 idx,
> + struct virtio_mdev_callback *cb);
> + void (*set_vq_ready)(struct mdev_device *mdev, u16 idx, bool
> ready);
> + bool (*get_vq_ready)(struct mdev_device *mdev, u16 idx);
> + int (*set_vq_state)(struct mdev_device *mdev, u16 idx, u64 state);
> + u64 (*get_vq_state)(struct mdev_device *mdev, u16 idx);
> +
> + /* Device ops */
> + u16 (*get_vq_align)(struct mdev_device *mdev);
> + u64 (*get_features)(struct mdev_device *mdev);
> + int (*set_features)(struct mdev_device *mdev, u64 features);
> + void (*set_config_cb)(struct mdev_device *mdev,
> + struct virtio_mdev_callback *cb);
> + u16 (*get_queue_max)(struct mdev_device *mdev);
> + u32 (*get_device_id)(struct mdev_device *mdev);
> + u32 (*get_vendor_id)(struct mdev_device *mdev);
> + u8 (*get_status)(struct mdev_device *mdev);
> + void (*set_status)(struct mdev_device *mdev, u8 status);
> + void (*get_config)(struct mdev_device *mdev, unsigned int offset,
> + void *buf, unsigned int len);
> + void (*set_config)(struct mdev_device *mdev, unsigned int offset,
> + const void *buf, unsigned int len);
> + int (*get_version)(struct mdev_device *mdev);
> + u32 (*get_generation)(struct mdev_device *mdev);
> +};

I'm not sure how stable above ops are. Does it make sense if defining
just two callbacks here, e.g. vq_ctrl and device_ctrl, and then let the
vendor driver to handle specific ops in each category (similar to how
ioctl works)?

Thanks
Kevin

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