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    SubjectRe: [PATCH V4 4/6] mdev: introduce virtio device and its device ops
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    On 2019/10/18 下午5:46, Cornelia Huck wrote:
    > On Thu, 17 Oct 2019 18:48:34 +0800
    > Jason Wang <jasowang@redhat.com> wrote:
    >
    >> This patch implements basic support for mdev driver that supports
    >> virtio transport for kernel virtio driver.
    >>
    >> Signed-off-by: Jason Wang <jasowang@redhat.com>
    >> ---
    >> drivers/vfio/mdev/mdev_core.c | 12 +++
    >> include/linux/mdev.h | 4 +
    >> include/linux/virtio_mdev.h | 151 ++++++++++++++++++++++++++++++++++
    >> 3 files changed, 167 insertions(+)
    >> create mode 100644 include/linux/virtio_mdev.h
    >>
    >> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
    >> index d0f3113c8071..5834f6b7c7a5 100644
    >> --- a/drivers/vfio/mdev/mdev_core.c
    >> +++ b/drivers/vfio/mdev/mdev_core.c
    >> @@ -57,6 +57,18 @@ void mdev_set_vfio_ops(struct mdev_device *mdev,
    >> }
    >> EXPORT_SYMBOL(mdev_set_vfio_ops);
    >>
    >> +/* Specify the virtio device ops for the mdev device, this
    >> + * must be called during create() callback for virtio mdev device.
    >> + */
    > Change this as for the vfio comment (last patch?)


    Ok.


    >
    >> +void mdev_set_virtio_ops(struct mdev_device *mdev,
    >> + const struct virtio_mdev_device_ops *virtio_ops)
    >> +{
    >> + BUG_ON(mdev->class_id);
    > s/BUG_ON/WARN_ON/


    Yes.


    >
    >> + mdev->class_id = MDEV_CLASS_ID_VIRTIO;
    >> + mdev->device_ops = virtio_ops;
    >> +}
    >> +EXPORT_SYMBOL(mdev_set_virtio_ops);
    >> +
    >> const void *mdev_get_dev_ops(struct mdev_device *mdev)
    >> {
    >> return mdev->device_ops;
    > (...)
    >
    >> diff --git a/include/linux/virtio_mdev.h b/include/linux/virtio_mdev.h
    >> new file mode 100644
    >> index 000000000000..b965b50f9b24
    >> --- /dev/null
    >> +++ b/include/linux/virtio_mdev.h
    >> @@ -0,0 +1,151 @@
    >> +/* 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_F_VERSION_1 0x1
    >> +
    >> +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)
    > Probably dumb question (have not read the next patches yet): Is this
    > agnostic regarding split or packed queues?


    Yes, it is to and to be more obvious, I use the terminology from recent
    spec.


    >
    >> + * @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 interrupt callback 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 virtio features support by the
    >> + * device
    >> + * @get_features: Set virtio features supported by the driver
    > s/get_features/set_features/


    Will fix.


    >
    >> + * @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_vq_num_max: Get the max size of virtqueue
    >> + * @mdev: mediated device
    >> + * Returns u16: max size of virtqueue
    >> + * @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
    > How is the vendor id defined? As for normal virtio-pci devices?


    The vendor that provides this device. So something like this

    I notice that MMIO also had this so it looks to me it's not pci specific.


    >
    >> + * @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 configuration space
    >> + * @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 configuration 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_mdev_features: Get the feature of virtio mdev device
    >> + * @mdev: mediated device
    >> + * Returns the mdev features (API) support by
    >> + * the device.
    > What kind of 'features' are supposed to go in there? Are these bits,
    > like you defined for VIRTIO_MDEV_F_VERSION_1 above?


    It's the API or mdev features other than virtio features. It could be
    used by driver to determine the capability of the mdev device. Besides
    _F_VERSION_1, we may add dirty page tracking etc which means we need new
    device ops.


    >
    >> + * @get_generation: Get device generaton
    >> + * @mdev: mediated device
    >> + * Returns u32: device generation
    > Is that callback mandatory?


    I think so, it's hard to emulate that completely in virtio-mdev transport.

    Thanks


    >
    >> + */
    >> +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_vq_num_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);
    >> + u64 (*get_mdev_features)(struct mdev_device *mdev);
    >> + u32 (*get_generation)(struct mdev_device *mdev);
    >> +};
    >> +
    >> +void mdev_set_virtio_ops(struct mdev_device *mdev,
    >> + const struct virtio_mdev_device_ops *virtio_ops);
    >> +
    >> +#endif

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