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Date:   Wed, 23 Oct 2019 15:57:28 -0600
From:   Alex Williamson <alex.williamson@redhat.com>
To:     Jason Wang <jasowang@redhat.com>
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Subject: Re: [PATCH V5 4/6] mdev: introduce virtio device and its device ops
Message-ID: <20191023155728.2a55bc71@x1.home>
In-Reply-To: <20191023130752.18980-5-jasowang@redhat.com>
References: <20191023130752.18980-1-jasowang@redhat.com>
        <20191023130752.18980-5-jasowang@redhat.com>
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On Wed, 23 Oct 2019 21:07:50 +0800
Jason Wang <jasowang@redhat.com> wrote:

> This patch implements basic support for mdev driver that supports
> virtio transport for kernel virtio driver.
>=20
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  drivers/vfio/mdev/mdev_core.c    |  20 ++++
>  drivers/vfio/mdev/mdev_private.h |   2 +
>  include/linux/mdev.h             |   6 ++
>  include/linux/virtio_mdev_ops.h  | 159 +++++++++++++++++++++++++++++++
>  4 files changed, 187 insertions(+)
>  create mode 100644 include/linux/virtio_mdev_ops.h
>=20
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.=
c
> index 555bd61d8c38..9b00c3513120 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -76,6 +76,26 @@ const struct vfio_mdev_device_ops *mdev_get_vfio_ops(s=
truct mdev_device *mdev)
>  }
>  EXPORT_SYMBOL(mdev_get_vfio_ops);
> =20
> +/* Specify the virtio device ops for the mdev device, this
> + * must be called during create() callback for virtio mdev device.
> + */
> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> +=09=09=09 const struct virtio_mdev_device_ops *virtio_ops)
> +{
> +=09mdev_set_class(mdev, MDEV_CLASS_ID_VIRTIO);
> +=09mdev->virtio_ops =3D virtio_ops;
> +}
> +EXPORT_SYMBOL(mdev_set_virtio_ops);
> +
> +/* Get the virtio device ops for the mdev device. */
> +const struct virtio_mdev_device_ops *
> +mdev_get_virtio_ops(struct mdev_device *mdev)
> +{
> +=09WARN_ON(mdev->class_id !=3D MDEV_CLASS_ID_VIRTIO);
> +=09return mdev->virtio_ops;
> +}
> +EXPORT_SYMBOL(mdev_get_virtio_ops);
> +
>  struct device *mdev_dev(struct mdev_device *mdev)
>  {
>  =09return &mdev->dev;
> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_pr=
ivate.h
> index 0770410ded2a..7b47890c34e7 100644
> --- a/drivers/vfio/mdev/mdev_private.h
> +++ b/drivers/vfio/mdev/mdev_private.h
> @@ -11,6 +11,7 @@
>  #define MDEV_PRIVATE_H
> =20
>  #include <linux/vfio_mdev_ops.h>
> +#include <linux/virtio_mdev_ops.h>
> =20
>  int  mdev_bus_register(void);
>  void mdev_bus_unregister(void);
> @@ -38,6 +39,7 @@ struct mdev_device {
>  =09u16 class_id;
>  =09union {
>  =09=09const struct vfio_mdev_device_ops *vfio_ops;
> +=09=09const struct virtio_mdev_device_ops *virtio_ops;
>  =09};
>  };
> =20
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index 4625f1a11014..9b69b0bbebfd 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -17,6 +17,7 @@
> =20
>  struct mdev_device;
>  struct vfio_mdev_device_ops;
> +struct virtio_mdev_device_ops;
> =20
>  /*
>   * Called by the parent device driver to set the device which represents
> @@ -112,6 +113,10 @@ void mdev_set_class(struct mdev_device *mdev, u16 id=
);
>  void mdev_set_vfio_ops(struct mdev_device *mdev,
>  =09=09       const struct vfio_mdev_device_ops *vfio_ops);
>  const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device =
*mdev);
> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> +=09=09=09 const struct virtio_mdev_device_ops *virtio_ops);
> +const struct virtio_mdev_device_ops *
> +mdev_get_virtio_ops(struct mdev_device *mdev);
> =20
>  extern struct bus_type mdev_bus_type;
> =20
> @@ -127,6 +132,7 @@ struct mdev_device *mdev_from_dev(struct device *dev)=
;
> =20
>  enum {
>  =09MDEV_CLASS_ID_VFIO =3D 1,
> +=09MDEV_CLASS_ID_VIRTIO =3D 2,
>  =09/* New entries must be added here */
>  };
> =20
> diff --git a/include/linux/virtio_mdev_ops.h b/include/linux/virtio_mdev_=
ops.h
> new file mode 100644
> index 000000000000..d417b41f2845
> --- /dev/null
> +++ b/include/linux/virtio_mdev_ops.h
> @@ -0,0 +1,159 @@
> +/* 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=09=09"virtio-mdev"
> +#define VIRTIO_MDEV_F_VERSION_1 0x1
> +
> +struct virtio_mdev_callback {
> +=09irqreturn_t (*callback)(void *data);
> +=09void *private;
> +};
> +
> +/**
> + * struct vfio_mdev_device_ops - Structure to be registered for each
> + * mdev device to register the device for virtio/vhost drivers.
> + *
> + * The device ops that is supported by VIRTIO_MDEV_F_VERSION_1, the
> + * callbacks are mandatory unless explicity mentioned.

If the version of the callbacks is returned by a callback within the
structure defined by the version... isn't that a bit circular?  This
seems redundant to me versus the class id.  The fact that the parent
driver defines the device as MDEV_CLASS_ID_VIRTIO should tell us this
already.  If it was incremented, we'd need an MDEV_CLASS_ID_VIRTIOv2,
which the virtio-mdev bus driver could add to its id table and handle
differently.

> + *
> + * @set_vq_address:=09=09Set the address of virtqueue
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@idx: virtqueue index
> + *=09=09=09=09@desc_area: address of desc area
> + *=09=09=09=09@driver_area: address of driver area
> + *=09=09=09=09@device_area: address of device area
> + *=09=09=09=09Returns integer: success (0) or error (< 0)
> + * @set_vq_num:=09=09=09Set the size of virtqueue
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@idx: virtqueue index
> + *=09=09=09=09@num: the size of virtqueue
> + * @kick_vq:=09=09=09Kick the virtqueue
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@idx: virtqueue index
> + * @set_vq_cb:=09=09=09Set the interrupt callback function for
> + *=09=09=09=09a virtqueue
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@idx: virtqueue index
> + *=09=09=09=09@cb: virtio-mdev interrupt callback structure
> + * @set_vq_ready:=09=09Set ready status for a virtqueue
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@idx: virtqueue index
> + *=09=09=09=09@ready: ready (true) not ready(false)
> + * @get_vq_ready:=09=09Get ready status for a virtqueue
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@idx: virtqueue index
> + *=09=09=09=09Returns boolean: ready (true) or not (false)
> + * @set_vq_state:=09=09Set the state for a virtqueue
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@idx: virtqueue index
> + *=09=09=09=09@state: virtqueue state (last_avail_idx)
> + *=09=09=09=09Returns integer: success (0) or error (< 0)
> + * @get_vq_state:=09=09Get the state for a virtqueue
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@idx: virtqueue index
> + *=09=09=09=09Returns virtqueue state (last_avail_idx)
> + * @get_vq_align:=09=09Get the virtqueue align requirement
> + *=09=09=09=09for the device
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09Returns virtqueue algin requirement
> + * @get_features:=09=09Get virtio features supported by the device
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09Returns the virtio features support by the
> + *=09=09=09=09device
> + * @get_features:=09=09Set virtio features supported by the driver
       ^ s/g/s/

Thanks,
Alex


> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@features: feature support by the driver
> + *=09=09=09=09Returns integer: success (0) or error (< 0)
> + * @set_config_cb:=09=09Set the config interrupt callback
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@cb: virtio-mdev interrupt callback structure
> + * @get_vq_num_max:=09=09Get the max size of virtqueue
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09Returns u16: max size of virtqueue
> + * @get_device_id:=09=09Get virtio device id
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09Returns u32: virtio device id
> + * @get_vendor_id:=09=09Get id for the vendor that provides this device
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09Returns u32: virtio vendor id
> + * @get_status:=09=09=09Get the device status
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09Returns u8: virtio device status
> + * @set_status:=09=09=09Set the device status
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@status: virtio device status
> + * @get_config:=09=09=09Read from device specific configuration space
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@offset: offset from the beginning of
> + *=09=09=09=09configuration space
> + *=09=09=09=09@buf: buffer used to read to
> + *=09=09=09=09@len: the length to read from
> + *=09=09=09=09configration space
> + * @set_config:=09=09=09Write to device specific configuration space
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09@offset: offset from the beginning of
> + *=09=09=09=09configuration space
> + *=09=09=09=09@buf: buffer used to write from
> + *=09=09=09=09@len: the length to write to
> + *=09=09=09=09configration space
> + * @get_mdev_features:=09=09Get a set of bits that demonstrate
> + *=09=09=09=09thecapability of the mdev device. New
> + *=09=09=09=09features bits must be added when
> + *=09=09=09=09introducing new device ops.
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09Returns the mdev features (API) support by
> + *=09=09=09=09the device.
> + * @get_generation:=09=09Get device config generaton (optionally)
> + *=09=09=09=09@mdev: mediated device
> + *=09=09=09=09Returns u32: device generation
> + */
> +struct virtio_mdev_device_ops {
> +=09/* Virtqueue ops */
> +=09int (*set_vq_address)(struct mdev_device *mdev,
> +=09=09=09      u16 idx, u64 desc_area, u64 driver_area,
> +=09=09=09      u64 device_area);
> +=09void (*set_vq_num)(struct mdev_device *mdev, u16 idx, u32 num);
> +=09void (*kick_vq)(struct mdev_device *mdev, u16 idx);
> +=09void (*set_vq_cb)(struct mdev_device *mdev, u16 idx,
> +=09=09=09  struct virtio_mdev_callback *cb);
> +=09void (*set_vq_ready)(struct mdev_device *mdev, u16 idx, bool ready);
> +=09bool (*get_vq_ready)(struct mdev_device *mdev, u16 idx);
> +=09int (*set_vq_state)(struct mdev_device *mdev, u16 idx, u64 state);
> +=09u64 (*get_vq_state)(struct mdev_device *mdev, u16 idx);
> +
> +=09/* Virtio device ops */
> +=09u16 (*get_vq_align)(struct mdev_device *mdev);
> +=09u64 (*get_features)(struct mdev_device *mdev);
> +=09int (*set_features)(struct mdev_device *mdev, u64 features);
> +=09void (*set_config_cb)(struct mdev_device *mdev,
> +=09=09=09      struct virtio_mdev_callback *cb);
> +=09u16 (*get_vq_num_max)(struct mdev_device *mdev);
> +=09u32 (*get_device_id)(struct mdev_device *mdev);
> +=09u32 (*get_vendor_id)(struct mdev_device *mdev);
> +=09u8 (*get_status)(struct mdev_device *mdev);
> +=09void (*set_status)(struct mdev_device *mdev, u8 status);
> +=09void (*get_config)(struct mdev_device *mdev, unsigned int offset,
> +=09=09=09   void *buf, unsigned int len);
> +=09void (*set_config)(struct mdev_device *mdev, unsigned int offset,
> +=09=09=09   const void *buf, unsigned int len);
> +=09u32 (*get_generation)(struct mdev_device *mdev);
> +
> +=09/* Mdev device ops */
> +=09u64 (*get_mdev_features)(struct mdev_device *mdev);
> +};
> +
> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> +=09=09=09 const struct virtio_mdev_device_ops *virtio_ops);
> +
> +#endif