netdev - Re: [RFC] vhost_mdev: add network control vq support

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Date:   Tue, 29 Oct 2019 18:51:32 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Tiwei Bie <tiwei.bie@...el.com>, mst@...hat.com
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        dan.daly@...el.com, cunming.liang@...el.com,
        zhihong.wang@...el.com, lingshan.zhu@...el.com
Subject: Re: [RFC] vhost_mdev: add network control vq support


On 2019/10/29 下午6:17, Tiwei Bie wrote:
> This patch adds the network control vq support in vhost-mdev.
> A vhost-mdev specific op is introduced to allow parent drivers
> to handle the network control commands come from userspace.


Probably work for userspace driver but not kernel driver.


>
> Signed-off-by: Tiwei Bie <tiwei.bie@...el.com>
> ---
> This patch depends on below patch:
> https://lkml.org/lkml/2019/10/29/335
>
>  drivers/vhost/mdev.c             | 37 ++++++++++++++++++++++++++++++--
>  include/linux/virtio_mdev_ops.h  | 10 +++++++++
>  include/uapi/linux/vhost.h       |  7 ++++++
>  include/uapi/linux/vhost_types.h |  6 ++++++
>  4 files changed, 58 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vhost/mdev.c b/drivers/vhost/mdev.c
> index 35b2fb33e686..c9b3eaa77405 100644
> --- a/drivers/vhost/mdev.c
> +++ b/drivers/vhost/mdev.c
> @@ -47,6 +47,13 @@ enum {
>  		(1ULL << VIRTIO_NET_F_HOST_UFO) |
>  		(1ULL << VIRTIO_NET_F_MRG_RXBUF) |
>  		(1ULL << VIRTIO_NET_F_STATUS) |
> +		(1ULL << VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) |
> +		(1ULL << VIRTIO_NET_F_CTRL_VQ) |
> +		(1ULL << VIRTIO_NET_F_CTRL_RX) |
> +		(1ULL << VIRTIO_NET_F_CTRL_VLAN) |
> +		(1ULL << VIRTIO_NET_F_CTRL_RX_EXTRA) |
> +		(1ULL << VIRTIO_NET_F_GUEST_ANNOUNCE) |
> +		(1ULL << VIRTIO_NET_F_CTRL_MAC_ADDR) |
>  		(1ULL << VIRTIO_NET_F_SPEED_DUPLEX),
>  };
>  
> @@ -362,6 +369,29 @@ static long vhost_mdev_vring_ioctl(struct vhost_mdev *m, unsigned int cmd,
>  	return r;
>  }
>  
> +/*
> + * Device specific (e.g. network) ioctls.
> + */
> +static long vhost_mdev_dev_ioctl(struct vhost_mdev *m, unsigned int cmd,
> +				 void __user *argp)
> +{
> +	struct mdev_device *mdev = m->mdev;
> +	const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
> +
> +	switch (m->virtio_id) {
> +	case VIRTIO_ID_NET:
> +		switch (cmd) {
> +		case VHOST_MDEV_NET_CTRL:
> +			if (!ops->net.ctrl)
> +				return -ENOTSUPP;
> +			return ops->net.ctrl(mdev, argp);
> +		}
> +		break;
> +	}
> +
> +	return -ENOIOCTLCMD;
> +}


As you comment above, then vhost-mdev need device specific stuffs.


> +
>  static int vhost_mdev_open(void *device_data)
>  {
>  	struct vhost_mdev *m = device_data;
> @@ -460,8 +490,11 @@ static long vhost_mdev_unlocked_ioctl(void *device_data,
>  		 * VHOST_SET_LOG_FD are not used yet.
>  		 */
>  		r = vhost_dev_ioctl(&m->dev, cmd, argp);
> -		if (r == -ENOIOCTLCMD)
> -			r = vhost_mdev_vring_ioctl(m, cmd, argp);
> +		if (r == -ENOIOCTLCMD) {
> +			r = vhost_mdev_dev_ioctl(m, cmd, argp);
> +			if (r == -ENOIOCTLCMD)
> +				r = vhost_mdev_vring_ioctl(m, cmd, argp);
> +		}
>  	}
>  
>  	mutex_unlock(&m->mutex);
> diff --git a/include/linux/virtio_mdev_ops.h b/include/linux/virtio_mdev_ops.h
> index d417b41f2845..622861804ebd 100644
> --- a/include/linux/virtio_mdev_ops.h
> +++ b/include/linux/virtio_mdev_ops.h
> @@ -20,6 +20,8 @@ struct virtio_mdev_callback {
>  	void *private;
>  };
>  
> +struct vhost_mdev_net_ctrl;
> +
>  /**
>   * struct vfio_mdev_device_ops - Structure to be registered for each
>   * mdev device to register the device for virtio/vhost drivers.
> @@ -151,6 +153,14 @@ struct virtio_mdev_device_ops {
>  
>  	/* Mdev device ops */
>  	u64 (*get_mdev_features)(struct mdev_device *mdev);
> +
> +	/* Vhost-mdev (MDEV_CLASS_ID_VHOST) specific ops */
> +	union {
> +		struct {
> +			int (*ctrl)(struct mdev_device *mdev,
> +				    struct vhost_mdev_net_ctrl __user *ctrl);
> +		} net;
> +	};


And so did device_ops. I still think we'd try out best to avoid such thing.

Thanks


>  };
>  
>  void mdev_set_virtio_ops(struct mdev_device *mdev,
> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
> index 061a2824a1b3..3693b2cba0c4 100644
> --- a/include/uapi/linux/vhost.h
> +++ b/include/uapi/linux/vhost.h
> @@ -134,4 +134,11 @@
>  /* Get the max ring size. */
>  #define VHOST_MDEV_GET_VRING_NUM	_IOR(VHOST_VIRTIO, 0x76, __u16)
>  
> +/* VHOST_MDEV device specific defines */
> +
> +/* Send virtio-net commands. The commands follow the same definition
> + * of the virtio-net commands defined in virtio-spec.
> + */
> +#define VHOST_MDEV_NET_CTRL		_IOW(VHOST_VIRTIO, 0x77, struct vhost_mdev_net_ctrl *)
> +
>  #endif
> diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h
> index 7b105d0b2fb9..e76b4d8e35e5 100644
> --- a/include/uapi/linux/vhost_types.h
> +++ b/include/uapi/linux/vhost_types.h
> @@ -127,6 +127,12 @@ struct vhost_mdev_config {
>  	__u8 buf[0];
>  };
>  
> +struct vhost_mdev_net_ctrl {
> +	__u8 class;
> +	__u8 cmd;
> +	__u8 cmd_data[0];
> +} __attribute__((packed));
> +
>  /* Feature bits */
>  /* Log all write descriptors. Can be changed while device is active. */
>  #define VHOST_F_LOG_ALL 26