Re: [PATCH RFC (resend) net-next 5/6] virtio-net: Add support for vlan acceleration vnet header extension.

["Michael S. Tsirkin" <mst@redhat.com>]

On Sat, Apr 15, 2017 at 12:38:17PM -0400, Vladislav Yasevich wrote:
> This extension allows us to pass vlan ID and vlan protocol data to the
> host hypervisor as part of the vnet header and lets us take advantage
> of HW accelerated vlan tagging in the host.  It requires support in the
> host to negotiate the feature.  When the extension is enabled, the
> virtio device will enabled HW accelerated vlan features.
> 
> Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>

Performance data will be required to justify this.


> ---
>  drivers/net/virtio_net.c        | 17 ++++++++++++++++-
>  include/linux/virtio_net.h      | 17 +++++++++++++++++
>  include/uapi/linux/virtio_net.h |  7 +++++++
>  3 files changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 18eb0dd..696ef4a 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -182,6 +182,7 @@ struct virtio_net_hdr_max {
>  	struct virtio_net_hdr_mrg_rxbuf hdr;
>  	struct virtio_net_ext_hdr ext_hdr;
>  	struct virtio_net_ext_ip6frag ip6f_ext;
> +	struct virtio_net_ext_vlan vlan_ext;
>  };
>  
>  static inline u8 padded_vnet_hdr(struct virtnet_info *vi)
> @@ -2276,6 +2277,11 @@ static void virtnet_init_extensions(struct virtio_device *vdev)
>  		vi->hdr_len += sizeof(u32);
>  		vi->ext_mask |= VIRTIO_NET_EXT_F_IP6FRAG;
>  	}
> +
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_VLAN_OFFLOAD)) {
> +		vi->hdr_len += sizeof(struct virtio_net_ext_vlan);
> +		vi->ext_mask |= VIRTIO_NET_EXT_F_VLAN;
> +	}
>  }
>  
>  #define MIN_MTU ETH_MIN_MTU
> @@ -2352,6 +2358,14 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
>  		dev->features |= NETIF_F_RXCSUM;
>  
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_VLAN_OFFLOAD)) {
> +		dev->features |= NETIF_F_HW_VLAN_CTAG_TX |
> +				 NETIF_F_HW_VLAN_CTAG_RX |
> +				 NETIF_F_HW_VLAN_STAG_TX |
> +				 NETIF_F_HW_VLAN_STAG_RX;
> +	}
> +
> +
>  	dev->vlan_features = dev->features;
>  
>  	/* MTU range: 68 - 65535 */
> @@ -2395,7 +2409,8 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
>  		vi->mergeable_rx_bufs = true;
>  
> -	if (virtio_has_feature(vdev, VIRTIO_NET_F_IP6_FRAGID))
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_IP6_FRAGID) ||
> +	    virtio_has_feature(vdev, VIRTIO_NET_F_VLAN_OFFLOAD))
>  		vi->hdr_ext = true;
>  
>  	if (vi->hdr_ext)
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index 3b259dc..e790191 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -113,6 +113,14 @@ static inline int virtio_net_ext_to_skb(struct sk_buff *skb,
>  		ptr += sizeof(struct virtio_net_ext_ip6frag);
>  	}
>  
> +	if (ext->flags & VIRTIO_NET_EXT_F_VLAN) {
> +		struct virtio_net_ext_vlan *vhdr =
> +					(struct virtio_net_ext_vlan *)ptr;
> +
> +		__vlan_hwaccel_put_tag(skb, vhdr->vlan_proto, vhdr->vlan_tci);
> +		ptr += sizeof(struct virtio_net_ext_vlan);
> +	}
> +
>  	return 0;
>  }
>  
> @@ -130,6 +138,15 @@ static inline int virtio_net_ext_from_skb(const struct sk_buff *skb,
>  		ext->flags |= VIRTIO_NET_EXT_F_IP6FRAG;
>  	}
>  
> +	if (ext_mask & VIRTIO_NET_EXT_F_VLAN && skb_vlan_tag_present(skb)) {
> +		struct virtio_net_ext_vlan *vhdr =
> +					(struct virtio_net_ext_vlan *)ptr;
> +
> +		vlan_get_tag(skb, &vhdr->vlan_tci);
> +		vhdr->vlan_proto = skb->vlan_proto;
> +		ext->flags |= VIRTIO_NET_EXT_F_VLAN;
> +	}
> +
>  	return 0;
>  }
>  #endif /* _LINUX_VIRTIO_NET_H */
> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
> index eac8d94..6125de7 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -57,6 +57,7 @@
>  					 * Steering */
>  #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
>  #define VIRTIO_NET_F_IP6_FRAGID    24	/* Host supports VLAN accleration */
> +#define VIRTIO_NET_F_VLAN_OFFLOAD 25	/* Host supports VLAN accleration */
>  
>  #ifndef VIRTIO_NET_NO_LEGACY
>  #define VIRTIO_NET_F_GSO	6	/* Host handles pkts w/ any GSO type */
> @@ -111,6 +112,7 @@ struct virtio_net_hdr_v1 {
>   */
>  struct virtio_net_ext_hdr {
>  #define VIRTIO_NET_EXT_F_IP6FRAG	(1<<0)
> +#define VIRTIO_NET_EXT_F_VLAN		(1<<1)
>  	__u32 flags;
>  	__u8 extensions[];
>  };
> @@ -120,6 +122,11 @@ struct virtio_net_ext_ip6frag {
>  	__be32 frag_id;
>  };
>  
> +struct virtio_net_ext_vlan {
> +	__be16 vlan_tci;
> +	__be16 vlan_proto;
> +};
> +
>  #ifndef VIRTIO_NET_NO_LEGACY
>  /* This header comes first in the scatter-gather list.
>   * For legacy virtio, if VIRTIO_F_ANY_LAYOUT is not negotiated, it must
> -- 
> 2.7.4