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Date: Thu, 15 Dec 2016 06:56:15 +0200
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Jarno Rajahalme <jarno@....org>
Cc: netdev@...r.kernel.org, james.zhangming@...wei.com,
vyasevic@...hat.com, ailan@...hat.com
Subject: Re: [RFC PATCH net-next] virtio_net: Support UDP Tunnel offloads.
On Thu, Nov 17, 2016 at 03:01:57PM -0800, Jarno Rajahalme wrote:
> This patch is a proof-of-concept I did a few months ago for UDP tunnel
> offload support in virtio_net interface, and rebased on to the current
> net-next.
>
> Real implementation needs to extend the virtio_net header rather than
> piggy-backing on existing fields. Inner MAC length (or inner network
> offset) also needs to be passed as a new field. Control plane (QEMU)
> also needs to be updated.
>
> All testing was done using Geneve, but this should work for all UDP
> tunnels the same.
>
> Signed-off-by: Jarno Rajahalme <jarno@....org>
Vlad, could you comment on this pls?
> ---
> drivers/net/tun.c | 7 ++++-
> drivers/net/virtio_net.c | 16 +++++++---
> include/linux/skbuff.h | 5 ++++
> include/linux/virtio_net.h | 66 ++++++++++++++++++++++++++++++-----------
> include/uapi/linux/virtio_net.h | 7 +++++
> 5 files changed, 78 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 1588469..36f3219 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -198,7 +198,9 @@ struct tun_struct {
> struct net_device *dev;
> netdev_features_t set_features;
> #define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
> - NETIF_F_TSO6|NETIF_F_UFO)
> + NETIF_F_TSO6|NETIF_F_UFO|NETIF_F_GSO_UDP_TUNNEL| \
> + NETIF_F_GSO_UDP_TUNNEL_CSUM| \
> + NETIF_F_GSO_TUNNEL_REMCSUM)
>
> int align;
> int vnet_hdr_sz;
> @@ -1877,6 +1879,9 @@ static int set_offload(struct tun_struct *tun, unsigned long arg)
>
> if (arg & TUN_F_UFO) {
> features |= NETIF_F_UFO;
> +#if 1
> + features |= NETIF_F_GSO_UDP_TUNNEL|NETIF_F_GSO_UDP_TUNNEL_CSUM|NETIF_F_GSO_TUNNEL_REMCSUM;
> +#endif
> arg &= ~TUN_F_UFO;
> }
> }
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index ca5239a..eb8d887 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1789,7 +1789,10 @@ static int virtnet_probe(struct virtio_device *vdev)
>
> if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
> dev->hw_features |= NETIF_F_TSO | NETIF_F_UFO
> - | NETIF_F_TSO_ECN | NETIF_F_TSO6;
> + | NETIF_F_TSO_ECN | NETIF_F_TSO6
> + | NETIF_F_GSO_UDP_TUNNEL
> + | NETIF_F_GSO_UDP_TUNNEL_CSUM
> + | NETIF_F_GSO_TUNNEL_REMCSUM;
> }
> /* Individual feature bits: what can host handle? */
> if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO4))
> @@ -1798,13 +1801,18 @@ static int virtnet_probe(struct virtio_device *vdev)
> dev->hw_features |= NETIF_F_TSO6;
> if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
> dev->hw_features |= NETIF_F_TSO_ECN;
> - if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UFO))
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UFO)) {
> dev->hw_features |= NETIF_F_UFO;
> -
> +#if 1
> + dev->hw_features |= NETIF_F_GSO_UDP_TUNNEL;
> + dev->hw_features |= NETIF_F_GSO_UDP_TUNNEL_CSUM;
> + dev->hw_features |= NETIF_F_GSO_TUNNEL_REMCSUM;
> +#endif
> + }
> dev->features |= NETIF_F_GSO_ROBUST;
>
> if (gso)
> - dev->features |= dev->hw_features & (NETIF_F_ALL_TSO|NETIF_F_UFO);
> + dev->features |= dev->hw_features & (NETIF_F_ALL_TSO|NETIF_F_UFO|NETIF_F_GSO_UDP_TUNNEL|NETIF_F_GSO_UDP_TUNNEL_CSUM|NETIF_F_GSO_TUNNEL_REMCSUM);
> /* (!csum && gso) case will be fixed by register_netdev() */
> }
> if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index a4aeeca..992ad30 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2115,6 +2115,11 @@ static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
> return skb->head + skb->inner_mac_header;
> }
>
> +static inline int skb_inner_mac_offset(const struct sk_buff *skb)
> +{
> + return skb_inner_mac_header(skb) - skb->data;
> +}
> +
> static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
> {
> skb->inner_mac_header = skb->data - skb->head;
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index 1c912f8..17384d1 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -8,10 +8,19 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
> const struct virtio_net_hdr *hdr,
> bool little_endian)
> {
> - unsigned short gso_type = 0;
> + u16 start = __virtio16_to_cpu(little_endian, hdr->csum_start);
> +
> + if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
> + u16 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
> +
> + if (!skb_partial_csum_set(skb, start, off))
> + return -EINVAL;
> + }
>
> if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> - switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
> + unsigned short gso_type = 0;
> +
> + switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_FLAGS) {
> case VIRTIO_NET_HDR_GSO_TCPV4:
> gso_type = SKB_GSO_TCPV4;
> break;
> @@ -27,23 +36,28 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
>
> if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
> gso_type |= SKB_GSO_TCP_ECN;
> + if (hdr->gso_type & VIRTIO_NET_HDR_GSO_UDP_TUNNEL)
> + gso_type |= SKB_GSO_UDP_TUNNEL;
> + if (hdr->gso_type & VIRTIO_NET_HDR_GSO_UDP_TUNNEL_CSUM)
> + gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
> + if (hdr->gso_type & VIRTIO_NET_HDR_GSO_TUNNEL_REMCSUM) {
> + gso_type |= SKB_GSO_TUNNEL_REMCSUM;
> + skb->remcsum_offload = true;
> + }
> + if (gso_type & (SKB_GSO_UDP_TUNNEL | SKB_GSO_UDP_TUNNEL_CSUM)) {
> + u16 hdr_len = __virtio16_to_cpu(little_endian,
> + hdr->hdr_len);
> + skb->encapsulation = 1;
> + skb_set_inner_mac_header(skb, hdr_len);
> + skb_set_inner_network_header(skb, hdr_len + ETH_HLEN);
> + /* XXX: What if start is not set? */
> + skb_set_inner_transport_header(skb, start);
> + }
>
> if (hdr->gso_size == 0)
> return -EINVAL;
> - }
> -
> - if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
> - u16 start = __virtio16_to_cpu(little_endian, hdr->csum_start);
> - u16 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
> -
> - if (!skb_partial_csum_set(skb, start, off))
> - return -EINVAL;
> - }
> -
> - if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> - u16 gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size);
> -
> - skb_shinfo(skb)->gso_size = gso_size;
> + skb_shinfo(skb)->gso_size = __virtio16_to_cpu(little_endian,
> + hdr->gso_size);
> skb_shinfo(skb)->gso_type = gso_type;
>
> /* Header must be checked, and gso_segs computed. */
> @@ -64,8 +78,8 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
> struct skb_shared_info *sinfo = skb_shinfo(skb);
>
> /* This is a hint as to how much should be linear. */
> - hdr->hdr_len = __cpu_to_virtio16(little_endian,
> - skb_headlen(skb));
> + u16 hdr_len = skb_headlen(skb);
> +
> hdr->gso_size = __cpu_to_virtio16(little_endian,
> sinfo->gso_size);
> if (sinfo->gso_type & SKB_GSO_TCPV4)
> @@ -78,6 +92,22 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
> return -EINVAL;
> if (sinfo->gso_type & SKB_GSO_TCP_ECN)
> hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
> + if (sinfo->gso_type & SKB_GSO_UDP_TUNNEL)
> + hdr->gso_type |= VIRTIO_NET_HDR_GSO_UDP_TUNNEL;
> + if (sinfo->gso_type & SKB_GSO_UDP_TUNNEL_CSUM)
> + hdr->gso_type |= VIRTIO_NET_HDR_GSO_UDP_TUNNEL_CSUM;
> + if (sinfo->gso_type & SKB_GSO_TUNNEL_REMCSUM)
> + hdr->gso_type |= VIRTIO_NET_HDR_GSO_TUNNEL_REMCSUM;
> +
> + if (sinfo->gso_type &
> + (SKB_GSO_UDP_TUNNEL | SKB_GSO_UDP_TUNNEL_CSUM))
> + /* For encapsulated packets 'hdr_len' is the offset to
> + * the beginning of the inner packet. This way the
> + * encapsulation can remain ignorant of the size of the
> + * UDP tunnel header.
> + */
> + hdr_len = skb_inner_mac_offset(skb);
> + hdr->hdr_len = __cpu_to_virtio16(little_endian, hdr_len);
> } else
> hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
>
> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
> index fc353b5..833950b 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -93,7 +93,14 @@ struct virtio_net_hdr_v1 {
> #define VIRTIO_NET_HDR_GSO_TCPV4 1 /* GSO frame, IPv4 TCP (TSO) */
> #define VIRTIO_NET_HDR_GSO_UDP 3 /* GSO frame, IPv4 UDP (UFO) */
> #define VIRTIO_NET_HDR_GSO_TCPV6 4 /* GSO frame, IPv6 TCP */
> +#define VIRTIO_NET_HDR_GSO_UDP_TUNNEL 0x10 /* GSO frame, UDP tunnel */
> +#define VIRTIO_NET_HDR_GSO_UDP_TUNNEL_CSUM 0x20 /* GSO frame, UDP tnl w CSUM */
> +#define VIRTIO_NET_HDR_GSO_TUNNEL_REMCSUM 0x40 /* TUNNEL with TSO & REMCSUM */
> #define VIRTIO_NET_HDR_GSO_ECN 0x80 /* TCP has ECN set */
> +#define VIRTIO_NET_HDR_GSO_FLAGS (VIRTIO_NET_HDR_GSO_UDP_TUNNEL | \
> + VIRTIO_NET_HDR_GSO_UDP_TUNNEL_CSUM | \
> + VIRTIO_NET_HDR_GSO_TUNNEL_REMCSUM | \
> + VIRTIO_NET_HDR_GSO_ECN)
> __u8 gso_type;
> __virtio16 hdr_len; /* Ethernet + IP + tcp/udp hdrs */
> __virtio16 gso_size; /* Bytes to append to hdr_len per frame */
> --
> 2.1.4
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