vxlan: Remote checksum offload
Add support for remote checksum offload in VXLAN. This uses a
reserved bit to indicate that RCO is being done, and uses the low order
reserved eight bits of the VNI to hold the start and offset values in a
compressed manner.
Start is encoded in the low order seven bits of VNI. This is start >> 1
so that the checksum start offset is 0-254 using even values only.
Checksum offset (transport checksum field) is indicated in the high
order bit in the low order byte of the VNI. If the bit is set, the
checksum field is for UDP (so offset = start + 6), else checksum
field is for TCP (so offset = start + 16). Only TCP and UDP are
supported in this implementation.
Remote checksum offload for VXLAN is described in:
https://tools.ietf.org/html/draft-herbert-vxlan-rco-00
Tested by running 200 TCP_STREAM connections with VXLAN (over IPv4).
With UDP checksums and Remote Checksum Offload
IPv4
Client
11.84% CPU utilization
Server
12.96% CPU utilization
9197 Mbps
IPv6
Client
12.46% CPU utilization
Server
14.48% CPU utilization
8963 Mbps
With UDP checksums, no remote checksum offload
IPv4
Client
15.67% CPU utilization
Server
14.83% CPU utilization
9094 Mbps
IPv6
Client
16.21% CPU utilization
Server
14.32% CPU utilization
9058 Mbps
No UDP checksums
IPv4
Client
15.03% CPU utilization
Server
23.09% CPU utilization
9089 Mbps
IPv6
Client
16.18% CPU utilization
Server
26.57% CPU utilization
8954 Mbps
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 5c56a3f..99df0d7 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -539,6 +539,46 @@
return 1;
}
+static struct vxlanhdr *vxlan_gro_remcsum(struct sk_buff *skb,
+ unsigned int off,
+ struct vxlanhdr *vh, size_t hdrlen,
+ u32 data)
+{
+ size_t start, offset, plen;
+ __wsum delta;
+
+ if (skb->remcsum_offload)
+ return vh;
+
+ if (!NAPI_GRO_CB(skb)->csum_valid)
+ return NULL;
+
+ start = (data & VXLAN_RCO_MASK) << VXLAN_RCO_SHIFT;
+ offset = start + ((data & VXLAN_RCO_UDP) ?
+ offsetof(struct udphdr, check) :
+ offsetof(struct tcphdr, check));
+
+ plen = hdrlen + offset + sizeof(u16);
+
+ /* Pull checksum that will be written */
+ if (skb_gro_header_hard(skb, off + plen)) {
+ vh = skb_gro_header_slow(skb, off + plen, off);
+ if (!vh)
+ return NULL;
+ }
+
+ delta = remcsum_adjust((void *)vh + hdrlen,
+ NAPI_GRO_CB(skb)->csum, start, offset);
+
+ /* Adjust skb->csum since we changed the packet */
+ skb->csum = csum_add(skb->csum, delta);
+ NAPI_GRO_CB(skb)->csum = csum_add(NAPI_GRO_CB(skb)->csum, delta);
+
+ skb->remcsum_offload = 1;
+
+ return vh;
+}
+
static struct sk_buff **vxlan_gro_receive(struct sk_buff **head,
struct sk_buff *skb,
struct udp_offload *uoff)
@@ -547,6 +587,9 @@
struct vxlanhdr *vh, *vh2;
unsigned int hlen, off_vx;
int flush = 1;
+ struct vxlan_sock *vs = container_of(uoff, struct vxlan_sock,
+ udp_offloads);
+ u32 flags;
off_vx = skb_gro_offset(skb);
hlen = off_vx + sizeof(*vh);
@@ -557,6 +600,19 @@
goto out;
}
+ skb_gro_pull(skb, sizeof(struct vxlanhdr)); /* pull vxlan header */
+ skb_gro_postpull_rcsum(skb, vh, sizeof(struct vxlanhdr));
+
+ flags = ntohl(vh->vx_flags);
+
+ if ((flags & VXLAN_HF_RCO) && (vs->flags & VXLAN_F_REMCSUM_RX)) {
+ vh = vxlan_gro_remcsum(skb, off_vx, vh, sizeof(struct vxlanhdr),
+ ntohl(vh->vx_vni));
+
+ if (!vh)
+ goto out;
+ }
+
flush = 0;
for (p = *head; p; p = p->next) {
@@ -570,8 +626,6 @@
}
}
- skb_gro_pull(skb, sizeof(struct vxlanhdr));
- skb_gro_postpull_rcsum(skb, vh, sizeof(struct vxlanhdr));
pp = eth_gro_receive(head, skb);
out:
@@ -1087,6 +1141,42 @@
dev_put(vxlan->dev);
}
+static struct vxlanhdr *vxlan_remcsum(struct sk_buff *skb, struct vxlanhdr *vh,
+ size_t hdrlen, u32 data)
+{
+ size_t start, offset, plen;
+ __wsum delta;
+
+ if (skb->remcsum_offload) {
+ /* Already processed in GRO path */
+ skb->remcsum_offload = 0;
+ return vh;
+ }
+
+ start = (data & VXLAN_RCO_MASK) << VXLAN_RCO_SHIFT;
+ offset = start + ((data & VXLAN_RCO_UDP) ?
+ offsetof(struct udphdr, check) :
+ offsetof(struct tcphdr, check));
+
+ plen = hdrlen + offset + sizeof(u16);
+
+ if (!pskb_may_pull(skb, plen))
+ return NULL;
+
+ vh = (struct vxlanhdr *)(udp_hdr(skb) + 1);
+
+ if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE))
+ __skb_checksum_complete(skb);
+
+ delta = remcsum_adjust((void *)vh + hdrlen,
+ skb->csum, start, offset);
+
+ /* Adjust skb->csum since we changed the packet */
+ skb->csum = csum_add(skb->csum, delta);
+
+ return vh;
+}
+
/* Callback from net/ipv4/udp.c to receive packets */
static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
{
@@ -1111,12 +1201,22 @@
if (iptunnel_pull_header(skb, VXLAN_HLEN, htons(ETH_P_TEB)))
goto drop;
+ vxh = (struct vxlanhdr *)(udp_hdr(skb) + 1);
vs = rcu_dereference_sk_user_data(sk);
if (!vs)
goto drop;
- if (flags || (vni & 0xff)) {
+ if ((flags & VXLAN_HF_RCO) && (vs->flags & VXLAN_F_REMCSUM_RX)) {
+ vxh = vxlan_remcsum(skb, vxh, sizeof(struct vxlanhdr), vni);
+ if (!vxh)
+ goto drop;
+
+ flags &= ~VXLAN_HF_RCO;
+ vni &= VXLAN_VID_MASK;
+ }
+
+ if (flags || (vni & ~VXLAN_VID_MASK)) {
/* If there are any unprocessed flags remaining treat
* this as a malformed packet. This behavior diverges from
* VXLAN RFC (RFC7348) which stipulates that bits in reserved
@@ -1553,8 +1653,23 @@
int min_headroom;
int err;
bool udp_sum = !udp_get_no_check6_tx(vs->sock->sk);
+ int type = udp_sum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
+ u16 hdrlen = sizeof(struct vxlanhdr);
- skb = udp_tunnel_handle_offloads(skb, udp_sum);
+ if ((vs->flags & VXLAN_F_REMCSUM_TX) &&
+ skb->ip_summed == CHECKSUM_PARTIAL) {
+ int csum_start = skb_checksum_start_offset(skb);
+
+ if (csum_start <= VXLAN_MAX_REMCSUM_START &&
+ !(csum_start & VXLAN_RCO_SHIFT_MASK) &&
+ (skb->csum_offset == offsetof(struct udphdr, check) ||
+ skb->csum_offset == offsetof(struct tcphdr, check))) {
+ udp_sum = false;
+ type |= SKB_GSO_TUNNEL_REMCSUM;
+ }
+ }
+
+ skb = iptunnel_handle_offloads(skb, udp_sum, type);
if (IS_ERR(skb)) {
err = -EINVAL;
goto err;
@@ -1583,6 +1698,22 @@
vxh->vx_flags = htonl(VXLAN_HF_VNI);
vxh->vx_vni = vni;
+ if (type & SKB_GSO_TUNNEL_REMCSUM) {
+ u32 data = (skb_checksum_start_offset(skb) - hdrlen) >>
+ VXLAN_RCO_SHIFT;
+
+ if (skb->csum_offset == offsetof(struct udphdr, check))
+ data |= VXLAN_RCO_UDP;
+
+ vxh->vx_vni |= htonl(data);
+ vxh->vx_flags |= htonl(VXLAN_HF_RCO);
+
+ if (!skb_is_gso(skb)) {
+ skb->ip_summed = CHECKSUM_NONE;
+ skb->encapsulation = 0;
+ }
+ }
+
skb_set_inner_protocol(skb, htons(ETH_P_TEB));
udp_tunnel6_xmit_skb(vs->sock, dst, skb, dev, saddr, daddr, prio,
@@ -1603,8 +1734,23 @@
int min_headroom;
int err;
bool udp_sum = !vs->sock->sk->sk_no_check_tx;
+ int type = udp_sum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
+ u16 hdrlen = sizeof(struct vxlanhdr);
- skb = udp_tunnel_handle_offloads(skb, udp_sum);
+ if ((vs->flags & VXLAN_F_REMCSUM_TX) &&
+ skb->ip_summed == CHECKSUM_PARTIAL) {
+ int csum_start = skb_checksum_start_offset(skb);
+
+ if (csum_start <= VXLAN_MAX_REMCSUM_START &&
+ !(csum_start & VXLAN_RCO_SHIFT_MASK) &&
+ (skb->csum_offset == offsetof(struct udphdr, check) ||
+ skb->csum_offset == offsetof(struct tcphdr, check))) {
+ udp_sum = false;
+ type |= SKB_GSO_TUNNEL_REMCSUM;
+ }
+ }
+
+ skb = iptunnel_handle_offloads(skb, udp_sum, type);
if (IS_ERR(skb))
return PTR_ERR(skb);
@@ -1627,6 +1773,22 @@
vxh->vx_flags = htonl(VXLAN_HF_VNI);
vxh->vx_vni = vni;
+ if (type & SKB_GSO_TUNNEL_REMCSUM) {
+ u32 data = (skb_checksum_start_offset(skb) - hdrlen) >>
+ VXLAN_RCO_SHIFT;
+
+ if (skb->csum_offset == offsetof(struct udphdr, check))
+ data |= VXLAN_RCO_UDP;
+
+ vxh->vx_vni |= htonl(data);
+ vxh->vx_flags |= htonl(VXLAN_HF_RCO);
+
+ if (!skb_is_gso(skb)) {
+ skb->ip_summed = CHECKSUM_NONE;
+ skb->encapsulation = 0;
+ }
+ }
+
skb_set_inner_protocol(skb, htons(ETH_P_TEB));
return udp_tunnel_xmit_skb(vs->sock, rt, skb, src, dst, tos,
@@ -2218,6 +2380,8 @@
[IFLA_VXLAN_UDP_CSUM] = { .type = NLA_U8 },
[IFLA_VXLAN_UDP_ZERO_CSUM6_TX] = { .type = NLA_U8 },
[IFLA_VXLAN_UDP_ZERO_CSUM6_RX] = { .type = NLA_U8 },
+ [IFLA_VXLAN_REMCSUM_TX] = { .type = NLA_U8 },
+ [IFLA_VXLAN_REMCSUM_RX] = { .type = NLA_U8 },
};
static int vxlan_validate(struct nlattr *tb[], struct nlattr *data[])
@@ -2339,6 +2503,7 @@
atomic_set(&vs->refcnt, 1);
vs->rcv = rcv;
vs->data = data;
+ vs->flags = flags;
/* Initialize the vxlan udp offloads structure */
vs->udp_offloads.port = port;
@@ -2533,6 +2698,14 @@
nla_get_u8(data[IFLA_VXLAN_UDP_ZERO_CSUM6_RX]))
vxlan->flags |= VXLAN_F_UDP_ZERO_CSUM6_RX;
+ if (data[IFLA_VXLAN_REMCSUM_TX] &&
+ nla_get_u8(data[IFLA_VXLAN_REMCSUM_TX]))
+ vxlan->flags |= VXLAN_F_REMCSUM_TX;
+
+ if (data[IFLA_VXLAN_REMCSUM_RX] &&
+ nla_get_u8(data[IFLA_VXLAN_REMCSUM_RX]))
+ vxlan->flags |= VXLAN_F_REMCSUM_RX;
+
if (vxlan_find_vni(net, vni, use_ipv6 ? AF_INET6 : AF_INET,
vxlan->dst_port)) {
pr_info("duplicate VNI %u\n", vni);
@@ -2601,6 +2774,8 @@
nla_total_size(sizeof(__u8)) + /* IFLA_VXLAN_UDP_CSUM */
nla_total_size(sizeof(__u8)) + /* IFLA_VXLAN_UDP_ZERO_CSUM6_TX */
nla_total_size(sizeof(__u8)) + /* IFLA_VXLAN_UDP_ZERO_CSUM6_RX */
+ nla_total_size(sizeof(__u8)) + /* IFLA_VXLAN_REMCSUM_TX */
+ nla_total_size(sizeof(__u8)) + /* IFLA_VXLAN_REMCSUM_RX */
0;
}
@@ -2666,7 +2841,11 @@
nla_put_u8(skb, IFLA_VXLAN_UDP_ZERO_CSUM6_TX,
!!(vxlan->flags & VXLAN_F_UDP_ZERO_CSUM6_TX)) ||
nla_put_u8(skb, IFLA_VXLAN_UDP_ZERO_CSUM6_RX,
- !!(vxlan->flags & VXLAN_F_UDP_ZERO_CSUM6_RX)))
+ !!(vxlan->flags & VXLAN_F_UDP_ZERO_CSUM6_RX)) ||
+ nla_put_u8(skb, IFLA_VXLAN_REMCSUM_TX,
+ !!(vxlan->flags & VXLAN_F_REMCSUM_TX)) ||
+ nla_put_u8(skb, IFLA_VXLAN_REMCSUM_RX,
+ !!(vxlan->flags & VXLAN_F_REMCSUM_RX)))
goto nla_put_failure;
if (nla_put(skb, IFLA_VXLAN_PORT_RANGE, sizeof(ports), &ports))