[Qemu-devel] [ RFC Patch v6 2/3] virtio-net rsc: support coalescing ipv6 tcp traffic

[wexu@redhat.com]

From: Wei Xu <wexu@redhat.com>

Most stuffs are like ipv4 2 differences between ipv4 and ipv6.

1. Fragment length in ipv4 header includes itself, while it's not
included for ipv6, thus means ipv6 can carry a real '65535' payload.

2. IPv6 header does not need calculate header checksum.

Signed-off-by: Wei Xu <wexu@redhat.com>
---
 hw/net/virtio-net.c | 152 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 144 insertions(+), 8 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index b3bb63b..cc8cbe4 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -53,6 +53,10 @@
 /* header length value in ip header without option */
 #define VIRTIO_NET_IP4_HEADER_LENGTH 5
 
+#define ETH_IP6_HDR_SZ (ETH_HDR_SZ + IP6_HDR_SZ)
+#define VIRTIO_NET_IP6_ADDR_SIZE   32      /* ipv6 saddr + daddr */
+#define VIRTIO_NET_MAX_IP6_PAYLOAD VIRTIO_NET_MAX_TCP_PAYLOAD
+
 /* Purge coalesced packets timer interval, This value affects the performance
    a lot, and should be tuned carefully, '300000'(300us) is the recommended
    value to pass the WHQL test, '50000' can gain 2x netperf throughput with
@@ -1724,6 +1728,25 @@ static void virtio_net_rsc_extract_unit4(NetRscChain *chain,
     unit->payload = htons(*unit->ip_plen) - ip_hdrlen - unit->tcp_hdrlen;
 }
 
+static void virtio_net_rsc_extract_unit6(NetRscChain *chain,
+                                         const uint8_t *buf, NetRscUnit* unit)
+{
+    uint16_t hdr_len;
+    struct ip6_header *ip6;
+
+    hdr_len = ((VirtIONet *)(chain->n))->guest_hdr_len;
+    ip6 = (struct ip6_header *)(buf + hdr_len + sizeof(struct eth_header));
+    unit->ip = ip6;
+    unit->ip_plen = &(ip6->ip6_ctlun.ip6_un1.ip6_un1_plen);
+    unit->tcp = (struct tcp_header *)(((uint8_t *)unit->ip)\
+                                        + sizeof(struct ip6_header));
+    unit->tcp_hdrlen = (htons(unit->tcp->th_offset_flags) & 0xF000) >> 10;
+
+    /* There is a difference between payload lenght in ipv4 and v6,
+       ip header is excluded in ipv6 */
+    unit->payload = htons(*unit->ip_plen) - unit->tcp_hdrlen;
+}
+
 static void virtio_net_rsc_ipv4_checksum(struct virtio_net_hdr *vhdr,
                                          struct ip_header *ip)
 {
@@ -1742,7 +1765,9 @@ static size_t virtio_net_rsc_drain_seg(NetRscChain *chain, NetRscSeg *seg)
     struct virtio_net_hdr *h;
 
     h = (struct virtio_net_hdr *)seg->buf;
-    virtio_net_rsc_ipv4_checksum(h, seg->unit.ip);
+    if ((chain->proto == ETH_P_IP) && seg->is_coalesced) {
+        virtio_net_rsc_ipv4_checksum(h, seg->unit.ip);
+    }
     ret = virtio_net_do_receive(seg->nc, seg->buf, seg->size);
     QTAILQ_REMOVE(&chain->buffers, seg, next);
     g_free(seg->buf);
@@ -1798,7 +1823,7 @@ static void virtio_net_rsc_cache_buf(NetRscChain *chain, NetClientState *nc,
     hdr_len = chain->n->guest_hdr_len;
     seg = g_malloc(sizeof(NetRscSeg));
     seg->buf = g_malloc(hdr_len + sizeof(struct eth_header)\
-                   + VIRTIO_NET_MAX_TCP_PAYLOAD);
+                   + sizeof(struct ip6_header) + VIRTIO_NET_MAX_TCP_PAYLOAD);
     memcpy(seg->buf, buf, size);
     seg->size = size;
     seg->packets = 1;
@@ -1809,7 +1834,18 @@ static void virtio_net_rsc_cache_buf(NetRscChain *chain, NetClientState *nc,
     QTAILQ_INSERT_TAIL(&chain->buffers, seg, next);
     chain->stat.cache++;
 
-    virtio_net_rsc_extract_unit4(chain, seg->buf, &seg->unit);
+    switch (chain->proto) {
+    case ETH_P_IP:
+        virtio_net_rsc_extract_unit4(chain, seg->buf, &seg->unit);
+        break;
+
+    case ETH_P_IPV6:
+        virtio_net_rsc_extract_unit6(chain, seg->buf, &seg->unit);
+        break;
+
+    default:
+        g_assert_not_reached();
+    }
 }
 
 static int32_t virtio_net_rsc_handle_ack(NetRscChain *chain,
@@ -1929,6 +1965,24 @@ static int32_t virtio_net_rsc_coalesce4(NetRscChain *chain, NetRscSeg *seg,
     return virtio_net_rsc_coalesce_data(chain, seg, buf, unit);
 }
 
+static int32_t virtio_net_rsc_coalesce6(NetRscChain *chain, NetRscSeg *seg,
+                        const uint8_t *buf, size_t size, NetRscUnit *unit)
+{
+    struct ip6_header *ip1, *ip2;
+
+    ip1 = (struct ip6_header *)(unit->ip);
+    ip2 = (struct ip6_header *)(seg->unit.ip);
+    if (memcmp(&ip1->ip6_src, &ip2->ip6_src, sizeof(struct in6_address))
+        || memcmp(&ip1->ip6_dst, &ip2->ip6_dst, sizeof(struct in6_address))
+        || (unit->tcp->th_sport ^ seg->unit.tcp->th_sport)
+        || (unit->tcp->th_dport ^ seg->unit.tcp->th_dport)) {
+            chain->stat.no_match++;
+            return RSC_NO_MATCH;
+    }
+
+    return virtio_net_rsc_coalesce_data(chain, seg, buf, unit);
+}
+
 /* Pakcets with 'SYN' should bypass, other flag should be sent after drain
  * to prevent out of order */
 static int virtio_net_rsc_tcp_ctrl_check(NetRscChain *chain,
@@ -1981,7 +2035,11 @@ static size_t virtio_net_rsc_do_coalesce(NetRscChain *chain, NetClientState *nc,
     NetRscSeg *seg, *nseg;
 
     QTAILQ_FOREACH_SAFE(seg, &chain->buffers, next, nseg) {
-        ret = virtio_net_rsc_coalesce4(chain, seg, buf, size, unit);
+        if (chain->proto == ETH_P_IP) {
+            ret = virtio_net_rsc_coalesce4(chain, seg, buf, size, unit);
+        } else {
+            ret = virtio_net_rsc_coalesce6(chain, seg, buf, size, unit);
+        }
 
         if (ret == RSC_FINAL) {
             if (virtio_net_rsc_drain_seg(chain, seg) == 0) {
@@ -2106,13 +2164,82 @@ static size_t virtio_net_rsc_receive4(NetRscChain *chain, NetClientState* nc,
     return virtio_net_rsc_do_coalesce(chain, nc, buf, size, &unit);
 }
 
+static int32_t virtio_net_rsc_sanity_check6(NetRscChain *chain,
+                                            struct ip6_header *ip6,
+                                            const uint8_t *buf, size_t size)
+{
+    uint16_t ip_len;
+    uint16_t hdr_len;
+
+    hdr_len = ((VirtIONet *)(chain->n))->guest_hdr_len;
+    if (size < (hdr_len + sizeof(struct eth_header) + sizeof(struct ip6_header)
+        + sizeof(tcp_header))) {
+        return RSC_BYPASS;
+    }
+
+    if (((ip6->ip6_ctlun.ip6_un1.ip6_un1_flow & 0xF0) >> 4)
+        != IP_HEADER_VERSION_6) {
+        return RSC_BYPASS;
+    }
+
+    /* Both option and protocol is checked in this */
+    if (ip6->ip6_ctlun.ip6_un1.ip6_un1_nxt != IPPROTO_TCP) {
+        chain->stat.bypass_not_tcp++;
+        return RSC_BYPASS;
+    }
+
+    ip_len = htons(ip6->ip6_ctlun.ip6_un1.ip6_un1_plen);
+    if (ip_len < sizeof(struct tcp_header)
+        || ip_len > (size - hdr_len - sizeof(struct eth_header)
+                     - sizeof(struct ip6_header))) {
+        chain->stat.ip_hacked++;
+        return RSC_BYPASS;
+    }
+
+    return RSC_WANT;
+}
+
+static size_t virtio_net_rsc_receive6(void *opq, NetClientState* nc,
+                                      const uint8_t *buf, size_t size)
+{
+    int32_t ret;
+    uint16_t hdr_len;
+    NetRscChain *chain;
+    NetRscUnit unit;
+
+    chain = (NetRscChain *)opq;
+    hdr_len = ((VirtIONet *)(chain->n))->guest_hdr_len;
+    virtio_net_rsc_extract_unit6(chain, buf, &unit);
+    if (RSC_WANT != virtio_net_rsc_sanity_check6(chain,
+                                                 unit.ip, buf, size)) {
+        return virtio_net_do_receive(nc, buf, size);
+    }
+
+    ret = virtio_net_rsc_tcp_ctrl_check(chain, unit.tcp);
+    if (ret == RSC_BYPASS) {
+        return virtio_net_do_receive(nc, buf, size);
+    } else if (ret == RSC_FINAL) {
+        return virtio_net_rsc_drain_flow(chain, nc, buf, size,
+                ((hdr_len + sizeof(struct eth_header)) + 8),
+                VIRTIO_NET_IP6_ADDR_SIZE,
+                hdr_len + sizeof(struct eth_header) + sizeof(struct ip6_header),
+                VIRTIO_NET_TCP_PORT_SIZE);
+    }
+
+    if (virtio_net_rsc_empty_cache(chain, nc, buf, size)) {
+        return size;
+    }
+
+    return virtio_net_rsc_do_coalesce(chain, nc, buf, size, &unit);
+}
+
 static NetRscChain *virtio_net_rsc_lookup_chain(VirtIONet * n,
                                                 NetClientState *nc,
                                                 uint16_t proto)
 {
     NetRscChain *chain;
 
-    if (proto != (uint16_t)ETH_P_IP) {
+    if ((proto != (uint16_t)ETH_P_IP) && (proto != (uint16_t)ETH_P_IPV6)) {
         return NULL;
     }
 
@@ -2125,8 +2252,13 @@ static NetRscChain *virtio_net_rsc_lookup_chain(VirtIONet * n,
     chain = g_malloc(sizeof(*chain));
     chain->n = n;
     chain->proto = proto;
-    chain->max_payload = VIRTIO_NET_MAX_IP4_PAYLOAD;
-    chain->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
+    if (proto == (uint16_t)ETH_P_IP) {
+        chain->max_payload = VIRTIO_NET_MAX_IP4_PAYLOAD;
+        chain->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
+    } else {
+        chain->max_payload = VIRTIO_NET_MAX_IP6_PAYLOAD;
+        chain->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
+    }
     chain->drain_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
                                       virtio_net_rsc_purge, chain);
     memset(&chain->stat, 0, sizeof(chain->stat));
@@ -2158,7 +2290,11 @@ static ssize_t virtio_net_rsc_receive(NetClientState *nc,
         return virtio_net_do_receive(nc, buf, size);
     } else {
         chain->stat.received++;
-        return virtio_net_rsc_receive4(chain, nc, buf, size);
+        if (proto == (uint16_t)ETH_P_IP) {
+            return virtio_net_rsc_receive4(chain, nc, buf, size);
+        } else  {
+            return virtio_net_rsc_receive6(chain, nc, buf, size);
+        }
     }
 }
 
-- 
2.7.1