Implement TCP Segmentation Offload for vio(4)

Tested by Brian Conway and bluhm
With tweaks from bluhm

ok bluhm

diff --git a/sys/dev/pv/if_vio.c b/sys/dev/pv/if_vio.c
index db399e7..9ad8e36 100644 (file)
--- a/sys/dev/pv/if_vio.c
+++ b/sys/dev/pv/if_vio.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: if_vio.c,v 1.31 2024/02/14 22:41:48 bluhm Exp $       */
+/*     $OpenBSD: if_vio.c,v 1.32 2024/04/10 19:55:50 jan Exp $ */
 
 /*
  * Copyright (c) 2012 Stefan Fritsch, Alexander Fiveg.
@@ -43,12 +43,12 @@
 
 #include <net/if.h>
 #include <net/if_media.h>
+#include <net/route.h>
 
-#include <netinet/in.h>
 #include <netinet/if_ether.h>
-#include <netinet/ip.h>
-#include <netinet/ip6.h>
 #include <netinet/tcp.h>
+#include <netinet/tcp_timer.h>
+#include <netinet/tcp_var.h>
 #include <netinet/udp.h>
 
 #if NBPFILTER > 0
@@ -537,6 +537,9 @@ vio_attach(struct device *parent, struct device *self, void *aux)
            VIRTIO_NET_F_MRG_RXBUF | VIRTIO_NET_F_CSUM |
            VIRTIO_F_RING_EVENT_IDX | VIRTIO_NET_F_GUEST_CSUM;
 
+       vsc->sc_driver_features |= VIRTIO_NET_F_HOST_TSO4;
+       vsc->sc_driver_features |= VIRTIO_NET_F_HOST_TSO6;
+
        virtio_negotiate_features(vsc, virtio_net_feature_names);
        if (virtio_has_feature(vsc, VIRTIO_NET_F_MAC)) {
                vio_get_lladdr(&sc->sc_ac, vsc);
@@ -553,9 +556,9 @@ vio_attach(struct device *parent, struct device *self, void *aux)
                sc->sc_hdr_size = offsetof(struct virtio_net_hdr, num_buffers);
        }
        if (virtio_has_feature(vsc, VIRTIO_NET_F_MRG_RXBUF))
-               ifp->if_hardmtu = 16000; /* arbitrary limit */
+               ifp->if_hardmtu = MAXMCLBYTES;
        else
-               ifp->if_hardmtu = MCLBYTES - sc->sc_hdr_size - ETHER_HDR_LEN;
+               ifp->if_hardmtu = MAXMCLBYTES - sc->sc_hdr_size - ETHER_HDR_LEN;
 
        if (virtio_alloc_vq(vsc, &sc->sc_vq[VQRX], 0, MCLBYTES, 2, "rx") != 0)
                goto err;
@@ -595,6 +598,10 @@ vio_attach(struct device *parent, struct device *self, void *aux)
        if (virtio_has_feature(vsc, VIRTIO_NET_F_CSUM))
                ifp->if_capabilities |= IFCAP_CSUM_TCPv4|IFCAP_CSUM_UDPv4|
                    IFCAP_CSUM_TCPv6|IFCAP_CSUM_UDPv6;
+       if (virtio_has_feature(vsc, VIRTIO_NET_F_HOST_TSO4))
+               ifp->if_capabilities |= IFCAP_TSOv4;
+       if (virtio_has_feature(vsc, VIRTIO_NET_F_HOST_TSO6))
+               ifp->if_capabilities |= IFCAP_TSOv6;
        ifq_init_maxlen(&ifp->if_snd, vsc->sc_vqs[1].vq_num - 1);
        ifmedia_init(&sc->sc_media, 0, vio_media_change, vio_media_status);
        ifmedia_add(&sc->sc_media, IFM_ETHER | IFM_AUTO, 0, NULL);
@@ -714,6 +721,85 @@ vio_stop(struct ifnet *ifp, int disable)
        }
 }
 
+static inline uint16_t
+vio_cksum_update(uint32_t cksum, uint16_t paylen)
+{
+       /* Add payload length */
+       cksum += paylen;
+
+       /* Fold back to 16 bit */
+       cksum += cksum >> 16;
+
+       return (uint16_t)(cksum);
+}
+
+void
+vio_tx_offload(struct virtio_net_hdr *hdr, struct mbuf *m)
+{
+       struct ether_extracted ext;
+
+       /*
+        * Checksum Offload
+        */
+
+       if (!ISSET(m->m_pkthdr.csum_flags, M_TCP_CSUM_OUT) &&
+           !ISSET(m->m_pkthdr.csum_flags, M_UDP_CSUM_OUT))
+               return;
+
+       ether_extract_headers(m, &ext);
+
+       /* Consistency Checks */
+       if ((!ext.ip4 && !ext.ip6) || (!ext.tcp && !ext.udp))
+               return;
+
+       if ((ext.tcp && !ISSET(m->m_pkthdr.csum_flags, M_TCP_CSUM_OUT)) ||
+           (ext.udp && !ISSET(m->m_pkthdr.csum_flags, M_UDP_CSUM_OUT)))
+               return;
+
+       hdr->csum_start = sizeof(*ext.eh);
+#if NVLAN > 0
+       if (ext.evh)
+               hdr->csum_start = sizeof(*ext.evh);
+#endif
+       hdr->csum_start += ext.iphlen;
+
+       if (ext.tcp)
+               hdr->csum_offset = offsetof(struct tcphdr, th_sum);
+       else if (ext.udp)
+               hdr->csum_offset = offsetof(struct udphdr, uh_sum);
+
+       hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+
+       /*
+        * TCP Segmentation Offload
+        */
+
+       if (!ISSET(m->m_pkthdr.csum_flags, M_TCP_TSO))
+               return;
+
+       if (!ext.tcp) {
+               tcpstat_inc(tcps_outbadtso);
+               return;
+       }
+
+       hdr->hdr_len = hdr->csum_start + ext.tcphlen;
+       hdr->gso_size = m->m_pkthdr.ph_mss;
+
+       if (ext.ip4)
+               hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
+#ifdef INET6
+       else if (ext.ip6)
+               hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
+#endif
+
+       /* VirtIO-Net need pseudo header cksum with IP-payload length for TSO */
+       ext.tcp->th_sum = vio_cksum_update(ext.tcp->th_sum,
+           htons(ext.iplen - ext.iphlen));
+
+       tcpstat_add(tcps_outpkttso,
+           (ext.paylen + m->m_pkthdr.ph_mss - 1) / m->m_pkthdr.ph_mss);
+}
+
 void
 vio_start(struct ifnet *ifp)
 {
@@ -750,24 +836,7 @@ again:
 
                hdr = &sc->sc_tx_hdrs[slot];
                memset(hdr, 0, sc->sc_hdr_size);
-               if (m->m_pkthdr.csum_flags & (M_TCP_CSUM_OUT|M_UDP_CSUM_OUT)) {
-                       struct ether_extracted ext;
-
-                       ether_extract_headers(m, &ext);
-                       hdr->csum_start = sizeof(*ext.eh);
-#if NVLAN > 0
-                       if (ext.evh)
-                               hdr->csum_start = sizeof(*ext.evh);
-#endif
-                       if (m->m_pkthdr.csum_flags & M_TCP_CSUM_OUT)
-                               hdr->csum_offset = offsetof(struct tcphdr, th_sum);
-                       else
-                               hdr->csum_offset = offsetof(struct udphdr, uh_sum);
-
-                       if (ext.ip4 || ext.ip6)
-                               hdr->csum_start += ext.iphlen;
-                       hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-               }
+               vio_tx_offload(hdr, m);
 
                r = vio_encap(sc, slot, m);
                if (r != 0) {