rework checksum/vlan offloading, and enable it for ipv6 too.

this is based on work by jan@ and bluhm@. the most interesting
change on top of their work is to move the parsing of the IP packets
to figure out ip and udp/tcp offsets before a possible call to
m_defrag.

if an l4 offload is requested, it's only requested by the stack
when the payload is correctly aligned and with each header contiguous
in memory. this means you can use m_getptr and cast the packet data
to the relevant headers to read them directly because that's what
the stack does when it's working on them. this makes it cheap to
work on them too.

however, if you m_defrag, it ignores the alignment and ends up
making it unsafe to dereference the ip and tcp/udp payloads on
strict alignment architectures. if we want to look at the headers
after m_defrag, we'd likely have to copy them onto the stack first.

we got away with this before because we were lucky with the code
that's generated on strict alignment archs for looking at the ip
hl and proto fields. that luck might run out though.

while here i've also tweaked the vlan handling code, and generally
tried to make it more readable.

ok bluhm@ jmatthew@

1 files changed, 87 insertions, 122 deletions

diff --git a/sys/dev/pci/if_ix.c b/sys/dev/pci/if_ix.c
index a5d1f60e43e..2fda53fdb61 100644
--- a/sys/dev/pci/if_ix.c
+++ b/sys/dev/pci/if_ix.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_ix.c,v 1.181 2022/01/27 18:28:44 bluhm Exp $	*/
+/*	$OpenBSD: if_ix.c,v 1.182 2022/02/08 03:38:00 dlg Exp $	*/
 
 /******************************************************************************
 
@@ -156,7 +156,8 @@ int	ixgbe_encap(struct tx_ring *, struct mbuf *);
 int	ixgbe_dma_malloc(struct ix_softc *, bus_size_t,
 		    struct ixgbe_dma_alloc *, int);
 void	ixgbe_dma_free(struct ix_softc *, struct ixgbe_dma_alloc *);
-int	ixgbe_tx_ctx_setup(struct tx_ring *, struct mbuf *, uint32_t *,
+static int
+	ixgbe_tx_ctx_setup(struct tx_ring *, struct mbuf *, uint32_t *,
 	    uint32_t *);
 int	ixgbe_tso_setup(struct tx_ring *, struct mbuf *, uint32_t *,
 	    uint32_t *);
@@ -1391,11 +1392,6 @@ ixgbe_encap(struct tx_ring *txr, struct mbuf *m_head)
 	cmd_type_len = (IXGBE_ADVTXD_DTYP_DATA |
 	    IXGBE_ADVTXD_DCMD_IFCS | IXGBE_ADVTXD_DCMD_DEXT);
 
-#if NVLAN > 0
-	if (m_head->m_flags & M_VLANTAG)
-		cmd_type_len |= IXGBE_ADVTXD_DCMD_VLE;
-#endif
-
 	/*
 	 * Important to capture the first descriptor
 	 * used because it will contain the index of
@@ -1406,6 +1402,14 @@ ixgbe_encap(struct tx_ring *txr, struct mbuf *m_head)
 	map = txbuf->map;
 
 	/*
+	 * Set the appropriate offload context
+	 * this will becomes the first descriptor.
+	 */
+	ntxc = ixgbe_tx_ctx_setup(txr, m_head, &cmd_type_len, &olinfo_status);
+	if (ntxc == -1)
+		goto xmit_fail;
+
+	/*
 	 * Map the packet for DMA.
 	 */
 	switch (bus_dmamap_load_mbuf(txr->txdma.dma_tag, map,
@@ -1422,14 +1426,6 @@ ixgbe_encap(struct tx_ring *txr, struct mbuf *m_head)
 		return (0);
 	}
 
-	/*
-	 * Set the appropriate offload context
-	 * this will becomes the first descriptor.
-	 */
-	ntxc = ixgbe_tx_ctx_setup(txr, m_head, &cmd_type_len, &olinfo_status);
-	if (ntxc == -1)
-		goto xmit_fail;
-
 	i = txr->next_avail_desc + ntxc;
 	if (i >= sc->num_tx_desc)
 		i -= sc->num_tx_desc;
@@ -1880,6 +1876,7 @@ ixgbe_setup_interface(struct ix_softc *sc)
 #endif
 
 	ifp->if_capabilities |= IFCAP_CSUM_TCPv4 | IFCAP_CSUM_UDPv4;
+	ifp->if_capabilities |= IFCAP_CSUM_TCPv6 | IFCAP_CSUM_UDPv6;
 
 	/*
 	 * Specify the media types supported by this sc and register
@@ -2426,138 +2423,106 @@ ixgbe_free_transmit_buffers(struct tx_ring *txr)
  *
  **********************************************************************/
 
-int
-ixgbe_tx_ctx_setup(struct tx_ring *txr, struct mbuf *mp,
-    uint32_t *cmd_type_len, uint32_t *olinfo_status)
+static inline void
+ixgbe_csum_offload(struct mbuf *mp,
+    uint32_t *vlan_macip_lens, uint32_t *type_tucmd_mlhl)
 {
-	struct ixgbe_adv_tx_context_desc *TXD;
-	struct ixgbe_tx_buf *tx_buffer;
-#if NVLAN > 0
-	struct ether_vlan_header *eh;
-#else
-	struct ether_header *eh;
-#endif
-	struct ip *ip;
-#ifdef notyet
-	struct ip6_hdr *ip6;
-#endif
+	struct ether_header *eh = mtod(mp, struct ether_header *);
 	struct mbuf *m;
-	int	ipoff;
-	uint32_t vlan_macip_lens = 0, type_tucmd_mlhl = 0;
-	int 	ehdrlen, ip_hlen = 0;
-	uint16_t etype;
-	uint8_t	ipproto = 0;
-	int	offload = TRUE;
-	int	ctxd = txr->next_avail_desc;
-#if NVLAN > 0
-	uint16_t vtag = 0;
-#endif
+	int hoff;
+	uint32_t iphlen;
+	uint8_t ipproto;
 
-#if notyet
-	/* First check if TSO is to be used */
-	if (mp->m_pkthdr.csum_flags & CSUM_TSO)
-		return (ixgbe_tso_setup(txr, mp, cmd_type_len, olinfo_status));
-#endif
+	*vlan_macip_lens |= (sizeof(*eh) << IXGBE_ADVTXD_MACLEN_SHIFT);
 
-	if ((mp->m_pkthdr.csum_flags & (M_TCP_CSUM_OUT | M_UDP_CSUM_OUT)) == 0)
-		offload = FALSE;
+	switch (ntohs(eh->ether_type)) {
+	case ETHERTYPE_IP: {
+		struct ip *ip;
 
-	/* Indicate the whole packet as payload when not doing TSO */
-	*olinfo_status |= mp->m_pkthdr.len << IXGBE_ADVTXD_PAYLEN_SHIFT;
+		m = m_getptr(mp, sizeof(*eh), &hoff);
+		KASSERT(m != NULL && m->m_len - hoff >= sizeof(*ip));
+		ip = (struct ip *)(mtod(m, caddr_t) + hoff);
 
-	/* Now ready a context descriptor */
-	TXD = (struct ixgbe_adv_tx_context_desc *) &txr->tx_base[ctxd];
-	tx_buffer = &txr->tx_buffers[ctxd];
-
-	/*
-	 * In advanced descriptors the vlan tag must
-	 * be placed into the descriptor itself. Hence
-	 * we need to make one even if not doing offloads.
-	 */
-#if NVLAN > 0
-	if (mp->m_flags & M_VLANTAG) {
-		vtag = mp->m_pkthdr.ether_vtag;
-		vlan_macip_lens |= (vtag << IXGBE_ADVTXD_VLAN_SHIFT);
-	} else
-#endif
-	if (offload == FALSE)
-		return (0);	/* No need for CTX */
+		iphlen = ip->ip_hl << 2;
+		ipproto = ip->ip_p;
 
-	/*
-	 * Determine where frame payload starts.
-	 * Jump over vlan headers if already present,
-	 * helpful for QinQ too.
-	 */
-	if (mp->m_len < sizeof(struct ether_header))
-		return (-1);
-#if NVLAN > 0
-	eh = mtod(mp, struct ether_vlan_header *);
-	if (eh->evl_encap_proto == htons(ETHERTYPE_VLAN)) {
-		if (mp->m_len < sizeof(struct ether_vlan_header))
-			return (-1);
-		etype = ntohs(eh->evl_proto);
-		ehdrlen = ETHER_HDR_LEN + ETHER_VLAN_ENCAP_LEN;
-	} else {
-		etype = ntohs(eh->evl_encap_proto);
-		ehdrlen = ETHER_HDR_LEN;
+		*type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_IPV4;
+		break;
 	}
-#else
-	eh = mtod(mp, struct ether_header *);
-	etype = ntohs(eh->ether_type);
-	ehdrlen = ETHER_HDR_LEN;
-#endif
 
-	/* Set the ether header length */
-	vlan_macip_lens |= ehdrlen << IXGBE_ADVTXD_MACLEN_SHIFT;
-
-	switch (etype) {
-	case ETHERTYPE_IP:
-		if (mp->m_pkthdr.len < ehdrlen + sizeof(*ip))
-			return (-1);
-		m = m_getptr(mp, ehdrlen, &ipoff);
-		KASSERT(m != NULL && m->m_len - ipoff >= sizeof(*ip));
-		ip = (struct ip *)(m->m_data + ipoff);
-		ip_hlen = ip->ip_hl << 2;
-		ipproto = ip->ip_p;
-		type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_IPV4;
-		break;
-#ifdef notyet
-	case ETHERTYPE_IPV6:
-		if (mp->m_pkthdr.len < ehdrlen + sizeof(*ip6))
-			return (-1);
-		m = m_getptr(mp, ehdrlen, &ipoff);
-		KASSERT(m != NULL && m->m_len - ipoff >= sizeof(*ip6));
-		ip6 = (struct ip6 *)(m->m_data + ipoff);
-		ip_hlen = sizeof(*ip6);
-		/* XXX-BZ this will go badly in case of ext hdrs. */
+#ifdef INET6
+	case ETHERTYPE_IPV6: {
+		struct ip6_hdr *ip6;
+
+		m = m_getptr(mp, sizeof(*eh), &hoff);
+		KASSERT(m != NULL && m->m_len - hoff >= sizeof(*ip6));
+		ip6 = (struct ip6_hdr *)(mtod(m, caddr_t) + hoff);
+
+		iphlen = sizeof(*ip6);
 		ipproto = ip6->ip6_nxt;
-		type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_IPV6;
+
+		*type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_IPV6;
 		break;
+	}
 #endif
+
 	default:
-		offload = FALSE;
-		break;
+		panic("CSUM_OUT set for non-IP packet");
+		/* NOTREACHED */
 	}
 
-	vlan_macip_lens |= ip_hlen;
-	type_tucmd_mlhl |= IXGBE_ADVTXD_DCMD_DEXT | IXGBE_ADVTXD_DTYP_CTXT;
+	*vlan_macip_lens |= iphlen;
 
 	switch (ipproto) {
 	case IPPROTO_TCP:
-		if (mp->m_pkthdr.csum_flags & M_TCP_CSUM_OUT)
-			type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_L4T_TCP;
+		KASSERT(ISSET(mp->m_pkthdr.csum_flags, M_TCP_CSUM_OUT));
+		*type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_L4T_TCP;
 		break;
 	case IPPROTO_UDP:
-		if (mp->m_pkthdr.csum_flags & M_UDP_CSUM_OUT)
-			type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_L4T_UDP;
+		KASSERT(ISSET(mp->m_pkthdr.csum_flags, M_UDP_CSUM_OUT));
+		*type_tucmd_mlhl |= IXGBE_ADVTXD_TUCMD_L4T_UDP;
 		break;
 	default:
-		offload = FALSE;
-		break;
+		panic("CSUM_OUT set for wrong protocol");
+		/* NOTREACHED */
+	}
+}
+
+static int
+ixgbe_tx_ctx_setup(struct tx_ring *txr, struct mbuf *mp,
+    uint32_t *cmd_type_len, uint32_t *olinfo_status)
+{
+	struct ixgbe_adv_tx_context_desc *TXD;
+	struct ixgbe_tx_buf *tx_buffer;
+	uint32_t vlan_macip_lens = 0, type_tucmd_mlhl = 0;
+	int	ctxd = txr->next_avail_desc;
+	int	offload = 0;
+
+	/* Indicate the whole packet as payload when not doing TSO */
+	*olinfo_status |= mp->m_pkthdr.len << IXGBE_ADVTXD_PAYLEN_SHIFT;
+
+#if NVLAN > 0
+	if (ISSET(mp->m_flags, M_VLANTAG)) {
+		uint32_t vtag = mp->m_pkthdr.ether_vtag;
+		vlan_macip_lens |= (vtag << IXGBE_ADVTXD_VLAN_SHIFT);
+		*cmd_type_len |= IXGBE_ADVTXD_DCMD_VLE;
+		offload |= 1;
 	}
+#endif
 
-	if (offload) /* For the TX descriptor setup */
+	if (ISSET(mp->m_pkthdr.csum_flags, M_TCP_CSUM_OUT|M_UDP_CSUM_OUT)) {
+		ixgbe_csum_offload(mp, &vlan_macip_lens, &type_tucmd_mlhl);
 		*olinfo_status |= IXGBE_TXD_POPTS_TXSM << 8;
+		offload |= 1;
+	}
+
+	if (!offload)
+		return (0);
+
+	TXD = (struct ixgbe_adv_tx_context_desc *)&txr->tx_base[ctxd];
+	tx_buffer = &txr->tx_buffers[ctxd];
+
+	type_tucmd_mlhl |= IXGBE_ADVTXD_DCMD_DEXT | IXGBE_ADVTXD_DTYP_CTXT;
 
 	/* Now copy bits into descriptor */
 	TXD->vlan_macip_lens = htole32(vlan_macip_lens);