From: jan@openbsd.org
Subject: Re: igc(4) tso
To: Moritz Buhl <mbuhl@openbsd.org>
Cc: tech@openbsd.org, bket@openbsd.org, bluhm@openbsd.org
Date: Thu, 2 May 2024 21:27:07 +0200

On Thu, May 02, 2024 at 08:51:26PM GMT, Moritz Buhl wrote:
> I addressed your comment and also noticed that the diff broke with
> previous convention of using the ISSET macro.
> 
> Is this ok?

After talking with bluhm.  We come to the conclusion, that this diff
is better:

Index: dev/pci//if_igc.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/if_igc.c,v
diff -u -p -r1.20 if_igc.c
--- dev/pci//if_igc.c	12 Apr 2024 19:27:43 -0000	1.20
+++ dev/pci//if_igc.c	2 May 2024 18:55:11 -0000
@@ -44,10 +44,14 @@
 
 #include <net/if.h>
 #include <net/if_media.h>
+#include <net/route.h>
 #include <net/toeplitz.h>
 
 #include <netinet/in.h>
 #include <netinet/if_ether.h>
+#include <netinet/tcp.h>
+#include <netinet/tcp_timer.h>
+#include <netinet/tcp_var.h>
 
 #if NBPFILTER > 0
 #include <net/bpf.h>
@@ -796,6 +800,7 @@ igc_setup_interface(struct igc_softc *sc
 	ifp->if_capabilities |= IFCAP_CSUM_IPv4;
 	ifp->if_capabilities |= IFCAP_CSUM_TCPv4 | IFCAP_CSUM_UDPv4;
 	ifp->if_capabilities |= IFCAP_CSUM_TCPv6 | IFCAP_CSUM_UDPv6;
+	ifp->if_capabilities |= IFCAP_TSOv4 | IFCAP_TSOv6;
 
 	/* Initialize ifmedia structures. */
 	ifmedia_init(&sc->media, IFM_IMASK, igc_media_change, igc_media_status);
@@ -2025,13 +2030,11 @@ igc_tx_ctx_setup(struct tx_ring *txr, st
 {
 	struct ether_extracted ext;
 	struct igc_adv_tx_context_desc *txdesc;
+	uint32_t mss_l4len_idx = 0;
 	uint32_t type_tucmd_mlhl = 0;
 	uint32_t vlan_macip_lens = 0;
 	int off = 0;
 
-	ether_extract_headers(mp, &ext);
-	vlan_macip_lens |= (sizeof(*ext.eh) << IGC_ADVTXD_MACLEN_SHIFT);
-
 	/*
 	 * In advanced descriptors the vlan tag must
 	 * be placed into the context descriptor. Hence
@@ -2046,6 +2049,10 @@ igc_tx_ctx_setup(struct tx_ring *txr, st
 	}
 #endif
 
+	ether_extract_headers(mp, &ext);
+
+	vlan_macip_lens |= (sizeof(*ext.eh) << IGC_ADVTXD_MACLEN_SHIFT);
+
 	if (ext.ip4) {
 		type_tucmd_mlhl |= IGC_ADVTXD_TUCMD_IPV4;
 		if (ISSET(mp->m_pkthdr.csum_flags, M_IPV4_CSUM_OUT)) {
@@ -2056,6 +2063,9 @@ igc_tx_ctx_setup(struct tx_ring *txr, st
 	} else if (ext.ip6) {
 		type_tucmd_mlhl |= IGC_ADVTXD_TUCMD_IPV6;
 #endif
+	} else {
+		if (mp->m_pkthdr.csum_flags & M_TCP_TSO)
+			tcpstat_inc(tcps_outbadtso);
 	}
 
 	vlan_macip_lens |= ext.iphlen;
@@ -2075,6 +2085,30 @@ igc_tx_ctx_setup(struct tx_ring *txr, st
 		}
 	}
 
+	if (mp->m_pkthdr.csum_flags & M_TCP_TSO) {
+		if (ext.tcp) {
+			uint32_t hdrlen, thlen, paylen, outlen;
+
+			thlen = ext.tcphlen;
+
+			outlen = mp->m_pkthdr.ph_mss;
+			mss_l4len_idx |= outlen << IGC_ADVTXD_MSS_SHIFT;
+			mss_l4len_idx |= thlen << IGC_ADVTXD_L4LEN_SHIFT;
+
+			hdrlen = sizeof(*ext.eh) + ext.iphlen + thlen;
+			paylen = mp->m_pkthdr.len - hdrlen;
+			CLR(*olinfo_status, IGC_ADVTXD_PAYLEN_MASK);
+			*olinfo_status |= paylen << IGC_ADVTXD_PAYLEN_SHIFT;
+
+			*cmd_type_len |= IGC_ADVTXD_DCMD_TSE;
+			off = 1;
+
+			tcpstat_add(tcps_outpkttso,
+			    (paylen + outlen - 1) / outlen);
+		} else
+			tcpstat_inc(tcps_outbadtso);
+	}
+
 	if (off == 0)
 		return 0;
 
@@ -2085,7 +2119,7 @@ igc_tx_ctx_setup(struct tx_ring *txr, st
 	htolem32(&txdesc->vlan_macip_lens, vlan_macip_lens);
 	htolem32(&txdesc->type_tucmd_mlhl, type_tucmd_mlhl);
 	htolem32(&txdesc->seqnum_seed, 0);
-	htolem32(&txdesc->mss_l4len_idx, 0);
+	htolem32(&txdesc->mss_l4len_idx, mss_l4len_idx);
 
 	return 1;
 }
Index: dev/pci//igc_base.h
===================================================================
RCS file: /cvs/src/sys/dev/pci/igc_base.h,v
diff -u -p -r1.2 igc_base.h
--- dev/pci//igc_base.h	25 Mar 2024 20:25:13 -0000	1.2
+++ dev/pci//igc_base.h	2 May 2024 19:20:23 -0000
@@ -66,6 +66,7 @@ struct igc_adv_tx_context_desc {
 #define IGC_ADVTXD_POPTS_ISCO_FULL	0x00001800
 #define IGC_ADVTXD_POPTS_IPSEC	0x00000400 /* IPSec offload request */
 #define IGC_ADVTXD_PAYLEN_SHIFT	14 /* Adv desc PAYLEN shift */
+#define IGC_ADVTXD_PAYLEN_MASK	0xFFFFD000 /* Adv desc PAYLEN mask */
 
 /* Advanced Transmit Context Descriptor Config */
 #define IGC_ADVTXD_MACLEN_SHIFT		9 /* Adv ctxt desc mac len shift */