From: Julian Wiedmann <jwi@linux.ibm.com>
Subject: s390/qeth: prepare for copy-free TSO transmission
Patch-mainline: v4.20-rc1
Git-commit: e517b649b3c311a8a828b4ee3353bc713e0d5ef0
References: FATE#326377, LTC#169210, bsc#1115382

Summary:        qeth: Full-blown TCP Segmentation Offload
Description:    As of now, qeth only supports TCP Segmentation Offload (TSO)
                for IPv4 in Layer3 devices. This feature extends the existing
                support to IPv6, and adds support for TSO in both IP variants
                for Layer2.

                To cleanly pull in all the necessary changes to the transmit
                code, update the qeth driver to the current 4.20 level.


Upstream-Description:

             s390/qeth: prepare for copy-free TSO transmission

             Add all the necessary TSO plumbing to the copy-less transmit path.
             This includes calculating the right length of required protocol headers,
             and always building a separate buffer element for the TSO headers.

             A follow-up patch will then switch TSO traffic over to this path.

             Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
             Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/net/qeth_core.h      |    1 
 drivers/s390/net/qeth_core_main.c |   10 +++-
 drivers/s390/net/qeth_l2_main.c   |    1 
 drivers/s390/net/qeth_l3_main.c   |   93 +++++++++++++++++++++++++++-----------
 4 files changed, 77 insertions(+), 28 deletions(-)

--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -25,6 +25,7 @@
 #include <net/ipv6.h>
 #include <net/if_inet6.h>
 #include <net/addrconf.h>
+#include <net/tcp.h>
 
 #include <asm/debug.h>
 #include <asm/qdio.h>
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -3841,7 +3841,8 @@ int qeth_hdr_chk_and_bounce(struct sk_bu
 }
 EXPORT_SYMBOL_GPL(qeth_hdr_chk_and_bounce);
 
-#define QETH_HDR_CACHE_OBJ_SIZE		(sizeof(struct qeth_hdr) + ETH_HLEN)
+#define QETH_HDR_CACHE_OBJ_SIZE		(sizeof(struct qeth_hdr_tso) + \
+					 MAX_TCP_HEADER)
 
 /**
  * qeth_add_hw_header() - add a HW header to an skb.
@@ -3876,7 +3877,11 @@ check_layout:
 	if (qeth_get_elements_for_range(start, end + contiguous) == 1) {
 		/* Push HW header into same page as first protocol header. */
 		push_ok = true;
-		__elements = qeth_count_elements(skb, 0);
+		/* ... but TSO always needs a separate element for headers: */
+		if (skb_is_gso(skb))
+			__elements = 1 + qeth_count_elements(skb, proto_len);
+		else
+			__elements = qeth_count_elements(skb, 0);
 	} else if (!proto_len && qeth_get_elements_for_range(start, end) == 1) {
 		/* Push HW header into a new page. */
 		push_ok = true;
@@ -4189,6 +4194,7 @@ int qeth_xmit(struct qeth_card *card, st
 		hd_len = hw_hdr_len + proto_len;
 		data_offset = proto_len;
 	}
+	memset(hdr, 0, hw_hdr_len);
 	fill_header(card, hdr, skb, ipv, cast_type, frame_len);
 
 	is_sg = skb_is_nonlinear(skb);
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -199,7 +199,6 @@ static void qeth_l2_fill_header(struct q
 {
 	struct vlan_ethhdr *veth = (struct vlan_ethhdr *)skb_mac_header(skb);
 
-	memset(hdr, 0, sizeof(struct qeth_hdr));
 	hdr->hdr.l2.id = QETH_HEADER_TYPE_LAYER2;
 	hdr->hdr.l2.pkt_length = data_len;
 
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -2008,7 +2008,6 @@ static void qeth_l3_fill_af_iucv_hdr(str
 	char daddr[16];
 	struct af_iucv_trans_hdr *iucv_hdr;
 
-	memset(hdr, 0, sizeof(struct qeth_hdr));
 	hdr->hdr.l3.id = QETH_HEADER_TYPE_LAYER3;
 	hdr->hdr.l3.length = data_len;
 	hdr->hdr.l3.flags = QETH_HDR_IPV6 | QETH_CAST_UNICAST;
@@ -2038,10 +2037,22 @@ static void qeth_l3_fill_header(struct q
 {
 	struct vlan_ethhdr *veth = vlan_eth_hdr(skb);
 
-	memset(hdr, 0, sizeof(struct qeth_hdr));
-	hdr->hdr.l3.id = QETH_HEADER_TYPE_LAYER3;
 	hdr->hdr.l3.length = data_len;
 
+	if (skb_is_gso(skb)) {
+		hdr->hdr.l3.id = QETH_HEADER_TYPE_TSO;
+	} else {
+		hdr->hdr.l3.id = QETH_HEADER_TYPE_LAYER3;
+		if (skb->ip_summed == CHECKSUM_PARTIAL) {
+			qeth_tx_csum(skb, &hdr->hdr.l3.ext_flags, ipv);
+			/* some HW requires combined L3+L4 csum offload: */
+			if (ipv == 4)
+				hdr->hdr.l3.ext_flags |= QETH_HDR_EXT_CSUM_HDR_REQ;
+			if (card->options.performance_stats)
+				card->perf_stats.tx_csum++;
+		}
+	}
+
 	if (ipv == 4 || IS_IQD(card)) {
 		/* NETIF_F_HW_VLAN_CTAG_TX */
 		if (skb_vlan_tag_present(skb)) {
@@ -2053,15 +2064,6 @@ static void qeth_l3_fill_header(struct q
 		hdr->hdr.l3.vlan_id = ntohs(veth->h_vlan_TCI);
 	}
 
-	if (!skb_is_gso(skb) && skb->ip_summed == CHECKSUM_PARTIAL) {
-		qeth_tx_csum(skb, &hdr->hdr.l3.ext_flags, ipv);
-		/* some HW requires combined L3+L4 csum offload: */
-		if (ipv == 4)
-			hdr->hdr.l3.ext_flags |= QETH_HDR_EXT_CSUM_HDR_REQ;
-		if (card->options.performance_stats)
-			card->perf_stats.tx_csum++;
-	}
-
 	/* OSA only: */
 	if (!ipv) {
 		hdr->hdr.l3.flags = QETH_HDR_PASSTHRU;
@@ -2106,6 +2108,22 @@ static void qeth_l3_fill_header(struct q
 	rcu_read_unlock();
 }
 
+static void qeth_l3_fill_tso_ext(struct qeth_hdr_tso *hdr,
+				 unsigned int payload_len, struct sk_buff *skb,
+				 unsigned int proto_len)
+{
+	struct qeth_hdr_ext_tso *ext = &hdr->ext;
+
+	ext->hdr_tot_len = sizeof(*ext);
+	ext->imb_hdr_no = 1;
+	ext->hdr_type = 1;
+	ext->hdr_version = 1;
+	ext->hdr_len = 28;
+	ext->payload_len = payload_len;
+	ext->mss = skb_shinfo(skb)->gso_size;
+	ext->dg_hdr_len = proto_len;
+}
+
 static void qeth_tso_fill_header(struct qeth_card *card,
 		struct qeth_hdr *qhdr, struct sk_buff *skb)
 {
@@ -2114,8 +2132,6 @@ static void qeth_tso_fill_header(struct
 	struct iphdr *iph = ip_hdr(skb);
 	struct ipv6hdr *ip6h = ipv6_hdr(skb);
 
-	/*fix header to TSO values ...*/
-	hdr->hdr.hdr.l3.id = QETH_HEADER_TYPE_TSO;
 	/*set values which are fix for the first approach ...*/
 	hdr->ext.hdr_tot_len = (__u16) sizeof(struct qeth_hdr_ext_tso);
 	hdr->ext.imb_hdr_no  = 1;
@@ -2179,20 +2195,35 @@ static void qeth_l3_fixup_headers(struct
 	/* this is safe, IPv6 traffic takes a different path */
 	if (skb->ip_summed == CHECKSUM_PARTIAL)
 		iph->check = 0;
+	if (skb_is_gso(skb)) {
+		iph->tot_len = 0;
+		tcp_hdr(skb)->check = ~tcp_v4_check(0, iph->saddr,
+						    iph->daddr, 0);
+	}
 }
 
 static int qeth_l3_xmit_offload(struct qeth_card *card, struct sk_buff *skb,
 				struct qeth_qdio_out_q *queue, int ipv,
 				int cast_type)
 {
-	const unsigned int hw_hdr_len = sizeof(struct qeth_hdr);
-	unsigned int frame_len, elements;
+	unsigned int hw_hdr_len, proto_len, frame_len, elements;
 	unsigned char eth_hdr[ETH_HLEN];
+	bool is_tso = skb_is_gso(skb);
+	unsigned int data_offset = 0;
 	struct qeth_hdr *hdr = NULL;
 	unsigned int hd_len = 0;
 	int push_len, rc;
 	bool is_sg;
 
+	if (is_tso) {
+		hw_hdr_len = sizeof(struct qeth_hdr_tso);
+		proto_len = skb_transport_offset(skb) + tcp_hdrlen(skb) -
+			    ETH_HLEN;
+	} else {
+		hw_hdr_len = sizeof(struct qeth_hdr);
+		proto_len = 0;
+	}
+
 	/* re-use the L2 header area for the HW header: */
 	rc = skb_cow_head(skb, hw_hdr_len - ETH_HLEN);
 	if (rc)
@@ -2202,28 +2233,36 @@ static int qeth_l3_xmit_offload(struct q
 	frame_len = skb->len;
 
 	qeth_l3_fixup_headers(skb);
-	push_len = qeth_add_hw_header(card, skb, &hdr, hw_hdr_len, 0,
+	push_len = qeth_add_hw_header(card, skb, &hdr, hw_hdr_len, proto_len,
 				      &elements);
 	if (push_len < 0)
 		return push_len;
-	if (!push_len) {
-		/* hdr was added discontiguous from skb->data */
-		hd_len = hw_hdr_len;
+	if (is_tso || !push_len) {
+		/* HW header needs its own buffer element. */
+		hd_len = hw_hdr_len + proto_len;
+		data_offset = push_len + proto_len;
 	}
+	memset(hdr, 0, hw_hdr_len);
 
-	if (skb->protocol == htons(ETH_P_AF_IUCV))
+	if (skb->protocol == htons(ETH_P_AF_IUCV)) {
 		qeth_l3_fill_af_iucv_hdr(hdr, skb, frame_len);
-	else
+	} else {
 		qeth_l3_fill_header(card, hdr, skb, ipv, cast_type, frame_len);
+		if (is_tso)
+			qeth_l3_fill_tso_ext((struct qeth_hdr_tso *) hdr,
+					     frame_len - proto_len, skb,
+					     proto_len);
+	}
 
 	is_sg = skb_is_nonlinear(skb);
 	if (IS_IQD(card)) {
-		rc = qeth_do_send_packet_fast(queue, skb, hdr, 0, hd_len);
+		rc = qeth_do_send_packet_fast(queue, skb, hdr, data_offset,
+					      hd_len);
 	} else {
 		/* TODO: drop skb_orphan() once TX completion is fast enough */
 		skb_orphan(skb);
-		rc = qeth_do_send_packet(card, queue, skb, hdr, 0, hd_len,
-					 elements);
+		rc = qeth_do_send_packet(card, queue, skb, hdr, data_offset,
+					 hd_len, elements);
 	}
 
 	if (!rc) {
@@ -2231,6 +2270,10 @@ static int qeth_l3_xmit_offload(struct q
 			card->perf_stats.buf_elements_sent += elements;
 			if (is_sg)
 				card->perf_stats.sg_skbs_sent++;
+			if (is_tso) {
+				card->perf_stats.large_send_bytes += frame_len;
+				card->perf_stats.large_send_cnt++;
+			}
 		}
 	} else {
 		if (!push_len)