[PATCH v7 4/6] gso: add GRE GSO support

[Mark Kavanagh <mark.b.kavanagh@intel.com>]

This patch adds GSO support for GRE-tunneled packets. Supported GRE
packets must contain an outer IPv4 header, and inner TCP/IPv4 headers.
They may also contain a single VLAN tag. GRE GSO doesn't check if all
input packets have correct checksums and doesn't update checksums for
output packets. Additionally, it doesn't process IP fragmented packets.

As with VxLAN GSO, GRE GSO uses a two-segment MBUF to organize each
output packet, which requires multi-segment mbuf support in the TX
functions of the NIC driver. Also, if a packet is GSOed, GRE GSO reduces
its MBUF refcnt by 1. As a result, when all of its GSOed segments are
freed, the packet is freed automatically.

Signed-off-by: Mark Kavanagh <mark.b.kavanagh@intel.com>
Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
---
 doc/guides/rel_notes/release_17_11.rst |  2 ++
 lib/librte_gso/gso_common.h            |  5 +++++
 lib/librte_gso/gso_tunnel_tcp4.c       | 14 ++++++++++----
 lib/librte_gso/rte_gso.c               |  9 ++++++---
 4 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/doc/guides/rel_notes/release_17_11.rst b/doc/guides/rel_notes/release_17_11.rst
index c58eeb1..2faa630 100644
--- a/doc/guides/rel_notes/release_17_11.rst
+++ b/doc/guides/rel_notes/release_17_11.rst
@@ -50,6 +50,8 @@ New Features
   * TCP/IPv4 packets.
   * VxLAN packets, which must have an outer IPv4 header, and contain
     an inner TCP/IPv4 packet.
+  * GRE packets, which must contain an outer IPv4 header, and inner
+    TCP/IPv4 headers.
 
   The GSO library doesn't check if the input packets have correct
   checksums, and doesn't update checksums for output packets.
diff --git a/lib/librte_gso/gso_common.h b/lib/librte_gso/gso_common.h
index 95d54e7..145ea49 100644
--- a/lib/librte_gso/gso_common.h
+++ b/lib/librte_gso/gso_common.h
@@ -55,6 +55,11 @@
 		(PKT_TX_TCP_SEG | PKT_TX_IPV4 | PKT_TX_OUTER_IPV4 | \
 		 PKT_TX_TUNNEL_VXLAN))
 
+#define IS_IPV4_GRE_TCP4(flag) (((flag) & (PKT_TX_TCP_SEG | PKT_TX_IPV4 | \
+				PKT_TX_OUTER_IPV4 | PKT_TX_TUNNEL_GRE)) == \
+		(PKT_TX_TCP_SEG | PKT_TX_IPV4 | PKT_TX_OUTER_IPV4 | \
+		 PKT_TX_TUNNEL_GRE))
+
 /**
  * Internal function which updates the UDP header of a packet, following
  * segmentation. This is required to update the header's datagram length field.
diff --git a/lib/librte_gso/gso_tunnel_tcp4.c b/lib/librte_gso/gso_tunnel_tcp4.c
index 5e8c8e5..8d0cfd7 100644
--- a/lib/librte_gso/gso_tunnel_tcp4.c
+++ b/lib/librte_gso/gso_tunnel_tcp4.c
@@ -42,11 +42,13 @@
 	struct tcp_hdr *tcp_hdr;
 	uint32_t sent_seq;
 	uint16_t outer_id, inner_id, tail_idx, i;
-	uint16_t outer_ipv4_offset, inner_ipv4_offset, udp_offset, tcp_offset;
+	uint16_t outer_ipv4_offset, inner_ipv4_offset;
+	uint16_t udp_gre_offset, tcp_offset;
+	uint8_t update_udp_hdr;
 
 	outer_ipv4_offset = pkt->outer_l2_len;
-	udp_offset = outer_ipv4_offset + pkt->outer_l3_len;
-	inner_ipv4_offset = udp_offset + pkt->l2_len;
+	udp_gre_offset = outer_ipv4_offset + pkt->outer_l3_len;
+	inner_ipv4_offset = udp_gre_offset + pkt->l2_len;
 	tcp_offset = inner_ipv4_offset + pkt->l3_len;
 
 	/* Outer IPv4 header. */
@@ -63,9 +65,13 @@
 	sent_seq = rte_be_to_cpu_32(tcp_hdr->sent_seq);
 	tail_idx = nb_segs - 1;
 
+	/* Only update UDP header for VxLAN packets. */
+	update_udp_hdr = (pkt->ol_flags & PKT_TX_TUNNEL_VXLAN) ? 1 : 0;
+
 	for (i = 0; i < nb_segs; i++) {
 		update_ipv4_header(segs[i], outer_ipv4_offset, outer_id);
-		update_udp_header(segs[i], udp_offset);
+		if (update_udp_hdr)
+			update_udp_header(segs[i], udp_gre_offset);
 		update_ipv4_header(segs[i], inner_ipv4_offset, inner_id);
 		update_tcp_header(segs[i], tcp_offset, sent_seq, i < tail_idx);
 		outer_id++;
diff --git a/lib/librte_gso/rte_gso.c b/lib/librte_gso/rte_gso.c
index a6f38e2..1d4082a 100644
--- a/lib/librte_gso/rte_gso.c
+++ b/lib/librte_gso/rte_gso.c
@@ -61,7 +61,8 @@
 	if ((gso_ctx->gso_size < RTE_GSO_SEG_SIZE_MIN) ||
 			(gso_ctx->gso_size >= pkt->pkt_len) ||
 			(gso_ctx->gso_types & (DEV_TX_OFFLOAD_TCP_TSO |
-			                       DEV_TX_OFFLOAD_VXLAN_TNL_TSO)) !=
+			                       DEV_TX_OFFLOAD_VXLAN_TNL_TSO |
+			                       DEV_TX_OFFLOAD_GRE_TNL_TSO)) !=
 			gso_ctx->gso_types) {
 		pkt->ol_flags &= (~PKT_TX_TCP_SEG);
 		pkts_out[0] = pkt;
@@ -74,8 +75,10 @@
 	ipid_delta = (gso_ctx->flag != RTE_GSO_FLAG_IPID_FIXED);
 	ol_flags = pkt->ol_flags;
 
-	if (IS_IPV4_VXLAN_TCP4(pkt->ol_flags)
-		&& (gso_ctx->gso_types & DEV_TX_OFFLOAD_VXLAN_TNL_TSO)) {
+	if ((IS_IPV4_VXLAN_TCP4(pkt->ol_flags) &&
+			(gso_ctx->gso_types & DEV_TX_OFFLOAD_VXLAN_TNL_TSO)) ||
+			((IS_IPV4_GRE_TCP4(pkt->ol_flags) &&
+			 (gso_ctx->gso_types & DEV_TX_OFFLOAD_GRE_TNL_TSO)))) {
 		pkt->ol_flags &= (~PKT_TX_TCP_SEG);
 		ret = gso_tunnel_tcp4_segment(pkt, gso_size, ipid_delta,
 				direct_pool, indirect_pool,
-- 
1.9.3