[dpdk-dev] [PATCH v5 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 |  3 +++
 lib/librte_gso/gso_common.h            |  5 +++++
 lib/librte_gso/gso_tunnel_tcp4.c       | 14 ++++++++++----
 lib/librte_gso/rte_gso.c               |  8 +++++---
 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 25b8a78..808f537 100644
--- a/doc/guides/rel_notes/release_17_11.rst
+++ b/doc/guides/rel_notes/release_17_11.rst
@@ -51,6 +51,9 @@ New Features
   * VxLAN packets, which must have an outer IPv4 header (prepended by
     an optional VLAN tag), and contain an inner TCP/IPv4 packet (with
     an optional VLAN tag).
+  * GRE packets, which must contain an outer IPv4 header (prepended by
+    an optional VLAN tag), and inner TCP/IPv4 headers (with an optional
+    VLAN tag).
 
   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 c051295..1e99cc0 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 34bbbd7..d79fc6b 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 6095689..b748ab1 100644
--- a/lib/librte_gso/rte_gso.c
+++ b/lib/librte_gso/rte_gso.c
@@ -60,8 +60,9 @@
 
 	if ((gso_ctx->gso_size >= pkt->pkt_len) || (gso_ctx->gso_types &
 				(DEV_TX_OFFLOAD_TCP_TSO |
-				 DEV_TX_OFFLOAD_VXLAN_TNL_TSO)) !=
-				gso_ctx->gso_types) {
+				 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;
 		return 1;
@@ -73,7 +74,8 @@
 	ipid_delta = (gso_ctx->ipid_flag != RTE_GSO_IPID_FIXED);
 	ol_flags = pkt->ol_flags;
 
-	if (IS_IPV4_VXLAN_TCP4(pkt->ol_flags)) {
+	if (IS_IPV4_VXLAN_TCP4(pkt->ol_flags) ||
+			IS_IPV4_GRE_TCP4(pkt->ol_flags)) {
 		pkt->ol_flags &= (~PKT_TX_TCP_SEG);
 		ret = gso_tunnel_tcp4_segment(pkt, gso_size, ipid_delta,
 				direct_pool, indirect_pool,
-- 
1.9.3