[PATCH v2] app/testpmd: perform SW IP checksum for GRO/GSO packets

[Wenwu Ma <wenwux.ma@intel.com>]

The GRO/GSO library doesn't re-calculate checksums for
merged/fragmented packets. If users want the packets to
have correct IP checksums, they should select HW IP
checksum calculation for the port which the packets are
transmitted to. But if the port doesn't support HW IP
checksum, users may perform a SW IP checksum. This patch
add the code about it.

Fixes: b7091f1dcfbc ("app/testpmd: enable the heavyweight mode TCP/IPv4 GRO")
Fixes: 52f38a2055ed ("app/testpmd: enable TCP/IPv4 VxLAN and GRE GSO")
Cc: stable@dpdk.org

Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
---
 app/test-pmd/csumonly.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c
index 8b6665d6f3..e69f31d92c 100644
--- a/app/test-pmd/csumonly.c
+++ b/app/test-pmd/csumonly.c
@@ -778,6 +778,26 @@ pkt_copy_split(const struct rte_mbuf *pkt)
 	return md[0];
 }
 
+/*
+ * Re-calculate IP checksum for merged/fragmented packets.
+ */
+static void
+pkts_ip_csum_recalc(struct rte_mbuf **pkts_burst, const uint16_t nb_pkts, uint64_t tx_offloads)
+{
+	int i;
+	struct rte_ipv4_hdr *ipv4_hdr;
+	for (i = 0; i < nb_pkts; i++) {
+		if ((pkts_burst[i]->ol_flags & RTE_MBUF_F_TX_IPV4) &&
+			(tx_offloads & RTE_ETH_TX_OFFLOAD_IPV4_CKSUM) == 0) {
+			ipv4_hdr = rte_pktmbuf_mtod_offset(pkts_burst[i],
+						struct rte_ipv4_hdr *,
+						pkts_burst[i]->l2_len);
+			ipv4_hdr->hdr_checksum = 0;
+			ipv4_hdr->hdr_checksum = rte_ipv4_cksum(ipv4_hdr);
+		}
+	}
+}
+
 /*
  * Receive a burst of packets, and for each packet:
  *  - parse packet, and try to recognize a supported packet type (1)
@@ -1098,6 +1118,8 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
 				fs->gro_times = 0;
 			}
 		}
+
+		pkts_ip_csum_recalc(pkts_burst, nb_rx, tx_offloads);
 	}
 #endif
 
@@ -1131,6 +1153,8 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
 
 		tx_pkts_burst = gso_segments;
 		nb_rx = nb_segments;
+
+		pkts_ip_csum_recalc(tx_pkts_burst, nb_rx, tx_offloads);
 	} else
 #endif
 		tx_pkts_burst = pkts_burst;
-- 
2.25.1