[PATCH v2 2/2][Bionic][SRU Artful] net: thunderx: Fix TCP/UDP checksum offload for IPv4 pkts

[dann frazier]

From: Florian Westphal <fw at strlen.de>

BugLink: https://bugs.launchpad.net/bugs/1736593

Offload IP header checksum to NIC.

This fixes a previous patch which disabled checksum offloading
for both IPv4 and IPv6 packets.  So L3 checksum offload was
getting disabled for IPv4 pkts.  And HW is dropping these pkts
for some reason.

Without this patch, IPv4 TSO appears to be broken:

WIthout this patch I get ~16kbyte/s, with patch close to 2mbyte/s
when copying files via scp from test box to my home workstation.

Looking at tcpdump on sender it looks like hardware drops IPv4 TSO skbs.
This patch restores performance for me, ipv6 looks good too.

Fixes: fa6d7cb5d76c ("net: thunderx: Fix TCP/UDP checksum offload for IPv6 pkts")
Cc: Sunil Goutham <sgoutham at cavium.com>
Cc: Aleksey Makarov <aleksey.makarov at auriga.com>
Cc: Eric Dumazet <edumazet at google.com>
Signed-off-by: Florian Westphal <fw at strlen.de>
Signed-off-by: David S. Miller <davem at davemloft.net>
(cherry picked from commit 134059fd2775be79e26c2dff87d25cc2f6ea5626)
Signed-off-by: dann frazier <dann.frazier at canonical.com>
---
 drivers/net/ethernet/cavium/thunder/nicvf_queues.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
index 8b2c31e2a2b0..a3d12dbde95b 100644
--- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
@@ -1355,6 +1355,8 @@ nicvf_sq_add_hdr_subdesc(struct nicvf *nic, struct snd_queue *sq, int qentry,
 
 	/* Offload checksum calculation to HW */
 	if (skb->ip_summed == CHECKSUM_PARTIAL) {
+		if (ip.v4->version == 4)
+			hdr->csum_l3 = 1; /* Enable IP csum calculation */
 		hdr->l3_offset = skb_network_offset(skb);
 		hdr->l4_offset = skb_transport_offset(skb);
 
-- 
2.15.1