From 413f142cc05cb03f2d1ea83388e40c1ddc0d74e9 Mon Sep 17 00:00:00 2001
From: David Wilder <dwilder@us.ibm.com>
Date: Tue, 13 Oct 2020 16:20:14 -0700
Subject: [PATCH] ibmveth: Identify ingress large send packets.

References: bsc#1178185 ltc#188897
Patch-mainline: v5.10-rc1
Git-commit: 413f142cc05cb03f2d1ea83388e40c1ddc0d74e9

Ingress large send packets are identified by either:
The IBMVETH_RXQ_LRG_PKT flag in the receive buffer
or with a -1 placed in the ip header checksum.
The method used depends on firmware version. Frame
geometry and sufficient header validation is performed by the
hypervisor eliminating the need for further header checks here.

Fixes: 7b5967389f5a ("ibmveth: set correct gso_size and gso_type")
Signed-off-by: David Wilder <dwilder@us.ibm.com>
Reviewed-by: Thomas Falcon <tlfalcon@linux.ibm.com>
Reviewed-by: Cristobal Forno <cris.forno@ibm.com>
Reviewed-by: Pradeep Satyanarayana <pradeeps@linux.vnet.ibm.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 drivers/net/ethernet/ibm/ibmveth.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ibm/ibmveth.c b/drivers/net/ethernet/ibm/ibmveth.c
index 3935a7e22ce5..7ef3369953b6 100644
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c
@@ -1349,6 +1349,7 @@ static int ibmveth_poll(struct napi_struct *napi, int budget)
 			int offset = ibmveth_rxq_frame_offset(adapter);
 			int csum_good = ibmveth_rxq_csum_good(adapter);
 			int lrg_pkt = ibmveth_rxq_large_packet(adapter);
+			__sum16 iph_check = 0;
 
 			skb = ibmveth_rxq_get_buffer(adapter);
 
@@ -1385,7 +1386,17 @@ static int ibmveth_poll(struct napi_struct *napi, int budget)
 			skb_put(skb, length);
 			skb->protocol = eth_type_trans(skb, netdev);
 
-			if (length > netdev->mtu + ETH_HLEN) {
+			/* PHYP without PLSO support places a -1 in the ip
+			 * checksum for large send frames.
+			 */
+			if (skb->protocol == cpu_to_be16(ETH_P_IP)) {
+				struct iphdr *iph = (struct iphdr *)skb->data;
+
+				iph_check = iph->check;
+			}
+
+			if ((length > netdev->mtu + ETH_HLEN) ||
+			    lrg_pkt || iph_check == 0xffff) {
 				ibmveth_rx_mss_helper(skb, mss, lrg_pkt);
 				adapter->rx_large_packets++;
 			}
-- 
2.29.1