From: Yunsheng Lin <linyunsheng@huawei.com>
Date: Fri, 1 Jun 2018 17:52:09 +0100
Subject: net: hns3: Fix for vxlan tx checksum bug
Patch-mainline: v4.18-rc1
Git-commit: 3db084d28dc04e6ebe9123e0d4f6e8ef5a775ff0
References: bsc#1104353 FATE#326415

when skb->encapsulation is 0, skb->ip_summed is CHECKSUM_PARTIAL
and it is udp packet, which has a dest port as the IANA assigned.
the hardware is expected to do the checksum offload, but the
hardware will not do the checksum offload when udp dest port is
4789.

This patch fixes it by doing the checksum in software.

Fixes: 76ad4f0ee747 ("net: hns3: Add support of HNS3 Ethernet Driver for hip08 SoC")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/hisilicon/hns3/hns3_enet.c |   29 ++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -654,6 +654,32 @@ static void hns3_set_l2l3l4_len(struct s
 	}
 }
 
+/* when skb->encapsulation is 0, skb->ip_summed is CHECKSUM_PARTIAL
+ * and it is udp packet, which has a dest port as the IANA assigned.
+ * the hardware is expected to do the checksum offload, but the
+ * hardware will not do the checksum offload when udp dest port is
+ * 4789.
+ */
+static bool hns3_tunnel_csum_bug(struct sk_buff *skb)
+{
+#define IANA_VXLAN_PORT	4789
+	union {
+		struct tcphdr *tcp;
+		struct udphdr *udp;
+		struct gre_base_hdr *gre;
+		unsigned char *hdr;
+	} l4;
+
+	l4.hdr = skb_transport_header(skb);
+
+	if (!(!skb->encapsulation && l4.udp->dest == htons(IANA_VXLAN_PORT)))
+		return false;
+
+	skb_checksum_help(skb);
+
+	return true;
+}
+
 static int hns3_set_l3l4_type_csum(struct sk_buff *skb, u8 ol4_proto,
 				   u8 il4_proto, u32 *type_cs_vlan_tso,
 				   u32 *ol_type_vlan_len_msec)
@@ -742,6 +768,9 @@ static int hns3_set_l3l4_type_csum(struc
 			       HNS3_L4T_TCP);
 		break;
 	case IPPROTO_UDP:
+		if (hns3_tunnel_csum_bug(skb))
+			break;
+
 		hnae_set_field(*type_cs_vlan_tso,
 			       HNS3_TXD_L4T_M,
 			       HNS3_TXD_L4T_S,