net: hns3: add support for RX completion checksum

In some cases (for example ip fragment), hardware will
calculate the checksum of whole packet in RX, and setup
the HNS3_RXD_L2_CSUM_B flag in the descriptor, so add
support to utilize this checksum.
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/hisilicon/hns3/hns3_enet.c

@@ -2798,6 +2798,22 @@ static int hns3_gro_complete(struct sk_buff *skb, u32 l234info)
 	return 0;
 }
 
+static void hns3_checksum_complete(struct hns3_enet_ring *ring,
+				   struct sk_buff *skb, u32 l234info)
+{
+	u32 lo, hi;
+
+	u64_stats_update_begin(&ring->syncp);
+	ring->stats.csum_complete++;
+	u64_stats_update_end(&ring->syncp);
+	skb->ip_summed = CHECKSUM_COMPLETE;
+	lo = hnae3_get_field(l234info, HNS3_RXD_L2_CSUM_L_M,
+			     HNS3_RXD_L2_CSUM_L_S);
+	hi = hnae3_get_field(l234info, HNS3_RXD_L2_CSUM_H_M,
+			     HNS3_RXD_L2_CSUM_H_S);
+	skb->csum = csum_unfold((__force __sum16)(lo | hi << 8));
+}
+
 static void hns3_rx_checksum(struct hns3_enet_ring *ring, struct sk_buff *skb,
 			     u32 l234info, u32 bd_base_info, u32 ol_info)
 {
@@ -2812,6 +2828,11 @@ static void hns3_rx_checksum(struct hns3_enet_ring *ring, struct sk_buff *skb,
 	if (!(netdev->features & NETIF_F_RXCSUM))
 		return;
 
+	if (l234info & BIT(HNS3_RXD_L2_CSUM_B)) {
+		hns3_checksum_complete(ring, skb, l234info);
+		return;
+	}
+
 	/* check if hardware has done checksum */
 	if (!(bd_base_info & BIT(HNS3_RXD_L3L4P_B)))
 		return;

drivers/net/ethernet/hisilicon/hns3/hns3_enet.h

@@ -82,6 +82,12 @@ enum hns3_nic_state {
 #define HNS3_RXD_STRP_TAGP_S			13
 #define HNS3_RXD_STRP_TAGP_M			(0x3 << HNS3_RXD_STRP_TAGP_S)
 
+#define HNS3_RXD_L2_CSUM_B			15
+#define HNS3_RXD_L2_CSUM_L_S			4
+#define HNS3_RXD_L2_CSUM_L_M			(0xff << HNS3_RXD_L2_CSUM_L_S)
+#define HNS3_RXD_L2_CSUM_H_S			24
+#define HNS3_RXD_L2_CSUM_H_M			(0xff << HNS3_RXD_L2_CSUM_H_S)
+
 #define HNS3_RXD_L2E_B				16
 #define HNS3_RXD_L3E_B				17
 #define HNS3_RXD_L4E_B				18
@@ -371,6 +377,7 @@ struct ring_stats {
 			u64 err_bd_num;
 			u64 l2_err;
 			u64 l3l4_csum_err;
+			u64 csum_complete;
 			u64 rx_multicast;
 			u64 non_reuse_pg;
 		};

drivers/net/ethernet/hisilicon/hns3/hns3_ethtool.c

@@ -55,6 +55,7 @@ static const struct hns3_stats hns3_rxq_stats[] = {
 	HNS3_TQP_STAT("err_bd_num", err_bd_num),
 	HNS3_TQP_STAT("l2_err", l2_err),
 	HNS3_TQP_STAT("l3l4_csum_err", l3l4_csum_err),
+	HNS3_TQP_STAT("csum_complete", csum_complete),
 	HNS3_TQP_STAT("multicast", rx_multicast),
 	HNS3_TQP_STAT("non_reuse_pg", non_reuse_pg),
 };