2 files changed, 71 insertions, 7 deletions

diff --git a/drivers/net/ethernet/hisilicon/hns/hnae.h b/drivers/net/ethernet/hisilicon/hns/hnae.h
index 09602f1187f5..8016854796fb 100644
--- a/drivers/net/ethernet/hisilicon/hns/hnae.h
+++ b/drivers/net/ethernet/hisilicon/hns/hnae.h
@@ -99,6 +99,8 @@ enum hnae_led_state {
 #define HNS_RX_FLAG_L3ID_IPV6 0x1
 #define HNS_RX_FLAG_L4ID_UDP 0x0
 #define HNS_RX_FLAG_L4ID_TCP 0x1
+#define HNS_RX_FLAG_L4ID_SCTP 0x3
+
 
 #define HNS_TXD_ASID_S 0
 #define HNS_TXD_ASID_M (0xff << HNS_TXD_ASID_S)
diff --git a/drivers/net/ethernet/hisilicon/hns/hns_enet.c b/drivers/net/ethernet/hisilicon/hns/hns_enet.c
index 776d81e785d8..672b64606321 100644
--- a/drivers/net/ethernet/hisilicon/hns/hns_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns/hns_enet.c
@@ -566,6 +566,71 @@ static void get_rx_desc_bnum(u32 bnum_flag, int *out_bnum)
 				   HNS_RXD_BUFNUM_M, HNS_RXD_BUFNUM_S);
 }
 
+static void hns_nic_rx_checksum(struct hns_nic_ring_data *ring_data,
+				struct sk_buff *skb, u32 flag)
+{
+	struct net_device *netdev = ring_data->napi.dev;
+	u32 l3id;
+	u32 l4id;
+
+	/* check if RX checksum offload is enabled */
+	if (unlikely(!(netdev->features & NETIF_F_RXCSUM)))
+		return;
+
+	/* In hardware, we only support checksum for the following protocols:
+	 * 1) IPv4,
+	 * 2) TCP(over IPv4 or IPv6),
+	 * 3) UDP(over IPv4 or IPv6),
+	 * 4) SCTP(over IPv4 or IPv6)
+	 * but we support many L3(IPv4, IPv6, MPLS, PPPoE etc) and L4(TCP,
+	 * UDP, GRE, SCTP, IGMP, ICMP etc.) protocols.
+	 *
+	 * Hardware limitation:
+	 * Our present hardware RX Descriptor lacks L3/L4 checksum "Status &
+	 * Error" bit (which usually can be used to indicate whether checksum
+	 * was calculated by the hardware and if there was any error encountered
+	 * during checksum calculation).
+	 *
+	 * Software workaround:
+	 * We do get info within the RX descriptor about the kind of L3/L4
+	 * protocol coming in the packet and the error status. These errors
+	 * might not just be checksum errors but could be related to version,
+	 * length of IPv4, UDP, TCP etc.
+	 * Because there is no-way of knowing if it is a L3/L4 error due to bad
+	 * checksum or any other L3/L4 error, we will not (cannot) convey
+	 * checksum status for such cases to upper stack and will not maintain
+	 * the RX L3/L4 checksum counters as well.
+	 */
+
+	l3id = hnae_get_field(flag, HNS_RXD_L3ID_M, HNS_RXD_L3ID_S);
+	l4id = hnae_get_field(flag, HNS_RXD_L4ID_M, HNS_RXD_L4ID_S);
+
+	/*  check L3 protocol for which checksum is supported */
+	if ((l3id != HNS_RX_FLAG_L3ID_IPV4) && (l3id != HNS_RX_FLAG_L3ID_IPV6))
+		return;
+
+	/* check for any(not just checksum)flagged L3 protocol errors */
+	if (unlikely(hnae_get_bit(flag, HNS_RXD_L3E_B)))
+		return;
+
+	/* we do not support checksum of fragmented packets */
+	if (unlikely(hnae_get_bit(flag, HNS_RXD_FRAG_B)))
+		return;
+
+	/*  check L4 protocol for which checksum is supported */
+	if ((l4id != HNS_RX_FLAG_L4ID_TCP) &&
+	    (l4id != HNS_RX_FLAG_L4ID_UDP) &&
+	    (l4id != HNS_RX_FLAG_L4ID_SCTP))
+		return;
+
+	/* check for any(not just checksum)flagged L4 protocol errors */
+	if (unlikely(hnae_get_bit(flag, HNS_RXD_L4E_B)))
+		return;
+
+	/* now, this has to be a packet with valid RX checksum */
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+}
+
 static int hns_nic_poll_rx_skb(struct hns_nic_ring_data *ring_data,
 			       struct sk_buff **out_skb, int *out_bnum)
 {
@@ -684,13 +749,10 @@ out_bnum_err:
 	ring->stats.rx_pkts++;
 	ring->stats.rx_bytes += skb->len;
 
-	if (unlikely(hnae_get_bit(bnum_flag, HNS_RXD_L3E_B) ||
-		     hnae_get_bit(bnum_flag, HNS_RXD_L4E_B))) {
-		ring->stats.l3l4_csum_err++;
-		return 0;
-	}
-
-	skb->ip_summed = CHECKSUM_UNNECESSARY;
+	/* indicate to upper stack if our hardware has already calculated
+	 * the RX checksum
+	 */
+	hns_nic_rx_checksum(ring_data, skb, bnum_flag);
 
 	return 0;
 }