net: ena: use CSUM_CHECKED device indication to report skb's checksum status

BugLink: http://bugs.launchpad.net/bugs/1798182

Set skb->ip_summed to the correct value as reported by the device.
Add counter for the case where rx csum offload is enabled but
device didn't check it.
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit cb36bb36 linux-next)
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/net/ethernet/amazon/ena/ena_eth_com.c

@@ -354,6 +354,9 @@ static inline void ena_com_rx_set_flags(struct ena_com_rx_ctx *ena_rx_ctx,
 	ena_rx_ctx->l4_csum_err =
 		!!((cdesc->status & ENA_ETH_IO_RX_CDESC_BASE_L4_CSUM_ERR_MASK) >>
 		ENA_ETH_IO_RX_CDESC_BASE_L4_CSUM_ERR_SHIFT);
+	ena_rx_ctx->l4_csum_checked =
+		!!((cdesc->status & ENA_ETH_IO_RX_CDESC_BASE_L4_CSUM_CHECKED_MASK) >>
+		ENA_ETH_IO_RX_CDESC_BASE_L4_CSUM_CHECKED_SHIFT);
 	ena_rx_ctx->hash = cdesc->hash;
 	ena_rx_ctx->frag =
 		(cdesc->status & ENA_ETH_IO_RX_CDESC_BASE_IPV4_FRAG_MASK) >>

drivers/net/ethernet/amazon/ena/ena_eth_com.h

@@ -67,6 +67,7 @@ struct ena_com_rx_ctx {
 	enum ena_eth_io_l4_proto_index l4_proto;
 	bool l3_csum_err;
 	bool l4_csum_err;
+	u8 l4_csum_checked;
 	/* fragmented packet */
 	bool frag;
 	u32 hash;

drivers/net/ethernet/amazon/ena/ena_eth_io_defs.h

@@ -242,9 +242,13 @@ struct ena_eth_io_rx_cdesc_base {
 	 *    checksum error detected, or, the controller didn't
 	 *    validate the checksum. This bit is valid only when
 	 *    l4_proto_idx indicates TCP/UDP packet, and,
-	 *    ipv4_frag is not set
+	 *    ipv4_frag is not set. This bit is valid only when
+	 *    l4_csum_checked below is set.
 	 * 15 : ipv4_frag - Indicates IPv4 fragmented packet
-	 * 23:16 : reserved16
+	 * 16 : l4_csum_checked - L4 checksum was verified
+	 *    (could be OK or error), when cleared the status of
+	 *    checksum is unknown
+	 * 23:17 : reserved17 - MBZ
 	 * 24 : phase
 	 * 25 : l3_csum2 - second checksum engine result
 	 * 26 : first - Indicates first descriptor in
@@ -390,6 +394,8 @@ struct ena_eth_io_numa_node_cfg_reg {
 #define ENA_ETH_IO_RX_CDESC_BASE_L4_CSUM_ERR_MASK BIT(14)
 #define ENA_ETH_IO_RX_CDESC_BASE_IPV4_FRAG_SHIFT 15
 #define ENA_ETH_IO_RX_CDESC_BASE_IPV4_FRAG_MASK BIT(15)
+#define ENA_ETH_IO_RX_CDESC_BASE_L4_CSUM_CHECKED_SHIFT 16
+#define ENA_ETH_IO_RX_CDESC_BASE_L4_CSUM_CHECKED_MASK BIT(16)
 #define ENA_ETH_IO_RX_CDESC_BASE_PHASE_SHIFT 24
 #define ENA_ETH_IO_RX_CDESC_BASE_PHASE_MASK BIT(24)
 #define ENA_ETH_IO_RX_CDESC_BASE_L3_CSUM2_SHIFT 25

drivers/net/ethernet/amazon/ena/ena_ethtool.c

@@ -97,6 +97,7 @@ static const struct ena_stats ena_stats_rx_strings[] = {
 	ENA_STAT_RX_ENTRY(rx_copybreak_pkt),
 	ENA_STAT_RX_ENTRY(bad_req_id),
 	ENA_STAT_RX_ENTRY(empty_rx_ring),
+	ENA_STAT_RX_ENTRY(csum_unchecked),
 };
 
 static const struct ena_stats ena_stats_ena_com_strings[] = {

drivers/net/ethernet/amazon/ena/ena_netdev.c

@@ -1002,8 +1002,19 @@ static inline void ena_rx_checksum(struct ena_ring *rx_ring,
 			return;
 		}
 
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
+		if (likely(ena_rx_ctx->l4_csum_checked)) {
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
+		} else {
+			u64_stats_update_begin(&rx_ring->syncp);
+			rx_ring->rx_stats.csum_unchecked++;
+			u64_stats_update_end(&rx_ring->syncp);
+			skb->ip_summed = CHECKSUM_NONE;
+		}
+	} else {
+		skb->ip_summed = CHECKSUM_NONE;
+		return;
 	}
+
 }
 
 static void ena_set_rx_hash(struct ena_ring *rx_ring,

drivers/net/ethernet/amazon/ena/ena_netdev.h

@@ -202,6 +202,7 @@ struct ena_stats_rx {
 	u64 rx_copybreak_pkt;
 	u64 bad_req_id;
 	u64 empty_rx_ring;
+	u64 csum_unchecked;
 };
 
 struct ena_ring {