mlx4_en: Allow communication between functions on same host

To enable internal loopback, always fill DMAC in control segment
when transmitting the packet, once this is done, the packet is subject
for loopback for if the DMAC mathces one of the multicast/unicast addresses
registered on the physical port.
In receive path if source MAC is our own MAC and we are not in selftest,
or not in force LB mode - drop this packet.
Signed-off-by: Eugenia Emantayev <eugenia@mellanox.co.il>
Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_rx.c

@@ -541,6 +541,8 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
 	unsigned int length;
 	int polled = 0;
 	int ip_summed;
+	struct ethhdr *ethh;
+	u64 s_mac;
 
 	if (!priv->port_up)
 		return 0;
@@ -577,6 +579,19 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
 			goto next;
 		}
 
+		/* Get pointer to first fragment since we haven't skb yet and
+		 * cast it to ethhdr struct */
+		ethh = (struct ethhdr *)(page_address(skb_frags[0].page) +
+					 skb_frags[0].offset);
+		s_mac = mlx4_en_mac_to_u64(ethh->h_source);
+
+		/* If source MAC is equal to our own MAC and not performing
+		 * the selftest or flb disabled - drop the packet */
+		if (s_mac == priv->mac &&
+			(!(dev->features & NETIF_F_LOOPBACK) ||
+			 !priv->validate_loopback))
+			goto next;
+
 		/*
 		 * Packet is OK - process it.
 		 */

drivers/net/ethernet/mellanox/mlx4/en_tx.c

@@ -688,17 +688,15 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
 		ring->tx_csum++;
 	}
 
-	if (unlikely(priv->validate_loopback)) {
-		/* Copy dst mac address to wqe */
-		skb_reset_mac_header(skb);
-		ethh = eth_hdr(skb);
-		if (ethh && ethh->h_dest) {
-			mac = mlx4_en_mac_to_u64(ethh->h_dest);
-			mac_h = (u32) ((mac & 0xffff00000000ULL) >> 16);
-			mac_l = (u32) (mac & 0xffffffff);
-			tx_desc->ctrl.srcrb_flags |= cpu_to_be32(mac_h);
-			tx_desc->ctrl.imm = cpu_to_be32(mac_l);
-		}
+	/* Copy dst mac address to wqe */
+	skb_reset_mac_header(skb);
+	ethh = eth_hdr(skb);
+	if (ethh && ethh->h_dest) {
+		mac = mlx4_en_mac_to_u64(ethh->h_dest);
+		mac_h = (u32) ((mac & 0xffff00000000ULL) >> 16);
+		mac_l = (u32) (mac & 0xffffffff);
+		tx_desc->ctrl.srcrb_flags |= cpu_to_be32(mac_h);
+		tx_desc->ctrl.imm = cpu_to_be32(mac_l);
 	}
 
 	/* Handle LSO (TSO) packets */