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>
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index ce1bc57..630a7c1 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -541,6 +541,8 @@
 	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 @@
 			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.
 		 */
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
index 7e76862..9ef9038 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -688,17 +688,15 @@
 		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 */