net/mlx5e: Fix UDP GSO for encapsulated packets

When the skb is encapsulated, adjust the inner UDP header instead of the
outer one, and account for UDP header (instead of TCP) in the inline
header size calculation.

Fixes: 689adf0d ("net/mlx5e: Add UDP GSO support")
Reported-by: Jason Baron <jbaron@akamai.com>
Closes: https://lore.kernel.org/netdev/c42961cb-50b9-4a9a-bd43-87fe48d88d29@akamai.com/Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Boris Pismenny <borisp@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/en_accel/en_accel.h

@@ -102,8 +102,14 @@ static inline void
 mlx5e_udp_gso_handle_tx_skb(struct sk_buff *skb)
 {
 	int payload_len = skb_shinfo(skb)->gso_size + sizeof(struct udphdr);
+	struct udphdr *udphdr;
 
-	udp_hdr(skb)->len = htons(payload_len);
+	if (skb->encapsulation)
+		udphdr = (struct udphdr *)skb_inner_transport_header(skb);
+	else
+		udphdr = udp_hdr(skb);
+
+	udphdr->len = htons(payload_len);
 }
 
 struct mlx5e_accel_tx_state {

drivers/net/ethernet/mellanox/mlx5/core/en_tx.c

@@ -153,7 +153,11 @@ mlx5e_tx_get_gso_ihs(struct mlx5e_txqsq *sq, struct sk_buff *skb, int *hopbyhop)
 
 	*hopbyhop = 0;
 	if (skb->encapsulation) {
-		ihs = skb_inner_tcp_all_headers(skb);
+		if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
+			ihs = skb_inner_transport_offset(skb) +
+			      sizeof(struct udphdr);
+		else
+			ihs = skb_inner_tcp_all_headers(skb);
 		stats->tso_inner_packets++;
 		stats->tso_inner_bytes += skb->len - ihs;
 	} else {