[PATCH net-next] gve: add support for UDP GSO for DQO format

[Harshitha Ramamurthy <hramamurthy@google.com>]

From: Ankit Garg <nktgrg@google.com>

Enable support for UDP GSO when using DQO format. Advertise the feature
flag during device initialization and enable offload by default.

Signed-off-by: Ankit Garg <nktgrg@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
---
 drivers/net/ethernet/google/gve/gve_adminq.c |  8 +++++---
 drivers/net/ethernet/google/gve/gve_tx_dqo.c | 33 ++++++++++++++++++++++++---------
 2 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_adminq.c b/drivers/net/ethernet/google/gve/gve_adminq.c
index 6ce8345e..f27b9501 100644
--- a/drivers/net/ethernet/google/gve/gve_adminq.c
+++ b/drivers/net/ethernet/google/gve/gve_adminq.c
@@ -1127,10 +1127,12 @@ int gve_adminq_describe_device(struct gve_priv *priv)
 
 	gve_set_default_rss_sizes(priv);
 
-	/* DQO supports HW-GRO. */
+	/* DQO supports HW-GRO and UDP_GSO */
 	if (gve_is_dqo(priv)) {
-		priv->dev->hw_features |= NETIF_F_GRO_HW;
-		priv->dev->features |= NETIF_F_GRO_HW;
+		u64 additional_features = NETIF_F_GRO_HW | NETIF_F_GSO_UDP_L4;
+
+		priv->dev->hw_features |= additional_features;
+		priv->dev->features |= additional_features;
 	}
 
 	priv->max_registered_pages =
diff --git a/drivers/net/ethernet/google/gve/gve_tx_dqo.c b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
index 28e85730..81d27a12 100644
--- a/drivers/net/ethernet/google/gve/gve_tx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
@@ -565,9 +565,11 @@ static void gve_tx_fill_pkt_desc_dqo(struct gve_tx_ring *tx, u32 *desc_idx,
  */
 static int gve_prep_tso(struct sk_buff *skb)
 {
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+	u32 paylen, l4_start;
 	struct tcphdr *tcp;
+	struct udphdr *udp;
 	int header_len;
-	u32 paylen;
 	int err;
 
 	/* Note: HW requires MSS (gso_size) to be <= 9728 and the total length
@@ -578,21 +580,34 @@ static int gve_prep_tso(struct sk_buff *skb)
 	 * - Kernel will not produce a TSO larger than 64k
 	 */
 
-	if (unlikely(skb_shinfo(skb)->gso_size < GVE_TX_MIN_TSO_MSS_DQO))
+	if (unlikely(shinfo->gso_size < GVE_TX_MIN_TSO_MSS_DQO))
 		return -1;
 
-	if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
-		return -EINVAL;
-
 	/* Needed because we will modify header. */
 	err = skb_cow_head(skb, 0);
 	if (err < 0)
 		return err;
 
-	tcp = tcp_hdr(skb);
-	paylen = skb->len - skb_transport_offset(skb);
-	csum_replace_by_diff(&tcp->check, (__force __wsum)htonl(paylen));
-	header_len = skb_tcp_all_headers(skb);
+	l4_start = skb_transport_offset(skb);
+	paylen = skb->len - l4_start;
+
+	switch (shinfo->gso_type) {
+	case SKB_GSO_TCPV4:
+	case SKB_GSO_TCPV6:
+		tcp = tcp_hdr(skb);
+		csum_replace_by_diff(&tcp->check,
+				     (__force __wsum)htonl(paylen));
+		header_len = skb_tcp_all_headers(skb);
+		break;
+	case SKB_GSO_UDP_L4:
+		udp = udp_hdr(skb);
+		csum_replace_by_diff(&udp->check,
+				     (__force __wsum)htonl(paylen));
+		header_len = sizeof(struct udphdr) + l4_start;
+		break;
+	default:
+		return -EINVAL;
+	}
 
 	if (unlikely(header_len > GVE_TX_MAX_HDR_SIZE_DQO))
 		return -EINVAL;
-- 
2.53.0.473.g4a7958ca14-goog