netdev - [PATCH net v1 3/3] virtio-net: correct hdr

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Message-Id: <20251011094107.16439-4-xuanzhuo@linux.alibaba.com>
Date: Sat, 11 Oct 2025 17:41:07 +0800
From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To: netdev@...r.kernel.org
Cc: "Michael S. Tsirkin" <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Willem de Bruijn <willemb@...gle.com>,
	Jiri Pirko <jiri@...nulli.us>,
	Alvaro Karsz <alvaro.karsz@...id-run.com>,
	Heng Qi <hengqi@...ux.alibaba.com>,
	virtualization@...ts.linux.dev
Subject: [PATCH net v1 3/3] virtio-net: correct hdr_len handling for tunnel gso

The commit a2fb4bc4e2a6a03 ("net: implement virtio helpers to handle UDP
GSO tunneling.") introduces support for the UDP GSO tunnel feature in
virtio-net.

The virtio spec says:

    If the \field{gso_type} has the VIRTIO_NET_HDR_GSO_UDP_TUNNEL_IPV4 bit or
    VIRTIO_NET_HDR_GSO_UDP_TUNNEL_IPV6 bit set, \field{hdr_len} accounts for
    all the headers up to and including the inner transport.

The commit did not update the hdr_len to include the inner transport.

Fixes: a2fb4bc4e2a6a03 ("net: implement virtio helpers to handle UDP GSO tunneling.")
Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
---
 include/linux/virtio_net.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 10ca53b3a399..742cce34a24e 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -403,6 +403,7 @@ virtio_net_hdr_tnl_from_skb(const struct sk_buff *skb,
 	struct virtio_net_hdr *hdr = (struct virtio_net_hdr *)vhdr;
 	unsigned int inner_nh, outer_th;
 	int tnl_gso_type;
+	u16 hdr_len;
 	int ret;
 
 	tnl_gso_type = skb_shinfo(skb)->gso_type & (SKB_GSO_UDP_TUNNEL |
@@ -434,6 +435,23 @@ virtio_net_hdr_tnl_from_skb(const struct sk_buff *skb,
 	outer_th = skb->transport_header - skb_headroom(skb);
 	vhdr->inner_nh_offset = cpu_to_le16(inner_nh);
 	vhdr->outer_th_offset = cpu_to_le16(outer_th);
+
+	switch (skb->inner_ipproto) {
+	case IPPROTO_TCP:
+		hdr_len = inner_tcp_hdrlen(skb);
+		break;
+
+	case IPPROTO_UDP:
+		hdr_len = sizeof(struct udphdr);
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	hdr_len += skb_inner_transport_offset(skb);
+	hdr->hdr_len = __cpu_to_virtio16(little_endian, hdr_len);
+
 	return 0;
 }
 
-- 
2.32.0.3.g01195cf9f