diff options
| author | Jon Kohler <jon@nutanix.com> | 2025-11-25 15:27:53 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-11-26 19:45:54 -0800 |
| commit | 1cd1c472343b06d6d32038636ce51bfa2251e3cf (patch) | |
| tree | 6d6bfc0a51eb0cf09c22cea3786b4f155ededd8e /drivers | |
| parent | 6d66e093e0740d39a36ef742c60eec247df26f41 (diff) | |
| download | net-1cd1c472343b06d6d32038636ce51bfa2251e3cf.tar.gz | |
virtio-net: avoid unnecessary checksum calculation on guest RX
Commit a2fb4bc4e2a6 ("net: implement virtio helpers to handle UDP
GSO tunneling.") inadvertently altered checksum offload behavior
for guests not using UDP GSO tunneling.
Before, tun_put_user called tun_vnet_hdr_from_skb, which passed
has_data_valid = true to virtio_net_hdr_from_skb.
After, tun_put_user began calling tun_vnet_hdr_tnl_from_skb instead,
which passes has_data_valid = false into both call sites.
This caused virtio hdr flags to not include VIRTIO_NET_HDR_F_DATA_VALID
for SKBs where skb->ip_summed == CHECKSUM_UNNECESSARY. As a result,
guests are forced to recalculate checksums unnecessarily.
Restore the previous behavior by ensuring has_data_valid = true is
passed in the !tnl_gso_type case, but only from tun side, as
virtio_net_hdr_tnl_from_skb() is used also by the virtio_net driver,
which in turn must not use VIRTIO_NET_HDR_F_DATA_VALID on tx.
cc: stable@vger.kernel.org
Fixes: a2fb4bc4e2a6 ("net: implement virtio helpers to handle UDP GSO tunneling.")
Signed-off-by: Jon Kohler <jon@nutanix.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://patch.msgid.link/20251125222754.1737443-1-jon@nutanix.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/tun_vnet.h | 2 | ||||
| -rw-r--r-- | drivers/net/virtio_net.c | 3 |
2 files changed, 3 insertions, 2 deletions
diff --git a/drivers/net/tun_vnet.h b/drivers/net/tun_vnet.h index 81662328b2c799..a5f93b6c4482c3 100644 --- a/drivers/net/tun_vnet.h +++ b/drivers/net/tun_vnet.h @@ -244,7 +244,7 @@ tun_vnet_hdr_tnl_from_skb(unsigned int flags, if (virtio_net_hdr_tnl_from_skb(skb, tnl_hdr, has_tnl_offload, tun_vnet_is_little_endian(flags), - vlan_hlen)) { + vlan_hlen, true)) { struct virtio_net_hdr_v1 *hdr = &tnl_hdr->hash_hdr.hdr; struct skb_shared_info *sinfo = skb_shinfo(skb); diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 0369dda5ed6068..8e04adb57f52ad 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3339,7 +3339,8 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb, bool orphan) hdr = &skb_vnet_common_hdr(skb)->tnl_hdr; if (virtio_net_hdr_tnl_from_skb(skb, hdr, vi->tx_tnl, - virtio_is_little_endian(vi->vdev), 0)) + virtio_is_little_endian(vi->vdev), 0, + false)) return -EPROTO; if (vi->mergeable_rx_bufs) |