diff options
| author | Heng Qi <hengqi@linux.alibaba.com> | 2024-06-17 21:15:23 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-07-05 09:12:39 +0200 |
| commit | 333c0a1f7d5bb506d169d56005299e2b1c07ff8e (patch) | |
| tree | 178d85bb87a41e60e329934b8d2ca560dfdcbbc9 /drivers | |
| parent | b4bca4722fda928810d024350493990de39f1e40 (diff) | |
virtio_net: checksum offloading handling fix
[ Upstream commit 604141c036e1b636e2a71cf6e1aa09d1e45f40c2 ]
In virtio spec 0.95, VIRTIO_NET_F_GUEST_CSUM was designed to handle
partially checksummed packets, and the validation of fully checksummed
packets by the device is independent of VIRTIO_NET_F_GUEST_CSUM
negotiation. However, the specification erroneously stated:
"If VIRTIO_NET_F_GUEST_CSUM is not negotiated, the device MUST set flags
to zero and SHOULD supply a fully checksummed packet to the driver."
This statement is inaccurate because even without VIRTIO_NET_F_GUEST_CSUM
negotiation, the device can still set the VIRTIO_NET_HDR_F_DATA_VALID flag.
Essentially, the device can facilitate the validation of these packets'
checksums - a process known as RX checksum offloading - removing the need
for the driver to do so.
This scenario is currently not implemented in the driver and requires
correction. The necessary specification correction[1] has been made and
approved in the virtio TC vote.
[1] https://lists.oasis-open.org/archives/virtio-comment/202401/msg00011.html
Fixes: 4f49129be6fa ("virtio-net: Set RXCSUM feature if GUEST_CSUM is available")
Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/virtio_net.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 4029c56dfcf0..f7ed99561c19 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3112,8 +3112,16 @@ static int virtnet_probe(struct virtio_device *vdev) dev->features |= dev->hw_features & NETIF_F_ALL_TSO; /* (!csum && gso) case will be fixed by register_netdev() */ } - if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM)) - dev->features |= NETIF_F_RXCSUM; + + /* 1. With VIRTIO_NET_F_GUEST_CSUM negotiation, the driver doesn't + * need to calculate checksums for partially checksummed packets, + * as they're considered valid by the upper layer. + * 2. Without VIRTIO_NET_F_GUEST_CSUM negotiation, the driver only + * receives fully checksummed packets. The device may assist in + * validating these packets' checksums, so the driver won't have to. + */ + dev->features |= NETIF_F_RXCSUM; + if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) || virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6)) dev->features |= NETIF_F_GRO_HW; |