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Commit da92ce36 authored by Jason Wang's avatar Jason Wang Committed by Sasha Levin
Browse files

virtio-net: use NETIF_F_GRO_HW instead of NETIF_F_LRO 



[ Upstream commit dbcf24d153884439dad30484a0e3f02350692e4c ]

Commit a02e8964 ("virtio-net: ethtool configurable LRO")
maps LRO to virtio guest offloading features and allows the
administrator to enable and disable those features via ethtool.

This leads to several issues:

- For a device that doesn't support control guest offloads, the "LRO"
  can't be disabled triggering WARN in dev_disable_lro() when turning
  off LRO or when enabling forwarding bridging etc.

- For a device that supports control guest offloads, the guest
  offloads are disabled in cases of bridging, forwarding etc slowing
  down the traffic.

Fix this by using NETIF_F_GRO_HW instead. Though the spec does not
guarantee packets to be re-segmented as the original ones,
we can add that to the spec, possibly with a flag for devices to
differentiate between GRO and LRO.

Further, we never advertised LRO historically before a02e8964
("virtio-net: ethtool configurable LRO") and so bridged/forwarded
configs effectively always relied on virtio receive offloads behaving
like GRO - thus even if this breaks any configs it is at least not
a regression.

Fixes: a02e8964 ("virtio-net: ethtool configurable LRO")
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reported-by: default avatarIvan <ivan@prestigetransportation.com>
Tested-by: default avatarIvan <ivan@prestigetransportation.com>
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 9aeadce8

drivers/net/virtio_net.c

+7 −7
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ static const unsigned long guest_offloads[] = { 
	VIRTIO_NET_F_GUEST_CSUM

};



#define GUEST_OFFLOAD_LRO_MASK ((1ULL << VIRTIO_NET_F_GUEST_TSO4) | \

#define GUEST_OFFLOAD_GRO_HW_MASK ((1ULL << VIRTIO_NET_F_GUEST_TSO4) | \

				(1ULL << VIRTIO_NET_F_GUEST_TSO6) | \

				(1ULL << VIRTIO_NET_F_GUEST_ECN)  | \

				(1ULL << VIRTIO_NET_F_GUEST_UFO))
@@ -2493,7 +2493,7 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, 
	        virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||

		virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO) ||

		virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))) {

		NL_SET_ERR_MSG_MOD(extack, "Can't set XDP while host is implementing LRO/CSUM, disable LRO/CSUM first");

		NL_SET_ERR_MSG_MOD(extack, "Can't set XDP while host is implementing GRO_HW/CSUM, disable GRO_HW/CSUM first");

		return -EOPNOTSUPP;

	}
@@ -2644,15 +2644,15 @@ static int virtnet_set_features(struct net_device *dev, 
	u64 offloads;

	int err;



	if ((dev->features ^ features) & NETIF_F_LRO) {

	if ((dev->features ^ features) & NETIF_F_GRO_HW) {

		if (vi->xdp_enabled)

			return -EBUSY;



		if (features & NETIF_F_LRO)

		if (features & NETIF_F_GRO_HW)

			offloads = vi->guest_offloads_capable;

		else

			offloads = vi->guest_offloads_capable &

				   ~GUEST_OFFLOAD_LRO_MASK;

				   ~GUEST_OFFLOAD_GRO_HW_MASK;



		err = virtnet_set_guest_offloads(vi, offloads);

		if (err)
@@ -3128,9 +3128,9 @@ static int virtnet_probe(struct virtio_device *vdev) 
		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_LRO;

		dev->features |= NETIF_F_GRO_HW;

	if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))

		dev->hw_features |= NETIF_F_LRO;

		dev->hw_features |= NETIF_F_GRO_HW;



	dev->vlan_features = dev->features;