Commit a02e8964eaf92 ("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 a02e8964eaf92
("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: a02e8964eaf92 ("virtio-net: ethtool configurable LRO")
Acked-by: Michael S. Tsirkin <[email protected]>
Reported-by: Ivan <[email protected]>
Tested-by: Ivan <[email protected]>
Signed-off-by: Jason Wang <[email protected]>
---
Changes from V1:
- Tweak the commit log
---
 drivers/net/virtio_net.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 0416a7e00914..10c382b08bce 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -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))
@@ -2481,7 +2481,7 @@ 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;
        }
 
@@ -2612,15 +2612,15 @@ 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)
@@ -3100,9 +3100,9 @@ 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;
 
-- 
2.25.1

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