Negotiating VIRTIO_NET_F_CTRL_GUEST_OFFLOADS indicates the device allows control over offload support, but the offloads that can be controlled may have nothing to do with GRO (e.g., if neither GUEST_TSO4 nor GUEST_TSO6 is supported).
In such a setup, reporting NETIF_F_GRO_HW as available for the device is too optimistic and misleading to the user. Improve the situation by masking off NETIF_F_GRO_HW unless the device possesses actual GRO-related offload capabilities. Out of an abundance of caution, this does not change the current behaviour for hardware with just v6 or just v4 GRO: current interfaces do not allow distinguishing between v6/v4 GRO, so we can't expose them to userspace precisely. Signed-off-by: Di Zhu <[email protected]> --- /* v4 */ -Move the hw_features update logic before register_netdevice() -Target the net-next tree /* v3 */ -Update Fixes tag to dbcf24d15388 -Refine commit message using Maintainer's "too optimistic" phrasing to clarify the risk of misleading configurations. /* v2 */ -make the modified logic clearer --- drivers/net/virtio_net.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 022f60728721..29bd313e7592 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -6795,8 +6795,6 @@ static int virtnet_probe(struct virtio_device *vdev) 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; - if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) - dev->hw_features |= NETIF_F_GRO_HW; dev->vlan_features = dev->features; dev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT | @@ -6989,6 +6987,19 @@ static int virtnet_probe(struct virtio_device *vdev) enable_rx_mode_work(vi); + for (i = 0; i < ARRAY_SIZE(guest_offloads); i++) { + unsigned int fbit; + + fbit = virtio_offload_to_feature(guest_offloads[i]); + if (virtio_has_feature(vi->vdev, fbit)) + set_bit(guest_offloads[i], &vi->guest_offloads); + } + vi->guest_offloads_capable = vi->guest_offloads; + + if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) && + (vi->guest_offloads_capable & GUEST_OFFLOAD_GRO_HW_MASK)) + dev->hw_features |= NETIF_F_GRO_HW; + /* serialize netdev register + virtio_device_ready() with ndo_open() */ rtnl_lock(); @@ -7071,15 +7082,6 @@ static int virtnet_probe(struct virtio_device *vdev) netif_carrier_on(dev); } - for (i = 0; i < ARRAY_SIZE(guest_offloads); i++) { - unsigned int fbit; - - fbit = virtio_offload_to_feature(guest_offloads[i]); - if (virtio_has_feature(vi->vdev, fbit)) - set_bit(guest_offloads[i], &vi->guest_offloads); - } - vi->guest_offloads_capable = vi->guest_offloads; - rtnl_unlock(); err = virtnet_cpu_notif_add(vi); -- 2.34.1
