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.
Fixes: dbcf24d15388 ("virtio-net: use NETIF_F_GRO_HW instead of NETIF_F_LRO")
Signed-off-by: Di Zhu <[email protected]>
---
/* 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 | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 72d6a9c6a5a2..b233c99925e9 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -6781,8 +6781,6 @@ 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 |
@@ -7058,6 +7056,10 @@ static int virtnet_probe(struct virtio_device *vdev)
}
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;
+
rtnl_unlock();
err = virtnet_cpu_notif_add(vi);
--
2.34.1
