On Mon, Mar 23, 2026 at 12:18 PM Di Zhu [off-list ref] wrote:

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 <redacted>
---
/* 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

Acked-by: Jason Wang <redacted>

Thanks