[PATCH net] virtio-net: clear NETIF_F_GRO_HW if no GRO-related offloads are capable

[Di Zhu]

Although VIRTIO_NET_F_CTRL_GUEST_OFFLOADS is negotiated, which indicates
the device supports dynamic control of guest offloads, it does not
necessarily mean the device supports specific hardware GRO features.

If none of the features defined in GUEST_OFFLOAD_GRO_HW_MASK (such as
TSO4, TSO6, or UFO) are present in vi->guest_offloads_capable, the
device effectively lacks the hardware capability to perform GRO.

In this case, NETIF_F_GRO_HW should be cleared from dev->hw_features
to prevent the stack from attempting to enable an unsupported
hardware offload configuration.

Fixes: a02e8964eaf9 ("virtio-net: ethtool configurable LRO")
Signed-off-by: Di Zhu <z...@hygon.cn>
---
 drivers/net/virtio_net.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 72d6a9c6a5a2..49a60af684d5 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -7058,6 +7058,9 @@ static int virtnet_probe(struct virtio_device *vdev)
        }
        vi->guest_offloads_capable = vi->guest_offloads;
 
+       if (!(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