On Fri, 24 Feb 2023 11:11:37 +0800, Jason Wang [off-list ref] wrote:

On Fri, Feb 24, 2023 at 3:38 AM Rob Bradford via B4 Relay
[off-list ref] wrote:

quoted

From: Rob Bradford <redacted>

kvmtool does not support the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature
but does advertise the VIRTIO_NET_F_GUEST_TSO{4,6} features. Check that
the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is present before setting
the NETIF_F_GRO_HW feature bit as otherwise

Here are settings for dev->features and dev->hw_features.

quoted

an attempt will be made to
program the virtio-net device using the ctrl queue which will fail.

This resolves the following error when running on kvmtool:

Can you talk about it in detail what it did?

Thanks.

quoted

[    1.865992] net eth0: Fail to set guest offload.
[    1.872491] virtio_net virtio2 eth0: set_features() failed (-22); wanted 0x0000000000134829, left 0x0080000000134829

Signed-off-by: Rob Bradford <redacted>
---
Changes in v2:
- Use parentheses to group logical OR of features
- Link to v1:
  https://lore.kernel.org/r/20230223-virtio-net-kvmtool-v1-1-fc23d29b9d7a@rivosinc.com (local)
---
 drivers/net/virtio_net.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 61e33e4dd0cd..f8341d1a4ccd 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -3780,10 +3780,9 @@ static int virtnet_probe(struct virtio_device *vdev)
        }
        if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
                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_GRO_HW;
-       if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
+       if ((virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
+           virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6)) &&
+           virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
                dev->hw_features |= NETIF_F_GRO_HW;

Does this mean we won't have NETIF_F_GRO_HW when only TSO4/TSO6 are
supported but not GUEST_OFFLOADS?

Is this intended?

Thanks

quoted

        dev->vlan_features = dev->features;

---
base-commit: c39cea6f38eefe356d64d0bc1e1f2267e282cdd3
change-id: 20230223-virtio-net-kvmtool-87f37515be22

Best regards,
--
Rob Bradford [off-list ref]

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