Re: [PATCH net] virtio-net: drop the multi-buffer XDP packet in zerocopy

On 6/3/25 5:06 PM, Bui Quang Minh wrote:

In virtio-net, we have not yet supported multi-buffer XDP packet in zerocopy mode when there is a binding XDP program. However, in that case, when receiving multi-buffer XDP packet, we skip the XDP program and return XDP_PASS. As a result, the packet is passed to normal network stack which is an incorrect behavior.

Why? AFAICS the multi-buffer mode depends on features negotiation, which is not controlled by the VM user.

Let's suppose the user wants to attach an XDP program to do some per packet stats accounting. That suddenly would cause drop packets depending on conditions not controlled by the (guest) user. It looks wrong to me.

XDP_ABORTED looks like a better choice.

/P