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