What were you trying to do that didn't work?

A VM with DPDK port is live migrated. On completion, qemu checks that GUEST_ANNOUNCE is supported. If so, then qemu won't send RARP to announce itself. Instead, it's expected that virtio will do. It does - sending GARPs and/or NAs; but not RARPs.

What is the impact of this issue to you?

The problem is twofold:

• SDN may expect RARP sent on destination port activation. For example, OVN controller uses the packet to detect the completion of migration, to allow traffic from/to the port. Since RARP is never received - the port is never unblocked.
• Ports without IP addresses won't send any packets at all, neither GARP nor NA.

Please provide the package NVR for which the bug is seen:

How reproducible is this bug?:

Always.

Steps to reproduce

1. Start a VM with DPDK port and kernel that supports GUEST_ANNOUNCE.
2. Live migrate the VM.
3. Observe that RARP packet is not sent from the port after migration completed.

Expected results

RARP is sent, in addition to GARP / NA that virtio may have sent.

Actual results

No RARP.

Other info:

The upstream bug for the same: https://gitlab.com/qemu-project/qemu/-/issues/2745