Hi Konstantin yes, we have found this kind of issue in this upstream So here is a fix for this problem in kernel https://lore.kernel.org/kvm/caclfguuyny6-1cyabsgs+qtdzo+mkp3o09t_gt-bmm4jgdp...@mail.gmail.com/T/ vdpa: support set mac address from vdpa tool
This tool allows the user to change the MAC address before QEMU loads. The user should ensure that the VDPA device's MAC address matches the MAC address in the QEMU command line. On the QEMU side, we plan to add a new parameter to check the MAC address. If the MAC address in the QEMU command line does not match the device's MAC address, the system will fail to boot. https://patchew.org/QEMU/20241109063241.1039433-1-l...@redhat.com/ but this patch is not merged in upstream yet, I will rebase and send it to upstream again Thanks Cindy On Thu, Mar 20, 2025 at 8:59 AM Jason Wang <jasow...@redhat.com> wrote: > > Adding Cindy and Eugenio > > On Thu, Mar 20, 2025 at 12:34 AM Konstantin Shkolnyy <k...@linux.ibm.com> > wrote: > > > > I’m observing a problem while testing VDPA with Nvidia ConnectX-6 (mlx5) > > on s390. > > > > Upon start, virtio_net_device_realize() tries to set a new MAC address > > by VHOST_VDPA_SET_CONFIG which doesn’t do anything. > > > > Later, the VM gets started and learns about the old address from > > virtio_net_get_config() which returns whatever VHOST_VDPA_GET_CONFIG > > returns, unless it's "6 zero bytes", in which case it instead returns > > the desired new address (and the problem is avoided). > > > > Then QEMU again tries to set the new address from vhost_net_start(), now > > by calling vhost_vdpa_net_load_cmd(...,VIRTIO_NET_CTRL_MAC, > > VIRTIO_NET_CTRL_MAC_ADDR_SET, ...). This time the new address is > > successfully programmed into the NIC, but the VM doesn't know about it. > > Have you enabled shadow virtqueue? If yes, does it work if you don't do that? > > > > > As the result, the VM now sends packets with a source address on which > > the NIC doesn’t listen. > > > > Upon reading this forum, I see that VHOST_VDPA_SET_CONFIG is > > “deprecated”, and so VIRTIO_NET_CTRL_MAC_ADDR_SET must be the right > > method, but it’s apparently called too late. > > VHOST_VDPA_SET_CONFIG requires the vDPA parent support which is not > necessarily there. > VIRTIO_NET_CTRL_MAC_ADDR_SET requires the shadow virtqueue as well as > the CTRL_MAC_ADDR support. > > Neither of them seems robust. > > > Or maybe > > virtio_net_get_config() needs to always return the desired new address > > and not the old one from VHOST_VDPA_GET_CONFIG? > > > > I’m looking for an opinion/direction from someone who knows this code. > > > > As it is, the only VDPA scenario that's working for me is: > > 1) Avoid specifying the MAC address in the "vdpa dev add" command (which > > will create the "6 zero bytes" condition on the first launch). > > 2) Keep using the same MAC address for every subsequent VM launch on the > > same NIC "virtual function" (so that the old and new addresses are the > > same). > > This is the way we currently use it. Is there any limitation of this? > > Thanks > > > >
