[ovs-discuss] Vhost Ports on OVS DPDK Bridge do not work when using virsh xml file

Wittling, Mark (CCI-Atlanta) Mark.Wittling at cox.com
Wed Sep 9 15:50:00 UTC 2020

I have an issue that when I add a vhost port to a an OVS bridge (and it doesn’t matter if it is vhostuser or vhostuserclient), the port adds okay, but the link state remains down and the port serves no traffic. I have a DPDK NIC attached to this same bridge, and it appears to work.

The more interesting thing, is that the vhost ports seem to work if I crank the VM up with a bash script that runs qemu-kvm and all the options along with it.

The OVS version is 2.11.1, compiled with DPDK version 18.11.8. The kernel version is 3.10.0-1127.13.1.el7.x86_64.

  *   I looked into updating to a 4.x kernel, but I am running CentOS7 and the CentOS folks told me that they backport, and that updating the kernel would cause more problems than I could ever possibly solve.

Originally, I suspected vhostuserclient to be the issue, and backed down from that and went to vhostuser (where the OVS is the server and QEMU is the client). Same problem.

The XML I am using is:
<interface type=’vhostuser’>
<mac address=’52:54:00:d1:ba:7a’/>
<source type=’unix’ path=’/var/run/openvswitch/dpdkvhost1’ mode=’client’/>
<model type=’virtio’/>
<address type=’pci’ domain=’0x0000’ bus=’0x00’ slot=’0x0b’ function=’0x0’/>

Pretty standard config. Now one thing I will mention, is that I have to put 777 on that socket in the /var/run/openvswitch directory for the VM to start up with virsh-manager GUI. The reason for this is that qemu cannot write to a socket that is created by openvswitch using the openvswitch user group. But I don’t think that matters at all.

Does anyone have a clue on why this doesn’t work? Or how to get this port link state back up and serving traffic?


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