Recent change in tripleo  configure nova rx_queue_size tx_queue_size config
It seem that this config option breaks booting vm with SR-IOV. See 
The issues is because of this code  which configure virtio queue size if the
in the interface xml the driver is vhost or None.
In case of SR-IOV the driver is also None and that why we get the error.
A quick fix will be adding driver=vfio to 
I just wonder if there are other interface in the libvirt xml which this can
have the same issue.
 - http://paste.openstack.org/show/728666/
 - https://review.openstack.org/#/c/595592/
OpenStack Development Mailing List (not for usage questions)