Hi, CentOS 7.3 was released yesterday and a newer version of qemu-kvm-ev was shipped as part of this release if you have the CentOS Virtualization SIG repositories enabled. If you're using RDO >= Newton, you will have this repository enabled. It was not yet enforced in the Mitaka release so you might or might not have it, depending on your deployment. Older releases of OpenStack may also be affected but they are not proactively tested anymore due to EOL. There is currently a known issue when using the following configuration in nova for compute: == virt_type=qemu cpu_mode=host-model == This combination will yield in failed attempts at creating instances and you will see errors like these in nova-compute.log [1] or the libvirt logs [2]. The problem boils down to libvirt trying to pass a cpu extension that is unknown to qemu: == qemu-kvm: CPU feature arat not found == There is a bugzilla [3] for this issue but in the meantime users are encouraged to work around the issue by setting "cpu_mode=none" if they are using the qemu (not KVM) hypervisor. Please note that Nova defaults the 'cpu_mode' parameter to 'host-model' [4] if 'cpu_mode' is not explicitely configured and 'virt_type' is 'qemu' so if you're running into this issue, you will need to explicitely configure it. [1]: http://logs.openstack.org/76/409476/4/check/gate-puppet-openstack-integra... [2]: http://logs.openstack.org/76/409476/4/check/gate-puppet-openstack-integra... [3]: https://bugzilla.redhat.com/show_bug.cgi?id=1371617 [4]: http://git.openstack.org/cgit/openstack/nova/tree/nova/virt/libvirt/drive... David Moreau Simard Senior Software Engineer | Openstack RDO dmsimard = [irc, github, twitter]