[rdo-list] Known issue with CentOS 7.3 and qemu-kvm(-ev) 2.6.0

David Moreau Simard dms at redhat.com
Wed Dec 14 15:10:36 UTC 2016

I'll cross-link the thread from openstack-dev/openstack-operators as
there are some interesting insight there as well:

openstack-dev: http://lists.openstack.org/pipermail/openstack-dev/2016-December/108884.html

David Moreau Simard
Senior Software Engineer | Openstack RDO

dmsimard = [irc, github, twitter]

On Tue, Dec 13, 2016 at 6:16 PM, David Moreau Simard <dms at redhat.com> wrote:
> 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-integration-4-scenario003-tempest-centos-7/8881991/logs/nova/nova-compute.txt.gz#_2016-12-13_16_39_50_832
> [2]: http://logs.openstack.org/76/409476/4/check/gate-puppet-openstack-integration-4-scenario003-tempest-centos-7/8881991/logs/libvirt/qemu/instance-00000001.txt.gz
> [3]: https://bugzilla.redhat.com/show_bug.cgi?id=1371617
> [4]: http://git.openstack.org/cgit/openstack/nova/tree/nova/virt/libvirt/driver.py?id=146b27f22327f8d60c1017c22ccf18d0e16f1eb7#n3411
> David Moreau Simard
> Senior Software Engineer | Openstack RDO
> dmsimard = [irc, github, twitter]

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