Bug 858216 - libvirt_cpu_mode defaults to host-model for kvm and qemu
Summary: libvirt_cpu_mode defaults to host-model for kvm and qemu
Alias: None
Product: Fedora
Classification: Fedora
Component: openstack-nova
Version: 18
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Xavier Queralt
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2012-09-18 10:46 UTC by Eoghan Glynn
Modified: 2014-06-18 07:00 UTC (History)
18 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2014-02-05 12:12:46 UTC

Attachments (Terms of Use)

Description Eoghan Glynn 2012-09-18 10:46:43 UTC
Description of problem:

When an instance is spun up on a VM running openstack (as opposed to bare metal), we see the following error in the nova-compute logs:

  "libvirtError: unsupported configuration: CPU specification not supported by hypervisor"


Add the line:


to /etc/nova/nova.conf

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. Boot an instance

Actual results:

Instance status goes to error.

Expected results:

Instance status goes to error.

Comment 2 Daniel Berrangé 2012-09-24 11:38:19 UTC
Jiri, do you have any knowledge of problems with setting CPU models when running a QEMU instance inside a KVM guest. The scenario is that OpenStack sets  mode="host-model" for all guests by default, this works fine running guest on bare metal, but fails when running inside a guest.

Comment 3 Jiri Denemark 2012-09-25 07:02:06 UTC
Ah, I guess it fails because libvirt is not able to match host CPU with any CPU model it knows about. Can you confirm that by running 'virsh capabilities' and checking the <cpu> element there? If that's the case, the host is likely masking some CPU features that are comonly present in all CPU models. A feature called "sep" is known to be missing in guests running on RHEL hosts, for example.

Comment 4 Fedora Admin XMLRPC Client 2013-12-16 16:21:03 UTC
This package has changed ownership in the Fedora Package Database.  Reassigning to the new owner of this component.

Comment 5 Fedora End Of Life 2013-12-21 08:53:27 UTC
This message is a reminder that Fedora 18 is nearing its end of life.
Approximately 4 (four) weeks from now Fedora will stop maintaining
and issuing updates for Fedora 18. It is Fedora's policy to close all
bug reports from releases that are no longer maintained. At that time
this bug will be closed as WONTFIX if it remains open with a Fedora 
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Comment 6 Fedora End Of Life 2014-02-05 12:12:55 UTC
Fedora 18 changed to end-of-life (EOL) status on 2014-01-14. Fedora 18 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

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