Bug 710275

Summary:	KVM guest will not start when specifying Penryn processor in virt-manager on RHEL6.1 server with Intel Xeon E7440 processors.
Product:	Red Hat Enterprise Linux 6	Reporter:	Kevin Toyama <ktoyama>
Component:	libvirt	Assignee:	Michal Privoznik <mprivozn>
Status:	CLOSED NOTABUG	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	medium	Docs Contact:
Priority:	low
Version:	6.1	CC:	dallan, jdenemar, rfreire
Target Milestone:	rc	Keywords:	Reopened
Target Release:	6.2
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2012-01-05 18:14:35 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:

Description Kevin Toyama 2011-06-02 21:24:18 UTC

Description of problem: Customer has HP BL460c G5 blades with Intel Xeon E7440 Dunnington (Penryn) processors.  Customer creates a KVM guest using virt-manager and after building would like to change the processor to Penryn.  Guest will not boot with following error resulting:

libvirtError: internal error guest CPU is not compatible with host CPU

Click "copy host cpu configuration" and instead of showing the Penryn processor it will show "Pentium III".


Version-Release number of selected component (if applicable):
virt-manager-0.8.6-4.el6.noarch

How reproducible:
Always,

Steps to Reproduce:
1. on BL460c G5 with E7440 processors, create KVM guest using default options for CPU.
2. build guest and see it properly boot.
3. Stop the guest and edit the configuration through virt-manager and see choose Penryn processor in CPU configuration.  Guest will not boot with error about incompatible CPU.
4. Click on "Copy Host CPU configuration" and it will select the Pentium III which is incorrect.

  
Actual results:
libvirtError: internal error guest CPU is not compatible with host CPU

Click "copy host cpu configuration" and instead of showing the Penryn processor it will show "Pentium III".



Expected results:
Either specifying "Penryn" or using the copy Host CPU configuration button will result in Penryn and a successful KVM guest boot.

Additional info:

Comment 2 Cole Robinson 2011-06-10 22:48:03 UTC

I think everything is working correctly here, it's just how libvirt notates what CPU the host is using. It has some internal definitions, and if your host does not expose all the flag values it has listed for 'Penryn' it finds the next CPU that it fully matches (in this case 'Pentium III') and then lists each additional flag individually. This can be seen in the <host> section of 'virsh capabilities'

Does 'copy host configuration' should be exposing every host cpu flag to the guest, even if it isn't using the expected CPU name. So I don't think there's a bug here.

Comment 3 Cole Robinson 2011-06-10 22:48:35 UTC

Closing as NOTABUG, please reopen if I've missed something.

Comment 5 Cole Robinson 2011-06-14 19:16:52 UTC

Reassigning to libvirt, maybe jdenemar can chime in.

Comment 12 Dave Allan 2012-01-05 18:14:35 UTC

We can't get further access to the systems exhibiting the behavior, so I have to close this as insufficent data.  Please don't hesitate to reopen if the systems become available.

Comment 13 Michal Privoznik 2012-02-03 12:37:40 UTC

Kevin and others.

I've helped a guy with the very same problem as here. And it turned out, he has 'nx' flag disabled (No eXecution) in BIOS. Re-enabling it made the problem go away.

Comment 14 Rodrigo A B Freire 2012-02-03 12:40:51 UTC

Changed the closed reason to NOTABUG