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Bug 530389

Summary: allow userspace to adjust kvmclock offset
Product: [Fedora] Fedora Reporter: Glauber Costa <gcosta>
Component: kernelAssignee: Justin M. Forbes <jforbes>
Status: CLOSED ERRATA QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: high    
Version: 13CC: dougsland, gansalmon, itamar, jforbes, kernel-maint, markmc, virt-maint
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 554504 (view as bug list) Environment:
Last Closed: 2010-09-03 10:07:55 EDT Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Bug Depends On:    
Bug Blocks: 498969, 554504    
Attachments:
Description Flags
Patch for it. none

Description Glauber Costa 2009-10-22 11:46:13 EDT
Description of problem:
In order get migration of kvm guests working on remote and unsynchronized hosts, we need two new ioctls that will allow us to adjust pvclock value.

Those patches are in upstream kvm kernel, and I will provide a backport shortly.
Comment 1 Glauber Costa 2009-10-23 07:07:39 EDT
scratch build at : http://koji.fedoraproject.org/koji/taskinfo?taskID=1763328
Comment 2 Glauber Costa 2009-10-23 07:10:51 EDT
Created attachment 365834 [details]
Patch for it.
Comment 3 Mark McLoughlin 2009-10-29 09:07:26 EDT
Okay, it's queued up in Avi's tree here:

  http://git.kernel.org/?p=linux/kernel/git/avi/kvm.git;a=commitdiff;h=a6048dd2da
  http://git.kernel.org/?p=linux/kernel/git/avi/kvm.git;a=commitdiff;h=958b0c5497

which means it should be in 2.6.33

The qemu-kvm side is here:

  http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commitdiff;h=e4d6d49061
  http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commitdiff;h=11ed4b344c
  http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commitdiff;h=79529cd015

which should be in qemu-kvm-0.12.0

Glauber: are you proposing to pull the new ioctl for 2.6.31 in Fedora 12?

What are the symptoms of the bug? i.e. how bad is it? could it wait until Fedora 13?
Comment 4 Glauber Costa 2009-10-29 09:15:33 EDT
(In reply to comment #3)
> Okay, it's queued up in Avi's tree here:
> 
>  
> http://git.kernel.org/?p=linux/kernel/git/avi/kvm.git;a=commitdiff;h=a6048dd2da
>  
> http://git.kernel.org/?p=linux/kernel/git/avi/kvm.git;a=commitdiff;h=958b0c5497
> 
> which means it should be in 2.6.33
> 
> The qemu-kvm side is here:
> 
>   http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commitdiff;h=e4d6d49061
>   http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commitdiff;h=11ed4b344c
>   http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commitdiff;h=79529cd015
> 
> which should be in qemu-kvm-0.12.0
> 
> Glauber: are you proposing to pull the new ioctl for 2.6.31 in Fedora 12?

I guess we could. The patch is there, and is already a backport to F12 tree, should apply just fine. So it's really up to the kernel maintainer.

I can backport the userspace part if we get the kernel part working.

> What are the symptoms of the bug? i.e. how bad is it? could it wait until
> Fedora 13?  

Imagine two hosts A and B
A has a smaller monotonic clock than B (say, B was booted first)

If you migrate A -> B, you get a time jump.
If you migrate B -> A, you get backwards timing, and machine hangs
Comment 5 Mark McLoughlin 2009-10-29 10:03:24 EDT
(In reply to comment #4)
> (In reply to comment #3)
> > Okay, it's queued up in Avi's tree here:
> > 
> >  
> > http://git.kernel.org/?p=linux/kernel/git/avi/kvm.git;a=commitdiff;h=a6048dd2da
> >  
> > http://git.kernel.org/?p=linux/kernel/git/avi/kvm.git;a=commitdiff;h=958b0c5497
> > 
> > which means it should be in 2.6.33
...
> > Glauber: are you proposing to pull the new ioctl for 2.6.31 in Fedora 12?
> 
> I guess we could. The patch is there, and is already a backport to F12 tree,
> should apply just fine.

Ah, good - the patch you attached is the combination of both those commits.

Justin, it sounds important enough to get this queued up for a post-GA update.
Comment 6 Bug Zapper 2010-03-15 08:58:05 EDT
This bug appears to have been reported against 'rawhide' during the Fedora 13 development cycle.
Changing version to '13'.

More information and reason for this action is here:
http://fedoraproject.org/wiki/BugZappers/HouseKeeping
Comment 7 Chuck Ebbert 2010-09-03 10:07:55 EDT
F13 now has kernel 2.6.34