From mboxrd@z Thu Jan  1 00:00:00 1970
From: Zachary Amsden <zamsden@redhat.com>
Subject: Re: 2.6.35-rc1 regression with pvclock and smp guests
Date: Thu, 07 Oct 2010 16:47:11 -1000
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Cc: kvm@vger.kernel.org, Marcelo Tosatti <mtosatti@redhat.com>,
	Michael Tokarev <mjt@tls.msk.ru>, Avi Kivity <avi@redhat.com>,
	Glauber Costa <glommer@redhat.com>,
	Andre Przywara <andre.przywara@amd.com>
To: Arjan Koers <0h61vkll2ly8@xutrox.com>
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On 10/07/2010 02:12 PM, Arjan Koers wrote:
> On 2010-10-03 01:42, Zachary Amsden wrote:
> ...
>    
>> Umm...  do you guys have this commit?  This is supposed to address the
>> issue where the guest keeps resetting the TSC.  A guest which does that
>> will break kvmclock.  It only happens on SMP, and it's much worse on AMD
>> CPUs...
>>
>> sound like your scenario.
>>
>> commit bd59fc8ff95126f27b7a0df1b6cc602aa428812d
>> Author: Zachary Amsden<zamsden@redhat.com>
>> Date:   Thu Aug 19 22:07:26 2010 -1000
>>      
>
> This commit fixes the problem:
>
> commit aad07c4f92bae2edaa42bcef84c2afdd0d082458
> Author: Zachary Amsden<zamsden@redhat.com>
> Date:   Thu Aug 19 22:07:19 2010 -1000
>
>      KVM: x86: Move TSC reset out of vmcb_init
>
>      The VMCB is reset whenever we receive a startup IPI, so Linux is setting
>      TSC back to zero happens very late in the boot process and destabilizing
>      the TSC.  Instead, just set TSC to zero once at VCPU creation time.
>
>      Why the separate patch?  So git-bisect is your friend.
>    

Okay, apparently I need to go poke around 2.6.35 and see what patches 
made it there and what patches didn't.