Re: kvm-unit-test failures

[Paolo Bonzini <pbonzini@redhat.com>]

Il 04/09/2014 14:24, Wanpeng Li ha scritto:
> On Thu, Sep 04, 2014 at 01:33:10PM +0200, Paolo Bonzini wrote:
>> Il 04/09/2014 11:53, Paolo Bonzini ha scritto:
>>> Il 03/09/2014 20:25, Chris J Arges ha scritto:
>>>> <snip>
>>>>> I'm not sure about the reason for the warp, but indeed the offset and
>>>>> uptime match (I'll check them against the trace tomorrow) so it's "just"
>>>>> that the VM's TSC base is not taken into account correctly.
>>>>>
>>>>> Can you gather another trace with the problematic patch reverted?
>>>>>
>>>>> Paolo
>>>>>
>>>>
>>>> Here is the third trace running with 0d3da0d2 reverted from the latest
>>>> kvm queue branch 11cc9ea3:
>>>>
>>>> http://people.canonical.com/~arges/kvm/trace-3.dat.xz
>>>
>>> Thanks!  And---yay!---I reproduced it on another machine.
>>
>> And my bisection landed on the merge of the timer branch (commit
>> e7fda6c4c3c1a7d6996dd75fd84670fa0b5d448f).  Here is the log:
>>
>> $ git bisect bad origin/master
>> $ git bisect good v3.16
>> $ git bisect good kvm-3.17-1 # 42cbc04fd3b5e3f9b011bf9fa3ce0b3d1e10b58b
>>
>> good    [ 6929.863545] loaded kvm module (v3.17-rc1-158-g451fd72219dd)
>> bad     [ 6971.932790] loaded kvm module (for-linus)
>> bad     [ 7216.073128] loaded kvm module (v3.16-6426-gae045e245542)
>> good    [ 7286.198948] loaded kvm module (v3.16-3283-g53ee983378ff)
>> good    [ 7350.534060] loaded kvm module (v3.16-rc7-1668-gaef4f5b6db65)
>> good    [ 7439.037038] loaded kvm module (v3.16-4006-g91c2ff7708d4)
>> good    [ 7481.188637] loaded kvm module (v3.16-rc6-450-g7ba3c21c17d0)
>> bad     [ 7535.292730] loaded kvm module (v3.16-4635-ge7fda6c4c3c1)
>> good    [ 7589.722691] loaded kvm module (v3.16-rc5-110-g9b0fd802e8c0)
>> good    [ 7630.286418] loaded kvm module (v3.16-4467-ged5c41d30ef2)
>> good    [ 7712.470986] loaded kvm module (v3.16-rc1-35-g885d078bfe92)
>> good    [ 7763.443626] loaded kvm module (v3.16-rc1-381-g1b0733837a9b)
>> good    [ 7825.497414] loaded kvm module (v3.16-rc5-116-g7806f60e1d20)
>> good    [ 7893.174056] loaded kvm module (v3.16-rc1-384-gc6f1224573c3)
>>
>> This means that:
>>
>> - Tomasz's patch (commit 0d3da0d26e3c3515997c99451ce3b0ad1a69a36c) is
>> fine, it just enables the (wrong) master clock more often
>>
>> - the failure is within that branch.
>>
>> I then cherry-picked Tomasz's patch during a new bisection, and landed
>> on one of my original suspects:
>>
>> commit cbcf2dd3b3d4d990610259e8d878fc8dc1f17d80
>> Author: Thomas Gleixner <tglx@linutronix.de>
>> Date:   Wed Jul 16 21:04:54 2014 +0000
>>
>>    x86: kvm: Make kvm_get_time_and_clockread() nanoseconds based
>>
>>    Convert the relevant base data right away to nanoseconds instead of
>>    doing the conversion on every readout. Reduces text size by 160
>>    bytes.
>>
>>    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>>    Cc: Gleb Natapov <gleb@kernel.org>
>>    Cc: kvm@vger.kernel.org
>>    Acked-by: Paolo Bonzini <pbonzini@redhat.com>
>>    Signed-off-by: John Stultz <john.stultz@linaro.org>
>>
> 
> Yes, I also look into this bad commit recently which lead to guest hang
> after live migration or after local save/restore. 

Thanks for the report!

Wanpeng, can you test and/or review the patch I just posted ("[PATCH]
KVM: x86: fix kvmclock breakage from timers branch merge")?

Paolo