Re: KVM guest crashes

[Avi Kivity <avi@redhat.com>]

Alexander Graf wrote:
> Hi list,
>
> recently I've been hitting some KVM bugs others seem to have reported as
> well, including
>
> - CIFS timeouts
> - Stuck ?? errors
> - Random segmentation faults in the guest
>
> so I figured, I'll put together a stress test that can be used to
> reproduce these issues. This is done by using a CIFS mount on the host
> and unpacking data from that mount to the mount. I have been able to
> bring kvm down to its knees a lot just by doing this.
> Simply run the test in an endless-loop. FWIW enabling NPT helps
> triggering the issue.
>
>   

Are the problems specific to AMD?  What does "helps triggering" mean - 
does it happen with NPT disabled?

> The guest kernels included here are openSUSE 11.0 (2.6.25) and 11.1
> (2.6.27) kernels.
>
> Find the tests here: http://alex.csgraf.de/kvm-tests.tar.bz2
> And some logs here (NPT enabled): http://alex.csgraf.de/kvm-logs.tar.bz2
>
> I'm somewhat lost on the reason for these failures, so if you do have
> some time on your hands, please give me a hand debugging this! If I'd
> had to guess, I'd say it's either an APIC issue and/or guest memory
> corruption.
>   

I'd guess memory corruption.

Does running a uniprocessor guest help?  What about a uniprocessor guest 
pinned to one host core?

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.