Re: qemu-kvm-1.1.0 crashing with kernel 3.5.0-rc6

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-07-26 12:49, Jan Kiszka wrote:
> On 2012-07-26 12:45, Avi Kivity wrote:
>> On 07/26/2012 01:29 PM, Jan Kiszka wrote:
>>
>>>> It looks like general memory corruption.  Is this repeatable?  What's
>>>> the guest uptime when it happens (i.e. is it immediate?)
>>>>
>>>> Jan, why are we calling cpu_set_apic_tpr() with kvm_irqchip_in_kernel?
>>>
>>> To sync the userspace state with what the kernel maintains. Will end up
>>> in kvm_apic_set_tpr which does precisely this. We always did, just the
>>> QOM modeling is new.
>>
>> We should move it to the general register synchronization code, there is
>> no reason to do this every exit (though the cost is likely minimal).
> 
> The cost is, well, was close to nothing. But I'm not sure about that QOM
> type casting magic (and also it's locking requirements, long-term).
> However, if that is a problem, it's likely a much bigger one anyway.

But, independent of this, we can likely move the whole kvm_arch_post_run
out of the exit path for kvm_irqchip_in_kernel() == true. The price is
that we create more deviation between both, but that should be
controllable. I will play with a patch.

Jan

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