Re: [PATCH] KVM: SVM: fix random segfaults with NPT enabled

Avi Kivity
2008-08-27T13:53:28Z

Avi Kivity wrote:
> Joerg Rodel wrote:
>> From: Joerg Roedel <joerg.roedel@amd.com>
>>
>> This patch introduces a guest TLB flush on every NPF exit in KVM.
>> This fixes
>> random segfaults and #UD exceptions in the guest seen under some
>> workloads
>> (e.g. long running compile workloads or tbench). A kernbench run with
>> and
>> without that fix showed that it has a slowdown lower than 0.5%
>>
>>
>
> hm. tbench doesn't allocate memory, so there shouldn't be any npt
> faults. I don't see how this can make a difference.
>
> It can only change something if X is started and we're tracking writes
> to the framebuffer. Is this the case?
>

I fixed a missing flush in this area. Does it help? (I doubt it). Can
you post instructions on how to reproduce?

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