Re: Oops for sale

Avi Kivity
2008-06-11T03:04:43Z

> Avi Kivity wrote:
>
>> The unshadow-on-userspace-access heuristic is broken. Since it is also
>> bad for Xenner, try removing the following lines:
>>
>> spte |= PT_WRITABLE_MASK;
>>
>
> Well, that line should better not be removed. I get a hang otherwise,
> guess due to running into a page-fault loop ...
>
>

Sorry, that was unintended.

>> if (user_fault) {
>> mmu_unshadow(vcpu->kvm, gfn);
>> goto unshadowed;
>> }
>>
>
> Deactivating those four lines fixed it.
>
>

Yeah, I'll drop them for kvm.git. This never triggered since OSes are
conscientious about scrubbing page tables, and when they do that the
flood detector unshadows the pages.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.