Re: Oops for sale

[Avi Kivity <avi@qumranet.com>]

Gerd Hoffmann wrote:
> 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.