Re: [PATCH v2 3/10] KVM: MMU: fix direct sp's access corruptted

Avi Kivity
2010-06-29T09:13:36Z

On 06/29/2010 12:04 PM, Xiao Guangrong wrote:
>
>> Simply replace (*spte& SPTE_NO_DIRTY) with a condition that checks
>> whether sp->access is consistent with gw->pt(e)_access.
>>
>>
> If the guest mapping is writable and it !dirty, we mark SPTE_NO_DIRTY flag in
> the spte, when the next #PF occurs, we just need check this flag and see whether
> gpte's D bit is set, if it's true, we zap this spte and map to the correct sp.
>

My point is, SPTE_NO_DIRTY is equivalent to an sp->role.access check
(the access check is a bit slower, but that shouldn't matter).

>> Can you write a test case for qemu-kvm.git/kvm/test that demonstrates
>> the problem and the fix? It will help ensure we don't regress in this
>> area.
>>
>>
> OK, but allow me do it later :-)
>
>

Sure, but please do it soon.

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