Re: [PATCH 3/4] Nested SVM: Implement INVLPGA v2

[Avi Kivity <avi@redhat.com>]

Alexander Graf wrote:
>>>> kvm_mmu_invlpg is cheap, better just invalidate the entry. If hyper-v
>>>> uses invlpga to invalidate TLB entries which it has updated pte's in
>>>> memory for, and you skip the invalidation now and somehow later use an
>>>> unsync spte, you're toast.
>>>>
>>>
>>> But won't the guest entry cause a resync?
>>
>> If its a cr3/cr4 exit, yes.
>
> Well it has to be. Either we're switching from one NPT to the other 
> (todo) or do a normal cr3+cr4 switch.
>
> So I guess we can optimize here. Is it worth it?
>

I think so.  We also need to make sure the entry causes a resync, even 
if cr3 doesn't change.

Oh, exit needs to force a resync as well, in case the guest foolishly 
let its guest touch its page tables and issue invlpga asid=0.

-- 
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