Re: [PATCH v5 03/15] KVM: SVM: Disable SEV/SEV-ES if NPT is disabled

Paolo Bonzini
2021-04-22T17:10:12Z

On 22/04/21 18:15, Sean Christopherson wrote:
>> Support for 5-level page tables on NPT is not hard to fix and could be
>> tested by patching QEMU. However, the !NPT case would also have to be fixed
>> by extending the PDP and PML4 stacking trick to a PML5.
>
> Isn't that backwards? It's the nested NPT case that requires the stacking trick.
> When !NPT is disabled in L0 KVM, 32-bit guests are run with PAE paging. Maybe
> I'm misunderstanding what you're suggesting.

Yes, you're right. NPT is easy but we would have to guess what the spec
would say about MAXPHYADDR, while nNPT would require the stacking of a
PML5. Either way, blocking KVM is the easiest thing todo.

Paolo