Re: [PATCH v3 7/9] KVM: nSVM: implement nested_svm_load_cr3() and use it for host->guest switch

Paolo Bonzini
2020-07-10T12:08:43Z

On 10/07/20 13:40, Vitaly Kuznetsov wrote:
> Hm, it seems I missed svm_set_nested_state() path
> completely. Surprisingly, state_test didn't fail)
>
> I'm struggling a bit to understand why we don't have kvm_set_cr3() on
> svm_set_nested_state() path: enter_svm_guest_mode() does it through
> nested_prepare_vmcb_save() but it is skipped in svm_set_nested_state().
> Don't we need it at least for !npt_enabled case?

In svm_set_nested_state you'll have CR3 already set to the right value.
On the source, KVM_GET_SREGS returns the vmcb12's CR3 and it is already
restored with KVM_SET_SREGS on the destination before set_nested_state.

So, only the nested_cr3 has to be set.

Paolo

> We'll have to extract
> nested_cr3 from nested_vmcb then.