Re: [PATCH RFC] KVM: nSVM: Fix L1 state corruption upon return from SMM

[Sean Christopherson]

On Wed, Jun 23, 2021, Sean Christopherson wrote:
> And I believe this hackery is necessary only because nested_svm_vmexit() isn't
> following the architcture in the first place.  I.e. using vmcb01 to restore
> host state is flat out wrong.

Ah, that's not true, using vmcb01 is allowed by "may store some or all host state
in hidden on-chip memory".

>From a performance perspective, I do like the SMI/RSM shenanigans.  I'm not
totally opposed to the trickery since I think it will break a guest if and only
if the L1 guest is also violating the APM.  And we're not fudging the spec thaat
much :-)