Re: [PATCH v9 4/6] KVM: x86: Introduce untag_addr() in kvm_x86_ops

[Binbin Wu]

On 6/29/2023 11:16 PM, Sean Christopherson wrote:
> > And for LAM, X86EMUL_F_IMPLICIT will not be used because in the implicit
> > access to memory management registers or descriptors,
> > the linear base addresses still need to be canonical and no hooks will be
> > added to untag the addresses in these pathes.
> > So I probably will remove the check for X86EMUL_F_IMPLICIT here.
> No, please keep it, e.g. so that changes in the emulator don't lead to breakage,
> and to document that they are exempt.
>
> If you want, you could do WARN_ON_ONCE() for the IMPLICIT case, but I don't know
> that that's worthwhile, e.g. nothing will go wrong if KVM tries to untag an
> implicit access, and deliberately avoiding the call make make it annoying to
> consolidate code in the future.
Right.
Have a second thought, X86EMUL_F_IMPLICIT should be kept in case SVM has 
a different implementation and needs to do untag for IMPLICIT cases.