Re: [PATCH 1/3] cpu/SMT: create and export cpu_smt_possible()

[Jim Mattson]

On Mon, Sep 16, 2019 at 9:23 AM Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> wrote:
>
> KVM needs to know if SMT is theoretically possible, this means it is
> supported and not forcefully disabled ('nosmt=force'). Create and
> export cpu_smt_possible() answering this question.

It seems to me that KVM really just wants to know if the scheduler can
be trusted to avoid violating the invariant expressed by the Hyper-V
enlightenment, NoNonArchitecturalCoreSharing. It is possible to do
that even when SMT is enabled, if the scheduler is core-aware.
Wouldn't it be better to implement a scheduler API that told you
exactly what you wanted to know, rather than trying to infer the
answer from various breadcrumbs?