Re: [PATCH] KVM: TDX: Set SIGNIFCANT_INDEX flag for supported CPUIDs

[Edgecombe, Rick P]

On Tue, 2026-02-24 at 12:42 -0800, Sean Christopherson wrote:
> > I'm still not clear on the impact of this one, but assuming it's not too
> > serious, could we discuss the WIP CPUID bit TDX arch stuff in PUCK before
> > doing the change?
> 
> Sure, I don't see a rush on the patch.

Should we try for tomorrow or next week?

> 
> > We were initially focusing on the problem of CPUID bits that affect host
> > state, but then recently were discussing how many other categories of
> > potential problems we should worry about at this point. So it would be good
> > to understand the impact here.
> > 
> > If this warn is a trend towards doubling back on the initial decision to
> > expose the CPUID interface to userspace,
> 
> Maybe I'm missing something, but I think you're reading into the WARN waaaay
> too much.  I suggested it purely as a paranoid guard against the TDX Module
> doing something bizarre and/or the kernel fat-fingering a CPUID function. 
> I.e. there's no ulterior motive here, unless maybe Changyuan is planning world
> domination or something. :-D

Heh, well we are already seeing new CPUID bits that cause problems. Not
suspecting any secret motives, but more trying to glean something on your
thinking. Will be easier to discuss the topic.

> 
> > which I think is still doable and worth considering as an alternative, then
> > this also affects how we would want the TDX module changes to work.