Re: [PATCH] KVM: x86: synthesize TSA CPUID bits via SCATTERED_F()

[Borislav Petkov]

On Wed, Feb 11, 2026 at 07:54:30AM -0800, Sean Christopherson wrote:
> Those problems are _entirely_ limited to the fact that the kernel's feature tracking
> isn't 100% comprehensive.

Thus the rewrite. :)

> If the kernel tracks both raw CPUID *and* kernel caps, then KVM can use the
> table without having to (re)do CPUID when configuring KVM's feature set.  But
> KVM would still need to have processing for SYNTHESIZED_F, PASSTHROUGH_F, and F,
> to derive the correct state from the raw+kernel tables.

That's what I meant - the macros and the confusion which one to use would go
away.

> Because from my perspective, centralizing *everything* is all pain, no gain.  It
> would bleed KVM details into the broader kernel, unnecessarily limit KVM's ability
> to change how KVM emulates/virtualizes features, and require querying a lookaside
> table to understand KVM's rules/handling.  No thanks.

The point is not to limit KVM's ability but *augment* the internal
representation so that it *accomodates* KVM fully. But ok, your call.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette