Re: [PATCH] x86/cpufeatures: Correct LKGS feature flag description

From: Borislav Petkov

Date: Wed Oct 15 2025 - 11:49:30 EST


On Wed, Oct 15, 2025 at 08:44:55AM -0700, H. Peter Anvin wrote:
> >> Except that that is also wrong, because that's not all of what the instruction does. "Load user space GS" is really what it does, despite the initiate historical naming.
> >>
> >
> >Do you mean the load of GS attributes by LKGS is still missing?
>
> Yes. It's really a modified MOV GS,... instruction that loads the base, limit, selector, and attributes; it just loads the base into a different place.

Ok, "Load user space GS base" it is. Considering how you can't load any other
GS.base due to it GPing for CPL > 0.

--
Regards/Gruss,
Boris.

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