Re: [RFC PATCH v4 02/27] x86/fpu/xstate: Change some names to separate XSAVES system and user states

Borislav Petkov
2018-10-02T16:37:52Z

On Tue, Oct 02, 2018 at 09:30:52AM -0700, Dave Hansen wrote:
> > Good point. However, "system" is more indicative; CET states are per-task and
> > not "Supervisor". Do we want to go back to "Supervisor" or add comments?
>
> This is one of those things where the SDM language does not match what
> we use in the kernel. I think it's fine to call them "system" or
> "kernel" states to make it consistent with our existing in-kernel
> nomenclature.
>
> I say add comments to clarify what the SDM calls it vs. what we do.

So AFAIU, the difference is that XSAVES is a CPL0 insn. Thus the
supervisor thing, I'd guess.

Now it looks like CET uses XSAVES (from skimming the patchset forward)
but then what our nomenclature is and how it all gets tied together,
needs to be explained somewhere prominent so that we're all on the same
page.

This patch's commit message is not even close. So I'd very much
appreciate a more verbose explanation, even if it repeats itself at
places.

Thx.

--
Regards/Gruss,
Boris.

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