linux-kernel - Re: [PATCH] x86/fpu: Use consistent test for X86_FEATURE

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Date:   Wed, 3 Feb 2021 12:23:40 +0100
From:   Borislav Petkov <bp@...e.de>
To:     "Chang S. Bae" <chang.seok.bae@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     x86@...nel.org, luto@...nel.org, mingo@...nel.org,
        tglx@...utronix.de, len.brown@...el.com, dave.hansen@...el.com,
        ravi.v.shankar@...el.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/fpu: Use consistent test for X86_FEATURE_XSAVES

On Tue, Feb 02, 2021 at 06:40:52PM -0800, Chang S. Bae wrote:
> When XSAVES is present, the kernel always takes advantage of it, and XSAVES
> always uses compacted format.
> 
> The macro using_compacted_format() implies that using compacted format may

Not a macro.

> be possible without XSAVES (say by using XSAVEC), but that is not possible
> here, so delete that confusing macro and simply test for what we want to
> know in the first place -- if we have XSAVES or not.

Who's "we"?

> @@ -500,20 +500,6 @@ int xfeature_size(int xfeature_nr)
>  	return eax;
>  }
>  
> -/*
> - * 'XSAVES' implies two different things:
> - * 1. saving of supervisor/system state
> - * 2. using the compacted format
> - *
> - * Use this function when dealing with the compacted format so
> - * that it is obvious which aspect of 'XSAVES' is being handled
> - * by the calling code.

@dhansen, are you still hung up on that "obvious aspect" or can we kill
this?

-- 
Regards/Gruss,
    Boris.

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