linux-kernel - Re: [PATCHv6 01/16] x86/cpu: Enumerate the LASS feature bits

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Message-ID: <6y2iqv6c2idn7yebaec7tyhzl5zcsrwqq4lcsokumlqeophzaf@ljnmxorblgcj>
Date: Fri, 20 Jun 2025 20:33:36 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Borislav Petkov <bp@...en8.de>
Cc: Andy Lutomirski <luto@...nel.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
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	linux-mm@...ck.org, Yian Chen <yian.chen@...el.com>
Subject: Re: [PATCHv6 01/16] x86/cpu: Enumerate the LASS feature bits

On Fri, Jun 20, 2025 at 06:35:04PM +0200, Borislav Petkov wrote:
> On Fri, Jun 20, 2025 at 04:53:09PM +0300, Kirill A. Shutemov wrote:
> > diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> > index ee176236c2be..4473a6f7800b 100644
> > --- a/arch/x86/include/asm/cpufeatures.h
> > +++ b/arch/x86/include/asm/cpufeatures.h
> > @@ -313,6 +313,7 @@
> >  #define X86_FEATURE_SM4			(12*32+ 2) /* SM4 instructions */
> >  #define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* "avx_vnni" AVX VNNI instructions */
> >  #define X86_FEATURE_AVX512_BF16		(12*32+ 5) /* "avx512_bf16" AVX512 BFLOAT16 instructions */
> > +#define X86_FEATURE_LASS		(12*32+ 6) /* "lass" Linear Address Space Separation */
> 
> This needs to be in /proc/cpuinfo because...?

What is current policy around it ?

I think it is useful to advertise security features in cpuinfo. LASS fits
next to SMAP/SMEP/UMIP.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov