linux-kernel - Re: [PATCH] x86/cpufeatures: Move the definition of X86_FEATURE_AMX

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Date:   Tue, 8 Feb 2022 17:06:04 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Borislav Petkov <bp@...en8.de>, Jim Mattson <jmattson@...gle.com>
Cc:     Dave Hansen <dave.hansen@...el.com>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Jing Liu <jing2.liu@...el.com>, linux-kernel@...r.kernel.org,
        "Bae, Chang Seok" <chang.seok.bae@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] x86/cpufeatures: Move the definition of X86_FEATURE_AMX_*
 to the word 18

On 8/2/2022 4:51 pm, Borislav Petkov wrote:
> On Tue, Feb 08, 2022 at 04:08:17PM +0800, Like Xu wrote:
>> Emm, are you willing to make "test-apply.sh" public (or have done) and let
>> others benefit ?
> 
> It is nothing special - just a simple script which does first
> 
> patch -p1 --dry-run -l -i [patch file]
> 
> to see whether it would even apply.
> 
>> Sorry for the late reply, and here's a new version from git-send-email:
> 
> Yeah, someone already took care of this:
> 
> https://git.kernel.org/tip/ae75fa54228162ecd65341f9780886f21f557cc4
> 

Uh, it's Jim and we have worked together on many KVM issues.

BTW, I'm not sure why we prefer:

#define X86_FEATURE_AVX512_FP16		(18*32+23) /* AVX512 FP16 */
#define X86_FEATURE_SPEC_CTRL		(18*32+26) /* "" Speculation Control (IBRS + IBPB) */
+#define X86_FEATURE_AMX_BF16		(18*32+22) /* AMX bf16 Support */
+#define X86_FEATURE_AMX_TILE		(18*32+24) /* AMX tile Support */
+#define X86_FEATURE_AMX_INT8		(18*32+25) /* AMX int8 Support */

rather than:

+#define X86_FEATURE_AMX_BF16        (18*32+22) /* AMX bf16 Support */
  #define X86_FEATURE_AVX512_FP16		(18*32+23) /* AVX512 FP16 */
+#define X86_FEATURE_AMX_TILE        (18*32+24) /* AMX tile Support */
+#define X86_FEATURE_AMX_INT8        (18*32+25) /* AMX int8 Support */

It would make more sense to put them in order, what do you think? Need v3 to 
sort it ?

Thanks,
Like Xu