linux-kernel - Re: [RFC V1 1/7] x86: Probe assembler capabilities for VAES and VPLCMULQDQ support

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Date:   Wed, 20 Jan 2021 14:38:44 -0800
From:   "Dey, Megha" <megha.dey@...el.com>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ravi.v.shankar@...el.com, tim.c.chen@...el.com,
        andi.kleen@...el.com, Dave Hansen <dave.hansen@...el.com>,
        wajdi.k.feghali@...el.com, greg.b.tucker@...el.com,
        robert.a.kasten@...el.com, rajendrakumar.chinnaiyan@...el.com,
        tomasz.kantecki@...el.com, ryan.d.saffores@...el.com,
        ilya.albrekht@...el.com, kyung.min.park@...el.com,
        Tony Luck <tony.luck@...el.com>, ira.weiny@...el.com,
        X86 ML <x86@...nel.org>
Subject: Re: [RFC V1 1/7] x86: Probe assembler capabilities for VAES and
 VPLCMULQDQ support

Hi Ard,

On 1/16/2021 8:54 AM, Ard Biesheuvel wrote:
> On Fri, 18 Dec 2020 at 22:07, Megha Dey <megha.dey@...el.com> wrote:
>> This is a preparatory patch to introduce the optimized crypto algorithms
>> using AVX512 instructions which would require VAES and VPLCMULQDQ support.
>>
>> Check for VAES and VPCLMULQDQ assembler support using AVX512 registers.
>>
>> Cc: x86@...nel.org
>> Signed-off-by: Megha Dey <megha.dey@...el.com>
>> ---
>>   arch/x86/Kconfig.assembler | 10 ++++++++++
>>   1 file changed, 10 insertions(+)
>>
>> diff --git a/arch/x86/Kconfig.assembler b/arch/x86/Kconfig.assembler
>> index 26b8c08..9ea0bc8 100644
>> --- a/arch/x86/Kconfig.assembler
>> +++ b/arch/x86/Kconfig.assembler
>> @@ -1,6 +1,16 @@
>>   # SPDX-License-Identifier: GPL-2.0
>>   # Copyright (C) 2020 Jason A. Donenfeld <Jason@...c4.com>. All Rights Reserved.
>>
>> +config AS_VAES_AVX512
>> +       def_bool $(as-instr,vaesenc %zmm0$(comma)%zmm1$(comma)%zmm1) && 64BIT
> Is the '&& 64BIT' necessary here, but not below?
>
> In any case, better to use a separate 'depends on' line, for legibility

yeah , I think the '&& 64 BIT' is not required. I will remove it in the 
next version.

-Megha

>
>> +       help
>> +         Supported by binutils >= 2.30 and LLVM integrated assembler
>> +
>> +config AS_VPCLMULQDQ
>> +       def_bool $(as-instr,vpclmulqdq \$0$(comma)%zmm2$(comma)%zmm6$(comma)%zmm4)
>> +       help
>> +         Supported by binutils >= 2.30 and LLVM integrated assembler
>> +
>>   config AS_AVX512
>>          def_bool $(as-instr,vpmovm2b %k1$(comma)%zmm5)
>>          help
>> --
>> 2.7.4
>>