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

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Message-ID: <CAMj1kXGJD1FdixURybqZEOJV+h1-QESp=WCJVPo-Bvd7Zh9j1Q@mail.gmail.com>
Date:   Sat, 16 Jan 2021 17:54:38 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Megha Dey <megha.dey@...el.com>
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

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

> +       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
>