linux-kernel - Re: [PATCH v3 11/15] crypto: x86/aes-kl - Support AES algorithm using Key Locker instructions

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Message-ID: <YaWfKB+k66MzNtIi@sol.localdomain>
Date:   Mon, 29 Nov 2021 19:48:56 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     "Chang S. Bae" <chang.seok.bae@...el.com>
Cc:     tglx@...utronix.de, bp@...e.de, dave.hansen@...ux.intel.com,
        mingo@...nel.org, luto@...nel.org, x86@...nel.org,
        herbert@...dor.apana.org.au, linux-kernel@...r.kernel.org,
        linux-crypto@...r.kernel.org, dan.j.williams@...el.com,
        charishma1.gairuboyina@...el.com, kumar.n.dwarakanath@...el.com,
        lalithambika.krishnakumar@...el.com, ravi.v.shankar@...el.com
Subject: Re: [PATCH v3 11/15] crypto: x86/aes-kl - Support AES algorithm
 using Key Locker instructions

On Wed, Nov 24, 2021 at 12:06:56PM -0800, Chang S. Bae wrote:
> diff --git a/arch/x86/crypto/Makefile b/arch/x86/crypto/Makefile
> index ef6c0b9f69c6..f696b037faa5 100644
> --- a/arch/x86/crypto/Makefile
> +++ b/arch/x86/crypto/Makefile
> @@ -50,6 +50,9 @@ obj-$(CONFIG_CRYPTO_AES_NI_INTEL) += aesni-intel.o
>  aesni-intel-y := aesni-intel_asm.o aesni-intel_glue.o aes-intel_glue.o
>  aesni-intel-$(CONFIG_64BIT) += aesni-intel_avx-x86_64.o aes_ctrby8_avx-x86_64.o
>  
> +obj-$(CONFIG_CRYPTO_AES_KL) += aeskl-intel.o
> +aeskl-intel-y := aeskl-intel_asm.o aesni-intel_asm.o aeskl-intel_glue.o aes-intel_glue.o

This makes the object files aesni-intel_asm.o and aes-intel_glue.o each be built
into two separate kernel modules.  My understanding is that duplicating code
like that is generally frowned upon.  These files should either be built into a
separate module, which both aesni-intel.ko and aeskl-intel.ko would depend on,
or aeskl-intel.ko should depend on aesni-intel.ko.

> diff --git a/arch/x86/crypto/aeskl-intel_asm.S b/arch/x86/crypto/aeskl-intel_asm.S
> new file mode 100644
> index 000000000000..d56ec8dd6644
> --- /dev/null
> +++ b/arch/x86/crypto/aeskl-intel_asm.S

This file gets very long after all the modes are added (> 1100 lines).  Is there
really no feasible way to share code between this and aesni-intel_asm.S, similar
to how the arm64 AES implementations work?  Surely most of the logic is the
same, and it's just the actual AES instructions that differ?

> +config CRYPTO_AES_KL
> +	tristate "AES cipher algorithms (AES-KL)"
> +	depends on (LD_VERSION >= 23600) || (LLD_VERSION >= 120000)
> +	depends on DM_CRYPT

'depends on DM_CRYPT' doesn't really make sense here, since there is no actual
dependency on dm-crypt in the code.

- Eric