linux-kernel - Re: [PATCH v2 0/9] crypto: x86

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Message-ID: <Z-yrf_9D2rV1Q136@gondor.apana.org.au>
Date: Wed, 2 Apr 2025 11:14:07 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Eric Biggers <ebiggers@...nel.org>
Cc: linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
	x86@...nel.org, Ard Biesheuvel <ardb@...nel.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Danny Tsen <dtsen@...ux.ibm.com>
Subject: Re: [PATCH v2 0/9] crypto: x86 - stop using the SIMD helper

Eric Biggers <ebiggers@...nel.org> wrote:
>
> Stop wrapping skcipher and aead algorithms with the crypto simd helper
> (crypto/simd.c).  The only purpose of doing so was to work around x86
> not always supporting kernel-mode FPU in softirqs.  Specifically, if a
> hardirq interrupted a task context kernel-mode FPU section and then a
> softirqs were run at the end of that hardirq, those softirqs could not
> use kernel-mode FPU.  This has now been fixed.  In combination with the
> fact that the skcipher and aead APIs only support task and softirq
> contexts, these can now just use kernel-mode FPU unconditionally on x86.

Nice work!

So which platform still needs the simd wrapper? I believe arm/arm64
have both been fixed but we haven't finished removing the legacy
simd code yet? Ard, would you be able to spare some cycles and
finish the removal of simd on arm?

Darn, it looks like powerpc has just started using the simd wrapper
so we need to fix it first before we can completely eliminate simd.

Michael/Danny, any chance you guys could implement something similar
to what's been done on arm/x86 and make simd usable in softirqs?

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt