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

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Message-ID: <CAMj1kXE-vo7E1U++4mAqDH2SXfc=sRZs8KganedJk5z0QF49NA@mail.gmail.com>
Date: Wed, 2 Apr 2025 09:34:30 +0300
From: Ard Biesheuvel <ardb@...nel.org>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Eric Biggers <ebiggers@...nel.org>, linux-crypto@...r.kernel.org, 
	linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH v2 0/9] crypto: x86 - stop using the SIMD helper

On Wed, 2 Apr 2025 at 09:31, Ard Biesheuvel <ardb@...nel.org> wrote:
>
> On Wed, 2 Apr 2025 at 06:14, Herbert Xu <herbert@...dor.apana.org.au> wrote:
> >
> > 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!
> >
>
> Yeah good riddance.
>
> > 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?
> >
>
> Removal of what, exactly?

Ah, never mind - I see some calls on 32-bit ARM to
simd_skcipher_create_compat(), which have become redundant now that
SIMD is guaranteed to be available in softirq context.