netdev - Re: [PATCH v8 0/7] Optimize dm-verity and fsverity using multibuffer hashing

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Message-ID: <CAMj1kXFe2f0cCYznorrO-wJyh-qxJP5z-HdR9rbQiuMKC5u6qw@mail.gmail.com>
Date: Tue, 18 Feb 2025 08:41:57 +0100
From: Ard Biesheuvel <ardb@...nel.org>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Jakub Kicinski <kuba@...nel.org>, Eric Biggers <ebiggers@...nel.org>, fsverity@...ts.linux.dev, 
	linux-crypto@...r.kernel.org, dm-devel@...ts.linux.dev, x86@...nel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Sami Tolvanen <samitolvanen@...gle.com>, Alasdair Kergon <agk@...hat.com>, 
	Mike Snitzer <snitzer@...nel.org>, Linus Torvalds <torvalds@...ux-foundation.org>, 
	Mikulas Patocka <mpatocka@...hat.com>, David Howells <dhowells@...hat.com>, netdev@...r.kernel.org
Subject: Re: [PATCH v8 0/7] Optimize dm-verity and fsverity using multibuffer hashing

On Tue, 18 Feb 2025 at 04:43, Herbert Xu <herbert@...dor.apana.org.au> wrote:
>
> On Mon, Feb 17, 2025 at 09:40:32AM -0800, Jakub Kicinski wrote:
> >
> > Yes, that's true for tunnels and for IPsec.
> > TLS does crypto in sendmsg/recvmsg, process context.
>
> OK that's good to know.  So whether SIMD is always allowed or
> not won't impact TLS at least.
>

And for IPsec, I'd assume that the cryptd fallback is only needed when
TX and RX are competing for the same CPU.

So for modern systems, I don't think the SIMD helper does anything
useful, and we should just remove it, especially if we can relax the
softirq/preemption rules for kernel SIMD on x86 like I did for arm64.