From: Thomas Gleixner <tglx@linutronix.de>
To: Eric Biggers <ebiggers@kernel.org>, Borislav Petkov <bp@alien8.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
Jain@formenos.rohan.me.apana.org.au, Ayush <Ayush.Jain3@amd.com>,
Stephen Rothwell <sfr@canb.auug.org.au>, x86-ml <x86@kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
linux-crypto@vger.kernel.org
Subject: Re: [PATCH] crypto: lib/sha256 - Disable SIMD
Date: Fri, 16 May 2025 22:34:31 +0200 [thread overview]
Message-ID: <878qmwi9bc.ffs@tglx> (raw)
In-Reply-To: <20250516190637.GA32835@sol>
On Fri, May 16 2025 at 12:06, Eric Biggers wrote:
> What would you say about going back to my earlier plan to make irq_fpu_usable()
> return false when irqs_disabled(), like what arm64 does? (As I had in
> https://lore.kernel.org/lkml/20250220051325.340691-2-ebiggers@kernel.org/).
> + return !this_cpu_read(in_kernel_fpu) &&
> + !in_hardirq() && !irqs_disabled() && !in_nmi();
The !in_hardirq() is redundant because hard interrupt context runs with
interrupts disabled.
> I think that would handle all these cases, as well as others. We'd need to fix
> __save_processor_state() to save the FPU state directly without pretending that
> it's using kernel-mode FPU, but I don't know of any issues besides
> that.
Looks about right.
> Then we could also delete the irqs_disabled() checks that I added to
> kernel_fpu_begin() and kernel_fpu_end().
Yes. That conditional locking is horrible.
Thanks,
tglx
prev parent reply other threads:[~2025-05-16 20:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-16 11:22 cryptodev linux-next splat Borislav Petkov
2025-05-16 11:34 ` Herbert Xu
2025-05-16 11:48 ` [PATCH] crypto: lib/sha256 - Disable SIMD Herbert Xu
2025-05-16 12:27 ` Borislav Petkov
2025-05-16 17:03 ` Eric Biggers
2025-05-16 18:13 ` Borislav Petkov
2025-05-16 19:06 ` Eric Biggers
2025-05-16 20:34 ` Thomas Gleixner [this message]
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