linux-kernel - Re: [PATCH] arm64/sme: Move storage of reg_smidr to __cpuinfo_store

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Message-ID: <709a0e75-0d0c-4bff-b9fd-3bbb55c97bd5@sirena.org.uk>
Date: Mon, 16 Dec 2024 12:17:54 +0000
From: Mark Brown <broonie@...nel.org>
To: Marc Zyngier <maz@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Peter Collingbourne <pcc@...gle.com>,
	Mark Rutland <mark.rutland@....com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] arm64/sme: Move storage of reg_smidr to
 __cpuinfo_store_cpu()

On Sat, Dec 14, 2024 at 10:56:13AM +0000, Marc Zyngier wrote:

> I don't understand the need to single out SMIDR_EL1. It seems to only
> make things even more fragile than they already are by adding more
> synchronisation phases.

> Why isn't the following a good enough fix? It makes it plain that
> boot_cpu_data is only a copy of CPU0's initial boot state.

That would work but it's not clear to me that that is what the intent is
here.  The current ordering seemed like a strange enough decision to be
deliberate, though I couldn't identify the reasoning.

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