linux-kernel - Re: [PATCH v3] arm64: errata: Work around AmpereOne's erratum AC04_CPU

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Message-ID: <aB3UBSQYtTveKPlh@linux.dev>
Date: Fri, 9 May 2025 03:08:05 -0700
From: Oliver Upton <oliver.upton@...ux.dev>
To: D Scott Phillips <scott@...amperecomputing.com>
Cc: Catalin Marinas <catalin.marinas@....com>,
	James Clark <james.clark@...aro.org>,
	James Morse <james.morse@....com>, Joey Gouly <joey.gouly@....com>,
	Kevin Brodsky <kevin.brodsky@....com>,
	Marc Zyngier <maz@...nel.org>, Mark Brown <broonie@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	"Rob Herring  (Arm)" <robh@...nel.org>,
	Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>,
	Shiqi Liu <shiqiliu@...t.edu.cn>, Will Deacon <will@...nel.org>,
	Yicong Yang <yangyicong@...ilicon.com>, kvmarm@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] arm64: errata: Work around AmpereOne's erratum
 AC04_CPU_23

Hey D Scott,

On Thu, May 08, 2025 at 02:00:09PM -0700, D Scott Phillips wrote:
> On AmpereOne AC04, updates to HCR_EL2 can rarely corrupt simultaneous
> translations for data addresses initiated by load/store instructions.
> Only instruction initiated translations are vulnerable, not translations
> from prefetches for example. A DSB before the store to HCR_EL2 is
> sufficient to prevent older instructions from hitting the window for
> corruption, and an ISB after is sufficient to prevent younger
> instructions from hitting the window for corruption.
> 
> Signed-off-by: D Scott Phillips <scott@...amperecomputing.com>

Overall looks good, still needs an entry in Documentation/arch/arm64/silicon-errata.rst
which Marc noted in v2.

With that addressed:

Reviewed-by: Oliver Upton <oliver.upton@...ux.dev>

Thanks,
Oliver