[PATCH v3] arm64: errata: Work around AmpereOne's erratum AC04_CPU_23

[D Scott Phillips]

Oliver Upton <oliver.upton at linux.dev> writes:

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

Ah, sorry for missing that and making you repeat yourself. I'll fix
that.