[PATCH v4] arm64: errata: Work around AmpereOne's erratum AC04_CPU_23

[D Scott Phillips]

Jaikiran Pai <jai.forums2013 at gmail.com> writes:

> Hello Scott,
>
> On 14/05/25 12:15 am, 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.
>
> I see that this patch enables the workaround only for AmpereOne AC04 
> systems. Do you happen to know if the underlying issue for which this 
> patch was introduced, impacts (or can impact) AmpereOne AC03 systems too:

Hi Jaikiran, this issue impacts ac04 only, it is not present on ac03.