[PATCH v3] arm64: errata: Workaround NVIDIA Olympus device store/load ordering erratum

[Jason Gunthorpe]

On Thu, Jun 11, 2026 at 08:13:48PM -0500, Shanker Donthineni wrote:

> For the scalar MMIO helpers, the workaround promotes the raw writes to
> store-release on affected CPUs as v1/v2 shown below. For the memcpy-toIO
> helpers, could you please clarify the specific reason for adding a dmb despite
> the documented no-ordering contract? Is the concern that some drivers may
> be relying on ordering across memcpy_toio_*() today even though the API
> does not guarantee it, and that we should cover those cases defensively?

I think given how arm implements them today the iocopy's are actually
the _relaxed variations.. I wonder if this matters to any user?

Jason