Re: [PATCH 3/5] hw/cxl: Allow BI by default in Window restrictions

[Markus Armbruster <armbru@redhat.com>]

Jonathan Cameron <jonathan.cameron@huawei.com> writes:

> On Thu, 18 Dec 2025 10:18:17 +0100
> Markus Armbruster <armbru@redhat.com> wrote:
>
>> Davidlohr Bueso <dave@stgolabs.net> writes:
>> 
>> > Update the CFMW restrictions to also permit Back-Invalidate
>> > flows by default, which is aligned with the no-restrictions
>> > policy.
>> >
>> > While at it, document the 'restrictions=' option.  
>> 
>> I'd split the patch.  Up to you.
> Hi Markus,
>
> As you note below the interface hasn't been in any release anyway and
> is part of the long backlog I'm carrying and slowly getting
> upstream. Bringing this in from the start with that restrictions
> control should be fine.
>
> However, backwards compatibility does need addressing
> as this changes the default for things we do create today (with
> no restrictions).
>
> In this particular case, I don't think we care because there are no
> BI capable devices before this series - so there can't be anything
> using this feature for the host memory range it describes.
>
> As such, the only result is the ACPI table says we have an extra
> flag set which no one will care about.  Will need to update
> the ACPI table tests though. I'll check.
>
> Migration of CXL topologies is horribly broken currently anyway
> so that's not a problem here. Given current usecases are strictly
> software stack verification fixing that isn't a priority (yet).

Good to know.  Work into commit message(s)?