Re: [PATCH 1/2] ARM: ITS: implement quirks and add support for Renesas Gen4 ITS

[Jan Beulich <jbeulich@xxxxxxxx>]

On 13.12.2024 14:43, Mykyta Poturai wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> 
> There are number of ITS implementations exist which are different from
> the base one which have number of functionalities defined as is
> "IMPLEMENTATION DEFINED", e.g. there may exist differences in cacheability,
> shareability and memory requirements and others. This requires
> appropriate handling of such HW requirements which are implemented as
> ITS quirks: GITS_IIDR (ITS Implementer Identification Register) is used to
> differentiate the ITS implementations and select appropriate set of
> quirks if any.
> 
> As an example of such ITSes add quirk implementation for Renesas Gen4 ITS:
> - add possibility to override default cacheability and shareability
> settings used for ITS memory allocations;
> - add possibility to allocate memory used by ITS with specific memory
> requirements: introduce _x{z|m}alloc_whole_pages functions and free the
> memory with xfree as usual.

I disagree with this part. If you need whole pages, you want to use
alloc_{dom,xen}heap_pages(). They also provide control over "specific
requirements", which xmalloc() et al (deliberately don't offer, while
you end up making that inconsistent by adding memflags to two of the
interfaces there). And btw, if anything you'd need to alter the
xvmalloc() set of interfaces, as new code is supposed to use them in
favor of the xmalloc() family.

Jan