Re: [PATCH RFCv2 02/15] xen/arm: lpae: Use the generic helpers to defined the Xen PT helpers

[Julien Grall <julien@xxxxxxx>]

Hi Stefano,

On 12/05/2021 22:30, Stefano Stabellini wrote:
> On Wed, 12 May 2021, Julien Grall wrote:
> > > > +#define LPAE_SHIFT          LPAE_SHIFT_GS(PAGE_SHIFT)
> > > > +#define LPAE_ENTRIES        LPAE_ENTRIES_GS(PAGE_SHIFT)
> > > > +#define LPAE_ENTRY_MASK     LPAE_ENTRY_MASK_GS(PAGE_SHIFT)
> > > >
> > > > +#define LEVEL_SHIFT(lvl)    LEVEL_SHIFT_GS(PAGE_SHIFT, lvl)
> > > > +#define LEVEL_ORDER(lvl)    LEVEL_ORDER_GS(PAGE_SHIFT, lvl)
> > > > +#define LEVEL_SIZE(lvl)     LEVEL_SIZE_GS(PAGE_SHIFT, lvl)
> > > > +#define LEVEL_MASK(lvl)     (~(LEVEL_SIZE(lvl) - 1))
> > > I would avoid adding these 4 macros. It would be OK if they were just
> > > used within this file but lpae.h is a header: they could end up be used
> > > anywhere in the xen/ code and they have a very generic name. My
> > > suggestion would be to skip them and just do:
> > Those macros will be used in follow-up patches. They are pretty useful to
> > avoid introduce static array with the different information for each level.
> >
> > Would prefix them with XEN_ be better?
> Maybe. The concern I have is that there are multiple page granularities
> (4kb, 16kb, etc) and multiple page sizes (4kb, 2mb, etc). If I just see
> LEVEL_ORDER it is not immediately obvious what granularity and what size
> we are talking about.
I am a bit puzzled with your answer. AFAIU, you are happy with the 
existing macros (THIRD_*, SECOND_*) but not with the new macros.
In reality, there is no difference because THIRD_* doesn't tell you the 
exact size but only "this is a level 3 mapping".
So can you clarify what you are after? IOW is it reworking the current 
naming scheme?
Cheers,

--
Julien Grall