RE: [PATCH 09/37] xen/x86: introduce two helpers to access memory hotplug end

[Wei Chen <Wei.Chen@xxxxxxx>]

Hi Jan,

> -----Original Message-----
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: 2022年1月25日 0:25
> To: Wei Chen <Wei.Chen@xxxxxxx>
> Cc: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>; xen-
> devel@xxxxxxxxxxxxxxxxxxxx; sstabellini@xxxxxxxxxx; julien@xxxxxxx
> Subject: Re: [PATCH 09/37] xen/x86: introduce two helpers to access memory
> hotplug end
> 
> On 23.09.2021 14:02, Wei Chen wrote:
> > x86 provides a mem_hotplug to maintain the end of memory hotplug
> > end address. This variable can be accessed out of mm.c. We want
> > some code out of mm.c can be reused by other architectures without
> > memory hotplug ability. So in this patch, we introduce these two
> > helpers to replace mem_hotplug direct access. This will give the
> > ability to stub these two API.
> >
> > Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> > ---
> >  xen/include/asm-x86/mm.h | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
> > index cb90527499..af2fc4b0cd 100644
> > --- a/xen/include/asm-x86/mm.h
> > +++ b/xen/include/asm-x86/mm.h
> > @@ -475,6 +475,16 @@ static inline int get_page_and_type(struct
> page_info *page,
> >
> >  extern paddr_t mem_hotplug;
> >
> > +static inline void mem_hotplug_update_boundary(paddr_t end)
> > +{
> > +    mem_hotplug = end;
> > +}
> > +
> > +static inline paddr_t mem_hotplug_boundary(void)
> > +{
> > +    return mem_hotplug;
> > +}
> > +
> >
> /*************************************************************************
> *****
> >   * With shadow pagetables, the different kinds of address start
> >   * to get get confusing.
> 
> Imo for this to make sense you want to also use the new functions
> right away in the place(s) where the direct access(es) get(s) in
> your way.
> 

OK, I will merge this patch with the patch that will use these
functions firstly. 

> Jan