Re: [Xen-devel] [PATCH for-next 9/9] xen: Remove mfn_to_gmfn macro

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andrew,

On 13/03/2019 17:34, Andrew Cooper wrote:
> On 13/03/2019 15:59, Jan Beulich wrote:
> > > > > On 13.03.19 at 16:48, <julien.grall@xxxxxxx> wrote:
> > > Hi,
> > >
> > > On 13/03/2019 15:40, Jan Beulich wrote:
> > > > > > > On 13.03.19 at 16:24, <julien.grall@xxxxxxx> wrote:
> > > > > On 13/03/2019 15:22, Jan Beulich wrote:
> > > > > > > > > On 18.02.19 at 12:36, <julien.grall@xxxxxxx> wrote:
> > > > > > > --- a/xen/include/asm-arm/mm.h
> > > > > > > +++ b/xen/include/asm-arm/mm.h
> > > > > > > @@ -321,10 +321,8 @@ struct page_info *get_page_from_gva(struct vcpu *v,
> > > vaddr_t va,
> > > > > > >     #define SHARED_M2P_ENTRY         (~0UL - 1UL)
> > > > > > >     #define SHARED_M2P(_e)           ((_e) == SHARED_M2P_ENTRY)
> > > > > > >     
> > > > > > > -/* Xen always owns P2M on ARM */
> > > > > > > +/* We don't have a M2P on Arm */
> > > > > > >     #define set_gpfn_from_mfn(mfn, pfn) do { (void) (mfn), (void)(pfn); }
> > > while (0)
> > > > > > > -#define mfn_to_gmfn(_d, mfn)  (mfn)
> > > > > > So is the plan to remove the other macro from Arm then as well?
> > > > > Do you mean mfn_to_gfn? If so it does not exist on Arm.
> > > > No, I mean the one in context above - set_gpfn_from_mfn().
> > > It is used in common code, so we would need to #idef the caller.
> > Hmm, right, such #ifdef-ary would be undesirable (and two out of
> > the three common code callers would need it.
> >
> > > I think it is better to provide a NOP implementation. Could be moved somewhere
> > > in the common header though. Any opinions?
> > This would perhaps be better, now that you have HAVE_M2P.
> Given that "having an M2P" is now an x86-specific concept, I think
> phasing set_gpfn_from_mfn()'s use out of common code is the way to go.
So you never expect other architecture to use the M2P?

Cheers,

--
Julien Grall

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