Re: [Xen-devel] [PATCH v9 5/7] memory: add check_get_page_from_gfn() as a wrapper...

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: 19 September 2018 07:03
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>; Andrew Cooper
> <Andrew.Cooper3@xxxxxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxx>; Ian
> Jackson <Ian.Jackson@xxxxxxxxxx>; Wei Liu <wei.liu2@xxxxxxxxxx>; Stefano
> Stabellini <sstabellini@xxxxxxxxxx>; xen-devel <xen-
> devel@xxxxxxxxxxxxxxxxxxxx>; Konrad Rzeszutek Wilk
> <konrad.wilk@xxxxxxxxxx>; Tim (Xen.org) <tim@xxxxxxx>
> Subject: RE: [Xen-devel] [PATCH v9 5/7] memory: add
> check_get_page_from_gfn() as a wrapper...
> 
> >>> On 18.09.18 at 18:37, <Paul.Durrant@xxxxxxxxxx> wrote:
> >>  -----Original Message-----
> >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> Sent: 18 September 2018 15:51
> >> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> >> Cc: Julien Grall <julien.grall@xxxxxxx>; Andrew Cooper
> >> <Andrew.Cooper3@xxxxxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxx>;
> Ian
> >> Jackson <Ian.Jackson@xxxxxxxxxx>; Wei Liu <wei.liu2@xxxxxxxxxx>;
> Stefano
> >> Stabellini <sstabellini@xxxxxxxxxx>; xen-devel <xen-
> >> devel@xxxxxxxxxxxxxxxxxxxx>; Konrad Rzeszutek Wilk
> >> <konrad.wilk@xxxxxxxxxx>; Tim (Xen.org) <tim@xxxxxxx>
> >> Subject: RE: [Xen-devel] [PATCH v9 5/7] memory: add
> >> check_get_page_from_gfn() as a wrapper...
> >>
> >> >>> On 18.09.18 at 16:03, <Paul.Durrant@xxxxxxxxxx> wrote:
> >> >>  -----Original Message-----
> >> >> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On
> >> Behalf
> >> >> Of Jan Beulich
> >> >> Sent: 18 September 2018 14:17
> >> >> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> >> >> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>; Wei Liu
> >> >> <wei.liu2@xxxxxxxxxx>; Konrad Rzeszutek Wilk
> <konrad.wilk@xxxxxxxxxx>;
> >> >> George Dunlap <George.Dunlap@xxxxxxxxxx>; Andrew Cooper
> >> >> <Andrew.Cooper3@xxxxxxxxxx>; Ian Jackson <Ian.Jackson@xxxxxxxxxx>;
> Tim
> >> >> (Xen.org) <tim@xxxxxxx>; Julien Grall <julien.grall@xxxxxxx>; xen-
> devel
> >> >> <xen-devel@xxxxxxxxxxxxxxxxxxxx>
> >> >> Subject: Re: [Xen-devel] [PATCH v9 5/7] memory: add
> >> >> check_get_page_from_gfn() as a wrapper...
> >> >>
> >> >> >>> On 13.09.18 at 17:21, <paul.durrant@xxxxxxxxxx> wrote:
> >> >> > --- a/xen/include/asm-arm/p2m.h
> >> >> > +++ b/xen/include/asm-arm/p2m.h
> >> >> > @@ -303,6 +303,10 @@ static inline struct page_info
> >> *get_page_from_gfn(
> >> >> >      return page;
> >> >> >  }
> >> >> >
> >> >> > +int __must_check check_get_page_from_gfn(struct domain *d, gfn_t
> >> gfn,
> >> >> > +                                         bool readonly,
> p2m_type_t
> >> >> *p2mt_p,
> >> >> > +                                         struct page_info
> **page_p);
> >> >> > +
> >> >> >  int get_page_type(struct page_info *page, unsigned long type);
> >> >> >  bool is_iomem_page(mfn_t mfn);
> >> >> >  static inline int get_page_and_type(struct page_info *page,
> >> >> > --- a/xen/include/asm-x86/p2m.h
> >> >> > +++ b/xen/include/asm-x86/p2m.h
> >> >> > @@ -492,6 +492,9 @@ static inline struct page_info
> >> *get_page_from_gfn(
> >> >> >      return mfn_valid(_mfn(gfn)) && get_page(page, d) ? page :
> NULL;
> >> >> >  }
> >> >> >
> >> >> > +int __must_check check_get_page_from_gfn(struct domain *d, gfn_t
> >> gfn,
> >> >> > +                                         bool readonly,
> p2m_type_t
> >> >> *p2mt_p,
> >> >> > +                                         struct page_info
> **page_p);
> >> >> >
> >> >> >  /* General conversion function from mfn to gfn */
> >> >> >  static inline unsigned long mfn_to_gfn(struct domain *d, mfn_t
> mfn)
> >> >>
> >> >> Why twice the same declaration? Can't this be put in xen/p2m-
> common.h?
> >> >> Or some other suitable common header? With that
> >> >> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> >> >>
> >> >
> >> > I was not aware of the common header so I placed it near the
> >> declarations of
> >> > get_page_from_gfn(). Do you want be to submit a v10 with this fixed
> or
> >> are
> >> > you happy to move it to wherever you think is appropriate during
> commit?
> >>
> >> I'd prefer a v10, to be sure things compile fine ahead of trying to
> commit
> >> this series.
> >>
> >
> > Moving to p2m-common won't work. The function declaration involves a
> > p2m_type_t argument and that enum is defined in the arm and x86 specific
> > headers. I propose therefore to leave this patch as-is.
> 
> Leaving the duplication in place is just the last resort imo. Does
> xen/mm.h
> not work either?

No, it won't. It has to be something *after* the definition of the p2m_type_t 
enum. I could, as Julien suggested, move the inclusion of p2m-common after that 
point, but it would mean the header guards would cease to DTRT of course. I'm 
not sure whether C will allow me to forward declare the enum (not something 
I've tried) but I could give that a go. Any other suggestions?

  Paul

> 
> Jan
> 


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