Re: [Xen-devel] [PATCH v10 5/7] memory: add check_get_page_from_gfn() as a wrapper...

[Julien Grall <julien.grall@xxxxxxx>]

Hi Paul,

On 09/18/2018 05:56 PM, Paul Durrant wrote:
> ...for some uses of get_page_from_gfn().
>
> There are many occurrences of the following pattern in the code:
>
>      q = <readonly look-up> ? P2M_ALLOC : P2M_UNSHARE;
>      page = get_page_from_gfn(d, gfn, &p2mt, q);
>
>      if ( p2m_is_paging(p2mt) )
>      {
>          if ( page )
>              put_page(page);
>
>          p2m_mem_paging_populate(d, gfn);
>          return <-EAGAIN or equivalent>;
>      }
>
>      if ( (q & P2M_UNSHARE) && p2m_is_shared(p2mt) )
>      {
>          if ( page )
>              put_page(page);
>
>          return <-EAGAIN or equivalent>;
>      }
>
>      if ( !page )
>          return <-EINVAL or equivalent>;
>
> There are some small differences between the exact way the occurrences
> are coded but the desired semantic is the same.
>
> This patch introduces a new common implementation of this code in
> check_get_page_from_gfn() and then converts the various open-coded patterns
> into calls to this new function.
>
> NOTE: There are duplicate declarations of check_get_page_from_gfn() for
>        ARM and x86 because the function takes a p2m_type_t argument and
>        that type is architecture specific.
Wouldn't it be possible to move #include p2m-common.h later on in p2m.h?

Cheers,

--
Julien Grall

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