Re: [Xen-devel] [PATCH v12 5/9] memory: add check_get_page_from_gfn() as a wrapper...

[Julien Grall <julien.grall@xxxxxxx>]

Hi Paul,

On 09/27/2018 03:33 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.
>
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Reviewed-by: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Tim Deegan <tim@xxxxxxx>
> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
>
> v11:
>   - Forward declare p2m_type_t in p2m-common.h to allow the duplicate
>     declarations of check_get_page_from_gfn() to be removed, and hence add
>     Jan's R-b.
I think this would be worth adding a word in the commit message about 
the forward declaration.
For the Arm bits:

Acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

--
Julien Grall

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