Re: [PATCH v4 10/16] xen/mm: Switch map_pages_to_xen to use MFN typesafe

[Julien Grall <julien.grall@arm.com>]

Hi,

On 05/03/18 14:39, Jan Beulich wrote:
>>>> On 05.03.18 at 15:07, <julien.grall@arm.com> wrote:
>> On 02/03/18 15:06, Jan Beulich wrote:
>>>>>> On 21.02.18 at 15:02, <julien.grall@arm.com> wrote:
>>>> --- a/xen/arch/x86/x86_64/mm.c
>>>> +++ b/xen/arch/x86/x86_64/mm.c
>>>> @@ -40,6 +40,10 @@ asm(".file \"" __FILE__ "\"");
>>>>    #include <asm/mem_sharing.h>
>>>>    #include <public/memory.h>
>>>>    
>>>> +/* Override macros from asm/page.h to make them work with mfn_t */
>>>> +#undef page_to_mfn
>>>> +#define page_to_mfn(pg) _mfn(__page_to_mfn(pg))
>>>
>>> I can't spot where this is needed in this file.
>>>
>>>> @@ -234,7 +238,7 @@ void vunmap(const void *va)
>>>>    #ifndef _PAGE_NONE
>>>>        destroy_xen_mappings(addr, addr + PAGE_SIZE * pages);
>>>>    #else /* Avoid tearing down intermediate page tables. */
>>>> -    map_pages_to_xen(addr, 0, pages, _PAGE_NONE);
>>>> +    map_pages_to_xen(addr, _mfn(0), pages, _PAGE_NONE);
>>>
>>> INVALID_MFN?
>>
>> I can but then we end up to the same clumsiness as you mention in #8. So
>> what's your preference?
> 
> My preference is to skip the increments for INVALID_MFN in patch 8.
> Since you don't want to do that, I guess we'll have to live with zero
> being used everywhere.

It is not that I don't want. I don't have any x86 setup and not that 
confident to provide a change bigger than switch from plain unsigned int 
to typesafe and light clean-up.

I can provide a patch if you really want. But likely it is going to be 
quicker for you to write it.

Cheers,

-- 
Julien Grall

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