Re: [PATCH] fully replace mfn_to_gmfn()

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 28/06/2021 12:52, Jan Beulich wrote:
> Convert the two remaining uses as well as Arm's stub to the properly
> named and type-safe mfn_to_gfn(), dropping x86's definition (where we
> already have mfn_to_gfn()).
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> --- a/xen/common/domctl.c
> +++ b/xen/common/domctl.c
> @@ -111,7 +111,8 @@ void getdomaininfo(struct domain *d, str
>       info->outstanding_pages = d->outstanding_pages;
>       info->shr_pages         = atomic_read(&d->shr_pages);
>       info->paged_pages       = atomic_read(&d->paged_pages);
> -    info->shared_info_frame = mfn_to_gmfn(d, virt_to_mfn(d->shared_info));
> +    info->shared_info_frame =
> +        gfn_x(mfn_to_gfn(d, _mfn(virt_to_mfn(d->shared_info))));
>       BUG_ON(SHARED_M2P(info->shared_info_frame));
>   
>       info->cpupool = cpupool_get_id(d);
> --- a/xen/common/memory.c
> +++ b/xen/common/memory.c
> @@ -714,13 +714,13 @@ static long memory_exchange(XEN_GUEST_HA
>            */
>           while ( (page = page_list_remove_head(&in_chunk_list)) )
>           {
> -            unsigned long gfn;
> +            gfn_t gfn;
>   
>               mfn = page_to_mfn(page);
> -            gfn = mfn_to_gmfn(d, mfn_x(mfn));
> +            gfn = mfn_to_gfn(d, mfn);
>               /* Pages were unshared above */
> -            BUG_ON(SHARED_M2P(gfn));
> -            if ( guest_physmap_remove_page(d, _gfn(gfn), mfn, 0) )
> +            BUG_ON(SHARED_M2P(gfn_x(gfn)));
> +            if ( guest_physmap_remove_page(d, gfn, mfn, 0) )
>                   domain_crash(d);
>               free_domheap_page(page);
>           }
> --- a/xen/include/asm-arm/mm.h
> +++ b/xen/include/asm-arm/mm.h
> @@ -328,8 +328,7 @@ struct page_info *get_page_from_gva(stru
>   
>   /* Xen always owns P2M on ARM */
>   #define set_gpfn_from_mfn(mfn, pfn) do { (void) (mfn), (void)(pfn); } while 
> (0)
> -#define mfn_to_gmfn(_d, mfn)  (mfn)
> -
> +#define mfn_to_gfn(d, mfn) _gfn(mfn_x(mfn))
I still have a series pending to drop mfn_to_g{,m}fn() on Arm. But it 
has been stuck for quite a while on an agreement on for the toolstack 
interface (see [1]).
Anyway, this function is not worse than before. So:

Acked-by: Julien Grall <julien@xxxxxxx>

Cheers,

[1] 
https://lore.kernel.org/xen-devel/32d4f762-a61d-bfdd-c4a8-38e5edef1aa8@xxxxxxx/
--
Julien Grall