Re: [PATCH] Arm: relax iomem_access_permitted() check

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 18/08/2021 08:52, Jan Beulich wrote:
> Ranges checked by iomem_access_permitted() are inclusive; to permit a
> mapping there's no need for access to also have been granted for the
> subsequent page.
Good catch! OOI, how did you find it?

> Fixes: 80f9c3167084 ("xen/arm: acpi: Map MMIO on fault in stage-2 page table for the 
> hardware domain")
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -1893,7 +1893,7 @@ static bool try_map_mmio(gfn_t gfn)
>           return false;
>   
>       /* The hardware domain can only map permitted MMIO regions */
> -    if ( !iomem_access_permitted(d, mfn_x(mfn), mfn_x(mfn) + 1) )
> +    if ( !iomem_access_permitted(d, mfn_x(mfn), mfn_x(mfn)) )
>           return false;
>   
>       return !map_regions_p2mt(d, gfn, 1, mfn, p2m_mmio_direct_c);
--
Julien Grall