Re: [Xen-devel] [PATCH] xen/arm: map_dev_mmio_region: The iomem permission check should be done on MFN

[Shannon Zhao <zhaoshenglong@xxxxxxxxxx>]

Hi Julien,

On 2016/6/14 19:50, Julien Grall wrote:
> The helper iomem_access_permitted expects MFNs in parameters and not
> GNFs. Thankfully only the hardware domain can call this function and
> it will always be with GFNS == MFNs for now.
> 
> Also, fix the printf to use the MFN range and not the GFN one.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> Cc: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> 
Reviewed-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>

> ---
>     This patch is a good candidate to backport to Xen 4.7. Without
>     it, the hardware domain can map any MMIO because the permission
>     check is done on the GPFNs and not the MNFs.
> ---
>  xen/arch/arm/p2m.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 6a19c57..4c6547d 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -1275,14 +1275,14 @@ int map_dev_mmio_region(struct domain *d,
>  {
>      int res;
>  
> -    if ( !(nr && iomem_access_permitted(d, start_gfn, start_gfn + nr - 1)) )
> +    if ( !(nr && iomem_access_permitted(d, mfn, mfn + nr - 1)) )
>          return 0;
>  
>      res = map_mmio_regions(d, start_gfn, nr, mfn);
>      if ( res < 0 )
>      {
>          printk(XENLOG_G_ERR "Unable to map [%#lx - %#lx] in Dom%d\n",
> -               start_gfn, start_gfn + nr - 1, d->domain_id);
> +               mfn, mfn + nr - 1, d->domain_id);
>          return res;
>      }
>  
> 

-- 
Shannon


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