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

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>


--- 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



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