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Re: [PATCH 1/3] xen/arm: Fix off-by-one in iomem_deny_access() calls


  • To: Michal Orzel <michal.orzel@xxxxxxx>
  • From: Luca Fancellu <Luca.Fancellu@xxxxxxx>
  • Date: Thu, 9 Apr 2026 13:34:15 +0000
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  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
  • Delivery-date: Thu, 09 Apr 2026 13:35:25 +0000
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  • Thread-topic: [PATCH 1/3] xen/arm: Fix off-by-one in iomem_deny_access() calls

Hi Michal,

> On 9 Apr 2026, at 12:39, Michal Orzel <michal.orzel@xxxxxxx> wrote:
> 
> iomem_deny_access() wraps rangeset_remove_range() which takes inclusive
> endpoints.  All call sites in the GIC and ACPI code pass 'mfn + nr' (or
> 'mfn + 1' for single-page regions) as the end parameter, which causes
> one extra page beyond each region to be denied.
> 
> For single-page regions, use 'mfn' as the end (denying exactly one page).
> For all multi-page regions, use 'mfn + nr - 1'.
> 
> This matches the correct pattern used elsewhere, e.g. in device.c.
> 
> Fixes: 8300b3377e ("arm/gic: Add a new callback to deny Dom0 access to GIC 
> regions")
> Fixes: 66158be465 ("ARM: ITS: Deny hardware domain access to ITS")
> Fixes: 97e9875646 ("arm/acpi: Permit MMIO access of Xen unused devices for 
> Dom0")
> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
> ---
> 

This looks ok to me.

Reviewed-by: Luca Fancellu <luca.fancellu@xxxxxxx>

Cheers,
Luca





 


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