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RE: [Xen-devel] [PATCH] xen: grant-table: Check truncation when giving access to a frame

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> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@lists.xen.org] On Behalf Of
> Julien Grall
> Sent: 13 June 2016 11:51
> To: boris.ostrovsky@oracle.com; David Vrabel; jgross@suse.com;
> sstabellini@kernel.org; konrad.wilk@oracle.com
> Cc: steve.capper@arm.com; Andrew Cooper; linux-kernel@vger.kernel.org;
> xen-devel@lists.xen.org; Julien Grall; JBeulich@suse.com
> Subject: [Xen-devel] [PATCH] xen: grant-table: Check truncation when giving
> access to a frame
> 
> The version 1 of the grant-table protocol only supports frame encoded on
> 32-bit.
> 
> When the platform is supporting 48-bit physical address, the frame will
> be encoded on 36-bit which will lead a truncation and give access to
> the wrong frame.
> 
> On ARM Xen will always allow the guest to use all the physical address,
> although today the RAM is always located under 40-bits (see
> xen/include/public/arch-arm.h).
> 
> Add a truncation check in gnttab_update_entry_v1 to prevent the guest to
> give access to the wrong frame.
> 
> Signed-off-by: Julien Grall <julien.grall@arm.com>
> 
> ---
>     This is limiting us to a 44-bit address space whilst ARM can support
>     up to 48-bit today. This number of bit will increase to 52-bit in
>     upcoming processors [1].
> 
>     It might be good to start thinking to extend the version 1 of the
>     protocol to use 64-bit frame number.

...or simply use version 2 of the protocol.

  Paul

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[PATCH] xen: grant-table: Check truncation when giving access to a frame Julien Grall <julien.grall@arm.com> - 2016-06-13 13:00 +0200
  RE: [Xen-devel] [PATCH] xen: grant-table: Check truncation when  giving access to a frame Paul Durrant <Paul.Durrant@citrix.com> - 2016-06-13 14:30 +0200
    RE: [Xen-devel] [PATCH] xen: grant-table: Check truncation when  giving access to a frame Paul Durrant <Paul.Durrant@citrix.com> - 2016-06-13 14:50 +0200
      Re: [Xen-devel] [PATCH] xen: grant-table: Check truncation when  giving access to a frame Julien Grall <julien.grall@arm.com> - 2016-06-13 15:10 +0200
        RE: [Xen-devel] [PATCH] xen: grant-table: Check truncation when  giving access to a frame Paul Durrant <Paul.Durrant@citrix.com> - 2016-06-13 15:20 +0200
    Re: [Xen-devel] [PATCH] xen: grant-table: Check truncation when  giving access to a frame Julien Grall <julien.grall@arm.com> - 2016-06-13 14:50 +0200
      Re: [Xen-devel] [PATCH] xen: grant-table: Check truncation when  giving access to a frame Julien Grall <julien.grall@arm.com> - 2016-06-13 14:50 +0200

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