Re: [Xen-devel] [PATCH for-4.6] xen/mm: populate_physmap: validate correctly the gfn for direct mapped domain

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Aug 11, 2015 at 06:41:28PM +0100, Julien Grall wrote:
> Direct mapped domain has already the memory allocated 1:1, so we are
> directly using the gfn as mfn to map the RAM in the guest.
> 
> While we are validating that the page associated to the first mfn belongs to
> the domain, the subsequent MFN are not validated when the extent_order
> is > 0.
> 
> This may result to map memory region (MMIO, RAM) which doesn't belong to the
> domain.
> 
> Although, only DOM0 on ARM is using a direct memory mapped. So it
> doesn't affect any guest (at least on the upstream version) or even x86.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> 
> ---
> Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Keir Fraser <keir@xxxxxxx>
> Cc: Tim Deegan <tim@xxxxxxx>
> 
>     This patch is a candidate for Xen 4.6 and backport to Xen 4.5 (and
>     maybe 4.4).
> 

Fine by me in principle for this patch to go in 4.6.

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