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

[Julien Grall <julien.grall@xxxxxxx>]

Hi David,

On 13/06/16 11:57, David Vrabel wrote:
> On 13/06/16 11:50, Julien Grall wrote:
> > 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.
> In hindsight, we shouldn't have dropped the V2 support from Linux.
> Should we reinstate it?
What were the reasons to drop the v2 support from Linux? More 
importantly why people did choose to stay on v1?
Cheers,

--
Julien Grall

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