Re: [Xen-devel] [PATCH] xen: grant-table: Simplify get_page_frame

[Julien Grall <julien.grall@xxxxxxx>]

Hi Jan,

On 09/15/2017 01:15 PM, Jan Beulich wrote:
> > > > On 14.09.17 at 18:49, <julien.grall@xxxxxxx> wrote:
> > get_page_from_gfn will be able to get reference on foreign page and as
> > per my understanding will allow to grant page on foreign memory.
> >
> > This was not allowed with a simple get_page(...) on the ARM
> > implementation (no sharing nor paging supprot) but is allowed on the x86
> > implementation due to get_page_from_gfn.
> >
> > On x86, foreign pages are currently only allowed for PVH dom0, so I
> > think it is not a big deal for now.
> >
> > On Arm, foreign pages can be present on any domain. So this patch would
> > permit grant on foreing pages.
> >
> > So I would like to check whether it would be valid to grant a mapping on
> > foreign pages?
> No, I don't think grants should be permitted for other domains'
> pages.
Which seems to match the PV behavior. I will update the patch to forbid 
foreign pages and use #ifdef.
Cheers,

--
Julien Grall

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