From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <ian.campbell@citrix.com>
Subject: Re: Question about mapping between domains
Date: Wed, 15 Jul 2015 13:00:58 +0100
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Keir Fraser <keir@xen.org>, Ian Jackson <ian.jackson@eu.citrix.com>, Oleksandr Dmytryshyn <oleksandr.dmytryshyn@globallogic.com>, Tim Deegan <tim@xen.org>, xen-devel <xen-devel@lists.xen.org>, Stefano Stabellini <stefano.stabellini@citrix.com>, Jan Beulich <jbeulich@suse.com>
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On Wed, 2015-07-15 at 12:51 +0100, Stefano Stabellini wrote:
> On Wed, 15 Jul 2015, Oleksandr Dmytryshyn wrote:
> > Hi, Ian. Thank You for the response.
> > 
> > > Look at how the balloon driver does it, the hypercalls you want are
> > > XENMEM_(increase|decrease)_reservation.
> > I'll try to use those hypercalls.
> 
> In the modern Linux kernels, you just need to call gnttab_alloc_pages
> (see drivers/xen/grant-table.c:gnttab_alloc_pages).

The problem here is to grant map pages to fill and existing buffer which
is already allocated/supplied elswhere (in the GPU stack I suppose).