From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [PATCH 1/5] xen/netback: Use xenballooned pages for
	comms
Date: Mon, 24 Oct 2011 17:40:44 -0400
Message-ID: <20111024214044.GJ2441@phenom.dumpdata.com>
References: <1318969583-23902-1-git-send-email-dgdegra@tycho.nsa.gov>
	<1318969583-23902-2-git-send-email-dgdegra@tycho.nsa.gov>
	<1319015064.3385.80.camel@zakaz.uk.xensource.com>
	<4E9EE659.8090600@tycho.nsa.gov>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Return-path: <xen-devel-bounces@lists.xensource.com>
Content-Disposition: inline
In-Reply-To: <4E9EE659.8090600@tycho.nsa.gov>
List-Unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xensource.com>
List-Help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-Subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
Sender: xen-devel-bounces@lists.xensource.com
Errors-To: xen-devel-bounces@lists.xensource.com
To: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, Ian Campbell <Ian.Campbell@citrix.com>, David Vrabel <david.vrabel@citrix.com>
List-Id: xen-devel@lists.xenproject.org

> (Will move to commit message). In PV guests, it is sufficient to only
> reserve kernel address space for grant mappings because Xen modifies the
> mappings directly. HVM guests require that Xen modify the GFN-to-MFN
> mapping, so the pages being remapped must already be allocated. Pages

By allocated you mean the populate_physmap hypercall must happen before
the grant operations are done?

(When I see allocated I think alloc_page, which I believe is _not_ what
you were saying).

> obtained from alloc_xenballooned_pages have valid GFNs not currently
> mapped to an MFN, so are available to be used in grant mappings.
>