From mboxrd@z Thu Jan  1 00:00:00 1970
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH RFC 4/4] xen: arch-specific hooks for
	domain_soft_reset()
Date: Mon, 22 Jun 2015 11:44:18 +0200
Message-ID: <87616g9ix9.fsf@vitty.brq.redhat.com>
References: <1433338522-8422-1-git-send-email-vkuznets@redhat.com>
	<1433338522-8422-5-git-send-email-vkuznets@redhat.com>
	<20150604141953.GH74656@deinos.phlegethon.org>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
Received: from mail6.bemta3.messagelabs.com ([195.245.230.39])
	by lists.xen.org with esmtp (Exim 4.72)
	(envelope-from <vkuznets@redhat.com>) id 1Z6yHE-000323-5l
	for xen-devel@lists.xenproject.org; Mon, 22 Jun 2015 09:44:28 +0000
In-Reply-To: <20150604141953.GH74656@deinos.phlegethon.org> (Tim Deegan's
	message of "Thu, 4 Jun 2015 15:19:53 +0100")
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Tim Deegan <tim@xen.org>
Cc: Wei Liu <wei.liu2@citrix.com>, Andrew Jones <drjones@redhat.com>, Julien Grall <julien.grall@linaro.org>, Keir Fraser <keir@xen.org>, Ian Campbell <ian.campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, Olaf Hering <olaf@aepfle.de>, David Vrabel <david.vrabel@citrix.com>, Jan Beulich <jbeulich@suse.com>, xen-devel@lists.xenproject.org, Daniel De Graaf <dgdegra@tycho.nsa.gov>
List-Id: xen-devel@lists.xenproject.org

Tim Deegan <tim@xen.org> writes:

> At 15:35 +0200 on 03 Jun (1433345722), Vitaly Kuznetsov wrote:
>> x86-specific hook cleans up the pirq-emuirq mappings and replaces the
>> shared_info frame with an empty page to support subsequent
>> XENMAPSPACE_shared_info call.
>
> That's a bit roundabout.  I think we might be better off allocating a
> new shared-info page and abandoning the old one as an ordinary guest
> RAM page.
>

I've tried looking into such approach and there is an issue: shared_info
page is being allocated from Xen heap and in case it's built with
CONFIG_SEPARATE_XENHEAP we can't just reassign the page to the domain's
pagelist or we'll open a possibility for a domain to move itself
entirely to Xen's heap by e.g looping over all its gfns, doing
XENMAPSPACE_shared_info and perforting soft reset.

-- 
  Vitaly