From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Deegan Subject: Re: [PATCH 3 of 7] Use a reserved pfn in the guest address space to store mem event rings Date: Thu, 1 Mar 2012 17:32:26 +0000 Message-ID: <20120301173226.GA49888@ocelot.phlegethon.org> References: <0e79f8005b6b68e84a0f.1329977108@xdev.gridcentric.ca> <1330434093.31269.150.camel@zakaz.uk.xensource.com> <5e43716b77c694ad491d82077777b705.squirrel@webmail.lagarcavilla.org> <1330588073.10008.113.camel@dagon.hellion.org.uk> <20120301151733.GA48103@ocelot.phlegethon.org> <5386f6530efff6dfa885941add2f1efc.squirrel@webmail.lagarcavilla.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <5386f6530efff6dfa885941add2f1efc.squirrel@webmail.lagarcavilla.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Andres Lagar-Cavilla Cc: "olaf@aepfle.de" , "xen-devel@lists.xensource.com" , Ian Campbell , "andres@gridcentric.ca" , Ian Jackson , "keir.xen@gmail.com" , "adin@gridcentric.ca" List-Id: xen-devel@lists.xenproject.org At 08:30 -0800 on 01 Mar (1330590637), Andres Lagar-Cavilla wrote: > > At 07:47 +0000 on 01 Mar (1330588073), Ian Campbell wrote: > >> > > Is there no scope for making these pages owned by the domain but not > >> > > actually part of the P2M? We can cope with that for other types of > >> magic > >> > > page, can't we? > > > > It would need a new operation to map the ring into the tool that uses > > it; normal map-foreign-page ops need a GFN. > > Actually, confirmed: we can call xc_domain_decrease_reservation on the > ring after it's mapped by the helper. Guest won't get at it. Nothing > breaks. But that would only work if: - the helper always attaches before the guest gets to run; and - you never need to restart the helper. Tim.