From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH v6 4/5] xen: introduce XENMEM_exchange_and_pin and XENMEM_unpin Date: Mon, 30 Sep 2013 13:42:56 +0100 Message-ID: <524971D0.5070804@cantab.net> References: <1380298560-29352-4-git-send-email-stefano.stabellini@eu.citrix.com> <5249462002000078000F7E33@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VQcoW-0002jA-5s for xen-devel@lists.xenproject.org; Mon, 30 Sep 2013 12:43:00 +0000 Received: by mail-wg0-f41.google.com with SMTP id l18so3427192wgh.2 for ; Mon, 30 Sep 2013 05:42:58 -0700 (PDT) In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Stefano Stabellini Cc: xen-devel , keir@xen.org, tim@xen.org, Ian.Campbell@citrix.com, Jan Beulich List-Id: xen-devel@lists.xenproject.org On 30/09/13 13:30, Stefano Stabellini wrote: > On Mon, 30 Sep 2013, Jan Beulich wrote: >>>>> On 27.09.13 at 18:15, Stefano Stabellini wrote: >>> Changes in v6: >>> - do not change error paths; >>> - crash the guest on pinning failure; >> >> Isn't that a little harsh? > > I agree that this is harsh, but it's quite difficult to undo the > page exchange that was previously done up to the point of failure. And a > pinning error can only be caused by a misbehaviour of the guest. > Overall this is a simple solution to a difficult problem. Do you need to undo the exchange if the pinning failed? Or could return an error status of "exchanged but not pinned" and have the guest do the right thing? David