From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH v2] x86/PV: fix unintended dependency of m2p-strict mode on migration-v2 Date: Tue, 2 Feb 2016 15:18:04 +0000 Message-ID: <56B0C8AC.5090708@citrix.com> References: <56B0D5CF02000078000CD941@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aQciW-0003qW-J8 for xen-devel@lists.xenproject.org; Tue, 02 Feb 2016 15:18:08 +0000 In-Reply-To: <56B0D5CF02000078000CD941@prv-mh.provo.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich , xen-devel Cc: Keir Fraser List-Id: xen-devel@lists.xenproject.org On 02/02/16 15:14, Jan Beulich wrote: > This went unnoticed until a backport of this to an older Xen got used, > causing migration of guests enabling this VM assist to fail, because > page table pinning there precedes vCPU context loading, and hence L4 > tables get initialized for the wrong mode. Fix this by post-processing > L4 tables when setting the intended VM assist flags for the guest. > > Note that this leaves in place a dependency on vCPU 0 getting its guest > context restored first, but afaict the logic here is not the only thing > depending on that. > > Signed-off-by: Jan Beulich > --- > v2: Avoid entering the loop when strict mode was already before, which > in turn requires deferring the assignment to d->vm_assist until > after the loop. Reviewed-by: Andrew Cooper