From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH v2 COLOPre 03/13] libxc/restore: zero ioreq page only one time Date: Mon, 8 Jun 2015 11:15:33 +0100 Message-ID: <55756B45.8020708@citrix.com> References: <1433734997-26570-1-git-send-email-yanghy@cn.fujitsu.com> <1433734997-26570-4-git-send-email-yanghy@cn.fujitsu.com> <55756468.4090500@citrix.com> <55756757.7020900@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <55756757.7020900@cn.fujitsu.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: Yang Hongyang , xen-devel@lists.xen.org Cc: wei.liu2@citrix.com, ian.campbell@citrix.com, wency@cn.fujitsu.com, guijianfeng@cn.fujitsu.com, yunhong.jiang@intel.com, eddie.dong@intel.com, rshriram@cs.ubc.ca, ian.jackson@eu.citrix.com List-Id: xen-devel@lists.xenproject.org On 08/06/15 10:58, Yang Hongyang wrote: > > > On 06/08/2015 05:46 PM, Andrew Cooper wrote: >> On 08/06/15 04:43, Yang Hongyang wrote: >>> ioreq page contains evtchn which will be set when we resume the >>> secondary vm the first time. The hypervisor will check if the >>> evtchn is corrupted, so we cannot zero the ioreq page more >>> than one time. >>> >>> The ioreq->state is always STATE_IOREQ_NONE after the vm is >>> suspended, so it is OK if we only zero it one time. >>> >>> Signed-off-by: Yang Hongyang >>> Signed-off-by: Wen congyang >>> CC: Andrew Cooper >> >> The issue here is that we are running the restore algorithm over a >> domain which has already been running in Xen for a while. This is a >> brand new usecase, as far as I am aware. > > Exactly. > >> >> Does the qemu process associated with this domain get frozen while the >> secondary is being reset, or does the process get destroyed and >> recreated. > > What do you mean by reset? do you mean secondary is suspended at > checkpoint? Well - at the point that the buffered records are being processed, we are in the process of resetting the state of the secondary to match the primary. ~Andrew > >> >> I have a gut feeling that it would be safer to clear all of the page >> other than the event channel, but that depends on exactly what else is >> going on. We absolutely don't want to do is have an update to this page >> from the primary with an in-progress IOREQ. >> >> ~Andrew >> >>> --- >>> tools/libxc/xc_sr_restore_x86_hvm.c | 3 ++- >>> 1 file changed, 2 insertions(+), 1 deletion(-) >>> >>> diff --git a/tools/libxc/xc_sr_restore_x86_hvm.c >>> b/tools/libxc/xc_sr_restore_x86_hvm.c >>> index 6f5af0e..06177e0 100644 >>> --- a/tools/libxc/xc_sr_restore_x86_hvm.c >>> +++ b/tools/libxc/xc_sr_restore_x86_hvm.c >>> @@ -78,7 +78,8 @@ static int handle_hvm_params(struct xc_sr_context >>> *ctx, >>> break; >>> case HVM_PARAM_IOREQ_PFN: >>> case HVM_PARAM_BUFIOREQ_PFN: >>> - xc_clear_domain_page(xch, ctx->domid, entry->value); >>> + if ( !ctx->restore.buffer_all_records ) >>> + xc_clear_domain_page(xch, ctx->domid, entry->value); >>> break; >>> } >>> >> >> . >> >