From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757656AbbAZXyB (ORCPT ); Mon, 26 Jan 2015 18:54:01 -0500 Received: from mail-bn1on0138.outbound.protection.outlook.com ([157.56.110.138]:62666 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757637AbbAZXx6 convert rfc822-to-8bit (ORCPT ); Mon, 26 Jan 2015 18:53:58 -0500 From: KY Srinivasan To: Greg Kroah-Hartman , Vitaly Kuznetsov CC: "devel@linuxdriverproject.org" , "Haiyang Zhang" , "linux-kernel@vger.kernel.org" , Dexuan Cui Subject: RE: [PATCH v3] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors Thread-Topic: [PATCH v3] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors Thread-Index: AQHQOVRHx2JpIeXls06rO07KVbUOyZzTA2yAgAAQdEA= Date: Mon, 26 Jan 2015 23:53:53 +0000 Message-ID: References: <1417431161-12845-1-git-send-email-vkuznets@redhat.com> <1421081411-5759-1-git-send-email-vkuznets@redhat.com> <20150125133659.GA21552@kroah.com> <87k309g729.fsf@vitty.brq.redhat.com> <20150126225429.GA17514@kroah.com> In-Reply-To: <20150126225429.GA17514@kroah.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [2001:4898:80e0:ee43::3] authentication-results: linuxfoundation.org; dkim=none (message not signed) header.d=none;linuxfoundation.org; dmarc=none action=none header.from=microsoft.com; x-dmarcaction-test: None x-microsoft-antispam: BCL:0;PCL:0;RULEID:(3005004);SRVR:BY2PR0301MB0775;UriScan:; x-exchange-antispam-report-test: UriScan:; x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:;SRVR:BY2PR0301MB0775; x-forefront-prvs: 0468FE4A2B x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(6009001)(164054003)(13464003)(377454003)(51704005)(76576001)(99286002)(33656002)(2900100001)(102836002)(93886004)(122556002)(40100003)(76176999)(46102003)(54356999)(50986999)(54606007)(106116001)(2656002)(87936001)(86362001)(19580395003)(19580405001)(74316001)(86612001)(92566002)(62966003)(77156002)(2950100001)(54206007)(3826002);DIR:OUT;SFP:1102;SCL:1;SRVR:BY2PR0301MB0775;H:BY2PR0301MB0711.namprd03.prod.outlook.com;FPR:;SPF:None;MLV:sfv;LANG:en; Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-MS-Exchange-CrossTenant-originalarrivaltime: 26 Jan 2015 23:53:53.3001 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY2PR0301MB0775 X-Microsoft-Antispam: BCL:0;PCL:0;RULEID:;SRVR:BY2PR0301MB0743; X-OriginatorOrg: microsoft.onmicrosoft.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Greg Kroah-Hartman [mailto:gregkh@linuxfoundation.org] > Sent: Monday, January 26, 2015 2:54 PM > To: Vitaly Kuznetsov > Cc: KY Srinivasan; devel@linuxdriverproject.org; Haiyang Zhang; linux- > kernel@vger.kernel.org; Dexuan Cui > Subject: Re: [PATCH v3] Drivers: hv: vmbus: prevent cpu offlining on newer > hypervisors > > On Mon, Jan 26, 2015 at 11:38:54AM +0100, Vitaly Kuznetsov wrote: > > Greg Kroah-Hartman writes: > > > > > On Mon, Jan 12, 2015 at 05:50:11PM +0100, Vitaly Kuznetsov wrote: > > >> When an SMP Hyper-V guest is running on top of 2012R2 Server and > > >> secondary cpus are sent offline (with echo 0 > > > >> /sys/devices/system/cpu/cpu$cpu/online) > > >> the system freeze is observed. This happens due to the fact that on > > >> newer hypervisors (Win8, WS2012R2, ...) vmbus channel handlers are > > >> distributed across all cpus (see init_vp_index() function in > > >> drivers/hv/channel_mgmt.c) and on cpu offlining nobody reassigns > > >> them to CPU0. Prevent cpu offlining when vmbus is loaded until the > issue is fixed host-side. > > >> > > >> This patch also disables hibernation but it is OK as it is also > > >> broken (MCE error is hit on resume). Suspend still works. > > >> > > >> Tested with WS2008R2 and WS2012R2. > > >> > > >> Signed-off-by: Vitaly Kuznetsov > > >> Signed-off-by: K. Y. Srinivasan > > >> --- > > >> Changes since v2: > > >> - repair the build when vmbus is builded as a module [Greg KH] by > saving > > >> current cpu_disable pointer to previous_cpu_disable and restoring it > on > > >> unload; > > >> - return -ENOSYS (same as native_cpu_disable when > !CONFIG_HOTPLUG_CPU) instead > > >> of -1 in hyperv_cpu_disable(). > > >> > > >> Changes since v1: > > >> - introduce hv_cpu_hotplug_quirk() function to not spread #ifdefs > > >> [Greg KH]; > > >> - add pr_notice() message "hv_vmbus: CPU offlining is not supported by > > >> hypervisor". > > >> --- > > >> drivers/hv/vmbus_drv.c | 36 > ++++++++++++++++++++++++++++++++++++ > > >> 1 file changed, 36 insertions(+) > > > > > > Doesn't apply to my char-misc-test branch at all :( > > > > Another mid-air collision with K.Y's "Drivers: hv: vmbus: Implement a > > clockevent device", please use the attached version. No functional > > changes are required, I just fixed the merge conflict (includes). > > > > Othere than that (and sorry for meddling), would it it be better if > > you switch to 'pull requests' workflow with K.Y? There is a lot of > > ongoing work in hyperv nowdays and such collisions seem otherwise > > inevitable ... > > This is a trivial number of patches for this subsystem, so no, a git workflow > isn't needed. But if KY would collect the patches up and send them to me for > all hyperv patches from now on, that would make these types of issues go > away, KY, can you do that from now on? Will do. Thanks, K. Y > > thanks, > > greg k-h