From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756139AbbALSyU (ORCPT ); Mon, 12 Jan 2015 13:54:20 -0500 Received: from mail-bl2on0106.outbound.protection.outlook.com ([65.55.169.106]:27648 "EHLO na01-bl2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753854AbbALSyQ convert rfc822-to-8bit (ORCPT ); Mon, 12 Jan 2015 13:54:16 -0500 From: KY Srinivasan To: Vitaly Kuznetsov , "devel@linuxdriverproject.org" CC: Haiyang Zhang , Greg Kroah-Hartman , "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: AQHQLofcx2JpIeXls06rO07KVbUOyZy803uA Date: Mon, 12 Jan 2015 18:54:13 +0000 Message-ID: References: <1417431161-12845-1-git-send-email-vkuznets@redhat.com> <1421081411-5759-1-git-send-email-vkuznets@redhat.com> In-Reply-To: <1421081411-5759-1-git-send-email-vkuznets@redhat.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [2001:4898:80e0:ee43::2] authentication-results: spf=none (sender IP is ) smtp.mailfrom=kys@microsoft.com; x-dmarcaction-test: None x-microsoft-antispam: BCL:0;PCL:0;RULEID:(3005003);SRVR:BY2PR0301MB0775; x-exchange-antispam-report-test: UriScan:; x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:;SRVR:BY2PR0301MB0775; x-forefront-prvs: 0454444834 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(6009001)(13464003)(377454003)(51704005)(199003)(189002)(40100003)(19580405001)(19580395003)(99286002)(2656002)(50986999)(92566002)(76176999)(2501002)(97736003)(106116001)(64706001)(74316001)(102836002)(46102003)(86362001)(575784001)(62966003)(2900100001)(77156002)(2950100001)(54606007)(87936001)(105586002)(54356999)(68736005)(33656002)(101416001)(76576001)(3826002);DIR:OUT;SFP:1102;SCL:1;SRVR:BY2PR0301MB0775;H:BY2PR0301MB0711.namprd03.prod.outlook.com;FPR:;SPF:None;MLV:sfv;PTR:InfoNoRecords;A:1;MX:1;LANG:en; Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-OriginatorOrg: microsoft.onmicrosoft.com X-MS-Exchange-CrossTenant-originalarrivaltime: 12 Jan 2015 18:54:13.5161 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY2PR0301MB0775 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com] > Sent: Monday, January 12, 2015 8:50 AM > To: KY Srinivasan; devel@linuxdriverproject.org > Cc: Haiyang Zhang; Greg Kroah-Hartman; linux-kernel@vger.kernel.org; > Dexuan Cui > Subject: [PATCH v3] Drivers: hv: vmbus: prevent cpu offlining on newer > hypervisors > > 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 Thank you. 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(+) > > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c > index 4d6b269..233da0b 100644 > --- a/drivers/hv/vmbus_drv.c > +++ b/drivers/hv/vmbus_drv.c > @@ -32,6 +32,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -671,6 +672,39 @@ static void vmbus_isr(void) > tasklet_schedule(&msg_dpc); > } > > +#ifdef CONFIG_HOTPLUG_CPU > +static int hyperv_cpu_disable(void) > +{ > + return -ENOSYS; > +} > + > +static void hv_cpu_hotplug_quirk(bool vmbus_loaded) > +{ > + static void *previous_cpu_disable; > + > + /* > + * Offlining a CPU when running on newer hypervisors (WS2012R2, > Win8, > + * ...) is not supported at this moment as channel interrupts are > + * distributed across all of them. > + */ > + > + if ((vmbus_proto_version == VERSION_WS2008) || > + (vmbus_proto_version == VERSION_WIN7)) > + return; > + > + if (vmbus_loaded) { > + previous_cpu_disable = smp_ops.cpu_disable; > + smp_ops.cpu_disable = hyperv_cpu_disable; > + pr_notice("CPU offlining is not supported by hypervisor\n"); > + } else if (previous_cpu_disable) > + smp_ops.cpu_disable = previous_cpu_disable; > +} > +#else > +static void hv_cpu_hotplug_quirk(bool vmbus_loaded) > +{ > +} > +#endif > + > /* > * vmbus_bus_init -Main vmbus driver initialization routine. > * > @@ -711,6 +745,7 @@ static int vmbus_bus_init(int irq) > if (ret) > goto err_alloc; > > + hv_cpu_hotplug_quirk(true); > vmbus_request_offers(); > > return 0; > @@ -964,6 +999,7 @@ static void __exit vmbus_exit(void) > bus_unregister(&hv_bus); > hv_cleanup(); > acpi_bus_unregister_driver(&vmbus_acpi_driver); > + hv_cpu_hotplug_quirk(false); > } > > > -- > 1.9.3