From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752955AbaLAKwv (ORCPT ); Mon, 1 Dec 2014 05:52:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34599 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752646AbaLAKwu (ORCPT ); Mon, 1 Dec 2014 05:52:50 -0500 From: Vitaly Kuznetsov To: "K. Y. Srinivasan" , Haiyang Zhang Cc: devel@linuxdriverproject.org, Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Dexuan Cui Subject: [PATCH v2] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors Date: Mon, 1 Dec 2014 11:52:41 +0100 Message-Id: <1417431161-12845-1-git-send-email-vkuznets@redhat.com> In-Reply-To: <1417009942-10216-1-git-send-email-vkuznets@redhat.com> References: <1417009942-10216-1-git-send-email-vkuznets@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 4d6b269..2e6b38e 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 +672,36 @@ static void vmbus_isr(void) tasklet_schedule(&msg_dpc); } +#ifdef CONFIG_HOTPLUG_CPU +static int hyperv_cpu_disable(void) +{ + return -1; +} + +static void hv_cpu_hotplug_quirk(bool vmbus_loaded) +{ + /* + * 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) { + smp_ops.cpu_disable = hyperv_cpu_disable; + pr_notice("CPU offlining is not supported by hypervisor"); + } else + smp_ops.cpu_disable = native_cpu_disable; +} +#else +static void hv_cpu_hotplug_quirk(bool vmbus_loaded) +{ +} +#endif + /* * vmbus_bus_init -Main vmbus driver initialization routine. * @@ -711,6 +742,7 @@ static int vmbus_bus_init(int irq) if (ret) goto err_alloc; + hv_cpu_hotplug_quirk(true); vmbus_request_offers(); return 0; @@ -964,6 +996,7 @@ 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