From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754552AbbAYQQT (ORCPT ); Sun, 25 Jan 2015 11:16:19 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:55016 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754472AbbAYQQN (ORCPT ); Sun, 25 Jan 2015 11:16:13 -0500 Date: Sun, 25 Jan 2015 21:36:59 +0800 From: Greg Kroah-Hartman To: Vitaly Kuznetsov Cc: "K. Y. 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 Message-ID: <20150125133659.GA21552@kroah.com> References: <1417431161-12845-1-git-send-email-vkuznets@redhat.com> <1421081411-5759-1-git-send-email-vkuznets@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1421081411-5759-1-git-send-email-vkuznets@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 :(