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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>,
	devel@linuxdriverproject.org,
	Haiyang Zhang <haiyangz@microsoft.com>,
	linux-kernel@vger.kernel.org, Dexuan Cui <decui@microsoft.com>
Subject: Re: [PATCH v3] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors
Date: Sun, 25 Jan 2015 21:36:59 +0800	[thread overview]
Message-ID: <20150125133659.GA21552@kroah.com> (raw)
In-Reply-To: <1421081411-5759-1-git-send-email-vkuznets@redhat.com>

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 <vkuznets@redhat.com>
> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> ---
> 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 :(

  parent reply	other threads:[~2015-01-25 16:16 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-26 13:52 [PATCH] " Vitaly Kuznetsov
2014-11-27  3:02 ` Greg Kroah-Hartman
2014-11-27  3:24   ` Dexuan Cui
2014-11-27  9:52     ` Vitaly Kuznetsov
2014-12-01 10:52 ` [PATCH v2] " Vitaly Kuznetsov
2014-12-01 11:12   ` Dexuan Cui
2015-01-09 20:57   ` Greg Kroah-Hartman
2015-01-12 16:50   ` [PATCH v3] " Vitaly Kuznetsov
2015-01-12 18:54     ` KY Srinivasan
2015-01-25 13:36     ` Greg Kroah-Hartman [this message]
2015-01-26 10:38       ` Vitaly Kuznetsov
2015-01-26 16:11         ` KY Srinivasan
2015-01-26 22:54         ` Greg Kroah-Hartman
2015-01-26 23:53           ` KY Srinivasan

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