LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Dexuan Cui <decui@microsoft.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "devel@linuxdriverproject.org" <devel@linuxdriverproject.org>,
	"Haiyang Zhang" <haiyangz@microsoft.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors
Date: Thu, 27 Nov 2014 03:24:48 +0000	[thread overview]
Message-ID: <F792CF86EFE20D4AB8064279AFBA51C613E63EAE@HKNPRD3002MB017.064d.mgd.msft.net> (raw)
In-Reply-To: <20141127030254.GA28028@kroah.com>

> -----Original Message-----
> From: devel [mailto:driverdev-devel-bounces@linuxdriverproject.org] On
> Behalf Of Greg Kroah-Hartman
> Sent: Thursday, November 27, 2014 11:03 AM
> To: Vitaly Kuznetsov
> Cc: devel@linuxdriverproject.org; Haiyang Zhang; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH] Drivers: hv: vmbus: prevent cpu offlining on newer
> hypervisors
> 
> On Wed, Nov 26, 2014 at 02:52:22PM +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>
> > ---
> >  drivers/hv/vmbus_drv.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> > index 4d6b269..9a82249 100644
> > --- a/drivers/hv/vmbus_drv.c
> > +++ b/drivers/hv/vmbus_drv.c
> > @@ -32,6 +32,7 @@
> >  #include <linux/completion.h>
> >  #include <linux/hyperv.h>
> >  #include <linux/kernel_stat.h>
> > +#include <linux/cpu.h>
> >  #include <asm/hyperv.h>
> >  #include <asm/hypervisor.h>
> >  #include <asm/mshyperv.h>
> > @@ -671,6 +672,13 @@ static void vmbus_isr(void)
> >  		tasklet_schedule(&msg_dpc);
> >  }
> >
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +static int hyperv_cpu_disable(void)
> > +{
> > +	return -1;
> > +}
> > +#endif
> > +
> >  /*
> >   * vmbus_bus_init -Main vmbus driver initialization routine.
> >   *
> > @@ -711,6 +719,12 @@ static int vmbus_bus_init(int irq)
> >  	if (ret)
> >  		goto err_alloc;
> >
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +	if ((vmbus_proto_version != VERSION_WS2008) &&
> > +	    (vmbus_proto_version != VERSION_WIN7))
> > +		smp_ops.cpu_disable = hyperv_cpu_disable;
> > +#endif
> > +
> >  	vmbus_request_offers();
> >
> >  	return 0;
> > @@ -964,6 +978,11 @@ static void __exit vmbus_exit(void)
> >  	bus_unregister(&hv_bus);
> >  	hv_cleanup();
> >  	acpi_bus_unregister_driver(&vmbus_acpi_driver);
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +	if ((vmbus_proto_version != VERSION_WS2008) &&
> > +	    (vmbus_proto_version != VERSION_WIN7))
> > +		smp_ops.cpu_disable = native_cpu_disable;
> > +#endif
> >  }
> 
> #ifdef in a .c file is not a good idea to do if at all possible, please
> only put this in one place, using a function call to "hide" the mess.
> 
> greg k-h

Hi Vitaly,
The idea of the patch is good to me.

I agree with Greg.
BTW, maybe hv_cpu_hotplug_quirk() is a better name?

Thanks,
-- Dexuan

  reply	other threads:[~2014-11-27  3:40 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-26 13:52 Vitaly Kuznetsov
2014-11-27  3:02 ` Greg Kroah-Hartman
2014-11-27  3:24   ` Dexuan Cui [this message]
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
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=F792CF86EFE20D4AB8064279AFBA51C613E63EAE@HKNPRD3002MB017.064d.mgd.msft.net \
    --to=decui@microsoft.com \
    --cc=devel@linuxdriverproject.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=haiyangz@microsoft.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=vkuznets@redhat.com \
    --subject='RE: [PATCH] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).