* [PATCH 3.14] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors
@ 2016-03-28 14:30 Chas Williams
2016-04-11 10:02 ` Luis Henriques
0 siblings, 1 reply; 2+ messages in thread
From: Chas Williams @ 2016-03-28 14:30 UTC (permalink / raw)
To: stable
Cc: Vitaly Kuznetsov, K. Y. Srinivasan, Greg Kroah-Hartman, Chas Williams
From: Vitaly Kuznetsov <vkuznets@redhat.com>
commit e513229b4c386e6c9f66298c13fde92f73e6e1ac upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ 3chas3@gmail.com: rebase to 3.14-stable ]
Signed-off-by: Chas Williams <3chas3@gmail.com>
---
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 077bb1b..e3b7341 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -31,6 +31,7 @@
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/completion.h>
+#include <linux/cpu.h>
#include <linux/hyperv.h>
#include <linux/kernel_stat.h>
#include <asm/hyperv.h>
@@ -689,6 +690,39 @@ static void vmbus_flow_handler(unsigned int irq, struct irq_desc *desc)
desc->action->handler(irq, desc->action->dev_id);
}
+#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.
*
@@ -747,6 +781,7 @@ static int vmbus_bus_init(int irq)
if (ret)
goto err_alloc;
+ hv_cpu_hotplug_quirk(true);
vmbus_request_offers();
return 0;
@@ -984,6 +1019,7 @@ static void __exit vmbus_exit(void)
bus_unregister(&hv_bus);
hv_cleanup();
acpi_bus_unregister_driver(&vmbus_acpi_driver);
+ hv_cpu_hotplug_quirk(false);
}
--
2.5.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 3.14] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors
2016-03-28 14:30 [PATCH 3.14] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors Chas Williams
@ 2016-04-11 10:02 ` Luis Henriques
0 siblings, 0 replies; 2+ messages in thread
From: Luis Henriques @ 2016-04-11 10:02 UTC (permalink / raw)
To: Chas Williams
Cc: stable, Vitaly Kuznetsov, K. Y. Srinivasan, Greg Kroah-Hartman
On Mon, Mar 28, 2016 at 10:30:41AM -0400, Chas Williams wrote:
> From: Vitaly Kuznetsov <vkuznets@redhat.com>
>
> commit e513229b4c386e6c9f66298c13fde92f73e6e1ac upstream.
>
> 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>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> [ 3chas3@gmail.com: rebase to 3.14-stable ]
Thanks, I'm also queuing this for the 3.16 kernel as well.
Cheers,
--
Lu�s
> Signed-off-by: Chas Williams <3chas3@gmail.com>
> ---
> 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 077bb1b..e3b7341 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -31,6 +31,7 @@
> #include <linux/slab.h>
> #include <linux/acpi.h>
> #include <linux/completion.h>
> +#include <linux/cpu.h>
> #include <linux/hyperv.h>
> #include <linux/kernel_stat.h>
> #include <asm/hyperv.h>
> @@ -689,6 +690,39 @@ static void vmbus_flow_handler(unsigned int irq, struct irq_desc *desc)
> desc->action->handler(irq, desc->action->dev_id);
> }
>
> +#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.
> *
> @@ -747,6 +781,7 @@ static int vmbus_bus_init(int irq)
> if (ret)
> goto err_alloc;
>
> + hv_cpu_hotplug_quirk(true);
> vmbus_request_offers();
>
> return 0;
> @@ -984,6 +1019,7 @@ static void __exit vmbus_exit(void)
> bus_unregister(&hv_bus);
> hv_cleanup();
> acpi_bus_unregister_driver(&vmbus_acpi_driver);
> + hv_cpu_hotplug_quirk(false);
> }
>
>
> --
> 2.5.0
>
> --
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