@@ -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 +672,39 @@ static void vmbus_isr(void)
tasklet_schedule(&msg_dpc);
}
+#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.
*
@@ -711,6 +745,7 @@ static int vmbus_bus_init(int irq)
if (ret)
goto err_alloc;
+ hv_cpu_hotplug_quirk(true);
vmbus_request_offers();
return 0;
@@ -964,6 +999,7 @@ static void __exit vmbus_exit(void)
bus_unregister(&hv_bus);
hv_cleanup();
acpi_bus_unregister_driver(&vmbus_acpi_driver);
+ hv_cpu_hotplug_quirk(false);
}
This is a note to let you know that I have just added a patch titled Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt19. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 1cd96098f5cbfed8449b5bfd7098312a37b9a94c Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov <vkuznets@redhat.com> Date: Fri, 27 Feb 2015 11:25:51 -0800 Subject: Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors 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> Cc: Chas Williams <3chas3@gmail.com> [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/hv/vmbus_drv.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) -- 2.7.4