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Date: Wed, 26 Nov 2014 14:52:22 +0100 From: Vitaly Kuznetsov <vkuznets@...hat.com> To: "K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, devel@...uxdriverproject.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, linux-kernel@...r.kernel.org, Dexuan Cui <decui@...rosoft.com> Subject: [PATCH] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors 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@...hat.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 } -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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