> -----Original Message----- > From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx] > Sent: Monday, January 12, 2015 8:50 AM > To: KY Srinivasan; devel@xxxxxxxxxxxxxxxxxxxxxx > Cc: Haiyang Zhang; Greg Kroah-Hartman; linux-kernel@xxxxxxxxxxxxxxx; > Dexuan Cui > Subject: [PATCH v3] 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@xxxxxxxxxx> Thank you. Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > --- > 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(+) > > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c > index 4d6b269..233da0b 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 +672,39 @@ 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); > } > > > -- > 1.9.3 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
