Dexuan Cui <decui@xxxxxxxxxxxxx> writes: >> -----Original Message----- >> From: devel [mailto:driverdev-devel-bounces@xxxxxxxxxxxxxxxxxxxxxx] On >> Behalf Of Greg Kroah-Hartman >> Sent: Thursday, November 27, 2014 11:03 AM >> To: Vitaly Kuznetsov >> Cc: devel@xxxxxxxxxxxxxxxxxxxxxx; Haiyang Zhang; linux- >> kernel@xxxxxxxxxxxxxxx >> 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@xxxxxxxxxx> >> > --- >> > 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? My idea was that eventually this function will start doing something real (e.g. switching channels to cpu0 if it doesn't happen fully host-side) so I called it with a general name 'hyperv_cpu_disable'. I'll try addressing our and Greg's comments in v2, thanks! > > Thanks, > -- Dexuan -- Vitaly _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
