From d68d82afd4c88e25763b23cd9cd4974573a3706f Mon Sep 17 00:00:00 2001 From: Alex Nixon Date: Fri, 22 Aug 2008 11:52:15 +0100 Subject: [PATCH] xen: implement CPU hotplugging Note the changes from 2.6.18-xen CPU hotplugging: A vcpu_down request from the remote admin via Xenbus both hotunplugs the CPU, and disables it by removing it from the cpu_present map, and removing its entry in /sys. A vcpu_up request from the remote admin only re-enables the CPU, and does not immediately bring the CPU up. A udev event is emitted, which can be caught by the user if he wishes to automatically re-up CPUs when available, or implement a more complex policy. Signed-off-by: Alex Nixon Acked-by: Jeremy Fitzhardinge Signed-off-by: Ingo Molnar --- arch/x86/xen/smp.c | 60 ++++++++++++++++++++------ arch/x86/xen/spinlock.c | 5 +++ arch/x86/xen/time.c | 8 ++++ arch/x86/xen/xen-ops.h | 6 +++ drivers/xen/Makefile | 2 +- drivers/xen/cpu_hotplug.c | 90 +++++++++++++++++++++++++++++++++++++++ drivers/xen/events.c | 4 ++ 7 files changed, 162 insertions(+), 13 deletions(-) create mode 100644 drivers/xen/cpu_hotplug.c diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index baca7f2fbd8a..be5cbb2b7c60 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -11,8 +11,6 @@ * useful topology information for the kernel to make use of. As a * result, all CPUs are treated as if they're single-core and * single-threaded. - * - * This does not handle HOTPLUG_CPU yet. */ #include #include @@ -61,11 +59,12 @@ static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id) return IRQ_HANDLED; } -static __cpuinit void cpu_bringup_and_idle(void) +static __cpuinit void cpu_bringup(void) { int cpu = smp_processor_id(); cpu_init(); + touch_softlockup_watchdog(); preempt_disable(); xen_enable_sysenter(); @@ -86,6 +85,11 @@ static __cpuinit void cpu_bringup_and_idle(void) local_irq_enable(); wmb(); /* make sure everything is out */ +} + +static __cpuinit void cpu_bringup_and_idle(void) +{ + cpu_bringup(); cpu_idle(); } @@ -209,8 +213,6 @@ static void __init xen_smp_prepare_cpus(unsigned int max_cpus) cpu_set(cpu, cpu_present_map); } - - //init_xenbus_allowed_cpumask(); } static __cpuinit int @@ -278,12 +280,6 @@ static int __cpuinit xen_cpu_up(unsigned int cpu) struct task_struct *idle = idle_task(cpu); int rc; -#if 0 - rc = cpu_up_check(cpu); - if (rc) - return rc; -#endif - #ifdef CONFIG_X86_64 /* Allocate node local memory for AP pdas */ WARN_ON(cpu == 0); @@ -336,6 +332,42 @@ static void xen_smp_cpus_done(unsigned int max_cpus) { } +int xen_cpu_disable(void) +{ + unsigned int cpu = smp_processor_id(); + if (cpu == 0) + return -EBUSY; + + cpu_disable_common(); + + load_cr3(swapper_pg_dir); + return 0; +} + +void xen_cpu_die(unsigned int cpu) +{ + while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) { + current->state = TASK_UNINTERRUPTIBLE; + schedule_timeout(HZ/10); + } + unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL); + unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL); + unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL); + unbind_from_irqhandler(per_cpu(callfuncsingle_irq, cpu), NULL); + xen_uninit_lock_cpu(cpu); + xen_teardown_timer(cpu); + + if (num_online_cpus() == 1) + alternatives_smp_switch(0); +} + +void xen_play_dead(void) +{ + play_dead_common(); + HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL); + cpu_bringup(); +} + static void stop_self(void *v) { int cpu = smp_processor_id(); @@ -419,9 +451,13 @@ static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id) static const struct smp_ops xen_smp_ops __initdata = { .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu, .smp_prepare_cpus = xen_smp_prepare_cpus, - .cpu_up = xen_cpu_up, .smp_cpus_done = xen_smp_cpus_done, + .cpu_up = xen_cpu_up, + .cpu_die = xen_cpu_die, + .cpu_disable = xen_cpu_disable, + .play_dead = xen_play_dead, + .smp_send_stop = xen_smp_send_stop, .smp_send_reschedule = xen_smp_send_reschedule, diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index d072823bc06d..dd71e3a021cd 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -357,6 +357,11 @@ void __cpuinit xen_init_lock_cpu(int cpu) printk("cpu %d spinlock event irq %d\n", cpu, irq); } +void xen_uninit_lock_cpu(int cpu) +{ + unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL); +} + void __init xen_init_spinlocks(void) { pv_lock_ops.spin_is_locked = xen_spin_is_locked; diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index 20182d9072c4..004ba86326ae 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -450,6 +450,14 @@ void xen_setup_timer(int cpu) setup_runstate_info(cpu); } +void xen_teardown_timer(int cpu) +{ + struct clock_event_device *evt; + BUG_ON(cpu == 0); + evt = &per_cpu(xen_clock_events, cpu); + unbind_from_irqhandler(evt->irq, NULL); +} + void xen_setup_cpu_clockevents(void) { BUG_ON(preemptible()); diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h index 1e8bfdaa20d3..8dbd97fd7f18 100644 --- a/arch/x86/xen/xen-ops.h +++ b/arch/x86/xen/xen-ops.h @@ -34,6 +34,7 @@ void __init xen_build_dynamic_phys_to_machine(void); void xen_init_irq_ops(void); void xen_setup_timer(int cpu); +void xen_teardown_timer(int cpu); cycle_t xen_clocksource_read(void); void xen_setup_cpu_clockevents(void); unsigned long xen_tsc_khz(void); @@ -50,11 +51,16 @@ void xen_mark_init_mm_pinned(void); void __init xen_setup_vcpu_info_placement(void); +void xen_play_dead(void); +void xen_cpu_die(unsigned int cpu); +int xen_cpu_disable(void); + #ifdef CONFIG_SMP void xen_smp_init(void); void __init xen_init_spinlocks(void); __cpuinit void xen_init_lock_cpu(int cpu); +void xen_uninit_lock_cpu(int cpu); extern cpumask_t xen_cpu_initialized_map; #else diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index 363286c54290..f62d8df27696 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -1,4 +1,4 @@ -obj-y += grant-table.o features.o events.o manage.o +obj-y += grant-table.o features.o events.o manage.o cpu_hotplug.o obj-y += xenbus/ obj-$(CONFIG_XEN_XENCOMM) += xencomm.o obj-$(CONFIG_XEN_BALLOON) += balloon.o diff --git a/drivers/xen/cpu_hotplug.c b/drivers/xen/cpu_hotplug.c new file mode 100644 index 000000000000..1bc003536cdb --- /dev/null +++ b/drivers/xen/cpu_hotplug.c @@ -0,0 +1,90 @@ +#include + +#include + +#include +#include + +static void enable_hotplug_cpu(int cpu) +{ + if (!cpu_present(cpu)) + arch_register_cpu(cpu); + + cpu_set(cpu, cpu_present_map); +} + +static void disable_hotplug_cpu(int cpu) +{ + if (cpu_present(cpu)) + arch_unregister_cpu(cpu); + + cpu_clear(cpu, cpu_present_map); +} + +static void vcpu_hotplug(unsigned int cpu) +{ + int err; + char dir[32], state[32]; + + if (!cpu_possible(cpu)) + return; + + sprintf(dir, "cpu/%u", cpu); + err = xenbus_scanf(XBT_NIL, dir, "availability", "%s", state); + if (err != 1) { + printk(KERN_ERR "XENBUS: Unable to read cpu state\n"); + return; + } + + if (strcmp(state, "online") == 0) { + enable_hotplug_cpu(cpu); + } else if (strcmp(state, "offline") == 0) { + (void)cpu_down(cpu); + disable_hotplug_cpu(cpu); + } else { + printk(KERN_ERR "XENBUS: unknown state(%s) on CPU%d\n", + state, cpu); + } +} + +static void handle_vcpu_hotplug_event(struct xenbus_watch *watch, + const char **vec, unsigned int len) +{ + unsigned int cpu; + char *cpustr; + const char *node = vec[XS_WATCH_PATH]; + + cpustr = strstr(node, "cpu/"); + if (cpustr != NULL) { + sscanf(cpustr, "cpu/%u", &cpu); + vcpu_hotplug(cpu); + } +} + +static int setup_cpu_watcher(struct notifier_block *notifier, + unsigned long event, void *data) +{ + static struct xenbus_watch cpu_watch = { + .node = "cpu", + .callback = handle_vcpu_hotplug_event}; + + (void)register_xenbus_watch(&cpu_watch); + + return NOTIFY_DONE; +} + +static int __init setup_vcpu_hotplug_event(void) +{ + static struct notifier_block xsn_cpu = { + .notifier_call = setup_cpu_watcher }; + + if (!is_running_on_xen()) + return -ENODEV; + + register_xenstore_notifier(&xsn_cpu); + + return 0; +} + +arch_initcall(setup_vcpu_hotplug_event); + diff --git a/drivers/xen/events.c b/drivers/xen/events.c index b6c2b8f16bee..c3290bc186a0 100644 --- a/drivers/xen/events.c +++ b/drivers/xen/events.c @@ -360,6 +360,10 @@ static void unbind_from_irq(unsigned int irq) per_cpu(virq_to_irq, cpu_from_evtchn(evtchn)) [index_from_irq(irq)] = -1; break; + case IRQT_IPI: + per_cpu(ipi_to_irq, cpu_from_evtchn(evtchn)) + [index_from_irq(irq)] = -1; + break; default: break; }