From d5de8841355a48f7f634a04507185eaf1f9755e3 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 23 Jul 2008 13:28:58 -0700 Subject: x86: split spinlock implementations out into their own files ftrace requires certain low-level code, like spinlocks and timestamps, to be compiled without -pg in order to avoid infinite recursion. This patch splits out the core paravirt spinlocks and the Xen spinlocks into separate files which can be compiled without -pg. Also do xen/time.c while we're about it. As a result, we can now use ftrace within a Xen domain. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Ingo Molnar --- arch/x86/xen/smp.c | 167 ----------------------------------------------------- 1 file changed, 167 deletions(-) (limited to 'arch/x86/xen/smp.c') diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index d8faf79a0a1d..baca7f2fbd8a 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -15,7 +15,6 @@ * This does not handle HOTPLUG_CPU yet. */ #include -#include #include #include @@ -36,8 +35,6 @@ #include "xen-ops.h" #include "mmu.h" -static void __cpuinit xen_init_lock_cpu(int cpu); - cpumask_t xen_cpu_initialized_map; static DEFINE_PER_CPU(int, resched_irq); @@ -419,170 +416,6 @@ static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id) return IRQ_HANDLED; } -struct xen_spinlock { - unsigned char lock; /* 0 -> free; 1 -> locked */ - unsigned short spinners; /* count of waiting cpus */ -}; - -static int xen_spin_is_locked(struct raw_spinlock *lock) -{ - struct xen_spinlock *xl = (struct xen_spinlock *)lock; - - return xl->lock != 0; -} - -static int xen_spin_is_contended(struct raw_spinlock *lock) -{ - struct xen_spinlock *xl = (struct xen_spinlock *)lock; - - /* Not strictly true; this is only the count of contended - lock-takers entering the slow path. */ - return xl->spinners != 0; -} - -static int xen_spin_trylock(struct raw_spinlock *lock) -{ - struct xen_spinlock *xl = (struct xen_spinlock *)lock; - u8 old = 1; - - asm("xchgb %b0,%1" - : "+q" (old), "+m" (xl->lock) : : "memory"); - - return old == 0; -} - -static DEFINE_PER_CPU(int, lock_kicker_irq) = -1; -static DEFINE_PER_CPU(struct xen_spinlock *, lock_spinners); - -static inline void spinning_lock(struct xen_spinlock *xl) -{ - __get_cpu_var(lock_spinners) = xl; - wmb(); /* set lock of interest before count */ - asm(LOCK_PREFIX " incw %0" - : "+m" (xl->spinners) : : "memory"); -} - -static inline void unspinning_lock(struct xen_spinlock *xl) -{ - asm(LOCK_PREFIX " decw %0" - : "+m" (xl->spinners) : : "memory"); - wmb(); /* decrement count before clearing lock */ - __get_cpu_var(lock_spinners) = NULL; -} - -static noinline int xen_spin_lock_slow(struct raw_spinlock *lock) -{ - struct xen_spinlock *xl = (struct xen_spinlock *)lock; - int irq = __get_cpu_var(lock_kicker_irq); - int ret; - - /* If kicker interrupts not initialized yet, just spin */ - if (irq == -1) - return 0; - - /* announce we're spinning */ - spinning_lock(xl); - - /* clear pending */ - xen_clear_irq_pending(irq); - - /* check again make sure it didn't become free while - we weren't looking */ - ret = xen_spin_trylock(lock); - if (ret) - goto out; - - /* block until irq becomes pending */ - xen_poll_irq(irq); - kstat_this_cpu.irqs[irq]++; - -out: - unspinning_lock(xl); - return ret; -} - -static void xen_spin_lock(struct raw_spinlock *lock) -{ - struct xen_spinlock *xl = (struct xen_spinlock *)lock; - int timeout; - u8 oldval; - - do { - timeout = 1 << 10; - - asm("1: xchgb %1,%0\n" - " testb %1,%1\n" - " jz 3f\n" - "2: rep;nop\n" - " cmpb $0,%0\n" - " je 1b\n" - " dec %2\n" - " jnz 2b\n" - "3:\n" - : "+m" (xl->lock), "=q" (oldval), "+r" (timeout) - : "1" (1) - : "memory"); - - } while (unlikely(oldval != 0 && !xen_spin_lock_slow(lock))); -} - -static noinline void xen_spin_unlock_slow(struct xen_spinlock *xl) -{ - int cpu; - - for_each_online_cpu(cpu) { - /* XXX should mix up next cpu selection */ - if (per_cpu(lock_spinners, cpu) == xl) { - xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR); - break; - } - } -} - -static void xen_spin_unlock(struct raw_spinlock *lock) -{ - struct xen_spinlock *xl = (struct xen_spinlock *)lock; - - smp_wmb(); /* make sure no writes get moved after unlock */ - xl->lock = 0; /* release lock */ - - /* make sure unlock happens before kick */ - barrier(); - - if (unlikely(xl->spinners)) - xen_spin_unlock_slow(xl); -} - -static __cpuinit void xen_init_lock_cpu(int cpu) -{ - int irq; - const char *name; - - name = kasprintf(GFP_KERNEL, "spinlock%d", cpu); - irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR, - cpu, - xen_reschedule_interrupt, - IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, - name, - NULL); - - if (irq >= 0) { - disable_irq(irq); /* make sure it's never delivered */ - per_cpu(lock_kicker_irq, cpu) = irq; - } - - printk("cpu %d spinlock event irq %d\n", cpu, irq); -} - -static void __init xen_init_spinlocks(void) -{ - pv_lock_ops.spin_is_locked = xen_spin_is_locked; - pv_lock_ops.spin_is_contended = xen_spin_is_contended; - pv_lock_ops.spin_lock = xen_spin_lock; - pv_lock_ops.spin_trylock = xen_spin_trylock; - pv_lock_ops.spin_unlock = xen_spin_unlock; -} - 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, -- cgit v1.2.3 From d68d82afd4c88e25763b23cd9cd4974573a3706f Mon Sep 17 00:00:00 2001 From: Alex Nixon Date: Fri, 22 Aug 2008 11:52:15 +0100 Subject: 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 (limited to 'arch/x86/xen/smp.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; } -- cgit v1.2.3 From 2737146b3aa2cf8b5d5ae87a18c49fe1c374528b Mon Sep 17 00:00:00 2001 From: Alex Nixon Date: Mon, 8 Sep 2008 13:43:33 +0100 Subject: x86, xen: fix build when !CONFIG_HOTPLUG_CPU Signed-off-by: Alex Nixon Acked-by: Jeremy Fitzhardinge Signed-off-by: Ingo Molnar --- arch/x86/xen/smp.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'arch/x86/xen/smp.c') diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index be5cbb2b7c60..bf51a466d62c 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -332,6 +332,7 @@ static void xen_smp_cpus_done(unsigned int max_cpus) { } +#ifdef CONFIG_HOTPLUG_CPU int xen_cpu_disable(void) { unsigned int cpu = smp_processor_id(); @@ -368,6 +369,23 @@ void xen_play_dead(void) cpu_bringup(); } +#else /* !CONFIG_HOTPLUG_CPU */ +int xen_cpu_disable(void) +{ + return -ENOSYS; +} + +void xen_cpu_die(unsigned int cpu) +{ + BUG(); +} + +void xen_play_dead(void) +{ + BUG(); +} + +#endif static void stop_self(void *v) { int cpu = smp_processor_id(); -- cgit v1.2.3 From 26fd10517e810dd59ea050b052de24a75ee6dc07 Mon Sep 17 00:00:00 2001 From: Alex Nixon Date: Mon, 8 Sep 2008 13:43:34 +0100 Subject: xen: make CPU hotplug functions static There's no need for these functions to be accessed from outside of xen/smp.c Signed-off-by: Alex Nixon Acked-by: Jeremy Fitzhardinge Signed-off-by: Ingo Molnar --- arch/x86/xen/smp.c | 12 ++++++------ arch/x86/xen/xen-ops.h | 4 ---- 2 files changed, 6 insertions(+), 10 deletions(-) (limited to 'arch/x86/xen/smp.c') diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index bf51a466d62c..d77da613b1d2 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -333,7 +333,7 @@ static void xen_smp_cpus_done(unsigned int max_cpus) } #ifdef CONFIG_HOTPLUG_CPU -int xen_cpu_disable(void) +static int xen_cpu_disable(void) { unsigned int cpu = smp_processor_id(); if (cpu == 0) @@ -345,7 +345,7 @@ int xen_cpu_disable(void) return 0; } -void xen_cpu_die(unsigned int cpu) +static void xen_cpu_die(unsigned int cpu) { while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) { current->state = TASK_UNINTERRUPTIBLE; @@ -362,7 +362,7 @@ void xen_cpu_die(unsigned int cpu) alternatives_smp_switch(0); } -void xen_play_dead(void) +static void xen_play_dead(void) { play_dead_common(); HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL); @@ -370,17 +370,17 @@ void xen_play_dead(void) } #else /* !CONFIG_HOTPLUG_CPU */ -int xen_cpu_disable(void) +static int xen_cpu_disable(void) { return -ENOSYS; } -void xen_cpu_die(unsigned int cpu) +static void xen_cpu_die(unsigned int cpu) { BUG(); } -void xen_play_dead(void) +static void xen_play_dead(void) { BUG(); } diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h index 8dbd97fd7f18..d7422dc2a55c 100644 --- a/arch/x86/xen/xen-ops.h +++ b/arch/x86/xen/xen-ops.h @@ -51,10 +51,6 @@ 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); -- cgit v1.2.3