| Message ID | 1376497228-20543-5-git-send-email-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 14 Aug 2013, Mark Rutland wrote: > This patch adds the basic infrastructure necessary to support > CPU_HOTPLUG on arm64, based on the arm implementation. Actual hotplug > support will depend on an implementation's smp_operations (e.g. PSCI). > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Nicolas Pitre <nico@linaro.org> > --- > arch/arm64/Kconfig | 7 ++++ > arch/arm64/include/asm/irq.h | 1 + > arch/arm64/include/asm/smp.h | 14 +++++++ > arch/arm64/kernel/cputable.c | 2 +- > arch/arm64/kernel/irq.c | 61 ++++++++++++++++++++++++++++ > arch/arm64/kernel/process.c | 7 ++++ > arch/arm64/kernel/smp.c | 97 ++++++++++++++++++++++++++++++++++++++++++++ > 7 files changed, 188 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 9737e97..5ce4ccb 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -158,6 +158,13 @@ config NR_CPUS > default "8" if ARCH_XGENE > default "4" > > +config HOTPLUG_CPU > + bool "Support for hot-pluggable CPUs" > + depends on SMP > + help > + Say Y here to experiment with turning CPUs off and on. CPUs > + can be controlled through /sys/devices/system/cpu. > + > source kernel/Kconfig.preempt > > config HZ > diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h > index 0332fc0..e1f7ecd 100644 > --- a/arch/arm64/include/asm/irq.h > +++ b/arch/arm64/include/asm/irq.h > @@ -4,6 +4,7 @@ > #include <asm-generic/irq.h> > > extern void (*handle_arch_irq)(struct pt_regs *); > +extern void migrate_irqs(void); > extern void set_handle_irq(void (*handle_irq)(struct pt_regs *)); > > #endif > diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h > index 831090a..d2ef02e 100644 > --- a/arch/arm64/include/asm/smp.h > +++ b/arch/arm64/include/asm/smp.h > @@ -67,6 +67,11 @@ extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); > > struct device_node; > > +extern int __cpu_disable(void); > + > +extern void __cpu_die(unsigned int cpu); > +extern void cpu_die(void); > + > /** > * struct smp_operations - Callback operations for hotplugging CPUs. > * > @@ -80,6 +85,11 @@ struct device_node; > * @cpu_boot: Boots a cpu into the kernel. > * @cpu_postboot: Optionally, perform any post-boot cleanup or necesary > * synchronisation. Called from the cpu being booted. > + * @cpu_disable: Prepares a cpu to die. May fail for some mechanism-specific > + * reason, which will cause the hot unplug to be aborted. Called > + * from the cpu to be killed. > + * @cpu_die: Makes the a leave the kernel. Must not fail. Called from the > + * cpu being killed. > */ > struct smp_operations { > const char *name; > @@ -87,6 +97,10 @@ struct smp_operations { > int (*cpu_prepare)(unsigned int); > int (*cpu_boot)(unsigned int); > void (*cpu_postboot)(void); > +#ifdef CONFIG_HOTPLUG_CPU > + int (*cpu_disable)(unsigned int cpu); > + void (*cpu_die)(unsigned int cpu); > +#endif > }; > > extern const struct smp_operations smp_spin_table_ops; > diff --git a/arch/arm64/kernel/cputable.c b/arch/arm64/kernel/cputable.c > index 63cfc4a..fd3993c 100644 > --- a/arch/arm64/kernel/cputable.c > +++ b/arch/arm64/kernel/cputable.c > @@ -22,7 +22,7 @@ > > extern unsigned long __cpu_setup(void); > > -struct cpu_info __initdata cpu_table[] = { > +struct cpu_info cpu_table[] = { > { > .cpu_id_val = 0x000f0000, > .cpu_id_mask = 0x000f0000, > diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c > index ecb3354..473e5db 100644 > --- a/arch/arm64/kernel/irq.c > +++ b/arch/arm64/kernel/irq.c > @@ -81,3 +81,64 @@ void __init init_IRQ(void) > if (!handle_arch_irq) > panic("No interrupt controller found."); > } > + > +#ifdef CONFIG_HOTPLUG_CPU > +static bool migrate_one_irq(struct irq_desc *desc) > +{ > + struct irq_data *d = irq_desc_get_irq_data(desc); > + const struct cpumask *affinity = d->affinity; > + struct irq_chip *c; > + bool ret = false; > + > + /* > + * If this is a per-CPU interrupt, or the affinity does not > + * include this CPU, then we have nothing to do. > + */ > + if (irqd_is_per_cpu(d) || !cpumask_test_cpu(smp_processor_id(), affinity)) > + return false; > + > + if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) { > + affinity = cpu_online_mask; > + ret = true; > + } > + > + c = irq_data_get_irq_chip(d); > + if (!c->irq_set_affinity) > + pr_debug("IRQ%u: unable to set affinity\n", d->irq); > + else if (c->irq_set_affinity(d, affinity, true) == IRQ_SET_MASK_OK && ret) > + cpumask_copy(d->affinity, affinity); > + > + return ret; > +} > + > +/* > + * The current CPU has been marked offline. Migrate IRQs off this CPU. > + * If the affinity settings do not allow other CPUs, force them onto any > + * available CPU. > + * > + * Note: we must iterate over all IRQs, whether they have an attached > + * action structure or not, as we need to get chained interrupts too. > + */ > +void migrate_irqs(void) > +{ > + unsigned int i; > + struct irq_desc *desc; > + unsigned long flags; > + > + local_irq_save(flags); > + > + for_each_irq_desc(i, desc) { > + bool affinity_broken; > + > + raw_spin_lock(&desc->lock); > + affinity_broken = migrate_one_irq(desc); > + raw_spin_unlock(&desc->lock); > + > + if (affinity_broken) > + pr_warn_ratelimited("IRQ%u no longer affine to CPU%u\n", > + i, smp_processor_id()); > + } > + > + local_irq_restore(flags); > +} > +#endif /* CONFIG_HOTPLUG_CPU */ > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index 57fb55c..19f17ec 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -102,6 +102,13 @@ void arch_cpu_idle(void) > local_irq_enable(); > } > > +#ifdef CONFIG_HOTPLUG_CPU > +void arch_cpu_idle_dead(void) > +{ > + cpu_die(); > +} > +#endif > + > void machine_shutdown(void) > { > #ifdef CONFIG_SMP > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index f6ce2ae..51c1acd 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -168,6 +168,103 @@ asmlinkage void secondary_start_kernel(void) > cpu_startup_entry(CPUHP_ONLINE); > } > > +#ifdef CONFIG_HOTPLUG_CPU > +static int op_cpu_disable(unsigned int cpu) > +{ > + /* > + * If we don't have a cpu_die method, abort before we reach the point > + * of no return. CPU0 may not have an smp_ops, so test for it. > + */ > + if (!smp_ops[cpu] || !smp_ops[cpu]->cpu_die) > + return -EOPNOTSUPP; > + > + /* > + * We may need to abort a hot unplug for some other mechanism-specific > + * reason. > + */ > + if (smp_ops[cpu]->cpu_disable) > + return smp_ops[cpu]->cpu_disable(cpu); > + > + return 0; > +} > + > +/* > + * __cpu_disable runs on the processor to be shutdown. > + */ > +int __cpu_disable(void) > +{ > + unsigned int cpu = smp_processor_id(); > + int ret; > + > + ret = op_cpu_disable(cpu); > + if (ret) > + return ret; > + > + /* > + * Take this CPU offline. Once we clear this, we can't return, > + * and we must not schedule until we're ready to give up the cpu. > + */ > + set_cpu_online(cpu, false); > + > + /* > + * OK - migrate IRQs away from this CPU > + */ > + migrate_irqs(); > + > + /* > + * Remove this CPU from the vm mask set of all processes. > + */ > + clear_tasks_mm_cpumask(cpu); > + > + return 0; > +} > + > +static DECLARE_COMPLETION(cpu_died); > + > +/* > + * called on the thread which is asking for a CPU to be shutdown - > + * waits until shutdown has completed, or it is timed out. > + */ > +void __cpu_die(unsigned int cpu) > +{ > + if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) { > + pr_crit("CPU%u: cpu didn't die\n", cpu); > + return; > + } > + pr_notice("CPU%u: shutdown\n", cpu); > +} > + > +/* > + * Called from the idle thread for the CPU which has been shutdown. > + * > + * Note that we disable IRQs here, but do not re-enable them > + * before returning to the caller. This is also the behaviour > + * of the other hotplug-cpu capable cores, so presumably coming > + * out of idle fixes this. > + */ > +void __ref cpu_die(void) > +{ > + unsigned int cpu = smp_processor_id(); > + > + idle_task_exit(); > + > + local_irq_disable(); > + mb(); > + > + /* Tell __cpu_die() that this CPU is now safe to dispose of */ > + complete(&cpu_died); > + > + /* > + * Actually shutdown the CPU. This must never fail. The specific hotplug > + * mechanism must perform all required cache maintenance to ensure that > + * no dirty lines are lost in the process of shutting down the CPU. > + */ > + smp_ops[cpu]->cpu_die(cpu); > + > + BUG(); > +} > +#endif > + > void __init smp_cpus_done(unsigned int max_cpus) > { > unsigned long bogosum = loops_per_jiffy * num_online_cpus(); > -- > 1.8.1.1 >
On Wednesday 14 August 2013 12:20 PM, Mark Rutland wrote: > This patch adds the basic infrastructure necessary to support > CPU_HOTPLUG on arm64, based on the arm implementation. Actual hotplug > support will depend on an implementation's smp_operations (e.g. PSCI). > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > --- > arch/arm64/Kconfig | 7 ++++ > arch/arm64/include/asm/irq.h | 1 + > arch/arm64/include/asm/smp.h | 14 +++++++ > arch/arm64/kernel/cputable.c | 2 +- > arch/arm64/kernel/irq.c | 61 ++++++++++++++++++++++++++++ > arch/arm64/kernel/process.c | 7 ++++ > arch/arm64/kernel/smp.c | 97 ++++++++++++++++++++++++++++++++++++++++++++ > 7 files changed, 188 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 9737e97..5ce4ccb 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -158,6 +158,13 @@ config NR_CPUS > default "8" if ARCH_XGENE > default "4" > > +config HOTPLUG_CPU > + bool "Support for hot-pluggable CPUs" > + depends on SMP > + help > + Say Y here to experiment with turning CPUs off and on. CPUs > + can be controlled through /sys/devices/system/cpu. > + > source kernel/Kconfig.preempt > > config HZ > diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h > index 0332fc0..e1f7ecd 100644 > --- a/arch/arm64/include/asm/irq.h > +++ b/arch/arm64/include/asm/irq.h > @@ -4,6 +4,7 @@ > #include <asm-generic/irq.h> > > extern void (*handle_arch_irq)(struct pt_regs *); > +extern void migrate_irqs(void); > extern void set_handle_irq(void (*handle_irq)(struct pt_regs *)); > > #endif > diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h > index 831090a..d2ef02e 100644 > --- a/arch/arm64/include/asm/smp.h > +++ b/arch/arm64/include/asm/smp.h > @@ -67,6 +67,11 @@ extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); > > struct device_node; > > +extern int __cpu_disable(void); > + > +extern void __cpu_die(unsigned int cpu); > +extern void cpu_die(void); > + > /** > * struct smp_operations - Callback operations for hotplugging CPUs. > * > @@ -80,6 +85,11 @@ struct device_node; > * @cpu_boot: Boots a cpu into the kernel. > * @cpu_postboot: Optionally, perform any post-boot cleanup or necesary > * synchronisation. Called from the cpu being booted. > + * @cpu_disable: Prepares a cpu to die. May fail for some mechanism-specific > + * reason, which will cause the hot unplug to be aborted. Called > + * from the cpu to be killed. > + * @cpu_die: Makes the a leave the kernel. Must not fail. Called from the > + * cpu being killed. > */ > struct smp_operations { > const char *name; > @@ -87,6 +97,10 @@ struct smp_operations { > int (*cpu_prepare)(unsigned int); > int (*cpu_boot)(unsigned int); > void (*cpu_postboot)(void); > +#ifdef CONFIG_HOTPLUG_CPU > + int (*cpu_disable)(unsigned int cpu); > + void (*cpu_die)(unsigned int cpu); > +#endif > }; > > extern const struct smp_operations smp_spin_table_ops; > diff --git a/arch/arm64/kernel/cputable.c b/arch/arm64/kernel/cputable.c > index 63cfc4a..fd3993c 100644 > --- a/arch/arm64/kernel/cputable.c > +++ b/arch/arm64/kernel/cputable.c > @@ -22,7 +22,7 @@ > > extern unsigned long __cpu_setup(void); > > -struct cpu_info __initdata cpu_table[] = { > +struct cpu_info cpu_table[] = { > { > .cpu_id_val = 0x000f0000, > .cpu_id_mask = 0x000f0000, > diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c > index ecb3354..473e5db 100644 > --- a/arch/arm64/kernel/irq.c > +++ b/arch/arm64/kernel/irq.c > @@ -81,3 +81,64 @@ void __init init_IRQ(void) > if (!handle_arch_irq) > panic("No interrupt controller found."); > } > + > +#ifdef CONFIG_HOTPLUG_CPU > +static bool migrate_one_irq(struct irq_desc *desc) > +{ > + struct irq_data *d = irq_desc_get_irq_data(desc); > + const struct cpumask *affinity = d->affinity; > + struct irq_chip *c; > + bool ret = false; > + > + /* > + * If this is a per-CPU interrupt, or the affinity does not > + * include this CPU, then we have nothing to do. > + */ > + if (irqd_is_per_cpu(d) || !cpumask_test_cpu(smp_processor_id(), affinity)) > + return false; > + > + if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) { > + affinity = cpu_online_mask; > + ret = true; > + } > + > + c = irq_data_get_irq_chip(d); > + if (!c->irq_set_affinity) > + pr_debug("IRQ%u: unable to set affinity\n", d->irq); > + else if (c->irq_set_affinity(d, affinity, true) == IRQ_SET_MASK_OK && ret) > + cpumask_copy(d->affinity, affinity); > + > + return ret; > +} > + > +/* > + * The current CPU has been marked offline. Migrate IRQs off this CPU. > + * If the affinity settings do not allow other CPUs, force them onto any > + * available CPU. > + * > + * Note: we must iterate over all IRQs, whether they have an attached > + * action structure or not, as we need to get chained interrupts too. > + */ > +void migrate_irqs(void) > +{ > + unsigned int i; > + struct irq_desc *desc; > + unsigned long flags; > + > + local_irq_save(flags); > + > + for_each_irq_desc(i, desc) { > + bool affinity_broken; > + > + raw_spin_lock(&desc->lock); > + affinity_broken = migrate_one_irq(desc); > + raw_spin_unlock(&desc->lock); > + > + if (affinity_broken) > + pr_warn_ratelimited("IRQ%u no longer affine to CPU%u\n", > + i, smp_processor_id()); > + } > + > + local_irq_restore(flags); > +} > +#endif /* CONFIG_HOTPLUG_CPU */ > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index 57fb55c..19f17ec 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -102,6 +102,13 @@ void arch_cpu_idle(void) > local_irq_enable(); > } > > +#ifdef CONFIG_HOTPLUG_CPU > +void arch_cpu_idle_dead(void) > +{ > + cpu_die(); > +} > +#endif > + > void machine_shutdown(void) > { > #ifdef CONFIG_SMP > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index f6ce2ae..51c1acd 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -168,6 +168,103 @@ asmlinkage void secondary_start_kernel(void) > cpu_startup_entry(CPUHP_ONLINE); > } > > +#ifdef CONFIG_HOTPLUG_CPU > +static int op_cpu_disable(unsigned int cpu) > +{ > + /* > + * If we don't have a cpu_die method, abort before we reach the point > + * of no return. CPU0 may not have an smp_ops, so test for it. > + */ > + if (!smp_ops[cpu] || !smp_ops[cpu]->cpu_die) > + return -EOPNOTSUPP; > + > + /* > + * We may need to abort a hot unplug for some other mechanism-specific > + * reason. > + */ > + if (smp_ops[cpu]->cpu_disable) > + return smp_ops[cpu]->cpu_disable(cpu); > + > + return 0; > +} > + > +/* > + * __cpu_disable runs on the processor to be shutdown. > + */ > +int __cpu_disable(void) > +{ > + unsigned int cpu = smp_processor_id(); > + int ret; > + > + ret = op_cpu_disable(cpu); > + if (ret) > + return ret; > + > + /* > + * Take this CPU offline. Once we clear this, we can't return, > + * and we must not schedule until we're ready to give up the cpu. > + */ > + set_cpu_online(cpu, false); > + > + /* > + * OK - migrate IRQs away from this CPU > + */ > + migrate_irqs(); > + > + /* > + * Remove this CPU from the vm mask set of all processes. > + */ > + clear_tasks_mm_cpumask(cpu); > + > + return 0; > +} > + > +static DECLARE_COMPLETION(cpu_died); > + > +/* > + * called on the thread which is asking for a CPU to be shutdown - > + * waits until shutdown has completed, or it is timed out. > + */ > +void __cpu_die(unsigned int cpu) > +{ > + if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) { > + pr_crit("CPU%u: cpu didn't die\n", cpu); > + return; > + } > + pr_notice("CPU%u: shutdown\n", cpu); > +} > + > +/* > + * Called from the idle thread for the CPU which has been shutdown. > + * > + * Note that we disable IRQs here, but do not re-enable them > + * before returning to the caller. This is also the behaviour > + * of the other hotplug-cpu capable cores, so presumably coming > + * out of idle fixes this. > + */ > +void __ref cpu_die(void) > +{ > + unsigned int cpu = smp_processor_id(); > + > + idle_task_exit(); > + > + local_irq_disable(); > + mb(); > + > + /* Tell __cpu_die() that this CPU is now safe to dispose of */ > + complete(&cpu_died); > + > + /* > + * Actually shutdown the CPU. This must never fail. The specific hotplug > + * mechanism must perform all required cache maintenance to ensure that > + * no dirty lines are lost in the process of shutting down the CPU. > + */ > + smp_ops[cpu]->cpu_die(cpu); > + > + BUG(); > +} > +#endif > + > void __init smp_cpus_done(unsigned int max_cpus) > { > unsigned long bogosum = loops_per_jiffy * num_online_cpus(); > Above code looks like direct re-use from arm32 bit port. I don't know whether its worth trouble to abstract but at least code looks pretty same. Other than the patch looks fine. Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 9737e97..5ce4ccb 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -158,6 +158,13 @@ config NR_CPUS default "8" if ARCH_XGENE default "4" +config HOTPLUG_CPU + bool "Support for hot-pluggable CPUs" + depends on SMP + help + Say Y here to experiment with turning CPUs off and on. CPUs + can be controlled through /sys/devices/system/cpu. + source kernel/Kconfig.preempt config HZ diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h index 0332fc0..e1f7ecd 100644 --- a/arch/arm64/include/asm/irq.h +++ b/arch/arm64/include/asm/irq.h @@ -4,6 +4,7 @@ #include <asm-generic/irq.h> extern void (*handle_arch_irq)(struct pt_regs *); +extern void migrate_irqs(void); extern void set_handle_irq(void (*handle_irq)(struct pt_regs *)); #endif diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h index 831090a..d2ef02e 100644 --- a/arch/arm64/include/asm/smp.h +++ b/arch/arm64/include/asm/smp.h @@ -67,6 +67,11 @@ extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); struct device_node; +extern int __cpu_disable(void); + +extern void __cpu_die(unsigned int cpu); +extern void cpu_die(void); + /** * struct smp_operations - Callback operations for hotplugging CPUs. * @@ -80,6 +85,11 @@ struct device_node; * @cpu_boot: Boots a cpu into the kernel. * @cpu_postboot: Optionally, perform any post-boot cleanup or necesary * synchronisation. Called from the cpu being booted. + * @cpu_disable: Prepares a cpu to die. May fail for some mechanism-specific + * reason, which will cause the hot unplug to be aborted. Called + * from the cpu to be killed. + * @cpu_die: Makes the a leave the kernel. Must not fail. Called from the + * cpu being killed. */ struct smp_operations { const char *name; @@ -87,6 +97,10 @@ struct smp_operations { int (*cpu_prepare)(unsigned int); int (*cpu_boot)(unsigned int); void (*cpu_postboot)(void); +#ifdef CONFIG_HOTPLUG_CPU + int (*cpu_disable)(unsigned int cpu); + void (*cpu_die)(unsigned int cpu); +#endif }; extern const struct smp_operations smp_spin_table_ops; diff --git a/arch/arm64/kernel/cputable.c b/arch/arm64/kernel/cputable.c index 63cfc4a..fd3993c 100644 --- a/arch/arm64/kernel/cputable.c +++ b/arch/arm64/kernel/cputable.c @@ -22,7 +22,7 @@ extern unsigned long __cpu_setup(void); -struct cpu_info __initdata cpu_table[] = { +struct cpu_info cpu_table[] = { { .cpu_id_val = 0x000f0000, .cpu_id_mask = 0x000f0000, diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c index ecb3354..473e5db 100644 --- a/arch/arm64/kernel/irq.c +++ b/arch/arm64/kernel/irq.c @@ -81,3 +81,64 @@ void __init init_IRQ(void) if (!handle_arch_irq) panic("No interrupt controller found."); } + +#ifdef CONFIG_HOTPLUG_CPU +static bool migrate_one_irq(struct irq_desc *desc) +{ + struct irq_data *d = irq_desc_get_irq_data(desc); + const struct cpumask *affinity = d->affinity; + struct irq_chip *c; + bool ret = false; + + /* + * If this is a per-CPU interrupt, or the affinity does not + * include this CPU, then we have nothing to do. + */ + if (irqd_is_per_cpu(d) || !cpumask_test_cpu(smp_processor_id(), affinity)) + return false; + + if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) { + affinity = cpu_online_mask; + ret = true; + } + + c = irq_data_get_irq_chip(d); + if (!c->irq_set_affinity) + pr_debug("IRQ%u: unable to set affinity\n", d->irq); + else if (c->irq_set_affinity(d, affinity, true) == IRQ_SET_MASK_OK && ret) + cpumask_copy(d->affinity, affinity); + + return ret; +} + +/* + * The current CPU has been marked offline. Migrate IRQs off this CPU. + * If the affinity settings do not allow other CPUs, force them onto any + * available CPU. + * + * Note: we must iterate over all IRQs, whether they have an attached + * action structure or not, as we need to get chained interrupts too. + */ +void migrate_irqs(void) +{ + unsigned int i; + struct irq_desc *desc; + unsigned long flags; + + local_irq_save(flags); + + for_each_irq_desc(i, desc) { + bool affinity_broken; + + raw_spin_lock(&desc->lock); + affinity_broken = migrate_one_irq(desc); + raw_spin_unlock(&desc->lock); + + if (affinity_broken) + pr_warn_ratelimited("IRQ%u no longer affine to CPU%u\n", + i, smp_processor_id()); + } + + local_irq_restore(flags); +} +#endif /* CONFIG_HOTPLUG_CPU */ diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 57fb55c..19f17ec 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -102,6 +102,13 @@ void arch_cpu_idle(void) local_irq_enable(); } +#ifdef CONFIG_HOTPLUG_CPU +void arch_cpu_idle_dead(void) +{ + cpu_die(); +} +#endif + void machine_shutdown(void) { #ifdef CONFIG_SMP diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index f6ce2ae..51c1acd 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -168,6 +168,103 @@ asmlinkage void secondary_start_kernel(void) cpu_startup_entry(CPUHP_ONLINE); } +#ifdef CONFIG_HOTPLUG_CPU +static int op_cpu_disable(unsigned int cpu) +{ + /* + * If we don't have a cpu_die method, abort before we reach the point + * of no return. CPU0 may not have an smp_ops, so test for it. + */ + if (!smp_ops[cpu] || !smp_ops[cpu]->cpu_die) + return -EOPNOTSUPP; + + /* + * We may need to abort a hot unplug for some other mechanism-specific + * reason. + */ + if (smp_ops[cpu]->cpu_disable) + return smp_ops[cpu]->cpu_disable(cpu); + + return 0; +} + +/* + * __cpu_disable runs on the processor to be shutdown. + */ +int __cpu_disable(void) +{ + unsigned int cpu = smp_processor_id(); + int ret; + + ret = op_cpu_disable(cpu); + if (ret) + return ret; + + /* + * Take this CPU offline. Once we clear this, we can't return, + * and we must not schedule until we're ready to give up the cpu. + */ + set_cpu_online(cpu, false); + + /* + * OK - migrate IRQs away from this CPU + */ + migrate_irqs(); + + /* + * Remove this CPU from the vm mask set of all processes. + */ + clear_tasks_mm_cpumask(cpu); + + return 0; +} + +static DECLARE_COMPLETION(cpu_died); + +/* + * called on the thread which is asking for a CPU to be shutdown - + * waits until shutdown has completed, or it is timed out. + */ +void __cpu_die(unsigned int cpu) +{ + if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) { + pr_crit("CPU%u: cpu didn't die\n", cpu); + return; + } + pr_notice("CPU%u: shutdown\n", cpu); +} + +/* + * Called from the idle thread for the CPU which has been shutdown. + * + * Note that we disable IRQs here, but do not re-enable them + * before returning to the caller. This is also the behaviour + * of the other hotplug-cpu capable cores, so presumably coming + * out of idle fixes this. + */ +void __ref cpu_die(void) +{ + unsigned int cpu = smp_processor_id(); + + idle_task_exit(); + + local_irq_disable(); + mb(); + + /* Tell __cpu_die() that this CPU is now safe to dispose of */ + complete(&cpu_died); + + /* + * Actually shutdown the CPU. This must never fail. The specific hotplug + * mechanism must perform all required cache maintenance to ensure that + * no dirty lines are lost in the process of shutting down the CPU. + */ + smp_ops[cpu]->cpu_die(cpu); + + BUG(); +} +#endif + void __init smp_cpus_done(unsigned int max_cpus) { unsigned long bogosum = loops_per_jiffy * num_online_cpus();
This patch adds the basic infrastructure necessary to support CPU_HOTPLUG on arm64, based on the arm implementation. Actual hotplug support will depend on an implementation's smp_operations (e.g. PSCI). Signed-off-by: Mark Rutland <mark.rutland@arm.com> --- arch/arm64/Kconfig | 7 ++++ arch/arm64/include/asm/irq.h | 1 + arch/arm64/include/asm/smp.h | 14 +++++++ arch/arm64/kernel/cputable.c | 2 +- arch/arm64/kernel/irq.c | 61 ++++++++++++++++++++++++++++ arch/arm64/kernel/process.c | 7 ++++ arch/arm64/kernel/smp.c | 97 ++++++++++++++++++++++++++++++++++++++++++++ 7 files changed, 188 insertions(+), 1 deletion(-)