| Message ID | 20230913163823.7880-36-james.morse@arm.com (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
| Series | ACPI/arm64: add support for virtual cpuhotplug | expand |
On Wed, 13 Sep 2023 16:38:23 +0000 James Morse <james.morse@arm.com> wrote: > The 'offline' file in sysfs shows all offline CPUs, including those > that aren't present. User-space is expected to remove not-present CPUs > from this list to learn which CPUs could be brought online. > > CPUs can be present but not-enabled. These CPUs can't be brought online > until the firmware policy changes, which comes with an ACPI notification > that will register the CPUs. > > With only the offline and present files, user-space is unable to > determine which CPUs it can try to bring online. Add a new CPU mask > that shows this based on all the registered CPUs. Bikeshed should be blue. Enabled is a really confusing name for this - to the extent that I'm not sure what it means. Assuming I have the sense right, how about the horrible onlineable or online_capable? > > Signed-off-by: James Morse <james.morse@arm.com> > --- > drivers/base/cpu.c | 10 ++++++++++ > include/linux/cpumask.h | 25 +++++++++++++++++++++++++ > kernel/cpu.c | 3 +++ > 3 files changed, 38 insertions(+) > > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > index c709747c4a18..a19a8be93102 100644 > --- a/drivers/base/cpu.c > +++ b/drivers/base/cpu.c > @@ -95,6 +95,7 @@ void unregister_cpu(struct cpu *cpu) > { > int logical_cpu = cpu->dev.id; > > + set_cpu_enabled(logical_cpu, false); > unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); > > device_unregister(&cpu->dev); > @@ -273,6 +274,13 @@ static ssize_t print_cpus_offline(struct device *dev, > } > static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); > > +static ssize_t print_cpus_enabled(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(cpu_enabled_mask)); > +} > +static DEVICE_ATTR(enabled, 0444, print_cpus_enabled, NULL); > + > static ssize_t print_cpus_isolated(struct device *dev, > struct device_attribute *attr, char *buf) > { > @@ -413,6 +421,7 @@ int register_cpu(struct cpu *cpu, int num) > register_cpu_under_node(num, cpu_to_node(num)); > dev_pm_qos_expose_latency_limit(&cpu->dev, > PM_QOS_RESUME_LATENCY_NO_CONSTRAINT); > + set_cpu_enabled(num, true); > > return 0; > } > @@ -494,6 +503,7 @@ static struct attribute *cpu_root_attrs[] = { > &cpu_attrs[2].attr.attr, > &dev_attr_kernel_max.attr, > &dev_attr_offline.attr, > + &dev_attr_enabled.attr, > &dev_attr_isolated.attr, > #ifdef CONFIG_NO_HZ_FULL > &dev_attr_nohz_full.attr, > diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h > index f10fb87d49db..a29ee03f13ff 100644 > --- a/include/linux/cpumask.h > +++ b/include/linux/cpumask.h > @@ -92,6 +92,7 @@ static inline void set_nr_cpu_ids(unsigned int nr) > * > * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable > * cpu_present_mask - has bit 'cpu' set iff cpu is populated > + * cpu_enabled_mask - has bit 'cpu' set iff cpu can be brought online > * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler > * cpu_active_mask - has bit 'cpu' set iff cpu available to migration > * > @@ -124,11 +125,13 @@ static inline void set_nr_cpu_ids(unsigned int nr) > > extern struct cpumask __cpu_possible_mask; > extern struct cpumask __cpu_online_mask; > +extern struct cpumask __cpu_enabled_mask; > extern struct cpumask __cpu_present_mask; > extern struct cpumask __cpu_active_mask; > extern struct cpumask __cpu_dying_mask; > #define cpu_possible_mask ((const struct cpumask *)&__cpu_possible_mask) > #define cpu_online_mask ((const struct cpumask *)&__cpu_online_mask) > +#define cpu_enabled_mask ((const struct cpumask *)&__cpu_enabled_mask) > #define cpu_present_mask ((const struct cpumask *)&__cpu_present_mask) > #define cpu_active_mask ((const struct cpumask *)&__cpu_active_mask) > #define cpu_dying_mask ((const struct cpumask *)&__cpu_dying_mask) > @@ -973,6 +976,7 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS); > #else > #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask) > #define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask) > +#define for_each_enabled_cpu(cpu) for_each_cpu((cpu), cpu_enabled_mask) > #define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask) > #endif > > @@ -995,6 +999,15 @@ set_cpu_possible(unsigned int cpu, bool possible) > cpumask_clear_cpu(cpu, &__cpu_possible_mask); > } > > +static inline void > +set_cpu_enabled(unsigned int cpu, bool can_be_onlined) > +{ > + if (can_be_onlined) > + cpumask_set_cpu(cpu, &__cpu_enabled_mask); > + else > + cpumask_clear_cpu(cpu, &__cpu_enabled_mask); > +} > + > static inline void > set_cpu_present(unsigned int cpu, bool present) > { > @@ -1074,6 +1087,7 @@ static __always_inline unsigned int num_online_cpus(void) > return raw_atomic_read(&__num_online_cpus); > } > #define num_possible_cpus() cpumask_weight(cpu_possible_mask) > +#define num_enabled_cpus() cpumask_weight(cpu_enabled_mask) > #define num_present_cpus() cpumask_weight(cpu_present_mask) > #define num_active_cpus() cpumask_weight(cpu_active_mask) > > @@ -1082,6 +1096,11 @@ static inline bool cpu_online(unsigned int cpu) > return cpumask_test_cpu(cpu, cpu_online_mask); > } > > +static inline bool cpu_enabled(unsigned int cpu) > +{ > + return cpumask_test_cpu(cpu, cpu_enabled_mask); > +} > + > static inline bool cpu_possible(unsigned int cpu) > { > return cpumask_test_cpu(cpu, cpu_possible_mask); > @@ -1106,6 +1125,7 @@ static inline bool cpu_dying(unsigned int cpu) > > #define num_online_cpus() 1U > #define num_possible_cpus() 1U > +#define num_enabled_cpus() 1U > #define num_present_cpus() 1U > #define num_active_cpus() 1U > > @@ -1119,6 +1139,11 @@ static inline bool cpu_possible(unsigned int cpu) > return cpu == 0; > } > > +static inline bool cpu_enabled(unsigned int cpu) > +{ > + return cpu == 0; > +} > + > static inline bool cpu_present(unsigned int cpu) > { > return cpu == 0; > diff --git a/kernel/cpu.c b/kernel/cpu.c > index 6de7c6bb74ee..2201a6a449b5 100644 > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -3101,6 +3101,9 @@ EXPORT_SYMBOL(__cpu_possible_mask); > struct cpumask __cpu_online_mask __read_mostly; > EXPORT_SYMBOL(__cpu_online_mask); > > +struct cpumask __cpu_enabled_mask __read_mostly; > +EXPORT_SYMBOL(__cpu_enabled_mask); > + > struct cpumask __cpu_present_mask __read_mostly; > EXPORT_SYMBOL(__cpu_present_mask); >
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index c709747c4a18..a19a8be93102 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -95,6 +95,7 @@ void unregister_cpu(struct cpu *cpu) { int logical_cpu = cpu->dev.id; + set_cpu_enabled(logical_cpu, false); unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); device_unregister(&cpu->dev); @@ -273,6 +274,13 @@ static ssize_t print_cpus_offline(struct device *dev, } static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); +static ssize_t print_cpus_enabled(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(cpu_enabled_mask)); +} +static DEVICE_ATTR(enabled, 0444, print_cpus_enabled, NULL); + static ssize_t print_cpus_isolated(struct device *dev, struct device_attribute *attr, char *buf) { @@ -413,6 +421,7 @@ int register_cpu(struct cpu *cpu, int num) register_cpu_under_node(num, cpu_to_node(num)); dev_pm_qos_expose_latency_limit(&cpu->dev, PM_QOS_RESUME_LATENCY_NO_CONSTRAINT); + set_cpu_enabled(num, true); return 0; } @@ -494,6 +503,7 @@ static struct attribute *cpu_root_attrs[] = { &cpu_attrs[2].attr.attr, &dev_attr_kernel_max.attr, &dev_attr_offline.attr, + &dev_attr_enabled.attr, &dev_attr_isolated.attr, #ifdef CONFIG_NO_HZ_FULL &dev_attr_nohz_full.attr, diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index f10fb87d49db..a29ee03f13ff 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -92,6 +92,7 @@ static inline void set_nr_cpu_ids(unsigned int nr) * * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable * cpu_present_mask - has bit 'cpu' set iff cpu is populated + * cpu_enabled_mask - has bit 'cpu' set iff cpu can be brought online * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler * cpu_active_mask - has bit 'cpu' set iff cpu available to migration * @@ -124,11 +125,13 @@ static inline void set_nr_cpu_ids(unsigned int nr) extern struct cpumask __cpu_possible_mask; extern struct cpumask __cpu_online_mask; +extern struct cpumask __cpu_enabled_mask; extern struct cpumask __cpu_present_mask; extern struct cpumask __cpu_active_mask; extern struct cpumask __cpu_dying_mask; #define cpu_possible_mask ((const struct cpumask *)&__cpu_possible_mask) #define cpu_online_mask ((const struct cpumask *)&__cpu_online_mask) +#define cpu_enabled_mask ((const struct cpumask *)&__cpu_enabled_mask) #define cpu_present_mask ((const struct cpumask *)&__cpu_present_mask) #define cpu_active_mask ((const struct cpumask *)&__cpu_active_mask) #define cpu_dying_mask ((const struct cpumask *)&__cpu_dying_mask) @@ -973,6 +976,7 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS); #else #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask) #define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask) +#define for_each_enabled_cpu(cpu) for_each_cpu((cpu), cpu_enabled_mask) #define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask) #endif @@ -995,6 +999,15 @@ set_cpu_possible(unsigned int cpu, bool possible) cpumask_clear_cpu(cpu, &__cpu_possible_mask); } +static inline void +set_cpu_enabled(unsigned int cpu, bool can_be_onlined) +{ + if (can_be_onlined) + cpumask_set_cpu(cpu, &__cpu_enabled_mask); + else + cpumask_clear_cpu(cpu, &__cpu_enabled_mask); +} + static inline void set_cpu_present(unsigned int cpu, bool present) { @@ -1074,6 +1087,7 @@ static __always_inline unsigned int num_online_cpus(void) return raw_atomic_read(&__num_online_cpus); } #define num_possible_cpus() cpumask_weight(cpu_possible_mask) +#define num_enabled_cpus() cpumask_weight(cpu_enabled_mask) #define num_present_cpus() cpumask_weight(cpu_present_mask) #define num_active_cpus() cpumask_weight(cpu_active_mask) @@ -1082,6 +1096,11 @@ static inline bool cpu_online(unsigned int cpu) return cpumask_test_cpu(cpu, cpu_online_mask); } +static inline bool cpu_enabled(unsigned int cpu) +{ + return cpumask_test_cpu(cpu, cpu_enabled_mask); +} + static inline bool cpu_possible(unsigned int cpu) { return cpumask_test_cpu(cpu, cpu_possible_mask); @@ -1106,6 +1125,7 @@ static inline bool cpu_dying(unsigned int cpu) #define num_online_cpus() 1U #define num_possible_cpus() 1U +#define num_enabled_cpus() 1U #define num_present_cpus() 1U #define num_active_cpus() 1U @@ -1119,6 +1139,11 @@ static inline bool cpu_possible(unsigned int cpu) return cpu == 0; } +static inline bool cpu_enabled(unsigned int cpu) +{ + return cpu == 0; +} + static inline bool cpu_present(unsigned int cpu) { return cpu == 0; diff --git a/kernel/cpu.c b/kernel/cpu.c index 6de7c6bb74ee..2201a6a449b5 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -3101,6 +3101,9 @@ EXPORT_SYMBOL(__cpu_possible_mask); struct cpumask __cpu_online_mask __read_mostly; EXPORT_SYMBOL(__cpu_online_mask); +struct cpumask __cpu_enabled_mask __read_mostly; +EXPORT_SYMBOL(__cpu_enabled_mask); + struct cpumask __cpu_present_mask __read_mostly; EXPORT_SYMBOL(__cpu_present_mask);
The 'offline' file in sysfs shows all offline CPUs, including those that aren't present. User-space is expected to remove not-present CPUs from this list to learn which CPUs could be brought online. CPUs can be present but not-enabled. These CPUs can't be brought online until the firmware policy changes, which comes with an ACPI notification that will register the CPUs. With only the offline and present files, user-space is unable to determine which CPUs it can try to bring online. Add a new CPU mask that shows this based on all the registered CPUs. Signed-off-by: James Morse <james.morse@arm.com> --- drivers/base/cpu.c | 10 ++++++++++ include/linux/cpumask.h | 25 +++++++++++++++++++++++++ kernel/cpu.c | 3 +++ 3 files changed, 38 insertions(+)