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linux-stable/include/linux/cpu.h
Linus Torvalds 6f49693a6c Updates for the CPU hotplug core: 
- Support partial SMT enablement.
 
     So far the sysfs SMT control only allows to toggle between SMT on and
     off. That's sufficient for x86 which usually has at max two threads
     except for the Xeon PHI platform which has four threads per core.
 
     Though PowerPC has up to 16 threads per core and so far it's only
     possible to control the number of enabled threads per core via a
     command line option. There is some way to control this at runtime, but
     that lacks enforcement and the usability is awkward.
 
     This update expands the sysfs interface and the core infrastructure to
     accept numerical values so PowerPC can build SMT runtime control for
     partial SMT enablement on top.
 
     The core support has also been provided to the PowerPC maintainers who
     added the PowerPC related changes on top.
 
   - Minor cleanups and documentation updates.
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Merge tag 'smp-core-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull CPU hotplug updates from Thomas Gleixner:
 "Updates for the CPU hotplug core:

   - Support partial SMT enablement.

     So far the sysfs SMT control only allows to toggle between SMT on
     and off. That's sufficient for x86 which usually has at max two
     threads except for the Xeon PHI platform which has four threads per
     core

     Though PowerPC has up to 16 threads per core and so far it's only
     possible to control the number of enabled threads per core via a
     command line option. There is some way to control this at runtime,
     but that lacks enforcement and the usability is awkward

     This update expands the sysfs interface and the core infrastructure
     to accept numerical values so PowerPC can build SMT runtime control
     for partial SMT enablement on top

     The core support has also been provided to the PowerPC maintainers
     who added the PowerPC related changes on top

   - Minor cleanups and documentation updates"

* tag 'smp-core-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Documentation: core-api/cpuhotplug: Fix state names
  cpu/hotplug: Remove unused function declaration cpu_set_state_online()
  cpu/SMT: Fix cpu_smt_possible() comment
  cpu/SMT: Allow enabling partial SMT states via sysfs
  cpu/SMT: Create topology_smt_thread_allowed()
  cpu/SMT: Remove topology_smt_supported()
  cpu/SMT: Store the current/max number of threads
  cpu/SMT: Move smt/control simple exit cases earlier
  cpu/SMT: Move SMT prototypes into cpu_smt.h
  cpu/hotplug: Remove dependancy against cpu_primary_thread_mask
2023-08-28 15:04:43 -07:00

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/* SPDX-License-Identifier: GPL-2.0 */
/*
* include/linux/cpu.h - generic cpu definition
*
* This is mainly for topological representation. We define the
* basic 'struct cpu' here, which can be embedded in per-arch
* definitions of processors.
*
* Basic handling of the devices is done in drivers/base/cpu.c
*
* CPUs are exported via sysfs in the devices/system/cpu
* directory.
*/
#ifndef _LINUX_CPU_H_
#define _LINUX_CPU_H_
#include <linux/node.h>
#include <linux/compiler.h>
#include <linux/cpumask.h>
#include <linux/cpuhotplug.h>
#include <linux/cpu_smt.h>
struct device;
struct device_node;
struct attribute_group;
struct cpu {
int node_id; /* The node which contains the CPU */
int hotpluggable; /* creates sysfs control file if hotpluggable */
struct device dev;
};
extern void boot_cpu_init(void);
extern void boot_cpu_hotplug_init(void);
extern void cpu_init(void);
extern void trap_init(void);
extern int register_cpu(struct cpu *cpu, int num);
extern struct device *get_cpu_device(unsigned cpu);
extern bool cpu_is_hotpluggable(unsigned cpu);
extern bool arch_match_cpu_phys_id(int cpu, u64 phys_id);
extern bool arch_find_n_match_cpu_physical_id(struct device_node *cpun,
int cpu, unsigned int *thread);
extern int cpu_add_dev_attr(struct device_attribute *attr);
extern void cpu_remove_dev_attr(struct device_attribute *attr);
extern int cpu_add_dev_attr_group(struct attribute_group *attrs);
extern void cpu_remove_dev_attr_group(struct attribute_group *attrs);
extern ssize_t cpu_show_meltdown(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_spectre_v1(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_spectre_v2(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_spec_store_bypass(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_l1tf(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_mds(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_tsx_async_abort(struct device *dev,
struct device_attribute *attr,
char *buf);
extern ssize_t cpu_show_itlb_multihit(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_mmio_stale_data(struct device *dev,
struct device_attribute *attr,
char *buf);
extern ssize_t cpu_show_retbleed(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_spec_rstack_overflow(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_gds(struct device *dev,
struct device_attribute *attr, char *buf);
extern __printf(4, 5)
struct device *cpu_device_create(struct device *parent, void *drvdata,
const struct attribute_group **groups,
const char *fmt, ...);
#ifdef CONFIG_HOTPLUG_CPU
extern void unregister_cpu(struct cpu *cpu);
extern ssize_t arch_cpu_probe(const char *, size_t);
extern ssize_t arch_cpu_release(const char *, size_t);
#endif
/*
* These states are not related to the core CPU hotplug mechanism. They are
* used by various (sub)architectures to track internal state
*/
#define CPU_ONLINE 0x0002 /* CPU is up */
#define CPU_UP_PREPARE 0x0003 /* CPU coming up */
#define CPU_DEAD 0x0007 /* CPU dead */
#define CPU_DEAD_FROZEN 0x0008 /* CPU timed out on unplug */
#define CPU_POST_DEAD 0x0009 /* CPU successfully unplugged */
#define CPU_BROKEN 0x000B /* CPU did not die properly */
#ifdef CONFIG_SMP
extern bool cpuhp_tasks_frozen;
int add_cpu(unsigned int cpu);
int cpu_device_up(struct device *dev);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void);
int bringup_hibernate_cpu(unsigned int sleep_cpu);
void bringup_nonboot_cpus(unsigned int setup_max_cpus);
#else /* CONFIG_SMP */
#define cpuhp_tasks_frozen 0
static inline void cpu_maps_update_begin(void)
{
}
static inline void cpu_maps_update_done(void)
{
}
static inline int add_cpu(unsigned int cpu) { return 0;}
#endif /* CONFIG_SMP */
extern struct bus_type cpu_subsys;
extern int lockdep_is_cpus_held(void);
#ifdef CONFIG_HOTPLUG_CPU
extern void cpus_write_lock(void);
extern void cpus_write_unlock(void);
extern void cpus_read_lock(void);
extern void cpus_read_unlock(void);
extern int cpus_read_trylock(void);
extern void lockdep_assert_cpus_held(void);
extern void cpu_hotplug_disable(void);
extern void cpu_hotplug_enable(void);
void clear_tasks_mm_cpumask(int cpu);
int remove_cpu(unsigned int cpu);
int cpu_device_down(struct device *dev);
extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);
#else /* CONFIG_HOTPLUG_CPU */
static inline void cpus_write_lock(void) { }
static inline void cpus_write_unlock(void) { }
static inline void cpus_read_lock(void) { }
static inline void cpus_read_unlock(void) { }
static inline int cpus_read_trylock(void) { return true; }
static inline void lockdep_assert_cpus_held(void) { }
static inline void cpu_hotplug_disable(void) { }
static inline void cpu_hotplug_enable(void) { }
static inline int remove_cpu(unsigned int cpu) { return -EPERM; }
static inline void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) { }
#endif /* !CONFIG_HOTPLUG_CPU */
#ifdef CONFIG_PM_SLEEP_SMP
extern int freeze_secondary_cpus(int primary);
extern void thaw_secondary_cpus(void);
static inline int suspend_disable_secondary_cpus(void)
{
int cpu = 0;
if (IS_ENABLED(CONFIG_PM_SLEEP_SMP_NONZERO_CPU))
cpu = -1;
return freeze_secondary_cpus(cpu);
}
static inline void suspend_enable_secondary_cpus(void)
{
return thaw_secondary_cpus();
}
#else /* !CONFIG_PM_SLEEP_SMP */
static inline void thaw_secondary_cpus(void) {}
static inline int suspend_disable_secondary_cpus(void) { return 0; }
static inline void suspend_enable_secondary_cpus(void) { }
#endif /* !CONFIG_PM_SLEEP_SMP */
void __noreturn cpu_startup_entry(enum cpuhp_state state);
void cpu_idle_poll_ctrl(bool enable);
bool cpu_in_idle(unsigned long pc);
void arch_cpu_idle(void);
void arch_cpu_idle_prepare(void);
void arch_cpu_idle_enter(void);
void arch_cpu_idle_exit(void);
void __noreturn arch_cpu_idle_dead(void);
#ifdef CONFIG_ARCH_HAS_CPU_FINALIZE_INIT
void arch_cpu_finalize_init(void);
#else
static inline void arch_cpu_finalize_init(void) { }
#endif
void play_idle_precise(u64 duration_ns, u64 latency_ns);
static inline void play_idle(unsigned long duration_us)
{
play_idle_precise(duration_us * NSEC_PER_USEC, U64_MAX);
}
#ifdef CONFIG_HOTPLUG_CPU
void cpuhp_report_idle_dead(void);
#else
static inline void cpuhp_report_idle_dead(void) { }
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
extern bool cpu_mitigations_off(void);
extern bool cpu_mitigations_auto_nosmt(void);
#endif /* _LINUX_CPU_H_ */
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