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Merge branch 'topic/cpu-smt' into next

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Merge SMT changes we are sharing with the tip tree.
This commit is contained in:
Michael Ellerman 2023-08-14 21:46:03 +10:00
commit 15f63e306d
15 changed files with 196 additions and 85 deletions
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1
Documentation/ABI/testing/sysfs-devices-system-cpu
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@ -555,6 +555,7 @@ Description: Control Symmetric Multi Threading (SMT)
================ =========================================
"on" SMT is enabled
"off" SMT is disabled
"<N>" SMT is enabled with N threads per core.
"forceoff" SMT is force disabled. Cannot be changed.
"notsupported" SMT is not supported by the CPU
"notimplemented" SMT runtime toggling is not

4
Documentation/admin-guide/kernel-parameters.txt
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@ -3853,10 +3853,10 @@
nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
and disable the IO APIC. legacy for "maxcpus=0".
nosmt [KNL,MIPS,S390] Disable symmetric multithreading (SMT).
nosmt [KNL,MIPS,PPC,S390] Disable symmetric multithreading (SMT).
Equivalent to smt=1.
[KNL,X86] Disable symmetric multithreading (SMT).
[KNL,X86,PPC] Disable symmetric multithreading (SMT).
nosmt=force: Force disable SMT, cannot be undone
via the sysfs control file.

3
arch/Kconfig
View File

@ -34,6 +34,9 @@ config ARCH_HAS_SUBPAGE_FAULTS
config HOTPLUG_SMT
bool
config SMT_NUM_THREADS_DYNAMIC
bool
# Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL
config HOTPLUG_CORE_SYNC
bool

2
arch/powerpc/Kconfig
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@ -272,6 +272,8 @@ config PPC
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_VIRT_CPU_ACCOUNTING
select HAVE_VIRT_CPU_ACCOUNTING_GEN
select HOTPLUG_SMT if HOTPLUG_CPU
select SMT_NUM_THREADS_DYNAMIC
select HUGETLB_PAGE_SIZE_VARIABLE if PPC_BOOK3S_64 && HUGETLB_PAGE
select IOMMU_HELPER if PPC64
select IRQ_DOMAIN

15
arch/powerpc/include/asm/topology.h
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@ -143,5 +143,20 @@ static inline int cpu_to_coregroup_id(int cpu)
#endif
#endif
#ifdef CONFIG_HOTPLUG_SMT
#include <linux/cpu_smt.h>
#include <asm/cputhreads.h>
static inline bool topology_is_primary_thread(unsigned int cpu)
{
return cpu == cpu_first_thread_sibling(cpu);
}
static inline bool topology_smt_thread_allowed(unsigned int cpu)
{
return cpu_thread_in_core(cpu) < cpu_smt_num_threads;
}
#endif
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_TOPOLOGY_H */

8
arch/powerpc/kernel/smp.c
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@ -1088,7 +1088,7 @@ static int __init init_big_cores(void)
void __init smp_prepare_cpus(unsigned int max_cpus)
{
unsigned int cpu;
unsigned int cpu, num_threads;
DBG("smp_prepare_cpus\n");
@ -1155,6 +1155,12 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
if (smp_ops && smp_ops->probe)
smp_ops->probe();
// Initalise the generic SMT topology support
num_threads = 1;
if (smt_enabled_at_boot)
num_threads = smt_enabled_at_boot;
cpu_smt_set_num_threads(num_threads, threads_per_core);
}
void smp_prepare_boot_cpu(void)

30
arch/powerpc/platforms/pseries/hotplug-cpu.c
View File

@ -398,6 +398,14 @@ static int dlpar_online_cpu(struct device_node *dn)
for_each_present_cpu(cpu) {
if (get_hard_smp_processor_id(cpu) != thread)
continue;
if (!topology_is_primary_thread(cpu)) {
if (cpu_smt_control != CPU_SMT_ENABLED)
break;
if (!topology_smt_thread_allowed(cpu))
break;
}
cpu_maps_update_done();
find_and_update_cpu_nid(cpu);
rc = device_online(get_cpu_device(cpu));
@ -845,15 +853,9 @@ static struct notifier_block pseries_smp_nb = {
.notifier_call = pseries_smp_notifier,
};
static int __init pseries_cpu_hotplug_init(void)
void __init pseries_cpu_hotplug_init(void)
{
int qcss_tok;
unsigned int node;
#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
ppc_md.cpu_probe = dlpar_cpu_probe;
ppc_md.cpu_release = dlpar_cpu_release;
#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
rtas_stop_self_token = rtas_function_token(RTAS_FN_STOP_SELF);
qcss_tok = rtas_function_token(RTAS_FN_QUERY_CPU_STOPPED_STATE);
@ -862,12 +864,22 @@ static int __init pseries_cpu_hotplug_init(void)
qcss_tok == RTAS_UNKNOWN_SERVICE) {
printk(KERN_INFO "CPU Hotplug not supported by firmware "
"- disabling.\n");
return 0;
return;
}
smp_ops->cpu_offline_self = pseries_cpu_offline_self;
smp_ops->cpu_disable = pseries_cpu_disable;
smp_ops->cpu_die = pseries_cpu_die;
}
static int __init pseries_dlpar_init(void)
{
unsigned int node;
#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
ppc_md.cpu_probe = dlpar_cpu_probe;
ppc_md.cpu_release = dlpar_cpu_release;
#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
/* Processors can be added/removed only on LPAR */
if (firmware_has_feature(FW_FEATURE_LPAR)) {
@ -886,4 +898,4 @@ static int __init pseries_cpu_hotplug_init(void)
return 0;
}
machine_arch_initcall(pseries, pseries_cpu_hotplug_init);
machine_arch_initcall(pseries, pseries_dlpar_init);

2
arch/powerpc/platforms/pseries/pseries.h
View File

@ -75,11 +75,13 @@ static inline int dlpar_hp_pmem(struct pseries_hp_errorlog *hp_elog)
#ifdef CONFIG_HOTPLUG_CPU
int dlpar_cpu(struct pseries_hp_errorlog *hp_elog);
void pseries_cpu_hotplug_init(void);
#else
static inline int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
{
return -EOPNOTSUPP;
}
static inline void pseries_cpu_hotplug_init(void) { }
#endif
/* PCI root bridge prepare function override for pseries */

2
arch/powerpc/platforms/pseries/setup.c
View File

@ -816,6 +816,8 @@ static void __init pSeries_setup_arch(void)
/* Discover PIC type and setup ppc_md accordingly */
smp_init_pseries();
// Setup CPU hotplug callbacks
pseries_cpu_hotplug_init();
if (radix_enabled() && !mmu_has_feature(MMU_FTR_GTSE))
if (!firmware_has_feature(FW_FEATURE_RPT_INVALIDATE))

4
arch/x86/include/asm/topology.h
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@ -136,10 +136,11 @@ static inline int topology_max_smt_threads(void)
return __max_smt_threads;
}
#include <linux/cpu_smt.h>
int topology_update_package_map(unsigned int apicid, unsigned int cpu);
int topology_update_die_map(unsigned int dieid, unsigned int cpu);
int topology_phys_to_logical_pkg(unsigned int pkg);
bool topology_smt_supported(void);
extern struct cpumask __cpu_primary_thread_mask;
#define cpu_primary_thread_mask ((const struct cpumask *)&__cpu_primary_thread_mask)
@ -162,7 +163,6 @@ static inline int topology_phys_to_logical_pkg(unsigned int pkg) { return 0; }
static inline int topology_max_die_per_package(void) { return 1; }
static inline int topology_max_smt_threads(void) { return 1; }
static inline bool topology_is_primary_thread(unsigned int cpu) { return true; }
static inline bool topology_smt_supported(void) { return false; }
#endif /* !CONFIG_SMP */
static inline void arch_fix_phys_package_id(int num, u32 slot)

2
arch/x86/kernel/cpu/common.c
View File

@ -2317,7 +2317,7 @@ void __init arch_cpu_finalize_init(void)
* identify_boot_cpu() initialized SMT support information, let the
* core code know.
*/
cpu_smt_check_topology();
cpu_smt_set_num_threads(smp_num_siblings, smp_num_siblings);
if (!IS_ENABLED(CONFIG_SMP)) {
pr_info("CPU: ");

8
arch/x86/kernel/smpboot.c
View File

@ -326,14 +326,6 @@ static void notrace start_secondary(void *unused)
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}
/**
* topology_smt_supported - Check whether SMT is supported by the CPUs
*/
bool topology_smt_supported(void)
{
return smp_num_siblings > 1;
}
/**
* topology_phys_to_logical_pkg - Map a physical package id to a logical
* @phys_pkg: The physical package id to map

25
include/linux/cpu.h
View File

@ -18,6 +18,7 @@
#include <linux/compiler.h>
#include <linux/cpumask.h>
#include <linux/cpuhotplug.h>
#include <linux/cpu_smt.h>
struct device;
struct device_node;
@ -204,30 +205,6 @@ void cpuhp_report_idle_dead(void);
static inline void cpuhp_report_idle_dead(void) { }
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
enum cpuhp_smt_control {
CPU_SMT_ENABLED,
CPU_SMT_DISABLED,
CPU_SMT_FORCE_DISABLED,
CPU_SMT_NOT_SUPPORTED,
CPU_SMT_NOT_IMPLEMENTED,
};
#if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT)
extern enum cpuhp_smt_control cpu_smt_control;
extern void cpu_smt_disable(bool force);
extern void cpu_smt_check_topology(void);
extern bool cpu_smt_possible(void);
extern int cpuhp_smt_enable(void);
extern int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval);
#else
# define cpu_smt_control (CPU_SMT_NOT_IMPLEMENTED)
static inline void cpu_smt_disable(bool force) { }
static inline void cpu_smt_check_topology(void) { }
static inline bool cpu_smt_possible(void) { return false; }
static inline int cpuhp_smt_enable(void) { return 0; }
static inline int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) { return 0; }
#endif
extern bool cpu_mitigations_off(void);
extern bool cpu_mitigations_auto_nosmt(void);

33
include/linux/cpu_smt.h Normal file
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@ -0,0 +1,33 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_CPU_SMT_H_
#define _LINUX_CPU_SMT_H_
enum cpuhp_smt_control {
CPU_SMT_ENABLED,
CPU_SMT_DISABLED,
CPU_SMT_FORCE_DISABLED,
CPU_SMT_NOT_SUPPORTED,
CPU_SMT_NOT_IMPLEMENTED,
};
#if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT)
extern enum cpuhp_smt_control cpu_smt_control;
extern unsigned int cpu_smt_num_threads;
extern void cpu_smt_disable(bool force);
extern void cpu_smt_set_num_threads(unsigned int num_threads,
unsigned int max_threads);
extern bool cpu_smt_possible(void);
extern int cpuhp_smt_enable(void);
extern int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval);
#else
# define cpu_smt_control (CPU_SMT_NOT_IMPLEMENTED)
# define cpu_smt_num_threads 1
static inline void cpu_smt_disable(bool force) { }
static inline void cpu_smt_set_num_threads(unsigned int num_threads,
unsigned int max_threads) { }
static inline bool cpu_smt_possible(void) { return false; }
static inline int cpuhp_smt_enable(void) { return 0; }
static inline int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) { return 0; }
#endif
#endif /* _LINUX_CPU_SMT_H_ */

142
kernel/cpu.c
View File

@ -592,7 +592,10 @@ static void lockdep_release_cpus_lock(void)
void __weak arch_smt_update(void) { }
#ifdef CONFIG_HOTPLUG_SMT
enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED;
static unsigned int cpu_smt_max_threads __ro_after_init;
unsigned int cpu_smt_num_threads __read_mostly = UINT_MAX;
void __init cpu_smt_disable(bool force)
{
@ -606,16 +609,33 @@ void __init cpu_smt_disable(bool force)
pr_info("SMT: disabled\n");
cpu_smt_control = CPU_SMT_DISABLED;
}
cpu_smt_num_threads = 1;
}
/*
* The decision whether SMT is supported can only be done after the full
* CPU identification. Called from architecture code.
*/
void __init cpu_smt_check_topology(void)
void __init cpu_smt_set_num_threads(unsigned int num_threads,
unsigned int max_threads)
{
if (!topology_smt_supported())
WARN_ON(!num_threads || (num_threads > max_threads));
if (max_threads == 1)
cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
cpu_smt_max_threads = max_threads;
/*
* If SMT has been disabled via the kernel command line or SMT is
* not supported, set cpu_smt_num_threads to 1 for consistency.
* If enabled, take the architecture requested number of threads
* to bring up into account.
*/
if (cpu_smt_control != CPU_SMT_ENABLED)
cpu_smt_num_threads = 1;
else if (num_threads < cpu_smt_num_threads)
cpu_smt_num_threads = num_threads;
}
static int __init smt_cmdline_disable(char *str)
@ -625,9 +645,23 @@ static int __init smt_cmdline_disable(char *str)
}
early_param("nosmt", smt_cmdline_disable);
/*
* For Archicture supporting partial SMT states check if the thread is allowed.
* Otherwise this has already been checked through cpu_smt_max_threads when
* setting the SMT level.
*/
static inline bool cpu_smt_thread_allowed(unsigned int cpu)
{
#ifdef CONFIG_SMT_NUM_THREADS_DYNAMIC
return topology_smt_thread_allowed(cpu);
#else
return true;
#endif
}
static inline bool cpu_smt_allowed(unsigned int cpu)
{
if (cpu_smt_control == CPU_SMT_ENABLED)
if (cpu_smt_control == CPU_SMT_ENABLED && cpu_smt_thread_allowed(cpu))
return true;
if (topology_is_primary_thread(cpu))
@ -650,22 +684,8 @@ bool cpu_smt_possible(void)
}
EXPORT_SYMBOL_GPL(cpu_smt_possible);
static inline bool cpuhp_smt_aware(void)
{
return topology_smt_supported();
}
static inline const struct cpumask *cpuhp_get_primary_thread_mask(void)
{
return cpu_primary_thread_mask;
}
#else
static inline bool cpu_smt_allowed(unsigned int cpu) { return true; }
static inline bool cpuhp_smt_aware(void) { return false; }
static inline const struct cpumask *cpuhp_get_primary_thread_mask(void)
{
return cpu_present_mask;
}
#endif
static inline enum cpuhp_state
@ -1793,6 +1813,16 @@ static int __init parallel_bringup_parse_param(char *arg)
}
early_param("cpuhp.parallel", parallel_bringup_parse_param);
static inline bool cpuhp_smt_aware(void)
{
return cpu_smt_max_threads > 1;
}
static inline const struct cpumask *cpuhp_get_primary_thread_mask(void)
{
return cpu_primary_thread_mask;
}
/*
* On architectures which have enabled parallel bringup this invokes all BP
* prepare states for each of the to be onlined APs first. The last state
@ -2626,6 +2656,12 @@ int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
for_each_online_cpu(cpu) {
if (topology_is_primary_thread(cpu))
continue;
/*
* Disable can be called with CPU_SMT_ENABLED when changing
* from a higher to lower number of SMT threads per core.
*/
if (ctrlval == CPU_SMT_ENABLED && cpu_smt_thread_allowed(cpu))
continue;
ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
if (ret)
break;
@ -2660,6 +2696,8 @@ int cpuhp_smt_enable(void)
/* Skip online CPUs and CPUs on offline nodes */
if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
continue;
if (!cpu_smt_thread_allowed(cpu))
continue;
ret = _cpu_up(cpu, 0, CPUHP_ONLINE);
if (ret)
break;
@ -2838,20 +2876,19 @@ static const struct attribute_group cpuhp_cpu_root_attr_group = {
#ifdef CONFIG_HOTPLUG_SMT
static bool cpu_smt_num_threads_valid(unsigned int threads)
{
if (IS_ENABLED(CONFIG_SMT_NUM_THREADS_DYNAMIC))
return threads >= 1 && threads <= cpu_smt_max_threads;
return threads == 1 || threads == cpu_smt_max_threads;
}
static ssize_t
__store_smt_control(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
int ctrlval, ret;
if (sysfs_streq(buf, "on"))
ctrlval = CPU_SMT_ENABLED;
else if (sysfs_streq(buf, "off"))
ctrlval = CPU_SMT_DISABLED;
else if (sysfs_streq(buf, "forceoff"))
ctrlval = CPU_SMT_FORCE_DISABLED;
else
return -EINVAL;
int ctrlval, ret, num_threads, orig_threads;
bool force_off;
if (cpu_smt_control == CPU_SMT_FORCE_DISABLED)
return -EPERM;
@ -2859,21 +2896,39 @@ __store_smt_control(struct device *dev, struct device_attribute *attr,
if (cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
return -ENODEV;
if (sysfs_streq(buf, "on")) {
ctrlval = CPU_SMT_ENABLED;
num_threads = cpu_smt_max_threads;
} else if (sysfs_streq(buf, "off")) {
ctrlval = CPU_SMT_DISABLED;
num_threads = 1;
} else if (sysfs_streq(buf, "forceoff")) {
ctrlval = CPU_SMT_FORCE_DISABLED;
num_threads = 1;
} else if (kstrtoint(buf, 10, &num_threads) == 0) {
if (num_threads == 1)
ctrlval = CPU_SMT_DISABLED;
else if (cpu_smt_num_threads_valid(num_threads))
ctrlval = CPU_SMT_ENABLED;
else
return -EINVAL;
} else {
return -EINVAL;
}
ret = lock_device_hotplug_sysfs();
if (ret)
return ret;
if (ctrlval != cpu_smt_control) {
switch (ctrlval) {
case CPU_SMT_ENABLED:
ret = cpuhp_smt_enable();
break;
case CPU_SMT_DISABLED:
case CPU_SMT_FORCE_DISABLED:
ret = cpuhp_smt_disable(ctrlval);
break;
}
}
orig_threads = cpu_smt_num_threads;
cpu_smt_num_threads = num_threads;
force_off = ctrlval != cpu_smt_control && ctrlval == CPU_SMT_FORCE_DISABLED;
if (num_threads > orig_threads)
ret = cpuhp_smt_enable();
else if (num_threads < orig_threads || force_off)
ret = cpuhp_smt_disable(ctrlval);
unlock_device_hotplug();
return ret ? ret : count;
@ -2901,6 +2956,17 @@ static ssize_t control_show(struct device *dev,
{
const char *state = smt_states[cpu_smt_control];
#ifdef CONFIG_HOTPLUG_SMT
/*
* If SMT is enabled but not all threads are enabled then show the
* number of threads. If all threads are enabled show "on". Otherwise
* show the state name.
*/
if (cpu_smt_control == CPU_SMT_ENABLED &&
cpu_smt_num_threads != cpu_smt_max_threads)
return sysfs_emit(buf, "%d\n", cpu_smt_num_threads);
#endif
return snprintf(buf, PAGE_SIZE - 2, "%s\n", state);
}