Commit 76e4f660 authored by Ashok Raj's avatar Ashok Raj Committed by Linus Torvalds
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[PATCH] x86_64: CPU hotplug support



  Experimental CPU hotplug patch for x86_64
  -----------------------------------------
This supports logical CPU online and offline.
- Test with maxcpus=1, and then kick other cpu's off to test if init code
  is all cleaned up. CONFIG_SCHED_SMT works as well.
- idle threads are forked on demand from keventd threads for clean startup

TBD:
1. Not tested on a real NUMA machine (tested with numa=fake=2)
2. Handle ACPI pieces for physical hotplug support.
Signed-off-by: default avatarAshok Raj <ashok.raj@intel.com>
Acked-by: default avatarAndi Kleen <ak@muc.de>
Acked-by: default avatarZwane Mwaikambo <zwane@arm.linux.org.uk>
Signed-off-by: Shaohua.li<shaohua.li@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent e6982c67
......@@ -73,12 +73,11 @@ static int __init topology_init(void)
{
int i;
for (i = 0; i < MAX_NUMNODES; i++) {
if (node_online(i))
arch_register_node(i);
}
for (i = 0; i < NR_CPUS; i++)
if (cpu_possible(i)) arch_register_cpu(i);
for_each_online_node(i)
arch_register_node(i);
for_each_cpu(i)
arch_register_cpu(i);
return 0;
}
......@@ -88,8 +87,8 @@ static int __init topology_init(void)
{
int i;
for (i = 0; i < NR_CPUS; i++)
if (cpu_possible(i)) arch_register_cpu(i);
for_each_cpu(i)
arch_register_cpu(i);
return 0;
}
......
......@@ -313,6 +313,15 @@ config NR_CPUS
This is purely to save memory - each supported CPU requires
memory in the static kernel configuration.
config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
depends on SMP && HOTPLUG && EXPERIMENTAL
help
Say Y here to experiment with turning CPUs off and on. CPUs
can be controlled through /sys/devices/system/cpu/cpu#.
Say N if you want to disable CPU hotplug.
config HPET_TIMER
bool
default y
......
......@@ -14,6 +14,7 @@
#include <linux/interrupt.h>
#include <linux/seq_file.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/io_apic.h>
......@@ -106,3 +107,31 @@ asmlinkage unsigned int do_IRQ(struct pt_regs *regs)
return 1;
}
#ifdef CONFIG_HOTPLUG_CPU
void fixup_irqs(cpumask_t map)
{
unsigned int irq;
static int warned;
for (irq = 0; irq < NR_IRQS; irq++) {
cpumask_t mask;
if (irq == 2)
continue;
cpus_and(mask, irq_affinity[irq], map);
if (any_online_cpu(mask) == NR_CPUS) {
printk("Breaking affinity for irq %i\n", irq);
mask = map;
}
if (irq_desc[irq].handler->set_affinity)
irq_desc[irq].handler->set_affinity(irq, mask);
else if (irq_desc[irq].action && !(warned++))
printk("Cannot set affinity for irq %i\n", irq);
}
/* That doesn't seem sufficient. Give it 1ms. */
local_irq_enable();
mdelay(1);
local_irq_disable();
}
#endif
......@@ -8,7 +8,8 @@
*
* X86-64 port
* Andi Kleen.
*
*
* CPU hotplug support - ashok.raj@intel.com
* $Id: process.c,v 1.38 2002/01/15 10:08:03 ak Exp $
*/
......@@ -18,6 +19,7 @@
#include <stdarg.h>
#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
......@@ -154,6 +156,29 @@ void cpu_idle_wait(void)
}
EXPORT_SYMBOL_GPL(cpu_idle_wait);
#ifdef CONFIG_HOTPLUG_CPU
DECLARE_PER_CPU(int, cpu_state);
#include <asm/nmi.h>
/* We don't actually take CPU down, just spin without interrupts. */
static inline void play_dead(void)
{
idle_task_exit();
wbinvd();
mb();
/* Ack it */
__get_cpu_var(cpu_state) = CPU_DEAD;
while (1)
safe_halt();
}
#else
static inline void play_dead(void)
{
BUG();
}
#endif /* CONFIG_HOTPLUG_CPU */
/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
......@@ -174,6 +199,8 @@ void cpu_idle (void)
idle = pm_idle;
if (!idle)
idle = default_idle;
if (cpu_is_offline(smp_processor_id()))
play_dead();
idle();
}
......
......@@ -34,6 +34,7 @@
* Andi Kleen : Converted to new state machine.
* Various cleanups.
* Probably mostly hotplug CPU ready now.
* Ashok Raj : CPU hotplug support
*/
......@@ -98,6 +99,37 @@ EXPORT_SYMBOL(cpu_core_map);
extern unsigned char trampoline_data[];
extern unsigned char trampoline_end[];
/* State of each CPU */
DEFINE_PER_CPU(int, cpu_state) = { 0 };
/*
* Store all idle threads, this can be reused instead of creating
* a new thread. Also avoids complicated thread destroy functionality
* for idle threads.
*/
struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
#define get_idle_for_cpu(x) (idle_thread_array[(x)])
#define set_idle_for_cpu(x,p) (idle_thread_array[(x)] = (p))
/*
* cpu_possible_map should be static, it cannot change as cpu's
* are onlined, or offlined. The reason is per-cpu data-structures
* are allocated by some modules at init time, and dont expect to
* do this dynamically on cpu arrival/departure.
* cpu_present_map on the other hand can change dynamically.
* In case when cpu_hotplug is not compiled, then we resort to current
* behaviour, which is cpu_possible == cpu_present.
* If cpu-hotplug is supported, then we need to preallocate for all
* those NR_CPUS, hence cpu_possible_map represents entire NR_CPUS range.
* - Ashok Raj
*/
#ifdef CONFIG_HOTPLUG_CPU
#define fixup_cpu_possible_map(x) cpu_set((x), cpu_possible_map)
#else
#define fixup_cpu_possible_map(x)
#endif
/*
* Currently trivial. Write the real->protected mode
* bootstrap into the page concerned. The caller
......@@ -623,33 +655,77 @@ static int __cpuinit wakeup_secondary_via_INIT(int phys_apicid, unsigned int sta
return (send_status | accept_status);
}
struct create_idle {
struct task_struct *idle;
struct completion done;
int cpu;
};
void do_fork_idle(void *_c_idle)
{
struct create_idle *c_idle = _c_idle;
c_idle->idle = fork_idle(c_idle->cpu);
complete(&c_idle->done);
}
/*
* Boot one CPU.
*/
static int __cpuinit do_boot_cpu(int cpu, int apicid)
{
struct task_struct *idle;
unsigned long boot_error;
int timeout;
unsigned long start_rip;
struct create_idle c_idle = {
.cpu = cpu,
.done = COMPLETION_INITIALIZER(c_idle.done),
};
DECLARE_WORK(work, do_fork_idle, &c_idle);
c_idle.idle = get_idle_for_cpu(cpu);
if (c_idle.idle) {
c_idle.idle->thread.rsp = (unsigned long) (((struct pt_regs *)
(THREAD_SIZE + (unsigned long) c_idle.idle->thread_info)) - 1);
init_idle(c_idle.idle, cpu);
goto do_rest;
}
/*
* We can't use kernel_thread since we must avoid to
* reschedule the child.
* During cold boot process, keventd thread is not spun up yet.
* When we do cpu hot-add, we create idle threads on the fly, we should
* not acquire any attributes from the calling context. Hence the clean
* way to create kernel_threads() is to do that from keventd().
* We do the current_is_keventd() due to the fact that ACPI notifier
* was also queuing to keventd() and when the caller is already running
* in context of keventd(), we would end up with locking up the keventd
* thread.
*/
idle = fork_idle(cpu);
if (IS_ERR(idle)) {
if (!keventd_up() || current_is_keventd())
work.func(work.data);
else {
schedule_work(&work);
wait_for_completion(&c_idle.done);
}
if (IS_ERR(c_idle.idle)) {
printk("failed fork for CPU %d\n", cpu);
return PTR_ERR(idle);
return PTR_ERR(c_idle.idle);
}
cpu_pda[cpu].pcurrent = idle;
set_idle_for_cpu(cpu, c_idle.idle);
do_rest:
cpu_pda[cpu].pcurrent = c_idle.idle;
start_rip = setup_trampoline();
init_rsp = idle->thread.rsp;
init_rsp = c_idle.idle->thread.rsp;
per_cpu(init_tss,cpu).rsp0 = init_rsp;
initial_code = start_secondary;
clear_ti_thread_flag(idle->thread_info, TIF_FORK);
clear_ti_thread_flag(c_idle.idle->thread_info, TIF_FORK);
printk(KERN_INFO "Booting processor %d/%d rip %lx rsp %lx\n", cpu, apicid,
start_rip, init_rsp);
......@@ -925,10 +1001,9 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
int apicid = cpu_present_to_apicid(i);
if (physid_isset(apicid, phys_cpu_present_map)) {
cpu_set(i, cpu_present_map);
/* possible map would be different if we supported real
CPU hotplug. */
cpu_set(i, cpu_possible_map);
}
fixup_cpu_possible_map(i);
}
if (smp_sanity_check(max_cpus) < 0) {
......@@ -977,9 +1052,6 @@ void __init smp_prepare_boot_cpu(void)
/*
* Entry point to boot a CPU.
*
* This is all __cpuinit, not __devinit for now because we don't support
* CPU hotplug (yet).
*/
int __cpuinit __cpu_up(unsigned int cpu)
{
......@@ -996,6 +1068,14 @@ int __cpuinit __cpu_up(unsigned int cpu)
return -EINVAL;
}
/*
* Already booted CPU?
*/
if (cpu_isset(cpu, cpu_callin_map)) {
Dprintk("do_boot_cpu %d Already started\n", cpu);
return -ENOSYS;
}
/* Boot it! */
err = do_boot_cpu(cpu, apicid);
if (err < 0) {
......@@ -1008,7 +1088,9 @@ int __cpuinit __cpu_up(unsigned int cpu)
while (!cpu_isset(cpu, cpu_online_map))
cpu_relax();
return 0;
err = 0;
return err;
}
/*
......@@ -1016,7 +1098,9 @@ int __cpuinit __cpu_up(unsigned int cpu)
*/
void __init smp_cpus_done(unsigned int max_cpus)
{
#ifndef CONFIG_HOTPLUG_CPU
zap_low_mappings();
#endif
smp_cleanup_boot();
#ifdef CONFIG_X86_IO_APIC
......@@ -1028,3 +1112,94 @@ void __init smp_cpus_done(unsigned int max_cpus)
check_nmi_watchdog();
}
#ifdef CONFIG_HOTPLUG_CPU
static void
remove_siblinginfo(int cpu)
{
int sibling;
for_each_cpu_mask(sibling, cpu_sibling_map[cpu])
cpu_clear(cpu, cpu_sibling_map[sibling]);
for_each_cpu_mask(sibling, cpu_core_map[cpu])
cpu_clear(cpu, cpu_core_map[sibling]);
cpus_clear(cpu_sibling_map[cpu]);
cpus_clear(cpu_core_map[cpu]);
phys_proc_id[cpu] = BAD_APICID;
cpu_core_id[cpu] = BAD_APICID;
}
void remove_cpu_from_maps(void)
{
int cpu = smp_processor_id();
cpu_clear(cpu, cpu_callout_map);
cpu_clear(cpu, cpu_callin_map);
clear_bit(cpu, &cpu_initialized); /* was set by cpu_init() */
}
int __cpu_disable(void)
{
int cpu = smp_processor_id();
/*
* Perhaps use cpufreq to drop frequency, but that could go
* into generic code.
*
* We won't take down the boot processor on i386 due to some
* interrupts only being able to be serviced by the BSP.
* Especially so if we're not using an IOAPIC -zwane
*/
if (cpu == 0)
return -EBUSY;
disable_APIC_timer();
/*
* HACK:
* Allow any queued timer interrupts to get serviced
* This is only a temporary solution until we cleanup
* fixup_irqs as we do for IA64.
*/
local_irq_enable();
mdelay(1);
local_irq_disable();
remove_siblinginfo(cpu);
/* It's now safe to remove this processor from the online map */
cpu_clear(cpu, cpu_online_map);
remove_cpu_from_maps();
fixup_irqs(cpu_online_map);
return 0;
}
void __cpu_die(unsigned int cpu)
{
/* We don't do anything here: idle task is faking death itself. */
unsigned int i;
for (i = 0; i < 10; i++) {
/* They ack this in play_dead by setting CPU_DEAD */
if (per_cpu(cpu_state, cpu) == CPU_DEAD)
return;
current->state = TASK_UNINTERRUPTIBLE;
schedule_timeout(HZ/10);
}
printk(KERN_ERR "CPU %u didn't die...\n", cpu);
}
#else /* ... !CONFIG_HOTPLUG_CPU */
int __cpu_disable(void)
{
return -ENOSYS;
}
void __cpu_die(unsigned int cpu)
{
/* We said "no" in __cpu_disable */
BUG();
}
#endif /* CONFIG_HOTPLUG_CPU */
......@@ -586,11 +586,17 @@ static void unknown_nmi_error(unsigned char reason, struct pt_regs * regs)
asmlinkage void default_do_nmi(struct pt_regs *regs)
{
unsigned char reason = 0;
int cpu;
cpu = smp_processor_id();
/* Only the BSP gets external NMIs from the system. */
if (!smp_processor_id())
if (!cpu)
reason = get_nmi_reason();
if (!cpu_online(cpu))
return;
if (!(reason & 0xc0)) {
if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 0, SIGINT)
== NOTIFY_STOP)
......
......@@ -52,4 +52,9 @@ struct irqaction;
struct pt_regs;
int handle_IRQ_event(unsigned int, struct pt_regs *, struct irqaction *);
#ifdef CONFIG_HOTPLUG_CPU
#include <linux/cpumask.h>
extern void fixup_irqs(cpumask_t map);
#endif
#endif /* _ASM_IRQ_H */
......@@ -77,6 +77,8 @@ extern __inline int hard_smp_processor_id(void)
}
extern int safe_smp_processor_id(void);
extern int __cpu_disable(void);
extern void __cpu_die(unsigned int cpu);
#endif /* !ASSEMBLY */
......
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