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powerpc/powernv: Add CPU hotplug support

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Unplugged CPU go into NAP mode in a loop until woken up

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Benjamin Herrenschmidt 2011-09-19 17:44:54 +00:00
parent 78b782cb78
commit 344eb010b2
2 changed files with 78 additions and 2 deletions
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2
arch/powerpc/Kconfig
View File

@ -323,7 +323,7 @@ config SWIOTLB
config HOTPLUG_CPU
bool "Support for enabling/disabling CPUs"
depends on SMP && HOTPLUG && EXPERIMENTAL && (PPC_PSERIES || PPC_PMAC)
depends on SMP && HOTPLUG && EXPERIMENTAL && (PPC_PSERIES || PPC_PMAC || PPC_POWERNV)
---help---
Say Y here to be able to disable and re-enable individual
CPUs at runtime on SMP machines.

78
arch/powerpc/platforms/powernv/smp.c
View File

@ -33,7 +33,14 @@
#include "powernv.h"
static void __devinit pnv_smp_setup_cpu(int cpu)
#ifdef DEBUG
#include <asm/udbg.h>
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif
static void __cpuinit pnv_smp_setup_cpu(int cpu)
{
if (cpu != boot_cpuid)
xics_setup_cpu();
@ -55,6 +62,67 @@ static int pnv_smp_cpu_bootable(unsigned int nr)
return 1;
}
#ifdef CONFIG_HOTPLUG_CPU
static int pnv_smp_cpu_disable(void)
{
int cpu = smp_processor_id();
/* This is identical to pSeries... might consolidate by
* moving migrate_irqs_away to a ppc_md with default to
* the generic fixup_irqs. --BenH.
*/
set_cpu_online(cpu, false);
vdso_data->processorCount--;
if (cpu == boot_cpuid)
boot_cpuid = cpumask_any(cpu_online_mask);
xics_migrate_irqs_away();
return 0;
}
static void pnv_smp_cpu_kill_self(void)
{
unsigned int cpu;
/* If powersave_nap is enabled, use NAP mode, else just
* spin aimlessly
*/
if (!powersave_nap) {
generic_mach_cpu_die();
return;
}
/* Standard hot unplug procedure */
local_irq_disable();
idle_task_exit();
current->active_mm = NULL; /* for sanity */
cpu = smp_processor_id();
DBG("CPU%d offline\n", cpu);
generic_set_cpu_dead(cpu);
smp_wmb();
/* We don't want to take decrementer interrupts while we are offline,
* so clear LPCR:PECE1. We keep PECE2 enabled.
*/
mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
while (!generic_check_cpu_restart(cpu)) {
power7_idle();
if (!generic_check_cpu_restart(cpu)) {
DBG("CPU%d Unexpected exit while offline !\n", cpu);
/* We may be getting an IPI, so we re-enable
* interrupts to process it, it will be ignored
* since we aren't online (hopefully)
*/
local_irq_enable();
local_irq_disable();
}
}
mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
DBG("CPU%d coming online...\n", cpu);
}
#endif /* CONFIG_HOTPLUG_CPU */
static struct smp_ops_t pnv_smp_ops = {
.message_pass = smp_muxed_ipi_message_pass,
.cause_ipi = NULL, /* Filled at runtime by xics_smp_probe() */
@ -62,6 +130,10 @@ static struct smp_ops_t pnv_smp_ops = {
.kick_cpu = smp_generic_kick_cpu,
.setup_cpu = pnv_smp_setup_cpu,
.cpu_bootable = pnv_smp_cpu_bootable,
#ifdef CONFIG_HOTPLUG_CPU
.cpu_disable = pnv_smp_cpu_disable,
.cpu_die = generic_cpu_die,
#endif /* CONFIG_HOTPLUG_CPU */
};
/* This is called very early during platform setup_arch */
@ -80,4 +152,8 @@ void __init pnv_smp_init(void)
smp_ops->take_timebase = rtas_take_timebase;
}
#endif /* CONFIG_PPC_RTAS */
#ifdef CONFIG_HOTPLUG_CPU
ppc_md.cpu_die = pnv_smp_cpu_kill_self;
#endif
}