Commit d25bf7e5 authored by Venkatesh Pallipadi's avatar Venkatesh Pallipadi Committed by Linus Torvalds
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[PATCH] x86_64: Handle missing local APIC timer interrupts on C3 state



Whenever we see that a CPU is capable of C3 (during ACPI cstate init), we
disable local APIC timer and switch to using a broadcast from external timer
interrupt (IRQ 0).

Patch below adds the code for x86_64.
Signed-off-by: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 6eb0a0fd
......@@ -25,6 +25,7 @@
#include <linux/mc146818rtc.h>
#include <linux/kernel_stat.h>
#include <linux/sysdev.h>
#include <linux/module.h>
#include <asm/atomic.h>
#include <asm/smp.h>
......@@ -38,6 +39,12 @@ int apic_verbosity;
int disable_apic_timer __initdata;
/*
* cpu_mask that denotes the CPUs that needs timer interrupt coming in as
* IPIs in place of local APIC timers
*/
static cpumask_t timer_interrupt_broadcast_ipi_mask;
/* Using APIC to generate smp_local_timer_interrupt? */
int using_apic_timer = 0;
......@@ -656,9 +663,14 @@ void __init init_apic_mappings(void)
static void __setup_APIC_LVTT(unsigned int clocks)
{
unsigned int lvtt_value, tmp_value, ver;
int cpu = smp_processor_id();
ver = GET_APIC_VERSION(apic_read(APIC_LVR));
lvtt_value = APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
if (cpu_isset(cpu, timer_interrupt_broadcast_ipi_mask))
lvtt_value |= APIC_LVT_MASKED;
apic_write_around(APIC_LVTT, lvtt_value);
/*
......@@ -781,7 +793,7 @@ void __cpuinit setup_secondary_APIC_clock(void)
local_irq_enable();
}
void __cpuinit disable_APIC_timer(void)
void disable_APIC_timer(void)
{
if (using_apic_timer) {
unsigned long v;
......@@ -793,7 +805,10 @@ void __cpuinit disable_APIC_timer(void)
void enable_APIC_timer(void)
{
if (using_apic_timer) {
int cpu = smp_processor_id();
if (using_apic_timer &&
!cpu_isset(cpu, timer_interrupt_broadcast_ipi_mask)) {
unsigned long v;
v = apic_read(APIC_LVTT);
......@@ -801,6 +816,42 @@ void enable_APIC_timer(void)
}
}
void switch_APIC_timer_to_ipi(void *cpumask)
{
cpumask_t mask = *(cpumask_t *)cpumask;
int cpu = smp_processor_id();
if (cpu_isset(cpu, mask) &&
!cpu_isset(cpu, timer_interrupt_broadcast_ipi_mask)) {
disable_APIC_timer();
cpu_set(cpu, timer_interrupt_broadcast_ipi_mask);
}
}
EXPORT_SYMBOL(switch_APIC_timer_to_ipi);
void smp_send_timer_broadcast_ipi(void)
{
cpumask_t mask;
cpus_and(mask, cpu_online_map, timer_interrupt_broadcast_ipi_mask);
if (!cpus_empty(mask)) {
send_IPI_mask(mask, LOCAL_TIMER_VECTOR);
}
}
void switch_ipi_to_APIC_timer(void *cpumask)
{
cpumask_t mask = *(cpumask_t *)cpumask;
int cpu = smp_processor_id();
if (cpu_isset(cpu, mask) &&
cpu_isset(cpu, timer_interrupt_broadcast_ipi_mask)) {
cpu_clear(cpu, timer_interrupt_broadcast_ipi_mask);
enable_APIC_timer();
}
}
EXPORT_SYMBOL(switch_ipi_to_APIC_timer);
int setup_profiling_timer(unsigned int multiplier)
{
return -EINVAL;
......
......@@ -471,6 +471,11 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
write_sequnlock(&xtime_lock);
#ifdef CONFIG_X86_LOCAL_APIC
if (using_apic_timer)
smp_send_timer_broadcast_ipi();
#endif
return IRQ_HANDLED;
}
......
......@@ -113,6 +113,12 @@ extern int disable_timer_pin_1;
extern void setup_threshold_lvt(unsigned long lvt_off);
void smp_send_timer_broadcast_ipi(void);
void switch_APIC_timer_to_ipi(void *cpumask);
void switch_ipi_to_APIC_timer(void *cpumask);
#define ARCH_APICTIMER_STOPS_ON_C3 1
#endif /* CONFIG_X86_LOCAL_APIC */
extern unsigned boot_cpu_id;
......
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