/*
* VMI paravirtual timer support routines.
*
* Copyright (C) 2005, VMware, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Send feedback to dhecht@vmware.com
*
*/
/*
* Portions of this code from arch/i386/kernel/timers/timer_tsc.c.
* Portions of the CONFIG_NO_IDLE_HZ code from arch/s390/kernel/time.c.
* See comments there for proper credits.
*/
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/rcupdate.h>
#include <linux/clocksource.h>
#include <asm/timer.h>
#include <asm/io.h>
#include <asm/apic.h>
#include <asm/div64.h>
#include <asm/timer.h>
#include <asm/desc.h>
#include <asm/vmi.h>
#include <asm/vmi_time.h>
#include <mach_timer.h>
#include <io_ports.h>
#ifdef CONFIG_X86_LOCAL_APIC
#define VMI_ALARM_WIRING VMI_ALARM_WIRED_LVTT
#else
#define VMI_ALARM_WIRING VMI_ALARM_WIRED_IRQ0
#endif
/* Cached VMI operations */
struct vmi_timer_ops vmi_timer_ops;
#ifdef CONFIG_NO_IDLE_HZ
/* /proc/sys/kernel/hz_timer state. */
int sysctl_hz_timer;
/* Some stats */
static DEFINE_PER_CPU(unsigned long, vmi_idle_no_hz_irqs);
static DEFINE_PER_CPU(unsigned long, vmi_idle_no_hz_jiffies);
static DEFINE_PER_CPU(unsigned long, idle_start_jiffies);
#endif /* CONFIG_NO_IDLE_HZ */
/* Number of alarms per second. By default this is CONFIG_VMI_ALARM_HZ. */
static int alarm_hz = CONFIG_VMI_ALARM_HZ;
/* Cache of the value get_cycle_frequency / HZ. */
static signed long long cycles_per_jiffy;
/* Cache of the value get_cycle_frequency / alarm_hz. */
static signed long long cycles_per_alarm;
/* The number of cycles accounted for by the 'jiffies'/'xtime' count.
* Protected by xtime_lock. */
static unsigned long long real_cycles_accounted_system;
/* The number of cycles accounted for by update_process_times(), per cpu. */
static DEFINE_PER_CPU(unsigned long long, process_times_cycles_accounted_cpu);
/* The number of stolen cycles accounted, per cpu. */
static DEFINE_PER_CPU(unsigned long long, stolen_cycles_accounted_cpu);
/* Clock source. */
static cycle_t read_real_cycles(void)
{
return vmi_timer_ops.get_cycle_counter(VMI_CYCLES_REAL);
}
static cycle_t read_available_cycles(void)
{
return vmi_timer_ops.get_cycle_counter(VMI_CYCLES_AVAILABLE);
}
#if 0
static cycle_t read_stolen_cycles(void)
{
return vmi_timer_ops.get_cycle_counter(VMI_CYCLES_STOLEN);
}
#endif /* 0 */
static struct clocksource clocksource_vmi = {
.name = "vmi-timer",
.rating = 450,
.read = read_real_cycles,
.mask = CLOCKSOURCE_MASK(64),
.mult = 0, /* to be set */
.shift = 22,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/* Timer interrupt handler. */
static irqreturn_t vmi_timer_interrupt(int irq, void *dev_id);
static struct irqaction vmi_timer_irq = {
.handler = vmi_timer_interrupt,
.flags = IRQF_DISABLED,
.mask = CPU_MASK_NONE,
.name = "VMI-alarm",
};
/* Alarm rate */
static int __init vmi_timer_alarm_rate_setup(char* str)
{
int alarm_rate;
if (get_option(&str, &alarm_rate) == 1 && alarm_rate > 0) {
alarm_hz = alarm_rate;
printk(KERN_WARNING "VMI timer alarm HZ set to %d\n", alarm_hz);
}
return 1;
}
__setup("vmi_timer_alarm_hz=", vmi_timer_alarm_rate_setup);
/* Initialization */
static void vmi_get_wallclock_ts(struct timespec *ts)
{
unsigned long long wallclock;
wallclock = vmi_timer_ops.get_wallclock(); // nsec units
ts->tv_nsec = do_div(wallclock, 1000000000);
ts->tv_sec = wallclock;
}
unsigned long vmi_get_wallclock(void)
{
struct timespec ts;
vmi_get_wallclock_ts(&ts);
return ts.tv_sec;
}
int vmi_set_wallclock(unsigned long now)
{
return -1;
}
unsigned long long vmi_get_sched_cycles(void)
{
return read_available_cycles();
}
unsigned long vmi_cpu_khz(void)
{
unsigned long long khz;
khz = vmi_timer_ops.get_cycle_frequency();
(void)do_div(khz, 1000);
return khz;
}
void __init vmi_time_init(void)
{
unsigned long long cycles_per_sec, cycles_per_msec;
unsigned long flags;
local_irq_save(flags);
setup_irq(0, &vmi_timer_irq);
#ifdef CONFIG_X86_LOCAL_APIC
set_intr_gate(LOCAL_TIMER_VECTOR, apic_vmi_timer_interrupt);
#endif
real_cycles_accounted_system = read_real_cycles();
per_cpu(process_times_cycles_accounted_cpu, 0) = read_available_cycles();
cycles_per_sec = vmi_timer_ops.get_cycle_frequency();
cycles_per_jiffy = cycles_per_sec;
(void)do_div(cycles_per_jiffy, HZ);
cycles_per_alarm = cycles_per_sec;
(void)do_div(cycles_per_alarm, alarm_hz);
cycles_per_msec = cycles_per_sec;
(void)do_div(cycles_per_msec, 1000);
printk(KERN_WARNING "VMI timer cycles/sec = %llu ; cycles/jiffy = %llu ;"
"cycles/alarm = %llu\n", cycles_per_sec, cycles_per_jiffy,
cycles_per_alarm);
clocksource_vmi.mult = clocksource_khz2mult(cycles_per_msec,
clocksource_vmi.shift);
if (clocksource_register(&clocksource_vmi))
printk(KERN_WARNING "Error registering VMITIME clocksource.");
/* Disable PIT. */
outb_p(0x3a, PIT_MODE); /* binary, mode 5, LSB/MSB, ch 0 */
/* schedule the alarm. do this in phase with process_times_cycles_accounted_cpu
* reduce the latency calling update_process_times. */
vmi_timer_ops.set_alarm(
VMI_ALARM_WIRED_IRQ0 | VMI_ALARM_IS_PERIODIC | VMI_CYCLES_AVAILABLE,
per_cpu(process_times_cycles_accounted_cpu, 0) + cycles_per_alarm,
cycles_per_alarm);
local_irq_restore(flags);
}
#ifdef CONFIG_X86_LOCAL_APIC
void __init vmi_timer_setup_boot_alarm(void)
{
local_irq_disable();
/* Route the interrupt to the correct vector. */
apic_write_around(APIC_LVTT, LOCAL_TIMER_VECTOR);
/* Cancel the IRQ0 wired alarm, and setup the LVTT alarm. */
vmi_timer_ops.cancel_alarm(VMI_CYCLES_AVAILABLE);
vmi_timer_ops.set_alarm(
VMI_ALARM_WIRED_LVTT | VMI_ALARM_IS_PERIODIC | VMI_CYCLES_AVAILABLE,
per_cpu(process_times_cycles_accounted_cpu, 0) + cycles_per_alarm,
cycles_per_alarm);
local_irq_enable();
}
/* Initialize the time accounting variables for an AP on an SMP system.
* Also, set the local alarm for the AP. */
void __devinit vmi_timer_setup_secondary_alarm(void)
{
int cpu = smp_processor_id();
/* Route the interrupt to the correct vector. */
apic_write_around(APIC_LVTT, LOCAL_TIMER_VECTOR);
per_cpu(process_times_cycles_accounted_cpu, cpu) = read_available_cycles();
vmi_timer_ops.set_alarm(
VMI_ALARM_WIRED_LVTT | VMI_ALARM_IS_PERIODIC | VMI_CYCLES_AVAILABLE,
per_cpu(process_times_cycles_accounted_cpu, cpu) + cycles_per_alarm,
cycles_per_alarm);
}
#endif
/* Update system wide (real) time accounting (e.g. jiffies, xtime). */
static void vmi_account_real_cycles(unsigned long long cur_real_cycles)
{
long long cycles_not_accounted;
write_seqlock(&xtime_lock);
cycles_not_accounted = cur_real_cycles - real_cycles_accounted_system;
while (cycles_not_accounted >= cycles_per_jiffy) {
/* systems wide jiffies. */
do_timer(1);
cycles_not_accounted -= cycles_per_jiffy;
real_cycles_accounted_system += cycles_per_jiffy;
}
write_sequnlock(&xtime_lock);
}
/* Update per-cpu process times. */
static void vmi_account_process_times_cycles(struct pt_regs *regs, int cpu,
unsigned long long cur_process_times_cycles)
{
long long cycles_not_accounted;
cycles_not_accounted = cur_process_times_cycles -
per_cpu(process_times_cycles_accounted_cpu, cpu);
while (cycles_not_accounted >= cycles_per_jiffy) {
/* Account time to the current process. This includes
* calling into the scheduler to decrement the timeslice
* and possibly reschedule.*/
update_process_times(user_mode(regs));
/* XXX handle /proc/profile multiplier. */
profile_tick(CPU_PROFILING);
cycles_not_accounted -= cycles_per_jiffy;
per_cpu(process_times_cycles_accounted_cpu, cpu) += cycles_per_jiffy;
}
}
#ifdef CONFIG_NO_IDLE_HZ
/* Update per-cpu idle times. Used when a no-hz halt is ended. */
static void vmi_account_no_hz_idle_cycles(int cpu,
unsigned long long cur_process_times_cycles)
{
long long cycles_not_accounted;
unsigned long no_idle_hz_jiffies = 0;
cycles_not_accounted = cur_process_times_cycles -
per_cpu(process_times_cycles_accounted_cpu, cpu);
while (cycles_not_accounted >= cycles_per_jiffy) {
no_idle_hz_jiffies++;
cycles_not_accounted -= cycles_per_jiffy;
per_cpu(process_times_cycles_accounted_cpu, cpu) += cycles_per_jiffy;
}
/* Account time to the idle process. */
account_steal_time(idle_task(cpu), jiffies_to_cputime(no_idle_hz_jiffies));
}
#endif
/* Update per-cpu stolen time. */
static void vmi_account_stolen_cycles(int cpu,
unsigned long long cur_real_cycles,
unsigned long long cur_avail_cycles)
{
long long stolen_cycles_not_accounted;
unsigned long stolen_jiffies = 0;
if (cur_real_cycles < cur_avail_cycles)
return;
stolen_cycles_not_accounted = cur_real_cycles - cur_avail_cycles -
per_cpu(stolen_cycles_accounted_cpu, cpu);
while (stolen_cycles_not_accounted >= cycles_per_jiffy) {
stolen_jiffies++;
stolen_cycles_not_accounted -= cycles_per_jiffy;
per_cpu(stolen_cycles_accounted_cpu, cpu) += cycles_per_jiffy;
}
/* HACK: pass NULL to force time onto cpustat->steal. */
account_steal_time(NULL, jiffies_to_cputime(stolen_jiffies));
}
/* Body of either IRQ0 interrupt handler (UP no local-APIC) or
* local-APIC LVTT interrupt handler (UP & local-APIC or SMP). */
static void vmi_local_timer_interrupt(int cpu)
{
unsigned long long cur_real_cycles, cur_process_times_cycles;
cur_real_cycles = read_real_cycles();
cur_process_times_cycles = read_available_cycles();
/* Update system wide (real) time state (xtime, jiffies). */
vmi_account_real_cycles(cur_real_cycles);
/* Update per-cpu process times. */
vmi_account_process_times_cycles(get_irq_regs(), cpu, cur_process_times_cycles);
/* Update time stolen from this cpu by the hypervisor. */
vmi_account_stolen_cycles(cpu, cur_real_cycles, cur_process_times_cycles);
}
#ifdef CONFIG_NO_IDLE_HZ
/* Must be called only from idle loop, with interrupts disabled. */
int vmi_stop_hz_timer(void)
{
/* Note that cpu_set, cpu_clear are (SMP safe) atomic on x86. */
unsigned long seq, next;
unsigned long long real_cycles_expiry;
int cpu = smp_processor_id();
BUG_ON(!irqs_disabled());
if (sysctl_hz_timer != 0)
return 0;
cpu_set(cpu, nohz_cpu_mask);
smp_mb();
if (rcu_needs_cpu(cpu) || local_softirq_pending() ||
(next = next_timer_interrupt(),
time_before_eq(next, jiffies + HZ/CONFIG_VMI_ALARM_HZ))) {
cpu_clear(cpu, nohz_cpu_mask);
return 0;
}
/* Convert jiffies to the real cycle counter. */
do {
seq = read_seqbegin(&xtime_lock);
real_cycles_expiry = real_cycles_accounted_system +
(long)(next - jiffies) * cycles_per_jiffy;
} while (read_seqretry(&xtime_lock, seq));
/* This cpu is going idle. Disable the periodic alarm. */
vmi_timer_ops.cancel_alarm(VMI_CYCLES_AVAILABLE);
per_cpu(idle_start_jiffies, cpu) = jiffies;
/* Set the real time alarm to expire at the next event. */
vmi_timer_ops.set_alarm(
VMI_ALARM_WIRING | VMI_ALARM_IS_ONESHOT | VMI_CYCLES_REAL,
real_cycles_expiry, 0);
return 1;
}
static void vmi_reenable_hz_timer(int cpu)
{
/* For /proc/vmi/info idle_hz stat. */
per_cpu(vmi_idle_no_hz_jiffies, cpu) += jiffies - per_cpu(idle_start_jiffies, cpu);
per_cpu(vmi_idle_no_hz_irqs, cpu)++;
/* Don't bother explicitly cancelling the one-shot alarm -- at
* worse we will receive a spurious timer interrupt. */
vmi_timer_ops.set_alarm(
VMI_ALARM_WIRING | VMI_ALARM_IS_PERIODIC | VMI_CYCLES_AVAILABLE,
per_cpu(process_times_cycles_accounted_cpu, cpu) + cycles_per_alarm,
cycles_per_alarm);
/* Indicate this cpu is no longer nohz idle. */
cpu_clear(cpu, nohz_cpu_mask);
}
/* Called from interrupt handlers when (local) HZ timer is disabled. */
void vmi_account_time_restart_hz_timer(void)
{
unsigned long long cur_real_cycles, cur_process_times_cycles;
int cpu = smp_processor_id();
BUG_ON(!irqs_disabled());
/* Account the time during which the HZ timer was disabled. */
cur_real_cycles = read_real_cycles();
cur_process_times_cycles = read_available_cycles();
/* Update system wide (real) time state (xtime, jiffies). */
vmi_account_real_cycles(cur_real_cycles);
/* Update per-cpu idle times. */
vmi_account_no_hz_idle_cycles(cpu, cur_process_times_cycles);
/* Update time stolen from this cpu by the hypervisor. */
vmi_account_stolen_cycles(cpu, cur_real_cycles, cur_process_times_cycles);
/* Reenable the hz timer. */
vmi_reenable_hz_timer(cpu);
}
#endif /* CONFIG_NO_IDLE_HZ */
/* UP (and no local-APIC) VMI-timer alarm interrupt handler.
* Handler for IRQ0. Not used when SMP or X86_LOCAL_APIC after
* APIC setup and setup_boot_vmi_alarm() is called. */
static irqreturn_t vmi_timer_interrupt(int irq, void *dev_id)
{
vmi_local_timer_interrupt(smp_processor_id());
return IRQ_HANDLED;
}
#ifdef CONFIG_X86_LOCAL_APIC
/* SMP VMI-timer alarm interrupt handler. Handler for LVTT vector.
* Also used in UP when CONFIG_X86_LOCAL_APIC.
* The wrapper code is from arch/i386/kernel/apic.c#smp_apic_timer_interrupt. */
void smp_apic_vmi_timer_interrupt(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
int cpu = smp_processor_id();
/*
* the NMI deadlock-detector uses this.
*/
per_cpu(irq_stat,cpu).apic_timer_irqs++;
/*
* NOTE! We'd better ACK the irq immediately,
* because timer handling can be slow.
*/
ack_APIC_irq();
/*
* update_process_times() expects us to have done irq_enter().
* Besides, if we don't timer interrupts ignore the global
* interrupt lock, which is the WrongThing (tm) to do.
*/
irq_enter();
vmi_local_timer_interrupt(cpu);
irq_exit();
set_irq_regs(old_regs);
}
#endif /* CONFIG_X86_LOCAL_APIC */
