aboutsummaryrefslogtreecommitdiff
path: root/arch/i386/kernel/vmitime.c
blob: d21779749838689e7eb4971d83474f8a5fe8f9aa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
/*
 * 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  = {
	vmi_timer_interrupt,
	SA_INTERRUPT,
	CPU_MASK_NONE,
	"VMI-alarm",
	NULL,
	NULL
};

/* 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 __init 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 */