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qemu/util/qemu-timer.c

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/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qemu/main-loop.h"
#include "qemu/timer.h"
#include "qemu/lockable.h"
#include "sysemu/cpu-timers.h"
#include "sysemu/replay.h"
#include "sysemu/cpus.h"
#ifdef CONFIG_POSIX
#include <pthread.h>
#endif
#ifdef CONFIG_PPOLL
#include <poll.h>
#endif
#ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
#include <sys/prctl.h>
#endif
/***********************************************************/
/* timers */
typedef struct QEMUClock {
/* We rely on BQL to protect the timerlists */
QLIST_HEAD(, QEMUTimerList) timerlists;
QEMUClockType type;
bool enabled;
} QEMUClock;
QEMUTimerListGroup main_loop_tlg;
static QEMUClock qemu_clocks[QEMU_CLOCK_MAX];
/* A QEMUTimerList is a list of timers attached to a clock. More
* than one QEMUTimerList can be attached to each clock, for instance
* used by different AioContexts / threads. Each clock also has
* a list of the QEMUTimerLists associated with it, in order that
* reenabling the clock can call all the notifiers.
*/
struct QEMUTimerList {
QEMUClock *clock;
QemuMutex active_timers_lock;
QEMUTimer *active_timers;
QLIST_ENTRY(QEMUTimerList) list;
QEMUTimerListNotifyCB *notify_cb;
void *notify_opaque;
/* lightweight method to mark the end of timerlist's running */
QemuEvent timers_done_ev;
};
/**
* qemu_clock_ptr:
* @type: type of clock
*
* Translate a clock type into a pointer to QEMUClock object.
*
* Returns: a pointer to the QEMUClock object
*/
static inline QEMUClock *qemu_clock_ptr(QEMUClockType type)
{
return &qemu_clocks[type];
}
static bool timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
{
return timer_head && (timer_head->expire_time <= current_time);
}
QEMUTimerList *timerlist_new(QEMUClockType type,
QEMUTimerListNotifyCB *cb,
void *opaque)
{
QEMUTimerList *timer_list;
QEMUClock *clock = qemu_clock_ptr(type);
timer_list = g_malloc0(sizeof(QEMUTimerList));
qemu_event_init(&timer_list->timers_done_ev, true);
timer_list->clock = clock;
timer_list->notify_cb = cb;
timer_list->notify_opaque = opaque;
qemu_mutex_init(&timer_list->active_timers_lock);
QLIST_INSERT_HEAD(&clock->timerlists, timer_list, list);
return timer_list;
}
void timerlist_free(QEMUTimerList *timer_list)
{
assert(!timerlist_has_timers(timer_list));
if (timer_list->clock) {
QLIST_REMOVE(timer_list, list);
}
qemu_mutex_destroy(&timer_list->active_timers_lock);
g_free(timer_list);
}
static void qemu_clock_init(QEMUClockType type, QEMUTimerListNotifyCB *notify_cb)
{
QEMUClock *clock = qemu_clock_ptr(type);
/* Assert that the clock of type TYPE has not been initialized yet. */
assert(main_loop_tlg.tl[type] == NULL);
clock->type = type;
clock->enabled = (type == QEMU_CLOCK_VIRTUAL ? false : true);
QLIST_INIT(&clock->timerlists);
main_loop_tlg.tl[type] = timerlist_new(type, notify_cb, NULL);
}
bool qemu_clock_use_for_deadline(QEMUClockType type)
{
return !(icount_enabled() && (type == QEMU_CLOCK_VIRTUAL));
}
void qemu_clock_notify(QEMUClockType type)
{
QEMUTimerList *timer_list;
QEMUClock *clock = qemu_clock_ptr(type);
QLIST_FOREACH(timer_list, &clock->timerlists, list) {
timerlist_notify(timer_list);
}
}
/* Disabling the clock will wait for related timerlists to stop
* executing qemu_run_timers. Thus, this functions should not
* be used from the callback of a timer that is based on @clock.
* Doing so would cause a deadlock.
*
* Caller should hold BQL.
*/
void qemu_clock_enable(QEMUClockType type, bool enabled)
{
QEMUClock *clock = qemu_clock_ptr(type);
QEMUTimerList *tl;
bool old = clock->enabled;
clock->enabled = enabled;
if (enabled && !old) {
qemu_clock_notify(type);
} else if (!enabled && old) {
QLIST_FOREACH(tl, &clock->timerlists, list) {
qemu_event_wait(&tl->timers_done_ev);
}
}
}
bool timerlist_has_timers(QEMUTimerList *timer_list)
{
return !!qatomic_read(&timer_list->active_timers);
}
bool qemu_clock_has_timers(QEMUClockType type)
{
return timerlist_has_timers(
main_loop_tlg.tl[type]);
}
bool timerlist_expired(QEMUTimerList *timer_list)
{
int64_t expire_time;
if (!qatomic_read(&timer_list->active_timers)) {
return false;
}
WITH_QEMU_LOCK_GUARD(&timer_list->active_timers_lock) {
if (!timer_list->active_timers) {
return false;
}
expire_time = timer_list->active_timers->expire_time;
}
return expire_time <= qemu_clock_get_ns(timer_list->clock->type);
}
bool qemu_clock_expired(QEMUClockType type)
{
return timerlist_expired(
main_loop_tlg.tl[type]);
}
/*
* As above, but return -1 for no deadline, and do not cap to 2^32
* as we know the result is always positive.
*/
int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
{
int64_t delta;
int64_t expire_time;
if (!qatomic_read(&timer_list->active_timers)) {
return -1;
}
if (!timer_list->clock->enabled) {
return -1;
}
/* The active timers list may be modified before the caller uses our return
* value but ->notify_cb() is called when the deadline changes. Therefore
* the caller should notice the change and there is no race condition.
*/
WITH_QEMU_LOCK_GUARD(&timer_list->active_timers_lock) {
if (!timer_list->active_timers) {
return -1;
}
expire_time = timer_list->active_timers->expire_time;
}
delta = expire_time - qemu_clock_get_ns(timer_list->clock->type);
if (delta <= 0) {
return 0;
}
return delta;
}
/* Calculate the soonest deadline across all timerlists attached
* to the clock. This is used for the icount timeout so we
* ignore whether or not the clock should be used in deadline
* calculations.
*/
int64_t qemu_clock_deadline_ns_all(QEMUClockType type, int attr_mask)
{
int64_t deadline = -1;
int64_t delta;
int64_t expire_time;
QEMUTimer *ts;
QEMUTimerList *timer_list;
QEMUClock *clock = qemu_clock_ptr(type);
if (!clock->enabled) {
return -1;
}
QLIST_FOREACH(timer_list, &clock->timerlists, list) {
qemu_mutex_lock(&timer_list->active_timers_lock);
ts = timer_list->active_timers;
/* Skip all external timers */
while (ts && (ts->attributes & ~attr_mask)) {
ts = ts->next;
}
if (!ts) {
qemu_mutex_unlock(&timer_list->active_timers_lock);
continue;
}
expire_time = ts->expire_time;
qemu_mutex_unlock(&timer_list->active_timers_lock);
delta = expire_time - qemu_clock_get_ns(type);
if (delta <= 0) {
delta = 0;
}
deadline = qemu_soonest_timeout(deadline, delta);
}
return deadline;
}
QEMUClockType timerlist_get_clock(QEMUTimerList *timer_list)
{
return timer_list->clock->type;
}
QEMUTimerList *qemu_clock_get_main_loop_timerlist(QEMUClockType type)
{
return main_loop_tlg.tl[type];
}
void timerlist_notify(QEMUTimerList *timer_list)
{
if (timer_list->notify_cb) {
timer_list->notify_cb(timer_list->notify_opaque, timer_list->clock->type);
} else {
qemu_notify_event();
}
}
/* Transition function to convert a nanosecond timeout to ms
* This is used where a system does not support ppoll
*/
int qemu_timeout_ns_to_ms(int64_t ns)
{
int64_t ms;
if (ns < 0) {
return -1;
}
if (!ns) {
return 0;
}
/* Always round up, because it's better to wait too long than to wait too
* little and effectively busy-wait
*/
ms = DIV_ROUND_UP(ns, SCALE_MS);
/* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */
return MIN(ms, INT32_MAX);
}
/* qemu implementation of g_poll which uses a nanosecond timeout but is
* otherwise identical to g_poll
*/
int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
{
#ifdef CONFIG_PPOLL
if (timeout < 0) {
return ppoll((struct pollfd *)fds, nfds, NULL, NULL);
} else {
struct timespec ts;
int64_t tvsec = timeout / 1000000000LL;
/* Avoid possibly overflowing and specifying a negative number of
* seconds, which would turn a very long timeout into a busy-wait.
*/
if (tvsec > (int64_t)INT32_MAX) {
tvsec = INT32_MAX;
}
ts.tv_sec = tvsec;
ts.tv_nsec = timeout % 1000000000LL;
return ppoll((struct pollfd *)fds, nfds, &ts, NULL);
}
#else
return g_poll(fds, nfds, qemu_timeout_ns_to_ms(timeout));
#endif
}
void timer_init_full(QEMUTimer *ts,
QEMUTimerListGroup *timer_list_group, QEMUClockType type,
int scale, int attributes,
QEMUTimerCB *cb, void *opaque)
{
if (!timer_list_group) {
timer_list_group = &main_loop_tlg;
}
ts->timer_list = timer_list_group->tl[type];
ts->cb = cb;
ts->opaque = opaque;
ts->scale = scale;
ts->attributes = attributes;
ts->expire_time = -1;
}
void timer_deinit(QEMUTimer *ts)
{
assert(ts->expire_time == -1);
ts->timer_list = NULL;
}
static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
{
QEMUTimer **pt, *t;
ts->expire_time = -1;
pt = &timer_list->active_timers;
for(;;) {
t = *pt;
if (!t)
break;
if (t == ts) {
qatomic_set(pt, t->next);
break;
}
pt = &t->next;
}
}
static bool timer_mod_ns_locked(QEMUTimerList *timer_list,
QEMUTimer *ts, int64_t expire_time)
{
QEMUTimer **pt, *t;
/* add the timer in the sorted list */
pt = &timer_list->active_timers;
for (;;) {
t = *pt;
if (!timer_expired_ns(t, expire_time)) {
break;
}
pt = &t->next;
}
ts->expire_time = MAX(expire_time, 0);
ts->next = *pt;
qatomic_set(pt, ts);
return pt == &timer_list->active_timers;
}
static void timerlist_rearm(QEMUTimerList *timer_list)
{
/* Interrupt execution to force deadline recalculation. */
if (icount_enabled() && timer_list->clock->type == QEMU_CLOCK_VIRTUAL) {
icount_start_warp_timer();
}
timerlist_notify(timer_list);
}
/* stop a timer, but do not dealloc it */
void timer_del(QEMUTimer *ts)
{
QEMUTimerList *timer_list = ts->timer_list;
if (timer_list) {
qemu_mutex_lock(&timer_list->active_timers_lock);
timer_del_locked(timer_list, ts);
qemu_mutex_unlock(&timer_list->active_timers_lock);
}
}
/* modify the current timer so that it will be fired when current_time
>= expire_time. The corresponding callback will be called. */
void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
{
QEMUTimerList *timer_list = ts->timer_list;
bool rearm;
qemu_mutex_lock(&timer_list->active_timers_lock);
timer_del_locked(timer_list, ts);
rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
qemu_mutex_unlock(&timer_list->active_timers_lock);
if (rearm) {
timerlist_rearm(timer_list);
}
}
/* modify the current timer so that it will be fired when current_time
>= expire_time or the current deadline, whichever comes earlier.
The corresponding callback will be called. */
void timer_mod_anticipate_ns(QEMUTimer *ts, int64_t expire_time)
{
QEMUTimerList *timer_list = ts->timer_list;
bool rearm;
WITH_QEMU_LOCK_GUARD(&timer_list->active_timers_lock) {
if (ts->expire_time == -1 || ts->expire_time > expire_time) {
if (ts->expire_time != -1) {
timer_del_locked(timer_list, ts);
}
rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
} else {
rearm = false;
}
}
if (rearm) {
timerlist_rearm(timer_list);
}
}
void timer_mod(QEMUTimer *ts, int64_t expire_time)
{
timer_mod_ns(ts, expire_time * ts->scale);
}
void timer_mod_anticipate(QEMUTimer *ts, int64_t expire_time)
{
timer_mod_anticipate_ns(ts, expire_time * ts->scale);
}
bool timer_pending(QEMUTimer *ts)
{
return ts->expire_time >= 0;
}
bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
{
return timer_expired_ns(timer_head, current_time * timer_head->scale);
}
bool timerlist_run_timers(QEMUTimerList *timer_list)
{
QEMUTimer *ts;
int64_t current_time;
bool progress = false;
QEMUTimerCB *cb;
void *opaque;
if (!qatomic_read(&timer_list->active_timers)) {
return false;
}
qemu_event_reset(&timer_list->timers_done_ev);
if (!timer_list->clock->enabled) {
goto out;
}
switch (timer_list->clock->type) {
case QEMU_CLOCK_REALTIME:
break;
default:
case QEMU_CLOCK_VIRTUAL:
break;
case QEMU_CLOCK_HOST:
if (!replay_checkpoint(CHECKPOINT_CLOCK_HOST)) {
goto out;
}
break;
case QEMU_CLOCK_VIRTUAL_RT:
if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL_RT)) {
goto out;
}
break;
}
/*
* Extract expired timers from active timers list and process them.
*
* In rr mode we need "filtered" checkpointing for virtual clock. The
* checkpoint must be recorded/replayed before processing any non-EXTERNAL timer,
* and that must only be done once since the clock value stays the same. Because
* non-EXTERNAL timers may appear in the timers list while it being processed,
* the checkpoint can be issued at a time until no timers are left and we are
* done".
*/
current_time = qemu_clock_get_ns(timer_list->clock->type);
qemu_mutex_lock(&timer_list->active_timers_lock);
while ((ts = timer_list->active_timers)) {
if (!timer_expired_ns(ts, current_time)) {
/* No expired timers left. The checkpoint can be skipped
* if no timers fired or they were all external.
*/
break;
}
/* Checkpoint for virtual clock is redundant in cases where
* it's being triggered with only non-EXTERNAL timers, because
* these timers don't change guest state directly.
*/
if (replay_mode != REPLAY_MODE_NONE
&& timer_list->clock->type == QEMU_CLOCK_VIRTUAL
&& !(ts->attributes & QEMU_TIMER_ATTR_EXTERNAL)
&& !replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) {
qemu_mutex_unlock(&timer_list->active_timers_lock);
goto out;
}
/* remove timer from the list before calling the callback */
timer_list->active_timers = ts->next;
ts->next = NULL;
ts->expire_time = -1;
cb = ts->cb;
opaque = ts->opaque;
/* run the callback (the timer list can be modified) */
qemu_mutex_unlock(&timer_list->active_timers_lock);
cb(opaque);
qemu_mutex_lock(&timer_list->active_timers_lock);
progress = true;
}
qemu_mutex_unlock(&timer_list->active_timers_lock);
out:
qemu_event_set(&timer_list->timers_done_ev);
return progress;
}
bool qemu_clock_run_timers(QEMUClockType type)
{
return timerlist_run_timers(main_loop_tlg.tl[type]);
}
void timerlistgroup_init(QEMUTimerListGroup *tlg,
QEMUTimerListNotifyCB *cb, void *opaque)
{
QEMUClockType type;
for (type = 0; type < QEMU_CLOCK_MAX; type++) {
tlg->tl[type] = timerlist_new(type, cb, opaque);
}
}
void timerlistgroup_deinit(QEMUTimerListGroup *tlg)
{
QEMUClockType type;
for (type = 0; type < QEMU_CLOCK_MAX; type++) {
timerlist_free(tlg->tl[type]);
}
}
bool timerlistgroup_run_timers(QEMUTimerListGroup *tlg)
{
QEMUClockType type;
bool progress = false;
for (type = 0; type < QEMU_CLOCK_MAX; type++) {
progress |= timerlist_run_timers(tlg->tl[type]);
}
return progress;
}
int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
{
int64_t deadline = -1;
QEMUClockType type;
for (type = 0; type < QEMU_CLOCK_MAX; type++) {
if (qemu_clock_use_for_deadline(type)) {
deadline = qemu_soonest_timeout(deadline,
timerlist_deadline_ns(tlg->tl[type]));
}
}
return deadline;
}
int64_t qemu_clock_get_ns(QEMUClockType type)
{
switch (type) {
case QEMU_CLOCK_REALTIME:
return get_clock();
default:
case QEMU_CLOCK_VIRTUAL:
return cpus_get_virtual_clock();
case QEMU_CLOCK_HOST:
return REPLAY_CLOCK(REPLAY_CLOCK_HOST, get_clock_realtime());
case QEMU_CLOCK_VIRTUAL_RT:
return REPLAY_CLOCK(REPLAY_CLOCK_VIRTUAL_RT, cpu_get_clock());
}
}
void init_clocks(QEMUTimerListNotifyCB *notify_cb)
{
QEMUClockType type;
for (type = 0; type < QEMU_CLOCK_MAX; type++) {
qemu_clock_init(type, notify_cb);
}
#ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
#endif
}
uint64_t timer_expire_time_ns(QEMUTimer *ts)
{
return timer_pending(ts) ? ts->expire_time : -1;
}
bool qemu_clock_run_all_timers(void)
{
bool progress = false;
QEMUClockType type;
for (type = 0; type < QEMU_CLOCK_MAX; type++) {
if (qemu_clock_use_for_deadline(type)) {
progress |= qemu_clock_run_timers(type);
}
}
return progress;
}
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