qemu/softmmu/cpu-timers.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/cutils.h"
#include "migration/vmstate.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "sysemu/cpus.h"
#include "qemu/main-loop.h"
#include "qemu/option.h"
#include "qemu/seqlock.h"
#include "sysemu/replay.h"
#include "sysemu/runstate.h"
#include "hw/core/cpu.h"
#include "sysemu/cpu-timers.h"
#include "sysemu/cpu-throttle.h"
#include "timers-state.h"
/* clock and ticks */
static int64_t cpu_get_ticks_locked(void)
{
int64_t ticks = timers_state.cpu_ticks_offset;
if (timers_state.cpu_ticks_enabled) {
ticks += cpu_get_host_ticks();
}
if (timers_state.cpu_ticks_prev > ticks) {
/* Non increasing ticks may happen if the host uses software suspend. */
timers_state.cpu_ticks_offset += timers_state.cpu_ticks_prev - ticks;
ticks = timers_state.cpu_ticks_prev;
}
timers_state.cpu_ticks_prev = ticks;
return ticks;
}
/*
* return the time elapsed in VM between vm_start and vm_stop.
* cpu_get_ticks() uses units of the host CPU cycle counter.
*/
int64_t cpu_get_ticks(void)
{
int64_t ticks;
qemu_spin_lock(&timers_state.vm_clock_lock);
ticks = cpu_get_ticks_locked();
qemu_spin_unlock(&timers_state.vm_clock_lock);
return ticks;
}
int64_t cpu_get_clock_locked(void)
{
int64_t time;
time = timers_state.cpu_clock_offset;
if (timers_state.cpu_ticks_enabled) {
time += get_clock();
}
return time;
}
/*
* Return the monotonic time elapsed in VM, i.e.,
* the time between vm_start and vm_stop
*/
int64_t cpu_get_clock(void)
{
int64_t ti;
unsigned start;
do {
start = seqlock_read_begin(&timers_state.vm_clock_seqlock);
ti = cpu_get_clock_locked();
} while (seqlock_read_retry(&timers_state.vm_clock_seqlock, start));
return ti;
}
/*
* enable cpu_get_ticks()
* Caller must hold BQL which serves as mutex for vm_clock_seqlock.
*/
void cpu_enable_ticks(void)
{
seqlock_write_lock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
if (!timers_state.cpu_ticks_enabled) {
timers_state.cpu_ticks_offset -= cpu_get_host_ticks();
timers_state.cpu_clock_offset -= get_clock();
timers_state.cpu_ticks_enabled = 1;
}
seqlock_write_unlock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
}
/*
* disable cpu_get_ticks() : the clock is stopped. You must not call
* cpu_get_ticks() after that.
* Caller must hold BQL which serves as mutex for vm_clock_seqlock.
*/
void cpu_disable_ticks(void)
{
seqlock_write_lock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
if (timers_state.cpu_ticks_enabled) {
timers_state.cpu_ticks_offset += cpu_get_host_ticks();
timers_state.cpu_clock_offset = cpu_get_clock_locked();
timers_state.cpu_ticks_enabled = 0;
}
seqlock_write_unlock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
}
static bool icount_state_needed(void *opaque)
{
return icount_enabled();
}
static bool warp_timer_state_needed(void *opaque)
{
TimersState *s = opaque;
return s->icount_warp_timer != NULL;
}
static bool adjust_timers_state_needed(void *opaque)
{
TimersState *s = opaque;
return s->icount_rt_timer != NULL;
}
static bool icount_shift_state_needed(void *opaque)
{
return icount_enabled() == 2;
}
/*
* Subsection for warp timer migration is optional, because may not be created
*/
static const VMStateDescription icount_vmstate_warp_timer = {
.name = "timer/icount/warp_timer",
.version_id = 1,
.minimum_version_id = 1,
.needed = warp_timer_state_needed,
.fields = (VMStateField[]) {
VMSTATE_INT64(vm_clock_warp_start, TimersState),
VMSTATE_TIMER_PTR(icount_warp_timer, TimersState),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription icount_vmstate_adjust_timers = {
.name = "timer/icount/timers",
.version_id = 1,
.minimum_version_id = 1,
.needed = adjust_timers_state_needed,
.fields = (VMStateField[]) {
VMSTATE_TIMER_PTR(icount_rt_timer, TimersState),
VMSTATE_TIMER_PTR(icount_vm_timer, TimersState),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription icount_vmstate_shift = {
.name = "timer/icount/shift",
.version_id = 2,
.minimum_version_id = 2,
.needed = icount_shift_state_needed,
.fields = (VMStateField[]) {
VMSTATE_INT16(icount_time_shift, TimersState),
VMSTATE_INT64(last_delta, TimersState),
VMSTATE_END_OF_LIST()
}
};
/*
* This is a subsection for icount migration.
*/
static const VMStateDescription icount_vmstate_timers = {
.name = "timer/icount",
.version_id = 1,
.minimum_version_id = 1,
.needed = icount_state_needed,
.fields = (VMStateField[]) {
VMSTATE_INT64(qemu_icount_bias, TimersState),
VMSTATE_INT64(qemu_icount, TimersState),
VMSTATE_END_OF_LIST()
},
.subsections = (const VMStateDescription * []) {
&icount_vmstate_warp_timer,
&icount_vmstate_adjust_timers,
&icount_vmstate_shift,
NULL
}
};
static const VMStateDescription vmstate_timers = {
.name = "timer",
.version_id = 2,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_INT64(cpu_ticks_offset, TimersState),
VMSTATE_UNUSED(8),
VMSTATE_INT64_V(cpu_clock_offset, TimersState, 2),
VMSTATE_END_OF_LIST()
},
.subsections = (const VMStateDescription * []) {
&icount_vmstate_timers,
NULL
}
};
static void do_nothing(CPUState *cpu, run_on_cpu_data unused)
{
}
void qemu_timer_notify_cb(void *opaque, QEMUClockType type)
{
if (!icount_enabled() || type != QEMU_CLOCK_VIRTUAL) {
qemu_notify_event();
return;
}
if (qemu_in_vcpu_thread()) {
/*
* A CPU is currently running; kick it back out to the
* tcg_cpu_exec() loop so it will recalculate its
* icount deadline immediately.
*/
qemu_cpu_kick(current_cpu);
} else if (first_cpu) {
/*
* qemu_cpu_kick is not enough to kick a halted CPU out of
* qemu_tcg_wait_io_event. async_run_on_cpu, instead,
* causes cpu_thread_is_idle to return false. This way,
* handle_icount_deadline can run.
* If we have no CPUs at all for some reason, we don't
* need to do anything.
*/
async_run_on_cpu(first_cpu, do_nothing, RUN_ON_CPU_NULL);
}
}
TimersState timers_state;
/* initialize timers state and the cpu throttle for convenience */
void cpu_timers_init(void)
{
seqlock_init(&timers_state.vm_clock_seqlock);
qemu_spin_init(&timers_state.vm_clock_lock);
vmstate_register(NULL, 0, &vmstate_timers, &timers_state);
cpu_throttle_init();
}