305 lines
8.4 KiB
C
305 lines
8.4 KiB
C
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/*
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* QEMU TCG Single Threaded vCPUs implementation
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*
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* Copyright (c) 2003-2008 Fabrice Bellard
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* Copyright (c) 2014 Red Hat Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu/osdep.h"
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#include "sysemu/tcg.h"
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#include "sysemu/replay.h"
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#include "sysemu/cpu-timers.h"
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#include "qemu/main-loop.h"
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#include "qemu/notify.h"
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#include "qemu/guest-random.h"
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#include "exec/exec-all.h"
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#include "tcg-accel-ops.h"
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#include "tcg-accel-ops-rr.h"
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#include "tcg-accel-ops-icount.h"
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/* Kick all RR vCPUs */
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void rr_kick_vcpu_thread(CPUState *unused)
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{
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CPUState *cpu;
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CPU_FOREACH(cpu) {
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cpu_exit(cpu);
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};
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}
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/*
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* TCG vCPU kick timer
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*
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* The kick timer is responsible for moving single threaded vCPU
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* emulation on to the next vCPU. If more than one vCPU is running a
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* timer event with force a cpu->exit so the next vCPU can get
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* scheduled.
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*
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* The timer is removed if all vCPUs are idle and restarted again once
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* idleness is complete.
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*/
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static QEMUTimer *rr_kick_vcpu_timer;
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static CPUState *rr_current_cpu;
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static inline int64_t rr_next_kick_time(void)
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{
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return qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + TCG_KICK_PERIOD;
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}
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/* Kick the currently round-robin scheduled vCPU to next */
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static void rr_kick_next_cpu(void)
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{
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CPUState *cpu;
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do {
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cpu = qatomic_mb_read(&rr_current_cpu);
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if (cpu) {
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cpu_exit(cpu);
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}
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} while (cpu != qatomic_mb_read(&rr_current_cpu));
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}
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static void rr_kick_thread(void *opaque)
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{
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timer_mod(rr_kick_vcpu_timer, rr_next_kick_time());
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rr_kick_next_cpu();
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}
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static void rr_start_kick_timer(void)
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{
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if (!rr_kick_vcpu_timer && CPU_NEXT(first_cpu)) {
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rr_kick_vcpu_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
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rr_kick_thread, NULL);
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}
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if (rr_kick_vcpu_timer && !timer_pending(rr_kick_vcpu_timer)) {
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timer_mod(rr_kick_vcpu_timer, rr_next_kick_time());
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}
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}
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static void rr_stop_kick_timer(void)
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{
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if (rr_kick_vcpu_timer && timer_pending(rr_kick_vcpu_timer)) {
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timer_del(rr_kick_vcpu_timer);
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}
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}
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static void rr_wait_io_event(void)
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{
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CPUState *cpu;
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while (all_cpu_threads_idle()) {
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rr_stop_kick_timer();
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qemu_cond_wait_iothread(first_cpu->halt_cond);
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}
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rr_start_kick_timer();
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CPU_FOREACH(cpu) {
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qemu_wait_io_event_common(cpu);
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}
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}
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/*
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* Destroy any remaining vCPUs which have been unplugged and have
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* finished running
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*/
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static void rr_deal_with_unplugged_cpus(void)
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{
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CPUState *cpu;
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CPU_FOREACH(cpu) {
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if (cpu->unplug && !cpu_can_run(cpu)) {
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tcg_cpus_destroy(cpu);
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break;
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}
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}
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}
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static void rr_force_rcu(Notifier *notify, void *data)
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{
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rr_kick_next_cpu();
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}
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/*
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* In the single-threaded case each vCPU is simulated in turn. If
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* there is more than a single vCPU we create a simple timer to kick
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* the vCPU and ensure we don't get stuck in a tight loop in one vCPU.
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* This is done explicitly rather than relying on side-effects
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* elsewhere.
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*/
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static void *rr_cpu_thread_fn(void *arg)
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{
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Notifier force_rcu;
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CPUState *cpu = arg;
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g_assert(tcg_enabled());
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tcg_cpu_init_cflags(cpu, false);
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rcu_register_thread();
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force_rcu.notify = rr_force_rcu;
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rcu_add_force_rcu_notifier(&force_rcu);
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tcg_register_thread();
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qemu_mutex_lock_iothread();
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qemu_thread_get_self(cpu->thread);
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cpu->thread_id = qemu_get_thread_id();
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cpu->can_do_io = 1;
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cpu_thread_signal_created(cpu);
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qemu_guest_random_seed_thread_part2(cpu->random_seed);
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/* wait for initial kick-off after machine start */
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while (first_cpu->stopped) {
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qemu_cond_wait_iothread(first_cpu->halt_cond);
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/* process any pending work */
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CPU_FOREACH(cpu) {
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current_cpu = cpu;
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qemu_wait_io_event_common(cpu);
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}
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}
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rr_start_kick_timer();
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cpu = first_cpu;
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/* process any pending work */
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cpu->exit_request = 1;
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while (1) {
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qemu_mutex_unlock_iothread();
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replay_mutex_lock();
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qemu_mutex_lock_iothread();
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if (icount_enabled()) {
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/* Account partial waits to QEMU_CLOCK_VIRTUAL. */
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icount_account_warp_timer();
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/*
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* Run the timers here. This is much more efficient than
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* waking up the I/O thread and waiting for completion.
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*/
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icount_handle_deadline();
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}
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replay_mutex_unlock();
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if (!cpu) {
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cpu = first_cpu;
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}
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while (cpu && cpu_work_list_empty(cpu) && !cpu->exit_request) {
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qatomic_mb_set(&rr_current_cpu, cpu);
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current_cpu = cpu;
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qemu_clock_enable(QEMU_CLOCK_VIRTUAL,
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(cpu->singlestep_enabled & SSTEP_NOTIMER) == 0);
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if (cpu_can_run(cpu)) {
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int r;
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qemu_mutex_unlock_iothread();
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if (icount_enabled()) {
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icount_prepare_for_run(cpu);
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}
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r = tcg_cpus_exec(cpu);
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if (icount_enabled()) {
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icount_process_data(cpu);
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}
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qemu_mutex_lock_iothread();
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if (r == EXCP_DEBUG) {
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cpu_handle_guest_debug(cpu);
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break;
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} else if (r == EXCP_ATOMIC) {
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qemu_mutex_unlock_iothread();
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cpu_exec_step_atomic(cpu);
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qemu_mutex_lock_iothread();
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break;
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}
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} else if (cpu->stop) {
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if (cpu->unplug) {
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cpu = CPU_NEXT(cpu);
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}
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break;
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}
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cpu = CPU_NEXT(cpu);
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} /* while (cpu && !cpu->exit_request).. */
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/* Does not need qatomic_mb_set because a spurious wakeup is okay. */
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qatomic_set(&rr_current_cpu, NULL);
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if (cpu && cpu->exit_request) {
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qatomic_mb_set(&cpu->exit_request, 0);
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}
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if (icount_enabled() && all_cpu_threads_idle()) {
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/*
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* When all cpus are sleeping (e.g in WFI), to avoid a deadlock
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* in the main_loop, wake it up in order to start the warp timer.
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*/
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qemu_notify_event();
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}
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rr_wait_io_event();
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rr_deal_with_unplugged_cpus();
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}
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rcu_remove_force_rcu_notifier(&force_rcu);
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rcu_unregister_thread();
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return NULL;
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}
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void rr_start_vcpu_thread(CPUState *cpu)
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{
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char thread_name[VCPU_THREAD_NAME_SIZE];
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static QemuCond *single_tcg_halt_cond;
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static QemuThread *single_tcg_cpu_thread;
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if (!single_tcg_cpu_thread) {
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cpu->thread = g_new0(QemuThread, 1);
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cpu->halt_cond = g_new0(QemuCond, 1);
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qemu_cond_init(cpu->halt_cond);
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/* share a single thread for all cpus with TCG */
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snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "ALL CPUs/TCG");
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qemu_thread_create(cpu->thread, thread_name,
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rr_cpu_thread_fn,
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cpu, QEMU_THREAD_JOINABLE);
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single_tcg_halt_cond = cpu->halt_cond;
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single_tcg_cpu_thread = cpu->thread;
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#ifdef _WIN32
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cpu->hThread = qemu_thread_get_handle(cpu->thread);
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#endif
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} else {
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/* we share the thread */
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cpu->thread = single_tcg_cpu_thread;
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cpu->halt_cond = single_tcg_halt_cond;
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cpu->thread_id = first_cpu->thread_id;
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cpu->can_do_io = 1;
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cpu->created = true;
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}
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}
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