qemu/softmmu/cpus.c
Idan Horowitz 25e82fb769 softmmu/cpus: Check if the cpu work list is empty atomically
Instead of taking the lock of the cpu work list in order to check if it's
empty, we can just read the head pointer atomically. This decreases
cpu_work_list_empty's share from 5% to 1.3% in a profile of icount-enabled
aarch64-softmmu.

Signed-off-by: Idan Horowitz <idan.horowitz@gmail.com>
Message-Id: <20220114004358.299534-1-idan.horowitz@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-02-09 08:55:02 +11:00

810 lines
18 KiB
C

/*
* 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-common.h"
#include "monitor/monitor.h"
#include "qapi/error.h"
#include "qapi/qapi-commands-machine.h"
#include "qapi/qapi-commands-misc.h"
#include "qapi/qapi-events-run-state.h"
#include "qapi/qmp/qerror.h"
#include "exec/gdbstub.h"
#include "sysemu/hw_accel.h"
#include "exec/exec-all.h"
#include "qemu/thread.h"
#include "qemu/plugin.h"
#include "sysemu/cpus.h"
#include "qemu/guest-random.h"
#include "hw/nmi.h"
#include "sysemu/replay.h"
#include "sysemu/runstate.h"
#include "sysemu/cpu-timers.h"
#include "sysemu/whpx.h"
#include "hw/boards.h"
#include "hw/hw.h"
#include "trace.h"
#ifdef CONFIG_LINUX
#include <sys/prctl.h>
#ifndef PR_MCE_KILL
#define PR_MCE_KILL 33
#endif
#ifndef PR_MCE_KILL_SET
#define PR_MCE_KILL_SET 1
#endif
#ifndef PR_MCE_KILL_EARLY
#define PR_MCE_KILL_EARLY 1
#endif
#endif /* CONFIG_LINUX */
static QemuMutex qemu_global_mutex;
bool cpu_is_stopped(CPUState *cpu)
{
return cpu->stopped || !runstate_is_running();
}
bool cpu_work_list_empty(CPUState *cpu)
{
return QSIMPLEQ_EMPTY_ATOMIC(&cpu->work_list);
}
bool cpu_thread_is_idle(CPUState *cpu)
{
if (cpu->stop || !cpu_work_list_empty(cpu)) {
return false;
}
if (cpu_is_stopped(cpu)) {
return true;
}
if (!cpu->halted || cpu_has_work(cpu) ||
kvm_halt_in_kernel() || whpx_apic_in_platform()) {
return false;
}
return true;
}
bool all_cpu_threads_idle(void)
{
CPUState *cpu;
CPU_FOREACH(cpu) {
if (!cpu_thread_is_idle(cpu)) {
return false;
}
}
return true;
}
/***********************************************************/
void hw_error(const char *fmt, ...)
{
va_list ap;
CPUState *cpu;
va_start(ap, fmt);
fprintf(stderr, "qemu: hardware error: ");
vfprintf(stderr, fmt, ap);
fprintf(stderr, "\n");
CPU_FOREACH(cpu) {
fprintf(stderr, "CPU #%d:\n", cpu->cpu_index);
cpu_dump_state(cpu, stderr, CPU_DUMP_FPU);
}
va_end(ap);
abort();
}
/*
* The chosen accelerator is supposed to register this.
*/
static const AccelOpsClass *cpus_accel;
void cpu_synchronize_all_states(void)
{
CPUState *cpu;
CPU_FOREACH(cpu) {
cpu_synchronize_state(cpu);
}
}
void cpu_synchronize_all_post_reset(void)
{
CPUState *cpu;
CPU_FOREACH(cpu) {
cpu_synchronize_post_reset(cpu);
}
}
void cpu_synchronize_all_post_init(void)
{
CPUState *cpu;
CPU_FOREACH(cpu) {
cpu_synchronize_post_init(cpu);
}
}
void cpu_synchronize_all_pre_loadvm(void)
{
CPUState *cpu;
CPU_FOREACH(cpu) {
cpu_synchronize_pre_loadvm(cpu);
}
}
void cpu_synchronize_state(CPUState *cpu)
{
if (cpus_accel->synchronize_state) {
cpus_accel->synchronize_state(cpu);
}
}
void cpu_synchronize_post_reset(CPUState *cpu)
{
if (cpus_accel->synchronize_post_reset) {
cpus_accel->synchronize_post_reset(cpu);
}
}
void cpu_synchronize_post_init(CPUState *cpu)
{
if (cpus_accel->synchronize_post_init) {
cpus_accel->synchronize_post_init(cpu);
}
}
void cpu_synchronize_pre_loadvm(CPUState *cpu)
{
if (cpus_accel->synchronize_pre_loadvm) {
cpus_accel->synchronize_pre_loadvm(cpu);
}
}
bool cpus_are_resettable(void)
{
return cpu_check_are_resettable();
}
int64_t cpus_get_virtual_clock(void)
{
/*
* XXX
*
* need to check that cpus_accel is not NULL, because qcow2 calls
* qemu_get_clock_ns(CLOCK_VIRTUAL) without any accel initialized and
* with ticks disabled in some io-tests:
* 030 040 041 060 099 120 127 140 156 161 172 181 191 192 195 203 229 249 256 267
*
* is this expected?
*
* XXX
*/
if (cpus_accel && cpus_accel->get_virtual_clock) {
return cpus_accel->get_virtual_clock();
}
return cpu_get_clock();
}
/*
* return the time elapsed in VM between vm_start and vm_stop. Unless
* icount is active, cpus_get_elapsed_ticks() uses units of the host CPU cycle
* counter.
*/
int64_t cpus_get_elapsed_ticks(void)
{
if (cpus_accel->get_elapsed_ticks) {
return cpus_accel->get_elapsed_ticks();
}
return cpu_get_ticks();
}
static void generic_handle_interrupt(CPUState *cpu, int mask)
{
cpu->interrupt_request |= mask;
if (!qemu_cpu_is_self(cpu)) {
qemu_cpu_kick(cpu);
}
}
void cpu_interrupt(CPUState *cpu, int mask)
{
if (cpus_accel->handle_interrupt) {
cpus_accel->handle_interrupt(cpu, mask);
} else {
generic_handle_interrupt(cpu, mask);
}
}
static int do_vm_stop(RunState state, bool send_stop)
{
int ret = 0;
if (runstate_is_running()) {
runstate_set(state);
cpu_disable_ticks();
pause_all_vcpus();
vm_state_notify(0, state);
if (send_stop) {
qapi_event_send_stop();
}
}
bdrv_drain_all();
ret = bdrv_flush_all();
trace_vm_stop_flush_all(ret);
return ret;
}
/* Special vm_stop() variant for terminating the process. Historically clients
* did not expect a QMP STOP event and so we need to retain compatibility.
*/
int vm_shutdown(void)
{
return do_vm_stop(RUN_STATE_SHUTDOWN, false);
}
bool cpu_can_run(CPUState *cpu)
{
if (cpu->stop) {
return false;
}
if (cpu_is_stopped(cpu)) {
return false;
}
return true;
}
void cpu_handle_guest_debug(CPUState *cpu)
{
if (replay_running_debug()) {
if (!cpu->singlestep_enabled) {
/*
* Report about the breakpoint and
* make a single step to skip it
*/
replay_breakpoint();
cpu_single_step(cpu, SSTEP_ENABLE);
} else {
cpu_single_step(cpu, 0);
}
} else {
gdb_set_stop_cpu(cpu);
qemu_system_debug_request();
cpu->stopped = true;
}
}
#ifdef CONFIG_LINUX
static void sigbus_reraise(void)
{
sigset_t set;
struct sigaction action;
memset(&action, 0, sizeof(action));
action.sa_handler = SIG_DFL;
if (!sigaction(SIGBUS, &action, NULL)) {
raise(SIGBUS);
sigemptyset(&set);
sigaddset(&set, SIGBUS);
pthread_sigmask(SIG_UNBLOCK, &set, NULL);
}
perror("Failed to re-raise SIGBUS!");
abort();
}
static void sigbus_handler(int n, siginfo_t *siginfo, void *ctx)
{
if (siginfo->si_code != BUS_MCEERR_AO && siginfo->si_code != BUS_MCEERR_AR) {
sigbus_reraise();
}
if (current_cpu) {
/* Called asynchronously in VCPU thread. */
if (kvm_on_sigbus_vcpu(current_cpu, siginfo->si_code, siginfo->si_addr)) {
sigbus_reraise();
}
} else {
/* Called synchronously (via signalfd) in main thread. */
if (kvm_on_sigbus(siginfo->si_code, siginfo->si_addr)) {
sigbus_reraise();
}
}
}
static void qemu_init_sigbus(void)
{
struct sigaction action;
/*
* ALERT: when modifying this, take care that SIGBUS forwarding in
* os_mem_prealloc() will continue working as expected.
*/
memset(&action, 0, sizeof(action));
action.sa_flags = SA_SIGINFO;
action.sa_sigaction = sigbus_handler;
sigaction(SIGBUS, &action, NULL);
prctl(PR_MCE_KILL, PR_MCE_KILL_SET, PR_MCE_KILL_EARLY, 0, 0);
}
#else /* !CONFIG_LINUX */
static void qemu_init_sigbus(void)
{
}
#endif /* !CONFIG_LINUX */
static QemuThread io_thread;
/* cpu creation */
static QemuCond qemu_cpu_cond;
/* system init */
static QemuCond qemu_pause_cond;
void qemu_init_cpu_loop(void)
{
qemu_init_sigbus();
qemu_cond_init(&qemu_cpu_cond);
qemu_cond_init(&qemu_pause_cond);
qemu_mutex_init(&qemu_global_mutex);
qemu_thread_get_self(&io_thread);
}
void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
{
do_run_on_cpu(cpu, func, data, &qemu_global_mutex);
}
static void qemu_cpu_stop(CPUState *cpu, bool exit)
{
g_assert(qemu_cpu_is_self(cpu));
cpu->stop = false;
cpu->stopped = true;
if (exit) {
cpu_exit(cpu);
}
qemu_cond_broadcast(&qemu_pause_cond);
}
void qemu_wait_io_event_common(CPUState *cpu)
{
qatomic_mb_set(&cpu->thread_kicked, false);
if (cpu->stop) {
qemu_cpu_stop(cpu, false);
}
process_queued_cpu_work(cpu);
}
void qemu_wait_io_event(CPUState *cpu)
{
bool slept = false;
while (cpu_thread_is_idle(cpu)) {
if (!slept) {
slept = true;
qemu_plugin_vcpu_idle_cb(cpu);
}
qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex);
}
if (slept) {
qemu_plugin_vcpu_resume_cb(cpu);
}
#ifdef _WIN32
/* Eat dummy APC queued by cpus_kick_thread. */
if (hax_enabled()) {
SleepEx(0, TRUE);
}
#endif
qemu_wait_io_event_common(cpu);
}
void cpus_kick_thread(CPUState *cpu)
{
#ifndef _WIN32
int err;
if (cpu->thread_kicked) {
return;
}
cpu->thread_kicked = true;
err = pthread_kill(cpu->thread->thread, SIG_IPI);
if (err && err != ESRCH) {
fprintf(stderr, "qemu:%s: %s", __func__, strerror(err));
exit(1);
}
#endif
}
void qemu_cpu_kick(CPUState *cpu)
{
qemu_cond_broadcast(cpu->halt_cond);
if (cpus_accel->kick_vcpu_thread) {
cpus_accel->kick_vcpu_thread(cpu);
} else { /* default */
cpus_kick_thread(cpu);
}
}
void qemu_cpu_kick_self(void)
{
assert(current_cpu);
cpus_kick_thread(current_cpu);
}
bool qemu_cpu_is_self(CPUState *cpu)
{
return qemu_thread_is_self(cpu->thread);
}
bool qemu_in_vcpu_thread(void)
{
return current_cpu && qemu_cpu_is_self(current_cpu);
}
static __thread bool iothread_locked = false;
bool qemu_mutex_iothread_locked(void)
{
return iothread_locked;
}
/*
* The BQL is taken from so many places that it is worth profiling the
* callers directly, instead of funneling them all through a single function.
*/
void qemu_mutex_lock_iothread_impl(const char *file, int line)
{
QemuMutexLockFunc bql_lock = qatomic_read(&qemu_bql_mutex_lock_func);
g_assert(!qemu_mutex_iothread_locked());
bql_lock(&qemu_global_mutex, file, line);
iothread_locked = true;
}
void qemu_mutex_unlock_iothread(void)
{
g_assert(qemu_mutex_iothread_locked());
iothread_locked = false;
qemu_mutex_unlock(&qemu_global_mutex);
}
void qemu_cond_wait_iothread(QemuCond *cond)
{
qemu_cond_wait(cond, &qemu_global_mutex);
}
void qemu_cond_timedwait_iothread(QemuCond *cond, int ms)
{
qemu_cond_timedwait(cond, &qemu_global_mutex, ms);
}
/* signal CPU creation */
void cpu_thread_signal_created(CPUState *cpu)
{
cpu->created = true;
qemu_cond_signal(&qemu_cpu_cond);
}
/* signal CPU destruction */
void cpu_thread_signal_destroyed(CPUState *cpu)
{
cpu->created = false;
qemu_cond_signal(&qemu_cpu_cond);
}
static bool all_vcpus_paused(void)
{
CPUState *cpu;
CPU_FOREACH(cpu) {
if (!cpu->stopped) {
return false;
}
}
return true;
}
void pause_all_vcpus(void)
{
CPUState *cpu;
qemu_clock_enable(QEMU_CLOCK_VIRTUAL, false);
CPU_FOREACH(cpu) {
if (qemu_cpu_is_self(cpu)) {
qemu_cpu_stop(cpu, true);
} else {
cpu->stop = true;
qemu_cpu_kick(cpu);
}
}
/* We need to drop the replay_lock so any vCPU threads woken up
* can finish their replay tasks
*/
replay_mutex_unlock();
while (!all_vcpus_paused()) {
qemu_cond_wait(&qemu_pause_cond, &qemu_global_mutex);
CPU_FOREACH(cpu) {
qemu_cpu_kick(cpu);
}
}
qemu_mutex_unlock_iothread();
replay_mutex_lock();
qemu_mutex_lock_iothread();
}
void cpu_resume(CPUState *cpu)
{
cpu->stop = false;
cpu->stopped = false;
qemu_cpu_kick(cpu);
}
void resume_all_vcpus(void)
{
CPUState *cpu;
if (!runstate_is_running()) {
return;
}
qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
CPU_FOREACH(cpu) {
cpu_resume(cpu);
}
}
void cpu_remove_sync(CPUState *cpu)
{
cpu->stop = true;
cpu->unplug = true;
qemu_cpu_kick(cpu);
qemu_mutex_unlock_iothread();
qemu_thread_join(cpu->thread);
qemu_mutex_lock_iothread();
}
void cpus_register_accel(const AccelOpsClass *ops)
{
assert(ops != NULL);
assert(ops->create_vcpu_thread != NULL); /* mandatory */
cpus_accel = ops;
}
void qemu_init_vcpu(CPUState *cpu)
{
MachineState *ms = MACHINE(qdev_get_machine());
cpu->nr_cores = ms->smp.cores;
cpu->nr_threads = ms->smp.threads;
cpu->stopped = true;
cpu->random_seed = qemu_guest_random_seed_thread_part1();
if (!cpu->as) {
/* If the target cpu hasn't set up any address spaces itself,
* give it the default one.
*/
cpu->num_ases = 1;
cpu_address_space_init(cpu, 0, "cpu-memory", cpu->memory);
}
/* accelerators all implement the AccelOpsClass */
g_assert(cpus_accel != NULL && cpus_accel->create_vcpu_thread != NULL);
cpus_accel->create_vcpu_thread(cpu);
while (!cpu->created) {
qemu_cond_wait(&qemu_cpu_cond, &qemu_global_mutex);
}
}
void cpu_stop_current(void)
{
if (current_cpu) {
current_cpu->stop = true;
cpu_exit(current_cpu);
}
}
int vm_stop(RunState state)
{
if (qemu_in_vcpu_thread()) {
qemu_system_vmstop_request_prepare();
qemu_system_vmstop_request(state);
/*
* FIXME: should not return to device code in case
* vm_stop() has been requested.
*/
cpu_stop_current();
return 0;
}
return do_vm_stop(state, true);
}
/**
* Prepare for (re)starting the VM.
* Returns -1 if the vCPUs are not to be restarted (e.g. if they are already
* running or in case of an error condition), 0 otherwise.
*/
int vm_prepare_start(void)
{
RunState requested;
qemu_vmstop_requested(&requested);
if (runstate_is_running() && requested == RUN_STATE__MAX) {
return -1;
}
/* Ensure that a STOP/RESUME pair of events is emitted if a
* vmstop request was pending. The BLOCK_IO_ERROR event, for
* example, according to documentation is always followed by
* the STOP event.
*/
if (runstate_is_running()) {
qapi_event_send_stop();
qapi_event_send_resume();
return -1;
}
/* We are sending this now, but the CPUs will be resumed shortly later */
qapi_event_send_resume();
cpu_enable_ticks();
runstate_set(RUN_STATE_RUNNING);
vm_state_notify(1, RUN_STATE_RUNNING);
return 0;
}
void vm_start(void)
{
if (!vm_prepare_start()) {
resume_all_vcpus();
}
}
/* does a state transition even if the VM is already stopped,
current state is forgotten forever */
int vm_stop_force_state(RunState state)
{
if (runstate_is_running()) {
return vm_stop(state);
} else {
int ret;
runstate_set(state);
bdrv_drain_all();
/* Make sure to return an error if the flush in a previous vm_stop()
* failed. */
ret = bdrv_flush_all();
trace_vm_stop_flush_all(ret);
return ret;
}
}
void list_cpus(const char *optarg)
{
/* XXX: implement xxx_cpu_list for targets that still miss it */
#if defined(cpu_list)
cpu_list();
#endif
}
void qmp_memsave(int64_t addr, int64_t size, const char *filename,
bool has_cpu, int64_t cpu_index, Error **errp)
{
FILE *f;
uint32_t l;
CPUState *cpu;
uint8_t buf[1024];
int64_t orig_addr = addr, orig_size = size;
if (!has_cpu) {
cpu_index = 0;
}
cpu = qemu_get_cpu(cpu_index);
if (cpu == NULL) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cpu-index",
"a CPU number");
return;
}
f = fopen(filename, "wb");
if (!f) {
error_setg_file_open(errp, errno, filename);
return;
}
while (size != 0) {
l = sizeof(buf);
if (l > size)
l = size;
if (cpu_memory_rw_debug(cpu, addr, buf, l, 0) != 0) {
error_setg(errp, "Invalid addr 0x%016" PRIx64 "/size %" PRId64
" specified", orig_addr, orig_size);
goto exit;
}
if (fwrite(buf, 1, l, f) != l) {
error_setg(errp, QERR_IO_ERROR);
goto exit;
}
addr += l;
size -= l;
}
exit:
fclose(f);
}
void qmp_pmemsave(int64_t addr, int64_t size, const char *filename,
Error **errp)
{
FILE *f;
uint32_t l;
uint8_t buf[1024];
f = fopen(filename, "wb");
if (!f) {
error_setg_file_open(errp, errno, filename);
return;
}
while (size != 0) {
l = sizeof(buf);
if (l > size)
l = size;
cpu_physical_memory_read(addr, buf, l);
if (fwrite(buf, 1, l, f) != l) {
error_setg(errp, QERR_IO_ERROR);
goto exit;
}
addr += l;
size -= l;
}
exit:
fclose(f);
}
void qmp_inject_nmi(Error **errp)
{
nmi_monitor_handle(monitor_get_cpu_index(monitor_cur()), errp);
}