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[Qemu-devel] [patch 08/10] qemu: pause and resume cpu threads
From: |
Marcelo Tosatti |
Subject: |
[Qemu-devel] [patch 08/10] qemu: pause and resume cpu threads |
Date: |
Wed, 25 Mar 2009 19:47:22 -0300 |
User-agent: |
quilt/0.47-1 |
Since cpu emulation happens on a separate thread, it is necessary to
pause/resume it upon certain events such as reset, debug exception,
live migration, etc.
Signed-off-by: Marcelo Tosatti <address@hidden>
Index: trunk/cpu-defs.h
===================================================================
--- trunk.orig/cpu-defs.h
+++ trunk/cpu-defs.h
@@ -172,6 +172,8 @@ typedef struct CPUWatchpoint {
target_ulong mem_io_vaddr; /* target virtual addr at which the \
memory was accessed */ \
uint32_t halted; /* Nonzero if the CPU is in suspend state */ \
+ uint32_t stop; /* Stop request */ \
+ uint32_t stopped; /* Artificially stopped */ \
uint32_t interrupt_request; \
volatile sig_atomic_t exit_request; \
/* The meaning of the MMU modes is defined in the target code. */ \
Index: trunk/vl.c
===================================================================
--- trunk.orig/vl.c
+++ trunk/vl.c
@@ -292,6 +292,11 @@ QemuCond qemu_cpu_cond;
/* system init */
QemuCond qemu_system_cond;
+QemuCond qemu_pause_cond;
+
+static void pause_all_vcpus(void);
+static void resume_all_vcpus(void);
+
/***********************************************************/
/* x86 ISA bus support */
@@ -3539,6 +3544,7 @@ void vm_start(void)
if (!vm_running) {
cpu_enable_ticks();
vm_running = 1;
+ resume_all_vcpus();
vm_state_notify(1, 0);
qemu_rearm_alarm_timer(alarm_timer);
}
@@ -3549,6 +3555,7 @@ void vm_stop(int reason)
if (vm_running) {
cpu_disable_ticks();
vm_running = 0;
+ pause_all_vcpus();
vm_state_notify(0, reason);
}
}
@@ -3737,8 +3744,29 @@ static void host_main_loop_wait(int *tim
}
#endif
+/* Q: is it allowed to enter cpu_exec */
+static int cpu_can_run(CPUState *env)
+{
+ if (env->stop)
+ return 0;
+ if (env->stopped)
+ return 0;
+ if (shutdown_requested)
+ return 0;
+ if (powerdown_requested)
+ return 0;
+ if (reset_requested)
+ return 0;
+ return 1;
+}
+
+/* Q: should break out of the wait loop */
static int cpu_has_work(CPUState *env)
{
+ if (env->stop)
+ return 1;
+ if (env->stopped)
+ return 0;
if (!env->halted)
return 1;
if (qemu_cpu_has_work(env))
@@ -3771,6 +3799,11 @@ static void qemu_wait_io_event(CPUState
qemu_mutex_unlock(&qemu_fair_mutex);
qemu_mutex_lock(&qemu_global_mutex);
+ if (env->stop) {
+ env->stop = 0;
+ env->stopped = 1;
+ qemu_cond_signal(&qemu_pause_cond);
+ }
}
void qemu_cpu_kick(void *_env)
@@ -3837,6 +3870,53 @@ static void qemu_signal_lock(unsigned in
qemu_mutex_unlock(&qemu_fair_mutex);
}
+static int all_vcpus_paused(void)
+{
+ CPUState *penv = first_cpu;
+
+ while (penv) {
+ if (penv->stop)
+ return 0;
+ penv = (CPUState *)penv->next_cpu;
+ }
+
+ return 1;
+}
+
+static void pause_all_vcpus(void)
+{
+ CPUState *penv = first_cpu;
+
+ while (penv) {
+ penv->stop = 1;
+ qemu_thread_signal(penv->thread, SIGUSR1);
+ qemu_cpu_kick(penv);
+ penv = (CPUState *)penv->next_cpu;
+ }
+
+ while (!all_vcpus_paused()) {
+ qemu_cond_timedwait(&qemu_pause_cond, &qemu_global_mutex, 100);
+ penv = first_cpu;
+ while (penv) {
+ qemu_thread_signal(penv->thread, SIGUSR1);
+ penv = (CPUState *)penv->next_cpu;
+ }
+ }
+}
+
+static void resume_all_vcpus(void)
+{
+ CPUState *penv = first_cpu;
+
+ while (penv) {
+ penv->stop = 0;
+ penv->stopped = 0;
+ qemu_thread_signal(penv->thread, SIGUSR1);
+ qemu_cpu_kick(penv);
+ penv = (CPUState *)penv->next_cpu;
+ }
+}
+
void main_loop_wait(int timeout)
{
IOHandlerRecord *ioh;
@@ -3999,7 +4079,9 @@ static void *cpu_main_loop(void *arg)
env->icount_decr.u16.low = decr;
env->icount_extra = count;
}
- ret = cpu_exec(env);
+ ret = EXCP_HALTED;
+ if (cpu_can_run(env))
+ ret = cpu_exec(env);
#ifdef CONFIG_PROFILER
qemu_time += profile_getclock() - ti;
#endif
@@ -4113,6 +4195,7 @@ void qemu_init_vcpu(void *_env)
static void qemu_init_state(void)
{
+ qemu_cond_init(&qemu_pause_cond);
qemu_mutex_init(&qemu_fair_mutex);
qemu_mutex_init(&qemu_global_mutex);
qemu_mutex_lock(&qemu_global_mutex);
@@ -4131,14 +4214,18 @@ static void main_loop(void)
while (1) {
main_loop_wait(1000);
if (qemu_shutdown_requested()) {
+ pause_all_vcpus();
if (no_shutdown)
no_shutdown = 0;
else
break;
} else if (qemu_powerdown_requested())
qemu_system_powerdown();
- else if (qemu_reset_requested())
+ else if (qemu_reset_requested()) {
+ pause_all_vcpus();
qemu_system_reset();
+ resume_all_vcpus();
+ }
}
}
- [Qemu-devel] [patch 04/10] qemu: introduce main_loop_break, (continued)
[Qemu-devel] [patch 05/10] qemu: separate thread for io, Marcelo Tosatti, 2009/03/25
[Qemu-devel] [patch 07/10] qemu: handle reset/poweroff/shutdown in iothread, Marcelo Tosatti, 2009/03/25
[Qemu-devel] [patch 08/10] qemu: pause and resume cpu threads,
Marcelo Tosatti <=
[Qemu-devel] [patch 09/10] qemu: handle vmstop from cpu context, Marcelo Tosatti, 2009/03/25
[Qemu-devel] [patch 10/10] qemu: basic kvm iothread support, Marcelo Tosatti, 2009/03/25
Re: [Qemu-devel] [patch 00/10] iothread (candidate for inclusion), Blue Swirl, 2009/03/29