accel/qtest: Support qtest accelerator for Windows

Currently signal SIGIPI [=SIGUSR1] is used to kick the dummy CPU
when qtest accelerator is used. However SIGUSR1 is unsupported on
Windows. To support Windows, we add a QemuSemaphore CPUState::sem
to kick the dummy CPU instead for Windows.

Signed-off-by: Xuzhou Cheng <xuzhou.cheng@windriver.com>
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20221028045736.679903-2-bin.meng@windriver.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

accel/dummy-cpus.c

@@ -21,8 +21,6 @@
 static void *dummy_cpu_thread_fn(void *arg)
 {
     CPUState *cpu = arg;
-    sigset_t waitset;
-    int r;
 
     rcu_register_thread();
 
@@ -32,8 +30,13 @@ static void *dummy_cpu_thread_fn(void *arg)
     cpu->can_do_io = 1;
     current_cpu = cpu;
 
+#ifndef _WIN32
+    sigset_t waitset;
+    int r;
+
     sigemptyset(&waitset);
     sigaddset(&waitset, SIG_IPI);
+#endif
 
     /* signal CPU creation */
     cpu_thread_signal_created(cpu);
@@ -41,6 +44,7 @@ static void *dummy_cpu_thread_fn(void *arg)
 
     do {
         qemu_mutex_unlock_iothread();
+#ifndef _WIN32
         do {
             int sig;
             r = sigwait(&waitset, &sig);
@@ -49,6 +53,9 @@ static void *dummy_cpu_thread_fn(void *arg)
             perror("sigwait");
             exit(1);
         }
+#else
+        qemu_sem_wait(&cpu->sem);
+#endif
         qemu_mutex_lock_iothread();
         qemu_wait_io_event(cpu);
     } while (!cpu->unplug);
@@ -69,4 +76,7 @@ void dummy_start_vcpu_thread(CPUState *cpu)
              cpu->cpu_index);
     qemu_thread_create(cpu->thread, thread_name, dummy_cpu_thread_fn, cpu,
                        QEMU_THREAD_JOINABLE);
+#ifdef _WIN32
+    qemu_sem_init(&cpu->sem, 0);
+#endif
 }

accel/meson.build

@@ -16,5 +16,5 @@ dummy_ss.add(files(
   'dummy-cpus.c',
 ))
 
-specific_ss.add_all(when: ['CONFIG_SOFTMMU', 'CONFIG_POSIX'], if_true: dummy_ss)
+specific_ss.add_all(when: ['CONFIG_SOFTMMU'], if_true: dummy_ss)
 specific_ss.add_all(when: ['CONFIG_XEN'], if_true: dummy_ss)

accel/qtest/meson.build

@@ -1,2 +1 @@
-qtest_module_ss.add(when: ['CONFIG_SOFTMMU', 'CONFIG_POSIX'],
+qtest_module_ss.add(when: ['CONFIG_SOFTMMU'], if_true: files('qtest.c'))
-                    if_true: files('qtest.c'))

include/hw/core/cpu.h

@@ -333,6 +333,7 @@ struct CPUState {
     struct QemuThread *thread;
 #ifdef _WIN32
     HANDLE hThread;
+    QemuSemaphore sem;
 #endif
     int thread_id;
     bool running, has_waiter;

softmmu/cpus.c

@@ -437,18 +437,19 @@ void qemu_wait_io_event(CPUState *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);
+
+#ifndef _WIN32
+    int err = pthread_kill(cpu->thread->thread, SIG_IPI);
     if (err && err != ESRCH) {
         fprintf(stderr, "qemu:%s: %s", __func__, strerror(err));
         exit(1);
     }
+#else
+    qemu_sem_post(&cpu->sem);
 #endif
 }