qtest: add test framework

The idea behind qtest is pretty simple.  Instead of executing a CPU via TCG or
KVM, rely on an external process to send events to the device model that the CPU
would normally generate.

qtest presents itself as an accelerator.  In addition, a new option is added to
establish a qtest server (-qtest) that takes a character device.  This is what
allows the external process to send CPU events to the device model.

qtest uses a simple line based protocol to send the events.  Documentation of
that protocol is in qtest.c.

I considered reusing the monitor for this job.  Adding interrupts would be a bit
difficult.  In addition, logging would also be difficult.

qtest has extensive logging support.  All protocol commands are logged with
time stamps using a new command line option (-qtest-log).  Logging is important
since ultimately, this is a feature for debugging.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 59 insertions, 3 deletions

diff --git a/cpus.c b/cpus.c
index 25ba621da5..ab8d67b9d8 100644
--- a/cpus.c
+++ b/cpus.c
@@ -741,6 +741,48 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
     return NULL;
 }
 
+static void *qemu_dummy_cpu_thread_fn(void *arg)
+{
+#ifdef _WIN32
+    fprintf(stderr, "qtest is not supported under Windows\n");
+    exit(1);
+#else
+    CPUArchState *env = arg;
+    sigset_t waitset;
+    int r;
+
+    qemu_mutex_lock_iothread();
+    qemu_thread_get_self(env->thread);
+    env->thread_id = qemu_get_thread_id();
+
+    sigemptyset(&waitset);
+    sigaddset(&waitset, SIG_IPI);
+
+    /* signal CPU creation */
+    env->created = 1;
+    qemu_cond_signal(&qemu_cpu_cond);
+
+    cpu_single_env = env;
+    while (1) {
+        cpu_single_env = NULL;
+        qemu_mutex_unlock_iothread();
+        do {
+            int sig;
+            r = sigwait(&waitset, &sig);
+        } while (r == -1 && (errno == EAGAIN || errno == EINTR));
+        if (r == -1) {
+            perror("sigwait");
+            exit(1);
+        }
+        qemu_mutex_lock_iothread();
+        cpu_single_env = env;
+        qemu_wait_io_event_common(env);
+    }
+
+    return NULL;
+#endif
+}
+
 static void tcg_exec_all(void);
 
 static void *qemu_tcg_cpu_thread_fn(void *arg)
@@ -803,7 +845,7 @@ void qemu_cpu_kick(void *_env)
     CPUArchState *env = _env;
 
     qemu_cond_broadcast(env->halt_cond);
-    if (kvm_enabled() && !env->thread_kicked) {
+    if (!tcg_enabled() && !env->thread_kicked) {
         qemu_cpu_kick_thread(env);
         env->thread_kicked = true;
     }
@@ -832,7 +874,7 @@ int qemu_cpu_is_self(void *_env)
 
 void qemu_mutex_lock_iothread(void)
 {
-    if (kvm_enabled()) {
+    if (!tcg_enabled()) {
         qemu_mutex_lock(&qemu_global_mutex);
     } else {
         iothread_requesting_mutex = true;
@@ -947,6 +989,18 @@ static void qemu_kvm_start_vcpu(CPUArchState *env)
     }
 }
 
+static void qemu_dummy_start_vcpu(CPUArchState *env)
+{
+    env->thread = g_malloc0(sizeof(QemuThread));
+    env->halt_cond = g_malloc0(sizeof(QemuCond));
+    qemu_cond_init(env->halt_cond);
+    qemu_thread_create(env->thread, qemu_dummy_cpu_thread_fn, env,
+                       QEMU_THREAD_JOINABLE);
+    while (env->created == 0) {
+        qemu_cond_wait(&qemu_cpu_cond, &qemu_global_mutex);
+    }
+}
+
 void qemu_init_vcpu(void *_env)
 {
     CPUArchState *env = _env;
@@ -956,8 +1010,10 @@ void qemu_init_vcpu(void *_env)
     env->stopped = 1;
     if (kvm_enabled()) {
         qemu_kvm_start_vcpu(env);
-    } else {
+    } else if (tcg_enabled()) {
         qemu_tcg_init_vcpu(env);
+    } else {
+        qemu_dummy_start_vcpu(env);
     }
 }