Introduce VCPU self-signaling service

Introduce qemu_cpu_kick_self to send SIG_IPI to the calling VCPU
context. First user will be kvm.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

cpus.c

@@ -529,6 +529,17 @@ void qemu_cpu_kick(void *env)
     return;
 }
 
+void qemu_cpu_kick_self(void)
+{
+#ifndef _WIN32
+    assert(cpu_single_env);
+
+    raise(SIG_IPI);
+#else
+    abort();
+#endif
+}
+
 void qemu_notify_event(void)
 {
     CPUState *env = cpu_single_env;
@@ -831,6 +842,16 @@ void qemu_cpu_kick(void *_env)
     }
 }
 
+void qemu_cpu_kick_self(void)
+{
+    assert(cpu_single_env);
+
+    if (!cpu_single_env->thread_kicked) {
+        qemu_thread_signal(cpu_single_env->thread, SIG_IPI);
+        cpu_single_env->thread_kicked = true;
+    }
+}
+
 int qemu_cpu_self(void *_env)
 {
     CPUState *env = _env;

qemu-common.h

@@ -288,6 +288,7 @@ void qemu_notify_event(void);
 
 /* Unblock cpu */
 void qemu_cpu_kick(void *env);
+void qemu_cpu_kick_self(void);
 int qemu_cpu_self(void *env);
 
 /* work queue */