Flatten the main loop

First of all, vm_can_run is a misnomer, it actually means "no request
pending". Moreover, there is no need to check all pending requests
twice, the first time via the inner loop check and then again when
actually processing the requests. We can simply remove the inner loop
and do the checks directly.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

vl.c

@@ -1389,14 +1389,16 @@ void main_loop_wait(int nonblocking)
 
 }
 
-static int vm_can_run(void)
+#ifndef CONFIG_IOTHREAD
+static int vm_request_pending(void)
 {
-    return !(powerdown_requested ||
+    return powerdown_requested ||
            reset_requested ||
            shutdown_requested ||
            debug_requested ||
-             vmstop_requested);
+           vmstop_requested;
 }
+#endif
 
 qemu_irq qemu_system_powerdown;
 
@@ -1411,10 +1413,9 @@ static void main_loop(void)
     qemu_main_loop_start();
 
     for (;;) {
-        do {
 #ifndef CONFIG_IOTHREAD
         nonblocking = cpu_exec_all();
-            if (!vm_can_run()) {
+        if (vm_request_pending()) {
             nonblocking = true;
         }
 #endif
@@ -1425,7 +1426,6 @@ static void main_loop(void)
 #ifdef CONFIG_PROFILER
         dev_time += profile_getclock() - ti;
 #endif
-        } while (vm_can_run());
 
         if ((r = qemu_debug_requested())) {
             vm_stop(r);