Move debug exception handling out of cpu_exec

To prepare splitting up KVM and TCG CPU entry/exit, move the debug
exception into cpus.c and invoke cpu_handle_debug_exception on return
from qemu_cpu_exec.

This also allows to clean up the debug request signaling: We can assign
the job of informing main-loop to qemu_system_debug_request and stop the
calling cpu directly in cpu_handle_debug_exception. That means a debug
stop will now only be signaled via debug_requested and not additionally
via vmstop_requested.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

cpu-exec.c

@@ -196,28 +196,6 @@ static inline TranslationBlock *tb_find_fast(void)
     return tb;
 }
 
-static CPUDebugExcpHandler *debug_excp_handler;
-
-CPUDebugExcpHandler *cpu_set_debug_excp_handler(CPUDebugExcpHandler *handler)
-{
-    CPUDebugExcpHandler *old_handler = debug_excp_handler;
-
-    debug_excp_handler = handler;
-    return old_handler;
-}
-
-static void cpu_handle_debug_exception(CPUState *env)
-{
-    CPUWatchpoint *wp;
-
-    if (!env->watchpoint_hit)
-        QTAILQ_FOREACH(wp, &env->watchpoints, entry)
-            wp->flags &= ~BP_WATCHPOINT_HIT;
-
-    if (debug_excp_handler)
-        debug_excp_handler(env);
-}
-
 /* main execution loop */
 
 volatile sig_atomic_t exit_request;
@@ -287,8 +265,6 @@ int cpu_exec(CPUState *env1)
                 if (env->exception_index >= EXCP_INTERRUPT) {
                     /* exit request from the cpu execution loop */
                     ret = env->exception_index;
-                    if (ret == EXCP_DEBUG)
-                        cpu_handle_debug_exception(env);
                     break;
                 } else {
 #if defined(CONFIG_USER_ONLY)

cpus.c

@@ -165,10 +165,34 @@ static bool all_cpu_threads_idle(void)
     return true;
 }
 
-static void cpu_debug_handler(CPUState *env)
+static CPUDebugExcpHandler *debug_excp_handler;
+
+CPUDebugExcpHandler *cpu_set_debug_excp_handler(CPUDebugExcpHandler *handler)
+{
+    CPUDebugExcpHandler *old_handler = debug_excp_handler;
+
+    debug_excp_handler = handler;
+    return old_handler;
+}
+
+static void cpu_handle_debug_exception(CPUState *env)
 {
+    CPUWatchpoint *wp;
+
+    if (!env->watchpoint_hit) {
+        QTAILQ_FOREACH(wp, &env->watchpoints, entry) {
+            wp->flags &= ~BP_WATCHPOINT_HIT;
+        }
+    }
+    if (debug_excp_handler) {
+        debug_excp_handler(env);
+    }
+
     gdb_set_stop_cpu(env);
     qemu_system_debug_request();
+#ifdef CONFIG_IOTHREAD
+    env->stopped = 1;
+#endif
 }
 
 #ifdef CONFIG_LINUX
@@ -479,7 +503,6 @@ int qemu_init_main_loop(void)
         return ret;
     }
 #endif
-    cpu_set_debug_excp_handler(cpu_debug_handler);
 
     qemu_init_sigbus();
 
@@ -653,8 +676,6 @@ int qemu_init_main_loop(void)
     int ret;
     sigset_t blocked_signals;
 
-    cpu_set_debug_excp_handler(cpu_debug_handler);
-
     qemu_init_sigbus();
 
     blocked_signals = block_io_signals();
@@ -808,7 +829,10 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
 
     while (1) {
         if (cpu_can_run(env)) {
-            qemu_cpu_exec(env);
+            r = qemu_cpu_exec(env);
+            if (r == EXCP_DEBUG) {
+                cpu_handle_debug_exception(env);
+            }
         }
         qemu_kvm_wait_io_event(env);
     }
@@ -1076,6 +1100,7 @@ bool cpu_exec_all(void)
                 qemu_kvm_eat_signals(env);
             }
             if (r == EXCP_DEBUG) {
+                cpu_handle_debug_exception(env);
                 break;
             }
         } else if (env->stop) {

vl.c

@@ -1315,7 +1315,7 @@ void qemu_system_powerdown_request(void)
 void qemu_system_debug_request(void)
 {
     debug_requested = 1;
-    vm_stop(VMSTOP_DEBUG);
+    qemu_notify_event();
 }
 
 void qemu_system_vmstop_request(int reason)