Stop current VCPU on synchronous reset requests

If some I/O operation ends up calling qemu_system_reset_request in VCPU
context, we record this and inform the io-thread, but we do not
terminate the VCPU loop. This can lead to fairly unexpected behavior if
the triggering reset operation is supposed to work synchronously.

Fix this for TCG (when run in deterministic I/O mode) by setting the
VCPU on stop and issuing a cpu_exit. KVM requires some more work on its
VCPU loop.

[ ported from qemu-kvm ]

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

diff --git a/cpus.c b/cpus.c
index ab6e40e93d5c886db295601546ac532462e6a45d..f8a88e3bb4b237120112dd5e16c88c7832b0cf12 100644 (file)
--- a/cpus.c
+++ b/cpus.c
@@ -312,6 +312,10 @@ void qemu_notify_event(void)
 void qemu_mutex_lock_iothread(void) {}
 void qemu_mutex_unlock_iothread(void) {}
 
+void cpu_stop_current(void)
+{
+}
+
 void vm_stop(int reason)
 {
     do_vm_stop(reason);
@@ -852,6 +856,14 @@ static void qemu_system_vmstop_request(int reason)
     qemu_notify_event();
 }
 
+void cpu_stop_current(void)
+{
+    if (cpu_single_env) {
+        cpu_single_env->stopped = 1;
+        cpu_exit(cpu_single_env);
+    }
+}
+
 void vm_stop(int reason)
 {
     QemuThread me;
@@ -863,10 +875,7 @@ void vm_stop(int reason)
          * FIXME: should not return to device code in case
          * vm_stop() has been requested.
          */
-        if (cpu_single_env) {
-            cpu_exit(cpu_single_env);
-            cpu_single_env->stop = 1;
-        }
+        cpu_stop_current();
         return;
     }
     do_vm_stop(reason);

diff --git a/cpus.h b/cpus.h
index bf4d9bb87a75f521aed366a50d6257708aeab702..4cadb641c0c27f3dc2b6c6374485788b90e29810 100644 (file)
--- a/cpus.h
+++ b/cpus.h
@@ -6,6 +6,7 @@ int qemu_init_main_loop(void);
 void qemu_main_loop_start(void);
 void resume_all_vcpus(void);
 void pause_all_vcpus(void);
+void cpu_stop_current(void);
 
 /* vl.c */
 extern int smp_cores;

diff --git a/vl.c b/vl.c
index ed2cdfae421815d5fd238113a8d9143e1bd409f9..5e3f7f24e9b8aa0771d117fb59610c3c15691803 100644 (file)
--- a/vl.c
+++ b/vl.c
@@ -1296,6 +1296,7 @@ void qemu_system_reset_request(void)
     } else {
         reset_requested = 1;
     }
+    cpu_stop_current();
     qemu_notify_event();
 }