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>

1 files changed, 13 insertions, 4 deletions

diff --git a/cpus.c b/cpus.c
index ab6e40e93d..f8a88e3bb4 100644
--- 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);