move vm_start to cpus.c

This patch:

* moves vm_start to cpus.c.
* exports qemu_vmstop_requested, since it's needed by vm_start.
* extracts vm_prepare_start from vm_start; it does what vm_start did,
  except restarting the cpus.
* vm_start now calls vm_prepare_start and then restarts the cpus.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Message-Id: <1487092068-16562-2-git-send-email-imbrenda@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/cpus.c b/cpus.c
index 71a82e5004..0bcb5b50b6 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1578,6 +1578,48 @@ int vm_stop(RunState state)
     return do_vm_stop(state);
 }
 
+/**
+ * Prepare for (re)starting the VM.
+ * Returns -1 if the vCPUs are not to be restarted (e.g. if they are already
+ * running or in case of an error condition), 0 otherwise.
+ */
+int vm_prepare_start(void)
+{
+    RunState requested;
+    int res = 0;
+
+    qemu_vmstop_requested(&requested);
+    if (runstate_is_running() && requested == RUN_STATE__MAX) {
+        return -1;
+    }
+
+    /* Ensure that a STOP/RESUME pair of events is emitted if a
+     * vmstop request was pending.  The BLOCK_IO_ERROR event, for
+     * example, according to documentation is always followed by
+     * the STOP event.
+     */
+    if (runstate_is_running()) {
+        qapi_event_send_stop(&error_abort);
+        res = -1;
+    } else {
+        replay_enable_events();
+        cpu_enable_ticks();
+        runstate_set(RUN_STATE_RUNNING);
+        vm_state_notify(1, RUN_STATE_RUNNING);
+    }
+
+    /* We are sending this now, but the CPUs will be resumed shortly later */
+    qapi_event_send_resume(&error_abort);
+    return res;
+}
+
+void vm_start(void)
+{
+    if (!vm_prepare_start()) {
+        resume_all_vcpus();
+    }
+}
+
 /* does a state transition even if the VM is already stopped,
    current state is forgotten forever */
 int vm_stop_force_state(RunState state)