qemu: Add handling for VSERPORT_CHANGE event

New qemu added a new event that is emitted when a virtio serial channel
is opened in the guest OS. This allows us to update the state of the
port in the output-only XML element.

This patch implements the monitor callbacks and necessary handlers to
update the state in the definition.

src/qemu/qemu_domain.h

@@ -196,6 +196,7 @@ typedef enum {
     QEMU_PROCESS_EVENT_GUESTPANIC,
     QEMU_PROCESS_EVENT_DEVICE_DELETED,
     QEMU_PROCESS_EVENT_NIC_RX_FILTER_CHANGED,
+    QEMU_PROCESS_EVENT_SERIAL_CHANGED,
 
     QEMU_PROCESS_EVENT_LAST
 } qemuProcessEventType;

src/qemu/qemu_driver.c

@@ -4334,6 +4334,60 @@ processNicRxFilterChangedEvent(virQEMUDriverPtr driver,
 }
 
 
+static void
+processSerialChangedEvent(virQEMUDriverPtr driver,
+                          virDomainObjPtr vm,
+                          char *devAlias,
+                          bool connected)
+{
+    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+    virDomainChrDeviceState newstate;
+    virDomainDeviceDef dev;
+
+    if (connected)
+        newstate = VIR_DOMAIN_CHR_DEVICE_STATE_CONNECTED;
+    else
+        newstate = VIR_DOMAIN_CHR_DEVICE_STATE_DISCONNECTED;
+
+    VIR_DEBUG("Changing serial port state %s in domain %p %s",
+              devAlias, vm, vm->def->name);
+
+    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
+        goto cleanup;
+
+    if (!virDomainObjIsActive(vm)) {
+        VIR_DEBUG("Domain is not running");
+        goto endjob;
+    }
+
+    if (virDomainDefFindDevice(vm->def, devAlias, &dev, true) < 0)
+        goto endjob;
+
+    /* we care only about certain devices */
+    if (dev.type != VIR_DOMAIN_DEVICE_CHR ||
+        dev.data.chr->deviceType != VIR_DOMAIN_CHR_DEVICE_TYPE_CHANNEL ||
+        dev.data.chr->targetType != VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_VIRTIO)
+        goto endjob;
+
+    dev.data.chr->state = newstate;
+
+    if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0)
+        VIR_WARN("unable to save status of domain %s after updating state of "
+                 "channel %s", vm->def->name, devAlias);
+
+ endjob:
+    /* We had an extra reference to vm before starting a new job so ending the
+     * job is guaranteed not to remove the last reference.
+     */
+    ignore_value(qemuDomainObjEndJob(driver, vm));
+
+ cleanup:
+    VIR_FREE(devAlias);
+    virObjectUnref(cfg);
+
+}
+
+
 static void qemuProcessEventHandler(void *data, void *opaque)
 {
     struct qemuProcessEvent *processEvent = data;
@@ -4357,6 +4411,9 @@ static void qemuProcessEventHandler(void *data, void *opaque)
     case QEMU_PROCESS_EVENT_NIC_RX_FILTER_CHANGED:
         processNicRxFilterChangedEvent(driver, vm, processEvent->data);
         break;
+    case QEMU_PROCESS_EVENT_SERIAL_CHANGED:
+        processSerialChangedEvent(driver, vm, processEvent->data,
+                                  processEvent->action);
     case QEMU_PROCESS_EVENT_LAST:
         break;
     }

src/qemu/qemu_monitor.c

@@ -1400,6 +1400,20 @@ qemuMonitorEmitNicRxFilterChanged(qemuMonitorPtr mon,
 }
 
 
+int
+qemuMonitorEmitSerialChange(qemuMonitorPtr mon,
+                            const char *devAlias,
+                            bool connected)
+{
+    int ret = -1;
+    VIR_DEBUG("mon=%p, devAlias='%s', connected=%d", mon, devAlias, connected);
+
+    QEMU_MONITOR_CALLBACK(mon, ret, domainSerialChange, mon->vm, devAlias, connected);
+
+    return ret;
+}
+
+
 int qemuMonitorSetCapabilities(qemuMonitorPtr mon)
 {
     int ret;

src/qemu/qemu_monitor.h

@@ -176,6 +176,12 @@ typedef int (*qemuMonitorDomainNicRxFilterChangedCallback)(qemuMonitorPtr mon,
                                                            const char *devAlias,
                                                            void *opaque);
 
+typedef int (*qemuMonitorDomainSerialChangeCallback)(qemuMonitorPtr mon,
+                                                     virDomainObjPtr vm,
+                                                     const char *devAlias,
+                                                     bool connected,
+                                                     void *opaque);
+
 typedef struct _qemuMonitorCallbacks qemuMonitorCallbacks;
 typedef qemuMonitorCallbacks *qemuMonitorCallbacksPtr;
 struct _qemuMonitorCallbacks {
@@ -202,6 +208,7 @@ struct _qemuMonitorCallbacks {
     qemuMonitorDomainGuestPanicCallback domainGuestPanic;
     qemuMonitorDomainDeviceDeletedCallback domainDeviceDeleted;
     qemuMonitorDomainNicRxFilterChangedCallback domainNicRxFilterChanged;
+    qemuMonitorDomainSerialChangeCallback domainSerialChange;
 };
 
 char *qemuMonitorEscapeArg(const char *in);
@@ -292,6 +299,9 @@ int qemuMonitorEmitDeviceDeleted(qemuMonitorPtr mon,
                                  const char *devAlias);
 int qemuMonitorEmitNicRxFilterChanged(qemuMonitorPtr mon,
                                       const char *devAlias);
+int qemuMonitorEmitSerialChange(qemuMonitorPtr mon,
+                                const char *devAlias,
+                                bool connected);
 
 int qemuMonitorStartCPUs(qemuMonitorPtr mon,
                          virConnectPtr conn);

src/qemu/qemu_monitor_json.c

@@ -82,6 +82,7 @@ static void qemuMonitorJSONHandlePMSuspendDisk(qemuMonitorPtr mon, virJSONValueP
 static void qemuMonitorJSONHandleGuestPanic(qemuMonitorPtr mon, virJSONValuePtr data);
 static void qemuMonitorJSONHandleDeviceDeleted(qemuMonitorPtr mon, virJSONValuePtr data);
 static void qemuMonitorJSONHandleNicRxFilterChanged(qemuMonitorPtr mon, virJSONValuePtr data);
+static void qemuMonitorJSONHandleSerialChange(qemuMonitorPtr mon, virJSONValuePtr data);
 
 typedef struct {
     const char *type;
@@ -112,6 +113,7 @@ static qemuEventHandler eventHandlers[] = {
     { "VNC_CONNECTED", qemuMonitorJSONHandleVNCConnect, },
     { "VNC_DISCONNECTED", qemuMonitorJSONHandleVNCDisconnect, },
     { "VNC_INITIALIZED", qemuMonitorJSONHandleVNCInitialize, },
+    { "VSERPORT_CHANGE", qemuMonitorJSONHandleSerialChange, },
     { "WAKEUP", qemuMonitorJSONHandlePMWakeup, },
     { "WATCHDOG", qemuMonitorJSONHandleWatchdog, },
     /* We use bsearch, so keep this list sorted.  */
@@ -895,6 +897,27 @@ qemuMonitorJSONHandleNicRxFilterChanged(qemuMonitorPtr mon, virJSONValuePtr data
 }
 
 
+static void
+qemuMonitorJSONHandleSerialChange(qemuMonitorPtr mon,
+                                  virJSONValuePtr data)
+{
+    const char *name;
+    bool connected;
+
+    if (!(name = virJSONValueObjectGetString(data, "id"))) {
+        VIR_WARN("missing device alias in VSERPORT_CHANGE event");
+        return;
+    }
+
+    if (virJSONValueObjectGetBoolean(data, "open", &connected) < 0) {
+        VIR_WARN("missing port state for '%s' in VSERPORT_CHANGE event", name);
+        return;
+    }
+
+    qemuMonitorEmitSerialChange(mon, name, connected);
+}
+
+
 int
 qemuMonitorJSONHumanCommandWithFd(qemuMonitorPtr mon,
                                   const char *cmd_str,

src/qemu/qemu_process.c

@@ -1540,6 +1540,49 @@ qemuProcessHandleNicRxFilterChanged(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
 }
 
 
+static int
+qemuProcessHandleSerialChanged(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
+                               virDomainObjPtr vm,
+                               const char *devAlias,
+                               bool connected,
+                               void *opaque)
+{
+    virQEMUDriverPtr driver = opaque;
+    struct qemuProcessEvent *processEvent = NULL;
+    char *data;
+
+    virObjectLock(vm);
+
+    VIR_DEBUG("Serial port %s state changed to '%d' in domain %p %s",
+              devAlias, connected, vm, vm->def->name);
+
+    if (VIR_ALLOC(processEvent) < 0)
+        goto error;
+
+    processEvent->eventType = QEMU_PROCESS_EVENT_SERIAL_CHANGED;
+    if (VIR_STRDUP(data, devAlias) < 0)
+        goto error;
+    processEvent->data = data;
+    processEvent->action = connected;
+    processEvent->vm = vm;
+
+    virObjectRef(vm);
+    if (virThreadPoolSendJob(driver->workerPool, 0, processEvent) < 0) {
+        ignore_value(virObjectUnref(vm));
+        goto error;
+    }
+
+ cleanup:
+    virObjectUnlock(vm);
+    return 0;
+ error:
+    if (processEvent)
+        VIR_FREE(processEvent->data);
+    VIR_FREE(processEvent);
+    goto cleanup;
+}
+
+
 static qemuMonitorCallbacks monitorCallbacks = {
     .eofNotify = qemuProcessHandleMonitorEOF,
     .errorNotify = qemuProcessHandleMonitorError,
@@ -1562,6 +1605,7 @@ static qemuMonitorCallbacks monitorCallbacks = {
     .domainGuestPanic = qemuProcessHandleGuestPanic,
     .domainDeviceDeleted = qemuProcessHandleDeviceDeleted,
     .domainNicRxFilterChanged = qemuProcessHandleNicRxFilterChanged,
+    .domainSerialChange = qemuProcessHandleSerialChanged,
 };
 
 static int