[Qemu-devel] [PULL 6/8] virtio-serial: report frontend connection state via monitor

[Luiz Capitulino <lcapitulino@redhat.com>]

From: Laszlo Ersek <lersek@redhat.com>

Libvirt wants to know about the guest-side connection state of some
virtio-serial ports (in particular the one(s) assigned to guest agent(s)).
Report such states with a new monitor event.

RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1080376
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 hw/char/virtio-console.c | 12 +++++++++---
 monitor.c                |  1 +
 qapi/event.json          | 14 ++++++++++++++
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/hw/char/virtio-console.c b/hw/char/virtio-console.c
index 6c8be0f..54eb15f 100644
--- a/hw/char/virtio-console.c
+++ b/hw/char/virtio-console.c
@@ -14,6 +14,7 @@
 #include "qemu/error-report.h"
 #include "trace.h"
 #include "hw/virtio/virtio-serial.h"
+#include "qapi-event.h"
 
 #define TYPE_VIRTIO_CONSOLE_SERIAL_PORT "virtserialport"
 #define VIRTIO_CONSOLE(obj) \
@@ -81,11 +82,16 @@ static ssize_t flush_buf(VirtIOSerialPort *port,
 static void set_guest_connected(VirtIOSerialPort *port, int guest_connected)
 {
     VirtConsole *vcon = VIRTIO_CONSOLE(port);
+    DeviceState *dev = DEVICE(port);
 
-    if (!vcon->chr) {
-        return;
+    if (vcon->chr) {
+        qemu_chr_fe_set_open(vcon->chr, guest_connected);
+    }
+
+    if (dev->id) {
+        qapi_event_send_vserport_change(dev->id, guest_connected,
+                                        &error_abort);
     }
-    qemu_chr_fe_set_open(vcon->chr, guest_connected);
 }
 
 /* Readiness of the guest to accept data on a port */
diff --git a/monitor.c b/monitor.c
index fd34ab7..5718d0b 100644
--- a/monitor.c
+++ b/monitor.c
@@ -588,6 +588,7 @@ static void monitor_qapi_event_init(void)
     monitor_qapi_event_throttle(QAPI_EVENT_BALLOON_CHANGE, 1000);
     monitor_qapi_event_throttle(QAPI_EVENT_QUORUM_REPORT_BAD, 1000);
     monitor_qapi_event_throttle(QAPI_EVENT_QUORUM_FAILURE, 1000);
+    monitor_qapi_event_throttle(QAPI_EVENT_VSERPORT_CHANGE, 1000);
 
     qmp_event_set_func_emit(monitor_qapi_event_queue);
 }
diff --git a/qapi/event.json b/qapi/event.json
index 8f817b1..ff97aeb 100644
--- a/qapi/event.json
+++ b/qapi/event.json
@@ -316,3 +316,17 @@
 { 'event': 'QUORUM_REPORT_BAD',
   'data': { '*error': 'str', 'node-name': 'str',
             'sector-num': 'int', 'sector-count': 'int' } }
+
+##
+# @VSERPORT_CHANGE
+#
+# Emitted when the guest opens or closes a virtio-serial port.
+#
+# @id: device identifier of the virtio-serial port
+#
+# @open: true if the guest has opened the virtio-serial port
+#
+# Since: 2.1
+##
+{ 'event': 'VSERPORT_CHANGE',
+  'data': { 'id': 'str', 'open': 'bool' } }
-- 
1.9.3