virtio-console: Add some trace events

Add some trace events for messages passed between the char layer and the
virtio-serial bus.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index b076331..713a761 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -12,6 +12,7 @@
 
 #include "qemu-char.h"
 #include "qemu-error.h"
+#include "trace.h"
 #include "virtio-serial.h"
 
 typedef struct VirtConsole {
@@ -24,8 +25,12 @@
 static ssize_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len)
 {
     VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port);
+    ssize_t ret;
 
-    return qemu_chr_write(vcon->chr, buf, len);
+    ret = qemu_chr_write(vcon->chr, buf, len);
+
+    trace_virtio_console_flush_buf(port->id, len, ret);
+    return ret;
 }
 
 /* Callback function that's called when the guest opens the port */
@@ -57,6 +62,7 @@
 {
     VirtConsole *vcon = opaque;
 
+    trace_virtio_console_chr_read(vcon->port.id, size);
     virtio_serial_write(&vcon->port, buf, size);
 }
 
@@ -64,6 +70,7 @@
 {
     VirtConsole *vcon = opaque;
 
+    trace_virtio_console_chr_event(vcon->port.id, event);
     switch (event) {
     case CHR_EVENT_OPENED:
         virtio_serial_open(&vcon->port);