[Qemu-devel] [PATCH 2/2] virtio-console: Notify resize to the guest.

[Amit Shah <amit.shah@redhat.com>]

From: Kusanagi Kouichi <slash@ac.auone-net.jp>

I tested this patch as follows: I put printf()s into involved
functions. Then ran qemu on a terminal emulator, and resized it. The
guest kernel gets initial size, and follows host resize. Both singleport
and multiport work.

Signed-off-by: Kusanagi Kouichi <slash@ac.auone-net.jp>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/virtio-console.c    |    3 +++
 hw/virtio-serial-bus.c |   15 +++++++++++++++
 hw/virtio-serial.h     |   11 +++++++++--
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index caea11f..58246d1 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -55,6 +55,9 @@ static void chr_event(void *opaque, int event)
     case CHR_EVENT_CLOSED:
         virtio_serial_close(&vcon->port);
         break;
+    case CHR_EVENT_RESIZE:
+        virtio_serial_resize_console(&vcon->port, vcon->chr->rows, vcon->chr->cols);
+        break;
     }
 }
 
diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index 97694d5..8766f1d 100644
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -205,6 +205,20 @@ int virtio_serial_close(VirtIOSerialPort *port)
     return 0;
 }
 
+void virtio_serial_resize_console(VirtIOSerialPort *port, int rows, int cols)
+{
+    VirtIOSerial *vser = port->vser;
+
+    vser->config.rows = rows;
+    vser->config.cols = cols;
+
+    if (use_multiport(vser)) {
+        send_control_event(port, VIRTIO_CONSOLE_RESIZE, 0);
+    } else {
+        virtio_notify_config(&vser->vdev);
+    }
+}
+
 /* Individual ports/apps call this function to write to the guest. */
 ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf,
                             size_t size)
@@ -425,6 +439,7 @@ static uint32_t get_features(VirtIODevice *vdev, uint32_t features)
 
     vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 
+    features |= (1 << VIRTIO_CONSOLE_F_SIZE);
     if (vser->bus->max_nr_ports > 1) {
         features |= (1 << VIRTIO_CONSOLE_F_MULTIPORT);
     }
diff --git a/hw/virtio-serial.h b/hw/virtio-serial.h
index a93b545..f685ee4 100644
--- a/hw/virtio-serial.h
+++ b/hw/virtio-serial.h
@@ -25,14 +25,16 @@
 #define VIRTIO_ID_CONSOLE		3
 
 /* Features supported */
+#define VIRTIO_CONSOLE_F_SIZE		0
 #define VIRTIO_CONSOLE_F_MULTIPORT	1
 
 #define VIRTIO_CONSOLE_BAD_ID           (~(uint32_t)0)
 
 struct virtio_console_config {
     /*
-     * These two fields are used by VIRTIO_CONSOLE_F_SIZE which
-     * isn't implemented here yet
+     * These two fields hold the size of the underlying chardev.
+     * When it resized, the guest is notified by a control message
+     * if multiport is enabled, or by a config space update if not.
      */
     uint16_t cols;
     uint16_t rows;
@@ -165,6 +167,11 @@ int virtio_serial_open(VirtIOSerialPort *port);
 int virtio_serial_close(VirtIOSerialPort *port);
 
 /*
+ * Notify resize to the guest
+ */
+void virtio_serial_resize_console(VirtIOSerialPort *port, int rows, int cols);
+
+/*
  * Send data to Guest
  */
 ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf,
-- 
1.6.2.5