virtio: console: Handle port hot-plug

If the 'nr_ports' variable in the config space is updated to a higher
value, that means new ports have been hotplugged.

Introduce a new workqueue to handle such updates and create new ports.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 5506ff8bdf03c1cf3ccff5c9fe09d3fd68cc7f12..7c53f58c87ba2b88d2a97715e283ff621faa0865 100644 (file)
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -105,6 +105,7 @@ struct ports_device {
         * notification
         */
        struct work_struct control_work;
+       struct work_struct config_work;
 
        struct list_head ports;
 
@@ -675,11 +676,6 @@ static void resize_console(struct port *port)
        }
 }
 
-static void virtcons_apply_config(struct virtio_device *vdev)
-{
-       resize_console(find_port_by_vtermno(0));
-}
-
 /* We set the configuration at this point, since we now have a tty */
 static int notifier_add_vio(struct hvc_struct *hp, int data)
 {
@@ -928,6 +924,24 @@ static void control_intr(struct virtqueue *vq)
        schedule_work(&portdev->control_work);
 }
 
+static void config_intr(struct virtio_device *vdev)
+{
+       struct ports_device *portdev;
+
+       portdev = vdev->priv;
+       if (use_multiport(portdev)) {
+               /* Handle port hot-add */
+               schedule_work(&portdev->config_work);
+       }
+       /*
+        * We'll use this way of resizing only for legacy support.
+        * For newer userspace (VIRTIO_CONSOLE_F_MULTPORT+), use
+        * control messages to indicate console size changes so that
+        * it can be done per-port
+        */
+       resize_console(find_port_by_id(portdev, 0));
+}
+
 static void fill_queue(struct virtqueue *vq, spinlock_t *lock)
 {
        struct port_buffer *buf;
@@ -1040,6 +1054,57 @@ fail:
        return err;
 }
 
+/*
+ * The workhandler for config-space updates.
+ *
+ * This is called when ports are hot-added.
+ */
+static void config_work_handler(struct work_struct *work)
+{
+       struct virtio_console_config virtconconf;
+       struct ports_device *portdev;
+       struct virtio_device *vdev;
+       int err;
+
+       portdev = container_of(work, struct ports_device, config_work);
+
+       vdev = portdev->vdev;
+       vdev->config->get(vdev,
+                         offsetof(struct virtio_console_config, nr_ports),
+                         &virtconconf.nr_ports,
+                         sizeof(virtconconf.nr_ports));
+
+       if (portdev->config.nr_ports == virtconconf.nr_ports) {
+               /*
+                * Port 0 got hot-added.  Since we already did all the
+                * other initialisation for it, just tell the Host
+                * that the port is ready.
+                */
+               struct port *port;
+
+               port = find_port_by_id(portdev, 0);
+               send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
+               return;
+       }
+       if (virtconconf.nr_ports > portdev->config.max_nr_ports) {
+               dev_warn(&vdev->dev,
+                        "More ports specified (%u) than allowed (%u)",
+                        portdev->config.nr_ports + 1,
+                        portdev->config.max_nr_ports);
+               return;
+       }
+       if (virtconconf.nr_ports < portdev->config.nr_ports)
+               return;
+
+       /* Hot-add ports */
+       while (virtconconf.nr_ports - portdev->config.nr_ports) {
+               err = add_port(portdev, portdev->config.nr_ports);
+               if (err)
+                       break;
+               portdev->config.nr_ports++;
+       }
+}
+
 static int init_vqs(struct ports_device *portdev)
 {
        vq_callback_t **io_callbacks;
@@ -1230,6 +1295,7 @@ static int __devinit virtcons_probe(struct virtio_device *vdev)
        if (multiport) {
                spin_lock_init(&portdev->cvq_lock);
                INIT_WORK(&portdev->control_work, &control_work_handler);
+               INIT_WORK(&portdev->config_work, &config_work_handler);
 
                fill_queue(portdev->c_ivq, &portdev->cvq_lock);
        }
@@ -1266,7 +1332,7 @@ static struct virtio_driver virtio_console = {
        .driver.owner = THIS_MODULE,
        .id_table =     id_table,
        .probe =        virtcons_probe,
-       .config_changed = virtcons_apply_config,
+       .config_changed = config_intr,
 };
 
 static int __init init(void)