virtio: console: Add ability to hot-unplug ports

Remove port data; deregister from the hvc core if it's a console port. Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

virtio: console: Add ability to hot-unplug ports
Remove port data; deregister from the hvc core if it's a console port. Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Amit Shah · Rusty Russell
1 parent 7f5d810dac
Showing 2 changed files with 64 additions and 2 deletions Side-by-side Diff
drivers/char/virtio_console.c
include/linux/virtio_console.h
@@ -783,6 +783,36 @@
 	.attrs = port_sysfs_entries,
 };
  
+/* Remove all port-specific data. */
+static int remove_port(struct port *port)
+{
+	spin_lock_irq(&port->portdev->ports_lock);
+	list_del(&port->list);
+	spin_unlock_irq(&port->portdev->ports_lock);
+
+	if (is_console_port(port)) {
+		spin_lock_irq(&pdrvdata_lock);
+		list_del(&port->cons.list);
+		spin_unlock_irq(&pdrvdata_lock);
+		hvc_remove(port->cons.hvc);
+	}
+	if (port->guest_connected)
+		send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
+
+	while (port->in_vq->vq_ops->detach_unused_buf(port->in_vq))
+		;
+
+	sysfs_remove_group(&port->dev->kobj, &port_attribute_group);
+	device_destroy(pdrvdata.class, port->dev->devt);
+	cdev_del(&port->cdev);
+
+	discard_port_data(port);
+	kfree(port->name);
+
+	kfree(port);
+	return 0;
+}
+
 /* Any private messages that the Host and Guest want to share */
 static void handle_control_message(struct ports_device *portdev,
 				   struct port_buffer *buf)
@@ -854,6 +884,32 @@
 				err);
  
 		break;
+	case VIRTIO_CONSOLE_PORT_REMOVE:
+		/*
+		 * Hot unplug the port.  We don't decrement nr_ports
+		 * since we don't want to deal with extra complexities
+		 * of using the lowest-available port id: We can just
+		 * pick up the nr_ports number as the id and not have
+		 * userspace send it to us.  This helps us in two
+		 * ways:
+		 *
+		 * - We don't need to have a 'port_id' field in the
+		 *   config space when a port is hot-added.  This is a
+		 *   good thing as we might queue up multiple hotplug
+		 *   requests issued in our workqueue.
+		 *
+		 * - Another way to deal with this would have been to
+		 *   use a bitmap of the active ports and select the
+		 *   lowest non-active port from that map.  That
+		 *   bloats the already tight config space and we
+		 *   would end up artificially limiting the
+		 *   max. number of ports to sizeof(bitmap).  Right
+		 *   now we can support 2^32 ports (as the port id is
+		 *   stored in a u32 type).
+		 *
+		 */
+		remove_port(port);
+		break;
 	}
 }
  
  
@@ -1078,12 +1134,17 @@
 		/*
 		 * Port 0 got hot-added.  Since we already did all the
 		 * other initialisation for it, just tell the Host
-		 * that the port is ready.
+		 * that the port is ready if we find the port.  In
+		 * case the port was hot-removed earlier, we call
+		 * add_port to add the port.
 		 */
 		struct port *port;
  
 		port = find_port_by_id(portdev, 0);
-		send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
+		if (!port)
+			add_port(portdev, 0);
+		else
+			send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
 		return;
 	}
 	if (virtconconf.nr_ports > portdev->config.max_nr_ports) {
@@ -41,6 +41,7 @@
 #define VIRTIO_CONSOLE_RESIZE		2
 #define VIRTIO_CONSOLE_PORT_OPEN	3
 #define VIRTIO_CONSOLE_PORT_NAME	4
+#define VIRTIO_CONSOLE_PORT_REMOVE	5
  
 #ifdef __KERNEL__
 int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int));
...	...	@@ -783,6 +783,36 @@
783	783	.attrs = port_sysfs_entries,
784	784	};
785	785
	786	+/* Remove all port-specific data. */
	787	+static int remove_port(struct port *port)
	788	+{
	789	+ spin_lock_irq(&port->portdev->ports_lock);
	790	+ list_del(&port->list);
	791	+ spin_unlock_irq(&port->portdev->ports_lock);
	792	+
	793	+ if (is_console_port(port)) {
	794	+ spin_lock_irq(&pdrvdata_lock);
	795	+ list_del(&port->cons.list);
	796	+ spin_unlock_irq(&pdrvdata_lock);
	797	+ hvc_remove(port->cons.hvc);
	798	+ }
	799	+ if (port->guest_connected)
	800	+ send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
	801	+
	802	+ while (port->in_vq->vq_ops->detach_unused_buf(port->in_vq))
	803	+ ;
	804	+
	805	+ sysfs_remove_group(&port->dev->kobj, &port_attribute_group);
	806	+ device_destroy(pdrvdata.class, port->dev->devt);
	807	+ cdev_del(&port->cdev);
	808	+
	809	+ discard_port_data(port);
	810	+ kfree(port->name);
	811	+
	812	+ kfree(port);
	813	+ return 0;
	814	+}
	815	+
786	816	/* Any private messages that the Host and Guest want to share */
787	817	static void handle_control_message(struct ports_device *portdev,
788	818	struct port_buffer *buf)
...	...	@@ -854,6 +884,32 @@
854	884	err);
855	885
856	886	break;
	887	+ case VIRTIO_CONSOLE_PORT_REMOVE:
	888	+ /*
	889	+ * Hot unplug the port. We don't decrement nr_ports
	890	+ * since we don't want to deal with extra complexities
	891	+ * of using the lowest-available port id: We can just
	892	+ * pick up the nr_ports number as the id and not have
	893	+ * userspace send it to us. This helps us in two
	894	+ * ways:
	895	+ *
	896	+ * - We don't need to have a 'port_id' field in the
	897	+ * config space when a port is hot-added. This is a
	898	+ * good thing as we might queue up multiple hotplug
	899	+ * requests issued in our workqueue.
	900	+ *
	901	+ * - Another way to deal with this would have been to
	902	+ * use a bitmap of the active ports and select the
	903	+ * lowest non-active port from that map. That
	904	+ * bloats the already tight config space and we
	905	+ * would end up artificially limiting the
	906	+ * max. number of ports to sizeof(bitmap). Right
	907	+ * now we can support 2^32 ports (as the port id is
	908	+ * stored in a u32 type).
	909	+ *
	910	+ */
	911	+ remove_port(port);
	912	+ break;
857	913	}
858	914	}
859	915
860	916
...	...	@@ -1078,12 +1134,17 @@
1078	1134	/*
1079	1135	* Port 0 got hot-added. Since we already did all the
1080	1136	* other initialisation for it, just tell the Host
1081		- * that the port is ready.
	1137	+ * that the port is ready if we find the port. In
	1138	+ * case the port was hot-removed earlier, we call
	1139	+ * add_port to add the port.
1082	1140	*/
1083	1141	struct port *port;
1084	1142
1085	1143	port = find_port_by_id(portdev, 0);
1086		- send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
	1144	+ if (!port)
	1145	+ add_port(portdev, 0);
	1146	+ else
	1147	+ send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
1087	1148	return;
1088	1149	}
1089	1150	if (virtconconf.nr_ports > portdev->config.max_nr_ports) {
...	...	@@ -41,6 +41,7 @@
41	41	#define VIRTIO_CONSOLE_RESIZE 2
42	42	#define VIRTIO_CONSOLE_PORT_OPEN 3
43	43	#define VIRTIO_CONSOLE_PORT_NAME 4
	44	+#define VIRTIO_CONSOLE_PORT_REMOVE 5
44	45
45	46	#ifdef __KERNEL__
46	47	int __init virtio_cons_early_init(int (put_chars)(u32, const char , int));