Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus

* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus: (44 commits)
  Add MAINTAINERS entry for virtio_console
  virtio: console: Fill ports' entire in_vq with buffers
  virtio: console: Error out if we can't allocate buffers for control queue
  virtio: console: Add ability to remove module
  virtio: console: Ensure no memleaks in case of unused buffers
  virtio: console: show error message if hvc_alloc fails for console ports
  virtio: console: Add debugfs files for each port to expose debug info
  virtio: console: Add ability to hot-unplug ports
  virtio: console: Handle port hot-plug
  virtio: console: Remove cached data on port close
  virtio: console: Register with sysfs and create a 'name' attribute for ports
  virtio: console: Ensure only one process can have a port open at a time
  virtio: console: Add file operations to ports for open/read/write/poll
  virtio: console: Associate each port with a char device
  virtio: console: Prepare for writing to userspace buffers
  virtio: console: Add a new MULTIPORT feature, support for generic ports
  virtio: console: Introduce a send_buf function for a common path for sending data to host
  virtio: console: Introduce function to hand off data from host to readers
  virtio: console: Separate out find_vqs operation into a different function
  virtio: console: Separate out console init into a new function
  ...

15 files changed, 1655 insertions, 190 deletions

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 51042f0ba7e..7eff828b211 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -243,10 +243,12 @@ static int index_to_minor(int index)
 static int __devinit virtblk_probe(struct virtio_device *vdev)
 {
 	struct virtio_blk *vblk;
+	struct request_queue *q;
 	int err;
 	u64 cap;
-	u32 v;
-	u32 blk_size, sg_elems;
+	u32 v, blk_size, sg_elems, opt_io_size;
+	u16 min_io_size;
+	u8 physical_block_exp, alignment_offset;
 
 	if (index_to_minor(index) >= 1 << MINORBITS)
 		return -ENOSPC;
@@ -293,13 +295,13 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
 		goto out_mempool;
 	}
 
-	vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
-	if (!vblk->disk->queue) {
+	q = vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
+	if (!q) {
 		err = -ENOMEM;
 		goto out_put_disk;
 	}
 
-	vblk->disk->queue->queuedata = vblk;
+	q->queuedata = vblk;
 
 	if (index < 26) {
 		sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26);
@@ -323,10 +325,10 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
 
 	/* If barriers are supported, tell block layer that queue is ordered */
 	if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH))
-		blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_DRAIN_FLUSH,
+		blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH,
 				  virtblk_prepare_flush);
 	else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER))
-		blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
+		blk_queue_ordered(q, QUEUE_ORDERED_TAG, NULL);
 
 	/* If disk is read-only in the host, the guest should obey */
 	if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
@@ -345,14 +347,14 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
 	set_capacity(vblk->disk, cap);
 
 	/* We can handle whatever the host told us to handle. */
-	blk_queue_max_phys_segments(vblk->disk->queue, vblk->sg_elems-2);
-	blk_queue_max_hw_segments(vblk->disk->queue, vblk->sg_elems-2);
+	blk_queue_max_phys_segments(q, vblk->sg_elems-2);
+	blk_queue_max_hw_segments(q, vblk->sg_elems-2);
 
 	/* No need to bounce any requests */
-	blk_queue_bounce_limit(vblk->disk->queue, BLK_BOUNCE_ANY);
+	blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
 
 	/* No real sector limit. */
-	blk_queue_max_sectors(vblk->disk->queue, -1U);
+	blk_queue_max_sectors(q, -1U);
 
 	/* Host can optionally specify maximum segment size and number of
 	 * segments. */
@@ -360,16 +362,45 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
 				offsetof(struct virtio_blk_config, size_max),
 				&v);
 	if (!err)
-		blk_queue_max_segment_size(vblk->disk->queue, v);
+		blk_queue_max_segment_size(q, v);
 	else
-		blk_queue_max_segment_size(vblk->disk->queue, -1U);
+		blk_queue_max_segment_size(q, -1U);
 
 	/* Host can optionally specify the block size of the device */
 	err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE,
 				offsetof(struct virtio_blk_config, blk_size),
 				&blk_size);
 	if (!err)
-		blk_queue_logical_block_size(vblk->disk->queue, blk_size);
+		blk_queue_logical_block_size(q, blk_size);
+	else
+		blk_size = queue_logical_block_size(q);
+
+	/* Use topology information if available */
+	err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
+			offsetof(struct virtio_blk_config, physical_block_exp),
+			&physical_block_exp);
+	if (!err && physical_block_exp)
+		blk_queue_physical_block_size(q,
+				blk_size * (1 << physical_block_exp));
+
+	err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
+			offsetof(struct virtio_blk_config, alignment_offset),
+			&alignment_offset);
+	if (!err && alignment_offset)
+		blk_queue_alignment_offset(q, blk_size * alignment_offset);
+
+	err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
+			offsetof(struct virtio_blk_config, min_io_size),
+			&min_io_size);
+	if (!err && min_io_size)
+		blk_queue_io_min(q, blk_size * min_io_size);
+
+	err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
+			offsetof(struct virtio_blk_config, opt_io_size),
+			&opt_io_size);
+	if (!err && opt_io_size)
+		blk_queue_io_opt(q, blk_size * opt_io_size);
+
 
 	add_disk(vblk->disk);
 	return 0;
@@ -412,7 +443,7 @@ static struct virtio_device_id id_table[] = {
 static unsigned int features[] = {
 	VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX,
 	VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
-	VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_FLUSH
+	VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY
 };
 
 /*
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index e023682be2c..3141dd3b6e5 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -666,6 +666,14 @@ config VIRTIO_CONSOLE
 	help
 	  Virtio console for use with lguest and other hypervisors.
 
+	  Also serves as a general-purpose serial device for data
+	  transfer between the guest and host.  Character devices at
+	  /dev/vportNpn will be created when corresponding ports are
+	  found, where N is the device number and n is the port number
+	  within that device.  If specified by the host, a sysfs
+	  attribute called 'name' will be populated with a name for
+	  the port which can be used by udev scripts to create a
+	  symlink to the device.
 
 config HVCS
 	tristate "IBM Hypervisor Virtual Console Server support"
diff --git a/drivers/char/hvc_beat.c b/drivers/char/hvc_beat.c
index 0afc8b82212..6913fc33270 100644
--- a/drivers/char/hvc_beat.c
+++ b/drivers/char/hvc_beat.c
@@ -84,7 +84,7 @@ static int hvc_beat_put_chars(uint32_t vtermno, const char *buf, int cnt)
 	return cnt;
 }
 
-static struct hv_ops hvc_beat_get_put_ops = {
+static const struct hv_ops hvc_beat_get_put_ops = {
 	.get_chars = hvc_beat_get_chars,
 	.put_chars = hvc_beat_put_chars,
 };
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index 416d3423150..d8dac5820f0 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -125,7 +125,7 @@ static struct hvc_struct *hvc_get_by_index(int index)
  * console interfaces but can still be used as a tty device.  This has to be
  * static because kmalloc will not work during early console init.
  */
-static struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
+static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
 	{[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
 
@@ -247,7 +247,7 @@ static void destroy_hvc_struct(struct kref *kref)
  * vty adapters do NOT get an hvc_instantiate() callback since they
  * appear after early console init.
  */
-int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops)
+int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
 {
 	struct hvc_struct *hp;
 
@@ -749,7 +749,8 @@ static const struct tty_operations hvc_ops = {
 };
 
 struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int data,
-					struct hv_ops *ops, int outbuf_size)
+				       const struct hv_ops *ops,
+				       int outbuf_size)
 {
 	struct hvc_struct *hp;
 	int i;
diff --git a/drivers/char/hvc_console.h b/drivers/char/hvc_console.h
index 10950ca706d..52ddf4d3716 100644
--- a/drivers/char/hvc_console.h
+++ b/drivers/char/hvc_console.h
@@ -55,7 +55,7 @@ struct hvc_struct {
 	int outbuf_size;
 	int n_outbuf;
 	uint32_t vtermno;
-	struct hv_ops *ops;
+	const struct hv_ops *ops;
 	int irq_requested;
 	int data;
 	struct winsize ws;
@@ -76,11 +76,12 @@ struct hv_ops {
 };
 
 /* Register a vterm and a slot index for use as a console (console_init) */
-extern int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops);
+extern int hvc_instantiate(uint32_t vtermno, int index,
+			   const struct hv_ops *ops);
 
 /* register a vterm for hvc tty operation (module_init or hotplug add) */
 extern struct hvc_struct * __devinit hvc_alloc(uint32_t vtermno, int data,
-				struct hv_ops *ops, int outbuf_size);
+				const struct hv_ops *ops, int outbuf_size);
 /* remove a vterm from hvc tty operation (module_exit or hotplug remove) */
 extern int hvc_remove(struct hvc_struct *hp);
 
diff --git a/drivers/char/hvc_iseries.c b/drivers/char/hvc_iseries.c
index 936d05bf37f..fd0242676a2 100644
--- a/drivers/char/hvc_iseries.c
+++ b/drivers/char/hvc_iseries.c
@@ -197,7 +197,7 @@ done:
 	return sent;
 }
 
-static struct hv_ops hvc_get_put_ops = {
+static const struct hv_ops hvc_get_put_ops = {
 	.get_chars = get_chars,
 	.put_chars = put_chars,
 	.notifier_add = notifier_add_irq,
diff --git a/drivers/char/hvc_iucv.c b/drivers/char/hvc_iucv.c
index fe62bd0e17b..21681a81cc3 100644
--- a/drivers/char/hvc_iucv.c
+++ b/drivers/char/hvc_iucv.c
@@ -922,7 +922,7 @@ static int hvc_iucv_pm_restore_thaw(struct device *dev)
 
 
 /* HVC operations */
-static struct hv_ops hvc_iucv_ops = {
+static const struct hv_ops hvc_iucv_ops = {
 	.get_chars = hvc_iucv_get_chars,
 	.put_chars = hvc_iucv_put_chars,
 	.notifier_add = hvc_iucv_notifier_add,
diff --git a/drivers/char/hvc_rtas.c b/drivers/char/hvc_rtas.c
index 88590d04004..61c4a61558d 100644
--- a/drivers/char/hvc_rtas.c
+++ b/drivers/char/hvc_rtas.c
@@ -71,7 +71,7 @@ static int hvc_rtas_read_console(uint32_t vtermno, char *buf, int count)
 	return i;
 }
 
-static struct hv_ops hvc_rtas_get_put_ops = {
+static const struct hv_ops hvc_rtas_get_put_ops = {
 	.get_chars = hvc_rtas_read_console,
 	.put_chars = hvc_rtas_write_console,
 };
diff --git a/drivers/char/hvc_udbg.c b/drivers/char/hvc_udbg.c
index bd63ba878a5..b0957e61a7b 100644
--- a/drivers/char/hvc_udbg.c
+++ b/drivers/char/hvc_udbg.c
@@ -58,7 +58,7 @@ static int hvc_udbg_get(uint32_t vtermno, char *buf, int count)
 	return i;
 }
 
-static struct hv_ops hvc_udbg_ops = {
+static const struct hv_ops hvc_udbg_ops = {
 	.get_chars = hvc_udbg_get,
 	.put_chars = hvc_udbg_put,
 };
diff --git a/drivers/char/hvc_vio.c b/drivers/char/hvc_vio.c
index 10be343d6ae..27370e99c66 100644
--- a/drivers/char/hvc_vio.c
+++ b/drivers/char/hvc_vio.c
@@ -77,7 +77,7 @@ static int filtered_get_chars(uint32_t vtermno, char *buf, int count)
 	return got;
 }
 
-static struct hv_ops hvc_get_put_ops = {
+static const struct hv_ops hvc_get_put_ops = {
 	.get_chars = filtered_get_chars,
 	.put_chars = hvc_put_chars,
 	.notifier_add = notifier_add_irq,
diff --git a/drivers/char/hvc_xen.c b/drivers/char/hvc_xen.c
index b1a71638c77..60446f82a3f 100644
--- a/drivers/char/hvc_xen.c
+++ b/drivers/char/hvc_xen.c
@@ -122,7 +122,7 @@ static int read_console(uint32_t vtermno, char *buf, int len)
 	return recv;
 }
 
-static struct hv_ops hvc_ops = {
+static const struct hv_ops hvc_ops = {
 	.get_chars = read_console,
 	.put_chars = write_console,
 	.notifier_add = notifier_add_irq,
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index a035ae39a35..213373b5f17 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1,18 +1,6 @@
-/*D:300
- * The Guest console driver
- *
- * Writing console drivers is one of the few remaining Dark Arts in Linux.
- * Fortunately for us, the path of virtual consoles has been well-trodden by
- * the PowerPC folks, who wrote "hvc_console.c" to generically support any
- * virtual console.  We use that infrastructure which only requires us to write
- * the basic put_chars and get_chars functions and call the right register
- * functions.
- :*/
-
-/*M:002 The console can be flooded: while the Guest is processing input the
- * Host can send more.  Buffering in the Host could alleviate this, but it is a
- * difficult problem in general. :*/
-/* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
+/*
+ * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
+ * Copyright (C) 2009, 2010 Red Hat, Inc.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -28,142 +16,694 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
+#include <linux/cdev.h>
+#include <linux/debugfs.h>
+#include <linux/device.h>
 #include <linux/err.h>
+#include <linux/fs.h>
 #include <linux/init.h>
+#include <linux/list.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
 #include <linux/virtio.h>
 #include <linux/virtio_console.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
 #include "hvc_console.h"
 
-/*D:340 These represent our input and output console queues, and the virtio
- * operations for them. */
-static struct virtqueue *in_vq, *out_vq;
-static struct virtio_device *vdev;
+/*
+ * This is a global struct for storing common data for all the devices
+ * this driver handles.
+ *
+ * Mainly, it has a linked list for all the consoles in one place so
+ * that callbacks from hvc for get_chars(), put_chars() work properly
+ * across multiple devices and multiple ports per device.
+ */
+struct ports_driver_data {
+	/* Used for registering chardevs */
+	struct class *class;
+
+	/* Used for exporting per-port information to debugfs */
+	struct dentry *debugfs_dir;
+
+	/* Number of devices this driver is handling */
+	unsigned int index;
+
+	/*
+	 * This is used to keep track of the number of hvc consoles
+	 * spawned by this driver.  This number is given as the first
+	 * argument to hvc_alloc().  To correctly map an initial
+	 * console spawned via hvc_instantiate to the console being
+	 * hooked up via hvc_alloc, we need to pass the same vtermno.
+	 *
+	 * We also just assume the first console being initialised was
+	 * the first one that got used as the initial console.
+	 */
+	unsigned int next_vtermno;
+
+	/* All the console devices handled by this driver */
+	struct list_head consoles;
+};
+static struct ports_driver_data pdrvdata;
+
+DEFINE_SPINLOCK(pdrvdata_lock);
+
+/* This struct holds information that's relevant only for console ports */
+struct console {
+	/* We'll place all consoles in a list in the pdrvdata struct */
+	struct list_head list;
+
+	/* The hvc device associated with this console port */
+	struct hvc_struct *hvc;
+
+	/*
+	 * This number identifies the number that we used to register
+	 * with hvc in hvc_instantiate() and hvc_alloc(); this is the
+	 * number passed on by the hvc callbacks to us to
+	 * differentiate between the other console ports handled by
+	 * this driver
+	 */
+	u32 vtermno;
+};
+
+struct port_buffer {
+	char *buf;
+
+	/* size of the buffer in *buf above */
+	size_t size;
+
+	/* used length of the buffer */
+	size_t len;
+	/* offset in the buf from which to consume data */
+	size_t offset;
+};
+
+/*
+ * This is a per-device struct that stores data common to all the
+ * ports for that device (vdev->priv).
+ */
+struct ports_device {
+	/*
+	 * Workqueue handlers where we process deferred work after
+	 * notification
+	 */
+	struct work_struct control_work;
+	struct work_struct config_work;
+
+	struct list_head ports;
+
+	/* To protect the list of ports */
+	spinlock_t ports_lock;
+
+	/* To protect the vq operations for the control channel */
+	spinlock_t cvq_lock;
+
+	/* The current config space is stored here */
+	struct virtio_console_config config;
+
+	/* The virtio device we're associated with */
+	struct virtio_device *vdev;
+
+	/*
+	 * A couple of virtqueues for the control channel: one for
+	 * guest->host transfers, one for host->guest transfers
+	 */
+	struct virtqueue *c_ivq, *c_ovq;
+
+	/* Array of per-port IO virtqueues */
+	struct virtqueue **in_vqs, **out_vqs;
+
+	/* Used for numbering devices for sysfs and debugfs */
+	unsigned int drv_index;
+
+	/* Major number for this device.  Ports will be created as minors. */
+	int chr_major;
+};
+
+/* This struct holds the per-port data */
+struct port {
+	/* Next port in the list, head is in the ports_device */
+	struct list_head list;
+
+	/* Pointer to the parent virtio_console device */
+	struct ports_device *portdev;
+
+	/* The current buffer from which data has to be fed to readers */
+	struct port_buffer *inbuf;
+
+	/*
+	 * To protect the operations on the in_vq associated with this
+	 * port.  Has to be a spinlock because it can be called from
+	 * interrupt context (get_char()).
+	 */
+	spinlock_t inbuf_lock;
+
+	/* The IO vqs for this port */
+	struct virtqueue *in_vq, *out_vq;
+
+	/* File in the debugfs directory that exposes this port's information */
+	struct dentry *debugfs_file;
+
+	/*
+	 * The entries in this struct will be valid if this port is
+	 * hooked up to an hvc console
+	 */
+	struct console cons;
+
+	/* Each port associates with a separate char device */
+	struct cdev cdev;
+	struct device *dev;
+
+	/* A waitqueue for poll() or blocking read operations */
+	wait_queue_head_t waitqueue;
+
+	/* The 'name' of the port that we expose via sysfs properties */
+	char *name;
+
+	/* The 'id' to identify the port with the Host */
+	u32 id;
+
+	/* Is the host device open */
+	bool host_connected;
+
+	/* We should allow only one process to open a port */
+	bool guest_connected;
+};
+
+/* This is the very early arch-specified put chars function. */
+static int (*early_put_chars)(u32, const char *, int);
+
+static struct port *find_port_by_vtermno(u32 vtermno)
+{
+	struct port *port;
+	struct console *cons;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pdrvdata_lock, flags);
+	list_for_each_entry(cons, &pdrvdata.consoles, list) {
+		if (cons->vtermno == vtermno) {
+			port = container_of(cons, struct port, cons);
+			goto out;
+		}
+	}
+	port = NULL;
+out:
+	spin_unlock_irqrestore(&pdrvdata_lock, flags);
+	return port;
+}
+
+static struct port *find_port_by_id(struct ports_device *portdev, u32 id)
+{
+	struct port *port;
+	unsigned long flags;
+
+	spin_lock_irqsave(&portdev->ports_lock, flags);
+	list_for_each_entry(port, &portdev->ports, list)
+		if (port->id == id)
+			goto out;
+	port = NULL;
+out:
+	spin_unlock_irqrestore(&portdev->ports_lock, flags);
+
+	return port;
+}
+
+static struct port *find_port_by_vq(struct ports_device *portdev,
+				    struct virtqueue *vq)
+{
+	struct port *port;
+	unsigned long flags;
+
+	spin_lock_irqsave(&portdev->ports_lock, flags);
+	list_for_each_entry(port, &portdev->ports, list)
+		if (port->in_vq == vq || port->out_vq == vq)
+			goto out;
+	port = NULL;
+out:
+	spin_unlock_irqrestore(&portdev->ports_lock, flags);
+	return port;
+}
+
+static bool is_console_port(struct port *port)
+{
+	if (port->cons.hvc)
+		return true;
+	return false;
+}
+
+static inline bool use_multiport(struct ports_device *portdev)
+{
+	/*
+	 * This condition can be true when put_chars is called from
+	 * early_init
+	 */
+	if (!portdev->vdev)
+		return 0;
+	return portdev->vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+}
 
-/* This is our input buffer, and how much data is left in it. */
-static unsigned int in_len;
-static char *in, *inbuf;
+static void free_buf(struct port_buffer *buf)
+{
+	kfree(buf->buf);
+	kfree(buf);
+}
+
+static struct port_buffer *alloc_buf(size_t buf_size)
+{
+	struct port_buffer *buf;
 
-/* The operations for our console. */
-static struct hv_ops virtio_cons;
+	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
+	if (!buf)
+		goto fail;
+	buf->buf = kzalloc(buf_size, GFP_KERNEL);
+	if (!buf->buf)
+		goto free_buf;
+	buf->len = 0;
+	buf->offset = 0;
+	buf->size = buf_size;
+	return buf;
+
+free_buf:
+	kfree(buf);
+fail:
+	return NULL;
+}
+
+/* Callers should take appropriate locks */
+static void *get_inbuf(struct port *port)
+{
+	struct port_buffer *buf;
+	struct virtqueue *vq;
+	unsigned int len;
 
-/* The hvc device */
-static struct hvc_struct *hvc;
+	vq = port->in_vq;
+	buf = vq->vq_ops->get_buf(vq, &len);
+	if (buf) {
+		buf->len = len;
+		buf->offset = 0;
+	}
+	return buf;
+}
 
-/*D:310 The put_chars() callback is pretty straightforward.
+/*
+ * Create a scatter-gather list representing our input buffer and put
+ * it in the queue.
  *
- * We turn the characters into a scatter-gather list, add it to the output
- * queue and then kick the Host.  Then we sit here waiting for it to finish:
- * inefficient in theory, but in practice implementations will do it
- * immediately (lguest's Launcher does). */
-static int put_chars(u32 vtermno, const char *buf, int count)
+ * Callers should take appropriate locks.
+ */
+static int add_inbuf(struct virtqueue *vq, struct port_buffer *buf)
 {
 	struct scatterlist sg[1];
+	int ret;
+
+	sg_init_one(sg, buf->buf, buf->size);
+
+	ret = vq->vq_ops->add_buf(vq, sg, 0, 1, buf);
+	vq->vq_ops->kick(vq);
+	return ret;
+}
+
+/* Discard any unread data this port has. Callers lockers. */
+static void discard_port_data(struct port *port)
+{
+	struct port_buffer *buf;
+	struct virtqueue *vq;
 	unsigned int len;
+	int ret;
 
-	/* This is a convenient routine to initialize a single-elem sg list */
-	sg_init_one(sg, buf, count);
+	vq = port->in_vq;
+	if (port->inbuf)
+		buf = port->inbuf;
+	else
+		buf = vq->vq_ops->get_buf(vq, &len);
 
-	/* add_buf wants a token to identify this buffer: we hand it any
-	 * non-NULL pointer, since there's only ever one buffer. */
-	if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) {
-		/* Tell Host to go! */
-		out_vq->vq_ops->kick(out_vq);
-		/* Chill out until it's done with the buffer. */
-		while (!out_vq->vq_ops->get_buf(out_vq, &len))
-			cpu_relax();
+	ret = 0;
+	while (buf) {
+		if (add_inbuf(vq, buf) < 0) {
+			ret++;
+			free_buf(buf);
+		}
+		buf = vq->vq_ops->get_buf(vq, &len);
 	}
+	port->inbuf = NULL;
+	if (ret)
+		dev_warn(port->dev, "Errors adding %d buffers back to vq\n",
+			 ret);
+}
 
-	/* We're expected to return the amount of data we wrote: all of it. */
-	return count;
+static bool port_has_data(struct port *port)
+{
+	unsigned long flags;
+	bool ret;
+
+	spin_lock_irqsave(&port->inbuf_lock, flags);
+	if (port->inbuf) {
+		ret = true;
+		goto out;
+	}
+	port->inbuf = get_inbuf(port);
+	if (port->inbuf) {
+		ret = true;
+		goto out;
+	}
+	ret = false;
+out:
+	spin_unlock_irqrestore(&port->inbuf_lock, flags);
+	return ret;
 }
 
-/* Create a scatter-gather list representing our input buffer and put it in the
- * queue. */
-static void add_inbuf(void)
+static ssize_t send_control_msg(struct port *port, unsigned int event,
+				unsigned int value)
 {
 	struct scatterlist sg[1];
-	sg_init_one(sg, inbuf, PAGE_SIZE);
+	struct virtio_console_control cpkt;
+	struct virtqueue *vq;
+	int len;
+
+	if (!use_multiport(port->portdev))
+		return 0;
+
+	cpkt.id = port->id;
+	cpkt.event = event;
+	cpkt.value = value;
+
+	vq = port->portdev->c_ovq;
 
-	/* We should always be able to add one buffer to an empty queue. */
-	if (in_vq->vq_ops->add_buf(in_vq, sg, 0, 1, inbuf) < 0)
-		BUG();
-	in_vq->vq_ops->kick(in_vq);
+	sg_init_one(sg, &cpkt, sizeof(cpkt));
+	if (vq->vq_ops->add_buf(vq, sg, 1, 0, &cpkt) >= 0) {
+		vq->vq_ops->kick(vq);
+		while (!vq->vq_ops->get_buf(vq, &len))
+			cpu_relax();
+	}
+	return 0;
 }
 
-/*D:350 get_chars() is the callback from the hvc_console infrastructure when
- * an interrupt is received.
- *
- * Most of the code deals with the fact that the hvc_console() infrastructure
- * only asks us for 16 bytes at a time.  We keep in_offset and in_used fields
- * for partially-filled buffers. */
-static int get_chars(u32 vtermno, char *buf, int count)
+static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count)
 {
-	/* If we don't have an input queue yet, we can't get input. */
-	BUG_ON(!in_vq);
+	struct scatterlist sg[1];
+	struct virtqueue *out_vq;
+	ssize_t ret;
+	unsigned int len;
+
+	out_vq = port->out_vq;
+
+	sg_init_one(sg, in_buf, in_count);
+	ret = out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, in_buf);
+
+	/* Tell Host to go! */
+	out_vq->vq_ops->kick(out_vq);
+
+	if (ret < 0) {
+		len = 0;
+		goto fail;
+	}
+
+	/*
+	 * Wait till the host acknowledges it pushed out the data we
+	 * sent. Also ensure we return to userspace the number of
+	 * bytes that were successfully consumed by the host.
+	 */
+	while (!out_vq->vq_ops->get_buf(out_vq, &len))
+		cpu_relax();
+fail:
+	/* We're expected to return the amount of data we wrote */
+	return len;
+}
+
+/*
+ * Give out the data that's requested from the buffer that we have
+ * queued up.
+ */
+static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,
+			    bool to_user)
+{
+	struct port_buffer *buf;
+	unsigned long flags;
+
+	if (!out_count || !port_has_data(port))
+		return 0;
+
+	buf = port->inbuf;
+	out_count = min(out_count, buf->len - buf->offset);
+
+	if (to_user) {
+		ssize_t ret;
+
+		ret = copy_to_user(out_buf, buf->buf + buf->offset, out_count);
+		if (ret)
+			return -EFAULT;
+	} else {
+		memcpy(out_buf, buf->buf + buf->offset, out_count);
+	}
+
+	buf->offset += out_count;
+
+	if (buf->offset == buf->len) {
+		/*
+		 * We're done using all the data in this buffer.
+		 * Re-queue so that the Host can send us more data.
+		 */
+		spin_lock_irqsave(&port->inbuf_lock, flags);
+		port->inbuf = NULL;
+
+		if (add_inbuf(port->in_vq, buf) < 0)
+			dev_warn(port->dev, "failed add_buf\n");
+
+		spin_unlock_irqrestore(&port->inbuf_lock, flags);
+	}
+	/* Return the number of bytes actually copied */
+	return out_count;
+}
 
-	/* No buffer?  Try to get one. */
-	if (!in_len) {
-		in = in_vq->vq_ops->get_buf(in_vq, &in_len);
-		if (!in)
+/* The condition that must be true for polling to end */
+static bool wait_is_over(struct port *port)
+{
+	return port_has_data(port) || !port->host_connected;
+}
+
+static ssize_t port_fops_read(struct file *filp, char __user *ubuf,
+			      size_t count, loff_t *offp)
+{
+	struct port *port;
+	ssize_t ret;
+
+	port = filp->private_data;
+
+	if (!port_has_data(port)) {
+		/*
+		 * If nothing's connected on the host just return 0 in
+		 * case of list_empty; this tells the userspace app
+		 * that there's no connection
+		 */
+		if (!port->host_connected)
 			return 0;
+		if (filp->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+
+		ret = wait_event_interruptible(port->waitqueue,
+					       wait_is_over(port));
+		if (ret < 0)
+			return ret;
+	}
+	/*
+	 * We could've received a disconnection message while we were
+	 * waiting for more data.
+	 *
+	 * This check is not clubbed in the if() statement above as we
+	 * might receive some data as well as the host could get
+	 * disconnected after we got woken up from our wait.  So we
+	 * really want to give off whatever data we have and only then
+	 * check for host_connected.
+	 */
+	if (!port_has_data(port) && !port->host_connected)
+		return 0;
+
+	return fill_readbuf(port, ubuf, count, true);
+}
+
+static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
+			       size_t count, loff_t *offp)
+{
+	struct port *port;
+	char *buf;
+	ssize_t ret;
+
+	port = filp->private_data;
+
+	count = min((size_t)(32 * 1024), count);
+
+	buf = kmalloc(count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = copy_from_user(buf, ubuf, count);
+	if (ret) {
+		ret = -EFAULT;
+		goto free_buf;
 	}
 
-	/* You want more than we have to give?  Well, try wanting less! */
-	if (in_len < count)
-		count = in_len;
+	ret = send_buf(port, buf, count);
+free_buf:
+	kfree(buf);
+	return ret;
+}
+
+static unsigned int port_fops_poll(struct file *filp, poll_table *wait)
+{
+	struct port *port;
+	unsigned int ret;
+
+	port = filp->private_data;
+	poll_wait(filp, &port->waitqueue, wait);
+
+	ret = 0;
+	if (port->inbuf)
+		ret |= POLLIN | POLLRDNORM;
+	if (port->host_connected)
+		ret |= POLLOUT;
+	if (!port->host_connected)
+		ret |= POLLHUP;
+
+	return ret;
+}
+
+static int port_fops_release(struct inode *inode, struct file *filp)
+{
+	struct port *port;
+
+	port = filp->private_data;
+
+	/* Notify host of port being closed */
+	send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
+
+	spin_lock_irq(&port->inbuf_lock);
+	port->guest_connected = false;
+
+	discard_port_data(port);
+
+	spin_unlock_irq(&port->inbuf_lock);
+
+	return 0;
+}
+
+static int port_fops_open(struct inode *inode, struct file *filp)
+{
+	struct cdev *cdev = inode->i_cdev;
+	struct port *port;
+
+	port = container_of(cdev, struct port, cdev);
+	filp->private_data = port;
+
+	/*
+	 * Don't allow opening of console port devices -- that's done
+	 * via /dev/hvc
+	 */
+	if (is_console_port(port))
+		return -ENXIO;
+
+	/* Allow only one process to open a particular port at a time */
+	spin_lock_irq(&port->inbuf_lock);
+	if (port->guest_connected) {
+		spin_unlock_irq(&port->inbuf_lock);
+		return -EMFILE;
+	}
 
-	/* Copy across to their buffer and increment offset. */
-	memcpy(buf, in, count);
-	in += count;
-	in_len -= count;
+	port->guest_connected = true;
+	spin_unlock_irq(&port->inbuf_lock);
 
-	/* Finished?  Re-register buffer so Host will use it again. */
-	if (in_len == 0)
-		add_inbuf();
+	/* Notify host of port being opened */
+	send_control_msg(filp->private_data, VIRTIO_CONSOLE_PORT_OPEN, 1);
 
-	return count;
+	return 0;
 }
-/*:*/
 
-/*D:320 Console drivers are initialized very early so boot messages can go out,
- * so we do things slightly differently from the generic virtio initialization
- * of the net and block drivers.
+/*
+ * The file operations that we support: programs in the guest can open
+ * a console device, read from it, write to it, poll for data and
+ * close it.  The devices are at
+ *   /dev/vport<device number>p<port number>
+ */
+static const struct file_operations port_fops = {
+	.owner = THIS_MODULE,
+	.open  = port_fops_open,
+	.read  = port_fops_read,
+	.write = port_fops_write,
+	.poll  = port_fops_poll,
+	.release = port_fops_release,
+};
+
+/*
+ * The put_chars() callback is pretty straightforward.
  *
- * At this stage, the console is output-only.  It's too early to set up a
- * virtqueue, so we let the drivers do some boutique early-output thing. */
-int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
+ * We turn the characters into a scatter-gather list, add it to the
+ * output queue and then kick the Host.  Then we sit here waiting for
+ * it to finish: inefficient in theory, but in practice
+ * implementations will do it immediately (lguest's Launcher does).
+ */
+static int put_chars(u32 vtermno, const char *buf, int count)
 {
-	virtio_cons.put_chars = put_chars;
-	return hvc_instantiate(0, 0, &virtio_cons);
+	struct port *port;
+
+	port = find_port_by_vtermno(vtermno);
+	if (!port)
+		return 0;
+
+	if (unlikely(early_put_chars))
+		return early_put_chars(vtermno, buf, count);
+
+	return send_buf(port, (void *)buf, count);
 }
 
 /*
- * virtio console configuration. This supports:
- * - console resize
+ * get_chars() is the callback from the hvc_console infrastructure
+ * when an interrupt is received.
+ *
+ * We call out to fill_readbuf that gets us the required data from the
+ * buffers that are queued up.
  */
-static void virtcons_apply_config(struct virtio_device *dev)
+static int get_chars(u32 vtermno, char *buf, int count)
 {
+	struct port *port;
+
+	port = find_port_by_vtermno(vtermno);
+	if (!port)
+		return 0;
+
+	/* If we don't have an input queue yet, we can't get input. */
+	BUG_ON(!port->in_vq);
+
+	return fill_readbuf(port, buf, count, false);
+}
+
+static void resize_console(struct port *port)
+{
+	struct virtio_device *vdev;
 	struct winsize ws;
 
-	if (virtio_has_feature(dev, VIRTIO_CONSOLE_F_SIZE)) {
-		dev->config->get(dev,
-				 offsetof(struct virtio_console_config, cols),
-				 &ws.ws_col, sizeof(u16));
-		dev->config->get(dev,
-				 offsetof(struct virtio_console_config, rows),
-				 &ws.ws_row, sizeof(u16));
-		hvc_resize(hvc, ws);
+	vdev = port->portdev->vdev;
+	if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE)) {
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_console_config, cols),
+				  &ws.ws_col, sizeof(u16));
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_console_config, rows),
+				  &ws.ws_row, sizeof(u16));
+		hvc_resize(port->cons.hvc, ws);
 	}
 }
 
-/*
- * we support only one console, the hvc struct is a global var
- * We set the configuration at this point, since we now have a tty
- */
+/* We set the configuration at this point, since we now have a tty */
 static int notifier_add_vio(struct hvc_struct *hp, int data)
 {
+	struct port *port;
+
+	port = find_port_by_vtermno(hp->vtermno);
+	if (!port)
+		return -EINVAL;
+
 	hp->irq_requested = 1;
-	virtcons_apply_config(vdev);
+	resize_console(port);
 
 	return 0;
 }
@@ -173,79 +713,797 @@ static void notifier_del_vio(struct hvc_struct *hp, int data)
 	hp->irq_requested = 0;
 }
 
-static void hvc_handle_input(struct virtqueue *vq)
+/* The operations for console ports. */
+static const struct hv_ops hv_ops = {
+	.get_chars = get_chars,
+	.put_chars = put_chars,
+	.notifier_add = notifier_add_vio,
+	.notifier_del = notifier_del_vio,
+	.notifier_hangup = notifier_del_vio,
+};
+
+/*
+ * Console drivers are initialized very early so boot messages can go
+ * out, so we do things slightly differently from the generic virtio
+ * initialization of the net and block drivers.
+ *
+ * At this stage, the console is output-only.  It's too early to set
+ * up a virtqueue, so we let the drivers do some boutique early-output
+ * thing.
+ */
+int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
 {
-	if (hvc_poll(hvc))
+	early_put_chars = put_chars;
+	return hvc_instantiate(0, 0, &hv_ops);
+}
+
+int init_port_console(struct port *port)
+{
+	int ret;
+
+	/*
+	 * The Host's telling us this port is a console port.  Hook it
+	 * up with an hvc console.
+	 *
+	 * To set up and manage our virtual console, we call
+	 * hvc_alloc().
+	 *
+	 * The first argument of hvc_alloc() is the virtual console
+	 * number.  The second argument is the parameter for the
+	 * notification mechanism (like irq number).  We currently
+	 * leave this as zero, virtqueues have implicit notifications.
+	 *
+	 * The third argument is a "struct hv_ops" containing the
+	 * put_chars() get_chars(), notifier_add() and notifier_del()
+	 * pointers.  The final argument is the output buffer size: we
+	 * can do any size, so we put PAGE_SIZE here.
+	 */
+	port->cons.vtermno = pdrvdata.next_vtermno;
+
+	port->cons.hvc = hvc_alloc(port->cons.vtermno, 0, &hv_ops, PAGE_SIZE);
+	if (IS_ERR(port->cons.hvc)) {
+		ret = PTR_ERR(port->cons.hvc);
+		dev_err(port->dev,
+			"error %d allocating hvc for port\n", ret);
+		port->cons.hvc = NULL;
+		return ret;
+	}
+	spin_lock_irq(&pdrvdata_lock);
+	pdrvdata.next_vtermno++;
+	list_add_tail(&port->cons.list, &pdrvdata.consoles);
+	spin_unlock_irq(&pdrvdata_lock);
+	port->guest_connected = true;
+
+	/* Notify host of port being opened */
+	send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
+
+	return 0;
+}
+
+static ssize_t show_port_name(struct device *dev,
+			      struct device_attribute *attr, char *buffer)
+{
+	struct port *port;
+
+	port = dev_get_drvdata(dev);
+
+	return sprintf(buffer, "%s\n", port->name);
+}
+
+static DEVICE_ATTR(name, S_IRUGO, show_port_name, NULL);
+
+static struct attribute *port_sysfs_entries[] = {
+	&dev_attr_name.attr,
+	NULL
+};
+
+static struct attribute_group port_attribute_group = {
+	.name = NULL,		/* put in device directory */
+	.attrs = port_sysfs_entries,
+};
+
+static int debugfs_open(struct inode *inode, struct file *filp)
+{
+	filp->private_data = inode->i_private;
+	return 0;
+}
+
+static ssize_t debugfs_read(struct file *filp, char __user *ubuf,
+			    size_t count, loff_t *offp)
+{
+	struct port *port;
+	char *buf;
+	ssize_t ret, out_offset, out_count;
+
+	out_count = 1024;
+	buf = kmalloc(out_count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	port = filp->private_data;
+	out_offset = 0;
+	out_offset += snprintf(buf + out_offset, out_count,
+			       "name: %s\n", port->name ? port->name : "");
+	out_offset += snprintf(buf + out_offset, out_count - out_offset,
+			       "guest_connected: %d\n", port->guest_connected);
+	out_offset += snprintf(buf + out_offset, out_count - out_offset,
+			       "host_connected: %d\n", port->host_connected);
+	out_offset += snprintf(buf + out_offset, out_count - out_offset,
+			       "is_console: %s\n",
+			       is_console_port(port) ? "yes" : "no");
+	out_offset += snprintf(buf + out_offset, out_count - out_offset,
+			       "console_vtermno: %u\n", port->cons.vtermno);
+
+	ret = simple_read_from_buffer(ubuf, count, offp, buf, out_offset);
+	kfree(buf);
+	return ret;
+}
+
+static const struct file_operations port_debugfs_ops = {
+	.owner = THIS_MODULE,
+	.open  = debugfs_open,
+	.read  = debugfs_read,
+};
+
+/* Remove all port-specific data. */
+static int remove_port(struct port *port)
+{
+	struct port_buffer *buf;
+
+	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);
+
+	sysfs_remove_group(&port->dev->kobj, &port_attribute_group);
+	device_destroy(pdrvdata.class, port->dev->devt);
+	cdev_del(&port->cdev);
+
+	/* Remove unused data this port might have received. */
+	discard_port_data(port);
+
+	/* Remove buffers we queued up for the Host to send us data in. */
+	while ((buf = port->in_vq->vq_ops->detach_unused_buf(port->in_vq)))
+		free_buf(buf);
+
+	kfree(port->name);
+
+	debugfs_remove(port->debugfs_file);
+
+	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)
+{
+	struct virtio_console_control *cpkt;
+	struct port *port;
+	size_t name_size;
+	int err;
+
+	cpkt = (struct virtio_console_control *)(buf->buf + buf->offset);
+
+	port = find_port_by_id(portdev, cpkt->id);
+	if (!port) {
+		/* No valid header at start of buffer.  Drop it. */
+		dev_dbg(&portdev->vdev->dev,
+			"Invalid index %u in control packet\n", cpkt->id);
+		return;
+	}
+
+	switch (cpkt->event) {
+	case VIRTIO_CONSOLE_CONSOLE_PORT:
+		if (!cpkt->value)
+			break;
+		if (is_console_port(port))
+			break;
+
+		init_port_console(port);
+		/*
+		 * Could remove the port here in case init fails - but
+		 * have to notify the host first.
+		 */
+		break;
+	case VIRTIO_CONSOLE_RESIZE:
+		if (!is_console_port(port))
+			break;
+		port->cons.hvc->irq_requested = 1;
+		resize_console(port);
+		break;
+	case VIRTIO_CONSOLE_PORT_OPEN:
+		port->host_connected = cpkt->value;
+		wake_up_interruptible(&port->waitqueue);
+		break;
+	case VIRTIO_CONSOLE_PORT_NAME:
+		/*
+		 * Skip the size of the header and the cpkt to get the size
+		 * of the name that was sent
+		 */
+		name_size = buf->len - buf->offset - sizeof(*cpkt) + 1;
+
+		port->name = kmalloc(name_size, GFP_KERNEL);
+		if (!port->name) {
+			dev_err(port->dev,
+				"Not enough space to store port name\n");
+			break;
+		}
+		strncpy(port->name, buf->buf + buf->offset + sizeof(*cpkt),
+			name_size - 1);
+		port->name[name_size - 1] = 0;
+
+		/*
+		 * Since we only have one sysfs attribute, 'name',
+		 * create it only if we have a name for the port.
+		 */
+		err = sysfs_create_group(&port->dev->kobj,
+					 &port_attribute_group);
+		if (err)
+			dev_err(port->dev,
+				"Error %d creating sysfs device attributes\n",
+				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;
+	}
+}
+
+static void control_work_handler(struct work_struct *work)
+{
+	struct ports_device *portdev;
+	struct virtqueue *vq;
+	struct port_buffer *buf;
+	unsigned int len;
+
+	portdev = container_of(work, struct ports_device, control_work);
+	vq = portdev->c_ivq;
+
+	spin_lock(&portdev->cvq_lock);
+	while ((buf = vq->vq_ops->get_buf(vq, &len))) {
+		spin_unlock(&portdev->cvq_lock);
+
+		buf->len = len;
+		buf->offset = 0;
+
+		handle_control_message(portdev, buf);
+
+		spin_lock(&portdev->cvq_lock);
+		if (add_inbuf(portdev->c_ivq, buf) < 0) {
+			dev_warn(&portdev->vdev->dev,
+				 "Error adding buffer to queue\n");
+			free_buf(buf);
+		}
+	}
+	spin_unlock(&portdev->cvq_lock);
+}
+
+static void in_intr(struct virtqueue *vq)
+{
+	struct port *port;
+	unsigned long flags;
+
+	port = find_port_by_vq(vq->vdev->priv, vq);
+	if (!port)
+		return;
+
+	spin_lock_irqsave(&port->inbuf_lock, flags);
+	if (!port->inbuf)
+		port->inbuf = get_inbuf(port);
+
+	/*
+	 * Don't queue up data when port is closed.  This condition
+	 * can be reached when a console port is not yet connected (no
+	 * tty is spawned) and the host sends out data to console
+	 * ports.  For generic serial ports, the host won't
+	 * (shouldn't) send data till the guest is connected.
+	 */
+	if (!port->guest_connected)
+		discard_port_data(port);
+
+	spin_unlock_irqrestore(&port->inbuf_lock, flags);
+
+	wake_up_interruptible(&port->waitqueue);
+
+	if (is_console_port(port) && hvc_poll(port->cons.hvc))
 		hvc_kick();
 }
 
-/*D:370 Once we're further in boot, we get probed like any other virtio device.
- * At this stage we set up the output virtqueue.
- *
- * To set up and manage our virtual console, we call hvc_alloc().  Since we
- * never remove the console device we never need this pointer again.
+static void control_intr(struct virtqueue *vq)
+{
+	struct ports_device *portdev;
+
+	portdev = vq->vdev->priv;
+	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 unsigned int fill_queue(struct virtqueue *vq, spinlock_t *lock)
+{
+	struct port_buffer *buf;
+	unsigned int ret;
+	int err;
+
+	ret = 0;
+	do {
+		buf = alloc_buf(PAGE_SIZE);
+		if (!buf)
+			break;
+
+		spin_lock_irq(lock);
+		err = add_inbuf(vq, buf);
+		if (err < 0) {
+			spin_unlock_irq(lock);
+			free_buf(buf);
+			break;
+		}
+		ret++;
+		spin_unlock_irq(lock);
+	} while (err > 0);
+
+	return ret;
+}
+
+static int add_port(struct ports_device *portdev, u32 id)
+{
+	char debugfs_name[16];
+	struct port *port;
+	struct port_buffer *buf;
+	dev_t devt;
+	int err;
+
+	port = kmalloc(sizeof(*port), GFP_KERNEL);
+	if (!port) {
+		err = -ENOMEM;
+		goto fail;
+	}
+
+	port->portdev = portdev;
+	port->id = id;
+
+	port->name = NULL;
+	port->inbuf = NULL;
+	port->cons.hvc = NULL;
+
+	port->host_connected = port->guest_connected = false;
+
+	port->in_vq = portdev->in_vqs[port->id];
+	port->out_vq = portdev->out_vqs[port->id];
+
+	cdev_init(&port->cdev, &port_fops);
+
+	devt = MKDEV(portdev->chr_major, id);
+	err = cdev_add(&port->cdev, devt, 1);
+	if (err < 0) {
+		dev_err(&port->portdev->vdev->dev,
+			"Error %d adding cdev for port %u\n", err, id);
+		goto free_port;
+	}
+	port->dev = device_create(pdrvdata.class, &port->portdev->vdev->dev,
+				  devt, port, "vport%up%u",
+				  port->portdev->drv_index, id);
+	if (IS_ERR(port->dev)) {
+		err = PTR_ERR(port->dev);
+		dev_err(&port->portdev->vdev->dev,
+			"Error %d creating device for port %u\n",
+			err, id);
+		goto free_cdev;
+	}
+
+	spin_lock_init(&port->inbuf_lock);
+	init_waitqueue_head(&port->waitqueue);
+
+	/* Fill the in_vq with buffers so the host can send us data. */
+	err = fill_queue(port->in_vq, &port->inbuf_lock);
+	if (!err) {
+		dev_err(port->dev, "Error allocating inbufs\n");
+		err = -ENOMEM;
+		goto free_device;
+	}
+
+	/*
+	 * If we're not using multiport support, this has to be a console port
+	 */
+	if (!use_multiport(port->portdev)) {
+		err = init_port_console(port);
+		if (err)
+			goto free_inbufs;
+	}
+
+	spin_lock_irq(&portdev->ports_lock);
+	list_add_tail(&port->list, &port->portdev->ports);
+	spin_unlock_irq(&portdev->ports_lock);
+
+	/*
+	 * Tell the Host we're set so that it can send us various
+	 * configuration parameters for this port (eg, port name,
+	 * caching, whether this is a console port, etc.)
+	 */
+	send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
+
+	if (pdrvdata.debugfs_dir) {
+		/*
+		 * Finally, create the debugfs file that we can use to
+		 * inspect a port's state at any time
+		 */
+		sprintf(debugfs_name, "vport%up%u",
+			port->portdev->drv_index, id);
+		port->debugfs_file = debugfs_create_file(debugfs_name, 0444,
+							 pdrvdata.debugfs_dir,
+							 port,
+							 &port_debugfs_ops);
+	}
+	return 0;
+
+free_inbufs:
+	while ((buf = port->in_vq->vq_ops->detach_unused_buf(port->in_vq)))
+		free_buf(buf);
+free_device:
+	device_destroy(pdrvdata.class, port->dev->devt);
+free_cdev:
+	cdev_del(&port->cdev);
+free_port:
+	kfree(port);
+fail:
+	return err;
+}
+
+/*
+ * The workhandler for config-space updates.
  *
- * Finally we put our input buffer in the input queue, ready to receive. */
-static int __devinit virtcons_probe(struct virtio_device *dev)
+ * 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 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);
+		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) {
+		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 *callbacks[] = { hvc_handle_input, NULL};
-	const char *names[] = { "input", "output" };
-	struct virtqueue *vqs[2];
+	vq_callback_t **io_callbacks;
+	char **io_names;
+	struct virtqueue **vqs;
+	u32 i, j, nr_ports, nr_queues;
 	int err;
 
-	vdev = dev;
+	nr_ports = portdev->config.max_nr_ports;
+	nr_queues = use_multiport(portdev) ? (nr_ports + 1) * 2 : 2;
 
-	/* This is the scratch page we use to receive console input */
-	inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!inbuf) {
+	vqs = kmalloc(nr_queues * sizeof(struct virtqueue *), GFP_KERNEL);
+	if (!vqs) {
 		err = -ENOMEM;
 		goto fail;
 	}
+	io_callbacks = kmalloc(nr_queues * sizeof(vq_callback_t *), GFP_KERNEL);
+	if (!io_callbacks) {
+		err = -ENOMEM;
+		goto free_vqs;
+	}
+	io_names = kmalloc(nr_queues * sizeof(char *), GFP_KERNEL);
+	if (!io_names) {
+		err = -ENOMEM;
+		goto free_callbacks;
+	}
+	portdev->in_vqs = kmalloc(nr_ports * sizeof(struct virtqueue *),
+				  GFP_KERNEL);
+	if (!portdev->in_vqs) {
+		err = -ENOMEM;
+		goto free_names;
+	}
+	portdev->out_vqs = kmalloc(nr_ports * sizeof(struct virtqueue *),
+				   GFP_KERNEL);
+	if (!portdev->out_vqs) {
+		err = -ENOMEM;
+		goto free_invqs;
+	}
+
+	/*
+	 * For backward compat (newer host but older guest), the host
+	 * spawns a console port first and also inits the vqs for port
+	 * 0 before others.
+	 */
+	j = 0;
+	io_callbacks[j] = in_intr;
+	io_callbacks[j + 1] = NULL;
+	io_names[j] = "input";
+	io_names[j + 1] = "output";
+	j += 2;
 
+	if (use_multiport(portdev)) {
+		io_callbacks[j] = control_intr;
+		io_callbacks[j + 1] = NULL;
+		io_names[j] = "control-i";
+		io_names[j + 1] = "control-o";
+
+		for (i = 1; i < nr_ports; i++) {
+			j += 2;
+			io_callbacks[j] = in_intr;
+			io_callbacks[j + 1] = NULL;
+			io_names[j] = "input";
+			io_names[j + 1] = "output";
+		}
+	}
 	/* Find the queues. */
-	/* FIXME: This is why we want to wean off hvc: we do nothing
-	 * when input comes in. */
-	err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
+	err = portdev->vdev->config->find_vqs(portdev->vdev, nr_queues, vqs,
+					      io_callbacks,
+					      (const char **)io_names);
 	if (err)
+		goto free_outvqs;
+
+	j = 0;
+	portdev->in_vqs[0] = vqs[0];
+	portdev->out_vqs[0] = vqs[1];
+	j += 2;
+	if (use_multiport(portdev)) {
+		portdev->c_ivq = vqs[j];
+		portdev->c_ovq = vqs[j + 1];
+
+		for (i = 1; i < nr_ports; i++) {
+			j += 2;
+			portdev->in_vqs[i] = vqs[j];
+			portdev->out_vqs[i] = vqs[j + 1];
+		}
+	}
+	kfree(io_callbacks);
+	kfree(io_names);
+	kfree(vqs);
+
+	return 0;
+
+free_names:
+	kfree(io_names);
+free_callbacks:
+	kfree(io_callbacks);
+free_outvqs:
+	kfree(portdev->out_vqs);
+free_invqs:
+	kfree(portdev->in_vqs);
+free_vqs:
+	kfree(vqs);
+fail:
+	return err;
+}
+
+static const struct file_operations portdev_fops = {
+	.owner = THIS_MODULE,
+};
+
+/*
+ * Once we're further in boot, we get probed like any other virtio
+ * device.
+ *
+ * If the host also supports multiple console ports, we check the
+ * config space to see how many ports the host has spawned.  We
+ * initialize each port found.
+ */
+static int __devinit virtcons_probe(struct virtio_device *vdev)
+{
+	struct ports_device *portdev;
+	u32 i;
+	int err;
+	bool multiport;
+
+	portdev = kmalloc(sizeof(*portdev), GFP_KERNEL);
+	if (!portdev) {
+		err = -ENOMEM;
+		goto fail;
+	}
+
+	/* Attach this portdev to this virtio_device, and vice-versa. */
+	portdev->vdev = vdev;
+	vdev->priv = portdev;
+
+	spin_lock_irq(&pdrvdata_lock);
+	portdev->drv_index = pdrvdata.index++;
+	spin_unlock_irq(&pdrvdata_lock);
+
+	portdev->chr_major = register_chrdev(0, "virtio-portsdev",
+					     &portdev_fops);
+	if (portdev->chr_major < 0) {
+		dev_err(&vdev->dev,
+			"Error %d registering chrdev for device %u\n",
+			portdev->chr_major, portdev->drv_index);
+		err = portdev->chr_major;
 		goto free;
+	}
 
-	in_vq = vqs[0];
-	out_vq = vqs[1];
+	multiport = false;
+	portdev->config.nr_ports = 1;
+	portdev->config.max_nr_ports = 1;
+	if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
+		multiport = true;
+		vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT;
 
-	/* Start using the new console output. */
-	virtio_cons.get_chars = get_chars;
-	virtio_cons.put_chars = put_chars;
-	virtio_cons.notifier_add = notifier_add_vio;
-	virtio_cons.notifier_del = notifier_del_vio;
-	virtio_cons.notifier_hangup = notifier_del_vio;
-
-	/* The first argument of hvc_alloc() is the virtual console number, so
-	 * we use zero.  The second argument is the parameter for the
-	 * notification mechanism (like irq number). We currently leave this
-	 * as zero, virtqueues have implicit notifications.
-	 *
-	 * The third argument is a "struct hv_ops" containing the put_chars()
-	 * get_chars(), notifier_add() and notifier_del() pointers.
-	 * The final argument is the output buffer size: we can do any size,
-	 * so we put PAGE_SIZE here. */
-	hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE);
-	if (IS_ERR(hvc)) {
-		err = PTR_ERR(hvc);
-		goto free_vqs;
+		vdev->config->get(vdev, offsetof(struct virtio_console_config,
+						 nr_ports),
+				  &portdev->config.nr_ports,
+				  sizeof(portdev->config.nr_ports));
+		vdev->config->get(vdev, offsetof(struct virtio_console_config,
+						 max_nr_ports),
+				  &portdev->config.max_nr_ports,
+				  sizeof(portdev->config.max_nr_ports));
+		if (portdev->config.nr_ports > portdev->config.max_nr_ports) {
+			dev_warn(&vdev->dev,
+				 "More ports (%u) specified than allowed (%u). Will init %u ports.",
+				 portdev->config.nr_ports,
+				 portdev->config.max_nr_ports,
+				 portdev->config.max_nr_ports);
+
+			portdev->config.nr_ports = portdev->config.max_nr_ports;
+		}
+	}
+
+	/* Let the Host know we support multiple ports.*/
+	vdev->config->finalize_features(vdev);
+
+	err = init_vqs(portdev);
+	if (err < 0) {
+		dev_err(&vdev->dev, "Error %d initializing vqs\n", err);
+		goto free_chrdev;
+	}
+
+	spin_lock_init(&portdev->ports_lock);
+	INIT_LIST_HEAD(&portdev->ports);
+
+	if (multiport) {
+		spin_lock_init(&portdev->cvq_lock);
+		INIT_WORK(&portdev->control_work, &control_work_handler);
+		INIT_WORK(&portdev->config_work, &config_work_handler);
+
+		err = fill_queue(portdev->c_ivq, &portdev->cvq_lock);
+		if (!err) {
+			dev_err(&vdev->dev,
+				"Error allocating buffers for control queue\n");
+			err = -ENOMEM;
+			goto free_vqs;
+		}
 	}
 
-	/* Register the input buffer the first time. */
-	add_inbuf();
+	for (i = 0; i < portdev->config.nr_ports; i++)
+		add_port(portdev, i);
+
+	/* Start using the new console output. */
+	early_put_chars = NULL;
 	return 0;
 
 free_vqs:
 	vdev->config->del_vqs(vdev);
+	kfree(portdev->in_vqs);
+	kfree(portdev->out_vqs);
+free_chrdev:
+	unregister_chrdev(portdev->chr_major, "virtio-portsdev");
 free:
-	kfree(inbuf);
+	kfree(portdev);
 fail:
 	return err;
 }
 
+static void virtcons_remove(struct virtio_device *vdev)
+{
+	struct ports_device *portdev;
+	struct port *port, *port2;
+	struct port_buffer *buf;
+	unsigned int len;
+
+	portdev = vdev->priv;
+
+	cancel_work_sync(&portdev->control_work);
+	cancel_work_sync(&portdev->config_work);
+
+	list_for_each_entry_safe(port, port2, &portdev->ports, list)
+		remove_port(port);
+
+	unregister_chrdev(portdev->chr_major, "virtio-portsdev");
+
+	while ((buf = portdev->c_ivq->vq_ops->get_buf(portdev->c_ivq, &len)))
+		free_buf(buf);
+
+	while ((buf = portdev->c_ivq->vq_ops->detach_unused_buf(portdev->c_ivq)))
+		free_buf(buf);
+
+	vdev->config->del_vqs(vdev);
+	kfree(portdev->in_vqs);
+	kfree(portdev->out_vqs);
+
+	kfree(portdev);
+}
+
 static struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
 	{ 0 },
@@ -253,6 +1511,7 @@ static struct virtio_device_id id_table[] = {
 
 static unsigned int features[] = {
 	VIRTIO_CONSOLE_F_SIZE,
+	VIRTIO_CONSOLE_F_MULTIPORT,
 };
 
 static struct virtio_driver virtio_console = {
@@ -262,14 +1521,41 @@ static struct virtio_driver virtio_console = {
 	.driver.owner =	THIS_MODULE,
 	.id_table =	id_table,
 	.probe =	virtcons_probe,
-	.config_changed = virtcons_apply_config,
+	.remove =	virtcons_remove,
+	.config_changed = config_intr,
 };
 
 static int __init init(void)
 {
+	int err;
+
+	pdrvdata.class = class_create(THIS_MODULE, "virtio-ports");
+	if (IS_ERR(pdrvdata.class)) {
+		err = PTR_ERR(pdrvdata.class);
+		pr_err("Error %d creating virtio-ports class\n", err);
+		return err;
+	}
+
+	pdrvdata.debugfs_dir = debugfs_create_dir("virtio-ports", NULL);
+	if (!pdrvdata.debugfs_dir) {
+		pr_warning("Error %ld creating debugfs dir for virtio-ports\n",
+			   PTR_ERR(pdrvdata.debugfs_dir));
+	}
+	INIT_LIST_HEAD(&pdrvdata.consoles);
+
 	return register_virtio_driver(&virtio_console);
 }
+
+static void __exit fini(void)
+{
+	unregister_virtio_driver(&virtio_console);
+
+	class_destroy(pdrvdata.class);
+	if (pdrvdata.debugfs_dir)
+		debugfs_remove_recursive(pdrvdata.debugfs_dir);
+}
 module_init(init);
+module_exit(fini);
 
 MODULE_DEVICE_TABLE(virtio, id_table);
 MODULE_DESCRIPTION("Virtio console driver");
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 505be88c82a..369f2eebbad 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -28,7 +28,7 @@
 struct virtio_balloon
 {
 	struct virtio_device *vdev;
-	struct virtqueue *inflate_vq, *deflate_vq;
+	struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
 
 	/* Where the ballooning thread waits for config to change. */
 	wait_queue_head_t config_change;
@@ -49,6 +49,10 @@ struct virtio_balloon
 	/* The array of pfns we tell the Host about. */
 	unsigned int num_pfns;
 	u32 pfns[256];
+
+	/* Memory statistics */
+	int need_stats_update;
+	struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
 };
 
 static struct virtio_device_id id_table[] = {
@@ -154,6 +158,72 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num)
 	}
 }
 
+static inline void update_stat(struct virtio_balloon *vb, int idx,
+			       u16 tag, u64 val)
+{
+	BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
+	vb->stats[idx].tag = tag;
+	vb->stats[idx].val = val;
+}
+
+#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
+
+static void update_balloon_stats(struct virtio_balloon *vb)
+{
+	unsigned long events[NR_VM_EVENT_ITEMS];
+	struct sysinfo i;
+	int idx = 0;
+
+	all_vm_events(events);
+	si_meminfo(&i);
+
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
+				pages_to_bytes(events[PSWPIN]));
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
+				pages_to_bytes(events[PSWPOUT]));
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
+				pages_to_bytes(i.freeram));
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
+				pages_to_bytes(i.totalram));
+}
+
+/*
+ * While most virtqueues communicate guest-initiated requests to the hypervisor,
+ * the stats queue operates in reverse.  The driver initializes the virtqueue
+ * with a single buffer.  From that point forward, all conversations consist of
+ * a hypervisor request (a call to this function) which directs us to refill
+ * the virtqueue with a fresh stats buffer.  Since stats collection can sleep,
+ * we notify our kthread which does the actual work via stats_handle_request().
+ */
+static void stats_request(struct virtqueue *vq)
+{
+	struct virtio_balloon *vb;
+	unsigned int len;
+
+	vb = vq->vq_ops->get_buf(vq, &len);
+	if (!vb)
+		return;
+	vb->need_stats_update = 1;
+	wake_up(&vb->config_change);
+}
+
+static void stats_handle_request(struct virtio_balloon *vb)
+{
+	struct virtqueue *vq;
+	struct scatterlist sg;
+
+	vb->need_stats_update = 0;
+	update_balloon_stats(vb);
+
+	vq = vb->stats_vq;
+	sg_init_one(&sg, vb->stats, sizeof(vb->stats));
+	if (vq->vq_ops->add_buf(vq, &sg, 1, 0, vb) < 0)
+		BUG();
+	vq->vq_ops->kick(vq);
+}
+
 static void virtballoon_changed(struct virtio_device *vdev)
 {
 	struct virtio_balloon *vb = vdev->priv;
@@ -190,8 +260,11 @@ static int balloon(void *_vballoon)
 		try_to_freeze();
 		wait_event_interruptible(vb->config_change,
 					 (diff = towards_target(vb)) != 0
+					 || vb->need_stats_update
 					 || kthread_should_stop()
 					 || freezing(current));
+		if (vb->need_stats_update)
+			stats_handle_request(vb);
 		if (diff > 0)
 			fill_balloon(vb, diff);
 		else if (diff < 0)
@@ -204,10 +277,10 @@ static int balloon(void *_vballoon)
 static int virtballoon_probe(struct virtio_device *vdev)
 {
 	struct virtio_balloon *vb;
-	struct virtqueue *vqs[2];
-	vq_callback_t *callbacks[] = { balloon_ack, balloon_ack };
-	const char *names[] = { "inflate", "deflate" };
-	int err;
+	struct virtqueue *vqs[3];
+	vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
+	const char *names[] = { "inflate", "deflate", "stats" };
+	int err, nvqs;
 
 	vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
 	if (!vb) {
@@ -219,14 +292,31 @@ static int virtballoon_probe(struct virtio_device *vdev)
 	vb->num_pages = 0;
 	init_waitqueue_head(&vb->config_change);
 	vb->vdev = vdev;
+	vb->need_stats_update = 0;
 
-	/* We expect two virtqueues. */
-	err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
+	/* We expect two virtqueues: inflate and deflate,
+	 * and optionally stat. */
+	nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
+	err = vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names);
 	if (err)
 		goto out_free_vb;
 
 	vb->inflate_vq = vqs[0];
 	vb->deflate_vq = vqs[1];
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
+		struct scatterlist sg;
+		vb->stats_vq = vqs[2];
+
+		/*
+		 * Prime this virtqueue with one buffer so the hypervisor can
+		 * use it to signal us later.
+		 */
+		sg_init_one(&sg, vb->stats, sizeof vb->stats);
+		if (vb->stats_vq->vq_ops->add_buf(vb->stats_vq,
+						  &sg, 1, 0, vb) < 0)
+			BUG();
+		vb->stats_vq->vq_ops->kick(vb->stats_vq);
+	}
 
 	vb->thread = kthread_run(balloon, vb, "vballoon");
 	if (IS_ERR(vb->thread)) {
@@ -264,7 +354,10 @@ static void __devexit virtballoon_remove(struct virtio_device *vdev)
 	kfree(vb);
 }
 
-static unsigned int features[] = { VIRTIO_BALLOON_F_MUST_TELL_HOST };
+static unsigned int features[] = {
+	VIRTIO_BALLOON_F_MUST_TELL_HOST,
+	VIRTIO_BALLOON_F_STATS_VQ,
+};
 
 static struct virtio_driver virtio_balloon_driver = {
 	.feature_table = features,
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 28d9cf7cf72..1d5191fab62 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -702,7 +702,7 @@ static struct pci_driver virtio_pci_driver = {
 	.name		= "virtio-pci",
 	.id_table	= virtio_pci_id_table,
 	.probe		= virtio_pci_probe,
-	.remove		= virtio_pci_remove,
+	.remove		= __devexit_p(virtio_pci_remove),
 #ifdef CONFIG_PM
 	.suspend	= virtio_pci_suspend,
 	.resume		= virtio_pci_resume,
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index fbd2ecde93e..0db906b3c95 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -21,6 +21,24 @@
 #include <linux/virtio_config.h>
 #include <linux/device.h>
 
+/* virtio guest is communicating with a virtual "device" that actually runs on
+ * a host processor.  Memory barriers are used to control SMP effects. */
+#ifdef CONFIG_SMP
+/* Where possible, use SMP barriers which are more lightweight than mandatory
+ * barriers, because mandatory barriers control MMIO effects on accesses
+ * through relaxed memory I/O windows (which virtio does not use). */
+#define virtio_mb() smp_mb()
+#define virtio_rmb() smp_rmb()
+#define virtio_wmb() smp_wmb()
+#else
+/* We must force memory ordering even if guest is UP since host could be
+ * running on another CPU, but SMP barriers are defined to barrier() in that
+ * configuration. So fall back to mandatory barriers instead. */
+#define virtio_mb() mb()
+#define virtio_rmb() rmb()
+#define virtio_wmb() wmb()
+#endif
+
 #ifdef DEBUG
 /* For development, we want to crash whenever the ring is screwed. */
 #define BAD_RING(_vq, fmt, args...)				\
@@ -36,10 +54,9 @@
 			panic("%s:in_use = %i\n",		\
 			      (_vq)->vq.name, (_vq)->in_use);	\
 		(_vq)->in_use = __LINE__;			\
-		mb();						\
 	} while (0)
 #define END_USE(_vq) \
-	do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; mb(); } while(0)
+	do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0)
 #else
 #define BAD_RING(_vq, fmt, args...)				\
 	do {							\
@@ -221,13 +238,13 @@ static void vring_kick(struct virtqueue *_vq)
 	START_USE(vq);
 	/* Descriptors and available array need to be set before we expose the
 	 * new available array entries. */
-	wmb();
+	virtio_wmb();
 
 	vq->vring.avail->idx += vq->num_added;
 	vq->num_added = 0;
 
 	/* Need to update avail index before checking if we should notify */
-	mb();
+	virtio_mb();
 
 	if (!(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY))
 		/* Prod other side to tell it about changes. */
@@ -286,7 +303,7 @@ static void *vring_get_buf(struct virtqueue *_vq, unsigned int *len)
 	}
 
 	/* Only get used array entries after they have been exposed by host. */
-	rmb();
+	virtio_rmb();
 
 	i = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].id;
 	*len = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].len;
@@ -324,7 +341,7 @@ static bool vring_enable_cb(struct virtqueue *_vq)
 	/* We optimistically turn back on interrupts, then check if there was
 	 * more to do. */
 	vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT;
-	mb();
+	virtio_mb();
 	if (unlikely(more_used(vq))) {
 		END_USE(vq);
 		return false;
@@ -334,6 +351,30 @@ static bool vring_enable_cb(struct virtqueue *_vq)
 	return true;
 }
 
+static void *vring_detach_unused_buf(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	unsigned int i;
+	void *buf;
+
+	START_USE(vq);
+
+	for (i = 0; i < vq->vring.num; i++) {
+		if (!vq->data[i])
+			continue;
+		/* detach_buf clears data, so grab it now. */
+		buf = vq->data[i];
+		detach_buf(vq, i);
+		END_USE(vq);
+		return buf;
+	}
+	/* That should have freed everything. */
+	BUG_ON(vq->num_free != vq->vring.num);
+
+	END_USE(vq);
+	return NULL;
+}
+
 irqreturn_t vring_interrupt(int irq, void *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
@@ -360,6 +401,7 @@ static struct virtqueue_ops vring_vq_ops = {
 	.kick = vring_kick,
 	.disable_cb = vring_disable_cb,
 	.enable_cb = vring_enable_cb,
+	.detach_unused_buf = vring_detach_unused_buf,
 };
 
 struct virtqueue *vring_new_virtqueue(unsigned int num,
@@ -406,8 +448,11 @@ struct virtqueue *vring_new_virtqueue(unsigned int num,
 	/* Put everything in free lists. */
 	vq->num_free = num;
 	vq->free_head = 0;
-	for (i = 0; i < num-1; i++)
+	for (i = 0; i < num-1; i++) {
 		vq->vring.desc[i].next = i+1;
+		vq->data[i] = NULL;
+	}
+	vq->data[i] = NULL;
 
 	return &vq->vq;
 }