Merge branch 'quilt/rr'

Conflicts:
	drivers/char/hvc_console.c
	drivers/char/hvc_console.h

12 files changed, 716 insertions, 202 deletions

diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index a99d7031cdf9..45d5a217484f 100644
--- a/Documentation/cpu-hotplug.txt
+++ b/Documentation/cpu-hotplug.txt
@@ -2,7 +2,7 @@
 
 		Maintainers:
 		CPU Hotplug Core:
-			Rusty Russell <rusty@rustycorp.com.au>
+			Rusty Russell <rusty@rustcorp.com.au>
 			Srivatsa Vaddagiri <vatsa@in.ibm.com>
 		i386:
 			Zwane Mwaikambo <zwane@arm.linux.org.uk>
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 42208511b5c0..3119f5db75bd 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -34,7 +34,6 @@
 #include <sys/uio.h>
 #include <termios.h>
 #include <getopt.h>
-#include <zlib.h>
 #include <assert.h>
 #include <sched.h>
 #include <limits.h>
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index a035ae39a359..5096d92f5b89 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1,18 +1,5 @@
-/*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
  *
  * 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
@@ -30,45 +17,289 @@
  */
 #include <linux/err.h>
 #include <linux/init.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
 #include <linux/virtio.h>
 #include <linux/virtio_console.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 {
+	/*
+	 * 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;
+};
+
+/*
+ * This is a per-device struct that stores data common to all the
+ * ports for that device (vdev->priv).
+ */
+struct ports_device {
+	/* Array of per-port IO virtqueues */
+	struct virtqueue **in_vqs, **out_vqs;
+
+	struct virtio_device *vdev;
+};
+
+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 struct holds the per-port data */
+struct port {
+	/* 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;
+
+	/*
+	 * The entries in this struct will be valid if this port is
+	 * hooked up to an hvc console
+	 */
+	struct console cons;
+};
+
+/* 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_vq(struct ports_device *portdev,
+				    struct virtqueue *vq)
+{
+	struct port *port;
+	struct console *cons;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pdrvdata_lock, flags);
+	list_for_each_entry(cons, &pdrvdata.consoles, list) {
+		port = container_of(cons, struct port, cons);
+		if (port->in_vq == vq || port->out_vq == vq)
+			goto out;
+	}
+	port = NULL;
+out:
+	spin_unlock_irqrestore(&pdrvdata_lock, flags);
+	return port;
+}
+
+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;
+
+	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;
+
+	vq = port->in_vq;
+	buf = vq->vq_ops->get_buf(vq, &len);
+	if (buf) {
+		buf->len = len;
+		buf->offset = 0;
+	}
+	return buf;
+}
+
+/*
+ * Create a scatter-gather list representing our input buffer and put
+ * it in the queue.
+ *
+ * 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;
+}
 
-/* This is our input buffer, and how much data is left in it. */
-static unsigned int in_len;
-static char *in, *inbuf;
+static bool port_has_data(struct port *port)
+{
+	unsigned long flags;
+	bool ret;
 
-/* The operations for our console. */
-static struct hv_ops virtio_cons;
+	ret = false;
+	spin_lock_irqsave(&port->inbuf_lock, flags);
+	if (port->inbuf)
+		ret = true;
+	spin_unlock_irqrestore(&port->inbuf_lock, flags);
 
-/* The hvc device */
-static struct hvc_struct *hvc;
+	return ret;
+}
 
-/*D:310 The put_chars() callback is pretty straightforward.
+/*
+ * 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)
+{
+	struct port_buffer *buf;
+	unsigned long flags;
+
+	if (!out_count || !port_has_data(port))
+		return 0;
+
+	buf = port->inbuf;
+	if (out_count > buf->len - buf->offset)
+		out_count = buf->len - buf->offset;
+
+	memcpy(out_buf, buf->buf + buf->offset, out_count);
+
+	/* Return the number of bytes actually copied */
+	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->portdev->vdev->dev, "failed add_buf\n");
+
+		spin_unlock_irqrestore(&port->inbuf_lock, flags);
+	}
+	return out_count;
+}
+
+/*
+ * The put_chars() callback is pretty straightforward.
  *
- * 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). */
+ * 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)
 {
 	struct scatterlist sg[1];
+	struct port *port;
+	struct virtqueue *out_vq;
 	unsigned int len;
 
+	port = find_port_by_vtermno(vtermno);
+	if (!port)
+		return 0;
+
+	if (unlikely(early_put_chars))
+		return early_put_chars(vtermno, buf, count);
+
+	out_vq = port->out_vq;
 	/* This is a convenient routine to initialize a single-elem sg list */
 	sg_init_one(sg, buf, count);
 
-	/* 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) {
+	/* This shouldn't fail: if it does, we lose chars. */
+	if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, port) >= 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();
 	}
@@ -77,93 +308,60 @@ static int put_chars(u32 vtermno, const char *buf, int count)
 	return count;
 }
 
-/* Create a scatter-gather list representing our input buffer and put it in the
- * queue. */
-static void add_inbuf(void)
-{
-	struct scatterlist sg[1];
-	sg_init_one(sg, inbuf, PAGE_SIZE);
-
-	/* 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);
-}
-
-/*D:350 get_chars() is the callback from the hvc_console infrastructure when
- * an interrupt is received.
+/*
+ * 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. */
+ * We call out to fill_readbuf that gets us the required data from the
+ * buffers that are queued up.
+ */
 static int get_chars(u32 vtermno, char *buf, int count)
 {
-	/* If we don't have an input queue yet, we can't get input. */
-	BUG_ON(!in_vq);
+	struct port *port;
 
-	/* No buffer?  Try to get one. */
-	if (!in_len) {
-		in = in_vq->vq_ops->get_buf(in_vq, &in_len);
-		if (!in)
-			return 0;
-	}
+	port = find_port_by_vtermno(vtermno);
+	if (!port)
+		return 0;
 
-	/* You want more than we have to give?  Well, try wanting less! */
-	if (in_len < count)
-		count = in_len;
-
-	/* Copy across to their buffer and increment offset. */
-	memcpy(buf, in, count);
-	in += count;
-	in_len -= count;
-
-	/* Finished?  Re-register buffer so Host will use it again. */
-	if (in_len == 0)
-		add_inbuf();
+	/* If we don't have an input queue yet, we can't get input. */
+	BUG_ON(!port->in_vq);
 
-	return count;
+	return fill_readbuf(port, buf, count);
 }
-/*:*/
 
-/*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.
- *
- * 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))
-{
-	virtio_cons.put_chars = put_chars;
-	return hvc_instantiate(0, 0, &virtio_cons);
-}
-
-/*
- * virtio console configuration. This supports:
- * - console resize
- */
-static void virtcons_apply_config(struct virtio_device *dev)
+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
- */
+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)
 {
+	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;
 }
@@ -175,73 +373,241 @@ static void notifier_del_vio(struct hvc_struct *hp, int data)
 
 static void hvc_handle_input(struct virtqueue *vq)
 {
-	if (hvc_poll(hvc))
+	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);
+	port->inbuf = get_inbuf(port);
+	spin_unlock_irqrestore(&port->inbuf_lock, flags);
+
+	if (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.
+/* The operations for the console. */
+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.
  *
- * Finally we put our input buffer in the input queue, ready to receive. */
-static int __devinit virtcons_probe(struct virtio_device *dev)
+ * 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))
+{
+	early_put_chars = put_chars;
+	return hvc_instantiate(0, 0, &hv_ops);
+}
+
+int __devinit 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);
+		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);
+
+	return 0;
+}
+
+static int __devinit add_port(struct ports_device *portdev)
 {
-	vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
-	const char *names[] = { "input", "output" };
-	struct virtqueue *vqs[2];
+	struct port *port;
+	struct port_buffer *inbuf;
 	int err;
 
-	vdev = dev;
+	port = kmalloc(sizeof(*port), GFP_KERNEL);
+	if (!port) {
+		err = -ENOMEM;
+		goto fail;
+	}
+
+	port->portdev = portdev;
+
+	port->inbuf = NULL;
+
+	port->in_vq = portdev->in_vqs[0];
+	port->out_vq = portdev->out_vqs[0];
 
-	/* This is the scratch page we use to receive console input */
-	inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	spin_lock_init(&port->inbuf_lock);
+
+	inbuf = alloc_buf(PAGE_SIZE);
 	if (!inbuf) {
 		err = -ENOMEM;
+		goto free_port;
+	}
+
+	/* Register the input buffer the first time. */
+	add_inbuf(port->in_vq, inbuf);
+
+	err = init_port_console(port);
+	if (err)
+		goto free_inbuf;
+
+	return 0;
+
+free_inbuf:
+	free_buf(inbuf);
+free_port:
+	kfree(port);
+fail:
+	return err;
+}
+
+static int init_vqs(struct ports_device *portdev)
+{
+	vq_callback_t **io_callbacks;
+	char **io_names;
+	struct virtqueue **vqs;
+	u32 nr_ports, nr_queues;
+	int err;
+
+	/* We currently only have one port and two queues for that port */
+	nr_ports = 1;
+	nr_queues = 2;
+
+	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;
+	}
+
+	io_callbacks[0] = hvc_handle_input;
+	io_callbacks[1] = NULL;
+	io_names[0] = "input";
+	io_names[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;
+		goto free_outvqs;
 
-	in_vq = vqs[0];
-	out_vq = vqs[1];
+	portdev->in_vqs[0] = vqs[0];
+	portdev->out_vqs[0] = vqs[1];
 
-	/* 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;
+	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;
+}
+
+/*
+ * Once we're further in boot, we get probed like any other virtio
+ * device.
+ */
+static int __devinit virtcons_probe(struct virtio_device *vdev)
+{
+	struct ports_device *portdev;
+	int err;
+
+	portdev = kmalloc(sizeof(*portdev), GFP_KERNEL);
+	if (!portdev) {
+		err = -ENOMEM;
+		goto fail;
 	}
 
-	/* Register the input buffer the first time. */
-	add_inbuf();
+	/* Attach this portdev to this virtio_device, and vice-versa. */
+	portdev->vdev = vdev;
+	vdev->priv = portdev;
+
+	err = init_vqs(portdev);
+	if (err < 0) {
+		dev_err(&vdev->dev, "Error %d initializing vqs\n", err);
+		goto free;
+	}
+
+	/* We only have one port. */
+	err = add_port(portdev);
+	if (err)
+		goto free_vqs;
+
+	/* 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:
-	kfree(inbuf);
+	kfree(portdev);
 fail:
 	return err;
 }
@@ -267,6 +633,8 @@ static struct virtio_driver virtio_console = {
 
 static int __init init(void)
 {
+	INIT_LIST_HEAD(&pdrvdata.consoles);
+
 	return register_virtio_driver(&virtio_console);
 }
 module_init(init);
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 505be88c82ae..3db3d242c3ee 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) {
@@ -220,13 +293,29 @@ static int virtballoon_probe(struct virtio_device *vdev)
 	init_waitqueue_head(&vb->config_change);
 	vb->vdev = vdev;
 
-	/* 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 +353,10 @@ 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 28d9cf7cf72f..1d5191fab62e 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 71929ee00d69..782b7292a3d8 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;
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 557bdad320b6..f53e9b868c26 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -220,7 +220,7 @@ static inline enum zone_type gfp_zone(gfp_t flags)
 					 ((1 << ZONES_SHIFT) - 1);
 
 	if (__builtin_constant_p(bit))
-		MAYBE_BUILD_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
+		BUILD_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
 	else {
 #ifdef CONFIG_DEBUG_VM
 		BUG_ON((GFP_ZONE_BAD >> bit) & 1);
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 328bca609b9b..b632226ddc2f 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -702,38 +702,6 @@ static inline void ftrace_dump(void) { }
 struct sysinfo;
 extern int do_sysinfo(struct sysinfo *info);
 
-#endif /* __KERNEL__ */
-
-#ifndef __EXPORTED_HEADERS__
-#ifndef __KERNEL__
-#warning Attempt to use kernel headers from user space, see http://kernelnewbies.org/KernelHeaders
-#endif /* __KERNEL__ */
-#endif /* __EXPORTED_HEADERS__ */
-
-#define SI_LOAD_SHIFT	16
-struct sysinfo {
-	long uptime;			/* Seconds since boot */
-	unsigned long loads[3];		/* 1, 5, and 15 minute load averages */
-	unsigned long totalram;		/* Total usable main memory size */
-	unsigned long freeram;		/* Available memory size */
-	unsigned long sharedram;	/* Amount of shared memory */
-	unsigned long bufferram;	/* Memory used by buffers */
-	unsigned long totalswap;	/* Total swap space size */
-	unsigned long freeswap;		/* swap space still available */
-	unsigned short procs;		/* Number of current processes */
-	unsigned short pad;		/* explicit padding for m68k */
-	unsigned long totalhigh;	/* Total high memory size */
-	unsigned long freehigh;		/* Available high memory size */
-	unsigned int mem_unit;		/* Memory unit size in bytes */
-	char _f[20-2*sizeof(long)-sizeof(int)];	/* Padding: libc5 uses this.. */
-};
-
-/* Force a compilation error if condition is true */
-#define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_ZERO(condition))
-
-/* Force a compilation error if condition is constant and true */
-#define MAYBE_BUILD_BUG_ON(cond) ((void)sizeof(char[1 - 2 * !!(cond)]))
-
 /* Force a compilation error if a constant expression is not a power of 2 */
 #define BUILD_BUG_ON_NOT_POWER_OF_2(n)			\
 	BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
@@ -745,6 +713,32 @@ struct sysinfo {
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
 #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
 
+/**
+ * BUILD_BUG_ON - break compile if a condition is true.
+ * @cond: the condition which the compiler should know is false.
+ *
+ * If you have some code which relies on certain constants being equal, or
+ * other compile-time-evaluated condition, you should use BUILD_BUG_ON to
+ * detect if someone changes it.
+ *
+ * The implementation uses gcc's reluctance to create a negative array, but
+ * gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments
+ * to inline functions).  So as a fallback we use the optimizer; if it can't
+ * prove the condition is false, it will cause a link error on the undefined
+ * "__build_bug_on_failed".  This error message can be harder to track down
+ * though, hence the two different methods.
+ */
+#ifndef __OPTIMIZE__
+#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
+#else
+extern int __build_bug_on_failed;
+#define BUILD_BUG_ON(condition)					\
+	do {							\
+		((void)sizeof(char[1 - 2*!!(condition)]));	\
+		if (condition) __build_bug_on_failed = 1;	\
+	} while(0)
+#endif
+
 /* Trap pasters of __FUNCTION__ at compile-time */
 #define __FUNCTION__ (__func__)
 
@@ -760,4 +754,28 @@ struct sysinfo {
 # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 #endif
 
+#else /* __KERNEL__ */
+#ifndef __EXPORTED_HEADERS__
+#warning Attempt to use kernel headers from user space, see http://kernelnewbies.org/KernelHeaders
+#endif /* __EXPORTED_HEADERS__ */
+#endif /* !__KERNEL__ */
+
+#define SI_LOAD_SHIFT	16
+struct sysinfo {
+	long uptime;			/* Seconds since boot */
+	unsigned long loads[3];		/* 1, 5, and 15 minute load averages */
+	unsigned long totalram;		/* Total usable main memory size */
+	unsigned long freeram;		/* Available memory size */
+	unsigned long sharedram;	/* Amount of shared memory */
+	unsigned long bufferram;	/* Memory used by buffers */
+	unsigned long totalswap;	/* Total swap space size */
+	unsigned long freeswap;		/* swap space still available */
+	unsigned short procs;		/* Number of current processes */
+	unsigned short pad;		/* explicit padding for m68k */
+	unsigned long totalhigh;	/* Total high memory size */
+	unsigned long freehigh;		/* Available high memory size */
+	unsigned int mem_unit;		/* Memory unit size in bytes */
+	char _f[20-2*sizeof(long)-sizeof(int)];	/* Padding: libc5 uses this.. */
+};
+
 #endif
diff --git a/include/linux/kmemcheck.h b/include/linux/kmemcheck.h
index 08d7dc4ddf40..39f8453239f7 100644
--- a/include/linux/kmemcheck.h
+++ b/include/linux/kmemcheck.h
@@ -76,7 +76,7 @@ bool kmemcheck_is_obj_initialized(unsigned long addr, size_t size);
 									\
 		_n = (long) &((ptr)->name##_end)			\
 			- (long) &((ptr)->name##_begin);		\
-		MAYBE_BUILD_BUG_ON(_n < 0);				\
+		BUILD_BUG_ON(_n < 0);					\
 									\
 		kmemcheck_mark_initialized(&((ptr)->name##_begin), _n);	\
 	} while (0)
diff --git a/include/linux/virtio_balloon.h b/include/linux/virtio_balloon.h
index 1418f048cb34..a50ecd1b81a2 100644
--- a/include/linux/virtio_balloon.h
+++ b/include/linux/virtio_balloon.h
@@ -7,6 +7,7 @@
 
 /* The feature bitmap for virtio balloon */
 #define VIRTIO_BALLOON_F_MUST_TELL_HOST	0 /* Tell before reclaiming pages */
+#define VIRTIO_BALLOON_F_STATS_VQ	1 /* Memory Stats virtqueue */
 
 /* Size of a PFN in the balloon interface. */
 #define VIRTIO_BALLOON_PFN_SHIFT 12
@@ -18,4 +19,18 @@ struct virtio_balloon_config
 	/* Number of pages we've actually got in balloon. */
 	__le32 actual;
 };
+
+#define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
+#define VIRTIO_BALLOON_S_SWAP_OUT 1   /* Amount of memory swapped out */
+#define VIRTIO_BALLOON_S_MAJFLT   2   /* Number of major faults */
+#define VIRTIO_BALLOON_S_MINFLT   3   /* Number of minor faults */
+#define VIRTIO_BALLOON_S_MEMFREE  4   /* Total amount of free memory */
+#define VIRTIO_BALLOON_S_MEMTOT   5   /* Total amount of memory */
+#define VIRTIO_BALLOON_S_NR       6
+
+struct virtio_balloon_stat {
+	u16 tag;
+	u64 val;
+} __attribute__((packed));
+
 #endif /* _LINUX_VIRTIO_BALLOON_H */
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 0093dd7c1d6f..800617b4ddd5 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -109,7 +109,10 @@ static inline bool virtio_has_feature(const struct virtio_device *vdev,
 				      unsigned int fbit)
 {
 	/* Did you forget to fix assumptions on max features? */
-	MAYBE_BUILD_BUG_ON(fbit >= 32);
+	if (__builtin_constant_p(fbit))
+		BUILD_BUG_ON(fbit >= 32);
+	else
+		BUG_ON(fbit >= 32);
 
 	if (fbit < VIRTIO_TRANSPORT_F_START)
 		virtio_check_driver_offered_feature(vdev, fbit);
diff --git a/include/linux/virtio_console.h b/include/linux/virtio_console.h
index fe885174cc1f..9e0da40beae0 100644
--- a/include/linux/virtio_console.h
+++ b/include/linux/virtio_console.h
@@ -3,8 +3,10 @@
 #include <linux/types.h>
 #include <linux/virtio_ids.h>
 #include <linux/virtio_config.h>
-/* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
- * anyone can use the definitions to implement compatible drivers/servers. */
+/*
+ * This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
+ * anyone can use the definitions to implement compatible drivers/servers.
+ */
 
 /* Feature bits */
 #define VIRTIO_CONSOLE_F_SIZE	0	/* Does host provide console size? */