Multiple port support for virtio-console

Multiple port support for virtio-console

[Amit Shah]

Hello all,

Here is a new iteration of the patch series that implements a
transport for guest and host communications.

I've tested for compatibility (old qemu & new kernel, new qemu & old
kernel, new qemu & new kernel) and it all works fine*.

There are a few items on my todo list but this works well.

New since last send:
- live migration support**
- write path in the guest driver can now be called from irq context

TODO:
- Convert all config writes to little endian in qemu / convert from
little endian to host endian in guest
- Address a few FIXMEs spread in the code
- Introduce a watermark to stop a rogue host process flooding guest
with data

Conditions:
* Heavy IO on an hvc port and a non-hvc port causes memory corruption
  each time, same place. It could be realted to locking but I doubt
  that. This still has to be sorted out

** qemu now caches buffers till a char device is opened or till an
   entire write request is not received in userspace. These buffers
   aren't yet migrated.

Please review.
	Amit

[Qemu-devel] Multiple port support for virtio-console

[Amit Shah]

Hello all,

Here is a new iteration of the patch series that implements a
transport for guest and host communications.

I've tested for compatibility (old qemu & new kernel, new qemu & old
kernel, new qemu & new kernel) and it all works fine*.

There are a few items on my todo list but this works well.

New since last send:
- live migration support**
- write path in the guest driver can now be called from irq context

TODO:
- Convert all config writes to little endian in qemu / convert from
little endian to host endian in guest
- Address a few FIXMEs spread in the code
- Introduce a watermark to stop a rogue host process flooding guest
with data

Conditions:
* Heavy IO on an hvc port and a non-hvc port causes memory corruption
  each time, same place. It could be realted to locking but I doubt
  that. This still has to be sorted out

** qemu now caches buffers till a char device is opened or till an
   entire write request is not received in userspace. These buffers
   aren't yet migrated.

Please review.
	Amit

[PATCH 1/1] virtio_console: Add interface for guest and host communication

[Amit Shah]

Expose multiple char devices ("ports") for simple communication
between the host userspace and guest.

Sample offline usages can be: poking around in a guest to find out
the file systems used, applications installed, etc. Online usages
can be sharing of clipboard data between the guest and the host,
sending information about logged-in users to the host, locking the
screen or session when a vnc session is closed, and so on.

The interface presented to guest userspace is of a simple char
device, so it can be used like this:

    fd = open("/dev/vcon2", O_RDWR);
    ret = read(fd, buf, 100);
    ret = write(fd, string, strlen(string));

Each port is to be assigned a unique function, for example, the
first 4 ports may be reserved for libvirt usage, the next 4 for
generic streaming data and so on. This port-function mapping
isn't finalised yet.

For requirements, use-cases and some history see

    http://www.linux-kvm.org/page/VMchannel_Requirements

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 drivers/char/Kconfig           |    4 +-
 drivers/char/virtio_console.c  |  980 ++++++++++++++++++++++++++++++++++------
 include/linux/virtio_console.h |   34 ++
 3 files changed, 889 insertions(+), 129 deletions(-)

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index b8368e2..cbbb9a1 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -678,7 +678,9 @@ config VIRTIO_CONSOLE
 	select HVC_DRIVER
 	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/vconNN will
+	  be created when corresponding ports are found.
 
 config HVCS
 	tristate "IBM Hypervisor Virtual Console Server support"
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 0d328b5..edea6d3 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -13,6 +13,7 @@
  * 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) 2009, Amit Shah, 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
@@ -28,116 +29,395 @@
  * 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/device.h>
 #include <linux/err.h>
+#include <linux/fs.h>
 #include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/spinlock.h>
 #include <linux/virtio.h>
 #include <linux/virtio_ids.h>
 #include <linux/virtio_console.h>
+#include <linux/workqueue.h>
 #include "hvc_console.h"
 
-/*D:340 These represent our input and output console queues, and the virtio
+/*D:340 FIXME 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;
+struct virtio_console_struct {
+	struct work_struct rx_work;
+	struct work_struct tx_work;
+	struct work_struct config_work;
 
-/* This is our input buffer, and how much data is left in it. */
-static unsigned int in_len;
-static char *in, *inbuf;
+	struct list_head port_head;
+	struct list_head unused_read_head;
+	struct list_head unused_write_head;
 
-/* The operations for our console. */
-static struct hv_ops virtio_cons;
+	/* To protect the list of unused write buffers */
+	spinlock_t write_list_lock;
 
-/* The hvc device */
-static struct hvc_struct *hvc;
+	struct virtio_device *vdev;
+	struct class *class;
+	struct virtqueue *in_vq, *out_vq;
 
-/*D:310 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). */
-static int put_chars(u32 vtermno, const char *buf, int count)
+	struct virtio_console_config *config;
+};
+
+/* This struct holds individual buffers received for each port */
+struct virtio_console_port_buffer {
+	struct list_head next;
+
+	char *buf;
+
+	size_t len; /* length of the buffer */
+	size_t offset; /* offset in the buf from which to consume data */
+};
+
+struct virtio_console_port {
+	/* Next port in the list */
+	struct list_head next;
+
+	/* Buffer management */
+	struct list_head readbuf_head;
+	wait_queue_head_t waitqueue;
+
+	/* Each port associates with a separate char device */
+	struct cdev cdev;
+	struct device *dev;
+
+	/* The hvc device, if this port is associated with a console */
+	struct hvc_struct *hvc;
+
+	bool host_connected;  /* Is the host device open */
+};
+
+static struct virtio_console_struct virtconsole;
+
+static int major = 60; /* from the experimental range */
+
+static struct virtio_console_port *get_port_from_id(u32 id)
 {
-	struct scatterlist sg[1];
-	unsigned int len;
-
-	/* 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) {
-		/* 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();
+	struct virtio_console_port *port;
+
+	list_for_each_entry(port, &virtconsole.port_head, next) {
+		if (MINOR(port->dev->devt) == id)
+			return port;
 	}
+	return NULL;
+}
 
-	/* We're expected to return the amount of data we wrote: all of it. */
-	return count;
+static int get_id_from_port(struct virtio_console_port *port)
+{
+	return MINOR(port->dev->devt);
 }
 
-/* Create a scatter-gather list representing our input buffer and put it in the
- * queue. */
-static void add_inbuf(void)
+static bool is_console_port(struct virtio_console_port *port)
 {
-	struct scatterlist sg[1];
-	sg_init_one(sg, inbuf, PAGE_SIZE);
+	u32 port_nr = get_id_from_port(port);
 
-	/* 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);
+	if (port_nr == VIRTIO_CONSOLE_CONSOLE_PORT ||
+	    port_nr == VIRTIO_CONSOLE_CONSOLE2_PORT)
+		return true;
+	return false;
 }
 
-/*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 inline bool use_multiport(void)
 {
-	/* If we don't have an input queue yet, we can't get input. */
-	BUG_ON(!in_vq);
+	/* This condition can be true when put_chars is called from
+	 * early_init
+	 */
+	if (!virtconsole.vdev)
+		return 0;
+	return virtconsole.vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+}
+
+static inline bool is_internal(u32 flags)
+{
+	return flags & VIRTIO_CONSOLE_ID_INTERNAL;
+}
+
+static ssize_t fill_readbuf(struct virtio_console_port *port,
+			    char *out_buf, size_t out_count, bool to_user)
+{
+	struct virtio_console_port_buffer *buf, *buf2;
+	ssize_t out_offset, ret;
+
+	out_offset = 0;
+	list_for_each_entry_safe(buf, buf2, &port->readbuf_head, next) {
+		size_t copy_size;
+
+		copy_size = out_count;
+		if (copy_size > buf->len - buf->offset)
+			copy_size = buf->len - buf->offset;
+
+		if (to_user) {
+			ret = copy_to_user(out_buf + out_offset,
+					   buf->buf + buf->offset,
+					   copy_size);
+			/* FIXME: Deal with ret != 0 */
+		} else {
+			memcpy(out_buf + out_offset,
+			       buf->buf + buf->offset,
+			       copy_size);
+			ret = 0; /* Emulate copy_to_user behaviour */
+		}
+
+		/* Return the number of bytes actually copied */
+		ret = copy_size - ret;
+		buf->offset += ret;
+		out_offset += ret;
+		out_count -= ret;
+
+		if (buf->len - buf->offset == 0) {
+			list_del(&buf->next);
+			kfree(buf->buf);
+			kfree(buf);
+		}
+		if (!out_count)
+			break;
+	}
+	return out_offset;
+}
+
+static bool wait_is_over(struct virtio_console_port *port)
+{
+	return !list_empty(&port->readbuf_head) || !port->host_connected;
+}
 
-	/* No buffer?  Try to get one. */
-	if (!in_len) {
-		in = in_vq->vq_ops->get_buf(in_vq, &in_len);
-		if (!in)
+static ssize_t virtconsole_read(struct file *filp, char __user *ubuf,
+			       size_t count, loff_t *offp)
+{
+	struct virtio_console_port *port;
+	ssize_t ret;
+
+	port = filp->private_data;
+
+	if (list_empty(&port->readbuf_head)) {
+		/* 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 (list_empty(&port->readbuf_head) && !port->host_connected)
+		return 0;
+
+	return fill_readbuf(port, ubuf, count, true);
+}
+
+static ssize_t send_buf(struct virtio_console_port *port,
+			const char *in_buf, size_t in_count,
+			u32 flags, bool from_user)
+{
+	struct virtqueue *out_vq;
+	struct virtio_console_port_buffer *buf, *buf2;
+	struct scatterlist sg[1];
+	struct virtio_console_header header;
+	size_t in_offset, copy_size;
+	ssize_t ret;
+	unsigned int header_len;
+
+	if (!in_count)
+		return 0;
+
+	out_vq = virtconsole.out_vq;
+
+	/* We can't send internal messages to a host that won't understand it */
+	if (!use_multiport() && is_internal(flags))
+		return 0;
+	header_len = 0;
+	if (use_multiport()) {
+		header.id = get_id_from_port(port);
+		header.flags = flags;
+		header.size = in_count;
+		header_len = sizeof(header);
 	}
 
-	/* You want more than we have to give?  Well, try wanting less! */
-	if (in_len < count)
-		count = in_len;
+	in_offset = 0; /* offset in the user buffer */
+	while (in_count - in_offset) {
+		copy_size = min(in_count - in_offset + header_len, PAGE_SIZE);
+
+		spin_lock(&virtconsole.write_list_lock);
+		list_for_each_entry_safe(buf, buf2,
+					 &virtconsole.unused_write_head,
+					 next) {
+			list_del(&buf->next);
+			break;
+		}
+		spin_unlock(&virtconsole.write_list_lock);
+		if (!buf)
+			break;
+		if (header_len) {
+			memcpy(buf->buf, &header, header_len);
+			copy_size -= header_len;
+		}
+		if (from_user)
+			ret = copy_from_user(buf->buf + header_len,
+					     in_buf + in_offset, copy_size);
+		else {
+			/* Since we're not sure when the host will actually
+			 * consume the data and tell us about it, we have
+			 * to copy the data here in case the caller
+			 * frees the in_buf
+			 */
+			memcpy(buf->buf + header_len,
+			       in_buf + in_offset, copy_size);
+			ret = 0; /* Emulate copy_from_user */
+		}
+		buf->len = header_len + copy_size - ret;
+		sg_init_one(sg, buf->buf, buf->len);
+
+		ret = out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, buf);
+		if (ret < 0) {
+			/* FIXME: Put the buf back in the list */
+			break;
+		}
+
+		in_offset += buf->len - header_len;
+		/* Only send size with the first buffer.  This way
+		 * userspace can find out a continuous stream of data
+		 * belonging to one write request and consume it
+		 * appropriately
+		 */
+		header.size = 0;
+
+		/* No space left anyway */
+		if (!ret)
+			break;
+	}
+	/* Tell Host to go! */
+	out_vq->vq_ops->kick(out_vq);
 
-	/* Copy across to their buffer and increment offset. */
-	memcpy(buf, in, count);
-	in += count;
-	in_len -= count;
+	/* We're expected to return the amount of data we wrote */
+	return in_offset;
+}
+
+static ssize_t virtconsole_write(struct file *filp, const char __user *ubuf,
+				 size_t count, loff_t *offp)
+{
+	struct virtio_console_port *port;
 
-	/* Finished?  Re-register buffer so Host will use it again. */
-	if (in_len == 0)
-		add_inbuf();
+	port = filp->private_data;
 
-	return count;
+	return send_buf(port, ubuf, count, 0, true);
 }
-/*:*/
 
-/*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.
+static unsigned int virtconsole_poll(struct file *filp, poll_table *wait)
+{
+	struct virtio_console_port *port;
+	unsigned int ret;
+
+	port = filp->private_data;
+	poll_wait(filp, &port->waitqueue, wait);
+
+	ret = 0;
+	if (!list_empty(&port->readbuf_head))
+		ret |= POLLIN | POLLRDNORM;
+	if (!port->host_connected)
+		ret |= POLLHUP;
+
+	return ret;
+}
+
+static int virtconsole_release(struct inode *inode, struct file *filp)
+{
+	struct virtio_console_control cpkt;
+
+	/* Notify host of port being closed */
+	cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+	cpkt.value = 0;
+	send_buf(filp->private_data, (char *)&cpkt, sizeof(cpkt),
+		 VIRTIO_CONSOLE_ID_INTERNAL, false);
+	return 0;
+}
+
+static int virtconsole_open(struct inode *inode, struct file *filp)
+{
+	struct cdev *cdev = inode->i_cdev;
+	struct virtio_console_port *port;
+	struct virtio_console_control cpkt;
+
+	port = container_of(cdev, struct virtio_console_port, cdev);
+	filp->private_data = port;
+
+	/* Notify host of port being opened */
+	cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+	cpkt.value = 1;
+	send_buf(filp->private_data, (char *)&cpkt, sizeof(cpkt),
+		 VIRTIO_CONSOLE_ID_INTERNAL, false);
+
+	return 0;
+}
+
+static const struct file_operations virtconsole_fops = {
+	.owner = THIS_MODULE,
+	.open  = virtconsole_open,
+	.read  = virtconsole_read,
+	.write = virtconsole_write,
+	.poll  = virtconsole_poll,
+	.release = virtconsole_release,
+};
+
+/*D:310 The cons_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 cons_put_chars(u32 vtermno, const char *buf, int count)
 {
-	virtio_cons.put_chars = put_chars;
-	return hvc_instantiate(0, 0, &virtio_cons);
+	struct virtio_console_port *port;
+
+	port = get_port_from_id(vtermno);
+	if (!port)
+		return 0;
+
+	return send_buf(port, buf, count, 0, false);
 }
 
+/*D:350 cons_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 cons_get_chars(u32 vtermno, char *buf, int count)
+{
+	struct virtio_console_port *port;
+
+	/* If we don't have an input queue yet, we can't get input. */
+	BUG_ON(!virtconsole.in_vq);
+
+	port = get_port_from_id(vtermno);
+	if (!port)
+		return 0;
+
+	if (list_empty(&port->readbuf_head))
+		return 0;
+
+	return fill_readbuf(port, buf, count, false);
+
+}
+/*:*/
+
 /*
  * virtio console configuration. This supports:
  * - console resize
@@ -153,7 +433,11 @@ static void virtcons_apply_config(struct virtio_device *dev)
 		dev->config->get(dev,
 				 offsetof(struct virtio_console_config, rows),
 				 &ws.ws_row, sizeof(u16));
-		hvc_resize(hvc, ws);
+		/* We'll use this way of resizing only for legacy support
+		 * for newer userspace, use internal messages to indicate
+		 * console size changes so that it can be done per-port
+		 */
+		hvc_resize(get_port_from_id(VIRTIO_CONSOLE_CONSOLE_PORT)->hvc, ws);
 	}
 }
 
@@ -161,23 +445,363 @@ static void virtcons_apply_config(struct virtio_device *dev)
  * 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 int notifier_add_vio(struct hvc_struct *hp, int data)
+static int cons_notifier_add_vio(struct hvc_struct *hp, int data)
 {
 	hp->irq_requested = 1;
-	virtcons_apply_config(vdev);
+	virtcons_apply_config(virtconsole.vdev);
 
 	return 0;
 }
 
-static void notifier_del_vio(struct hvc_struct *hp, int data)
+static void cons_notifier_del_vio(struct hvc_struct *hp, int data)
 {
 	hp->irq_requested = 0;
 }
 
-static void hvc_handle_input(struct virtqueue *vq)
+/* The operations for our console. */
+static struct hv_ops virtio_cons = {
+	.get_chars = cons_get_chars,
+	.put_chars = cons_put_chars,
+	.notifier_add = cons_notifier_add_vio,
+	.notifier_del = cons_notifier_del_vio,
+	.notifier_hangup = cons_notifier_del_vio,
+};
+
+/*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);
+}
+
+static struct virtio_console_port_buffer *get_buf(size_t buf_size)
+{
+	struct virtio_console_port_buffer *buf;
+
+	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
+	if (!buf)
+		goto out;
+	buf->buf = kzalloc(buf_size, GFP_KERNEL);
+	if (!buf->buf) {
+		kfree(buf);
+		goto out;
+	}
+	buf->len = buf_size;
+out:
+	return buf;
+}
+
+static void fill_queue(struct virtqueue *vq, size_t buf_size,
+		       struct list_head *unused_head)
 {
-	if (hvc_poll(hvc))
+	struct scatterlist sg[1];
+	struct virtio_console_port_buffer *buf;
+	int ret;
+
+	do {
+		buf = get_buf(buf_size);
+		if (!buf)
+			break;
+		sg_init_one(sg, buf->buf, buf_size);
+
+		ret = vq->vq_ops->add_buf(vq, sg, 0, 1, buf);
+		if (ret < 0) {
+			kfree(buf->buf);
+			kfree(buf);
+			break;
+		}
+		/* We have to keep track of the unused buffers
+		 * so that they can be freed when the module
+		 * is being removed
+		 */
+		list_add_tail(&buf->next, unused_head);
+	} while (ret > 0);
+	vq->vq_ops->kick(vq);
+}
+
+static void fill_receive_queue(void)
+{
+	fill_queue(virtconsole.in_vq, PAGE_SIZE, &virtconsole.unused_read_head);
+}
+
+/* This function is only called from the init routine so the spinlock
+ * for the unused_write_head list isn't taken
+ */
+static void alloc_write_bufs(void)
+{
+	struct virtio_console_port_buffer *buf;
+	int i;
+
+	for (i = 0; i < 1024; i++) {
+		buf = get_buf(PAGE_SIZE);
+		if (!buf)
+			break;
+		list_add_tail(&buf->next, &virtconsole.unused_write_head);
+	}
+}
+
+static void handle_control_message(struct virtio_console_port *port,
+				   struct virtio_console_control *cpkt)
+{
+	switch (cpkt->event) {
+	case VIRTIO_CONSOLE_PORT_OPEN:
+		port->host_connected = cpkt->value;
+		break;
+	}
+}
+
+static void virtio_console_rx_work_handler(struct work_struct *work)
+{
+	struct virtio_console_port *port;
+	struct virtio_console_port_buffer *buf;
+	struct virtio_console_header header;
+	struct virtqueue *vq;
+	unsigned int tmplen, header_len;
+
+	header_len = use_multiport() ? sizeof(header) : 0;
+
+	port = NULL;
+	vq = virtconsole.in_vq;
+	while ((buf = vq->vq_ops->get_buf(vq, &tmplen))) {
+		/* The buffer is no longer unused */
+		list_del(&buf->next);
+
+		if (use_multiport()) {
+			memcpy(&header, buf->buf, header_len);
+			port = get_port_from_id(header.id);
+		} else
+			port = get_port_from_id(VIRTIO_CONSOLE_CONSOLE_PORT);
+		if (!port) {
+			/* No valid index at start of
+			 * buffer. Drop it.
+			 */
+			pr_debug("%s: invalid index in buffer, %c %d\n",
+				 __func__, buf->buf[0], buf->buf[0]);
+			kfree(buf->buf);
+			kfree(buf);
+			break;
+		}
+		if (use_multiport() && is_internal(header.flags)) {
+			handle_control_message(port,
+					       (struct virtio_console_control *)
+					       (buf->buf + header_len));
+
+			/* OPT: This buffer can be added to the
+			 * unused list to avoid free/alloc
+			 */
+			kfree(buf->buf);
+			kfree(buf);
+		} else {
+			buf->len = tmplen;
+			buf->offset = header_len;
+			list_add_tail(&buf->next, &port->readbuf_head);
+			/* We might have missed a connection
+			 * notification, e.g. before the queues were
+			 * initialised.
+			 */
+			port->host_connected = true;
+		}
+		wake_up_interruptible(&port->waitqueue);
+	}
+	/* hvc_poll takes a spinlock and calls hvc_push which calls
+	 * put_chars which results in a call to send_buf.
+	 *
+	 * It also calls get_chars with the spinlock held.
+	 */
+	if (port && is_console_port(port) && hvc_poll(port->hvc))
 		hvc_kick();
+
+	/* Allocate buffers for all the ones that got used up */
+	fill_receive_queue();
+}
+
+static void virtio_console_tx_work_handler(struct work_struct *work)
+{
+	struct virtqueue *vq;
+	struct virtio_console_port_buffer *buf;
+	unsigned int tmplen;
+
+	vq = virtconsole.out_vq;
+	while ((buf = vq->vq_ops->get_buf(vq, &tmplen))) {
+		/* 0 the buffer to not leak data from other processes */
+		memset(buf->buf, 0, buf->len);
+		spin_lock(&virtconsole.write_list_lock);
+		list_add_tail(&buf->next, &virtconsole.unused_write_head);
+		spin_unlock(&virtconsole.write_list_lock);
+	}
+}
+
+static void rx_intr(struct virtqueue *vq)
+{
+	schedule_work(&virtconsole.rx_work);
+}
+
+static void tx_intr(struct virtqueue *vq)
+{
+	schedule_work(&virtconsole.tx_work);
+}
+
+static void config_intr(struct virtio_device *vdev)
+{
+	/* Handle port hot-add */
+	schedule_work(&virtconsole.config_work);
+
+	/* Handle console size changes */
+	virtcons_apply_config(vdev);
+}
+
+static u32 virtconsole_get_hot_add_port(struct virtio_console_config *config)
+{
+	u32 i;
+	u32 port_nr;
+
+	for (i = 0; i < virtconsole.config->max_nr_ports / 32; i++) {
+		port_nr = ffs(config->ports_map[i] ^ virtconsole.config->ports_map[i]);
+		if (port_nr)
+			break;
+	}
+	if (unlikely(!port_nr))
+		return VIRTIO_CONSOLE_BAD_ID;
+
+	/* We used ffs above */
+	port_nr--;
+
+	/* FIXME: Do this only when add_port is successful */
+	virtconsole.config->ports_map[i] |= 1U << port_nr;
+
+	port_nr += i * 32;
+	return port_nr;
+}
+
+static u32 virtconsole_find_next_port(u32 *map, int *map_i)
+{
+	u32 port_nr;
+
+	while (1) {
+		port_nr = ffs(*map);
+		if (port_nr)
+			break;
+
+		if (unlikely(*map_i >= virtconsole.config->max_nr_ports / 32))
+			return VIRTIO_CONSOLE_BAD_ID;
+		++*map_i;
+		*map = virtconsole.config->ports_map[*map_i];
+	}
+	/* We used ffs above */
+	port_nr--;
+
+	/* FIXME: Do this only when add_port is successful / reset bit
+	 * in config space if add_port was unsuccessful
+	 */
+	*map &= ~(1U << port_nr);
+
+	port_nr += *map_i * 32;
+	return port_nr;
+}
+
+static int virtconsole_add_port(u32 port_nr)
+{
+	struct virtio_console_port *port;
+	dev_t devt;
+	int ret;
+
+	port = kzalloc(sizeof(*port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	devt = MKDEV(major, port_nr);
+	cdev_init(&port->cdev, &virtconsole_fops);
+
+	ret = register_chrdev_region(devt, 1, "virtio-console");
+	if (ret < 0) {
+		pr_err("%s: error registering chrdev region, ret = %d\n",
+		       __func__, ret);
+		goto free_cdev;
+	}
+	ret = cdev_add(&port->cdev, devt, 1);
+	if (ret < 0) {
+		pr_err("%s: error adding cdev, ret = %d\n", __func__, ret);
+		goto free_cdev;
+	}
+	port->dev = device_create(virtconsole.class, NULL, devt, NULL,
+				  "vcon%u", port_nr);
+	if (IS_ERR(port->dev)) {
+		ret = PTR_ERR(port->dev);
+		pr_err("%s: Error creating device, ret = %d\n", __func__, ret);
+		goto free_cdev;
+	}
+	INIT_LIST_HEAD(&port->readbuf_head);
+	init_waitqueue_head(&port->waitqueue);
+
+	list_add_tail(&port->next, &virtconsole.port_head);
+
+	if (is_console_port(port)) {
+		/* 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. */
+		port->hvc = hvc_alloc(port_nr, 0, &virtio_cons, PAGE_SIZE);
+		if (IS_ERR(port->hvc)) {
+			ret = PTR_ERR(port->hvc);
+			goto free_cdev;
+		}
+	}
+	pr_info("virtio-console port found at id %u\n", port_nr);
+
+	return 0;
+free_cdev:
+	unregister_chrdev(major, "virtio-console");
+	return ret;
+}
+
+static u32 get_ports_map_size(u32 max_ports)
+{
+	return sizeof(u32) * ((max_ports + 31) / 32);
+}
+
+static void virtio_console_config_work_handler(struct work_struct *work)
+{
+	struct virtio_console_config *virtconconf;
+	struct virtio_device *vdev = virtconsole.vdev;
+	u32 i, port_nr;
+	int ret;
+
+	virtconconf = kzalloc(sizeof(*virtconconf) +
+			      get_ports_map_size(virtconsole.config->max_nr_ports),
+			      GFP_KERNEL);
+	vdev->config->get(vdev,
+			  offsetof(struct virtio_console_config, nr_active_ports),
+			  &virtconconf->nr_active_ports,
+			  sizeof(virtconconf->nr_active_ports));
+	vdev->config->get(vdev,
+			  offsetof(struct virtio_console_config, ports_map),
+			  virtconconf->ports_map,
+			  get_ports_map_size(virtconsole.config->max_nr_ports));
+
+	/* Hot-add ports */
+	for (i = virtconsole.config->nr_active_ports;
+	     i < virtconconf->nr_active_ports; i++) {
+		port_nr = virtconsole_get_hot_add_port(virtconconf);
+		if (port_nr == VIRTIO_CONSOLE_BAD_ID)
+			continue;
+		ret = virtconsole_add_port(port_nr);
+		if (!ret)
+			virtconsole.config->nr_active_ports++;
+	}
+	kfree(virtconconf);
 }
 
 /*D:370 Once we're further in boot, we get probed like any other virtio device.
@@ -187,64 +811,143 @@ static void hvc_handle_input(struct virtqueue *vq)
  * never remove the console device we never need this pointer again.
  *
  * Finally we put our input buffer in the input queue, ready to receive. */
-static int __devinit virtcons_probe(struct virtio_device *dev)
+static int __devinit virtcons_probe(struct virtio_device *vdev)
 {
-	vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
+	vq_callback_t *callbacks[] = { rx_intr, tx_intr };
 	const char *names[] = { "input", "output" };
 	struct virtqueue *vqs[2];
-	int err;
-
-	vdev = dev;
-
-	/* This is the scratch page we use to receive console input */
-	inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!inbuf) {
-		err = -ENOMEM;
-		goto fail;
+	u32 i, map;
+	int ret, map_i;
+	u32 max_nr_ports;
+	bool multiport;
+
+	virtconsole.vdev = vdev;
+
+	multiport = false;
+	if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
+		multiport = true;
+		vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT;
+		vdev->config->finalize_features(vdev);
+
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_console_config,
+					   max_nr_ports),
+				  &max_nr_ports,
+				  sizeof(max_nr_ports));
+		virtconsole.config = kzalloc(sizeof(struct virtio_console_config)
+					     + get_ports_map_size(max_nr_ports),
+					     GFP_KERNEL);
+		if (!virtconsole.config)
+			return -ENOMEM;
+		virtconsole.config->max_nr_ports = max_nr_ports;
+
+		vdev->config->get(vdev, offsetof(struct virtio_console_config,
+						 nr_active_ports),
+				  &virtconsole.config->nr_active_ports,
+				  sizeof(virtconsole.config->nr_active_ports));
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_console_config,
+					   ports_map),
+				  virtconsole.config->ports_map,
+				  get_ports_map_size(max_nr_ports));
 	}
-
 	/* 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);
-	if (err)
-		goto free;
+	ret = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
+	if (ret)
+		goto fail;
 
-	in_vq = vqs[0];
-	out_vq = vqs[1];
+	virtconsole.in_vq = vqs[0];
+	virtconsole.out_vq = vqs[1];
+
+	INIT_LIST_HEAD(&virtconsole.port_head);
+	INIT_LIST_HEAD(&virtconsole.unused_read_head);
+	INIT_LIST_HEAD(&virtconsole.unused_write_head);
+
+	if (multiport) {
+		map_i = 0;
+		map = virtconsole.config->ports_map[map_i];
+		for (i = 0; i < virtconsole.config->nr_active_ports; i++) {
+			u32 port_nr;
+
+			port_nr = virtconsole_find_next_port(&map, &map_i);
+			if (unlikely(port_nr == VIRTIO_CONSOLE_BAD_ID))
+				continue;
+			virtconsole_add_port(port_nr);
+		}
+	} else
+		virtconsole_add_port(VIRTIO_CONSOLE_CONSOLE_PORT);
+
+	INIT_WORK(&virtconsole.rx_work, &virtio_console_rx_work_handler);
+	INIT_WORK(&virtconsole.tx_work, &virtio_console_tx_work_handler);
+	INIT_WORK(&virtconsole.config_work, &virtio_console_config_work_handler);
+	spin_lock_init(&virtconsole.write_list_lock);
+
+	fill_receive_queue();
+	alloc_write_bufs();
+	return 0;
 
-	/* 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;
+fail:
+	return ret;
+}
+
+static void virtcons_remove_port_data(struct virtio_console_port *port)
+{
+	struct virtio_console_port_buffer *buf, *buf2;
+
+#if 0 /* hvc_console is compiled in, at least on Fedora. */
+	if (is_console_port(port))
+		hvc_remove(hvc);
+#endif
+	device_destroy(virtconsole.class, port->dev->devt);
+	unregister_chrdev_region(port->dev->devt, 1);
+	cdev_del(&port->cdev);
+
+	/* Remove the buffers in which we have unconsumed data */
+	list_for_each_entry_safe(buf, buf2, &port->readbuf_head, next) {
+		list_del(&buf->next);
+		kfree(buf->buf);
+		kfree(buf);
 	}
+}
 
-	/* Register the input buffer the first time. */
-	add_inbuf();
-	return 0;
+static void virtcons_remove(struct virtio_device *vdev)
+{
+	struct virtio_console_port *port, *port2;
+	struct virtio_console_port_buffer *buf, *buf2;
+	char *tmpbuf;
+	int len;
+
+	unregister_chrdev(major, "virtio-console");
+	class_destroy(virtconsole.class);
+
+	cancel_work_sync(&virtconsole.rx_work);
+
+	/* Free up the buffers in the 'received' queue */
+	while ((tmpbuf = virtconsole.in_vq->vq_ops->get_buf(virtconsole.in_vq,
+							    &len)))
+		kfree(tmpbuf);
 
-free_vqs:
 	vdev->config->del_vqs(vdev);
-free:
-	kfree(inbuf);
-fail:
-	return err;
+
+	/* Free up the buffers that were unused */
+	list_for_each_entry_safe(buf, buf2, &virtconsole.unused_read_head, next) {
+		list_del(&buf->next);
+		kfree(buf->buf);
+		kfree(buf);
+	}
+	list_for_each_entry_safe(buf, buf2, &virtconsole.unused_write_head, next) {
+		list_del(&buf->next);
+		kfree(buf->buf);
+		kfree(buf);
+	}
+	list_for_each_entry_safe(port, port2, &virtconsole.port_head, next) {
+		list_del(&port->next);
+		virtcons_remove_port_data(port);
+		kfree(port);
+	}
+	kfree(virtconsole.config);
 }
 
 static struct virtio_device_id id_table[] = {
@@ -254,6 +957,7 @@ 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 = {
@@ -263,14 +967,34 @@ 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)
 {
-	return register_virtio_driver(&virtio_console);
+	int ret;
+
+	virtconsole.class = class_create(THIS_MODULE, "virtio-console");
+	if (IS_ERR(virtconsole.class)) {
+		pr_err("Error creating virtio-console class\n");
+		ret = PTR_ERR(virtconsole.class);
+		return ret;
+	}
+	ret = register_virtio_driver(&virtio_console);
+	if (ret) {
+		class_destroy(virtconsole.class);
+		return ret;
+	}
+	return 0;
+}
+
+static void __exit fini(void)
+{
+	unregister_virtio_driver(&virtio_console);
 }
 module_init(init);
+module_exit(fini);
 
 MODULE_DEVICE_TABLE(virtio, id_table);
 MODULE_DESCRIPTION("Virtio console driver");
diff --git a/include/linux/virtio_console.h b/include/linux/virtio_console.h
index b5f5198..9a3a3b9 100644
--- a/include/linux/virtio_console.h
+++ b/include/linux/virtio_console.h
@@ -7,14 +7,48 @@
 
 /* Feature bits */
 #define VIRTIO_CONSOLE_F_SIZE	0	/* Does host provide console size? */
+#define VIRTIO_CONSOLE_F_MULTIPORT 1	/* Does host provide multiple ports? */
+
+#define VIRTIO_CONSOLE_BAD_ID	(~(u32)0) /* Invalid port number */
+
+/* Port at which the virtio console is spawned */
+#define VIRTIO_CONSOLE_CONSOLE_PORT	0
+#define VIRTIO_CONSOLE_CONSOLE2_PORT	1
 
 struct virtio_console_config {
 	/* colums of the screens */
 	__u16 cols;
 	/* rows of the screens */
 	__u16 rows;
+	/* max. number of ports supported for each PCI device */
+	__u32 max_nr_ports;
+	/* number of ports in use */
+	__u32 nr_active_ports;
+	/* locations of the ports in use */
+	__u32 ports_map[0 /* (max_nr_ports + 31) / 32 */];
+} __attribute__((packed));
+
+struct virtio_console_control {
+	__u16 event;
+	__u16 value;
+};
+
+/* This struct is put in each buffer that gets passed to userspace and
+ * vice-versa
+ */
+struct virtio_console_header {
+	u32 id; /* Port number */
+	u32 flags; /* Some message between host and guest */
+	u32 size; /* Complete size of the write request - only sent
+		   * with the first buffer for each write request
+		   */
 } __attribute__((packed));
 
+/* Messages between host and guest */
+#define VIRTIO_CONSOLE_ID_INTERNAL	(1 << 0)
+
+/* Some events for internal messages */
+#define VIRTIO_CONSOLE_PORT_OPEN	0
 
 #ifdef __KERNEL__
 int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int));
-- 
1.6.2.5

[Qemu-devel] [PATCH 1/1] virtio_console: Add interface for guest and host communication

[Amit Shah]

Expose multiple char devices ("ports") for simple communication
between the host userspace and guest.

Sample offline usages can be: poking around in a guest to find out
the file systems used, applications installed, etc. Online usages
can be sharing of clipboard data between the guest and the host,
sending information about logged-in users to the host, locking the
screen or session when a vnc session is closed, and so on.

The interface presented to guest userspace is of a simple char
device, so it can be used like this:

    fd = open("/dev/vcon2", O_RDWR);
    ret = read(fd, buf, 100);
    ret = write(fd, string, strlen(string));

Each port is to be assigned a unique function, for example, the
first 4 ports may be reserved for libvirt usage, the next 4 for
generic streaming data and so on. This port-function mapping
isn't finalised yet.

For requirements, use-cases and some history see

    http://www.linux-kvm.org/page/VMchannel_Requirements

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 drivers/char/Kconfig           |    4 +-
 drivers/char/virtio_console.c  |  980 ++++++++++++++++++++++++++++++++++------
 include/linux/virtio_console.h |   34 ++
 3 files changed, 889 insertions(+), 129 deletions(-)

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index b8368e2..cbbb9a1 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -678,7 +678,9 @@ config VIRTIO_CONSOLE
 	select HVC_DRIVER
 	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/vconNN will
+	  be created when corresponding ports are found.
 
 config HVCS
 	tristate "IBM Hypervisor Virtual Console Server support"
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 0d328b5..edea6d3 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -13,6 +13,7 @@
  * 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) 2009, Amit Shah, 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
@@ -28,116 +29,395 @@
  * 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/device.h>
 #include <linux/err.h>
+#include <linux/fs.h>
 #include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/spinlock.h>
 #include <linux/virtio.h>
 #include <linux/virtio_ids.h>
 #include <linux/virtio_console.h>
+#include <linux/workqueue.h>
 #include "hvc_console.h"
 
-/*D:340 These represent our input and output console queues, and the virtio
+/*D:340 FIXME 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;
+struct virtio_console_struct {
+	struct work_struct rx_work;
+	struct work_struct tx_work;
+	struct work_struct config_work;
 
-/* This is our input buffer, and how much data is left in it. */
-static unsigned int in_len;
-static char *in, *inbuf;
+	struct list_head port_head;
+	struct list_head unused_read_head;
+	struct list_head unused_write_head;
 
-/* The operations for our console. */
-static struct hv_ops virtio_cons;
+	/* To protect the list of unused write buffers */
+	spinlock_t write_list_lock;
 
-/* The hvc device */
-static struct hvc_struct *hvc;
+	struct virtio_device *vdev;
+	struct class *class;
+	struct virtqueue *in_vq, *out_vq;
 
-/*D:310 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). */
-static int put_chars(u32 vtermno, const char *buf, int count)
+	struct virtio_console_config *config;
+};
+
+/* This struct holds individual buffers received for each port */
+struct virtio_console_port_buffer {
+	struct list_head next;
+
+	char *buf;
+
+	size_t len; /* length of the buffer */
+	size_t offset; /* offset in the buf from which to consume data */
+};
+
+struct virtio_console_port {
+	/* Next port in the list */
+	struct list_head next;
+
+	/* Buffer management */
+	struct list_head readbuf_head;
+	wait_queue_head_t waitqueue;
+
+	/* Each port associates with a separate char device */
+	struct cdev cdev;
+	struct device *dev;
+
+	/* The hvc device, if this port is associated with a console */
+	struct hvc_struct *hvc;
+
+	bool host_connected;  /* Is the host device open */
+};
+
+static struct virtio_console_struct virtconsole;
+
+static int major = 60; /* from the experimental range */
+
+static struct virtio_console_port *get_port_from_id(u32 id)
 {
-	struct scatterlist sg[1];
-	unsigned int len;
-
-	/* 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) {
-		/* 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();
+	struct virtio_console_port *port;
+
+	list_for_each_entry(port, &virtconsole.port_head, next) {
+		if (MINOR(port->dev->devt) == id)
+			return port;
 	}
+	return NULL;
+}
 
-	/* We're expected to return the amount of data we wrote: all of it. */
-	return count;
+static int get_id_from_port(struct virtio_console_port *port)
+{
+	return MINOR(port->dev->devt);
 }
 
-/* Create a scatter-gather list representing our input buffer and put it in the
- * queue. */
-static void add_inbuf(void)
+static bool is_console_port(struct virtio_console_port *port)
 {
-	struct scatterlist sg[1];
-	sg_init_one(sg, inbuf, PAGE_SIZE);
+	u32 port_nr = get_id_from_port(port);
 
-	/* 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);
+	if (port_nr == VIRTIO_CONSOLE_CONSOLE_PORT ||
+	    port_nr == VIRTIO_CONSOLE_CONSOLE2_PORT)
+		return true;
+	return false;
 }
 
-/*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 inline bool use_multiport(void)
 {
-	/* If we don't have an input queue yet, we can't get input. */
-	BUG_ON(!in_vq);
+	/* This condition can be true when put_chars is called from
+	 * early_init
+	 */
+	if (!virtconsole.vdev)
+		return 0;
+	return virtconsole.vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+}
+
+static inline bool is_internal(u32 flags)
+{
+	return flags & VIRTIO_CONSOLE_ID_INTERNAL;
+}
+
+static ssize_t fill_readbuf(struct virtio_console_port *port,
+			    char *out_buf, size_t out_count, bool to_user)
+{
+	struct virtio_console_port_buffer *buf, *buf2;
+	ssize_t out_offset, ret;
+
+	out_offset = 0;
+	list_for_each_entry_safe(buf, buf2, &port->readbuf_head, next) {
+		size_t copy_size;
+
+		copy_size = out_count;
+		if (copy_size > buf->len - buf->offset)
+			copy_size = buf->len - buf->offset;
+
+		if (to_user) {
+			ret = copy_to_user(out_buf + out_offset,
+					   buf->buf + buf->offset,
+					   copy_size);
+			/* FIXME: Deal with ret != 0 */
+		} else {
+			memcpy(out_buf + out_offset,
+			       buf->buf + buf->offset,
+			       copy_size);
+			ret = 0; /* Emulate copy_to_user behaviour */
+		}
+
+		/* Return the number of bytes actually copied */
+		ret = copy_size - ret;
+		buf->offset += ret;
+		out_offset += ret;
+		out_count -= ret;
+
+		if (buf->len - buf->offset == 0) {
+			list_del(&buf->next);
+			kfree(buf->buf);
+			kfree(buf);
+		}
+		if (!out_count)
+			break;
+	}
+	return out_offset;
+}
+
+static bool wait_is_over(struct virtio_console_port *port)
+{
+	return !list_empty(&port->readbuf_head) || !port->host_connected;
+}
 
-	/* No buffer?  Try to get one. */
-	if (!in_len) {
-		in = in_vq->vq_ops->get_buf(in_vq, &in_len);
-		if (!in)
+static ssize_t virtconsole_read(struct file *filp, char __user *ubuf,
+			       size_t count, loff_t *offp)
+{
+	struct virtio_console_port *port;
+	ssize_t ret;
+
+	port = filp->private_data;
+
+	if (list_empty(&port->readbuf_head)) {
+		/* 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 (list_empty(&port->readbuf_head) && !port->host_connected)
+		return 0;
+
+	return fill_readbuf(port, ubuf, count, true);
+}
+
+static ssize_t send_buf(struct virtio_console_port *port,
+			const char *in_buf, size_t in_count,
+			u32 flags, bool from_user)
+{
+	struct virtqueue *out_vq;
+	struct virtio_console_port_buffer *buf, *buf2;
+	struct scatterlist sg[1];
+	struct virtio_console_header header;
+	size_t in_offset, copy_size;
+	ssize_t ret;
+	unsigned int header_len;
+
+	if (!in_count)
+		return 0;
+
+	out_vq = virtconsole.out_vq;
+
+	/* We can't send internal messages to a host that won't understand it */
+	if (!use_multiport() && is_internal(flags))
+		return 0;
+	header_len = 0;
+	if (use_multiport()) {
+		header.id = get_id_from_port(port);
+		header.flags = flags;
+		header.size = in_count;
+		header_len = sizeof(header);
 	}
 
-	/* You want more than we have to give?  Well, try wanting less! */
-	if (in_len < count)
-		count = in_len;
+	in_offset = 0; /* offset in the user buffer */
+	while (in_count - in_offset) {
+		copy_size = min(in_count - in_offset + header_len, PAGE_SIZE);
+
+		spin_lock(&virtconsole.write_list_lock);
+		list_for_each_entry_safe(buf, buf2,
+					 &virtconsole.unused_write_head,
+					 next) {
+			list_del(&buf->next);
+			break;
+		}
+		spin_unlock(&virtconsole.write_list_lock);
+		if (!buf)
+			break;
+		if (header_len) {
+			memcpy(buf->buf, &header, header_len);
+			copy_size -= header_len;
+		}
+		if (from_user)
+			ret = copy_from_user(buf->buf + header_len,
+					     in_buf + in_offset, copy_size);
+		else {
+			/* Since we're not sure when the host will actually
+			 * consume the data and tell us about it, we have
+			 * to copy the data here in case the caller
+			 * frees the in_buf
+			 */
+			memcpy(buf->buf + header_len,
+			       in_buf + in_offset, copy_size);
+			ret = 0; /* Emulate copy_from_user */
+		}
+		buf->len = header_len + copy_size - ret;
+		sg_init_one(sg, buf->buf, buf->len);
+
+		ret = out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, buf);
+		if (ret < 0) {
+			/* FIXME: Put the buf back in the list */
+			break;
+		}
+
+		in_offset += buf->len - header_len;
+		/* Only send size with the first buffer.  This way
+		 * userspace can find out a continuous stream of data
+		 * belonging to one write request and consume it
+		 * appropriately
+		 */
+		header.size = 0;
+
+		/* No space left anyway */
+		if (!ret)
+			break;
+	}
+	/* Tell Host to go! */
+	out_vq->vq_ops->kick(out_vq);
 
-	/* Copy across to their buffer and increment offset. */
-	memcpy(buf, in, count);
-	in += count;
-	in_len -= count;
+	/* We're expected to return the amount of data we wrote */
+	return in_offset;
+}
+
+static ssize_t virtconsole_write(struct file *filp, const char __user *ubuf,
+				 size_t count, loff_t *offp)
+{
+	struct virtio_console_port *port;
 
-	/* Finished?  Re-register buffer so Host will use it again. */
-	if (in_len == 0)
-		add_inbuf();
+	port = filp->private_data;
 
-	return count;
+	return send_buf(port, ubuf, count, 0, true);
 }
-/*:*/
 
-/*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.
+static unsigned int virtconsole_poll(struct file *filp, poll_table *wait)
+{
+	struct virtio_console_port *port;
+	unsigned int ret;
+
+	port = filp->private_data;
+	poll_wait(filp, &port->waitqueue, wait);
+
+	ret = 0;
+	if (!list_empty(&port->readbuf_head))
+		ret |= POLLIN | POLLRDNORM;
+	if (!port->host_connected)
+		ret |= POLLHUP;
+
+	return ret;
+}
+
+static int virtconsole_release(struct inode *inode, struct file *filp)
+{
+	struct virtio_console_control cpkt;
+
+	/* Notify host of port being closed */
+	cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+	cpkt.value = 0;
+	send_buf(filp->private_data, (char *)&cpkt, sizeof(cpkt),
+		 VIRTIO_CONSOLE_ID_INTERNAL, false);
+	return 0;
+}
+
+static int virtconsole_open(struct inode *inode, struct file *filp)
+{
+	struct cdev *cdev = inode->i_cdev;
+	struct virtio_console_port *port;
+	struct virtio_console_control cpkt;
+
+	port = container_of(cdev, struct virtio_console_port, cdev);
+	filp->private_data = port;
+
+	/* Notify host of port being opened */
+	cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+	cpkt.value = 1;
+	send_buf(filp->private_data, (char *)&cpkt, sizeof(cpkt),
+		 VIRTIO_CONSOLE_ID_INTERNAL, false);
+
+	return 0;
+}
+
+static const struct file_operations virtconsole_fops = {
+	.owner = THIS_MODULE,
+	.open  = virtconsole_open,
+	.read  = virtconsole_read,
+	.write = virtconsole_write,
+	.poll  = virtconsole_poll,
+	.release = virtconsole_release,
+};
+
+/*D:310 The cons_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 cons_put_chars(u32 vtermno, const char *buf, int count)
 {
-	virtio_cons.put_chars = put_chars;
-	return hvc_instantiate(0, 0, &virtio_cons);
+	struct virtio_console_port *port;
+
+	port = get_port_from_id(vtermno);
+	if (!port)
+		return 0;
+
+	return send_buf(port, buf, count, 0, false);
 }
 
+/*D:350 cons_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 cons_get_chars(u32 vtermno, char *buf, int count)
+{
+	struct virtio_console_port *port;
+
+	/* If we don't have an input queue yet, we can't get input. */
+	BUG_ON(!virtconsole.in_vq);
+
+	port = get_port_from_id(vtermno);
+	if (!port)
+		return 0;
+
+	if (list_empty(&port->readbuf_head))
+		return 0;
+
+	return fill_readbuf(port, buf, count, false);
+
+}
+/*:*/
+
 /*
  * virtio console configuration. This supports:
  * - console resize
@@ -153,7 +433,11 @@ static void virtcons_apply_config(struct virtio_device *dev)
 		dev->config->get(dev,
 				 offsetof(struct virtio_console_config, rows),
 				 &ws.ws_row, sizeof(u16));
-		hvc_resize(hvc, ws);
+		/* We'll use this way of resizing only for legacy support
+		 * for newer userspace, use internal messages to indicate
+		 * console size changes so that it can be done per-port
+		 */
+		hvc_resize(get_port_from_id(VIRTIO_CONSOLE_CONSOLE_PORT)->hvc, ws);
 	}
 }
 
@@ -161,23 +445,363 @@ static void virtcons_apply_config(struct virtio_device *dev)
  * 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 int notifier_add_vio(struct hvc_struct *hp, int data)
+static int cons_notifier_add_vio(struct hvc_struct *hp, int data)
 {
 	hp->irq_requested = 1;
-	virtcons_apply_config(vdev);
+	virtcons_apply_config(virtconsole.vdev);
 
 	return 0;
 }
 
-static void notifier_del_vio(struct hvc_struct *hp, int data)
+static void cons_notifier_del_vio(struct hvc_struct *hp, int data)
 {
 	hp->irq_requested = 0;
 }
 
-static void hvc_handle_input(struct virtqueue *vq)
+/* The operations for our console. */
+static struct hv_ops virtio_cons = {
+	.get_chars = cons_get_chars,
+	.put_chars = cons_put_chars,
+	.notifier_add = cons_notifier_add_vio,
+	.notifier_del = cons_notifier_del_vio,
+	.notifier_hangup = cons_notifier_del_vio,
+};
+
+/*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);
+}
+
+static struct virtio_console_port_buffer *get_buf(size_t buf_size)
+{
+	struct virtio_console_port_buffer *buf;
+
+	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
+	if (!buf)
+		goto out;
+	buf->buf = kzalloc(buf_size, GFP_KERNEL);
+	if (!buf->buf) {
+		kfree(buf);
+		goto out;
+	}
+	buf->len = buf_size;
+out:
+	return buf;
+}
+
+static void fill_queue(struct virtqueue *vq, size_t buf_size,
+		       struct list_head *unused_head)
 {
-	if (hvc_poll(hvc))
+	struct scatterlist sg[1];
+	struct virtio_console_port_buffer *buf;
+	int ret;
+
+	do {
+		buf = get_buf(buf_size);
+		if (!buf)
+			break;
+		sg_init_one(sg, buf->buf, buf_size);
+
+		ret = vq->vq_ops->add_buf(vq, sg, 0, 1, buf);
+		if (ret < 0) {
+			kfree(buf->buf);
+			kfree(buf);
+			break;
+		}
+		/* We have to keep track of the unused buffers
+		 * so that they can be freed when the module
+		 * is being removed
+		 */
+		list_add_tail(&buf->next, unused_head);
+	} while (ret > 0);
+	vq->vq_ops->kick(vq);
+}
+
+static void fill_receive_queue(void)
+{
+	fill_queue(virtconsole.in_vq, PAGE_SIZE, &virtconsole.unused_read_head);
+}
+
+/* This function is only called from the init routine so the spinlock
+ * for the unused_write_head list isn't taken
+ */
+static void alloc_write_bufs(void)
+{
+	struct virtio_console_port_buffer *buf;
+	int i;
+
+	for (i = 0; i < 1024; i++) {
+		buf = get_buf(PAGE_SIZE);
+		if (!buf)
+			break;
+		list_add_tail(&buf->next, &virtconsole.unused_write_head);
+	}
+}
+
+static void handle_control_message(struct virtio_console_port *port,
+				   struct virtio_console_control *cpkt)
+{
+	switch (cpkt->event) {
+	case VIRTIO_CONSOLE_PORT_OPEN:
+		port->host_connected = cpkt->value;
+		break;
+	}
+}
+
+static void virtio_console_rx_work_handler(struct work_struct *work)
+{
+	struct virtio_console_port *port;
+	struct virtio_console_port_buffer *buf;
+	struct virtio_console_header header;
+	struct virtqueue *vq;
+	unsigned int tmplen, header_len;
+
+	header_len = use_multiport() ? sizeof(header) : 0;
+
+	port = NULL;
+	vq = virtconsole.in_vq;
+	while ((buf = vq->vq_ops->get_buf(vq, &tmplen))) {
+		/* The buffer is no longer unused */
+		list_del(&buf->next);
+
+		if (use_multiport()) {
+			memcpy(&header, buf->buf, header_len);
+			port = get_port_from_id(header.id);
+		} else
+			port = get_port_from_id(VIRTIO_CONSOLE_CONSOLE_PORT);
+		if (!port) {
+			/* No valid index at start of
+			 * buffer. Drop it.
+			 */
+			pr_debug("%s: invalid index in buffer, %c %d\n",
+				 __func__, buf->buf[0], buf->buf[0]);
+			kfree(buf->buf);
+			kfree(buf);
+			break;
+		}
+		if (use_multiport() && is_internal(header.flags)) {
+			handle_control_message(port,
+					       (struct virtio_console_control *)
+					       (buf->buf + header_len));
+
+			/* OPT: This buffer can be added to the
+			 * unused list to avoid free/alloc
+			 */
+			kfree(buf->buf);
+			kfree(buf);
+		} else {
+			buf->len = tmplen;
+			buf->offset = header_len;
+			list_add_tail(&buf->next, &port->readbuf_head);
+			/* We might have missed a connection
+			 * notification, e.g. before the queues were
+			 * initialised.
+			 */
+			port->host_connected = true;
+		}
+		wake_up_interruptible(&port->waitqueue);
+	}
+	/* hvc_poll takes a spinlock and calls hvc_push which calls
+	 * put_chars which results in a call to send_buf.
+	 *
+	 * It also calls get_chars with the spinlock held.
+	 */
+	if (port && is_console_port(port) && hvc_poll(port->hvc))
 		hvc_kick();
+
+	/* Allocate buffers for all the ones that got used up */
+	fill_receive_queue();
+}
+
+static void virtio_console_tx_work_handler(struct work_struct *work)
+{
+	struct virtqueue *vq;
+	struct virtio_console_port_buffer *buf;
+	unsigned int tmplen;
+
+	vq = virtconsole.out_vq;
+	while ((buf = vq->vq_ops->get_buf(vq, &tmplen))) {
+		/* 0 the buffer to not leak data from other processes */
+		memset(buf->buf, 0, buf->len);
+		spin_lock(&virtconsole.write_list_lock);
+		list_add_tail(&buf->next, &virtconsole.unused_write_head);
+		spin_unlock(&virtconsole.write_list_lock);
+	}
+}
+
+static void rx_intr(struct virtqueue *vq)
+{
+	schedule_work(&virtconsole.rx_work);
+}
+
+static void tx_intr(struct virtqueue *vq)
+{
+	schedule_work(&virtconsole.tx_work);
+}
+
+static void config_intr(struct virtio_device *vdev)
+{
+	/* Handle port hot-add */
+	schedule_work(&virtconsole.config_work);
+
+	/* Handle console size changes */
+	virtcons_apply_config(vdev);
+}
+
+static u32 virtconsole_get_hot_add_port(struct virtio_console_config *config)
+{
+	u32 i;
+	u32 port_nr;
+
+	for (i = 0; i < virtconsole.config->max_nr_ports / 32; i++) {
+		port_nr = ffs(config->ports_map[i] ^ virtconsole.config->ports_map[i]);
+		if (port_nr)
+			break;
+	}
+	if (unlikely(!port_nr))
+		return VIRTIO_CONSOLE_BAD_ID;
+
+	/* We used ffs above */
+	port_nr--;
+
+	/* FIXME: Do this only when add_port is successful */
+	virtconsole.config->ports_map[i] |= 1U << port_nr;
+
+	port_nr += i * 32;
+	return port_nr;
+}
+
+static u32 virtconsole_find_next_port(u32 *map, int *map_i)
+{
+	u32 port_nr;
+
+	while (1) {
+		port_nr = ffs(*map);
+		if (port_nr)
+			break;
+
+		if (unlikely(*map_i >= virtconsole.config->max_nr_ports / 32))
+			return VIRTIO_CONSOLE_BAD_ID;
+		++*map_i;
+		*map = virtconsole.config->ports_map[*map_i];
+	}
+	/* We used ffs above */
+	port_nr--;
+
+	/* FIXME: Do this only when add_port is successful / reset bit
+	 * in config space if add_port was unsuccessful
+	 */
+	*map &= ~(1U << port_nr);
+
+	port_nr += *map_i * 32;
+	return port_nr;
+}
+
+static int virtconsole_add_port(u32 port_nr)
+{
+	struct virtio_console_port *port;
+	dev_t devt;
+	int ret;
+
+	port = kzalloc(sizeof(*port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	devt = MKDEV(major, port_nr);
+	cdev_init(&port->cdev, &virtconsole_fops);
+
+	ret = register_chrdev_region(devt, 1, "virtio-console");
+	if (ret < 0) {
+		pr_err("%s: error registering chrdev region, ret = %d\n",
+		       __func__, ret);
+		goto free_cdev;
+	}
+	ret = cdev_add(&port->cdev, devt, 1);
+	if (ret < 0) {
+		pr_err("%s: error adding cdev, ret = %d\n", __func__, ret);
+		goto free_cdev;
+	}
+	port->dev = device_create(virtconsole.class, NULL, devt, NULL,
+				  "vcon%u", port_nr);
+	if (IS_ERR(port->dev)) {
+		ret = PTR_ERR(port->dev);
+		pr_err("%s: Error creating device, ret = %d\n", __func__, ret);
+		goto free_cdev;
+	}
+	INIT_LIST_HEAD(&port->readbuf_head);
+	init_waitqueue_head(&port->waitqueue);
+
+	list_add_tail(&port->next, &virtconsole.port_head);
+
+	if (is_console_port(port)) {
+		/* 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. */
+		port->hvc = hvc_alloc(port_nr, 0, &virtio_cons, PAGE_SIZE);
+		if (IS_ERR(port->hvc)) {
+			ret = PTR_ERR(port->hvc);
+			goto free_cdev;
+		}
+	}
+	pr_info("virtio-console port found at id %u\n", port_nr);
+
+	return 0;
+free_cdev:
+	unregister_chrdev(major, "virtio-console");
+	return ret;
+}
+
+static u32 get_ports_map_size(u32 max_ports)
+{
+	return sizeof(u32) * ((max_ports + 31) / 32);
+}
+
+static void virtio_console_config_work_handler(struct work_struct *work)
+{
+	struct virtio_console_config *virtconconf;
+	struct virtio_device *vdev = virtconsole.vdev;
+	u32 i, port_nr;
+	int ret;
+
+	virtconconf = kzalloc(sizeof(*virtconconf) +
+			      get_ports_map_size(virtconsole.config->max_nr_ports),
+			      GFP_KERNEL);
+	vdev->config->get(vdev,
+			  offsetof(struct virtio_console_config, nr_active_ports),
+			  &virtconconf->nr_active_ports,
+			  sizeof(virtconconf->nr_active_ports));
+	vdev->config->get(vdev,
+			  offsetof(struct virtio_console_config, ports_map),
+			  virtconconf->ports_map,
+			  get_ports_map_size(virtconsole.config->max_nr_ports));
+
+	/* Hot-add ports */
+	for (i = virtconsole.config->nr_active_ports;
+	     i < virtconconf->nr_active_ports; i++) {
+		port_nr = virtconsole_get_hot_add_port(virtconconf);
+		if (port_nr == VIRTIO_CONSOLE_BAD_ID)
+			continue;
+		ret = virtconsole_add_port(port_nr);
+		if (!ret)
+			virtconsole.config->nr_active_ports++;
+	}
+	kfree(virtconconf);
 }
 
 /*D:370 Once we're further in boot, we get probed like any other virtio device.
@@ -187,64 +811,143 @@ static void hvc_handle_input(struct virtqueue *vq)
  * never remove the console device we never need this pointer again.
  *
  * Finally we put our input buffer in the input queue, ready to receive. */
-static int __devinit virtcons_probe(struct virtio_device *dev)
+static int __devinit virtcons_probe(struct virtio_device *vdev)
 {
-	vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
+	vq_callback_t *callbacks[] = { rx_intr, tx_intr };
 	const char *names[] = { "input", "output" };
 	struct virtqueue *vqs[2];
-	int err;
-
-	vdev = dev;
-
-	/* This is the scratch page we use to receive console input */
-	inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!inbuf) {
-		err = -ENOMEM;
-		goto fail;
+	u32 i, map;
+	int ret, map_i;
+	u32 max_nr_ports;
+	bool multiport;
+
+	virtconsole.vdev = vdev;
+
+	multiport = false;
+	if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
+		multiport = true;
+		vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT;
+		vdev->config->finalize_features(vdev);
+
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_console_config,
+					   max_nr_ports),
+				  &max_nr_ports,
+				  sizeof(max_nr_ports));
+		virtconsole.config = kzalloc(sizeof(struct virtio_console_config)
+					     + get_ports_map_size(max_nr_ports),
+					     GFP_KERNEL);
+		if (!virtconsole.config)
+			return -ENOMEM;
+		virtconsole.config->max_nr_ports = max_nr_ports;
+
+		vdev->config->get(vdev, offsetof(struct virtio_console_config,
+						 nr_active_ports),
+				  &virtconsole.config->nr_active_ports,
+				  sizeof(virtconsole.config->nr_active_ports));
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_console_config,
+					   ports_map),
+				  virtconsole.config->ports_map,
+				  get_ports_map_size(max_nr_ports));
 	}
-
 	/* 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);
-	if (err)
-		goto free;
+	ret = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
+	if (ret)
+		goto fail;
 
-	in_vq = vqs[0];
-	out_vq = vqs[1];
+	virtconsole.in_vq = vqs[0];
+	virtconsole.out_vq = vqs[1];
+
+	INIT_LIST_HEAD(&virtconsole.port_head);
+	INIT_LIST_HEAD(&virtconsole.unused_read_head);
+	INIT_LIST_HEAD(&virtconsole.unused_write_head);
+
+	if (multiport) {
+		map_i = 0;
+		map = virtconsole.config->ports_map[map_i];
+		for (i = 0; i < virtconsole.config->nr_active_ports; i++) {
+			u32 port_nr;
+
+			port_nr = virtconsole_find_next_port(&map, &map_i);
+			if (unlikely(port_nr == VIRTIO_CONSOLE_BAD_ID))
+				continue;
+			virtconsole_add_port(port_nr);
+		}
+	} else
+		virtconsole_add_port(VIRTIO_CONSOLE_CONSOLE_PORT);
+
+	INIT_WORK(&virtconsole.rx_work, &virtio_console_rx_work_handler);
+	INIT_WORK(&virtconsole.tx_work, &virtio_console_tx_work_handler);
+	INIT_WORK(&virtconsole.config_work, &virtio_console_config_work_handler);
+	spin_lock_init(&virtconsole.write_list_lock);
+
+	fill_receive_queue();
+	alloc_write_bufs();
+	return 0;
 
-	/* 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;
+fail:
+	return ret;
+}
+
+static void virtcons_remove_port_data(struct virtio_console_port *port)
+{
+	struct virtio_console_port_buffer *buf, *buf2;
+
+#if 0 /* hvc_console is compiled in, at least on Fedora. */
+	if (is_console_port(port))
+		hvc_remove(hvc);
+#endif
+	device_destroy(virtconsole.class, port->dev->devt);
+	unregister_chrdev_region(port->dev->devt, 1);
+	cdev_del(&port->cdev);
+
+	/* Remove the buffers in which we have unconsumed data */
+	list_for_each_entry_safe(buf, buf2, &port->readbuf_head, next) {
+		list_del(&buf->next);
+		kfree(buf->buf);
+		kfree(buf);
 	}
+}
 
-	/* Register the input buffer the first time. */
-	add_inbuf();
-	return 0;
+static void virtcons_remove(struct virtio_device *vdev)
+{
+	struct virtio_console_port *port, *port2;
+	struct virtio_console_port_buffer *buf, *buf2;
+	char *tmpbuf;
+	int len;
+
+	unregister_chrdev(major, "virtio-console");
+	class_destroy(virtconsole.class);
+
+	cancel_work_sync(&virtconsole.rx_work);
+
+	/* Free up the buffers in the 'received' queue */
+	while ((tmpbuf = virtconsole.in_vq->vq_ops->get_buf(virtconsole.in_vq,
+							    &len)))
+		kfree(tmpbuf);
 
-free_vqs:
 	vdev->config->del_vqs(vdev);
-free:
-	kfree(inbuf);
-fail:
-	return err;
+
+	/* Free up the buffers that were unused */
+	list_for_each_entry_safe(buf, buf2, &virtconsole.unused_read_head, next) {
+		list_del(&buf->next);
+		kfree(buf->buf);
+		kfree(buf);
+	}
+	list_for_each_entry_safe(buf, buf2, &virtconsole.unused_write_head, next) {
+		list_del(&buf->next);
+		kfree(buf->buf);
+		kfree(buf);
+	}
+	list_for_each_entry_safe(port, port2, &virtconsole.port_head, next) {
+		list_del(&port->next);
+		virtcons_remove_port_data(port);
+		kfree(port);
+	}
+	kfree(virtconsole.config);
 }
 
 static struct virtio_device_id id_table[] = {
@@ -254,6 +957,7 @@ 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 = {
@@ -263,14 +967,34 @@ 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)
 {
-	return register_virtio_driver(&virtio_console);
+	int ret;
+
+	virtconsole.class = class_create(THIS_MODULE, "virtio-console");
+	if (IS_ERR(virtconsole.class)) {
+		pr_err("Error creating virtio-console class\n");
+		ret = PTR_ERR(virtconsole.class);
+		return ret;
+	}
+	ret = register_virtio_driver(&virtio_console);
+	if (ret) {
+		class_destroy(virtconsole.class);
+		return ret;
+	}
+	return 0;
+}
+
+static void __exit fini(void)
+{
+	unregister_virtio_driver(&virtio_console);
 }
 module_init(init);
+module_exit(fini);
 
 MODULE_DEVICE_TABLE(virtio, id_table);
 MODULE_DESCRIPTION("Virtio console driver");
diff --git a/include/linux/virtio_console.h b/include/linux/virtio_console.h
index b5f5198..9a3a3b9 100644
--- a/include/linux/virtio_console.h
+++ b/include/linux/virtio_console.h
@@ -7,14 +7,48 @@
 
 /* Feature bits */
 #define VIRTIO_CONSOLE_F_SIZE	0	/* Does host provide console size? */
+#define VIRTIO_CONSOLE_F_MULTIPORT 1	/* Does host provide multiple ports? */
+
+#define VIRTIO_CONSOLE_BAD_ID	(~(u32)0) /* Invalid port number */
+
+/* Port at which the virtio console is spawned */
+#define VIRTIO_CONSOLE_CONSOLE_PORT	0
+#define VIRTIO_CONSOLE_CONSOLE2_PORT	1
 
 struct virtio_console_config {
 	/* colums of the screens */
 	__u16 cols;
 	/* rows of the screens */
 	__u16 rows;
+	/* max. number of ports supported for each PCI device */
+	__u32 max_nr_ports;
+	/* number of ports in use */
+	__u32 nr_active_ports;
+	/* locations of the ports in use */
+	__u32 ports_map[0 /* (max_nr_ports + 31) / 32 */];
+} __attribute__((packed));
+
+struct virtio_console_control {
+	__u16 event;
+	__u16 value;
+};
+
+/* This struct is put in each buffer that gets passed to userspace and
+ * vice-versa
+ */
+struct virtio_console_header {
+	u32 id; /* Port number */
+	u32 flags; /* Some message between host and guest */
+	u32 size; /* Complete size of the write request - only sent
+		   * with the first buffer for each write request
+		   */
 } __attribute__((packed));
 
+/* Messages between host and guest */
+#define VIRTIO_CONSOLE_ID_INTERNAL	(1 << 0)
+
+/* Some events for internal messages */
+#define VIRTIO_CONSOLE_PORT_OPEN	0
 
 #ifdef __KERNEL__
 int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int));
-- 
1.6.2.5

[PATCH 1/1] virtio_console: Add interface for guest and host communication

[Amit Shah]

Expose multiple char devices ("ports") for simple communication
between the host userspace and guest.

Sample offline usages can be: poking around in a guest to find out
the file systems used, applications installed, etc. Online usages
can be sharing of clipboard data between the guest and the host,
sending information about logged-in users to the host, locking the
screen or session when a vnc session is closed, and so on.

The interface presented to guest userspace is of a simple char
device, so it can be used like this:

    fd = open("/dev/vcon2", O_RDWR);
    ret = read(fd, buf, 100);
    ret = write(fd, string, strlen(string));

Each port is to be assigned a unique function, for example, the
first 4 ports may be reserved for libvirt usage, the next 4 for
generic streaming data and so on. This port-function mapping
isn't finalised yet.

For requirements, use-cases and some history see

    http://www.linux-kvm.org/page/VMchannel_Requirements

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 drivers/char/Kconfig           |    4 +-
 drivers/char/virtio_console.c  |  980 ++++++++++++++++++++++++++++++++++------
 include/linux/virtio_console.h |   34 ++
 3 files changed, 889 insertions(+), 129 deletions(-)

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index b8368e2..cbbb9a1 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -678,7 +678,9 @@ config VIRTIO_CONSOLE
 	select HVC_DRIVER
 	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/vconNN will
+	  be created when corresponding ports are found.
 
 config HVCS
 	tristate "IBM Hypervisor Virtual Console Server support"
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 0d328b5..edea6d3 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -13,6 +13,7 @@
  * 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) 2009, Amit Shah, 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
@@ -28,116 +29,395 @@
  * 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/device.h>
 #include <linux/err.h>
+#include <linux/fs.h>
 #include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/spinlock.h>
 #include <linux/virtio.h>
 #include <linux/virtio_ids.h>
 #include <linux/virtio_console.h>
+#include <linux/workqueue.h>
 #include "hvc_console.h"
 
-/*D:340 These represent our input and output console queues, and the virtio
+/*D:340 FIXME 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;
+struct virtio_console_struct {
+	struct work_struct rx_work;
+	struct work_struct tx_work;
+	struct work_struct config_work;
 
-/* This is our input buffer, and how much data is left in it. */
-static unsigned int in_len;
-static char *in, *inbuf;
+	struct list_head port_head;
+	struct list_head unused_read_head;
+	struct list_head unused_write_head;
 
-/* The operations for our console. */
-static struct hv_ops virtio_cons;
+	/* To protect the list of unused write buffers */
+	spinlock_t write_list_lock;
 
-/* The hvc device */
-static struct hvc_struct *hvc;
+	struct virtio_device *vdev;
+	struct class *class;
+	struct virtqueue *in_vq, *out_vq;
 
-/*D:310 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). */
-static int put_chars(u32 vtermno, const char *buf, int count)
+	struct virtio_console_config *config;
+};
+
+/* This struct holds individual buffers received for each port */
+struct virtio_console_port_buffer {
+	struct list_head next;
+
+	char *buf;
+
+	size_t len; /* length of the buffer */
+	size_t offset; /* offset in the buf from which to consume data */
+};
+
+struct virtio_console_port {
+	/* Next port in the list */
+	struct list_head next;
+
+	/* Buffer management */
+	struct list_head readbuf_head;
+	wait_queue_head_t waitqueue;
+
+	/* Each port associates with a separate char device */
+	struct cdev cdev;
+	struct device *dev;
+
+	/* The hvc device, if this port is associated with a console */
+	struct hvc_struct *hvc;
+
+	bool host_connected;  /* Is the host device open */
+};
+
+static struct virtio_console_struct virtconsole;
+
+static int major = 60; /* from the experimental range */
+
+static struct virtio_console_port *get_port_from_id(u32 id)
 {
-	struct scatterlist sg[1];
-	unsigned int len;
-
-	/* 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) {
-		/* 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();
+	struct virtio_console_port *port;
+
+	list_for_each_entry(port, &virtconsole.port_head, next) {
+		if (MINOR(port->dev->devt) == id)
+			return port;
 	}
+	return NULL;
+}
 
-	/* We're expected to return the amount of data we wrote: all of it. */
-	return count;
+static int get_id_from_port(struct virtio_console_port *port)
+{
+	return MINOR(port->dev->devt);
 }
 
-/* Create a scatter-gather list representing our input buffer and put it in the
- * queue. */
-static void add_inbuf(void)
+static bool is_console_port(struct virtio_console_port *port)
 {
-	struct scatterlist sg[1];
-	sg_init_one(sg, inbuf, PAGE_SIZE);
+	u32 port_nr = get_id_from_port(port);
 
-	/* 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);
+	if (port_nr == VIRTIO_CONSOLE_CONSOLE_PORT ||
+	    port_nr == VIRTIO_CONSOLE_CONSOLE2_PORT)
+		return true;
+	return false;
 }
 
-/*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 inline bool use_multiport(void)
 {
-	/* If we don't have an input queue yet, we can't get input. */
-	BUG_ON(!in_vq);
+	/* This condition can be true when put_chars is called from
+	 * early_init
+	 */
+	if (!virtconsole.vdev)
+		return 0;
+	return virtconsole.vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+}
+
+static inline bool is_internal(u32 flags)
+{
+	return flags & VIRTIO_CONSOLE_ID_INTERNAL;
+}
+
+static ssize_t fill_readbuf(struct virtio_console_port *port,
+			    char *out_buf, size_t out_count, bool to_user)
+{
+	struct virtio_console_port_buffer *buf, *buf2;
+	ssize_t out_offset, ret;
+
+	out_offset = 0;
+	list_for_each_entry_safe(buf, buf2, &port->readbuf_head, next) {
+		size_t copy_size;
+
+		copy_size = out_count;
+		if (copy_size > buf->len - buf->offset)
+			copy_size = buf->len - buf->offset;
+
+		if (to_user) {
+			ret = copy_to_user(out_buf + out_offset,
+					   buf->buf + buf->offset,
+					   copy_size);
+			/* FIXME: Deal with ret != 0 */
+		} else {
+			memcpy(out_buf + out_offset,
+			       buf->buf + buf->offset,
+			       copy_size);
+			ret = 0; /* Emulate copy_to_user behaviour */
+		}
+
+		/* Return the number of bytes actually copied */
+		ret = copy_size - ret;
+		buf->offset += ret;
+		out_offset += ret;
+		out_count -= ret;
+
+		if (buf->len - buf->offset == 0) {
+			list_del(&buf->next);
+			kfree(buf->buf);
+			kfree(buf);
+		}
+		if (!out_count)
+			break;
+	}
+	return out_offset;
+}
+
+static bool wait_is_over(struct virtio_console_port *port)
+{
+	return !list_empty(&port->readbuf_head) || !port->host_connected;
+}
 
-	/* No buffer?  Try to get one. */
-	if (!in_len) {
-		in = in_vq->vq_ops->get_buf(in_vq, &in_len);
-		if (!in)
+static ssize_t virtconsole_read(struct file *filp, char __user *ubuf,
+			       size_t count, loff_t *offp)
+{
+	struct virtio_console_port *port;
+	ssize_t ret;
+
+	port = filp->private_data;
+
+	if (list_empty(&port->readbuf_head)) {
+		/* 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 (list_empty(&port->readbuf_head) && !port->host_connected)
+		return 0;
+
+	return fill_readbuf(port, ubuf, count, true);
+}
+
+static ssize_t send_buf(struct virtio_console_port *port,
+			const char *in_buf, size_t in_count,
+			u32 flags, bool from_user)
+{
+	struct virtqueue *out_vq;
+	struct virtio_console_port_buffer *buf, *buf2;
+	struct scatterlist sg[1];
+	struct virtio_console_header header;
+	size_t in_offset, copy_size;
+	ssize_t ret;
+	unsigned int header_len;
+
+	if (!in_count)
+		return 0;
+
+	out_vq = virtconsole.out_vq;
+
+	/* We can't send internal messages to a host that won't understand it */
+	if (!use_multiport() && is_internal(flags))
+		return 0;
+	header_len = 0;
+	if (use_multiport()) {
+		header.id = get_id_from_port(port);
+		header.flags = flags;
+		header.size = in_count;
+		header_len = sizeof(header);
 	}
 
-	/* You want more than we have to give?  Well, try wanting less! */
-	if (in_len < count)
-		count = in_len;
+	in_offset = 0; /* offset in the user buffer */
+	while (in_count - in_offset) {
+		copy_size = min(in_count - in_offset + header_len, PAGE_SIZE);
+
+		spin_lock(&virtconsole.write_list_lock);
+		list_for_each_entry_safe(buf, buf2,
+					 &virtconsole.unused_write_head,
+					 next) {
+			list_del(&buf->next);
+			break;
+		}
+		spin_unlock(&virtconsole.write_list_lock);
+		if (!buf)
+			break;
+		if (header_len) {
+			memcpy(buf->buf, &header, header_len);
+			copy_size -= header_len;
+		}
+		if (from_user)
+			ret = copy_from_user(buf->buf + header_len,
+					     in_buf + in_offset, copy_size);
+		else {
+			/* Since we're not sure when the host will actually
+			 * consume the data and tell us about it, we have
+			 * to copy the data here in case the caller
+			 * frees the in_buf
+			 */
+			memcpy(buf->buf + header_len,
+			       in_buf + in_offset, copy_size);
+			ret = 0; /* Emulate copy_from_user */
+		}
+		buf->len = header_len + copy_size - ret;
+		sg_init_one(sg, buf->buf, buf->len);
+
+		ret = out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, buf);
+		if (ret < 0) {
+			/* FIXME: Put the buf back in the list */
+			break;
+		}
+
+		in_offset += buf->len - header_len;
+		/* Only send size with the first buffer.  This way
+		 * userspace can find out a continuous stream of data
+		 * belonging to one write request and consume it
+		 * appropriately
+		 */
+		header.size = 0;
+
+		/* No space left anyway */
+		if (!ret)
+			break;
+	}
+	/* Tell Host to go! */
+	out_vq->vq_ops->kick(out_vq);
 
-	/* Copy across to their buffer and increment offset. */
-	memcpy(buf, in, count);
-	in += count;
-	in_len -= count;
+	/* We're expected to return the amount of data we wrote */
+	return in_offset;
+}
+
+static ssize_t virtconsole_write(struct file *filp, const char __user *ubuf,
+				 size_t count, loff_t *offp)
+{
+	struct virtio_console_port *port;
 
-	/* Finished?  Re-register buffer so Host will use it again. */
-	if (in_len == 0)
-		add_inbuf();
+	port = filp->private_data;
 
-	return count;
+	return send_buf(port, ubuf, count, 0, true);
 }
-/*:*/
 
-/*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.
+static unsigned int virtconsole_poll(struct file *filp, poll_table *wait)
+{
+	struct virtio_console_port *port;
+	unsigned int ret;
+
+	port = filp->private_data;
+	poll_wait(filp, &port->waitqueue, wait);
+
+	ret = 0;
+	if (!list_empty(&port->readbuf_head))
+		ret |= POLLIN | POLLRDNORM;
+	if (!port->host_connected)
+		ret |= POLLHUP;
+
+	return ret;
+}
+
+static int virtconsole_release(struct inode *inode, struct file *filp)
+{
+	struct virtio_console_control cpkt;
+
+	/* Notify host of port being closed */
+	cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+	cpkt.value = 0;
+	send_buf(filp->private_data, (char *)&cpkt, sizeof(cpkt),
+		 VIRTIO_CONSOLE_ID_INTERNAL, false);
+	return 0;
+}
+
+static int virtconsole_open(struct inode *inode, struct file *filp)
+{
+	struct cdev *cdev = inode->i_cdev;
+	struct virtio_console_port *port;
+	struct virtio_console_control cpkt;
+
+	port = container_of(cdev, struct virtio_console_port, cdev);
+	filp->private_data = port;
+
+	/* Notify host of port being opened */
+	cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+	cpkt.value = 1;
+	send_buf(filp->private_data, (char *)&cpkt, sizeof(cpkt),
+		 VIRTIO_CONSOLE_ID_INTERNAL, false);
+
+	return 0;
+}
+
+static const struct file_operations virtconsole_fops = {
+	.owner = THIS_MODULE,
+	.open  = virtconsole_open,
+	.read  = virtconsole_read,
+	.write = virtconsole_write,
+	.poll  = virtconsole_poll,
+	.release = virtconsole_release,
+};
+
+/*D:310 The cons_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 cons_put_chars(u32 vtermno, const char *buf, int count)
 {
-	virtio_cons.put_chars = put_chars;
-	return hvc_instantiate(0, 0, &virtio_cons);
+	struct virtio_console_port *port;
+
+	port = get_port_from_id(vtermno);
+	if (!port)
+		return 0;
+
+	return send_buf(port, buf, count, 0, false);
 }
 
+/*D:350 cons_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 cons_get_chars(u32 vtermno, char *buf, int count)
+{
+	struct virtio_console_port *port;
+
+	/* If we don't have an input queue yet, we can't get input. */
+	BUG_ON(!virtconsole.in_vq);
+
+	port = get_port_from_id(vtermno);
+	if (!port)
+		return 0;
+
+	if (list_empty(&port->readbuf_head))
+		return 0;
+
+	return fill_readbuf(port, buf, count, false);
+
+}
+/*:*/
+
 /*
  * virtio console configuration. This supports:
  * - console resize
@@ -153,7 +433,11 @@ static void virtcons_apply_config(struct virtio_device *dev)
 		dev->config->get(dev,
 				 offsetof(struct virtio_console_config, rows),
 				 &ws.ws_row, sizeof(u16));
-		hvc_resize(hvc, ws);
+		/* We'll use this way of resizing only for legacy support
+		 * for newer userspace, use internal messages to indicate
+		 * console size changes so that it can be done per-port
+		 */
+		hvc_resize(get_port_from_id(VIRTIO_CONSOLE_CONSOLE_PORT)->hvc, ws);
 	}
 }
 
@@ -161,23 +445,363 @@ static void virtcons_apply_config(struct virtio_device *dev)
  * 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 int notifier_add_vio(struct hvc_struct *hp, int data)
+static int cons_notifier_add_vio(struct hvc_struct *hp, int data)
 {
 	hp->irq_requested = 1;
-	virtcons_apply_config(vdev);
+	virtcons_apply_config(virtconsole.vdev);
 
 	return 0;
 }
 
-static void notifier_del_vio(struct hvc_struct *hp, int data)
+static void cons_notifier_del_vio(struct hvc_struct *hp, int data)
 {
 	hp->irq_requested = 0;
 }
 
-static void hvc_handle_input(struct virtqueue *vq)
+/* The operations for our console. */
+static struct hv_ops virtio_cons = {
+	.get_chars = cons_get_chars,
+	.put_chars = cons_put_chars,
+	.notifier_add = cons_notifier_add_vio,
+	.notifier_del = cons_notifier_del_vio,
+	.notifier_hangup = cons_notifier_del_vio,
+};
+
+/*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);
+}
+
+static struct virtio_console_port_buffer *get_buf(size_t buf_size)
+{
+	struct virtio_console_port_buffer *buf;
+
+	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
+	if (!buf)
+		goto out;
+	buf->buf = kzalloc(buf_size, GFP_KERNEL);
+	if (!buf->buf) {
+		kfree(buf);
+		goto out;
+	}
+	buf->len = buf_size;
+out:
+	return buf;
+}
+
+static void fill_queue(struct virtqueue *vq, size_t buf_size,
+		       struct list_head *unused_head)
 {
-	if (hvc_poll(hvc))
+	struct scatterlist sg[1];
+	struct virtio_console_port_buffer *buf;
+	int ret;
+
+	do {
+		buf = get_buf(buf_size);
+		if (!buf)
+			break;
+		sg_init_one(sg, buf->buf, buf_size);
+
+		ret = vq->vq_ops->add_buf(vq, sg, 0, 1, buf);
+		if (ret < 0) {
+			kfree(buf->buf);
+			kfree(buf);
+			break;
+		}
+		/* We have to keep track of the unused buffers
+		 * so that they can be freed when the module
+		 * is being removed
+		 */
+		list_add_tail(&buf->next, unused_head);
+	} while (ret > 0);
+	vq->vq_ops->kick(vq);
+}
+
+static void fill_receive_queue(void)
+{
+	fill_queue(virtconsole.in_vq, PAGE_SIZE, &virtconsole.unused_read_head);
+}
+
+/* This function is only called from the init routine so the spinlock
+ * for the unused_write_head list isn't taken
+ */
+static void alloc_write_bufs(void)
+{
+	struct virtio_console_port_buffer *buf;
+	int i;
+
+	for (i = 0; i < 1024; i++) {
+		buf = get_buf(PAGE_SIZE);
+		if (!buf)
+			break;
+		list_add_tail(&buf->next, &virtconsole.unused_write_head);
+	}
+}
+
+static void handle_control_message(struct virtio_console_port *port,
+				   struct virtio_console_control *cpkt)
+{
+	switch (cpkt->event) {
+	case VIRTIO_CONSOLE_PORT_OPEN:
+		port->host_connected = cpkt->value;
+		break;
+	}
+}
+
+static void virtio_console_rx_work_handler(struct work_struct *work)
+{
+	struct virtio_console_port *port;
+	struct virtio_console_port_buffer *buf;
+	struct virtio_console_header header;
+	struct virtqueue *vq;
+	unsigned int tmplen, header_len;
+
+	header_len = use_multiport() ? sizeof(header) : 0;
+
+	port = NULL;
+	vq = virtconsole.in_vq;
+	while ((buf = vq->vq_ops->get_buf(vq, &tmplen))) {
+		/* The buffer is no longer unused */
+		list_del(&buf->next);
+
+		if (use_multiport()) {
+			memcpy(&header, buf->buf, header_len);
+			port = get_port_from_id(header.id);
+		} else
+			port = get_port_from_id(VIRTIO_CONSOLE_CONSOLE_PORT);
+		if (!port) {
+			/* No valid index at start of
+			 * buffer. Drop it.
+			 */
+			pr_debug("%s: invalid index in buffer, %c %d\n",
+				 __func__, buf->buf[0], buf->buf[0]);
+			kfree(buf->buf);
+			kfree(buf);
+			break;
+		}
+		if (use_multiport() && is_internal(header.flags)) {
+			handle_control_message(port,
+					       (struct virtio_console_control *)
+					       (buf->buf + header_len));
+
+			/* OPT: This buffer can be added to the
+			 * unused list to avoid free/alloc
+			 */
+			kfree(buf->buf);
+			kfree(buf);
+		} else {
+			buf->len = tmplen;
+			buf->offset = header_len;
+			list_add_tail(&buf->next, &port->readbuf_head);
+			/* We might have missed a connection
+			 * notification, e.g. before the queues were
+			 * initialised.
+			 */
+			port->host_connected = true;
+		}
+		wake_up_interruptible(&port->waitqueue);
+	}
+	/* hvc_poll takes a spinlock and calls hvc_push which calls
+	 * put_chars which results in a call to send_buf.
+	 *
+	 * It also calls get_chars with the spinlock held.
+	 */
+	if (port && is_console_port(port) && hvc_poll(port->hvc))
 		hvc_kick();
+
+	/* Allocate buffers for all the ones that got used up */
+	fill_receive_queue();
+}
+
+static void virtio_console_tx_work_handler(struct work_struct *work)
+{
+	struct virtqueue *vq;
+	struct virtio_console_port_buffer *buf;
+	unsigned int tmplen;
+
+	vq = virtconsole.out_vq;
+	while ((buf = vq->vq_ops->get_buf(vq, &tmplen))) {
+		/* 0 the buffer to not leak data from other processes */
+		memset(buf->buf, 0, buf->len);
+		spin_lock(&virtconsole.write_list_lock);
+		list_add_tail(&buf->next, &virtconsole.unused_write_head);
+		spin_unlock(&virtconsole.write_list_lock);
+	}
+}
+
+static void rx_intr(struct virtqueue *vq)
+{
+	schedule_work(&virtconsole.rx_work);
+}
+
+static void tx_intr(struct virtqueue *vq)
+{
+	schedule_work(&virtconsole.tx_work);
+}
+
+static void config_intr(struct virtio_device *vdev)
+{
+	/* Handle port hot-add */
+	schedule_work(&virtconsole.config_work);
+
+	/* Handle console size changes */
+	virtcons_apply_config(vdev);
+}
+
+static u32 virtconsole_get_hot_add_port(struct virtio_console_config *config)
+{
+	u32 i;
+	u32 port_nr;
+
+	for (i = 0; i < virtconsole.config->max_nr_ports / 32; i++) {
+		port_nr = ffs(config->ports_map[i] ^ virtconsole.config->ports_map[i]);
+		if (port_nr)
+			break;
+	}
+	if (unlikely(!port_nr))
+		return VIRTIO_CONSOLE_BAD_ID;
+
+	/* We used ffs above */
+	port_nr--;
+
+	/* FIXME: Do this only when add_port is successful */
+	virtconsole.config->ports_map[i] |= 1U << port_nr;
+
+	port_nr += i * 32;
+	return port_nr;
+}
+
+static u32 virtconsole_find_next_port(u32 *map, int *map_i)
+{
+	u32 port_nr;
+
+	while (1) {
+		port_nr = ffs(*map);
+		if (port_nr)
+			break;
+
+		if (unlikely(*map_i >= virtconsole.config->max_nr_ports / 32))
+			return VIRTIO_CONSOLE_BAD_ID;
+		++*map_i;
+		*map = virtconsole.config->ports_map[*map_i];
+	}
+	/* We used ffs above */
+	port_nr--;
+
+	/* FIXME: Do this only when add_port is successful / reset bit
+	 * in config space if add_port was unsuccessful
+	 */
+	*map &= ~(1U << port_nr);
+
+	port_nr += *map_i * 32;
+	return port_nr;
+}
+
+static int virtconsole_add_port(u32 port_nr)
+{
+	struct virtio_console_port *port;
+	dev_t devt;
+	int ret;
+
+	port = kzalloc(sizeof(*port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	devt = MKDEV(major, port_nr);
+	cdev_init(&port->cdev, &virtconsole_fops);
+
+	ret = register_chrdev_region(devt, 1, "virtio-console");
+	if (ret < 0) {
+		pr_err("%s: error registering chrdev region, ret = %d\n",
+		       __func__, ret);
+		goto free_cdev;
+	}
+	ret = cdev_add(&port->cdev, devt, 1);
+	if (ret < 0) {
+		pr_err("%s: error adding cdev, ret = %d\n", __func__, ret);
+		goto free_cdev;
+	}
+	port->dev = device_create(virtconsole.class, NULL, devt, NULL,
+				  "vcon%u", port_nr);
+	if (IS_ERR(port->dev)) {
+		ret = PTR_ERR(port->dev);
+		pr_err("%s: Error creating device, ret = %d\n", __func__, ret);
+		goto free_cdev;
+	}
+	INIT_LIST_HEAD(&port->readbuf_head);
+	init_waitqueue_head(&port->waitqueue);
+
+	list_add_tail(&port->next, &virtconsole.port_head);
+
+	if (is_console_port(port)) {
+		/* 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. */
+		port->hvc = hvc_alloc(port_nr, 0, &virtio_cons, PAGE_SIZE);
+		if (IS_ERR(port->hvc)) {
+			ret = PTR_ERR(port->hvc);
+			goto free_cdev;
+		}
+	}
+	pr_info("virtio-console port found at id %u\n", port_nr);
+
+	return 0;
+free_cdev:
+	unregister_chrdev(major, "virtio-console");
+	return ret;
+}
+
+static u32 get_ports_map_size(u32 max_ports)
+{
+	return sizeof(u32) * ((max_ports + 31) / 32);
+}
+
+static void virtio_console_config_work_handler(struct work_struct *work)
+{
+	struct virtio_console_config *virtconconf;
+	struct virtio_device *vdev = virtconsole.vdev;
+	u32 i, port_nr;
+	int ret;
+
+	virtconconf = kzalloc(sizeof(*virtconconf) +
+			      get_ports_map_size(virtconsole.config->max_nr_ports),
+			      GFP_KERNEL);
+	vdev->config->get(vdev,
+			  offsetof(struct virtio_console_config, nr_active_ports),
+			  &virtconconf->nr_active_ports,
+			  sizeof(virtconconf->nr_active_ports));
+	vdev->config->get(vdev,
+			  offsetof(struct virtio_console_config, ports_map),
+			  virtconconf->ports_map,
+			  get_ports_map_size(virtconsole.config->max_nr_ports));
+
+	/* Hot-add ports */
+	for (i = virtconsole.config->nr_active_ports;
+	     i < virtconconf->nr_active_ports; i++) {
+		port_nr = virtconsole_get_hot_add_port(virtconconf);
+		if (port_nr == VIRTIO_CONSOLE_BAD_ID)
+			continue;
+		ret = virtconsole_add_port(port_nr);
+		if (!ret)
+			virtconsole.config->nr_active_ports++;
+	}
+	kfree(virtconconf);
 }
 
 /*D:370 Once we're further in boot, we get probed like any other virtio device.
@@ -187,64 +811,143 @@ static void hvc_handle_input(struct virtqueue *vq)
  * never remove the console device we never need this pointer again.
  *
  * Finally we put our input buffer in the input queue, ready to receive. */
-static int __devinit virtcons_probe(struct virtio_device *dev)
+static int __devinit virtcons_probe(struct virtio_device *vdev)
 {
-	vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
+	vq_callback_t *callbacks[] = { rx_intr, tx_intr };
 	const char *names[] = { "input", "output" };
 	struct virtqueue *vqs[2];
-	int err;
-
-	vdev = dev;
-
-	/* This is the scratch page we use to receive console input */
-	inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!inbuf) {
-		err = -ENOMEM;
-		goto fail;
+	u32 i, map;
+	int ret, map_i;
+	u32 max_nr_ports;
+	bool multiport;
+
+	virtconsole.vdev = vdev;
+
+	multiport = false;
+	if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
+		multiport = true;
+		vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT;
+		vdev->config->finalize_features(vdev);
+
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_console_config,
+					   max_nr_ports),
+				  &max_nr_ports,
+				  sizeof(max_nr_ports));
+		virtconsole.config = kzalloc(sizeof(struct virtio_console_config)
+					     + get_ports_map_size(max_nr_ports),
+					     GFP_KERNEL);
+		if (!virtconsole.config)
+			return -ENOMEM;
+		virtconsole.config->max_nr_ports = max_nr_ports;
+
+		vdev->config->get(vdev, offsetof(struct virtio_console_config,
+						 nr_active_ports),
+				  &virtconsole.config->nr_active_ports,
+				  sizeof(virtconsole.config->nr_active_ports));
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_console_config,
+					   ports_map),
+				  virtconsole.config->ports_map,
+				  get_ports_map_size(max_nr_ports));
 	}
-
 	/* 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);
-	if (err)
-		goto free;
+	ret = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
+	if (ret)
+		goto fail;
 
-	in_vq = vqs[0];
-	out_vq = vqs[1];
+	virtconsole.in_vq = vqs[0];
+	virtconsole.out_vq = vqs[1];
+
+	INIT_LIST_HEAD(&virtconsole.port_head);
+	INIT_LIST_HEAD(&virtconsole.unused_read_head);
+	INIT_LIST_HEAD(&virtconsole.unused_write_head);
+
+	if (multiport) {
+		map_i = 0;
+		map = virtconsole.config->ports_map[map_i];
+		for (i = 0; i < virtconsole.config->nr_active_ports; i++) {
+			u32 port_nr;
+
+			port_nr = virtconsole_find_next_port(&map, &map_i);
+			if (unlikely(port_nr == VIRTIO_CONSOLE_BAD_ID))
+				continue;
+			virtconsole_add_port(port_nr);
+		}
+	} else
+		virtconsole_add_port(VIRTIO_CONSOLE_CONSOLE_PORT);
+
+	INIT_WORK(&virtconsole.rx_work, &virtio_console_rx_work_handler);
+	INIT_WORK(&virtconsole.tx_work, &virtio_console_tx_work_handler);
+	INIT_WORK(&virtconsole.config_work, &virtio_console_config_work_handler);
+	spin_lock_init(&virtconsole.write_list_lock);
+
+	fill_receive_queue();
+	alloc_write_bufs();
+	return 0;
 
-	/* 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;
+fail:
+	return ret;
+}
+
+static void virtcons_remove_port_data(struct virtio_console_port *port)
+{
+	struct virtio_console_port_buffer *buf, *buf2;
+
+#if 0 /* hvc_console is compiled in, at least on Fedora. */
+	if (is_console_port(port))
+		hvc_remove(hvc);
+#endif
+	device_destroy(virtconsole.class, port->dev->devt);
+	unregister_chrdev_region(port->dev->devt, 1);
+	cdev_del(&port->cdev);
+
+	/* Remove the buffers in which we have unconsumed data */
+	list_for_each_entry_safe(buf, buf2, &port->readbuf_head, next) {
+		list_del(&buf->next);
+		kfree(buf->buf);
+		kfree(buf);
 	}
+}
 
-	/* Register the input buffer the first time. */
-	add_inbuf();
-	return 0;
+static void virtcons_remove(struct virtio_device *vdev)
+{
+	struct virtio_console_port *port, *port2;
+	struct virtio_console_port_buffer *buf, *buf2;
+	char *tmpbuf;
+	int len;
+
+	unregister_chrdev(major, "virtio-console");
+	class_destroy(virtconsole.class);
+
+	cancel_work_sync(&virtconsole.rx_work);
+
+	/* Free up the buffers in the 'received' queue */
+	while ((tmpbuf = virtconsole.in_vq->vq_ops->get_buf(virtconsole.in_vq,
+							    &len)))
+		kfree(tmpbuf);
 
-free_vqs:
 	vdev->config->del_vqs(vdev);
-free:
-	kfree(inbuf);
-fail:
-	return err;
+
+	/* Free up the buffers that were unused */
+	list_for_each_entry_safe(buf, buf2, &virtconsole.unused_read_head, next) {
+		list_del(&buf->next);
+		kfree(buf->buf);
+		kfree(buf);
+	}
+	list_for_each_entry_safe(buf, buf2, &virtconsole.unused_write_head, next) {
+		list_del(&buf->next);
+		kfree(buf->buf);
+		kfree(buf);
+	}
+	list_for_each_entry_safe(port, port2, &virtconsole.port_head, next) {
+		list_del(&port->next);
+		virtcons_remove_port_data(port);
+		kfree(port);
+	}
+	kfree(virtconsole.config);
 }
 
 static struct virtio_device_id id_table[] = {
@@ -254,6 +957,7 @@ 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 = {
@@ -263,14 +967,34 @@ 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)
 {
-	return register_virtio_driver(&virtio_console);
+	int ret;
+
+	virtconsole.class = class_create(THIS_MODULE, "virtio-console");
+	if (IS_ERR(virtconsole.class)) {
+		pr_err("Error creating virtio-console class\n");
+		ret = PTR_ERR(virtconsole.class);
+		return ret;
+	}
+	ret = register_virtio_driver(&virtio_console);
+	if (ret) {
+		class_destroy(virtconsole.class);
+		return ret;
+	}
+	return 0;
+}
+
+static void __exit fini(void)
+{
+	unregister_virtio_driver(&virtio_console);
 }
 module_init(init);
+module_exit(fini);
 
 MODULE_DEVICE_TABLE(virtio, id_table);
 MODULE_DESCRIPTION("Virtio console driver");
diff --git a/include/linux/virtio_console.h b/include/linux/virtio_console.h
index b5f5198..9a3a3b9 100644
--- a/include/linux/virtio_console.h
+++ b/include/linux/virtio_console.h
@@ -7,14 +7,48 @@
 
 /* Feature bits */
 #define VIRTIO_CONSOLE_F_SIZE	0	/* Does host provide console size? */
+#define VIRTIO_CONSOLE_F_MULTIPORT 1	/* Does host provide multiple ports? */
+
+#define VIRTIO_CONSOLE_BAD_ID	(~(u32)0) /* Invalid port number */
+
+/* Port at which the virtio console is spawned */
+#define VIRTIO_CONSOLE_CONSOLE_PORT	0
+#define VIRTIO_CONSOLE_CONSOLE2_PORT	1
 
 struct virtio_console_config {
 	/* colums of the screens */
 	__u16 cols;
 	/* rows of the screens */
 	__u16 rows;
+	/* max. number of ports supported for each PCI device */
+	__u32 max_nr_ports;
+	/* number of ports in use */
+	__u32 nr_active_ports;
+	/* locations of the ports in use */
+	__u32 ports_map[0 /* (max_nr_ports + 31) / 32 */];
+} __attribute__((packed));
+
+struct virtio_console_control {
+	__u16 event;
+	__u16 value;
+};
+
+/* This struct is put in each buffer that gets passed to userspace and
+ * vice-versa
+ */
+struct virtio_console_header {
+	u32 id; /* Port number */
+	u32 flags; /* Some message between host and guest */
+	u32 size; /* Complete size of the write request - only sent
+		   * with the first buffer for each write request
+		   */
 } __attribute__((packed));
 
+/* Messages between host and guest */
+#define VIRTIO_CONSOLE_ID_INTERNAL	(1 << 0)
+
+/* Some events for internal messages */
+#define VIRTIO_CONSOLE_PORT_OPEN	0
 
 #ifdef __KERNEL__
 int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int));
-- 
1.6.2.5

[PATCH 1/2] char: Emit 'OPENED' events on char device open

[Amit Shah]

Notify users of the char interface whenever the file / connection is
opened.

The existing RESET event is triggered when the qemu char state is reset
as well; which may not be as interesting as char device open events.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 qemu-char.c |   14 +++++++++++++-
 qemu-char.h |    1 +
 2 files changed, 14 insertions(+), 1 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index c25ed1c..5fe882a 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -474,6 +474,8 @@ static CharDriverState *qemu_chr_open_mux(CharDriverState *drv)
     chr->chr_write = mux_chr_write;
     chr->chr_update_read_handler = mux_chr_update_read_handler;
     chr->chr_accept_input = mux_chr_accept_input;
+
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -622,6 +624,7 @@ static CharDriverState *qemu_chr_open_fd(int fd_in, int fd_out)
     chr->chr_close = fd_chr_close;
 
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
 
     return chr;
 }
@@ -913,8 +916,10 @@ static void pty_chr_state(CharDriverState *chr, int connected)
          * the virtual device linked to our pty. */
         qemu_mod_timer(s->timer, qemu_get_clock(rt_clock) + 1000);
     } else {
-        if (!s->connected)
+        if (!s->connected) {
             qemu_chr_reset(chr);
+            qemu_chr_event(chr, CHR_EVENT_OPENED);
+        }
         s->connected = 1;
     }
 }
@@ -1152,6 +1157,7 @@ static CharDriverState *qemu_chr_open_tty(const char *filename)
     }
     chr->chr_ioctl = tty_serial_ioctl;
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 #else  /* ! __linux__ && ! __sun__ */
@@ -1297,6 +1303,7 @@ static CharDriverState *qemu_chr_open_pp(const char *filename)
     chr->opaque = drv;
 
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
 
     return chr;
 }
@@ -1576,6 +1583,7 @@ static CharDriverState *qemu_chr_open_win(const char *filename)
         return NULL;
     }
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -1675,6 +1683,7 @@ static CharDriverState *qemu_chr_open_win_pipe(const char *filename)
         return NULL;
     }
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -1689,6 +1698,7 @@ static CharDriverState *qemu_chr_open_win_file(HANDLE fd_out)
     chr->opaque = s;
     chr->chr_write = win_chr_write;
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -1823,6 +1833,7 @@ static CharDriverState *qemu_chr_open_udp(const char *def)
     chr->chr_write = udp_chr_write;
     chr->chr_update_read_handler = udp_chr_update_read_handler;
     chr->chr_close = udp_chr_close;
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 
 return_err:
@@ -2029,6 +2040,7 @@ static void tcp_chr_connect(void *opaque)
     qemu_set_fd_handler2(s->fd, tcp_chr_read_poll,
                          tcp_chr_read, NULL, chr);
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
 }
 
 #define IACSET(x,a,b,c) x[0] = a; x[1] = b; x[2] = c;
diff --git a/qemu-char.h b/qemu-char.h
index df620bc..d725d48 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -12,6 +12,7 @@
 #define CHR_EVENT_MUX_IN  3 /* mux-focus was set to this terminal */
 #define CHR_EVENT_MUX_OUT 4 /* mux-focus will move on */
 #define CHR_EVENT_CLOSED  5 /* connection closed */
+#define CHR_EVENT_OPENED  6 /* connection opened */
 
 
 #define CHR_IOCTL_SERIAL_SET_PARAMS   1
-- 
1.6.2.5

[Qemu-devel] [PATCH 1/2] char: Emit 'OPENED' events on char device open

[Amit Shah]

Notify users of the char interface whenever the file / connection is
opened.

The existing RESET event is triggered when the qemu char state is reset
as well; which may not be as interesting as char device open events.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 qemu-char.c |   14 +++++++++++++-
 qemu-char.h |    1 +
 2 files changed, 14 insertions(+), 1 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index c25ed1c..5fe882a 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -474,6 +474,8 @@ static CharDriverState *qemu_chr_open_mux(CharDriverState *drv)
     chr->chr_write = mux_chr_write;
     chr->chr_update_read_handler = mux_chr_update_read_handler;
     chr->chr_accept_input = mux_chr_accept_input;
+
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -622,6 +624,7 @@ static CharDriverState *qemu_chr_open_fd(int fd_in, int fd_out)
     chr->chr_close = fd_chr_close;
 
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
 
     return chr;
 }
@@ -913,8 +916,10 @@ static void pty_chr_state(CharDriverState *chr, int connected)
          * the virtual device linked to our pty. */
         qemu_mod_timer(s->timer, qemu_get_clock(rt_clock) + 1000);
     } else {
-        if (!s->connected)
+        if (!s->connected) {
             qemu_chr_reset(chr);
+            qemu_chr_event(chr, CHR_EVENT_OPENED);
+        }
         s->connected = 1;
     }
 }
@@ -1152,6 +1157,7 @@ static CharDriverState *qemu_chr_open_tty(const char *filename)
     }
     chr->chr_ioctl = tty_serial_ioctl;
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 #else  /* ! __linux__ && ! __sun__ */
@@ -1297,6 +1303,7 @@ static CharDriverState *qemu_chr_open_pp(const char *filename)
     chr->opaque = drv;
 
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
 
     return chr;
 }
@@ -1576,6 +1583,7 @@ static CharDriverState *qemu_chr_open_win(const char *filename)
         return NULL;
     }
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -1675,6 +1683,7 @@ static CharDriverState *qemu_chr_open_win_pipe(const char *filename)
         return NULL;
     }
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -1689,6 +1698,7 @@ static CharDriverState *qemu_chr_open_win_file(HANDLE fd_out)
     chr->opaque = s;
     chr->chr_write = win_chr_write;
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -1823,6 +1833,7 @@ static CharDriverState *qemu_chr_open_udp(const char *def)
     chr->chr_write = udp_chr_write;
     chr->chr_update_read_handler = udp_chr_update_read_handler;
     chr->chr_close = udp_chr_close;
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 
 return_err:
@@ -2029,6 +2040,7 @@ static void tcp_chr_connect(void *opaque)
     qemu_set_fd_handler2(s->fd, tcp_chr_read_poll,
                          tcp_chr_read, NULL, chr);
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
 }
 
 #define IACSET(x,a,b,c) x[0] = a; x[1] = b; x[2] = c;
diff --git a/qemu-char.h b/qemu-char.h
index df620bc..d725d48 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -12,6 +12,7 @@
 #define CHR_EVENT_MUX_IN  3 /* mux-focus was set to this terminal */
 #define CHR_EVENT_MUX_OUT 4 /* mux-focus will move on */
 #define CHR_EVENT_CLOSED  5 /* connection closed */
+#define CHR_EVENT_OPENED  6 /* connection opened */
 
 
 #define CHR_IOCTL_SERIAL_SET_PARAMS   1
-- 
1.6.2.5

[PATCH 1/2] char: Emit 'OPENED' events on char device open

[Amit Shah]

Notify users of the char interface whenever the file / connection is
opened.

The existing RESET event is triggered when the qemu char state is reset
as well; which may not be as interesting as char device open events.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 qemu-char.c |   14 +++++++++++++-
 qemu-char.h |    1 +
 2 files changed, 14 insertions(+), 1 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index c25ed1c..5fe882a 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -474,6 +474,8 @@ static CharDriverState *qemu_chr_open_mux(CharDriverState *drv)
     chr->chr_write = mux_chr_write;
     chr->chr_update_read_handler = mux_chr_update_read_handler;
     chr->chr_accept_input = mux_chr_accept_input;
+
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -622,6 +624,7 @@ static CharDriverState *qemu_chr_open_fd(int fd_in, int fd_out)
     chr->chr_close = fd_chr_close;
 
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
 
     return chr;
 }
@@ -913,8 +916,10 @@ static void pty_chr_state(CharDriverState *chr, int connected)
          * the virtual device linked to our pty. */
         qemu_mod_timer(s->timer, qemu_get_clock(rt_clock) + 1000);
     } else {
-        if (!s->connected)
+        if (!s->connected) {
             qemu_chr_reset(chr);
+            qemu_chr_event(chr, CHR_EVENT_OPENED);
+        }
         s->connected = 1;
     }
 }
@@ -1152,6 +1157,7 @@ static CharDriverState *qemu_chr_open_tty(const char *filename)
     }
     chr->chr_ioctl = tty_serial_ioctl;
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 #else  /* ! __linux__ && ! __sun__ */
@@ -1297,6 +1303,7 @@ static CharDriverState *qemu_chr_open_pp(const char *filename)
     chr->opaque = drv;
 
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
 
     return chr;
 }
@@ -1576,6 +1583,7 @@ static CharDriverState *qemu_chr_open_win(const char *filename)
         return NULL;
     }
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -1675,6 +1683,7 @@ static CharDriverState *qemu_chr_open_win_pipe(const char *filename)
         return NULL;
     }
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -1689,6 +1698,7 @@ static CharDriverState *qemu_chr_open_win_file(HANDLE fd_out)
     chr->opaque = s;
     chr->chr_write = win_chr_write;
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 }
 
@@ -1823,6 +1833,7 @@ static CharDriverState *qemu_chr_open_udp(const char *def)
     chr->chr_write = udp_chr_write;
     chr->chr_update_read_handler = udp_chr_update_read_handler;
     chr->chr_close = udp_chr_close;
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
     return chr;
 
 return_err:
@@ -2029,6 +2040,7 @@ static void tcp_chr_connect(void *opaque)
     qemu_set_fd_handler2(s->fd, tcp_chr_read_poll,
                          tcp_chr_read, NULL, chr);
     qemu_chr_reset(chr);
+    qemu_chr_event(chr, CHR_EVENT_OPENED);
 }
 
 #define IACSET(x,a,b,c) x[0] = a; x[1] = b; x[2] = c;
diff --git a/qemu-char.h b/qemu-char.h
index df620bc..d725d48 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -12,6 +12,7 @@
 #define CHR_EVENT_MUX_IN  3 /* mux-focus was set to this terminal */
 #define CHR_EVENT_MUX_OUT 4 /* mux-focus will move on */
 #define CHR_EVENT_CLOSED  5 /* connection closed */
+#define CHR_EVENT_OPENED  6 /* connection opened */
 
 
 #define CHR_IOCTL_SERIAL_SET_PARAMS   1
-- 
1.6.2.5

[PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

This interface extends the virtio-console device to handle
multiple ports that present a char device from which bits can
be sent and read.

Sample uses for such a device can be obtaining info from the
guest like the file systems used, apps installed, etc. for
offline usage and logged-in users, clipboard copy-paste, etc.
for online usage.

Each port is to be assigned a unique function, for example, the
first 4 ports may be reserved for libvirt usage, the next 4 for
generic streaming data and so on. This port-function mapping
isn't finalised yet.

For requirements, use-cases and some history see

    http://www.linux-kvm.org/page/VMchannel_Requirements

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/pc.c             |   16 +-
 hw/virtio-console.c |  594 ++++++++++++++++++++++++++++++++++++++++++++++-----
 hw/virtio-console.h |   52 +++++
 monitor.c           |    7 +
 qemu-monitor.hx     |   10 +
 qemu-options.hx     |    2 +-
 sysemu.h            |   10 +-
 vl.c                |   41 ++--
 8 files changed, 652 insertions(+), 80 deletions(-)

diff --git a/hw/pc.c b/hw/pc.c
index 503feb0..0e60ecc 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -1462,11 +1462,17 @@ static void pc_init1(ram_addr_t ram_size,
     }
 
     /* Add virtio console devices */
-    if (pci_enabled) {
-        for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
-            if (virtcon_hds[i]) {
-                pci_create_simple(pci_bus, -1, "virtio-console-pci");
-            }
+    if (pci_enabled && virtcon_nr_ports) {
+        void *dev;
+
+        dev = pci_create_simple(pci_bus, -1, "virtio-console-pci");
+        if (!dev) {
+            fprintf(stderr, "qemu: could not create virtio console pci device\n");
+            exit(1);
+        }
+
+        for (i = 0; i < virtcon_nr_ports; i++) {
+                virtio_console_new_port(dev, virtcon_idx[i]);
         }
     }
 
diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index 663c8b9..da590d2 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -2,9 +2,11 @@
  * Virtio Console Device
  *
  * Copyright IBM, Corp. 2008
+ * Copyright Red Hat, Inc. 2009
  *
  * Authors:
  *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
+ *  Amit Shah <amit.shah@redhat.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -12,39 +14,263 @@
  */
 
 #include "hw.h"
+#include "monitor.h"
+#include "pci.h"
+#include "sys-queue.h"
 #include "qemu-char.h"
 #include "virtio.h"
 #include "virtio-console.h"
 
-
 typedef struct VirtIOConsole
 {
     VirtIODevice vdev;
-    VirtQueue *ivq, *dvq;
-    CharDriverState *chr;
+    PCIDevice *dev;
+    VirtQueue *ivq, *ovq;
+    struct VirtIOConsolePort *ports;
+    struct virtio_console_config *config;
+    uint32_t guest_features;
 } VirtIOConsole;
 
-static VirtIOConsole *to_virtio_console(VirtIODevice *vdev)
+/* This struct holds individual buffers received for each port */
+typedef struct VirtIOConsolePortBuffer {
+    TAILQ_ENTRY(VirtIOConsolePortBuffer) next;
+
+    uint8_t *buf;
+
+    size_t len; /* length of the buffer */
+
+    /* The size of one write request as issued by the guest. The
+     * buffer could be split in this list but using the size value in
+     * the first buffer for each write we can identify complete
+     * writes
+     */
+    size_t size;
+} VirtIOConsolePortBuffer;
+
+typedef struct VirtIOConsolePort {
+    VirtIOConsole *vcon;
+    CharDriverState *hd;
+
+    TAILQ_HEAD(, VirtIOConsolePortBuffer) unflushed_buffer_head;
+
+    bool guest_connected;
+    bool host_connected;
+} VirtIOConsolePort;
+
+static VirtIOConsole *virtio_console;
+static struct virtio_console_config virtcon_config;
+static VirtIOConsolePort virtcon_ports[MAX_VIRTIO_CONSOLE_PORTS];
+
+static VirtIOConsolePort *get_port_from_id(uint32_t id)
+{
+    if (id > MAX_VIRTIO_CONSOLE_PORTS)
+        return NULL;
+
+    return &virtcon_ports[id];
+}
+
+static int get_id_from_port(VirtIOConsolePort *port)
+{
+    uint32_t i;
+
+    for (i = 0; i < MAX_VIRTIO_CONSOLE_PORTS; i++) {
+        if (port == &virtcon_ports[i]) {
+            return i;
+        }
+    }
+    return VIRTIO_CONSOLE_BAD_ID;
+}
+
+static bool use_multiport(void)
+{
+    return virtio_console->guest_features & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+}
+
+static bool is_internal(uint32_t flags)
+{
+    return flags & VIRTIO_CONSOLE_ID_INTERNAL;
+}
+
+static bool is_console(uint32_t port_nr)
 {
-    return (VirtIOConsole *)vdev;
+    if (port_nr == VIRTIO_CONSOLE_CONSOLE_PORT ||
+        port_nr == VIRTIO_CONSOLE_CONSOLE2_PORT)
+        return true;
+    return false;
+}
+
+void virtio_console_monitor_command(Monitor *mon,
+                                    const char *command, const char *param)
+{
+    int ret;
+
+    if(!strncmp(command, "add_port", 8)) {
+        if (!param) {
+            monitor_printf(mon, "Error: need port id to add new port\n");
+            return;
+        }
+        ret = init_virtio_console_port(virtcon_nr_ports, param);
+        if (ret < 0) {
+            monitor_printf(mon, "Error: cannot add new port: %s\n",
+                           strerror(-ret));
+            return;
+        }
+        virtio_console_new_port(NULL, virtcon_idx[virtcon_nr_ports]);
+        virtcon_nr_ports++;
+        virtio_console->config->nr_active_ports = cpu_to_le32(virtcon_nr_ports);
+        return;
+    }
+}
+
+static bool has_complete_data(VirtIOConsolePort *port)
+{
+    VirtIOConsolePortBuffer *buf;
+    size_t len, size;
+
+    len = 0;
+    size = 0;
+    TAILQ_FOREACH(buf, &port->unflushed_buffer_head, next) {
+        if (!buf->size && buf == TAILQ_FIRST(&port->unflushed_buffer_head)) {
+            /* We have a buffer that's lost its way; just flush it */
+            return true;
+        }
+        if (size && buf->size) {
+            /* Start of the next write request */
+            return true;
+        }
+        if (buf->size) {
+            size = buf->size;
+        }
+        len += buf->len;
+        if (len == size) {
+            return true;
+        }
+    }
+    return false;
 }
 
+static size_t flush_buf(VirtIOConsolePort *port, const uint8_t *buf, size_t len)
+{
+    if (!port->hd) {
+        return 0;
+    }
+    return qemu_chr_write(port->hd, buf, len);
+}
+
+static void flush_queue(VirtIOConsolePort *port)
+{
+    VirtIOConsolePortBuffer *buf, *buf2;
+    uint8_t *outbuf;
+    size_t outlen;
+
+    while (!TAILQ_EMPTY(&port->unflushed_buffer_head)) {
+        if (!has_complete_data(port)) {
+            break;
+        }
+
+        buf = TAILQ_FIRST(&port->unflushed_buffer_head);
+        if (!buf->size) {
+            /* This is a buf that didn't get consumed as part of a
+             * previous data stream. Bad thing, shouldn't
+             * happen. But let's handle it nonetheless
+             */
+            flush_buf(port, buf->buf, buf->len);
+            TAILQ_REMOVE(&port->unflushed_buffer_head, buf, next);
+            continue;
+        }
+
+        outlen = 0;
+        outbuf = qemu_mallocz(buf->size);
+        TAILQ_FOREACH_SAFE(buf, &port->unflushed_buffer_head, next, buf2) {
+            memcpy(outbuf + outlen, buf->buf, buf->len);
+            outlen += buf->len;
+            TAILQ_REMOVE(&port->unflushed_buffer_head, buf, next);
+        }
+        flush_buf(port, outbuf, outlen);
+        qemu_free(outbuf);
+    }
+}
+
+/* Guest wants to notify us of some event */
+static void handle_control_message(VirtIOConsolePort *port,
+                                   struct virtio_console_control *cpkt)
+{
+    switch(cpkt->event) {
+    case VIRTIO_CONSOLE_PORT_OPEN:
+        port->guest_connected = cpkt->value;
+        break;
+    }
+}
+
+/* Guest wrote something to some port.
+ *
+ * Flush the data in the entire chunk that we received rather than
+ * splitting it into multiple buffers. VNC clients don't consume split
+ * buffers
+ */
 static void virtio_console_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
-    VirtIOConsole *s = to_virtio_console(vdev);
     VirtQueueElement elem;
 
     while (virtqueue_pop(vq, &elem)) {
-        ssize_t len = 0;
-        int d;
+        VirtIOConsolePort *port;
+        VirtIOConsolePortBuffer *buf;
+        struct virtio_console_header header;
+        int header_len;
 
-        for (d = 0; d < elem.out_num; d++) {
-            len += qemu_chr_write(s->chr, (uint8_t *)elem.out_sg[d].iov_base,
-                                  elem.out_sg[d].iov_len);
+        buf = qemu_mallocz(sizeof(*buf));
+
+        if (use_multiport()) {
+            header_len = sizeof(header);
+
+            memcpy(&header, elem.out_sg[0].iov_base, header_len);
+            port = get_port_from_id(header.id);
+            if (!port) {
+                qemu_free(buf);
+                goto next_buf;
+            }
+        } else {
+            header_len = 0;
+            port = get_port_from_id(0);
+        }
+
+        /* The guest always sends only one sg */
+        buf->len = elem.out_sg[0].iov_len - header_len;
+        buf->buf = qemu_mallocz(buf->len);
+        memcpy(buf->buf, elem.out_sg[0].iov_base + header_len, buf->len);
+
+        if (use_multiport() && is_internal(header.flags)) {
+            handle_control_message(port,
+                                   (struct virtio_console_control *)buf->buf);
+            qemu_free(buf->buf);
+            qemu_free(buf);
+            goto next_buf;
         }
-        virtqueue_push(vq, &elem, len);
-        virtio_notify(vdev, vq);
+	if (!use_multiport() || is_console(get_id_from_port(port))) {
+            flush_buf(port, buf->buf, buf->len);
+            qemu_free(buf->buf);
+            qemu_free(buf);
+            goto next_buf;
+        }
+        TAILQ_INSERT_TAIL(&port->unflushed_buffer_head, buf, next);
+        if (use_multiport()) {
+            /* Only the first buffer in a stream will have this
+             * set. This will help us identify the first buffer and
+             * the remaining buffers in the stream based on length
+             */
+            buf->size = header.size;
+        } else {
+            /* We always want to flush all the buffers in this case */
+            buf->size = buf->len;
+        }
+        if (!port->host_connected) {
+            goto next_buf;
+        }
+        flush_queue(port);
+    next_buf:
+        virtqueue_push(vq, &elem, elem.out_sg[0].iov_len);
     }
+    virtio_notify(vdev, vq);
 }
 
 static void virtio_console_handle_input(VirtIODevice *vdev, VirtQueue *vq)
@@ -53,73 +279,329 @@ static void virtio_console_handle_input(VirtIODevice *vdev, VirtQueue *vq)
 
 static uint32_t virtio_console_get_features(VirtIODevice *vdev)
 {
-    return 0;
+    return 1 << VIRTIO_CONSOLE_F_MULTIPORT;
 }
 
-static int vcon_can_read(void *opaque)
+static void virtio_console_set_features(VirtIODevice *vdev, uint32_t features)
 {
-    VirtIOConsole *s = (VirtIOConsole *) opaque;
+    virtio_console->guest_features = features;
+}
 
-    if (!virtio_queue_ready(s->ivq) ||
-        !(s->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
-        virtio_queue_empty(s->ivq))
-        return 0;
+/* Guest requested config info */
+static void virtio_console_get_config(VirtIODevice *vdev, uint8_t *config_data)
+{
+    memcpy(config_data, &virtcon_config, sizeof(struct virtio_console_config));
+}
 
-    /* current implementations have a page sized buffer.
-     * We fall back to a one byte per read if there is not enough room.
-     * It would be cool to have a function that returns the available byte
-     * instead of checking for a limit */
-    if (virtqueue_avail_bytes(s->ivq, TARGET_PAGE_SIZE, 0))
-        return TARGET_PAGE_SIZE;
-    if (virtqueue_avail_bytes(s->ivq, 1, 0))
-        return 1;
-    return 0;
+static void virtio_console_set_config(VirtIODevice *vdev,
+                                      const uint8_t *config_data)
+{
+    struct virtio_console_config config;
+
+    memcpy(&config, config_data, sizeof(config));
 }
 
-static void vcon_read(void *opaque, const uint8_t *buf, int size)
+static void write_to_port(VirtIOConsolePort *port,
+			  const uint8_t *buf, size_t size, uint32_t flags)
 {
-    VirtIOConsole *s = (VirtIOConsole *) opaque;
+    VirtQueue *vq = port->vcon->ivq;
     VirtQueueElement elem;
-    int offset = 0;
+    size_t offset = 0;
+    size_t len = 0;
+
+    if (!virtio_queue_ready(vq)) {
+        return;
+    }
+
+    if (!use_multiport() && is_internal(flags)) {
+        return;
+    }
 
-    /* The current kernel implementation has only one outstanding input
-     * buffer of PAGE_SIZE. Nevertheless, this function is prepared to
-     * handle multiple buffers with multiple sg element for input */
     while (offset < size) {
-        int i = 0;
-        if (!virtqueue_pop(s->ivq, &elem))
-                break;
-        while (offset < size && i < elem.in_num) {
-            int len = MIN(elem.in_sg[i].iov_len, size - offset);
-            memcpy(elem.in_sg[i].iov_base, buf + offset, len);
+        struct virtio_console_header header;
+        int i, header_len;
+
+        header_len = use_multiport() ? sizeof(header) : 0;
+
+        if (!virtqueue_pop(vq, &elem)) {
+            break;
+        }
+        if (elem.in_sg[0].iov_len < header_len) {
+            /* We can't even store our port number in this buffer. Bug? */
+            fprintf(stderr, "virtio-console: size %zd less than expected\n",
+                    elem.in_sg[0].iov_len);
+            exit(1);
+        }
+        header.id = cpu_to_le32(get_id_from_port(port));
+        header.flags = flags;
+        memcpy(elem.in_sg[0].iov_base, &header, header_len);
+
+        for (i = 0; offset < size && i < elem.in_num; i++) {
+            len = MIN(elem.in_sg[i].iov_len - header_len, size - offset);
+
+            memcpy(elem.in_sg[i].iov_base + header_len, buf + offset, len);
             offset += len;
-            i++;
+            header_len = 0;
         }
-        virtqueue_push(s->ivq, &elem, size);
+        header_len = use_multiport() ? sizeof(header) : 0;
+        virtqueue_push(vq, &elem, len + header_len);
+    }
+    virtio_notify(&port->vcon->vdev, vq);
+}
+
+static void send_control_event(VirtIOConsolePort *port,
+                               struct virtio_console_control *cpkt)
+{
+    write_to_port(port, (uint8_t *)cpkt, sizeof(*cpkt),
+                  VIRTIO_CONSOLE_ID_INTERNAL);
+}
+
+/* Readiness of the guest to accept data on a port */
+static int vcon_can_read(void *opaque)
+{
+    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
+    VirtQueue *vq = port->vcon->ivq;
+    int size, header_len;
+
+    if (use_multiport()) {
+        header_len = sizeof(struct virtio_console_header);
+    } else {
+        header_len = 0;
+    }
+
+    if (!virtio_queue_ready(vq) ||
+        !(port->vcon->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
+        virtio_queue_empty(vq)) {
+        return 0;
+    }
+    if (!port->guest_connected) {
+        return 0;
+    }
+    size = TARGET_PAGE_SIZE;
+    if (virtqueue_avail_bytes(vq, size, 0)) {
+        return size - header_len;
+    }
+    size = header_len + 1;
+    if (virtqueue_avail_bytes(vq, size, 0)) {
+        return size - header_len;
     }
-    virtio_notify(&s->vdev, s->ivq);
+    return 0;
+}
+
+/* Send data from a char device over to the guest */
+static void vcon_read(void *opaque, const uint8_t *buf, int size)
+{
+    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
+
+    write_to_port(port, buf, size, 0);
 }
 
 static void vcon_event(void *opaque, int event)
 {
-    /* we will ignore any event for the time being */
+    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
+    struct virtio_console_control cpkt;
+    bool update_needed;
+
+    cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+
+    update_needed = false;
+    switch (event) {
+    case CHR_EVENT_OPENED: {
+        cpkt.value = 1;
+        update_needed = true;
+        port->host_connected = true;
+
+        /* Flush any buffers that were pending while the chardev was
+         * disconnected
+         */
+        flush_queue(port);
+        break;
+    }
+    case CHR_EVENT_CLOSED:
+        cpkt.value = 0;
+        update_needed = true;
+        port->host_connected = false;
+        break;
+    default:
+        break;
+    }
+    if (!update_needed) {
+        return;
+    }
+    send_control_event(port, &cpkt);
+}
+
+static void virtio_console_set_port_active(uint32_t idx)
+{
+    int i = 0;
+
+    while (idx / 32) {
+        i++;
+        idx -= 32;
+    }
+    virtcon_config.ports_map[i] |= 1U << idx;
+}
+
+static bool virtio_console_is_port_active(uint32_t idx)
+{
+    int i = 0;
+
+    while (idx / 32) {
+        i++;
+        idx -= 32;
+    }
+    return virtcon_config.ports_map[i] & (1U << idx);
+}
+
+/* This function gets called from vl.c during initial options
+ * parsing as well as from the monitor to parse the options.
+ * So it's a good idea to not print out anything and just
+ * return values which can become meaningful.
+ */
+int init_virtio_console_port(int port, const char *opts)
+{
+    char dev[256];
+    const char *prot;
+    const char *idx;
+    uint32_t port_nr;
+    int j, k;
+
+    memset(dev, 0, sizeof(dev));
+    prot = strstr(opts, ",protocol=");
+    idx  = strstr(opts, ",port=");
+
+    port_nr = VIRTIO_CONSOLE_CONSOLE_PORT;
+    if (idx) {
+        port_nr = atol(idx + 6); /* skip ',port=' */
+    }
+    if (port_nr >= MAX_VIRTIO_CONSOLE_PORTS) {
+        return -ENOSPC;
+    }
+    if (virtio_console_is_port_active(port_nr)) {
+        return -EEXIST;
+    }
+
+    /* Just to maintain compatibility with other qemu options,
+     * we have the format of
+     *
+     * -virtioconsole unix:/tmp/foo,protocol=bar,port=3
+     *
+     * so to parse the 'unix:', we have to do the following
+     */
+    j = k = 0;
+    while (opts[j] && &opts[j] != prot && &opts[j] != idx) {
+        dev[k++] = opts[j++];
+    }
+
+    if (dev[0] && strncmp(dev, "none", 4)) {
+        char label[32];
+        snprintf(label, sizeof(label), "virtcon%u", port_nr);
+        virtcon_hds[port] = qemu_chr_open(label, dev, NULL);
+        if (!virtcon_hds[port]) {
+            return -EIO;
+        }
+    }
+    virtcon_idx[port] = port_nr;
+    /* The guest never opens the 'vcon device; it instead uses hvc.
+     * To ensure reads don't block in vcons_can_read on guest_connected,
+     * set it here
+     */
+    if (is_console(port_nr)) {
+        virtcon_ports[port_nr].guest_connected = true;
+    }
+    virtio_console_set_port_active(port_nr);
+
+    return 0;
+}
+
+void *virtio_console_new_port(PCIDevice *dev, uint32_t idx)
+{
+    VirtIOConsolePort *port;
+
+    port = get_port_from_id(idx);
+    port->vcon = virtio_console;
+
+    if (!port->vcon->dev && !dev) {
+        return NULL;
+    }
+    if (!port->vcon->dev) {
+        port->vcon->dev = dev;
+    }
+    /* Hot-adding ports to existing device */
+    if (!dev) {
+        dev = port->vcon->dev;
+    }
+    port->hd = qdev_init_chardev(&dev->qdev);
+    if (port->hd) {
+        qemu_chr_add_handlers(port->hd, vcon_can_read, vcon_read, vcon_event,
+                              port);
+    }
+    TAILQ_INIT(&port->unflushed_buffer_head);
+    /* Send an update to the guest about this new port added */
+    virtio_notify_config(&port->vcon->vdev);
+    return port;
 }
 
 static void virtio_console_save(QEMUFile *f, void *opaque)
 {
     VirtIOConsole *s = opaque;
+    unsigned int i;
 
+    /* The virtio device */
     virtio_save(&s->vdev, f);
+    /* The PCI device */
+    pci_device_save(s->dev, f);
+    /* The config space */
+    qemu_put_be16s(f, &virtcon_config.cols);
+    qemu_put_be16s(f, &virtcon_config.rows);
+    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
+    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
+    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
+        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
+    }
+    /* Items in struct VirtIOConsole */
+    qemu_put_be32s(f, &virtio_console->guest_features);
+    /* Items in struct VirtIOConsolePort */
+    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
+        qemu_put_byte(f, virtcon_ports[i].guest_connected);
+    }
 }
 
 static int virtio_console_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIOConsole *s = opaque;
+    unsigned int i;
+    int ret;
 
-    if (version_id != 1)
+    if (version_id > 2)
         return -EINVAL;
 
+    /* The virtio device */
     virtio_load(&s->vdev, f);
+
+    if (version_id < 2)
+        return 0;
+
+    /* The PCI device */
+    ret = pci_device_load(s->dev, f);
+    if (ret < 0) {
+        return ret;
+    }
+    /* The config space */
+    qemu_get_be16s(f, &virtcon_config.cols);
+    qemu_get_be16s(f, &virtcon_config.rows);
+    virtcon_config.max_nr_ports = cpu_to_le32(qemu_get_be32(f));
+    virtcon_config.nr_active_ports = cpu_to_le32(qemu_get_be32(f));
+    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
+        qemu_get_be32s(f, &virtcon_config.ports_map[i]);
+    }
+    /* Items in struct VirtIOConsole */
+    qemu_get_be32s(f, &virtio_console->guest_features);
+    /* Items in struct VirtIOConsolePort */
+    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
+        virtcon_ports[i].guest_connected = qemu_get_byte(f);
+    }
+
     return 0;
 }
 
@@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
     VirtIOConsole *s;
     s = (VirtIOConsole *)virtio_common_init("virtio-console",
                                             VIRTIO_ID_CONSOLE,
-                                            0, sizeof(VirtIOConsole));
+                                            sizeof(struct virtio_console_config),
+                                            sizeof(VirtIOConsole));
     if (s == NULL)
         return NULL;
 
+    virtio_console = s;
     s->vdev.get_features = virtio_console_get_features;
+    s->vdev.set_features = virtio_console_set_features;
+    s->vdev.get_config = virtio_console_get_config;
+    s->vdev.set_config = virtio_console_set_config;
 
+    /* Add queue for host to guest transfers */
     s->ivq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_input);
-    s->dvq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_output);
+    /* Add queue for guest to host transfers */
+    s->ovq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_output);
+
+    s->ports = virtcon_ports;
+    s->config = &virtcon_config;
 
-    s->chr = qdev_init_chardev(dev);
-    qemu_chr_add_handlers(s->chr, vcon_can_read, vcon_read, vcon_event, s);
+    register_savevm("virtio-console", -1, 2, virtio_console_save, virtio_console_load, s);
 
-    register_savevm("virtio-console", -1, 1, virtio_console_save, virtio_console_load, s);
+    virtcon_config.max_nr_ports = cpu_to_le32(MAX_VIRTIO_CONSOLE_PORTS);
+    virtcon_config.nr_active_ports = cpu_to_le32(virtcon_nr_ports);
 
     return &s->vdev;
 }
diff --git a/hw/virtio-console.h b/hw/virtio-console.h
index 84d0717..18b3a96 100644
--- a/hw/virtio-console.h
+++ b/hw/virtio-console.h
@@ -2,9 +2,11 @@
  * Virtio Console Support
  *
  * Copyright IBM, Corp. 2008
+ * Copyright Red Hat, Inc. 2009
  *
  * Authors:
  *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
+ *  Amit Shah <amit.shah@redhat.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -13,7 +15,57 @@
 #ifndef _QEMU_VIRTIO_CONSOLE_H
 #define _QEMU_VIRTIO_CONSOLE_H
 
+#include "sysemu.h"
+
+/* Interface shared between the guest kernel and qemu */
+
 /* The ID for virtio console */
 #define VIRTIO_ID_CONSOLE 3
 
+/* Invalid port number */
+#define VIRTIO_CONSOLE_BAD_ID		(~(uint32_t)0)
+
+/* Port number at which the console is spawned */
+#define VIRTIO_CONSOLE_CONSOLE_PORT	0
+#define VIRTIO_CONSOLE_CONSOLE2_PORT	1
+
+/* Features supported */
+#define VIRTIO_CONSOLE_F_MULTIPORT	1
+
+struct virtio_console_config
+{
+    /* These two fields are used by VIRTIO_CONSOLE_F_SIZE which
+     * isn't implemented here yet
+     */
+    uint16_t cols;
+    uint16_t rows;
+
+    uint32_t max_nr_ports;
+    uint32_t nr_active_ports;
+    uint32_t ports_map[(MAX_VIRTIO_CONSOLE_PORTS + 31) / 32];
+} __attribute__((packed));
+
+struct virtio_console_control
+{
+    uint16_t event;
+    uint16_t value;
+};
+
+struct virtio_console_header {
+    uint32_t id; /* Port id */
+    uint32_t flags; /* Some message between host and guest */
+    uint32_t size; /* Size that's sent with the first buffer of each stream */
+} __attribute__((packed));
+
+/* Messages between host and guest */
+#define VIRTIO_CONSOLE_ID_INTERNAL	(1 << 0)
+
+/* Some events for the internal messages (control packets) */
+#define VIRTIO_CONSOLE_PORT_OPEN	0
+
+
+/* In-qemu interface */
+void virtio_console_monitor_command(Monitor *mon,
+				    const char *command, const char *param);
+
 #endif
diff --git a/monitor.c b/monitor.c
index f2e0455..c909acf 100644
--- a/monitor.c
+++ b/monitor.c
@@ -45,6 +45,7 @@
 #include "kvm.h"
 #include "acl.h"
 #include "exec-all.h"
+#include "hw/virtio-console.h"
 
 #include "qemu-kvm.h"
 
@@ -1769,6 +1770,12 @@ int monitor_get_fd(Monitor *mon, const char *fdname)
     return -1;
 }
 
+static void do_virtio_console_action(Monitor *mon,
+                                     const char *command, const char *param)
+{
+    virtio_console_monitor_command(mon, command, param);
+}
+
 static const mon_cmd_t mon_cmds[] = {
 #include "qemu-monitor.h"
     { NULL, NULL, },
diff --git a/qemu-monitor.hx b/qemu-monitor.hx
index c193a1e..905cb4c 100644
--- a/qemu-monitor.hx
+++ b/qemu-monitor.hx
@@ -572,6 +572,16 @@ STEXI
 Change watchdog action.
 ETEXI
 
+    { "virtio-console", "ss?", do_virtio_console_action,
+      "<command> [<parameters>]\n",
+      "virtio-serial write port=3,key=get,value=clipboard\n"
+      "virtio-serial add_port\n"
+      "virtio-serial add_port port=6,name=foo,protocol=keyvalue\n" },
+STEXI
+@item virtio-console
+Hot-add ports or send data to virtio-console port
+ETEXI
+
     { "acl_show", "s", do_acl_show, "aclname",
       "list rules in the access control list" },
 STEXI
diff --git a/qemu-options.hx b/qemu-options.hx
index ade1663..a2a7629 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1594,7 +1594,7 @@ ETEXI
 
 DEF("virtioconsole", HAS_ARG, QEMU_OPTION_virtiocon, \
     "-virtioconsole c\n" \
-    "                set virtio console\n")
+    "                define virtio console\n")
 STEXI
 @item -virtioconsole @var{c}
 Set virtio console.
diff --git a/sysemu.h b/sysemu.h
index 8a2874a..109b8e7 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -2,6 +2,7 @@
 #define SYSEMU_H
 /* Misc. things related to the system emulator.  */
 
+#include <stdbool.h>
 #include "qemu-common.h"
 #include "qemu-option.h"
 #include "sys-queue.h"
@@ -230,9 +231,14 @@ extern CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
 
 /* virtio consoles */
 
-#define MAX_VIRTIO_CONSOLES 1
+#define MAX_VIRTIO_CONSOLE_PORTS 64
+#define VIRTIO_CONSOLE_PROTO_MAX_LEN 30
 
-extern CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
+extern CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLE_PORTS];
+extern uint32_t virtcon_idx[MAX_VIRTIO_CONSOLE_PORTS];
+extern int virtcon_nr_ports;
+extern int init_virtio_console_port(int port, const char *opts);
+extern void *virtio_console_new_port(PCIDevice *dev, uint32_t idx);
 
 #define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
 
diff --git a/vl.c b/vl.c
index 5d2f359..54ea583 100644
--- a/vl.c
+++ b/vl.c
@@ -211,7 +211,10 @@ static int no_frame = 0;
 int no_quit = 0;
 CharDriverState *serial_hds[MAX_SERIAL_PORTS];
 CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
-CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
+CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLE_PORTS];
+char virtcon_prot[MAX_VIRTIO_CONSOLE_PORTS][VIRTIO_CONSOLE_PROTO_MAX_LEN];
+uint32_t virtcon_idx[MAX_VIRTIO_CONSOLE_PORTS];
+int virtcon_nr_ports;
 #ifdef TARGET_I386
 int win2k_install_hack = 0;
 int rtc_td_hack = 0;
@@ -4843,8 +4846,7 @@ int main(int argc, char **argv, char **envp)
     int serial_device_index;
     const char *parallel_devices[MAX_PARALLEL_PORTS];
     int parallel_device_index;
-    const char *virtio_consoles[MAX_VIRTIO_CONSOLES];
-    int virtio_console_index;
+    const char *virtio_consoles[MAX_VIRTIO_CONSOLE_PORTS];
     const char *loadvm = NULL;
     QEMUMachine *machine;
     const char *cpu_model;
@@ -4918,9 +4920,9 @@ int main(int argc, char **argv, char **envp)
         parallel_devices[i] = NULL;
     parallel_device_index = 0;
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++)
+    for(i = 0; i < MAX_VIRTIO_CONSOLE_PORTS; i++)
         virtio_consoles[i] = NULL;
-    virtio_console_index = 0;
+    virtcon_nr_ports = 0;
 
     for (i = 0; i < MAX_NODES; i++) {
         node_mem[i] = 0;
@@ -5360,12 +5362,12 @@ int main(int argc, char **argv, char **envp)
                 }
                 break;
             case QEMU_OPTION_virtiocon:
-                if (virtio_console_index >= MAX_VIRTIO_CONSOLES) {
+                if (virtcon_nr_ports >= MAX_VIRTIO_CONSOLE_PORTS) {
                     fprintf(stderr, "qemu: too many virtio consoles\n");
                     exit(1);
                 }
-                virtio_consoles[virtio_console_index] = optarg;
-                virtio_console_index++;
+                virtio_consoles[virtcon_nr_ports] = optarg;
+                virtcon_nr_ports++;
                 break;
             case QEMU_OPTION_parallel:
                 if (parallel_device_index >= MAX_PARALLEL_PORTS) {
@@ -5960,17 +5962,13 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
-        const char *devname = virtio_consoles[i];
-        if (devname && strcmp(devname, "none")) {
-            char label[32];
-            snprintf(label, sizeof(label), "virtcon%d", i);
-            virtcon_hds[i] = qemu_chr_open(label, devname, NULL);
-            if (!virtcon_hds[i]) {
-                fprintf(stderr, "qemu: could not open virtio console '%s'\n",
-                        devname);
-                exit(1);
-            }
+    for (i = 0; i < virtcon_nr_ports; i++) {
+        int ret;
+
+        ret = init_virtio_console_port(i, virtio_consoles[i]);
+        if (ret < 0) {
+            fprintf(stderr, "qemu: could not init virtio console port at \"%s\"\n", virtio_consoles[i]);
+            exit(1);
         }
     }
 
@@ -6085,11 +6083,12 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
+    for(i = 0; i < MAX_VIRTIO_CONSOLE_PORTS; i++) {
         const char *devname = virtio_consoles[i];
         if (virtcon_hds[i] && devname) {
             if (strstart(devname, "vc", 0))
-                qemu_chr_printf(virtcon_hds[i], "virtio console%d\r\n", i);
+                qemu_chr_printf(virtcon_hds[i], "virtio console%d\r\n",
+                                virtcon_idx[i]);
         }
     }
 
-- 
1.6.2.5

[Qemu-devel] [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

This interface extends the virtio-console device to handle
multiple ports that present a char device from which bits can
be sent and read.

Sample uses for such a device can be obtaining info from the
guest like the file systems used, apps installed, etc. for
offline usage and logged-in users, clipboard copy-paste, etc.
for online usage.

Each port is to be assigned a unique function, for example, the
first 4 ports may be reserved for libvirt usage, the next 4 for
generic streaming data and so on. This port-function mapping
isn't finalised yet.

For requirements, use-cases and some history see

    http://www.linux-kvm.org/page/VMchannel_Requirements

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/pc.c             |   16 +-
 hw/virtio-console.c |  594 ++++++++++++++++++++++++++++++++++++++++++++++-----
 hw/virtio-console.h |   52 +++++
 monitor.c           |    7 +
 qemu-monitor.hx     |   10 +
 qemu-options.hx     |    2 +-
 sysemu.h            |   10 +-
 vl.c                |   41 ++--
 8 files changed, 652 insertions(+), 80 deletions(-)

diff --git a/hw/pc.c b/hw/pc.c
index 503feb0..0e60ecc 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -1462,11 +1462,17 @@ static void pc_init1(ram_addr_t ram_size,
     }
 
     /* Add virtio console devices */
-    if (pci_enabled) {
-        for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
-            if (virtcon_hds[i]) {
-                pci_create_simple(pci_bus, -1, "virtio-console-pci");
-            }
+    if (pci_enabled && virtcon_nr_ports) {
+        void *dev;
+
+        dev = pci_create_simple(pci_bus, -1, "virtio-console-pci");
+        if (!dev) {
+            fprintf(stderr, "qemu: could not create virtio console pci device\n");
+            exit(1);
+        }
+
+        for (i = 0; i < virtcon_nr_ports; i++) {
+                virtio_console_new_port(dev, virtcon_idx[i]);
         }
     }
 
diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index 663c8b9..da590d2 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -2,9 +2,11 @@
  * Virtio Console Device
  *
  * Copyright IBM, Corp. 2008
+ * Copyright Red Hat, Inc. 2009
  *
  * Authors:
  *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
+ *  Amit Shah <amit.shah@redhat.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -12,39 +14,263 @@
  */
 
 #include "hw.h"
+#include "monitor.h"
+#include "pci.h"
+#include "sys-queue.h"
 #include "qemu-char.h"
 #include "virtio.h"
 #include "virtio-console.h"
 
-
 typedef struct VirtIOConsole
 {
     VirtIODevice vdev;
-    VirtQueue *ivq, *dvq;
-    CharDriverState *chr;
+    PCIDevice *dev;
+    VirtQueue *ivq, *ovq;
+    struct VirtIOConsolePort *ports;
+    struct virtio_console_config *config;
+    uint32_t guest_features;
 } VirtIOConsole;
 
-static VirtIOConsole *to_virtio_console(VirtIODevice *vdev)
+/* This struct holds individual buffers received for each port */
+typedef struct VirtIOConsolePortBuffer {
+    TAILQ_ENTRY(VirtIOConsolePortBuffer) next;
+
+    uint8_t *buf;
+
+    size_t len; /* length of the buffer */
+
+    /* The size of one write request as issued by the guest. The
+     * buffer could be split in this list but using the size value in
+     * the first buffer for each write we can identify complete
+     * writes
+     */
+    size_t size;
+} VirtIOConsolePortBuffer;
+
+typedef struct VirtIOConsolePort {
+    VirtIOConsole *vcon;
+    CharDriverState *hd;
+
+    TAILQ_HEAD(, VirtIOConsolePortBuffer) unflushed_buffer_head;
+
+    bool guest_connected;
+    bool host_connected;
+} VirtIOConsolePort;
+
+static VirtIOConsole *virtio_console;
+static struct virtio_console_config virtcon_config;
+static VirtIOConsolePort virtcon_ports[MAX_VIRTIO_CONSOLE_PORTS];
+
+static VirtIOConsolePort *get_port_from_id(uint32_t id)
+{
+    if (id > MAX_VIRTIO_CONSOLE_PORTS)
+        return NULL;
+
+    return &virtcon_ports[id];
+}
+
+static int get_id_from_port(VirtIOConsolePort *port)
+{
+    uint32_t i;
+
+    for (i = 0; i < MAX_VIRTIO_CONSOLE_PORTS; i++) {
+        if (port == &virtcon_ports[i]) {
+            return i;
+        }
+    }
+    return VIRTIO_CONSOLE_BAD_ID;
+}
+
+static bool use_multiport(void)
+{
+    return virtio_console->guest_features & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+}
+
+static bool is_internal(uint32_t flags)
+{
+    return flags & VIRTIO_CONSOLE_ID_INTERNAL;
+}
+
+static bool is_console(uint32_t port_nr)
 {
-    return (VirtIOConsole *)vdev;
+    if (port_nr == VIRTIO_CONSOLE_CONSOLE_PORT ||
+        port_nr == VIRTIO_CONSOLE_CONSOLE2_PORT)
+        return true;
+    return false;
+}
+
+void virtio_console_monitor_command(Monitor *mon,
+                                    const char *command, const char *param)
+{
+    int ret;
+
+    if(!strncmp(command, "add_port", 8)) {
+        if (!param) {
+            monitor_printf(mon, "Error: need port id to add new port\n");
+            return;
+        }
+        ret = init_virtio_console_port(virtcon_nr_ports, param);
+        if (ret < 0) {
+            monitor_printf(mon, "Error: cannot add new port: %s\n",
+                           strerror(-ret));
+            return;
+        }
+        virtio_console_new_port(NULL, virtcon_idx[virtcon_nr_ports]);
+        virtcon_nr_ports++;
+        virtio_console->config->nr_active_ports = cpu_to_le32(virtcon_nr_ports);
+        return;
+    }
+}
+
+static bool has_complete_data(VirtIOConsolePort *port)
+{
+    VirtIOConsolePortBuffer *buf;
+    size_t len, size;
+
+    len = 0;
+    size = 0;
+    TAILQ_FOREACH(buf, &port->unflushed_buffer_head, next) {
+        if (!buf->size && buf == TAILQ_FIRST(&port->unflushed_buffer_head)) {
+            /* We have a buffer that's lost its way; just flush it */
+            return true;
+        }
+        if (size && buf->size) {
+            /* Start of the next write request */
+            return true;
+        }
+        if (buf->size) {
+            size = buf->size;
+        }
+        len += buf->len;
+        if (len == size) {
+            return true;
+        }
+    }
+    return false;
 }
 
+static size_t flush_buf(VirtIOConsolePort *port, const uint8_t *buf, size_t len)
+{
+    if (!port->hd) {
+        return 0;
+    }
+    return qemu_chr_write(port->hd, buf, len);
+}
+
+static void flush_queue(VirtIOConsolePort *port)
+{
+    VirtIOConsolePortBuffer *buf, *buf2;
+    uint8_t *outbuf;
+    size_t outlen;
+
+    while (!TAILQ_EMPTY(&port->unflushed_buffer_head)) {
+        if (!has_complete_data(port)) {
+            break;
+        }
+
+        buf = TAILQ_FIRST(&port->unflushed_buffer_head);
+        if (!buf->size) {
+            /* This is a buf that didn't get consumed as part of a
+             * previous data stream. Bad thing, shouldn't
+             * happen. But let's handle it nonetheless
+             */
+            flush_buf(port, buf->buf, buf->len);
+            TAILQ_REMOVE(&port->unflushed_buffer_head, buf, next);
+            continue;
+        }
+
+        outlen = 0;
+        outbuf = qemu_mallocz(buf->size);
+        TAILQ_FOREACH_SAFE(buf, &port->unflushed_buffer_head, next, buf2) {
+            memcpy(outbuf + outlen, buf->buf, buf->len);
+            outlen += buf->len;
+            TAILQ_REMOVE(&port->unflushed_buffer_head, buf, next);
+        }
+        flush_buf(port, outbuf, outlen);
+        qemu_free(outbuf);
+    }
+}
+
+/* Guest wants to notify us of some event */
+static void handle_control_message(VirtIOConsolePort *port,
+                                   struct virtio_console_control *cpkt)
+{
+    switch(cpkt->event) {
+    case VIRTIO_CONSOLE_PORT_OPEN:
+        port->guest_connected = cpkt->value;
+        break;
+    }
+}
+
+/* Guest wrote something to some port.
+ *
+ * Flush the data in the entire chunk that we received rather than
+ * splitting it into multiple buffers. VNC clients don't consume split
+ * buffers
+ */
 static void virtio_console_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
-    VirtIOConsole *s = to_virtio_console(vdev);
     VirtQueueElement elem;
 
     while (virtqueue_pop(vq, &elem)) {
-        ssize_t len = 0;
-        int d;
+        VirtIOConsolePort *port;
+        VirtIOConsolePortBuffer *buf;
+        struct virtio_console_header header;
+        int header_len;
 
-        for (d = 0; d < elem.out_num; d++) {
-            len += qemu_chr_write(s->chr, (uint8_t *)elem.out_sg[d].iov_base,
-                                  elem.out_sg[d].iov_len);
+        buf = qemu_mallocz(sizeof(*buf));
+
+        if (use_multiport()) {
+            header_len = sizeof(header);
+
+            memcpy(&header, elem.out_sg[0].iov_base, header_len);
+            port = get_port_from_id(header.id);
+            if (!port) {
+                qemu_free(buf);
+                goto next_buf;
+            }
+        } else {
+            header_len = 0;
+            port = get_port_from_id(0);
+        }
+
+        /* The guest always sends only one sg */
+        buf->len = elem.out_sg[0].iov_len - header_len;
+        buf->buf = qemu_mallocz(buf->len);
+        memcpy(buf->buf, elem.out_sg[0].iov_base + header_len, buf->len);
+
+        if (use_multiport() && is_internal(header.flags)) {
+            handle_control_message(port,
+                                   (struct virtio_console_control *)buf->buf);
+            qemu_free(buf->buf);
+            qemu_free(buf);
+            goto next_buf;
         }
-        virtqueue_push(vq, &elem, len);
-        virtio_notify(vdev, vq);
+	if (!use_multiport() || is_console(get_id_from_port(port))) {
+            flush_buf(port, buf->buf, buf->len);
+            qemu_free(buf->buf);
+            qemu_free(buf);
+            goto next_buf;
+        }
+        TAILQ_INSERT_TAIL(&port->unflushed_buffer_head, buf, next);
+        if (use_multiport()) {
+            /* Only the first buffer in a stream will have this
+             * set. This will help us identify the first buffer and
+             * the remaining buffers in the stream based on length
+             */
+            buf->size = header.size;
+        } else {
+            /* We always want to flush all the buffers in this case */
+            buf->size = buf->len;
+        }
+        if (!port->host_connected) {
+            goto next_buf;
+        }
+        flush_queue(port);
+    next_buf:
+        virtqueue_push(vq, &elem, elem.out_sg[0].iov_len);
     }
+    virtio_notify(vdev, vq);
 }
 
 static void virtio_console_handle_input(VirtIODevice *vdev, VirtQueue *vq)
@@ -53,73 +279,329 @@ static void virtio_console_handle_input(VirtIODevice *vdev, VirtQueue *vq)
 
 static uint32_t virtio_console_get_features(VirtIODevice *vdev)
 {
-    return 0;
+    return 1 << VIRTIO_CONSOLE_F_MULTIPORT;
 }
 
-static int vcon_can_read(void *opaque)
+static void virtio_console_set_features(VirtIODevice *vdev, uint32_t features)
 {
-    VirtIOConsole *s = (VirtIOConsole *) opaque;
+    virtio_console->guest_features = features;
+}
 
-    if (!virtio_queue_ready(s->ivq) ||
-        !(s->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
-        virtio_queue_empty(s->ivq))
-        return 0;
+/* Guest requested config info */
+static void virtio_console_get_config(VirtIODevice *vdev, uint8_t *config_data)
+{
+    memcpy(config_data, &virtcon_config, sizeof(struct virtio_console_config));
+}
 
-    /* current implementations have a page sized buffer.
-     * We fall back to a one byte per read if there is not enough room.
-     * It would be cool to have a function that returns the available byte
-     * instead of checking for a limit */
-    if (virtqueue_avail_bytes(s->ivq, TARGET_PAGE_SIZE, 0))
-        return TARGET_PAGE_SIZE;
-    if (virtqueue_avail_bytes(s->ivq, 1, 0))
-        return 1;
-    return 0;
+static void virtio_console_set_config(VirtIODevice *vdev,
+                                      const uint8_t *config_data)
+{
+    struct virtio_console_config config;
+
+    memcpy(&config, config_data, sizeof(config));
 }
 
-static void vcon_read(void *opaque, const uint8_t *buf, int size)
+static void write_to_port(VirtIOConsolePort *port,
+			  const uint8_t *buf, size_t size, uint32_t flags)
 {
-    VirtIOConsole *s = (VirtIOConsole *) opaque;
+    VirtQueue *vq = port->vcon->ivq;
     VirtQueueElement elem;
-    int offset = 0;
+    size_t offset = 0;
+    size_t len = 0;
+
+    if (!virtio_queue_ready(vq)) {
+        return;
+    }
+
+    if (!use_multiport() && is_internal(flags)) {
+        return;
+    }
 
-    /* The current kernel implementation has only one outstanding input
-     * buffer of PAGE_SIZE. Nevertheless, this function is prepared to
-     * handle multiple buffers with multiple sg element for input */
     while (offset < size) {
-        int i = 0;
-        if (!virtqueue_pop(s->ivq, &elem))
-                break;
-        while (offset < size && i < elem.in_num) {
-            int len = MIN(elem.in_sg[i].iov_len, size - offset);
-            memcpy(elem.in_sg[i].iov_base, buf + offset, len);
+        struct virtio_console_header header;
+        int i, header_len;
+
+        header_len = use_multiport() ? sizeof(header) : 0;
+
+        if (!virtqueue_pop(vq, &elem)) {
+            break;
+        }
+        if (elem.in_sg[0].iov_len < header_len) {
+            /* We can't even store our port number in this buffer. Bug? */
+            fprintf(stderr, "virtio-console: size %zd less than expected\n",
+                    elem.in_sg[0].iov_len);
+            exit(1);
+        }
+        header.id = cpu_to_le32(get_id_from_port(port));
+        header.flags = flags;
+        memcpy(elem.in_sg[0].iov_base, &header, header_len);
+
+        for (i = 0; offset < size && i < elem.in_num; i++) {
+            len = MIN(elem.in_sg[i].iov_len - header_len, size - offset);
+
+            memcpy(elem.in_sg[i].iov_base + header_len, buf + offset, len);
             offset += len;
-            i++;
+            header_len = 0;
         }
-        virtqueue_push(s->ivq, &elem, size);
+        header_len = use_multiport() ? sizeof(header) : 0;
+        virtqueue_push(vq, &elem, len + header_len);
+    }
+    virtio_notify(&port->vcon->vdev, vq);
+}
+
+static void send_control_event(VirtIOConsolePort *port,
+                               struct virtio_console_control *cpkt)
+{
+    write_to_port(port, (uint8_t *)cpkt, sizeof(*cpkt),
+                  VIRTIO_CONSOLE_ID_INTERNAL);
+}
+
+/* Readiness of the guest to accept data on a port */
+static int vcon_can_read(void *opaque)
+{
+    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
+    VirtQueue *vq = port->vcon->ivq;
+    int size, header_len;
+
+    if (use_multiport()) {
+        header_len = sizeof(struct virtio_console_header);
+    } else {
+        header_len = 0;
+    }
+
+    if (!virtio_queue_ready(vq) ||
+        !(port->vcon->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
+        virtio_queue_empty(vq)) {
+        return 0;
+    }
+    if (!port->guest_connected) {
+        return 0;
+    }
+    size = TARGET_PAGE_SIZE;
+    if (virtqueue_avail_bytes(vq, size, 0)) {
+        return size - header_len;
+    }
+    size = header_len + 1;
+    if (virtqueue_avail_bytes(vq, size, 0)) {
+        return size - header_len;
     }
-    virtio_notify(&s->vdev, s->ivq);
+    return 0;
+}
+
+/* Send data from a char device over to the guest */
+static void vcon_read(void *opaque, const uint8_t *buf, int size)
+{
+    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
+
+    write_to_port(port, buf, size, 0);
 }
 
 static void vcon_event(void *opaque, int event)
 {
-    /* we will ignore any event for the time being */
+    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
+    struct virtio_console_control cpkt;
+    bool update_needed;
+
+    cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+
+    update_needed = false;
+    switch (event) {
+    case CHR_EVENT_OPENED: {
+        cpkt.value = 1;
+        update_needed = true;
+        port->host_connected = true;
+
+        /* Flush any buffers that were pending while the chardev was
+         * disconnected
+         */
+        flush_queue(port);
+        break;
+    }
+    case CHR_EVENT_CLOSED:
+        cpkt.value = 0;
+        update_needed = true;
+        port->host_connected = false;
+        break;
+    default:
+        break;
+    }
+    if (!update_needed) {
+        return;
+    }
+    send_control_event(port, &cpkt);
+}
+
+static void virtio_console_set_port_active(uint32_t idx)
+{
+    int i = 0;
+
+    while (idx / 32) {
+        i++;
+        idx -= 32;
+    }
+    virtcon_config.ports_map[i] |= 1U << idx;
+}
+
+static bool virtio_console_is_port_active(uint32_t idx)
+{
+    int i = 0;
+
+    while (idx / 32) {
+        i++;
+        idx -= 32;
+    }
+    return virtcon_config.ports_map[i] & (1U << idx);
+}
+
+/* This function gets called from vl.c during initial options
+ * parsing as well as from the monitor to parse the options.
+ * So it's a good idea to not print out anything and just
+ * return values which can become meaningful.
+ */
+int init_virtio_console_port(int port, const char *opts)
+{
+    char dev[256];
+    const char *prot;
+    const char *idx;
+    uint32_t port_nr;
+    int j, k;
+
+    memset(dev, 0, sizeof(dev));
+    prot = strstr(opts, ",protocol=");
+    idx  = strstr(opts, ",port=");
+
+    port_nr = VIRTIO_CONSOLE_CONSOLE_PORT;
+    if (idx) {
+        port_nr = atol(idx + 6); /* skip ',port=' */
+    }
+    if (port_nr >= MAX_VIRTIO_CONSOLE_PORTS) {
+        return -ENOSPC;
+    }
+    if (virtio_console_is_port_active(port_nr)) {
+        return -EEXIST;
+    }
+
+    /* Just to maintain compatibility with other qemu options,
+     * we have the format of
+     *
+     * -virtioconsole unix:/tmp/foo,protocol=bar,port=3
+     *
+     * so to parse the 'unix:', we have to do the following
+     */
+    j = k = 0;
+    while (opts[j] && &opts[j] != prot && &opts[j] != idx) {
+        dev[k++] = opts[j++];
+    }
+
+    if (dev[0] && strncmp(dev, "none", 4)) {
+        char label[32];
+        snprintf(label, sizeof(label), "virtcon%u", port_nr);
+        virtcon_hds[port] = qemu_chr_open(label, dev, NULL);
+        if (!virtcon_hds[port]) {
+            return -EIO;
+        }
+    }
+    virtcon_idx[port] = port_nr;
+    /* The guest never opens the 'vcon device; it instead uses hvc.
+     * To ensure reads don't block in vcons_can_read on guest_connected,
+     * set it here
+     */
+    if (is_console(port_nr)) {
+        virtcon_ports[port_nr].guest_connected = true;
+    }
+    virtio_console_set_port_active(port_nr);
+
+    return 0;
+}
+
+void *virtio_console_new_port(PCIDevice *dev, uint32_t idx)
+{
+    VirtIOConsolePort *port;
+
+    port = get_port_from_id(idx);
+    port->vcon = virtio_console;
+
+    if (!port->vcon->dev && !dev) {
+        return NULL;
+    }
+    if (!port->vcon->dev) {
+        port->vcon->dev = dev;
+    }
+    /* Hot-adding ports to existing device */
+    if (!dev) {
+        dev = port->vcon->dev;
+    }
+    port->hd = qdev_init_chardev(&dev->qdev);
+    if (port->hd) {
+        qemu_chr_add_handlers(port->hd, vcon_can_read, vcon_read, vcon_event,
+                              port);
+    }
+    TAILQ_INIT(&port->unflushed_buffer_head);
+    /* Send an update to the guest about this new port added */
+    virtio_notify_config(&port->vcon->vdev);
+    return port;
 }
 
 static void virtio_console_save(QEMUFile *f, void *opaque)
 {
     VirtIOConsole *s = opaque;
+    unsigned int i;
 
+    /* The virtio device */
     virtio_save(&s->vdev, f);
+    /* The PCI device */
+    pci_device_save(s->dev, f);
+    /* The config space */
+    qemu_put_be16s(f, &virtcon_config.cols);
+    qemu_put_be16s(f, &virtcon_config.rows);
+    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
+    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
+    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
+        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
+    }
+    /* Items in struct VirtIOConsole */
+    qemu_put_be32s(f, &virtio_console->guest_features);
+    /* Items in struct VirtIOConsolePort */
+    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
+        qemu_put_byte(f, virtcon_ports[i].guest_connected);
+    }
 }
 
 static int virtio_console_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIOConsole *s = opaque;
+    unsigned int i;
+    int ret;
 
-    if (version_id != 1)
+    if (version_id > 2)
         return -EINVAL;
 
+    /* The virtio device */
     virtio_load(&s->vdev, f);
+
+    if (version_id < 2)
+        return 0;
+
+    /* The PCI device */
+    ret = pci_device_load(s->dev, f);
+    if (ret < 0) {
+        return ret;
+    }
+    /* The config space */
+    qemu_get_be16s(f, &virtcon_config.cols);
+    qemu_get_be16s(f, &virtcon_config.rows);
+    virtcon_config.max_nr_ports = cpu_to_le32(qemu_get_be32(f));
+    virtcon_config.nr_active_ports = cpu_to_le32(qemu_get_be32(f));
+    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
+        qemu_get_be32s(f, &virtcon_config.ports_map[i]);
+    }
+    /* Items in struct VirtIOConsole */
+    qemu_get_be32s(f, &virtio_console->guest_features);
+    /* Items in struct VirtIOConsolePort */
+    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
+        virtcon_ports[i].guest_connected = qemu_get_byte(f);
+    }
+
     return 0;
 }
 
@@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
     VirtIOConsole *s;
     s = (VirtIOConsole *)virtio_common_init("virtio-console",
                                             VIRTIO_ID_CONSOLE,
-                                            0, sizeof(VirtIOConsole));
+                                            sizeof(struct virtio_console_config),
+                                            sizeof(VirtIOConsole));
     if (s == NULL)
         return NULL;
 
+    virtio_console = s;
     s->vdev.get_features = virtio_console_get_features;
+    s->vdev.set_features = virtio_console_set_features;
+    s->vdev.get_config = virtio_console_get_config;
+    s->vdev.set_config = virtio_console_set_config;
 
+    /* Add queue for host to guest transfers */
     s->ivq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_input);
-    s->dvq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_output);
+    /* Add queue for guest to host transfers */
+    s->ovq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_output);
+
+    s->ports = virtcon_ports;
+    s->config = &virtcon_config;
 
-    s->chr = qdev_init_chardev(dev);
-    qemu_chr_add_handlers(s->chr, vcon_can_read, vcon_read, vcon_event, s);
+    register_savevm("virtio-console", -1, 2, virtio_console_save, virtio_console_load, s);
 
-    register_savevm("virtio-console", -1, 1, virtio_console_save, virtio_console_load, s);
+    virtcon_config.max_nr_ports = cpu_to_le32(MAX_VIRTIO_CONSOLE_PORTS);
+    virtcon_config.nr_active_ports = cpu_to_le32(virtcon_nr_ports);
 
     return &s->vdev;
 }
diff --git a/hw/virtio-console.h b/hw/virtio-console.h
index 84d0717..18b3a96 100644
--- a/hw/virtio-console.h
+++ b/hw/virtio-console.h
@@ -2,9 +2,11 @@
  * Virtio Console Support
  *
  * Copyright IBM, Corp. 2008
+ * Copyright Red Hat, Inc. 2009
  *
  * Authors:
  *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
+ *  Amit Shah <amit.shah@redhat.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -13,7 +15,57 @@
 #ifndef _QEMU_VIRTIO_CONSOLE_H
 #define _QEMU_VIRTIO_CONSOLE_H
 
+#include "sysemu.h"
+
+/* Interface shared between the guest kernel and qemu */
+
 /* The ID for virtio console */
 #define VIRTIO_ID_CONSOLE 3
 
+/* Invalid port number */
+#define VIRTIO_CONSOLE_BAD_ID		(~(uint32_t)0)
+
+/* Port number at which the console is spawned */
+#define VIRTIO_CONSOLE_CONSOLE_PORT	0
+#define VIRTIO_CONSOLE_CONSOLE2_PORT	1
+
+/* Features supported */
+#define VIRTIO_CONSOLE_F_MULTIPORT	1
+
+struct virtio_console_config
+{
+    /* These two fields are used by VIRTIO_CONSOLE_F_SIZE which
+     * isn't implemented here yet
+     */
+    uint16_t cols;
+    uint16_t rows;
+
+    uint32_t max_nr_ports;
+    uint32_t nr_active_ports;
+    uint32_t ports_map[(MAX_VIRTIO_CONSOLE_PORTS + 31) / 32];
+} __attribute__((packed));
+
+struct virtio_console_control
+{
+    uint16_t event;
+    uint16_t value;
+};
+
+struct virtio_console_header {
+    uint32_t id; /* Port id */
+    uint32_t flags; /* Some message between host and guest */
+    uint32_t size; /* Size that's sent with the first buffer of each stream */
+} __attribute__((packed));
+
+/* Messages between host and guest */
+#define VIRTIO_CONSOLE_ID_INTERNAL	(1 << 0)
+
+/* Some events for the internal messages (control packets) */
+#define VIRTIO_CONSOLE_PORT_OPEN	0
+
+
+/* In-qemu interface */
+void virtio_console_monitor_command(Monitor *mon,
+				    const char *command, const char *param);
+
 #endif
diff --git a/monitor.c b/monitor.c
index f2e0455..c909acf 100644
--- a/monitor.c
+++ b/monitor.c
@@ -45,6 +45,7 @@
 #include "kvm.h"
 #include "acl.h"
 #include "exec-all.h"
+#include "hw/virtio-console.h"
 
 #include "qemu-kvm.h"
 
@@ -1769,6 +1770,12 @@ int monitor_get_fd(Monitor *mon, const char *fdname)
     return -1;
 }
 
+static void do_virtio_console_action(Monitor *mon,
+                                     const char *command, const char *param)
+{
+    virtio_console_monitor_command(mon, command, param);
+}
+
 static const mon_cmd_t mon_cmds[] = {
 #include "qemu-monitor.h"
     { NULL, NULL, },
diff --git a/qemu-monitor.hx b/qemu-monitor.hx
index c193a1e..905cb4c 100644
--- a/qemu-monitor.hx
+++ b/qemu-monitor.hx
@@ -572,6 +572,16 @@ STEXI
 Change watchdog action.
 ETEXI
 
+    { "virtio-console", "ss?", do_virtio_console_action,
+      "<command> [<parameters>]\n",
+      "virtio-serial write port=3,key=get,value=clipboard\n"
+      "virtio-serial add_port\n"
+      "virtio-serial add_port port=6,name=foo,protocol=keyvalue\n" },
+STEXI
+@item virtio-console
+Hot-add ports or send data to virtio-console port
+ETEXI
+
     { "acl_show", "s", do_acl_show, "aclname",
       "list rules in the access control list" },
 STEXI
diff --git a/qemu-options.hx b/qemu-options.hx
index ade1663..a2a7629 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1594,7 +1594,7 @@ ETEXI
 
 DEF("virtioconsole", HAS_ARG, QEMU_OPTION_virtiocon, \
     "-virtioconsole c\n" \
-    "                set virtio console\n")
+    "                define virtio console\n")
 STEXI
 @item -virtioconsole @var{c}
 Set virtio console.
diff --git a/sysemu.h b/sysemu.h
index 8a2874a..109b8e7 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -2,6 +2,7 @@
 #define SYSEMU_H
 /* Misc. things related to the system emulator.  */
 
+#include <stdbool.h>
 #include "qemu-common.h"
 #include "qemu-option.h"
 #include "sys-queue.h"
@@ -230,9 +231,14 @@ extern CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
 
 /* virtio consoles */
 
-#define MAX_VIRTIO_CONSOLES 1
+#define MAX_VIRTIO_CONSOLE_PORTS 64
+#define VIRTIO_CONSOLE_PROTO_MAX_LEN 30
 
-extern CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
+extern CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLE_PORTS];
+extern uint32_t virtcon_idx[MAX_VIRTIO_CONSOLE_PORTS];
+extern int virtcon_nr_ports;
+extern int init_virtio_console_port(int port, const char *opts);
+extern void *virtio_console_new_port(PCIDevice *dev, uint32_t idx);
 
 #define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
 
diff --git a/vl.c b/vl.c
index 5d2f359..54ea583 100644
--- a/vl.c
+++ b/vl.c
@@ -211,7 +211,10 @@ static int no_frame = 0;
 int no_quit = 0;
 CharDriverState *serial_hds[MAX_SERIAL_PORTS];
 CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
-CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
+CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLE_PORTS];
+char virtcon_prot[MAX_VIRTIO_CONSOLE_PORTS][VIRTIO_CONSOLE_PROTO_MAX_LEN];
+uint32_t virtcon_idx[MAX_VIRTIO_CONSOLE_PORTS];
+int virtcon_nr_ports;
 #ifdef TARGET_I386
 int win2k_install_hack = 0;
 int rtc_td_hack = 0;
@@ -4843,8 +4846,7 @@ int main(int argc, char **argv, char **envp)
     int serial_device_index;
     const char *parallel_devices[MAX_PARALLEL_PORTS];
     int parallel_device_index;
-    const char *virtio_consoles[MAX_VIRTIO_CONSOLES];
-    int virtio_console_index;
+    const char *virtio_consoles[MAX_VIRTIO_CONSOLE_PORTS];
     const char *loadvm = NULL;
     QEMUMachine *machine;
     const char *cpu_model;
@@ -4918,9 +4920,9 @@ int main(int argc, char **argv, char **envp)
         parallel_devices[i] = NULL;
     parallel_device_index = 0;
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++)
+    for(i = 0; i < MAX_VIRTIO_CONSOLE_PORTS; i++)
         virtio_consoles[i] = NULL;
-    virtio_console_index = 0;
+    virtcon_nr_ports = 0;
 
     for (i = 0; i < MAX_NODES; i++) {
         node_mem[i] = 0;
@@ -5360,12 +5362,12 @@ int main(int argc, char **argv, char **envp)
                 }
                 break;
             case QEMU_OPTION_virtiocon:
-                if (virtio_console_index >= MAX_VIRTIO_CONSOLES) {
+                if (virtcon_nr_ports >= MAX_VIRTIO_CONSOLE_PORTS) {
                     fprintf(stderr, "qemu: too many virtio consoles\n");
                     exit(1);
                 }
-                virtio_consoles[virtio_console_index] = optarg;
-                virtio_console_index++;
+                virtio_consoles[virtcon_nr_ports] = optarg;
+                virtcon_nr_ports++;
                 break;
             case QEMU_OPTION_parallel:
                 if (parallel_device_index >= MAX_PARALLEL_PORTS) {
@@ -5960,17 +5962,13 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
-        const char *devname = virtio_consoles[i];
-        if (devname && strcmp(devname, "none")) {
-            char label[32];
-            snprintf(label, sizeof(label), "virtcon%d", i);
-            virtcon_hds[i] = qemu_chr_open(label, devname, NULL);
-            if (!virtcon_hds[i]) {
-                fprintf(stderr, "qemu: could not open virtio console '%s'\n",
-                        devname);
-                exit(1);
-            }
+    for (i = 0; i < virtcon_nr_ports; i++) {
+        int ret;
+
+        ret = init_virtio_console_port(i, virtio_consoles[i]);
+        if (ret < 0) {
+            fprintf(stderr, "qemu: could not init virtio console port at \"%s\"\n", virtio_consoles[i]);
+            exit(1);
         }
     }
 
@@ -6085,11 +6083,12 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
+    for(i = 0; i < MAX_VIRTIO_CONSOLE_PORTS; i++) {
         const char *devname = virtio_consoles[i];
         if (virtcon_hds[i] && devname) {
             if (strstart(devname, "vc", 0))
-                qemu_chr_printf(virtcon_hds[i], "virtio console%d\r\n", i);
+                qemu_chr_printf(virtcon_hds[i], "virtio console%d\r\n",
+                                virtcon_idx[i]);
         }
     }
 
-- 
1.6.2.5

[PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

This interface extends the virtio-console device to handle
multiple ports that present a char device from which bits can
be sent and read.

Sample uses for such a device can be obtaining info from the
guest like the file systems used, apps installed, etc. for
offline usage and logged-in users, clipboard copy-paste, etc.
for online usage.

Each port is to be assigned a unique function, for example, the
first 4 ports may be reserved for libvirt usage, the next 4 for
generic streaming data and so on. This port-function mapping
isn't finalised yet.

For requirements, use-cases and some history see

    http://www.linux-kvm.org/page/VMchannel_Requirements

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/pc.c             |   16 +-
 hw/virtio-console.c |  594 ++++++++++++++++++++++++++++++++++++++++++++++-----
 hw/virtio-console.h |   52 +++++
 monitor.c           |    7 +
 qemu-monitor.hx     |   10 +
 qemu-options.hx     |    2 +-
 sysemu.h            |   10 +-
 vl.c                |   41 ++--
 8 files changed, 652 insertions(+), 80 deletions(-)

diff --git a/hw/pc.c b/hw/pc.c
index 503feb0..0e60ecc 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -1462,11 +1462,17 @@ static void pc_init1(ram_addr_t ram_size,
     }
 
     /* Add virtio console devices */
-    if (pci_enabled) {
-        for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
-            if (virtcon_hds[i]) {
-                pci_create_simple(pci_bus, -1, "virtio-console-pci");
-            }
+    if (pci_enabled && virtcon_nr_ports) {
+        void *dev;
+
+        dev = pci_create_simple(pci_bus, -1, "virtio-console-pci");
+        if (!dev) {
+            fprintf(stderr, "qemu: could not create virtio console pci device\n");
+            exit(1);
+        }
+
+        for (i = 0; i < virtcon_nr_ports; i++) {
+                virtio_console_new_port(dev, virtcon_idx[i]);
         }
     }
 
diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index 663c8b9..da590d2 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -2,9 +2,11 @@
  * Virtio Console Device
  *
  * Copyright IBM, Corp. 2008
+ * Copyright Red Hat, Inc. 2009
  *
  * Authors:
  *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
+ *  Amit Shah <amit.shah@redhat.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -12,39 +14,263 @@
  */
 
 #include "hw.h"
+#include "monitor.h"
+#include "pci.h"
+#include "sys-queue.h"
 #include "qemu-char.h"
 #include "virtio.h"
 #include "virtio-console.h"
 
-
 typedef struct VirtIOConsole
 {
     VirtIODevice vdev;
-    VirtQueue *ivq, *dvq;
-    CharDriverState *chr;
+    PCIDevice *dev;
+    VirtQueue *ivq, *ovq;
+    struct VirtIOConsolePort *ports;
+    struct virtio_console_config *config;
+    uint32_t guest_features;
 } VirtIOConsole;
 
-static VirtIOConsole *to_virtio_console(VirtIODevice *vdev)
+/* This struct holds individual buffers received for each port */
+typedef struct VirtIOConsolePortBuffer {
+    TAILQ_ENTRY(VirtIOConsolePortBuffer) next;
+
+    uint8_t *buf;
+
+    size_t len; /* length of the buffer */
+
+    /* The size of one write request as issued by the guest. The
+     * buffer could be split in this list but using the size value in
+     * the first buffer for each write we can identify complete
+     * writes
+     */
+    size_t size;
+} VirtIOConsolePortBuffer;
+
+typedef struct VirtIOConsolePort {
+    VirtIOConsole *vcon;
+    CharDriverState *hd;
+
+    TAILQ_HEAD(, VirtIOConsolePortBuffer) unflushed_buffer_head;
+
+    bool guest_connected;
+    bool host_connected;
+} VirtIOConsolePort;
+
+static VirtIOConsole *virtio_console;
+static struct virtio_console_config virtcon_config;
+static VirtIOConsolePort virtcon_ports[MAX_VIRTIO_CONSOLE_PORTS];
+
+static VirtIOConsolePort *get_port_from_id(uint32_t id)
+{
+    if (id > MAX_VIRTIO_CONSOLE_PORTS)
+        return NULL;
+
+    return &virtcon_ports[id];
+}
+
+static int get_id_from_port(VirtIOConsolePort *port)
+{
+    uint32_t i;
+
+    for (i = 0; i < MAX_VIRTIO_CONSOLE_PORTS; i++) {
+        if (port == &virtcon_ports[i]) {
+            return i;
+        }
+    }
+    return VIRTIO_CONSOLE_BAD_ID;
+}
+
+static bool use_multiport(void)
+{
+    return virtio_console->guest_features & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+}
+
+static bool is_internal(uint32_t flags)
+{
+    return flags & VIRTIO_CONSOLE_ID_INTERNAL;
+}
+
+static bool is_console(uint32_t port_nr)
 {
-    return (VirtIOConsole *)vdev;
+    if (port_nr == VIRTIO_CONSOLE_CONSOLE_PORT ||
+        port_nr == VIRTIO_CONSOLE_CONSOLE2_PORT)
+        return true;
+    return false;
+}
+
+void virtio_console_monitor_command(Monitor *mon,
+                                    const char *command, const char *param)
+{
+    int ret;
+
+    if(!strncmp(command, "add_port", 8)) {
+        if (!param) {
+            monitor_printf(mon, "Error: need port id to add new port\n");
+            return;
+        }
+        ret = init_virtio_console_port(virtcon_nr_ports, param);
+        if (ret < 0) {
+            monitor_printf(mon, "Error: cannot add new port: %s\n",
+                           strerror(-ret));
+            return;
+        }
+        virtio_console_new_port(NULL, virtcon_idx[virtcon_nr_ports]);
+        virtcon_nr_ports++;
+        virtio_console->config->nr_active_ports = cpu_to_le32(virtcon_nr_ports);
+        return;
+    }
+}
+
+static bool has_complete_data(VirtIOConsolePort *port)
+{
+    VirtIOConsolePortBuffer *buf;
+    size_t len, size;
+
+    len = 0;
+    size = 0;
+    TAILQ_FOREACH(buf, &port->unflushed_buffer_head, next) {
+        if (!buf->size && buf == TAILQ_FIRST(&port->unflushed_buffer_head)) {
+            /* We have a buffer that's lost its way; just flush it */
+            return true;
+        }
+        if (size && buf->size) {
+            /* Start of the next write request */
+            return true;
+        }
+        if (buf->size) {
+            size = buf->size;
+        }
+        len += buf->len;
+        if (len == size) {
+            return true;
+        }
+    }
+    return false;
 }
 
+static size_t flush_buf(VirtIOConsolePort *port, const uint8_t *buf, size_t len)
+{
+    if (!port->hd) {
+        return 0;
+    }
+    return qemu_chr_write(port->hd, buf, len);
+}
+
+static void flush_queue(VirtIOConsolePort *port)
+{
+    VirtIOConsolePortBuffer *buf, *buf2;
+    uint8_t *outbuf;
+    size_t outlen;
+
+    while (!TAILQ_EMPTY(&port->unflushed_buffer_head)) {
+        if (!has_complete_data(port)) {
+            break;
+        }
+
+        buf = TAILQ_FIRST(&port->unflushed_buffer_head);
+        if (!buf->size) {
+            /* This is a buf that didn't get consumed as part of a
+             * previous data stream. Bad thing, shouldn't
+             * happen. But let's handle it nonetheless
+             */
+            flush_buf(port, buf->buf, buf->len);
+            TAILQ_REMOVE(&port->unflushed_buffer_head, buf, next);
+            continue;
+        }
+
+        outlen = 0;
+        outbuf = qemu_mallocz(buf->size);
+        TAILQ_FOREACH_SAFE(buf, &port->unflushed_buffer_head, next, buf2) {
+            memcpy(outbuf + outlen, buf->buf, buf->len);
+            outlen += buf->len;
+            TAILQ_REMOVE(&port->unflushed_buffer_head, buf, next);
+        }
+        flush_buf(port, outbuf, outlen);
+        qemu_free(outbuf);
+    }
+}
+
+/* Guest wants to notify us of some event */
+static void handle_control_message(VirtIOConsolePort *port,
+                                   struct virtio_console_control *cpkt)
+{
+    switch(cpkt->event) {
+    case VIRTIO_CONSOLE_PORT_OPEN:
+        port->guest_connected = cpkt->value;
+        break;
+    }
+}
+
+/* Guest wrote something to some port.
+ *
+ * Flush the data in the entire chunk that we received rather than
+ * splitting it into multiple buffers. VNC clients don't consume split
+ * buffers
+ */
 static void virtio_console_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
-    VirtIOConsole *s = to_virtio_console(vdev);
     VirtQueueElement elem;
 
     while (virtqueue_pop(vq, &elem)) {
-        ssize_t len = 0;
-        int d;
+        VirtIOConsolePort *port;
+        VirtIOConsolePortBuffer *buf;
+        struct virtio_console_header header;
+        int header_len;
 
-        for (d = 0; d < elem.out_num; d++) {
-            len += qemu_chr_write(s->chr, (uint8_t *)elem.out_sg[d].iov_base,
-                                  elem.out_sg[d].iov_len);
+        buf = qemu_mallocz(sizeof(*buf));
+
+        if (use_multiport()) {
+            header_len = sizeof(header);
+
+            memcpy(&header, elem.out_sg[0].iov_base, header_len);
+            port = get_port_from_id(header.id);
+            if (!port) {
+                qemu_free(buf);
+                goto next_buf;
+            }
+        } else {
+            header_len = 0;
+            port = get_port_from_id(0);
+        }
+
+        /* The guest always sends only one sg */
+        buf->len = elem.out_sg[0].iov_len - header_len;
+        buf->buf = qemu_mallocz(buf->len);
+        memcpy(buf->buf, elem.out_sg[0].iov_base + header_len, buf->len);
+
+        if (use_multiport() && is_internal(header.flags)) {
+            handle_control_message(port,
+                                   (struct virtio_console_control *)buf->buf);
+            qemu_free(buf->buf);
+            qemu_free(buf);
+            goto next_buf;
         }
-        virtqueue_push(vq, &elem, len);
-        virtio_notify(vdev, vq);
+	if (!use_multiport() || is_console(get_id_from_port(port))) {
+            flush_buf(port, buf->buf, buf->len);
+            qemu_free(buf->buf);
+            qemu_free(buf);
+            goto next_buf;
+        }
+        TAILQ_INSERT_TAIL(&port->unflushed_buffer_head, buf, next);
+        if (use_multiport()) {
+            /* Only the first buffer in a stream will have this
+             * set. This will help us identify the first buffer and
+             * the remaining buffers in the stream based on length
+             */
+            buf->size = header.size;
+        } else {
+            /* We always want to flush all the buffers in this case */
+            buf->size = buf->len;
+        }
+        if (!port->host_connected) {
+            goto next_buf;
+        }
+        flush_queue(port);
+    next_buf:
+        virtqueue_push(vq, &elem, elem.out_sg[0].iov_len);
     }
+    virtio_notify(vdev, vq);
 }
 
 static void virtio_console_handle_input(VirtIODevice *vdev, VirtQueue *vq)
@@ -53,73 +279,329 @@ static void virtio_console_handle_input(VirtIODevice *vdev, VirtQueue *vq)
 
 static uint32_t virtio_console_get_features(VirtIODevice *vdev)
 {
-    return 0;
+    return 1 << VIRTIO_CONSOLE_F_MULTIPORT;
 }
 
-static int vcon_can_read(void *opaque)
+static void virtio_console_set_features(VirtIODevice *vdev, uint32_t features)
 {
-    VirtIOConsole *s = (VirtIOConsole *) opaque;
+    virtio_console->guest_features = features;
+}
 
-    if (!virtio_queue_ready(s->ivq) ||
-        !(s->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
-        virtio_queue_empty(s->ivq))
-        return 0;
+/* Guest requested config info */
+static void virtio_console_get_config(VirtIODevice *vdev, uint8_t *config_data)
+{
+    memcpy(config_data, &virtcon_config, sizeof(struct virtio_console_config));
+}
 
-    /* current implementations have a page sized buffer.
-     * We fall back to a one byte per read if there is not enough room.
-     * It would be cool to have a function that returns the available byte
-     * instead of checking for a limit */
-    if (virtqueue_avail_bytes(s->ivq, TARGET_PAGE_SIZE, 0))
-        return TARGET_PAGE_SIZE;
-    if (virtqueue_avail_bytes(s->ivq, 1, 0))
-        return 1;
-    return 0;
+static void virtio_console_set_config(VirtIODevice *vdev,
+                                      const uint8_t *config_data)
+{
+    struct virtio_console_config config;
+
+    memcpy(&config, config_data, sizeof(config));
 }
 
-static void vcon_read(void *opaque, const uint8_t *buf, int size)
+static void write_to_port(VirtIOConsolePort *port,
+			  const uint8_t *buf, size_t size, uint32_t flags)
 {
-    VirtIOConsole *s = (VirtIOConsole *) opaque;
+    VirtQueue *vq = port->vcon->ivq;
     VirtQueueElement elem;
-    int offset = 0;
+    size_t offset = 0;
+    size_t len = 0;
+
+    if (!virtio_queue_ready(vq)) {
+        return;
+    }
+
+    if (!use_multiport() && is_internal(flags)) {
+        return;
+    }
 
-    /* The current kernel implementation has only one outstanding input
-     * buffer of PAGE_SIZE. Nevertheless, this function is prepared to
-     * handle multiple buffers with multiple sg element for input */
     while (offset < size) {
-        int i = 0;
-        if (!virtqueue_pop(s->ivq, &elem))
-                break;
-        while (offset < size && i < elem.in_num) {
-            int len = MIN(elem.in_sg[i].iov_len, size - offset);
-            memcpy(elem.in_sg[i].iov_base, buf + offset, len);
+        struct virtio_console_header header;
+        int i, header_len;
+
+        header_len = use_multiport() ? sizeof(header) : 0;
+
+        if (!virtqueue_pop(vq, &elem)) {
+            break;
+        }
+        if (elem.in_sg[0].iov_len < header_len) {
+            /* We can't even store our port number in this buffer. Bug? */
+            fprintf(stderr, "virtio-console: size %zd less than expected\n",
+                    elem.in_sg[0].iov_len);
+            exit(1);
+        }
+        header.id = cpu_to_le32(get_id_from_port(port));
+        header.flags = flags;
+        memcpy(elem.in_sg[0].iov_base, &header, header_len);
+
+        for (i = 0; offset < size && i < elem.in_num; i++) {
+            len = MIN(elem.in_sg[i].iov_len - header_len, size - offset);
+
+            memcpy(elem.in_sg[i].iov_base + header_len, buf + offset, len);
             offset += len;
-            i++;
+            header_len = 0;
         }
-        virtqueue_push(s->ivq, &elem, size);
+        header_len = use_multiport() ? sizeof(header) : 0;
+        virtqueue_push(vq, &elem, len + header_len);
+    }
+    virtio_notify(&port->vcon->vdev, vq);
+}
+
+static void send_control_event(VirtIOConsolePort *port,
+                               struct virtio_console_control *cpkt)
+{
+    write_to_port(port, (uint8_t *)cpkt, sizeof(*cpkt),
+                  VIRTIO_CONSOLE_ID_INTERNAL);
+}
+
+/* Readiness of the guest to accept data on a port */
+static int vcon_can_read(void *opaque)
+{
+    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
+    VirtQueue *vq = port->vcon->ivq;
+    int size, header_len;
+
+    if (use_multiport()) {
+        header_len = sizeof(struct virtio_console_header);
+    } else {
+        header_len = 0;
+    }
+
+    if (!virtio_queue_ready(vq) ||
+        !(port->vcon->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
+        virtio_queue_empty(vq)) {
+        return 0;
+    }
+    if (!port->guest_connected) {
+        return 0;
+    }
+    size = TARGET_PAGE_SIZE;
+    if (virtqueue_avail_bytes(vq, size, 0)) {
+        return size - header_len;
+    }
+    size = header_len + 1;
+    if (virtqueue_avail_bytes(vq, size, 0)) {
+        return size - header_len;
     }
-    virtio_notify(&s->vdev, s->ivq);
+    return 0;
+}
+
+/* Send data from a char device over to the guest */
+static void vcon_read(void *opaque, const uint8_t *buf, int size)
+{
+    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
+
+    write_to_port(port, buf, size, 0);
 }
 
 static void vcon_event(void *opaque, int event)
 {
-    /* we will ignore any event for the time being */
+    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
+    struct virtio_console_control cpkt;
+    bool update_needed;
+
+    cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+
+    update_needed = false;
+    switch (event) {
+    case CHR_EVENT_OPENED: {
+        cpkt.value = 1;
+        update_needed = true;
+        port->host_connected = true;
+
+        /* Flush any buffers that were pending while the chardev was
+         * disconnected
+         */
+        flush_queue(port);
+        break;
+    }
+    case CHR_EVENT_CLOSED:
+        cpkt.value = 0;
+        update_needed = true;
+        port->host_connected = false;
+        break;
+    default:
+        break;
+    }
+    if (!update_needed) {
+        return;
+    }
+    send_control_event(port, &cpkt);
+}
+
+static void virtio_console_set_port_active(uint32_t idx)
+{
+    int i = 0;
+
+    while (idx / 32) {
+        i++;
+        idx -= 32;
+    }
+    virtcon_config.ports_map[i] |= 1U << idx;
+}
+
+static bool virtio_console_is_port_active(uint32_t idx)
+{
+    int i = 0;
+
+    while (idx / 32) {
+        i++;
+        idx -= 32;
+    }
+    return virtcon_config.ports_map[i] & (1U << idx);
+}
+
+/* This function gets called from vl.c during initial options
+ * parsing as well as from the monitor to parse the options.
+ * So it's a good idea to not print out anything and just
+ * return values which can become meaningful.
+ */
+int init_virtio_console_port(int port, const char *opts)
+{
+    char dev[256];
+    const char *prot;
+    const char *idx;
+    uint32_t port_nr;
+    int j, k;
+
+    memset(dev, 0, sizeof(dev));
+    prot = strstr(opts, ",protocol=");
+    idx  = strstr(opts, ",port=");
+
+    port_nr = VIRTIO_CONSOLE_CONSOLE_PORT;
+    if (idx) {
+        port_nr = atol(idx + 6); /* skip ',port=' */
+    }
+    if (port_nr >= MAX_VIRTIO_CONSOLE_PORTS) {
+        return -ENOSPC;
+    }
+    if (virtio_console_is_port_active(port_nr)) {
+        return -EEXIST;
+    }
+
+    /* Just to maintain compatibility with other qemu options,
+     * we have the format of
+     *
+     * -virtioconsole unix:/tmp/foo,protocol=bar,port=3
+     *
+     * so to parse the 'unix:', we have to do the following
+     */
+    j = k = 0;
+    while (opts[j] && &opts[j] != prot && &opts[j] != idx) {
+        dev[k++] = opts[j++];
+    }
+
+    if (dev[0] && strncmp(dev, "none", 4)) {
+        char label[32];
+        snprintf(label, sizeof(label), "virtcon%u", port_nr);
+        virtcon_hds[port] = qemu_chr_open(label, dev, NULL);
+        if (!virtcon_hds[port]) {
+            return -EIO;
+        }
+    }
+    virtcon_idx[port] = port_nr;
+    /* The guest never opens the 'vcon device; it instead uses hvc.
+     * To ensure reads don't block in vcons_can_read on guest_connected,
+     * set it here
+     */
+    if (is_console(port_nr)) {
+        virtcon_ports[port_nr].guest_connected = true;
+    }
+    virtio_console_set_port_active(port_nr);
+
+    return 0;
+}
+
+void *virtio_console_new_port(PCIDevice *dev, uint32_t idx)
+{
+    VirtIOConsolePort *port;
+
+    port = get_port_from_id(idx);
+    port->vcon = virtio_console;
+
+    if (!port->vcon->dev && !dev) {
+        return NULL;
+    }
+    if (!port->vcon->dev) {
+        port->vcon->dev = dev;
+    }
+    /* Hot-adding ports to existing device */
+    if (!dev) {
+        dev = port->vcon->dev;
+    }
+    port->hd = qdev_init_chardev(&dev->qdev);
+    if (port->hd) {
+        qemu_chr_add_handlers(port->hd, vcon_can_read, vcon_read, vcon_event,
+                              port);
+    }
+    TAILQ_INIT(&port->unflushed_buffer_head);
+    /* Send an update to the guest about this new port added */
+    virtio_notify_config(&port->vcon->vdev);
+    return port;
 }
 
 static void virtio_console_save(QEMUFile *f, void *opaque)
 {
     VirtIOConsole *s = opaque;
+    unsigned int i;
 
+    /* The virtio device */
     virtio_save(&s->vdev, f);
+    /* The PCI device */
+    pci_device_save(s->dev, f);
+    /* The config space */
+    qemu_put_be16s(f, &virtcon_config.cols);
+    qemu_put_be16s(f, &virtcon_config.rows);
+    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
+    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
+    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
+        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
+    }
+    /* Items in struct VirtIOConsole */
+    qemu_put_be32s(f, &virtio_console->guest_features);
+    /* Items in struct VirtIOConsolePort */
+    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
+        qemu_put_byte(f, virtcon_ports[i].guest_connected);
+    }
 }
 
 static int virtio_console_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIOConsole *s = opaque;
+    unsigned int i;
+    int ret;
 
-    if (version_id != 1)
+    if (version_id > 2)
         return -EINVAL;
 
+    /* The virtio device */
     virtio_load(&s->vdev, f);
+
+    if (version_id < 2)
+        return 0;
+
+    /* The PCI device */
+    ret = pci_device_load(s->dev, f);
+    if (ret < 0) {
+        return ret;
+    }
+    /* The config space */
+    qemu_get_be16s(f, &virtcon_config.cols);
+    qemu_get_be16s(f, &virtcon_config.rows);
+    virtcon_config.max_nr_ports = cpu_to_le32(qemu_get_be32(f));
+    virtcon_config.nr_active_ports = cpu_to_le32(qemu_get_be32(f));
+    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
+        qemu_get_be32s(f, &virtcon_config.ports_map[i]);
+    }
+    /* Items in struct VirtIOConsole */
+    qemu_get_be32s(f, &virtio_console->guest_features);
+    /* Items in struct VirtIOConsolePort */
+    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
+        virtcon_ports[i].guest_connected = qemu_get_byte(f);
+    }
+
     return 0;
 }
 
@@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
     VirtIOConsole *s;
     s = (VirtIOConsole *)virtio_common_init("virtio-console",
                                             VIRTIO_ID_CONSOLE,
-                                            0, sizeof(VirtIOConsole));
+                                            sizeof(struct virtio_console_config),
+                                            sizeof(VirtIOConsole));
     if (s == NULL)
         return NULL;
 
+    virtio_console = s;
     s->vdev.get_features = virtio_console_get_features;
+    s->vdev.set_features = virtio_console_set_features;
+    s->vdev.get_config = virtio_console_get_config;
+    s->vdev.set_config = virtio_console_set_config;
 
+    /* Add queue for host to guest transfers */
     s->ivq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_input);
-    s->dvq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_output);
+    /* Add queue for guest to host transfers */
+    s->ovq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_output);
+
+    s->ports = virtcon_ports;
+    s->config = &virtcon_config;
 
-    s->chr = qdev_init_chardev(dev);
-    qemu_chr_add_handlers(s->chr, vcon_can_read, vcon_read, vcon_event, s);
+    register_savevm("virtio-console", -1, 2, virtio_console_save, virtio_console_load, s);
 
-    register_savevm("virtio-console", -1, 1, virtio_console_save, virtio_console_load, s);
+    virtcon_config.max_nr_ports = cpu_to_le32(MAX_VIRTIO_CONSOLE_PORTS);
+    virtcon_config.nr_active_ports = cpu_to_le32(virtcon_nr_ports);
 
     return &s->vdev;
 }
diff --git a/hw/virtio-console.h b/hw/virtio-console.h
index 84d0717..18b3a96 100644
--- a/hw/virtio-console.h
+++ b/hw/virtio-console.h
@@ -2,9 +2,11 @@
  * Virtio Console Support
  *
  * Copyright IBM, Corp. 2008
+ * Copyright Red Hat, Inc. 2009
  *
  * Authors:
  *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
+ *  Amit Shah <amit.shah@redhat.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -13,7 +15,57 @@
 #ifndef _QEMU_VIRTIO_CONSOLE_H
 #define _QEMU_VIRTIO_CONSOLE_H
 
+#include "sysemu.h"
+
+/* Interface shared between the guest kernel and qemu */
+
 /* The ID for virtio console */
 #define VIRTIO_ID_CONSOLE 3
 
+/* Invalid port number */
+#define VIRTIO_CONSOLE_BAD_ID		(~(uint32_t)0)
+
+/* Port number at which the console is spawned */
+#define VIRTIO_CONSOLE_CONSOLE_PORT	0
+#define VIRTIO_CONSOLE_CONSOLE2_PORT	1
+
+/* Features supported */
+#define VIRTIO_CONSOLE_F_MULTIPORT	1
+
+struct virtio_console_config
+{
+    /* These two fields are used by VIRTIO_CONSOLE_F_SIZE which
+     * isn't implemented here yet
+     */
+    uint16_t cols;
+    uint16_t rows;
+
+    uint32_t max_nr_ports;
+    uint32_t nr_active_ports;
+    uint32_t ports_map[(MAX_VIRTIO_CONSOLE_PORTS + 31) / 32];
+} __attribute__((packed));
+
+struct virtio_console_control
+{
+    uint16_t event;
+    uint16_t value;
+};
+
+struct virtio_console_header {
+    uint32_t id; /* Port id */
+    uint32_t flags; /* Some message between host and guest */
+    uint32_t size; /* Size that's sent with the first buffer of each stream */
+} __attribute__((packed));
+
+/* Messages between host and guest */
+#define VIRTIO_CONSOLE_ID_INTERNAL	(1 << 0)
+
+/* Some events for the internal messages (control packets) */
+#define VIRTIO_CONSOLE_PORT_OPEN	0
+
+
+/* In-qemu interface */
+void virtio_console_monitor_command(Monitor *mon,
+				    const char *command, const char *param);
+
 #endif
diff --git a/monitor.c b/monitor.c
index f2e0455..c909acf 100644
--- a/monitor.c
+++ b/monitor.c
@@ -45,6 +45,7 @@
 #include "kvm.h"
 #include "acl.h"
 #include "exec-all.h"
+#include "hw/virtio-console.h"
 
 #include "qemu-kvm.h"
 
@@ -1769,6 +1770,12 @@ int monitor_get_fd(Monitor *mon, const char *fdname)
     return -1;
 }
 
+static void do_virtio_console_action(Monitor *mon,
+                                     const char *command, const char *param)
+{
+    virtio_console_monitor_command(mon, command, param);
+}
+
 static const mon_cmd_t mon_cmds[] = {
 #include "qemu-monitor.h"
     { NULL, NULL, },
diff --git a/qemu-monitor.hx b/qemu-monitor.hx
index c193a1e..905cb4c 100644
--- a/qemu-monitor.hx
+++ b/qemu-monitor.hx
@@ -572,6 +572,16 @@ STEXI
 Change watchdog action.
 ETEXI
 
+    { "virtio-console", "ss?", do_virtio_console_action,
+      "<command> [<parameters>]\n",
+      "virtio-serial write port=3,key=get,value=clipboard\n"
+      "virtio-serial add_port\n"
+      "virtio-serial add_port port=6,name=foo,protocol=keyvalue\n" },
+STEXI
+@item virtio-console
+Hot-add ports or send data to virtio-console port
+ETEXI
+
     { "acl_show", "s", do_acl_show, "aclname",
       "list rules in the access control list" },
 STEXI
diff --git a/qemu-options.hx b/qemu-options.hx
index ade1663..a2a7629 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1594,7 +1594,7 @@ ETEXI
 
 DEF("virtioconsole", HAS_ARG, QEMU_OPTION_virtiocon, \
     "-virtioconsole c\n" \
-    "                set virtio console\n")
+    "                define virtio console\n")
 STEXI
 @item -virtioconsole @var{c}
 Set virtio console.
diff --git a/sysemu.h b/sysemu.h
index 8a2874a..109b8e7 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -2,6 +2,7 @@
 #define SYSEMU_H
 /* Misc. things related to the system emulator.  */
 
+#include <stdbool.h>
 #include "qemu-common.h"
 #include "qemu-option.h"
 #include "sys-queue.h"
@@ -230,9 +231,14 @@ extern CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
 
 /* virtio consoles */
 
-#define MAX_VIRTIO_CONSOLES 1
+#define MAX_VIRTIO_CONSOLE_PORTS 64
+#define VIRTIO_CONSOLE_PROTO_MAX_LEN 30
 
-extern CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
+extern CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLE_PORTS];
+extern uint32_t virtcon_idx[MAX_VIRTIO_CONSOLE_PORTS];
+extern int virtcon_nr_ports;
+extern int init_virtio_console_port(int port, const char *opts);
+extern void *virtio_console_new_port(PCIDevice *dev, uint32_t idx);
 
 #define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
 
diff --git a/vl.c b/vl.c
index 5d2f359..54ea583 100644
--- a/vl.c
+++ b/vl.c
@@ -211,7 +211,10 @@ static int no_frame = 0;
 int no_quit = 0;
 CharDriverState *serial_hds[MAX_SERIAL_PORTS];
 CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
-CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
+CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLE_PORTS];
+char virtcon_prot[MAX_VIRTIO_CONSOLE_PORTS][VIRTIO_CONSOLE_PROTO_MAX_LEN];
+uint32_t virtcon_idx[MAX_VIRTIO_CONSOLE_PORTS];
+int virtcon_nr_ports;
 #ifdef TARGET_I386
 int win2k_install_hack = 0;
 int rtc_td_hack = 0;
@@ -4843,8 +4846,7 @@ int main(int argc, char **argv, char **envp)
     int serial_device_index;
     const char *parallel_devices[MAX_PARALLEL_PORTS];
     int parallel_device_index;
-    const char *virtio_consoles[MAX_VIRTIO_CONSOLES];
-    int virtio_console_index;
+    const char *virtio_consoles[MAX_VIRTIO_CONSOLE_PORTS];
     const char *loadvm = NULL;
     QEMUMachine *machine;
     const char *cpu_model;
@@ -4918,9 +4920,9 @@ int main(int argc, char **argv, char **envp)
         parallel_devices[i] = NULL;
     parallel_device_index = 0;
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++)
+    for(i = 0; i < MAX_VIRTIO_CONSOLE_PORTS; i++)
         virtio_consoles[i] = NULL;
-    virtio_console_index = 0;
+    virtcon_nr_ports = 0;
 
     for (i = 0; i < MAX_NODES; i++) {
         node_mem[i] = 0;
@@ -5360,12 +5362,12 @@ int main(int argc, char **argv, char **envp)
                 }
                 break;
             case QEMU_OPTION_virtiocon:
-                if (virtio_console_index >= MAX_VIRTIO_CONSOLES) {
+                if (virtcon_nr_ports >= MAX_VIRTIO_CONSOLE_PORTS) {
                     fprintf(stderr, "qemu: too many virtio consoles\n");
                     exit(1);
                 }
-                virtio_consoles[virtio_console_index] = optarg;
-                virtio_console_index++;
+                virtio_consoles[virtcon_nr_ports] = optarg;
+                virtcon_nr_ports++;
                 break;
             case QEMU_OPTION_parallel:
                 if (parallel_device_index >= MAX_PARALLEL_PORTS) {
@@ -5960,17 +5962,13 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
-        const char *devname = virtio_consoles[i];
-        if (devname && strcmp(devname, "none")) {
-            char label[32];
-            snprintf(label, sizeof(label), "virtcon%d", i);
-            virtcon_hds[i] = qemu_chr_open(label, devname, NULL);
-            if (!virtcon_hds[i]) {
-                fprintf(stderr, "qemu: could not open virtio console '%s'\n",
-                        devname);
-                exit(1);
-            }
+    for (i = 0; i < virtcon_nr_ports; i++) {
+        int ret;
+
+        ret = init_virtio_console_port(i, virtio_consoles[i]);
+        if (ret < 0) {
+            fprintf(stderr, "qemu: could not init virtio console port at \"%s\"\n", virtio_consoles[i]);
+            exit(1);
         }
     }
 
@@ -6085,11 +6083,12 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
+    for(i = 0; i < MAX_VIRTIO_CONSOLE_PORTS; i++) {
         const char *devname = virtio_consoles[i];
         if (virtcon_hds[i] && devname) {
             if (strstart(devname, "vc", 0))
-                qemu_chr_printf(virtcon_hds[i], "virtio console%d\r\n", i);
+                qemu_chr_printf(virtcon_hds[i], "virtio console%d\r\n",
+                                virtcon_idx[i]);
         }
     }
 
-- 
1.6.2.5

Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Juan Quintela]

Amit Shah <amit.shah@redhat.com> wrote:
> This interface extends the virtio-console device to handle
> multiple ports that present a char device from which bits can
> be sent and read.
>
> Sample uses for such a device can be obtaining info from the
> guest like the file systems used, apps installed, etc. for
> offline usage and logged-in users, clipboard copy-paste, etc.
> for online usage.
>
> Each port is to be assigned a unique function, for example, the
> first 4 ports may be reserved for libvirt usage, the next 4 for
> generic streaming data and so on. This port-function mapping
> isn't finalised yet.
>
> For requirements, use-cases and some history see
>
>     http://www.linux-kvm.org/page/VMchannel_Requirements
>
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
>  hw/pc.c             |   16 +-
>  hw/virtio-console.c |  594 ++++++++++++++++++++++++++++++++++++++++++++++-----
>  hw/virtio-console.h |   52 +++++
>  monitor.c           |    7 +
>  qemu-monitor.hx     |   10 +
>  qemu-options.hx     |    2 +-
>  sysemu.h            |   10 +-
>  vl.c                |   41 ++--
>  8 files changed, 652 insertions(+), 80 deletions(-)
>
> diff --git a/hw/pc.c b/hw/pc.c
> index 503feb0..0e60ecc 100644
> --- a/hw/pc.c
> +++ b/hw/pc.c
> @@ -1462,11 +1462,17 @@ static void pc_init1(ram_addr_t ram_size,
>      }
>  
>      /* Add virtio console devices */
> -    if (pci_enabled) {
> -        for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
> -            if (virtcon_hds[i]) {
> -                pci_create_simple(pci_bus, -1, "virtio-console-pci");
> -            }
> +    if (pci_enabled && virtcon_nr_ports) {
> +        void *dev;
> +
> +        dev = pci_create_simple(pci_bus, -1, "virtio-console-pci");
> +        if (!dev) {
> +            fprintf(stderr, "qemu: could not create virtio console pci device\n");
> +            exit(1);
> +        }
> +
> +        for (i = 0; i < virtcon_nr_ports; i++) {
> +                virtio_console_new_port(dev, virtcon_idx[i]);
>          }
>      }
>  
> diff --git a/hw/virtio-console.c b/hw/virtio-console.c
> index 663c8b9..da590d2 100644
> --- a/hw/virtio-console.c
> +++ b/hw/virtio-console.c
> @@ -2,9 +2,11 @@
>   * Virtio Console Device
>   *
>   * Copyright IBM, Corp. 2008
> + * Copyright Red Hat, Inc. 2009
>   *
>   * Authors:
>   *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
> + *  Amit Shah <amit.shah@redhat.com>
>   *
>   * This work is licensed under the terms of the GNU GPL, version 2.  See
>   * the COPYING file in the top-level directory.
> @@ -12,39 +14,263 @@
>   */
>  
>  #include "hw.h"
> +#include "monitor.h"
> +#include "pci.h"
> +#include "sys-queue.h"
>  #include "qemu-char.h"
>  #include "virtio.h"
>  #include "virtio-console.h"
>  
> -
>  typedef struct VirtIOConsole
>  {
>      VirtIODevice vdev;
> -    VirtQueue *ivq, *dvq;
> -    CharDriverState *chr;
> +    PCIDevice *dev;

Why do you need dev here?  VirtIODevice already have hidded somewhere
a PCIDevice (hidded is a good defenition).
virtio-blk and virtio-net are able to work with that pci device.

> +/* Readiness of the guest to accept data on a port */
> +static int vcon_can_read(void *opaque)
> +{
> +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;

Cast is not needed here.

> +/* Send data from a char device over to the guest */
> +static void vcon_read(void *opaque, const uint8_t *buf, int size)
> +{
> +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;

Cast is not needed here. (there are still more instances on the file)


> +        return;
> +    }
> +    send_control_event(port, &cpkt);
> +}
> +
> +static void virtio_console_set_port_active(uint32_t idx)
> +{
> +    int i = 0;
> +
> +    while (idx / 32) {
> +        i++;
> +        idx -= 32;
> +    }

It is just me, or you are doing a division + modulus in a very strange way?

   i = idx / 32;
   idx = idx % 32;

???

> +    virtcon_config.ports_map[i] |= 1U << idx;
> +}
> +
> +static bool virtio_console_is_port_active(uint32_t idx)
> +{
> +    int i = 0;
> +
> +    while (idx / 32) {
> +        i++;
> +        idx -= 32;
> +    }

Same comment about division.

>  static void virtio_console_save(QEMUFile *f, void *opaque)
>  {
>      VirtIOConsole *s = opaque;
> +    unsigned int i;
>  
> +    /* The virtio device */
>      virtio_save(&s->vdev, f);
> +    /* The PCI device */
> +    pci_device_save(s->dev, f);

If you don't use pci here, virtio_save() should save your pci stuff
here.  See the ->load_config() stuff.

Yeap, it can confuse anybody.

For the new table based vmstate, fields need to live in an struct, in
this case VirtIOConsole.

Can you move virtcon_config and virtcon_ports to VirtIOConsole.

> +    /* The config space */
> +    qemu_put_be16s(f, &virtcon_config.cols);
> +    qemu_put_be16s(f, &virtcon_config.rows);

> +    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
> +    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
> +    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
> +        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> +    }

Don't even try to save a couple of bytes, please.

for (i = 0; i <  (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
    qemu_put_be32s(f, &virtcon_config.ports_map[i]);
}

Same for load, please.  Makes the translation to table based way easier.

> +    /* Items in struct VirtIOConsole */
> +    qemu_put_be32s(f, &virtio_console->guest_features);

here you mean s->guest_features, right?

> +    /* Items in struct VirtIOConsolePort */
> +    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
> +        qemu_put_byte(f, virtcon_ports[i].guest_connected);
> +    }

If you want to optimize saving of this field, it is possible that it is
a better idea to create another bitmap for it.  What do you think?

I can't see VMState adding support for bools any time soon, but arrays
of bool is a possibility.

> @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
>      VirtIOConsole *s;
>      s = (VirtIOConsole *)virtio_common_init("virtio-console",
>                                              VIRTIO_ID_CONSOLE,
> -                                            0, sizeof(VirtIOConsole));
> +                                            sizeof(struct virtio_console_config),
> +                                            sizeof(VirtIOConsole));

Here, you mean:

VirtIODevice *d = virtio_common_init(....);
VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);

:)

Creation of VirtIODevice *d is not necesary, I found it easier to
understand  but it is up to you.

>      if (s == NULL)
>          return NULL;
>  

Once you are there, virtio_common_init() can't return NULL, fix it please.

>  
> -#define MAX_VIRTIO_CONSOLES 1
> +#define MAX_VIRTIO_CONSOLE_PORTS 64

Require that this number is a multiple of 32, and you can simplify all
the (foo + 31/32) staff.


Later, Juan.

Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

Hi Juan,

On (Thu) Sep 03 2009 [16:06:54], Juan Quintela wrote:
> > diff --git a/hw/virtio-console.c b/hw/virtio-console.c
> > index 663c8b9..da590d2 100644
> > --- a/hw/virtio-console.c
> > +++ b/hw/virtio-console.c
> >  
> >  #include "hw.h"
> > +#include "monitor.h"
> > +#include "pci.h"
> > +#include "sys-queue.h"
> >  #include "qemu-char.h"
> >  #include "virtio.h"
> >  #include "virtio-console.h"
> >  
> > -
> >  typedef struct VirtIOConsole
> >  {
> >      VirtIODevice vdev;
> > -    VirtQueue *ivq, *dvq;
> > -    CharDriverState *chr;
> > +    PCIDevice *dev;
> 
> Why do you need dev here?  VirtIODevice already have hidded somewhere
> a PCIDevice (hidded is a good defenition).
> virtio-blk and virtio-net are able to work with that pci device.

Let me check that; I need pci device while initialising a new port (and
it's slightly different when done at init and when done at hot-add
time).

> > +/* Readiness of the guest to accept data on a port */
> > +static int vcon_can_read(void *opaque)
> > +{
> > +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
> 
> Cast is not needed here.

This is original code that I've not modified (just moved around).

But you're right; I could do that in this patch itself.

> > +static void virtio_console_set_port_active(uint32_t idx)
> > +{
> > +    int i = 0;
> > +
> > +    while (idx / 32) {
> > +        i++;
> > +        idx -= 32;
> > +    }
> 
> It is just me, or you are doing a division + modulus in a very strange way?
> 
>    i = idx / 32;
>    idx = idx % 32;
> 
> ???



> >  static void virtio_console_save(QEMUFile *f, void *opaque)
> >  {
> >      VirtIOConsole *s = opaque;
> > +    unsigned int i;
> >  
> > +    /* The virtio device */
> >      virtio_save(&s->vdev, f);
> > +    /* The PCI device */
> > +    pci_device_save(s->dev, f);
> 
> If you don't use pci here, virtio_save() should save your pci stuff
> here.  See the ->load_config() stuff.
> 
> Yeap, it can confuse anybody.

Actually no. Since virtio rides on top of pci, I'd expect virtio_save to
save pci state too :-)

I'll check this too.

> For the new table based vmstate, fields need to live in an struct, in
> this case VirtIOConsole.
> 
> Can you move virtcon_config and virtcon_ports to VirtIOConsole.

In that case VirtIOConsole has to become a static (instead of being
allocated via the call to virtio_common_init. Doable.

> > +    /* The config space */
> > +    qemu_put_be16s(f, &virtcon_config.cols);
> > +    qemu_put_be16s(f, &virtcon_config.rows);
> 
> > +    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
> > +    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
> > +    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
> > +        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> > +    }
> 
> Don't even try to save a couple of bytes, please.

Sorry, don't understand this.

> 
> for (i = 0; i <  (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
>     qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> }
> 
> Same for load, please.  Makes the translation to table based way easier.

OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
correct?

I do it this way because we could be migrated from a host that supports
64 max ports to a host that supports 128 max ports and then back to the
one that supports 64 max ports. :-)

> > +    /* Items in struct VirtIOConsole */
> > +    qemu_put_be32s(f, &virtio_console->guest_features);
> 
> here you mean s->guest_features, right?

Right!

> > +    /* Items in struct VirtIOConsolePort */
> > +    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
> > +        qemu_put_byte(f, virtcon_ports[i].guest_connected);
> > +    }
> 
> If you want to optimize saving of this field, it is possible that it is
> a better idea to create another bitmap for it.  What do you think?

Yes, I wanted to do that as well. The same functions that compute the
modulo/division earlier can give us this thing as well. But it'll only
be used for loadvm/savevm. I expect the bool to continue to reside in
this struct for normal operation.

> I can't see VMState adding support for bools any time soon, but arrays
> of bool is a possibility.

Consider the RFE filed :-)

> > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
> >      VirtIOConsole *s;
> >      s = (VirtIOConsole *)virtio_common_init("virtio-console",
> >                                              VIRTIO_ID_CONSOLE,
> > -                                            0, sizeof(VirtIOConsole));
> > +                                            sizeof(struct virtio_console_config),
> > +                                            sizeof(VirtIOConsole));
> 
> Here, you mean:
> 
> VirtIODevice *d = virtio_common_init(....);
> VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
> 
> :)

Again original code, not my contributions :-)

> Creation of VirtIODevice *d is not necesary, I found it easier to
> understand  but it is up to you.

For virtio-serial, I statically allocated VirtIOSerial and had a vdev
pointer inside it which virtio_common_init gave me. I can do the same
here.

> >      if (s == NULL)
> >          return NULL;
> >  
> 
> Once you are there, virtio_common_init() can't return NULL, fix it please.

Original code. But I will take it.

> > -#define MAX_VIRTIO_CONSOLES 1
> > +#define MAX_VIRTIO_CONSOLE_PORTS 64
> 
> Require that this number is a multiple of 32, and you can simplify all
> the (foo + 31/32) staff.

Sure, but it's better to be careful in a couple of places just because
we can be. Does (foo+31)/32 make it very difficult to read?

		Amit
-- 
http://log.amitshah.net/

[Qemu-devel] Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

Hi Juan,

On (Thu) Sep 03 2009 [16:06:54], Juan Quintela wrote:
> > diff --git a/hw/virtio-console.c b/hw/virtio-console.c
> > index 663c8b9..da590d2 100644
> > --- a/hw/virtio-console.c
> > +++ b/hw/virtio-console.c
> >  
> >  #include "hw.h"
> > +#include "monitor.h"
> > +#include "pci.h"
> > +#include "sys-queue.h"
> >  #include "qemu-char.h"
> >  #include "virtio.h"
> >  #include "virtio-console.h"
> >  
> > -
> >  typedef struct VirtIOConsole
> >  {
> >      VirtIODevice vdev;
> > -    VirtQueue *ivq, *dvq;
> > -    CharDriverState *chr;
> > +    PCIDevice *dev;
> 
> Why do you need dev here?  VirtIODevice already have hidded somewhere
> a PCIDevice (hidded is a good defenition).
> virtio-blk and virtio-net are able to work with that pci device.

Let me check that; I need pci device while initialising a new port (and
it's slightly different when done at init and when done at hot-add
time).

> > +/* Readiness of the guest to accept data on a port */
> > +static int vcon_can_read(void *opaque)
> > +{
> > +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
> 
> Cast is not needed here.

This is original code that I've not modified (just moved around).

But you're right; I could do that in this patch itself.

> > +static void virtio_console_set_port_active(uint32_t idx)
> > +{
> > +    int i = 0;
> > +
> > +    while (idx / 32) {
> > +        i++;
> > +        idx -= 32;
> > +    }
> 
> It is just me, or you are doing a division + modulus in a very strange way?
> 
>    i = idx / 32;
>    idx = idx % 32;
> 
> ???



> >  static void virtio_console_save(QEMUFile *f, void *opaque)
> >  {
> >      VirtIOConsole *s = opaque;
> > +    unsigned int i;
> >  
> > +    /* The virtio device */
> >      virtio_save(&s->vdev, f);
> > +    /* The PCI device */
> > +    pci_device_save(s->dev, f);
> 
> If you don't use pci here, virtio_save() should save your pci stuff
> here.  See the ->load_config() stuff.
> 
> Yeap, it can confuse anybody.

Actually no. Since virtio rides on top of pci, I'd expect virtio_save to
save pci state too :-)

I'll check this too.

> For the new table based vmstate, fields need to live in an struct, in
> this case VirtIOConsole.
> 
> Can you move virtcon_config and virtcon_ports to VirtIOConsole.

In that case VirtIOConsole has to become a static (instead of being
allocated via the call to virtio_common_init. Doable.

> > +    /* The config space */
> > +    qemu_put_be16s(f, &virtcon_config.cols);
> > +    qemu_put_be16s(f, &virtcon_config.rows);
> 
> > +    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
> > +    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
> > +    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
> > +        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> > +    }
> 
> Don't even try to save a couple of bytes, please.

Sorry, don't understand this.

> 
> for (i = 0; i <  (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
>     qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> }
> 
> Same for load, please.  Makes the translation to table based way easier.

OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
correct?

I do it this way because we could be migrated from a host that supports
64 max ports to a host that supports 128 max ports and then back to the
one that supports 64 max ports. :-)

> > +    /* Items in struct VirtIOConsole */
> > +    qemu_put_be32s(f, &virtio_console->guest_features);
> 
> here you mean s->guest_features, right?

Right!

> > +    /* Items in struct VirtIOConsolePort */
> > +    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
> > +        qemu_put_byte(f, virtcon_ports[i].guest_connected);
> > +    }
> 
> If you want to optimize saving of this field, it is possible that it is
> a better idea to create another bitmap for it.  What do you think?

Yes, I wanted to do that as well. The same functions that compute the
modulo/division earlier can give us this thing as well. But it'll only
be used for loadvm/savevm. I expect the bool to continue to reside in
this struct for normal operation.

> I can't see VMState adding support for bools any time soon, but arrays
> of bool is a possibility.

Consider the RFE filed :-)

> > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
> >      VirtIOConsole *s;
> >      s = (VirtIOConsole *)virtio_common_init("virtio-console",
> >                                              VIRTIO_ID_CONSOLE,
> > -                                            0, sizeof(VirtIOConsole));
> > +                                            sizeof(struct virtio_console_config),
> > +                                            sizeof(VirtIOConsole));
> 
> Here, you mean:
> 
> VirtIODevice *d = virtio_common_init(....);
> VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
> 
> :)

Again original code, not my contributions :-)

> Creation of VirtIODevice *d is not necesary, I found it easier to
> understand  but it is up to you.

For virtio-serial, I statically allocated VirtIOSerial and had a vdev
pointer inside it which virtio_common_init gave me. I can do the same
here.

> >      if (s == NULL)
> >          return NULL;
> >  
> 
> Once you are there, virtio_common_init() can't return NULL, fix it please.

Original code. But I will take it.

> > -#define MAX_VIRTIO_CONSOLES 1
> > +#define MAX_VIRTIO_CONSOLE_PORTS 64
> 
> Require that this number is a multiple of 32, and you can simplify all
> the (foo + 31/32) staff.

Sure, but it's better to be careful in a couple of places just because
we can be. Does (foo+31)/32 make it very difficult to read?

		Amit
-- 
http://log.amitshah.net/

Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

Hi Juan,

On (Thu) Sep 03 2009 [16:06:54], Juan Quintela wrote:
> > diff --git a/hw/virtio-console.c b/hw/virtio-console.c
> > index 663c8b9..da590d2 100644
> > --- a/hw/virtio-console.c
> > +++ b/hw/virtio-console.c
> >  
> >  #include "hw.h"
> > +#include "monitor.h"
> > +#include "pci.h"
> > +#include "sys-queue.h"
> >  #include "qemu-char.h"
> >  #include "virtio.h"
> >  #include "virtio-console.h"
> >  
> > -
> >  typedef struct VirtIOConsole
> >  {
> >      VirtIODevice vdev;
> > -    VirtQueue *ivq, *dvq;
> > -    CharDriverState *chr;
> > +    PCIDevice *dev;
> 
> Why do you need dev here?  VirtIODevice already have hidded somewhere
> a PCIDevice (hidded is a good defenition).
> virtio-blk and virtio-net are able to work with that pci device.

Let me check that; I need pci device while initialising a new port (and
it's slightly different when done at init and when done at hot-add
time).

> > +/* Readiness of the guest to accept data on a port */
> > +static int vcon_can_read(void *opaque)
> > +{
> > +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
> 
> Cast is not needed here.

This is original code that I've not modified (just moved around).

But you're right; I could do that in this patch itself.

> > +static void virtio_console_set_port_active(uint32_t idx)
> > +{
> > +    int i = 0;
> > +
> > +    while (idx / 32) {
> > +        i++;
> > +        idx -= 32;
> > +    }
> 
> It is just me, or you are doing a division + modulus in a very strange way?
> 
>    i = idx / 32;
>    idx = idx % 32;
> 
> ???



> >  static void virtio_console_save(QEMUFile *f, void *opaque)
> >  {
> >      VirtIOConsole *s = opaque;
> > +    unsigned int i;
> >  
> > +    /* The virtio device */
> >      virtio_save(&s->vdev, f);
> > +    /* The PCI device */
> > +    pci_device_save(s->dev, f);
> 
> If you don't use pci here, virtio_save() should save your pci stuff
> here.  See the ->load_config() stuff.
> 
> Yeap, it can confuse anybody.

Actually no. Since virtio rides on top of pci, I'd expect virtio_save to
save pci state too :-)

I'll check this too.

> For the new table based vmstate, fields need to live in an struct, in
> this case VirtIOConsole.
> 
> Can you move virtcon_config and virtcon_ports to VirtIOConsole.

In that case VirtIOConsole has to become a static (instead of being
allocated via the call to virtio_common_init. Doable.

> > +    /* The config space */
> > +    qemu_put_be16s(f, &virtcon_config.cols);
> > +    qemu_put_be16s(f, &virtcon_config.rows);
> 
> > +    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
> > +    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
> > +    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
> > +        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> > +    }
> 
> Don't even try to save a couple of bytes, please.

Sorry, don't understand this.

> 
> for (i = 0; i <  (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
>     qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> }
> 
> Same for load, please.  Makes the translation to table based way easier.

OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
correct?

I do it this way because we could be migrated from a host that supports
64 max ports to a host that supports 128 max ports and then back to the
one that supports 64 max ports. :-)

> > +    /* Items in struct VirtIOConsole */
> > +    qemu_put_be32s(f, &virtio_console->guest_features);
> 
> here you mean s->guest_features, right?

Right!

> > +    /* Items in struct VirtIOConsolePort */
> > +    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
> > +        qemu_put_byte(f, virtcon_ports[i].guest_connected);
> > +    }
> 
> If you want to optimize saving of this field, it is possible that it is
> a better idea to create another bitmap for it.  What do you think?

Yes, I wanted to do that as well. The same functions that compute the
modulo/division earlier can give us this thing as well. But it'll only
be used for loadvm/savevm. I expect the bool to continue to reside in
this struct for normal operation.

> I can't see VMState adding support for bools any time soon, but arrays
> of bool is a possibility.

Consider the RFE filed :-)

> > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
> >      VirtIOConsole *s;
> >      s = (VirtIOConsole *)virtio_common_init("virtio-console",
> >                                              VIRTIO_ID_CONSOLE,
> > -                                            0, sizeof(VirtIOConsole));
> > +                                            sizeof(struct virtio_console_config),
> > +                                            sizeof(VirtIOConsole));
> 
> Here, you mean:
> 
> VirtIODevice *d = virtio_common_init(....);
> VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
> 
> :)

Again original code, not my contributions :-)

> Creation of VirtIODevice *d is not necesary, I found it easier to
> understand  but it is up to you.

For virtio-serial, I statically allocated VirtIOSerial and had a vdev
pointer inside it which virtio_common_init gave me. I can do the same
here.

> >      if (s == NULL)
> >          return NULL;
> >  
> 
> Once you are there, virtio_common_init() can't return NULL, fix it please.

Original code. But I will take it.

> > -#define MAX_VIRTIO_CONSOLES 1
> > +#define MAX_VIRTIO_CONSOLE_PORTS 64
> 
> Require that this number is a multiple of 32, and you can simplify all
> the (foo + 31/32) staff.

Sure, but it's better to be careful in a couple of places just because
we can be. Does (foo+31)/32 make it very difficult to read?

		Amit
-- 
http://log.amitshah.net/

Re: [Qemu-devel] Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

On (Thu) Sep 03 2009 [19:56:05], Amit Shah wrote:
> Hi Juan,
> 
> On (Thu) Sep 03 2009 [16:06:54], Juan Quintela wrote:
> > > diff --git a/hw/virtio-console.c b/hw/virtio-console.c
> > > index 663c8b9..da590d2 100644
> > > --- a/hw/virtio-console.c
> > > +++ b/hw/virtio-console.c
> > >  
> > >  #include "hw.h"
> > > +#include "monitor.h"
> > > +#include "pci.h"
> > > +#include "sys-queue.h"
> > >  #include "qemu-char.h"
> > >  #include "virtio.h"
> > >  #include "virtio-console.h"
> > >  
> > > -
> > >  typedef struct VirtIOConsole
> > >  {
> > >      VirtIODevice vdev;
> > > -    VirtQueue *ivq, *dvq;
> > > -    CharDriverState *chr;
> > > +    PCIDevice *dev;
> > 
> > Why do you need dev here?  VirtIODevice already have hidded somewhere
> > a PCIDevice (hidded is a good defenition).
> > virtio-blk and virtio-net are able to work with that pci device.
> 
> Let me check that; I need pci device while initialising a new port (and
> it's slightly different when done at init and when done at hot-add
> time).
> 
> > > +/* Readiness of the guest to accept data on a port */
> > > +static int vcon_can_read(void *opaque)
> > > +{
> > > +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
> > 
> > Cast is not needed here.
> 
> This is original code that I've not modified (just moved around).
> 
> But you're right; I could do that in this patch itself.
> 
> > > +static void virtio_console_set_port_active(uint32_t idx)
> > > +{
> > > +    int i = 0;
> > > +
> > > +    while (idx / 32) {
> > > +        i++;
> > > +        idx -= 32;
> > > +    }
> > 
> > It is just me, or you are doing a division + modulus in a very strange way?
> > 
> >    i = idx / 32;
> >    idx = idx % 32;
> > 
> > ???

Er, sorry I left this out.

That won't work for MAX_PORTS > 32.

But I guess I can just do

i = idx / MAX_VIRTIO_CONSOLE_PORTS;
idx = idx % MAX_VIRTIO_CONSOLE_PORTS;

> > >  static void virtio_console_save(QEMUFile *f, void *opaque)
> > >  {
> > >      VirtIOConsole *s = opaque;
> > > +    unsigned int i;
> > >  
> > > +    /* The virtio device */
> > >      virtio_save(&s->vdev, f);
> > > +    /* The PCI device */
> > > +    pci_device_save(s->dev, f);
> > 
> > If you don't use pci here, virtio_save() should save your pci stuff
> > here.  See the ->load_config() stuff.
> > 
> > Yeap, it can confuse anybody.
> 
> Actually no. Since virtio rides on top of pci, I'd expect virtio_save to
> save pci state too :-)
> 
> I'll check this too.
> 
> > For the new table based vmstate, fields need to live in an struct, in
> > this case VirtIOConsole.
> > 
> > Can you move virtcon_config and virtcon_ports to VirtIOConsole.
> 
> In that case VirtIOConsole has to become a static (instead of being
> allocated via the call to virtio_common_init. Doable.
> 
> > > +    /* The config space */
> > > +    qemu_put_be16s(f, &virtcon_config.cols);
> > > +    qemu_put_be16s(f, &virtcon_config.rows);
> > 
> > > +    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
> > > +    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
> > > +    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
> > > +        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> > > +    }
> > 
> > Don't even try to save a couple of bytes, please.
> 
> Sorry, don't understand this.
> 
> > 
> > for (i = 0; i <  (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
> >     qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> > }
> > 
> > Same for load, please.  Makes the translation to table based way easier.
> 
> OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
> correct?
> 
> I do it this way because we could be migrated from a host that supports
> 64 max ports to a host that supports 128 max ports and then back to the
> one that supports 64 max ports. :-)
> 
> > > +    /* Items in struct VirtIOConsole */
> > > +    qemu_put_be32s(f, &virtio_console->guest_features);
> > 
> > here you mean s->guest_features, right?
> 
> Right!
> 
> > > +    /* Items in struct VirtIOConsolePort */
> > > +    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
> > > +        qemu_put_byte(f, virtcon_ports[i].guest_connected);
> > > +    }
> > 
> > If you want to optimize saving of this field, it is possible that it is
> > a better idea to create another bitmap for it.  What do you think?
> 
> Yes, I wanted to do that as well. The same functions that compute the
> modulo/division earlier can give us this thing as well. But it'll only
> be used for loadvm/savevm. I expect the bool to continue to reside in
> this struct for normal operation.
> 
> > I can't see VMState adding support for bools any time soon, but arrays
> > of bool is a possibility.
> 
> Consider the RFE filed :-)
> 
> > > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
> > >      VirtIOConsole *s;
> > >      s = (VirtIOConsole *)virtio_common_init("virtio-console",
> > >                                              VIRTIO_ID_CONSOLE,
> > > -                                            0, sizeof(VirtIOConsole));
> > > +                                            sizeof(struct virtio_console_config),
> > > +                                            sizeof(VirtIOConsole));
> > 
> > Here, you mean:
> > 
> > VirtIODevice *d = virtio_common_init(....);
> > VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
> > 
> > :)
> 
> Again original code, not my contributions :-)
> 
> > Creation of VirtIODevice *d is not necesary, I found it easier to
> > understand  but it is up to you.
> 
> For virtio-serial, I statically allocated VirtIOSerial and had a vdev
> pointer inside it which virtio_common_init gave me. I can do the same
> here.
> 
> > >      if (s == NULL)
> > >          return NULL;
> > >  
> > 
> > Once you are there, virtio_common_init() can't return NULL, fix it please.
> 
> Original code. But I will take it.
> 
> > > -#define MAX_VIRTIO_CONSOLES 1
> > > +#define MAX_VIRTIO_CONSOLE_PORTS 64
> > 
> > Require that this number is a multiple of 32, and you can simplify all
> > the (foo + 31/32) staff.
> 
> Sure, but it's better to be careful in a couple of places just because
> we can be. Does (foo+31)/32 make it very difficult to read?
> 
> 		Amit
> -- 
> http://log.amitshah.net/
> 
> 

		Amit

Re: [Qemu-devel] Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

On (Thu) Sep 03 2009 [19:56:05], Amit Shah wrote:
> Hi Juan,
> 
> On (Thu) Sep 03 2009 [16:06:54], Juan Quintela wrote:
> > > diff --git a/hw/virtio-console.c b/hw/virtio-console.c
> > > index 663c8b9..da590d2 100644
> > > --- a/hw/virtio-console.c
> > > +++ b/hw/virtio-console.c
> > >  
> > >  #include "hw.h"
> > > +#include "monitor.h"
> > > +#include "pci.h"
> > > +#include "sys-queue.h"
> > >  #include "qemu-char.h"
> > >  #include "virtio.h"
> > >  #include "virtio-console.h"
> > >  
> > > -
> > >  typedef struct VirtIOConsole
> > >  {
> > >      VirtIODevice vdev;
> > > -    VirtQueue *ivq, *dvq;
> > > -    CharDriverState *chr;
> > > +    PCIDevice *dev;
> > 
> > Why do you need dev here?  VirtIODevice already have hidded somewhere
> > a PCIDevice (hidded is a good defenition).
> > virtio-blk and virtio-net are able to work with that pci device.
> 
> Let me check that; I need pci device while initialising a new port (and
> it's slightly different when done at init and when done at hot-add
> time).
> 
> > > +/* Readiness of the guest to accept data on a port */
> > > +static int vcon_can_read(void *opaque)
> > > +{
> > > +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
> > 
> > Cast is not needed here.
> 
> This is original code that I've not modified (just moved around).
> 
> But you're right; I could do that in this patch itself.
> 
> > > +static void virtio_console_set_port_active(uint32_t idx)
> > > +{
> > > +    int i = 0;
> > > +
> > > +    while (idx / 32) {
> > > +        i++;
> > > +        idx -= 32;
> > > +    }
> > 
> > It is just me, or you are doing a division + modulus in a very strange way?
> > 
> >    i = idx / 32;
> >    idx = idx % 32;
> > 
> > ???

Er, sorry I left this out.

That won't work for MAX_PORTS > 32.

But I guess I can just do

i = idx / MAX_VIRTIO_CONSOLE_PORTS;
idx = idx % MAX_VIRTIO_CONSOLE_PORTS;

> > >  static void virtio_console_save(QEMUFile *f, void *opaque)
> > >  {
> > >      VirtIOConsole *s = opaque;
> > > +    unsigned int i;
> > >  
> > > +    /* The virtio device */
> > >      virtio_save(&s->vdev, f);
> > > +    /* The PCI device */
> > > +    pci_device_save(s->dev, f);
> > 
> > If you don't use pci here, virtio_save() should save your pci stuff
> > here.  See the ->load_config() stuff.
> > 
> > Yeap, it can confuse anybody.
> 
> Actually no. Since virtio rides on top of pci, I'd expect virtio_save to
> save pci state too :-)
> 
> I'll check this too.
> 
> > For the new table based vmstate, fields need to live in an struct, in
> > this case VirtIOConsole.
> > 
> > Can you move virtcon_config and virtcon_ports to VirtIOConsole.
> 
> In that case VirtIOConsole has to become a static (instead of being
> allocated via the call to virtio_common_init. Doable.
> 
> > > +    /* The config space */
> > > +    qemu_put_be16s(f, &virtcon_config.cols);
> > > +    qemu_put_be16s(f, &virtcon_config.rows);
> > 
> > > +    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
> > > +    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
> > > +    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
> > > +        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> > > +    }
> > 
> > Don't even try to save a couple of bytes, please.
> 
> Sorry, don't understand this.
> 
> > 
> > for (i = 0; i <  (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
> >     qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> > }
> > 
> > Same for load, please.  Makes the translation to table based way easier.
> 
> OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
> correct?
> 
> I do it this way because we could be migrated from a host that supports
> 64 max ports to a host that supports 128 max ports and then back to the
> one that supports 64 max ports. :-)
> 
> > > +    /* Items in struct VirtIOConsole */
> > > +    qemu_put_be32s(f, &virtio_console->guest_features);
> > 
> > here you mean s->guest_features, right?
> 
> Right!
> 
> > > +    /* Items in struct VirtIOConsolePort */
> > > +    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
> > > +        qemu_put_byte(f, virtcon_ports[i].guest_connected);
> > > +    }
> > 
> > If you want to optimize saving of this field, it is possible that it is
> > a better idea to create another bitmap for it.  What do you think?
> 
> Yes, I wanted to do that as well. The same functions that compute the
> modulo/division earlier can give us this thing as well. But it'll only
> be used for loadvm/savevm. I expect the bool to continue to reside in
> this struct for normal operation.
> 
> > I can't see VMState adding support for bools any time soon, but arrays
> > of bool is a possibility.
> 
> Consider the RFE filed :-)
> 
> > > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
> > >      VirtIOConsole *s;
> > >      s = (VirtIOConsole *)virtio_common_init("virtio-console",
> > >                                              VIRTIO_ID_CONSOLE,
> > > -                                            0, sizeof(VirtIOConsole));
> > > +                                            sizeof(struct virtio_console_config),
> > > +                                            sizeof(VirtIOConsole));
> > 
> > Here, you mean:
> > 
> > VirtIODevice *d = virtio_common_init(....);
> > VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
> > 
> > :)
> 
> Again original code, not my contributions :-)
> 
> > Creation of VirtIODevice *d is not necesary, I found it easier to
> > understand  but it is up to you.
> 
> For virtio-serial, I statically allocated VirtIOSerial and had a vdev
> pointer inside it which virtio_common_init gave me. I can do the same
> here.
> 
> > >      if (s == NULL)
> > >          return NULL;
> > >  
> > 
> > Once you are there, virtio_common_init() can't return NULL, fix it please.
> 
> Original code. But I will take it.
> 
> > > -#define MAX_VIRTIO_CONSOLES 1
> > > +#define MAX_VIRTIO_CONSOLE_PORTS 64
> > 
> > Require that this number is a multiple of 32, and you can simplify all
> > the (foo + 31/32) staff.
> 
> Sure, but it's better to be careful in a couple of places just because
> we can be. Does (foo+31)/32 make it very difficult to read?
> 
> 		Amit
> -- 
> http://log.amitshah.net/
> 
> 

		Amit

Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Juan Quintela]

>> > +    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
>> > +        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
>> > +    }
>> 
>> Don't even try to save a couple of bytes, please.
>
> Sorry, don't understand this.
>
>> 
>> for (i = 0; i <  (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
>>     qemu_put_be32s(f, &virtcon_config.ports_map[i]);
>> }
>> 
>> Same for load, please.  Makes the translation to table based way easier.
>
> OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
> correct?

>> > +    /* Items in struct VirtIOConsolePort */
>> > +    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
>> > +        qemu_put_byte(f, virtcon_ports[i].guest_connected);
>> > +    }
>> 
>> If you want to optimize saving of this field, it is possible that it is
>> a better idea to create another bitmap for it.  What do you think?
>
> Yes, I wanted to do that as well. The same functions that compute the
> modulo/division earlier can give us this thing as well. But it'll only
> be used for loadvm/savevm. I expect the bool to continue to reside in
> this struct for normal operation.
>
>> I can't see VMState adding support for bools any time soon, but arrays
>> of bool is a possibility.
>
> Consider the RFE filed :-)
>
>> > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
>> >      VirtIOConsole *s;
>> >      s = (VirtIOConsole *)virtio_common_init("virtio-console",
>> >                                              VIRTIO_ID_CONSOLE,
>> > -                                            0, sizeof(VirtIOConsole));
>> > +                                            sizeof(struct virtio_console_config),
>> > +                                            sizeof(VirtIOConsole));
>> 
>> Here, you mean:
>> 
>> VirtIODevice *d = virtio_common_init(....);
>> VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
>> 
>> :)
>
> Again original code, not my contributions :-)
>
>> Creation of VirtIODevice *d is not necesary, I found it easier to
>> understand  but it is up to you.
>
> For virtio-serial, I statically allocated VirtIOSerial and had a vdev
> pointer inside it which virtio_common_init gave me. I can do the same
> here.
>
>> >      if (s == NULL)
>> >          return NULL;
>> >  
>> 
>> Once you are there, virtio_common_init() can't return NULL, fix it please.
>
> Original code. But I will take it.
>
>> > -#define MAX_VIRTIO_CONSOLES 1
>> > +#define MAX_VIRTIO_CONSOLE_PORTS 64
>> 
>> Require that this number is a multiple of 32, and you can simplify all
>> the (foo + 31/32) staff.
>
> Sure, but it's better to be careful in a couple of places just because
> we can be. Does (foo+31)/32 make it very difficult to read?

It is easier the other way around, and one assert in an init function
seeing that FOO%32 == 0, and you get the same result.

Later, Juan.

Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Juan Quintela]

>> > +    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
>> > +        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
>> > +    }
>> 
>> Don't even try to save a couple of bytes, please.
>
> Sorry, don't understand this.
>
>> 
>> for (i = 0; i <  (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
>>     qemu_put_be32s(f, &virtcon_config.ports_map[i]);
>> }
>> 
>> Same for load, please.  Makes the translation to table based way easier.
>
> OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
> correct?

>> > +    /* Items in struct VirtIOConsolePort */
>> > +    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
>> > +        qemu_put_byte(f, virtcon_ports[i].guest_connected);
>> > +    }
>> 
>> If you want to optimize saving of this field, it is possible that it is
>> a better idea to create another bitmap for it.  What do you think?
>
> Yes, I wanted to do that as well. The same functions that compute the
> modulo/division earlier can give us this thing as well. But it'll only
> be used for loadvm/savevm. I expect the bool to continue to reside in
> this struct for normal operation.
>
>> I can't see VMState adding support for bools any time soon, but arrays
>> of bool is a possibility.
>
> Consider the RFE filed :-)
>
>> > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
>> >      VirtIOConsole *s;
>> >      s = (VirtIOConsole *)virtio_common_init("virtio-console",
>> >                                              VIRTIO_ID_CONSOLE,
>> > -                                            0, sizeof(VirtIOConsole));
>> > +                                            sizeof(struct virtio_console_config),
>> > +                                            sizeof(VirtIOConsole));
>> 
>> Here, you mean:
>> 
>> VirtIODevice *d = virtio_common_init(....);
>> VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
>> 
>> :)
>
> Again original code, not my contributions :-)
>
>> Creation of VirtIODevice *d is not necesary, I found it easier to
>> understand  but it is up to you.
>
> For virtio-serial, I statically allocated VirtIOSerial and had a vdev
> pointer inside it which virtio_common_init gave me. I can do the same
> here.
>
>> >      if (s == NULL)
>> >          return NULL;
>> >  
>> 
>> Once you are there, virtio_common_init() can't return NULL, fix it please.
>
> Original code. But I will take it.
>
>> > -#define MAX_VIRTIO_CONSOLES 1
>> > +#define MAX_VIRTIO_CONSOLE_PORTS 64
>> 
>> Require that this number is a multiple of 32, and you can simplify all
>> the (foo + 31/32) staff.
>
> Sure, but it's better to be careful in a couple of places just because
> we can be. Does (foo+31)/32 make it very difficult to read?

It is easier the other way around, and one assert in an init function
seeing that FOO%32 == 0, and you get the same result.

Later, Juan.

Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Juan Quintela]

Amit Shah <amit.shah@redhat.com> wrote:

Hi

>> > > +static void virtio_console_set_port_active(uint32_t idx)
>> > > +{
>> > > +    int i = 0;
>> > > +
>> > > +    while (idx / 32) {
>> > > +        i++;
>> > > +        idx -= 32;
>> > > +    }
>> > 
>> > It is just me, or you are doing a division + modulus in a very strange way?
>> > 
>> >    i = idx / 32;
>> >    idx = idx % 32;
>> > 
>> > ???
>
> Er, sorry I left this out.
>
> That won't work for MAX_PORTS > 32.

Why not?

idx = 42
i = 42 / 32 = 1
new_idx = 42 % 32 = 10

virtcon_config.ports_map[i] & (1U<< new_idx)

it gives exactly the same same result than before.

What you are hardcoding is a "very" complex way of doing a division with
remainder, or have I lost something?

> But I guess I can just do
>
> i = idx / MAX_VIRTIO_CONSOLE_PORTS;
> idx = idx % MAX_VIRTIO_CONSOLE_PORTS;
>
>> > >  static void virtio_console_save(QEMUFile *f, void *opaque)
>> > >  {
>> > >      VirtIOConsole *s = opaque;
>> > > +    unsigned int i;
>> > >  
>> > > +    /* The virtio device */
>> > >      virtio_save(&s->vdev, f);
>> > > +    /* The PCI device */
>> > > +    pci_device_save(s->dev, f);
>> > 
>> > If you don't use pci here, virtio_save() should save your pci stuff
>> > here.  See the ->load_config() stuff.
>> > 
>> > Yeap, it can confuse anybody.
>> 
>> Actually no. Since virtio rides on top of pci, I'd expect virtio_save to
>> save pci state too :-)
>> 
>> I'll check this too.
>> 
>> > For the new table based vmstate, fields need to live in an struct, in
>> > this case VirtIOConsole.
>> > 
>> > Can you move virtcon_config and virtcon_ports to VirtIOConsole.
>> 
>> In that case VirtIOConsole has to become a static (instead of being
>> allocated via the call to virtio_common_init. Doable.
>> 
>> > > +    /* The config space */
>> > > +    qemu_put_be16s(f, &virtcon_config.cols);
>> > > +    qemu_put_be16s(f, &virtcon_config.rows);
>> > 
>> > > +    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
>> > > +    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
>> > > +    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
>> > > +        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
>> > > +    }
>> > 
>> > Don't even try to save a couple of bytes, please.
>> 
>> Sorry, don't understand this.
>> 
>> > 
>> > for (i = 0; i <  (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
>> >     qemu_put_be32s(f, &virtcon_config.ports_map[i]);
>> > }
>> > 
>> > Same for load, please.  Makes the translation to table based way easier.
>> 
>> OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
>> correct?
>> 
>> I do it this way because we could be migrated from a host that supports
>> 64 max ports to a host that supports 128 max ports and then back to the
>> one that supports 64 max ports. :-)
>> 
>> > > +    /* Items in struct VirtIOConsole */
>> > > +    qemu_put_be32s(f, &virtio_console->guest_features);
>> > 
>> > here you mean s->guest_features, right?
>> 
>> Right!
>> 
>> > > +    /* Items in struct VirtIOConsolePort */
>> > > +    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
>> > > +        qemu_put_byte(f, virtcon_ports[i].guest_connected);
>> > > +    }
>> > 
>> > If you want to optimize saving of this field, it is possible that it is
>> > a better idea to create another bitmap for it.  What do you think?
>> 
>> Yes, I wanted to do that as well. The same functions that compute the
>> modulo/division earlier can give us this thing as well. But it'll only
>> be used for loadvm/savevm. I expect the bool to continue to reside in
>> this struct for normal operation.
>> 
>> > I can't see VMState adding support for bools any time soon, but arrays
>> > of bool is a possibility.
>> 
>> Consider the RFE filed :-)
>> 
>> > > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
>> > >      VirtIOConsole *s;
>> > >      s = (VirtIOConsole *)virtio_common_init("virtio-console",
>> > >                                              VIRTIO_ID_CONSOLE,
>> > > -                                            0, sizeof(VirtIOConsole));
>> > > +                                            sizeof(struct virtio_console_config),
>> > > +                                            sizeof(VirtIOConsole));
>> > 
>> > Here, you mean:
>> > 
>> > VirtIODevice *d = virtio_common_init(....);
>> > VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
>> > 
>> > :)
>> 
>> Again original code, not my contributions :-)
>> 
>> > Creation of VirtIODevice *d is not necesary, I found it easier to
>> > understand  but it is up to you.
>> 
>> For virtio-serial, I statically allocated VirtIOSerial and had a vdev
>> pointer inside it which virtio_common_init gave me. I can do the same
>> here.
>> 
>> > >      if (s == NULL)
>> > >          return NULL;
>> > >  
>> > 
>> > Once you are there, virtio_common_init() can't return NULL, fix it please.
>> 
>> Original code. But I will take it.
>> 
>> > > -#define MAX_VIRTIO_CONSOLES 1
>> > > +#define MAX_VIRTIO_CONSOLE_PORTS 64
>> > 
>> > Require that this number is a multiple of 32, and you can simplify all
>> > the (foo + 31/32) staff.
>> 
>> Sure, but it's better to be careful in a couple of places just because
>> we can be. Does (foo+31)/32 make it very difficult to read?
>> 
>> 		Amit
>> -- 
>> http://log.amitshah.net/
>> 
>> 
>
> 		Amit

Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Juan Quintela]

Amit Shah <amit.shah@redhat.com> wrote:

Hi

>> > > +static void virtio_console_set_port_active(uint32_t idx)
>> > > +{
>> > > +    int i = 0;
>> > > +
>> > > +    while (idx / 32) {
>> > > +        i++;
>> > > +        idx -= 32;
>> > > +    }
>> > 
>> > It is just me, or you are doing a division + modulus in a very strange way?
>> > 
>> >    i = idx / 32;
>> >    idx = idx % 32;
>> > 
>> > ???
>
> Er, sorry I left this out.
>
> That won't work for MAX_PORTS > 32.

Why not?

idx = 42
i = 42 / 32 = 1
new_idx = 42 % 32 = 10

virtcon_config.ports_map[i] & (1U<< new_idx)

it gives exactly the same same result than before.

What you are hardcoding is a "very" complex way of doing a division with
remainder, or have I lost something?

> But I guess I can just do
>
> i = idx / MAX_VIRTIO_CONSOLE_PORTS;
> idx = idx % MAX_VIRTIO_CONSOLE_PORTS;
>
>> > >  static void virtio_console_save(QEMUFile *f, void *opaque)
>> > >  {
>> > >      VirtIOConsole *s = opaque;
>> > > +    unsigned int i;
>> > >  
>> > > +    /* The virtio device */
>> > >      virtio_save(&s->vdev, f);
>> > > +    /* The PCI device */
>> > > +    pci_device_save(s->dev, f);
>> > 
>> > If you don't use pci here, virtio_save() should save your pci stuff
>> > here.  See the ->load_config() stuff.
>> > 
>> > Yeap, it can confuse anybody.
>> 
>> Actually no. Since virtio rides on top of pci, I'd expect virtio_save to
>> save pci state too :-)
>> 
>> I'll check this too.
>> 
>> > For the new table based vmstate, fields need to live in an struct, in
>> > this case VirtIOConsole.
>> > 
>> > Can you move virtcon_config and virtcon_ports to VirtIOConsole.
>> 
>> In that case VirtIOConsole has to become a static (instead of being
>> allocated via the call to virtio_common_init. Doable.
>> 
>> > > +    /* The config space */
>> > > +    qemu_put_be16s(f, &virtcon_config.cols);
>> > > +    qemu_put_be16s(f, &virtcon_config.rows);
>> > 
>> > > +    qemu_put_be32s(f, &virtcon_config.max_nr_ports);
>> > > +    qemu_put_be32s(f, &virtcon_config.nr_active_ports);
>> > > +    for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
>> > > +        qemu_put_be32s(f, &virtcon_config.ports_map[i]);
>> > > +    }
>> > 
>> > Don't even try to save a couple of bytes, please.
>> 
>> Sorry, don't understand this.
>> 
>> > 
>> > for (i = 0; i <  (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
>> >     qemu_put_be32s(f, &virtcon_config.ports_map[i]);
>> > }
>> > 
>> > Same for load, please.  Makes the translation to table based way easier.
>> 
>> OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
>> correct?
>> 
>> I do it this way because we could be migrated from a host that supports
>> 64 max ports to a host that supports 128 max ports and then back to the
>> one that supports 64 max ports. :-)
>> 
>> > > +    /* Items in struct VirtIOConsole */
>> > > +    qemu_put_be32s(f, &virtio_console->guest_features);
>> > 
>> > here you mean s->guest_features, right?
>> 
>> Right!
>> 
>> > > +    /* Items in struct VirtIOConsolePort */
>> > > +    for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
>> > > +        qemu_put_byte(f, virtcon_ports[i].guest_connected);
>> > > +    }
>> > 
>> > If you want to optimize saving of this field, it is possible that it is
>> > a better idea to create another bitmap for it.  What do you think?
>> 
>> Yes, I wanted to do that as well. The same functions that compute the
>> modulo/division earlier can give us this thing as well. But it'll only
>> be used for loadvm/savevm. I expect the bool to continue to reside in
>> this struct for normal operation.
>> 
>> > I can't see VMState adding support for bools any time soon, but arrays
>> > of bool is a possibility.
>> 
>> Consider the RFE filed :-)
>> 
>> > > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
>> > >      VirtIOConsole *s;
>> > >      s = (VirtIOConsole *)virtio_common_init("virtio-console",
>> > >                                              VIRTIO_ID_CONSOLE,
>> > > -                                            0, sizeof(VirtIOConsole));
>> > > +                                            sizeof(struct virtio_console_config),
>> > > +                                            sizeof(VirtIOConsole));
>> > 
>> > Here, you mean:
>> > 
>> > VirtIODevice *d = virtio_common_init(....);
>> > VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
>> > 
>> > :)
>> 
>> Again original code, not my contributions :-)
>> 
>> > Creation of VirtIODevice *d is not necesary, I found it easier to
>> > understand  but it is up to you.
>> 
>> For virtio-serial, I statically allocated VirtIOSerial and had a vdev
>> pointer inside it which virtio_common_init gave me. I can do the same
>> here.
>> 
>> > >      if (s == NULL)
>> > >          return NULL;
>> > >  
>> > 
>> > Once you are there, virtio_common_init() can't return NULL, fix it please.
>> 
>> Original code. But I will take it.
>> 
>> > > -#define MAX_VIRTIO_CONSOLES 1
>> > > +#define MAX_VIRTIO_CONSOLE_PORTS 64
>> > 
>> > Require that this number is a multiple of 32, and you can simplify all
>> > the (foo + 31/32) staff.
>> 
>> Sure, but it's better to be careful in a couple of places just because
>> we can be. Does (foo+31)/32 make it very difficult to read?
>> 
>> 		Amit
>> -- 
>> http://log.amitshah.net/
>> 
>> 
>
> 		Amit

Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

On (Thu) Sep 03 2009 [17:20:44], Juan Quintela wrote:
> Amit Shah <amit.shah@redhat.com> wrote:
> 
> Hi
> 
> >> > > +static void virtio_console_set_port_active(uint32_t idx)
> >> > > +{
> >> > > +    int i = 0;
> >> > > +
> >> > > +    while (idx / 32) {
> >> > > +        i++;
> >> > > +        idx -= 32;
> >> > > +    }
> >> > 
> >> > It is just me, or you are doing a division + modulus in a very strange way?
> >> > 
> >> >    i = idx / 32;
> >> >    idx = idx % 32;
> >> > 
> >> > ???
> >
> > Er, sorry I left this out.
> >
> > That won't work for MAX_PORTS > 32.
> 
> Why not?

After a good night's sleep, I see that I was wrong :-)

You're right and I don't remember why I did it this way instead of just
using % from the start. Maybe I had a different way of storing it back
then; it's been a long time.

I also saw that I was wrong about the casts:

> > > +/* Readiness of the guest to accept data on a port */
> > > +static int vcon_can_read(void *opaque)
> > > +{
> > > +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
> > 
> > Cast is not needed here.

> This is original code that I've not modified (just moved around).

> But you're right; I could do that in this patch itself.

These were indeed introduced by me (and are now corrected).

Thanks!

		Amit

[Qemu-devel] Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

On (Thu) Sep 03 2009 [17:20:44], Juan Quintela wrote:
> Amit Shah <amit.shah@redhat.com> wrote:
> 
> Hi
> 
> >> > > +static void virtio_console_set_port_active(uint32_t idx)
> >> > > +{
> >> > > +    int i = 0;
> >> > > +
> >> > > +    while (idx / 32) {
> >> > > +        i++;
> >> > > +        idx -= 32;
> >> > > +    }
> >> > 
> >> > It is just me, or you are doing a division + modulus in a very strange way?
> >> > 
> >> >    i = idx / 32;
> >> >    idx = idx % 32;
> >> > 
> >> > ???
> >
> > Er, sorry I left this out.
> >
> > That won't work for MAX_PORTS > 32.
> 
> Why not?

After a good night's sleep, I see that I was wrong :-)

You're right and I don't remember why I did it this way instead of just
using % from the start. Maybe I had a different way of storing it back
then; it's been a long time.

I also saw that I was wrong about the casts:

> > > +/* Readiness of the guest to accept data on a port */
> > > +static int vcon_can_read(void *opaque)
> > > +{
> > > +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
> > 
> > Cast is not needed here.

> This is original code that I've not modified (just moved around).

> But you're right; I could do that in this patch itself.

These were indeed introduced by me (and are now corrected).

Thanks!

		Amit

Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

On (Thu) Sep 03 2009 [17:20:44], Juan Quintela wrote:
> Amit Shah <amit.shah@redhat.com> wrote:
> 
> Hi
> 
> >> > > +static void virtio_console_set_port_active(uint32_t idx)
> >> > > +{
> >> > > +    int i = 0;
> >> > > +
> >> > > +    while (idx / 32) {
> >> > > +        i++;
> >> > > +        idx -= 32;
> >> > > +    }
> >> > 
> >> > It is just me, or you are doing a division + modulus in a very strange way?
> >> > 
> >> >    i = idx / 32;
> >> >    idx = idx % 32;
> >> > 
> >> > ???
> >
> > Er, sorry I left this out.
> >
> > That won't work for MAX_PORTS > 32.
> 
> Why not?

After a good night's sleep, I see that I was wrong :-)

You're right and I don't remember why I did it this way instead of just
using % from the start. Maybe I had a different way of storing it back
then; it's been a long time.

I also saw that I was wrong about the casts:

> > > +/* Readiness of the guest to accept data on a port */
> > > +static int vcon_can_read(void *opaque)
> > > +{
> > > +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
> > 
> > Cast is not needed here.

> This is original code that I've not modified (just moved around).

> But you're right; I could do that in this patch itself.

These were indeed introduced by me (and are now corrected).

Thanks!

		Amit