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

Amit Shah
2009-08-25T06:18:19Z

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 | 871 +++++++++++++++++++++++++++++++++++-----
include/linux/virtio_console.h | 27 ++
3 files changed, 791 insertions(+), 111 deletions(-)

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 6a06913..fe76627 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 c74dacf..3548bf6 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
@@ -28,100 +29,374 @@
* 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/virtio.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;
+
+ struct list_head port_head;
+ struct list_head unused_read_head;
+
+ struct virtio_device *vdev;
+ struct class *class;
+ struct virtqueue *in_vq, *out_vq;
+
+ struct virtio_console_config *config;
+};
+
+/* This struct holds individual buffers received for each port */
+struct virtio_console_port_buffer {
+ struct list_head next;

-/* This is our input buffer, and how much data is left in it. */
-static unsigned int in_len;
-static char *in, *inbuf;
+ 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 virtio_console_port_buffer read_buf;
+ struct list_head readbuf_head;
+ wait_queue_head_t waitqueue;
+
+ /* Each port associates with a separate char device */
+ struct cdev cdev;
+ struct device *dev;
+
+ bool host_connected; /* Is the host device open */
+};
+
+static struct virtio_console_struct virtconsole;
+
+static int major = 60; /* from the experimental range */

/* The operations for our console. */
+/* FIXME: this should go into the per-port struct */
static struct hv_ops virtio_cons;

/* The hvc device */
static struct hvc_struct *hvc;

-/*D:310 The put_chars() callback is pretty straightforward.
+static struct virtio_console_port *get_port_from_id(u32 id)
+{
+ struct virtio_console_port *port;
+
+ list_for_each_entry(port, &virtconsole.port_head, next) {
+ if (MINOR(port->dev->devt) == id)
+ return port;
+ }
+ return NULL;
+}
+
+static int get_id_from_port(struct virtio_console_port *port)
+{
+ return MINOR(port->dev->devt);
+}
+
+static inline bool use_multiport(void)
+{
+ return virtconsole.vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+}
+
+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 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;
+
+ ret = 0;
+ if (list_empty(&port->readbuf_head)) {
+ if (filp->f_flags & O_NONBLOCK)
+ return -EAGAIN;
+
+ ret = wait_event_interruptible(port->waitqueue,
+ !list_empty(&port->readbuf_head));
+ }
+ if (ret < 0)
+ return ret;
+
+ return fill_readbuf(port, ubuf, count, true);
+}
+
+/* For data that exceeds PAGE_SIZE in size we should send it all in
+ * one sg to not unnecessarily split up the data. Also some (all?)
+ * vnc clients don't consume split data.
*
- * 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)
+ * If we are to keep PAGE_SIZE sized buffers, we then have to stack
+ * multiple of those in one virtio request. virtio-ring returns to us
+ * just one pointer for all the buffers. So use this struct to
+ * allocate the bufs in so that freeing this up later is easier.
+ */
+struct vbuf {
+ char **bufs;
+ struct scatterlist *sg;
+ unsigned int nent;
+};
+
+static ssize_t send_buf(struct virtio_console_port *port,
+ const char *in_buf, size_t in_count,
+ bool from_user, bool internal)
{
- 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 virtqueue *out_vq;
+ struct virtio_console_header header;
+ struct vbuf *vbuf;
+ size_t in_offset, copy_size;
+ ssize_t ret;
+ unsigned int i, 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() && internal) {
+ return 0;
+ }
+ header_len = 0;
+ if (use_multiport()) {
+ header.id = get_id_from_port(port);
+ header.internal_message = internal;
+ header_len = sizeof(header);
+ }
+ ret = -ENOMEM;
+ vbuf = kzalloc(sizeof(struct vbuf), GFP_KERNEL);
+ if (!vbuf)
+ return ret;
+
+ /* Max. number of buffers clubbed together in one message */
+ vbuf->nent = (in_count + header_len + PAGE_SIZE - 1) / PAGE_SIZE;
+
+ vbuf->bufs = kzalloc(sizeof(char *) * vbuf->nent, GFP_KERNEL);
+ if (!vbuf->bufs)
+ goto free_vbuf;
+
+ vbuf->sg = kzalloc(sizeof(struct scatterlist) * vbuf->nent, GFP_KERNEL);
+ if (!vbuf->sg)
+ goto free_bufs;
+ sg_init_table(vbuf->sg, vbuf->nent);
+
+ i = 0; /* vbuf->bufs[i] */
+ in_offset = 0; /* offset in the user buffer */
+ while (in_count - in_offset) {
+ copy_size = min(in_count - in_offset + header_len, PAGE_SIZE);
+ vbuf->bufs[i] = kzalloc(copy_size, GFP_KERNEL);
+ if (!vbuf->bufs[i]) {
+ ret = -ENOMEM;
+ if (!i)
+ goto free_sg;
+ goto free_buffers;
+ }
+ if (header_len) {
+ memcpy(vbuf->bufs[i], &header, header_len);
+ copy_size -= header_len;
+ }
+ if (from_user)
+ ret = copy_from_user(vbuf->bufs[i] + 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(vbuf->bufs[i] + header_len,
+ in_buf + in_offset, copy_size);
+ ret = 0; /* Emulate copy_from_user */
+ }
+ in_offset += copy_size - ret;
+
+ sg_set_buf(&vbuf->sg[i], vbuf->bufs[i],
+ copy_size - ret + header_len);
+ header_len = 0; /* Pass the header only in the first buffer */
+ i++;
+ }
+ if (out_vq->vq_ops->add_buf(out_vq, vbuf->sg, i, 0, vbuf)) {
+ ret = -EIO;
+ goto free_buffers;
}
+ /* Tell Host to go! */
+ out_vq->vq_ops->kick(out_vq);
+
+ /* We're expected to return the amount of data we wrote */
+ return in_offset;
+free_buffers:
+ while (--i >= 0)
+ kfree(vbuf->bufs[i]);
+free_sg:
+ kfree(vbuf->sg);
+free_bufs:
+ kfree(vbuf->bufs);
+free_vbuf:
+ kfree(vbuf);
+ return ret;
+}
+
+static ssize_t virtconsole_write(struct file *filp, const char __user *ubuf,
+ size_t count, loff_t *offp)
+{
+ struct virtio_console_port *port;

- /* We're expected to return the amount of data we wrote: all of it. */
- return count;
+ port = filp->private_data;
+
+ return send_buf(port, ubuf, count, 1, 0);
}

-/* Create a scatter-gather list representing our input buffer and put it in the
- * queue. */
-static void add_inbuf(void)
+static unsigned int virtconsole_poll(struct file *filp, poll_table *wait)
{
- struct scatterlist sg[1];
- sg_init_one(sg, inbuf, PAGE_SIZE);
+ struct virtio_console_port *port;
+ unsigned int ret;
+
+ port = filp->private_data;
+ poll_wait(filp, &port->waitqueue, wait);

- /* 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);
+ ret = 0;
+ if (!list_empty(&port->readbuf_head))
+ ret |= POLLIN | POLLRDNORM;
+
+ return ret;
}

-/*D:350 get_chars() is the callback from the hvc_console infrastructure when
- * an interrupt is received.
+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), false, true);
+
+ 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), false, true);
+
+ 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.
+ *
+ * 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)
+{
+ struct virtio_console_port *port;
+
+ port = get_port_from_id(vtermno);
+ if (!port)
+ return 0;
+
+ return send_buf(port, buf, count, false, 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 get_chars(u32 vtermno, char *buf, int count)
+static int cons_get_chars(u32 vtermno, char *buf, int count)
{
- /* If we don't have an input queue yet, we can't get input. */
- BUG_ON(!in_vq);
+ struct virtio_console_port *port;

- /* No buffer? Try to get one. */
- if (!in_len) {
- in = in_vq->vq_ops->get_buf(in_vq, &in_len);
- if (!in)
- return 0;
- }
+ /* If we don't have an input queue yet, we can't get input. */
+ BUG_ON(!virtconsole.in_vq);

- /* You want more than we have to give? Well, try wanting less! */
- if (in_len < count)
- count = in_len;
+ port = get_port_from_id(vtermno);
+ if (!port)
+ return 0;

- /* Copy across to their buffer and increment offset. */
- memcpy(buf, in, count);
- in += count;
- in_len -= count;
+ if (list_empty(&port->readbuf_head))
+ return 0;

- /* Finished? Re-register buffer so Host will use it again. */
- if (in_len == 0)
- add_inbuf();
+ return fill_readbuf(port, buf, count, false);

- return count;
}
/*:*/

@@ -160,23 +435,317 @@ 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)
+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;
+
+ while (1) {
+ /* We have to keep track of the unused buffers
+ * so that they can be freed when the module
+ * is being removed
+ */
+ buf = kzalloc(sizeof(*buf), GFP_KERNEL);
+ if (!buf)
+ break;
+ buf->buf = kzalloc(buf_size, GFP_KERNEL);
+ if (!buf->buf) {
+ kfree(buf);
+ break;
+ }
+ sg_init_one(sg, buf->buf, buf_size);
+
+ if (vq->vq_ops->add_buf(vq, sg, 0, 1, buf->buf) < 0) {
+ kfree(buf->buf);
+ kfree(buf);
+ break;
+ }
+ list_add_tail(&buf->next, unused_head);
+ }
+ vq->vq_ops->kick(vq);
+}
+
+static void fill_receive_queue(void)
+{
+ fill_queue(virtconsole.in_vq, PAGE_SIZE, &virtconsole.unused_read_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 = NULL;
+ struct virtio_console_port_buffer *buf;
+ struct virtio_console_header header;
+ struct virtqueue *vq;
+ char *tmpbuf;
+ unsigned int tmplen, header_len;
+
+ header_len = use_multiport() ? sizeof(header) : 0;
+
+ vq = virtconsole.in_vq;
+ while ((tmpbuf = vq->vq_ops->get_buf(vq, &tmplen))) {
+ list_for_each_entry(buf, &virtconsole.unused_read_head, next) {
+ if (tmpbuf == buf->buf)
+ break;
+ }
+ BUG_ON(!buf);
+ /* 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() && header.internal_message) {
+ handle_control_message(port,
+ (struct virtio_console_control *)
+ (tmpbuf + header_len));
+
+ /* FIXME: 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);
+ }
+ wake_up_interruptible(&port->waitqueue);
+ }
+
+ if (get_id_from_port(port) == VIRTIO_CONSOLE_CONSOLE_PORT && hvc_poll(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 vbuf *vbuf;
+ unsigned int tmplen;
+ unsigned int i;
+
+ vq = virtconsole.out_vq;
+ while ((vbuf = vq->vq_ops->get_buf(vq, &tmplen))) {
+ for (i = 0; i < vbuf->nent; i++) {
+ kfree(vbuf->bufs[i]);
+ }
+ kfree(vbuf->bufs);
+ kfree(vbuf->sg);
+ kfree(vbuf);
+ }
+}
+
+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 (port_nr == VIRTIO_CONSOLE_CONSOLE_PORT) {
+ /* Start using the new console output. */
+ virtio_cons.get_chars = cons_get_chars;
+ virtio_cons.put_chars = cons_put_chars;
+ virtio_cons.notifier_add = cons_notifier_add_vio;
+ virtio_cons.notifier_del = cons_notifier_del_vio;
+ virtio_cons.notifier_hangup = cons_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)) {
+ ret = PTR_ERR(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.
@@ -186,64 +755,132 @@ 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];

- /* 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;
- }
+ INIT_LIST_HEAD(&virtconsole.port_head);
+ INIT_LIST_HEAD(&virtconsole.unused_read_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);

- /* Register the input buffer the first time. */
- add_inbuf();
+ fill_receive_queue();
return 0;

-free_vqs:
- vdev->config->del_vqs(vdev);
-free:
- kfree(inbuf);
fail:
- return err;
+ return ret;
+}
+
+static void virtconsole_remove_port_data(struct virtio_console_port *port)
+{
+ struct virtio_console_port_buffer *buf, *buf2;
+
+ 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);
+ }
+}
+
+static void virtconsole_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);
+
+ vdev->config->del_vqs(vdev);
+
+ /* 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(port, port2, &virtconsole.port_head, next) {
+ list_del(&port->next);
+ virtconsole_remove_port_data(port);
+ kfree(port);
+ }
+ kfree(virtconsole.config);
}

static struct virtio_device_id id_table[] = {
@@ -253,6 +890,7 @@ static struct virtio_device_id id_table[] = {

static unsigned int features[] = {
VIRTIO_CONSOLE_F_SIZE,
+ VIRTIO_CONSOLE_F_MULTIPORT,
};

static struct virtio_driver virtio_console = {
@@ -262,12 +900,25 @@ static struct virtio_driver virtio_console = {
.driver.owner = THIS_MODULE,
.id_table = id_table,
.probe = virtcons_probe,
- .config_changed = virtcons_apply_config,
+ .config_changed = config_intr,
};

static int __init init(void)
{
- 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;
}
module_init(init);

diff --git a/include/linux/virtio_console.h b/include/linux/virtio_console.h
index dc16111..2197e37 100644
--- a/include/linux/virtio_console.h
+++ b/include/linux/virtio_console.h
@@ -10,14 +10,41 @@

/* 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

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 */
+ bool internal_message; /* Some message between host and guest */
} __attribute__((packed));

+/* 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