lkml.org 
[lkml]   [2009]   [Sep]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [PATCH] virtio_console: Add support for multiple ports for generic guest and host communication
    On (Tue) Sep 29 2009 [15:31:23], Christian Borntraeger wrote:
    > Am Dienstag 29 September 2009 15:09:50 schrieb Amit Shah:
    > > Great, thanks. However I was thinking of moving this init to the probe()
    > > routine instead of in the init_conosle routine just because multiple
    > > consoles can be added and we don't want to init this each time.. just
    > > once in probe is fine.
    >
    > If you have new patch CC me and I can give it a spin.

    Hey Christian,

    I have a new patch that changes a few things:
    - moves the put_char fix to probe instead of doing it in
    init_port_console(), which gets called on each console port found.
    - uses port->id instead of a static hvc_vtermno to pass on a value to
    hvc_alloc(). Motivation explained within comments in the code.
    - A few other changes that introduce and make use of port->vcon instead
    of accessing the static virtconsole directly -- aimed at easing future
    fix to have multiple virtio-console devices.

    It would be great if you could test this.

    Amit


    diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
    index 6a06913..7b4602f 100644
    --- a/drivers/char/Kconfig
    +++ b/drivers/char/Kconfig
    @@ -679,6 +679,12 @@ config VIRTIO_CONSOLE
    help
    Virtio console for use with lguest and other hypervisors.

    + Also serves as a general-purpose serial device for data
    + transfer between the guest and host. Character devices at
    + /dev/vconNN will be created when corresponding ports are
    + found. If specified by the host, a sysfs attribute called
    + 'name' will be populated with a name for the port which can
    + be used by udev scripts to create a symlink to /dev/vconNN.

    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..16cdcec 100644
    --- a/drivers/char/virtio_console.c
    +++ b/drivers/char/virtio_console.c
    @@ -9,10 +9,8 @@
    * functions.
    :*/

    -/*M:002 The console can be flooded: while the Guest is processing input the
    - * Host can send more. Buffering in the Host could alleviate this, but it is a
    - * difficult problem in general. :*/
    /* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
    + * Copyright (C) 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
    @@ -28,115 +26,468 @@
    * 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
    - * operations for them. */
    -static struct virtqueue *in_vq, *out_vq;
    -static struct virtio_device *vdev;
    +/* This struct stores data that's common to all the ports */
    +struct virtio_console_struct {
    + /*
    + * Workqueue handlers where we process deferred work after an
    + * interrupt
    + */
    + 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;
    + /* The input and the output queues */
    + 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)
    + /* The current config space is stored here */
    + 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;
    +
    + /* length of the buffer */
    + size_t len;
    + /* offset in the buf from which to consume data */
    + size_t offset;
    +};
    +
    +/* This struct holds the per-port data */
    +struct virtio_console_port {
    + /* Next port in the list, head is in the virtio_console_struct */
    + struct list_head next;
    +
    + /* Pointer to the virtio_console device */
    + struct virtio_console_struct *vcon;
    +
    + /* Buffer management */
    + struct list_head readbuf_head;
    +
    + /* A waitqueue for poll() or blocking read operations */
    + 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;
    +
    + /* The 'name' of the port that we expose via sysfs properties */
    + char *name;
    +
    + /* The 'id' to identify the port with the Host */
    + u32 id;
    +
    + /* Is the host device open */
    + bool host_connected;
    +};
    +
    +static struct virtio_console_struct virtconsole;
    +
    +static struct virtio_console_port *get_port_from_devt(dev_t devt)
    {
    - 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 (port->dev->devt == devt)
    + return port;
    }
    + return NULL;
    +}
    +
    +static struct virtio_console_port *get_port_from_id(u32 id)
    +{
    + struct virtio_console_port *port;

    - /* We're expected to return the amount of data we wrote: all of it. */
    - return count;
    + list_for_each_entry(port, &virtconsole.port_head, next) {
    + if (port->id == id)
    + return port;
    + }
    + return NULL;
    }

    -/* Create a scatter-gather list representing our input buffer and put it in the
    - * queue. */
    -static void add_inbuf(void)
    +static int get_id_from_port(struct virtio_console_port *port)
    {
    - struct scatterlist sg[1];
    - sg_init_one(sg, inbuf, PAGE_SIZE);
    + return port->id;
    +}

    - /* 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);
    +static bool is_console_port(struct virtio_console_port *port)
    +{
    + if (port->hvc)
    + 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;
    +}
    +
    +/*
    + * Give out the data that's requested from the buffers that we have
    + * queued up per port
    + */
    +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;
    +}
    +
    +/* The condition that must be true for polling to end */
    +static bool wait_is_over(struct virtio_console_port *port)
    +{
    + return !list_empty(&port->readbuf_head) || !port->host_connected;
    +}
    +
    +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;

    - /* No buffer? Try to get one. */
    - if (!in_len) {
    - in = in_vq->vq_ops->get_buf(in_vq, &in_len);
    - if (!in)
    + 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;

    - /* You want more than we have to give? Well, try wanting less! */
    - if (in_len < count)
    - count = in_len;
    + 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 should not send internal messages to a host that won't
    + * understand them
    + */
    + 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);
    + }
    + in_offset = 0; /* offset in the user buffer */
    + while (in_count - in_offset) {
    + copy_size = min(in_count - in_offset + header_len, PAGE_SIZE);

    - /* Copy across to their buffer and increment offset. */
    - memcpy(buf, in, count);
    - in += count;
    - in_len -= count;
    + 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 behaviour */
    + }
    + buf->len = header_len + copy_size - ret;
    + sg_init_one(sg, buf->buf, buf->len);

    - /* Finished? Re-register buffer so Host will use it again. */
    - if (in_len == 0)
    - add_inbuf();
    + ret = out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, buf);
    + if (ret < 0) {
    + 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);
    + 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;

    - return count;
    + /* No space left in the vq anyway */
    + if (!ret)
    + break;
    + }
    + /* 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;
    }
    -/*:*/

    -/*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 ssize_t virtconsole_write(struct file *filp, const char __user *ubuf,
    + size_t count, loff_t *offp)
    +{
    + struct virtio_console_port *port;
    +
    + port = filp->private_data;
    +
    + return send_buf(port, ubuf, count, 0, true);
    +}
    +
    +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;
    +}
    +
    +/*
    + * The file operations that we support: programs in the guest can open
    + * a console device, read from it, write to it, poll for data and
    + * close it. The devices are at /dev/vconNN
    + */
    +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,
    +};
    +
    +
    +static ssize_t show_port_name(struct device *dev,
    + struct device_attribute *attr, char *buffer)
    +{
    + struct virtio_console_port *port;
    +
    + port = get_port_from_devt(dev->devt);
    + if (!port || !port->name)
    + return 0;
    +
    + return sprintf(buffer, "%s\n", port->name);
    +}
    +
    +static DEVICE_ATTR(name, S_IRUGO, show_port_name, NULL);
    +
    +static struct attribute *virtcon_sysfs_entries[] = {
    + &dev_attr_name.attr,
    + NULL
    +};
    +
    +static struct attribute_group virtcon_attribute_group = {
    + .name = NULL, /* put in device directory */
    + .attrs = virtcon_sysfs_entries,
    +};
    +
    +
    +/*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.
    + *
    + * If the data to be outpu spans more than a page, it's split into
    + * page-sized buffers and then individual buffers are pushed to Host.
    + */
    +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.
    + *
    + * We call out to fill_readbuf that gets us the required data from the
    + * buffers that are queued up.
    + */
    +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:
    @@ -153,98 +504,579 @@ 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 (VIRTIO_CONSOLE_F_MULTPORT+),
    + * use internal messages to indicate console size
    + * changes so that it can be done per-port
    + */
    + if (!use_multiport())
    + hvc_resize(get_port_from_id(0)->hvc, ws);
    }
    }

    /*
    - * we support only one console, the hvc struct is a global var
    * We set the configuration at this point, since we now have a tty
    */
    -static 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))
    {
    - if (hvc_poll(hvc))
    - hvc_kick();
    + virtio_cons.put_chars = put_chars;
    + return hvc_instantiate(0, 0, &virtio_cons);
    }

    -/*D:370 Once we're further in boot, we get probed like any other virtio device.
    - * At this stage we set up the output virtqueue.
    +int init_port_console(struct virtio_console_port *port)
    +{
    + int ret = 0;
    +
    + /*
    + * The Host's telling us this port is a console port. Hook it
    + * up with an hvc console.
    + *
    + * To set up and manage our virtual console, we call
    + * hvc_alloc().
    + *
    + * The first argument of hvc_alloc() is the virtual console
    + * number. hvc_alloc() checks if a console with the same value
    + * was used in hvc_instantiate(). We may not end up passing
    + * the same value here (we use the value 0 in
    + * hvc_instantiate() but the console port may not be at id
    + * 0). This isn't a problem, though. Nothing in hvc really
    + * depends on these numbers and since this number is passed on
    + * to us when cons_get/put_chars() is called, it's preferable
    + * to pass on the port->id so that we can get the port struct
    + * via get_port_from_id().
    + *
    + * 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->id, 0, &virtio_cons, PAGE_SIZE);
    + if (IS_ERR(port->hvc)) {
    + ret = PTR_ERR(port->hvc);
    + pr_err("%s: Could not alloc hvc for virtio console port, ret = %d\n",
    + __func__, ret);
    + port->hvc = NULL;
    + }
    + return ret;
    +}
    +
    +/* Any secret messages that the Host and Guest want to share */
    +static void handle_control_message(struct virtio_console_port *port,
    + struct virtio_console_port_buffer *buf)
    +{
    + struct virtio_console_control *cpkt;
    + size_t name_size;
    +
    + cpkt = (struct virtio_console_control *)(buf->buf + buf->offset);
    +
    + switch (cpkt->event) {
    + case VIRTIO_CONSOLE_PORT_OPEN:
    + port->host_connected = cpkt->value;
    + break;
    + case VIRTIO_CONSOLE_PORT_NAME:
    + /*
    + * Skip the size of the header and the cpkt to get the size
    + * of the name that was sent
    + */
    + name_size = buf->len - buf->offset - sizeof(*cpkt) + 1;
    +
    + port->name = kmalloc(name_size, GFP_KERNEL);
    + if (!port->name) {
    + pr_err("%s: not enough space to store port name\n",
    + __func__);
    + break;
    + }
    + strncpy(port->name, buf->buf + buf->offset + sizeof(*cpkt),
    + name_size - 1);
    + port->name[name_size - 1] = 0;
    + break;
    + case VIRTIO_CONSOLE_CONSOLE_PORT:
    + if (!cpkt->value)
    + break;
    + init_port_console(port);
    + /*
    + * Could remove the port here in case init fails - but
    + * have to notify the host first
    + */
    + break;
    + }
    +}
    +
    +
    +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)
    +{
    + 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(struct virtio_console_struct *vcon)
    +{
    + fill_queue(vcon->in_vq, PAGE_SIZE, &vcon->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(struct virtio_console_struct *vcon)
    +{
    + 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, &vcon->unused_write_head);
    + }
    +}
    +
    +/*
    + * The workhandler for any buffers that appear on our input queue.
    + * Pick the buffer; if it's some internal communication meant for the
    + * us, just process it. Otherwise queue it up for the read() or
    + * get_chars() routines to pick the data up later.
    + */
    +static void virtio_console_rx_work_handler(struct work_struct *work)
    +{
    + struct virtio_console_struct *vcon;
    + struct virtio_console_port *port;
    + struct virtio_console_port_buffer *buf;
    + struct virtio_console_header header;
    + struct virtqueue *vq;
    + unsigned int tmplen, header_len;
    +
    + vcon = container_of(work, struct virtio_console_struct, rx_work);
    + header_len = use_multiport() ? sizeof(header) : 0;
    +
    + port = NULL;
    + vq = vcon->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(0);
    + if (!port) {
    + /* No valid header at start of buffer. Drop it. */
    + pr_debug("%s: invalid index in buffer, %c %d\n",
    + __func__, buf->buf[0], buf->buf[0]);
    + /*
    + * OPT: This buffer can be added to the unused
    + * list to avoid free / alloc
    + */
    + kfree(buf->buf);
    + kfree(buf);
    + break;
    + }
    + buf->len = tmplen;
    + buf->offset = header_len;
    + if (use_multiport() && is_internal(header.flags)) {
    + handle_control_message(port, buf);
    + /*
    + * OPT: This buffer can be added to the unused
    + * list to avoid free/alloc
    + */
    + kfree(buf->buf);
    + kfree(buf);
    + } else {
    + 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);
    + }
    + if (port) {
    + if(is_console_port(port) && !list_empty(&port->readbuf_head))
    + if (hvc_poll(port->hvc))
    + hvc_kick();
    + /* Allocate buffers for all the ones that got used up */
    + fill_receive_queue(port->vcon);
    + }
    +}
    +
    +/*
    + * This is the workhandler for buffers that get received on the output
    + * virtqueue, which is an indication that Host consumed the data we
    + * sent it. Since all our buffers going out are of a fixed size we can
    + * just reuse them instead of freeing them and allocating new ones.
    *
    - * To set up and manage our virtual console, we call hvc_alloc(). Since we
    - * never remove the console device we never need this pointer again.
    + * Zero out the buffer so that we don't leak any information from
    + * other processes. There's a small optimisation here as well: the
    + * buffers are PAGE_SIZE-sized; but instead of zeroing the entire
    + * page, we just zero the length that was most recently used and we
    + * can be sure the rest of the page is already set to 0s.
    *
    - * Finally we put our input buffer in the input queue, ready to receive. */
    -static int __devinit virtcons_probe(struct virtio_device *dev)
    + * So once we zero them out we add them back to the unused buffers
    + * list
    + */
    +static void virtio_console_tx_work_handler(struct work_struct *work)
    {
    - vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
    + struct virtio_console_struct *vcon;
    + struct virtqueue *vq;
    + struct virtio_console_port_buffer *buf;
    + unsigned int tmplen;
    +
    + vcon = container_of(work, struct virtio_console_struct, tx_work);
    +
    + vq = vcon->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(&vcon->write_list_lock);
    + list_add_tail(&buf->next, &vcon->unused_write_head);
    + spin_unlock(&vcon->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 int virtconsole_add_port(u32 port_nr)
    +{
    + struct virtio_console_port *port;
    + struct virtio_console_control cpkt;
    + dev_t devt;
    + int ret;
    +
    + port = kzalloc(sizeof(*port), GFP_KERNEL);
    + if (!port)
    + return -ENOMEM;
    +
    + port->vcon = &virtconsole;
    + port->id = port_nr;
    +
    + cdev_init(&port->cdev, &virtconsole_fops);
    +
    + ret = alloc_chrdev_region(&devt, 0, 1, "virtio-console");
    + if (ret < 0) {
    + pr_err("%s: error allocing chrdev region, ret = %d\n",
    + __func__, ret);
    + goto free_port;
    + }
    + ret = cdev_add(&port->cdev, devt, 1);
    + if (ret < 0) {
    + pr_err("%s: error adding cdev, ret = %d\n", __func__, ret);
    + goto free_chrdev;
    + }
    + port->dev = device_create(port->vcon->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;
    + }
    + ret = sysfs_create_group(&port->dev->kobj, &virtcon_attribute_group);
    + if (ret) {
    + pr_err("%s: error creating sysfs device attributes, ret = %d\n",
    + __func__, ret);
    + goto free_cdev;
    + }
    +
    + INIT_LIST_HEAD(&port->readbuf_head);
    + init_waitqueue_head(&port->waitqueue);
    +
    + list_add_tail(&port->next, &port->vcon->port_head);
    +
    + /*
    + * Ask for the port's name from Host. The string that we
    + * receive in 'name' can be of arbitrary length; so pass the
    + * maximum available buffer size: PAGE_SIZE.
    + */
    + cpkt.event = VIRTIO_CONSOLE_PORT_NAME;
    + send_buf(port, (char *)&cpkt, sizeof(cpkt),
    + VIRTIO_CONSOLE_ID_INTERNAL, false);
    +
    + /*
    + * If we're not using multiport support, this has to be a console port
    + */
    + if (!use_multiport()) {
    + ret = init_port_console(port);
    + if (ret)
    + goto free_cdev;
    + }
    +
    + pr_debug("virtio-console port found at id %u\n", port_nr);
    +
    + return 0;
    +free_cdev:
    + cdev_del(&port->cdev);
    +free_chrdev:
    + unregister_chrdev_region(devt, 1);
    +free_port:
    + kfree(port);
    + return ret;
    +}
    +
    +
    +/* The workhandler for config-space updates
    + *
    + * This is used when new ports are added
    + */
    +static void virtio_console_config_work_handler(struct work_struct *work)
    +{
    + struct virtio_console_struct *vcon;
    + struct virtio_console_config virtconconf;
    + struct virtio_device *vdev;
    + u32 i;
    + int ret;
    +
    + vcon = container_of(work, struct virtio_console_struct, config_work);
    +
    + vdev = vcon->vdev;
    + vdev->config->get(vdev,
    + offsetof(struct virtio_console_config, nr_active_ports),
    + &virtconconf.nr_active_ports,
    + sizeof(virtconconf.nr_active_ports));
    +
    + /* Hot-add ports */
    + for (i = virtconsole.config.nr_active_ports;
    + i < virtconconf.nr_active_ports; i++) {
    + ret = virtconsole_add_port(virtconsole.config.nr_active_ports + i);
    + if (!ret)
    + virtconsole.config.nr_active_ports++;
    + }
    +}
    +
    +/*D:370
    + * Once we're further in boot, we get probed like any other virtio device.
    + * At this stage we set up the output virtqueue.
    + *
    + * Finally we put our input buffer in the input queue, ready to receive.
    + */
    +static int __devinit virtcons_probe(struct virtio_device *vdev)
    +{
    + vq_callback_t *callbacks[] = { rx_intr, tx_intr };
    const char *names[] = { "input", "output" };
    struct virtqueue *vqs[2];
    - int err;
    + u32 i;
    + int ret;
    + bool multiport;

    - 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;
    + if (virtconsole.vdev) {
    + pr_err("Multiple virtio-console devices not supported yet\n");
    + return -EEXIST;
    }
    + 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,
    + nr_active_ports),
    + &virtconsole.config.nr_active_ports,
    + sizeof(virtconsole.config.nr_active_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;
    + /*
    + * We had set the virtio_cons put_chars implementation to
    + * put_chars for early_init. Now that we're done with the
    + * early init phase, replace it with our cons_put_chars
    + * implementation.
    + */
    + virtio_cons.put_chars = cons_put_chars;
    +
    + INIT_LIST_HEAD(&virtconsole.port_head);
    + INIT_LIST_HEAD(&virtconsole.unused_read_head);
    + INIT_LIST_HEAD(&virtconsole.unused_write_head);
    +
    + 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(&virtconsole);
    + alloc_write_bufs(&virtconsole);
    +
    + virtconsole_add_port(0);
    + if (multiport)
    + for (i = 1; i < virtconsole.config.nr_active_ports; i++)
    + virtconsole_add_port(i);
    +
    + return 0;
    +
    +fail:
    + return ret;
    +}
    +
    +/*
    + * Remove port-specific data.
    + * In case the port can't be removed, return non-zero. This could
    + * then be used in the port hot-unplug case.
    + */
    +static int virtcons_remove_port_data(struct virtio_console_port *port)
    +{
    + struct virtio_console_port_buffer *buf, *buf2;
    +
    + if (is_console_port(port)) {
    + /* hvc_console is compiled in, at least on Fedora. */
    + /* hvc_remove(hvc); */
    + return 1;
    }

    - /* Register the input buffer the first time. */
    - add_inbuf();
    + sysfs_remove_group(&port->dev->kobj, &virtcon_attribute_group);
    + device_destroy(virtconsole.class, port->dev->devt);
    + unregister_chrdev_region(port->dev->devt, 1);
    + cdev_del(&port->cdev);
    +
    + kfree(port->name);
    +
    + /* 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);
    + }
    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;
    +
    + class_destroy(virtconsole.class);
    +
    + cancel_work_sync(&virtconsole.rx_work);
    + /*
    + * Free up the buffers that we queued up for the Host to pass
    + * us data
    + */
    + 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 sent to us by Host but were
    + * left 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);
    + }
    }

    static struct virtio_device_id id_table[] = {
    @@ -254,6 +1086,7 @@ 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 +1096,34 @@ 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..96bb6f0 100644
    --- a/include/linux/virtio_console.h
    +++ b/include/linux/virtio_console.h
    @@ -2,19 +2,63 @@
    #define _LINUX_VIRTIO_CONSOLE_H
    #include <linux/types.h>
    #include <linux/virtio_config.h>
    -/* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
    - * anyone can use the definitions to implement compatible drivers/servers. */
    +/*
    + * This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
    + * anyone can use the definitions to implement compatible drivers/servers.
    + *
    + * Copyright (C) Red Hat, Inc., 2009
    + */

    /* 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 */

    struct virtio_console_config {
    /* colums of the screens */
    __u16 cols;
    /* rows of the screens */
    __u16 rows;
    + /* number of ports in use */
    + __u32 nr_active_ports;
    +} __attribute__((packed));
    +
    +
    +/*
    + * An internal-only message that's passed between the Host and the
    + * Guest for a particular port.
    + */
    +struct virtio_console_control {
    + __u16 event;
    + __u16 value;
    +};
    +
    +/* Some events for internal messages (control packets) */
    +#define VIRTIO_CONSOLE_PORT_OPEN 0
    +#define VIRTIO_CONSOLE_PORT_NAME 1
    +#define VIRTIO_CONSOLE_CONSOLE_PORT 2
    +
    +
    +/*
    + * This struct is put in each buffer that gets passed to userspace and
    + * vice-versa
    + */
    +struct virtio_console_header {
    + /* Port number */
    + u32 id;
    + /* Some message between host and guest */
    + u32 flags;
    + /*
    + * Complete size of the write request - only sent with the
    + * first buffer for each write request
    + */
    + u32 size;
    } __attribute__((packed));

    +/* Messages between host and guest ('flags' field in the header above) */
    +#define VIRTIO_CONSOLE_ID_INTERNAL (1 << 0)
    +

    #ifdef __KERNEL__
    int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int));

    \
     
     \ /
      Last update: 2009-09-30 19:17    [W:0.096 / U:0.480 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site