diff options
Diffstat (limited to 'drivers/char/virtio_console.c')
| -rw-r--r-- | drivers/char/virtio_console.c | 1858 |
1 files changed, 1858 insertions, 0 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c new file mode 100644 index 00000000000..84b164d1eb2 --- /dev/null +++ b/drivers/char/virtio_console.c @@ -0,0 +1,1858 @@ +/* + * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation + * Copyright (C) 2009, 2010, 2011 Red Hat, Inc. + * Copyright (C) 2009, 2010, 2011 Amit Shah <amit.shah@redhat.com> + * + * 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 + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ +#include <linux/cdev.h> +#include <linux/debugfs.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/list.h> +#include <linux/poll.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/virtio.h> +#include <linux/virtio_console.h> +#include <linux/wait.h> +#include <linux/workqueue.h> +#include "../tty/hvc/hvc_console.h" + +/* + * This is a global struct for storing common data for all the devices + * this driver handles. + * + * Mainly, it has a linked list for all the consoles in one place so + * that callbacks from hvc for get_chars(), put_chars() work properly + * across multiple devices and multiple ports per device. + */ +struct ports_driver_data { + /* Used for registering chardevs */ + struct class *class; + + /* Used for exporting per-port information to debugfs */ + struct dentry *debugfs_dir; + + /* List of all the devices we're handling */ + struct list_head portdevs; + + /* Number of devices this driver is handling */ + unsigned int index; + + /* + * This is used to keep track of the number of hvc consoles + * spawned by this driver. This number is given as the first + * argument to hvc_alloc(). To correctly map an initial + * console spawned via hvc_instantiate to the console being + * hooked up via hvc_alloc, we need to pass the same vtermno. + * + * We also just assume the first console being initialised was + * the first one that got used as the initial console. + */ + unsigned int next_vtermno; + + /* All the console devices handled by this driver */ + struct list_head consoles; +}; +static struct ports_driver_data pdrvdata; + +DEFINE_SPINLOCK(pdrvdata_lock); + +/* This struct holds information that's relevant only for console ports */ +struct console { + /* We'll place all consoles in a list in the pdrvdata struct */ + struct list_head list; + + /* The hvc device associated with this console port */ + struct hvc_struct *hvc; + + /* The size of the console */ + struct winsize ws; + + /* + * This number identifies the number that we used to register + * with hvc in hvc_instantiate() and hvc_alloc(); this is the + * number passed on by the hvc callbacks to us to + * differentiate between the other console ports handled by + * this driver + */ + u32 vtermno; +}; + +struct port_buffer { + char *buf; + + /* size of the buffer in *buf above */ + size_t size; + + /* used length of the buffer */ + size_t len; + /* offset in the buf from which to consume data */ + size_t offset; +}; + +/* + * This is a per-device struct that stores data common to all the + * ports for that device (vdev->priv). + */ +struct ports_device { + /* Next portdev in the list, head is in the pdrvdata struct */ + struct list_head list; + + /* + * Workqueue handlers where we process deferred work after + * notification + */ + struct work_struct control_work; + + struct list_head ports; + + /* To protect the list of ports */ + spinlock_t ports_lock; + + /* To protect the vq operations for the control channel */ + spinlock_t cvq_lock; + + /* The current config space is stored here */ + struct virtio_console_config config; + + /* The virtio device we're associated with */ + struct virtio_device *vdev; + + /* + * A couple of virtqueues for the control channel: one for + * guest->host transfers, one for host->guest transfers + */ + struct virtqueue *c_ivq, *c_ovq; + + /* Array of per-port IO virtqueues */ + struct virtqueue **in_vqs, **out_vqs; + + /* Used for numbering devices for sysfs and debugfs */ + unsigned int drv_index; + + /* Major number for this device. Ports will be created as minors. */ + int chr_major; +}; + +/* This struct holds the per-port data */ +struct port { + /* Next port in the list, head is in the ports_device */ + struct list_head list; + + /* Pointer to the parent virtio_console device */ + struct ports_device *portdev; + + /* The current buffer from which data has to be fed to readers */ + struct port_buffer *inbuf; + + /* + * To protect the operations on the in_vq associated with this + * port. Has to be a spinlock because it can be called from + * interrupt context (get_char()). + */ + spinlock_t inbuf_lock; + + /* Protect the operations on the out_vq. */ + spinlock_t outvq_lock; + + /* The IO vqs for this port */ + struct virtqueue *in_vq, *out_vq; + + /* File in the debugfs directory that exposes this port's information */ + struct dentry *debugfs_file; + + /* + * The entries in this struct will be valid if this port is + * hooked up to an hvc console + */ + struct console cons; + + /* Each port associates with a separate char device */ + struct cdev *cdev; + struct device *dev; + + /* Reference-counting to handle port hot-unplugs and file operations */ + struct kref kref; + + /* A waitqueue for poll() or blocking read operations */ + wait_queue_head_t waitqueue; + + /* The 'name' of the port that we expose via sysfs properties */ + char *name; + + /* We can notify apps of host connect / disconnect events via SIGIO */ + struct fasync_struct *async_queue; + + /* The 'id' to identify the port with the Host */ + u32 id; + + bool outvq_full; + + /* Is the host device open */ + bool host_connected; + + /* We should allow only one process to open a port */ + bool guest_connected; +}; + +/* This is the very early arch-specified put chars function. */ +static int (*early_put_chars)(u32, const char *, int); + +static struct port *find_port_by_vtermno(u32 vtermno) +{ + struct port *port; + struct console *cons; + unsigned long flags; + + spin_lock_irqsave(&pdrvdata_lock, flags); + list_for_each_entry(cons, &pdrvdata.consoles, list) { + if (cons->vtermno == vtermno) { + port = container_of(cons, struct port, cons); + goto out; + } + } + port = NULL; +out: + spin_unlock_irqrestore(&pdrvdata_lock, flags); + return port; +} + +static struct port *find_port_by_devt_in_portdev(struct ports_device *portdev, + dev_t dev) +{ + struct port *port; + unsigned long flags; + + spin_lock_irqsave(&portdev->ports_lock, flags); + list_for_each_entry(port, &portdev->ports, list) + if (port->cdev->dev == dev) + goto out; + port = NULL; +out: + spin_unlock_irqrestore(&portdev->ports_lock, flags); + + return port; +} + +static struct port *find_port_by_devt(dev_t dev) +{ + struct ports_device *portdev; + struct port *port; + unsigned long flags; + + spin_lock_irqsave(&pdrvdata_lock, flags); + list_for_each_entry(portdev, &pdrvdata.portdevs, list) { + port = find_port_by_devt_in_portdev(portdev, dev); + if (port) + goto out; + } + port = NULL; +out: + spin_unlock_irqrestore(&pdrvdata_lock, flags); + return port; +} + +static struct port *find_port_by_id(struct ports_device *portdev, u32 id) +{ + struct port *port; + unsigned long flags; + + spin_lock_irqsave(&portdev->ports_lock, flags); + list_for_each_entry(port, &portdev->ports, list) + if (port->id == id) + goto out; + port = NULL; +out: + spin_unlock_irqrestore(&portdev->ports_lock, flags); + + return port; +} + +static struct port *find_port_by_vq(struct ports_device *portdev, + struct virtqueue *vq) +{ + struct port *port; + unsigned long flags; + + spin_lock_irqsave(&portdev->ports_lock, flags); + list_for_each_entry(port, &portdev->ports, list) + if (port->in_vq == vq || port->out_vq == vq) + goto out; + port = NULL; +out: + spin_unlock_irqrestore(&portdev->ports_lock, flags); + return port; +} + +static bool is_console_port(struct port *port) +{ + if (port->cons.hvc) + return true; + return false; +} + +static inline bool use_multiport(struct ports_device *portdev) +{ + /* + * This condition can be true when put_chars is called from + * early_init + */ + if (!portdev->vdev) + return 0; + return portdev->vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT); +} + +static void free_buf(struct port_buffer *buf) +{ + kfree(buf->buf); + kfree(buf); +} + +static struct port_buffer *alloc_buf(size_t buf_size) +{ + struct port_buffer *buf; + + buf = kmalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) + goto fail; + buf->buf = kzalloc(buf_size, GFP_KERNEL); + if (!buf->buf) + goto free_buf; + buf->len = 0; + buf->offset = 0; + buf->size = buf_size; + return buf; + +free_buf: + kfree(buf); +fail: + return NULL; +} + +/* Callers should take appropriate locks */ +static void *get_inbuf(struct port *port) +{ + struct port_buffer *buf; + struct virtqueue *vq; + unsigned int len; + + vq = port->in_vq; + buf = virtqueue_get_buf(vq, &len); + if (buf) { + buf->len = len; + buf->offset = 0; + } + return buf; +} + +/* + * Create a scatter-gather list representing our input buffer and put + * it in the queue. + * + * Callers should take appropriate locks. + */ +static int add_inbuf(struct virtqueue *vq, struct port_buffer *buf) +{ + struct scatterlist sg[1]; + int ret; + + sg_init_one(sg, buf->buf, buf->size); + + ret = virtqueue_add_buf(vq, sg, 0, 1, buf); + virtqueue_kick(vq); + return ret; +} + +/* Discard any unread data this port has. Callers lockers. */ +static void discard_port_data(struct port *port) +{ + struct port_buffer *buf; + struct virtqueue *vq; + unsigned int len; + int ret; + + if (!port->portdev) { + /* Device has been unplugged. vqs are already gone. */ + return; + } + vq = port->in_vq; + if (port->inbuf) + buf = port->inbuf; + else + buf = virtqueue_get_buf(vq, &len); + + ret = 0; + while (buf) { + if (add_inbuf(vq, buf) < 0) { + ret++; + free_buf(buf); + } + buf = virtqueue_get_buf(vq, &len); + } + port->inbuf = NULL; + if (ret) + dev_warn(port->dev, "Errors adding %d buffers back to vq\n", + ret); +} + +static bool port_has_data(struct port *port) +{ + unsigned long flags; + bool ret; + + spin_lock_irqsave(&port->inbuf_lock, flags); + if (port->inbuf) { + ret = true; + goto out; + } + port->inbuf = get_inbuf(port); + if (port->inbuf) { + ret = true; + goto out; + } + ret = false; +out: + spin_unlock_irqrestore(&port->inbuf_lock, flags); + return ret; +} + +static ssize_t __send_control_msg(struct ports_device *portdev, u32 port_id, + unsigned int event, unsigned int value) +{ + struct scatterlist sg[1]; + struct virtio_console_control cpkt; + struct virtqueue *vq; + unsigned int len; + + if (!use_multiport(portdev)) + return 0; + + cpkt.id = port_id; + cpkt.event = event; + cpkt.value = value; + + vq = portdev->c_ovq; + + sg_init_one(sg, &cpkt, sizeof(cpkt)); + if (virtqueue_add_buf(vq, sg, 1, 0, &cpkt) >= 0) { + virtqueue_kick(vq); + while (!virtqueue_get_buf(vq, &len)) + cpu_relax(); + } + return 0; +} + +static ssize_t send_control_msg(struct port *port, unsigned int event, + unsigned int value) +{ + /* Did the port get unplugged before userspace closed it? */ + if (port->portdev) + return __send_control_msg(port->portdev, port->id, event, value); + return 0; +} + +/* Callers must take the port->outvq_lock */ +static void reclaim_consumed_buffers(struct port *port) +{ + void *buf; + unsigned int len; + + if (!port->portdev) { + /* Device has been unplugged. vqs are already gone. */ + return; + } + while ((buf = virtqueue_get_buf(port->out_vq, &len))) { + kfree(buf); + port->outvq_full = false; + } +} + +static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count, + bool nonblock) +{ + struct scatterlist sg[1]; + struct virtqueue *out_vq; + ssize_t ret; + unsigned long flags; + unsigned int len; + + out_vq = port->out_vq; + + spin_lock_irqsave(&port->outvq_lock, flags); + + reclaim_consumed_buffers(port); + + sg_init_one(sg, in_buf, in_count); + ret = virtqueue_add_buf(out_vq, sg, 1, 0, in_buf); + + /* Tell Host to go! */ + virtqueue_kick(out_vq); + + if (ret < 0) { + in_count = 0; + goto done; + } + + if (ret == 0) + port->outvq_full = true; + + if (nonblock) + goto done; + + /* + * Wait till the host acknowledges it pushed out the data we + * sent. This is done for data from the hvc_console; the tty + * operations are performed with spinlocks held so we can't + * sleep here. An alternative would be to copy the data to a + * buffer and relax the spinning requirement. The downside is + * we need to kmalloc a GFP_ATOMIC buffer each time the + * console driver writes something out. + */ + while (!virtqueue_get_buf(out_vq, &len)) + cpu_relax(); +done: + spin_unlock_irqrestore(&port->outvq_lock, flags); + /* + * We're expected to return the amount of data we wrote -- all + * of it + */ + return in_count; +} + +/* + * Give out the data that's requested from the buffer that we have + * queued up. + */ +static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count, + bool to_user) +{ + struct port_buffer *buf; + unsigned long flags; + + if (!out_count || !port_has_data(port)) + return 0; + + buf = port->inbuf; + out_count = min(out_count, buf->len - buf->offset); + + if (to_user) { + ssize_t ret; + + ret = copy_to_user(out_buf, buf->buf + buf->offset, out_count); + if (ret) + return -EFAULT; + } else { + memcpy(out_buf, buf->buf + buf->offset, out_count); + } + + buf->offset += out_count; + + if (buf->offset == buf->len) { + /* + * We're done using all the data in this buffer. + * Re-queue so that the Host can send us more data. + */ + spin_lock_irqsave(&port->inbuf_lock, flags); + port->inbuf = NULL; + + if (add_inbuf(port->in_vq, buf) < 0) + dev_warn(port->dev, "failed add_buf\n"); + + spin_unlock_irqrestore(&port->inbuf_lock, flags); + } + /* Return the number of bytes actually copied */ + return out_count; +} + +/* The condition that must be true for polling to end */ +static bool will_read_block(struct port *port) +{ + if (!port->guest_connected) { + /* Port got hot-unplugged. Let's exit. */ + return false; + } + return !port_has_data(port) && port->host_connected; +} + +static bool will_write_block(struct port *port) +{ + bool ret; + + if (!port->guest_connected) { + /* Port got hot-unplugged. Let's exit. */ + return false; + } + if (!port->host_connected) + return true; + + spin_lock_irq(&port->outvq_lock); + /* + * Check if the Host has consumed any buffers since we last + * sent data (this is only applicable for nonblocking ports). + */ + reclaim_consumed_buffers(port); + ret = port->outvq_full; + spin_unlock_irq(&port->outvq_lock); + + return ret; +} + +static ssize_t port_fops_read(struct file *filp, char __user *ubuf, + size_t count, loff_t *offp) +{ + struct port *port; + ssize_t ret; + + port = filp->private_data; + + if (!port_has_data(port)) { + /* + * If nothing's connected on the host just return 0 in + * case of list_empty; this tells the userspace app + * that there's no connection + */ + if (!port->host_connected) + return 0; + if (filp->f_flags & O_NONBLOCK) + return -EAGAIN; + + ret = wait_event_interruptible(port->waitqueue, + !will_read_block(port)); + if (ret < 0) + return ret; + } + /* Port got hot-unplugged. */ + if (!port->guest_connected) + return -ENODEV; + /* + * We could've received a disconnection message while we were + * waiting for more data. + * + * This check is not clubbed in the if() statement above as we + * might receive some data as well as the host could get + * disconnected after we got woken up from our wait. So we + * really want to give off whatever data we have and only then + * check for host_connected. + */ + if (!port_has_data(port) && !port->host_connected) + return 0; + + return fill_readbuf(port, ubuf, count, true); +} + +static ssize_t port_fops_write(struct file *filp, const char __user *ubuf, + size_t count, loff_t *offp) +{ + struct port *port; + char *buf; + ssize_t ret; + bool nonblock; + + /* Userspace could be out to fool us */ + if (!count) + return 0; + + port = filp->private_data; + + nonblock = filp->f_flags & O_NONBLOCK; + + if (will_write_block(port)) { + if (nonblock) + return -EAGAIN; + + ret = wait_event_interruptible(port->waitqueue, + !will_write_block(port)); + if (ret < 0) + return ret; + } + /* Port got hot-unplugged. */ + if (!port->guest_connected) + return -ENODEV; + + count = min((size_t)(32 * 1024), count); + + buf = kmalloc(count, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + ret = copy_from_user(buf, ubuf, count); + if (ret) { + ret = -EFAULT; + goto free_buf; + } + + /* + * We now ask send_buf() to not spin for generic ports -- we + * can re-use the same code path that non-blocking file + * descriptors take for blocking file descriptors since the + * wait is already done and we're certain the write will go + * through to the host. + */ + nonblock = true; + ret = send_buf(port, buf, count, nonblock); + + if (nonblock && ret > 0) + goto out; + +free_buf: + kfree(buf); +out: + return ret; +} + +static unsigned int port_fops_poll(struct file *filp, poll_table *wait) +{ + struct port *port; + unsigned int ret; + + port = filp->private_data; + poll_wait(filp, &port->waitqueue, wait); + + if (!port->guest_connected) { + /* Port got unplugged */ + return POLLHUP; + } + ret = 0; + if (!will_read_block(port)) + ret |= POLLIN | POLLRDNORM; + if (!will_write_block(port)) + ret |= POLLOUT; + if (!port->host_connected) + ret |= POLLHUP; + + return ret; +} + +static void remove_port(struct kref *kref); + +static int port_fops_release(struct inode *inode, struct file *filp) +{ + struct port *port; + + port = filp->private_data; + + /* Notify host of port being closed */ + send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0); + + spin_lock_irq(&port->inbuf_lock); + port->guest_connected = false; + + discard_port_data(port); + + spin_unlock_irq(&port->inbuf_lock); + + spin_lock_irq(&port->outvq_lock); + reclaim_consumed_buffers(port); + spin_unlock_irq(&port->outvq_lock); + + /* + * Locks aren't necessary here as a port can't be opened after + * unplug, and if a port isn't unplugged, a kref would already + * exist for the port. Plus, taking ports_lock here would + * create a dependency on other locks taken by functions + * inside remove_port if we're the last holder of the port, + * creating many problems. + */ + kref_put(&port->kref, remove_port); + + return 0; +} + +static int port_fops_open(struct inode *inode, struct file *filp) +{ + struct cdev *cdev = inode->i_cdev; + struct port *port; + int ret; + + port = find_port_by_devt(cdev->dev); + filp->private_data = port; + + /* Prevent against a port getting hot-unplugged at the same time */ + spin_lock_irq(&port->portdev->ports_lock); + kref_get(&port->kref); + spin_unlock_irq(&port->portdev->ports_lock); + + /* + * Don't allow opening of console port devices -- that's done + * via /dev/hvc + */ + if (is_console_port(port)) { + ret = -ENXIO; + goto out; + } + + /* Allow only one process to open a particular port at a time */ + spin_lock_irq(&port->inbuf_lock); + if (port->guest_connected) { + spin_unlock_irq(&port->inbuf_lock); + ret = -EMFILE; + goto out; + } + + port->guest_connected = true; + spin_unlock_irq(&port->inbuf_lock); + + spin_lock_irq(&port->outvq_lock); + /* + * There might be a chance that we missed reclaiming a few + * buffers in the window of the port getting previously closed + * and opening now. + */ + reclaim_consumed_buffers(port); + spin_unlock_irq(&port->outvq_lock); + + nonseekable_open(inode, filp); + + /* Notify host of port being opened */ + send_control_msg(filp->private_data, VIRTIO_CONSOLE_PORT_OPEN, 1); + + return 0; +out: + kref_put(&port->kref, remove_port); + return ret; +} + +static int port_fops_fasync(int fd, struct file *filp, int mode) +{ + struct port *port; + + port = filp->private_data; + return fasync_helper(fd, filp, mode, &port->async_queue); +} + +/* + * The file operations that we support: programs in the guest can open + * a console device, read from it, write to it, poll for data and + * close it. The devices are at + * /dev/vport<device number>p<port number> + */ +static const struct file_operations port_fops = { + .owner = THIS_MODULE, + .open = port_fops_open, + .read = port_fops_read, + .write = port_fops_write, + .poll = port_fops_poll, + .release = port_fops_release, + .fasync = port_fops_fasync, + .llseek = no_llseek, +}; + +/* + * 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 port *port; + + if (unlikely(early_put_chars)) + return early_put_chars(vtermno, buf, count); + + port = find_port_by_vtermno(vtermno); + if (!port) + return -EPIPE; + + return send_buf(port, (void *)buf, count, false); +} + +/* + * 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 get_chars(u32 vtermno, char *buf, int count) +{ + struct port *port; + + /* If we've not set up the port yet, we have no input to give. */ + if (unlikely(early_put_chars)) + return 0; + + port = find_port_by_vtermno(vtermno); + if (!port) + return -EPIPE; + + /* If we don't have an input queue yet, we can't get input. */ + BUG_ON(!port->in_vq); + + return fill_readbuf(port, buf, count, false); +} + +static void resize_console(struct port *port) +{ + struct virtio_device *vdev; + + /* The port could have been hot-unplugged */ + if (!port || !is_console_port(port)) + return; + + vdev = port->portdev->vdev; + if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE)) + hvc_resize(port->cons.hvc, port->cons.ws); +} + +/* We set the configuration at this point, since we now have a tty */ +static int notifier_add_vio(struct hvc_struct *hp, int data) +{ + struct port *port; + + port = find_port_by_vtermno(hp->vtermno); + if (!port) + return -EINVAL; + + hp->irq_requested = 1; + resize_console(port); + + return 0; +} + +static void notifier_del_vio(struct hvc_struct *hp, int data) +{ + hp->irq_requested = 0; +} + +/* The operations for console ports. */ +static const struct hv_ops hv_ops = { + .get_chars = get_chars, + .put_chars = put_chars, + .notifier_add = notifier_add_vio, + .notifier_del = notifier_del_vio, + .notifier_hangup = notifier_del_vio, +}; + +/* + * Console drivers are initialized very early so boot messages can go + * out, so we do things slightly differently from the generic virtio + * initialization of the net and block drivers. + * + * At this stage, the console is output-only. It's too early to set + * up a virtqueue, so we let the drivers do some boutique early-output + * thing. + */ +int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int)) +{ + early_put_chars = put_chars; + return hvc_instantiate(0, 0, &hv_ops); +} + +int init_port_console(struct port *port) +{ + int ret; + + /* + * The Host's telling us this port is a console port. Hook it + * up with an hvc console. + * + * To set up and manage our virtual console, we call + * hvc_alloc(). + * + * The first argument of hvc_alloc() is the virtual console + * number. The second argument is the parameter for the + * notification mechanism (like irq number). We currently + * leave this as zero, virtqueues have implicit notifications. + * + * The third argument is a "struct hv_ops" containing the + * put_chars() get_chars(), notifier_add() and notifier_del() + * pointers. The final argument is the output buffer size: we + * can do any size, so we put PAGE_SIZE here. + */ + port->cons.vtermno = pdrvdata.next_vtermno; + + port->cons.hvc = hvc_alloc(port->cons.vtermno, 0, &hv_ops, PAGE_SIZE); + if (IS_ERR(port->cons.hvc)) { + ret = PTR_ERR(port->cons.hvc); + dev_err(port->dev, + "error %d allocating hvc for port\n", ret); + port->cons.hvc = NULL; + return ret; + } + spin_lock_irq(&pdrvdata_lock); + pdrvdata.next_vtermno++; + list_add_tail(&port->cons.list, &pdrvdata.consoles); + spin_unlock_irq(&pdrvdata_lock); + port->guest_connected = true; + + /* + * Start using the new console output if this is the first + * console to come up. + */ + if (early_put_chars) + early_put_chars = NULL; + + /* Notify host of port being opened */ + send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 1); + + return 0; +} + +static ssize_t show_port_name(struct device *dev, + struct device_attribute *attr, char *buffer) +{ + struct port *port; + + port = dev_get_drvdata(dev); + + return sprintf(buffer, "%s\n", port->name); +} + +static DEVICE_ATTR(name, S_IRUGO, show_port_name, NULL); + +static struct attribute *port_sysfs_entries[] = { + &dev_attr_name.attr, + NULL +}; + +static struct attribute_group port_attribute_group = { + .name = NULL, /* put in device directory */ + .attrs = port_sysfs_entries, +}; + +static int debugfs_open(struct inode *inode, struct file *filp) +{ + filp->private_data = inode->i_private; + return 0; +} + +static ssize_t debugfs_read(struct file *filp, char __user *ubuf, + size_t count, loff_t *offp) +{ + struct port *port; + char *buf; + ssize_t ret, out_offset, out_count; + + out_count = 1024; + buf = kmalloc(out_count, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + port = filp->private_data; + out_offset = 0; + out_offset += snprintf(buf + out_offset, out_count, + "name: %s\n", port->name ? port->name : ""); + out_offset += snprintf(buf + out_offset, out_count - out_offset, + "guest_connected: %d\n", port->guest_connected); + out_offset += snprintf(buf + out_offset, out_count - out_offset, + "host_connected: %d\n", port->host_connected); + out_offset += snprintf(buf + out_offset, out_count - out_offset, + "outvq_full: %d\n", port->outvq_full); + out_offset += snprintf(buf + out_offset, out_count - out_offset, + "is_console: %s\n", + is_console_port(port) ? "yes" : "no"); + out_offset += snprintf(buf + out_offset, out_count - out_offset, + "console_vtermno: %u\n", port->cons.vtermno); + + ret = simple_read_from_buffer(ubuf, count, offp, buf, out_offset); + kfree(buf); + return ret; +} + +static const struct file_operations port_debugfs_ops = { + .owner = THIS_MODULE, + .open = debugfs_open, + .read = debugfs_read, +}; + +static void set_console_size(struct port *port, u16 rows, u16 cols) +{ + if (!port || !is_console_port(port)) + return; + + port->cons.ws.ws_row = rows; + port->cons.ws.ws_col = cols; +} + +static unsigned int fill_queue(struct virtqueue *vq, spinlock_t *lock) +{ + struct port_buffer *buf; + unsigned int nr_added_bufs; + int ret; + + nr_added_bufs = 0; + do { + buf = alloc_buf(PAGE_SIZE); + if (!buf) + break; + + spin_lock_irq(lock); + ret = add_inbuf(vq, buf); + if (ret < 0) { + spin_unlock_irq(lock); + free_buf(buf); + break; + } + nr_added_bufs++; + spin_unlock_irq(lock); + } while (ret > 0); + + return nr_added_bufs; +} + +static void send_sigio_to_port(struct port *port) +{ + if (port->async_queue && port->guest_connected) + kill_fasync(&port->async_queue, SIGIO, POLL_OUT); +} + +static int add_port(struct ports_device *portdev, u32 id) +{ + char debugfs_name[16]; + struct port *port; + struct port_buffer *buf; + dev_t devt; + unsigned int nr_added_bufs; + int err; + + port = kmalloc(sizeof(*port), GFP_KERNEL); + if (!port) { + err = -ENOMEM; + goto fail; + } + kref_init(&port->kref); + + port->portdev = portdev; + port->id = id; + + port->name = NULL; + port->inbuf = NULL; + port->cons.hvc = NULL; + port->async_queue = NULL; + + port->cons.ws.ws_row = port->cons.ws.ws_col = 0; + + port->host_connected = port->guest_connected = false; + + port->outvq_full = false; + + port->in_vq = portdev->in_vqs[port->id]; + port->out_vq = portdev->out_vqs[port->id]; + + port->cdev = cdev_alloc(); + if (!port->cdev) { + dev_err(&port->portdev->vdev->dev, "Error allocating cdev\n"); + err = -ENOMEM; + goto free_port; + } + port->cdev->ops = &port_fops; + + devt = MKDEV(portdev->chr_major, id); + err = cdev_add(port->cdev, devt, 1); + if (err < 0) { + dev_err(&port->portdev->vdev->dev, + "Error %d adding cdev for port %u\n", err, id); + goto free_cdev; + } + port->dev = device_create(pdrvdata.class, &port->portdev->vdev->dev, + devt, port, "vport%up%u", + port->portdev->drv_index, id); + if (IS_ERR(port->dev)) { + err = PTR_ERR(port->dev); + dev_err(&port->portdev->vdev->dev, + "Error %d creating device for port %u\n", + err, id); + goto free_cdev; + } + + spin_lock_init(&port->inbuf_lock); + spin_lock_init(&port->outvq_lock); + init_waitqueue_head(&port->waitqueue); + + /* Fill the in_vq with buffers so the host can send us data. */ + nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock); + if (!nr_added_bufs) { + dev_err(port->dev, "Error allocating inbufs\n"); + err = -ENOMEM; + goto free_device; + } + + /* + * If we're not using multiport support, this has to be a console port + */ + if (!use_multiport(port->portdev)) { + err = init_port_console(port); + if (err) + goto free_inbufs; + } + + spin_lock_irq(&portdev->ports_lock); + list_add_tail(&port->list, &port->portdev->ports); + spin_unlock_irq(&portdev->ports_lock); + + /* + * Tell the Host we're set so that it can send us various + * configuration parameters for this port (eg, port name, + * caching, whether this is a console port, etc.) + */ + send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1); + + if (pdrvdata.debugfs_dir) { + /* + * Finally, create the debugfs file that we can use to + * inspect a port's state at any time + */ + sprintf(debugfs_name, "vport%up%u", + port->portdev->drv_index, id); + port->debugfs_file = debugfs_create_file(debugfs_name, 0444, + pdrvdata.debugfs_dir, + port, + &port_debugfs_ops); + } + return 0; + +free_inbufs: + while ((buf = virtqueue_detach_unused_buf(port->in_vq))) + free_buf(buf); +free_device: + device_destroy(pdrvdata.class, port->dev->devt); +free_cdev: + cdev_del(port->cdev); +free_port: + kfree(port); +fail: + /* The host might want to notify management sw about port add failure */ + __send_control_msg(portdev, id, VIRTIO_CONSOLE_PORT_READY, 0); + return err; +} + +/* No users remain, remove all port-specific data. */ +static void remove_port(struct kref *kref) +{ + struct port *port; + + port = container_of(kref, struct port, kref); + + sysfs_remove_group(&port->dev->kobj, &port_attribute_group); + device_destroy(pdrvdata.class, port->dev->devt); + cdev_del(port->cdev); + + kfree(port->name); + + debugfs_remove(port->debugfs_file); + + kfree(port); +} + +/* + * Port got unplugged. Remove port from portdev's list and drop the + * kref reference. If no userspace has this port opened, it will + * result in immediate removal the port. + */ +static void unplug_port(struct port *port) +{ + struct port_buffer *buf; + + spin_lock_irq(&port->portdev->ports_lock); + list_del(&port->list); + spin_unlock_irq(&port->portdev->ports_lock); + + if (port->guest_connected) { + port->guest_connected = false; + port->host_connected = false; + wake_up_interruptible(&port->waitqueue); + + /* Let the app know the port is going down. */ + send_sigio_to_port(port); + } + + if (is_console_port(port)) { + spin_lock_irq(&pdrvdata_lock); + list_del(&port->cons.list); + spin_unlock_irq(&pdrvdata_lock); +#if 0 + /* + * hvc_remove() not called as removing one hvc port + * results in other hvc ports getting frozen. + * + * Once this is resolved in hvc, this functionality + * will be enabled. Till that is done, the -EPIPE + * return from get_chars() above will help + * hvc_console.c to clean up on ports we remove here. + */ + hvc_remove(port->cons.hvc); +#endif + } + + /* Remove unused data this port might have received. */ + discard_port_data(port); + + reclaim_consumed_buffers(port); + + /* Remove buffers we queued up for the Host to send us data in. */ + while ((buf = virtqueue_detach_unused_buf(port->in_vq))) + free_buf(buf); + + /* + * We should just assume the device itself has gone off -- + * else a close on an open port later will try to send out a + * control message. + */ + port->portdev = NULL; + + /* + * Locks around here are not necessary - a port can't be + * opened after we removed the port struct from ports_list + * above. + */ + kref_put(&port->kref, remove_port); +} + +/* Any private messages that the Host and Guest want to share */ +static void handle_control_message(struct ports_device *portdev, + struct port_buffer *buf) +{ + struct virtio_console_control *cpkt; + struct port *port; + size_t name_size; + int err; + + cpkt = (struct virtio_console_control *)(buf->buf + buf->offset); + + port = find_port_by_id(portdev, cpkt->id); + if (!port && cpkt->event != VIRTIO_CONSOLE_PORT_ADD) { + /* No valid header at start of buffer. Drop it. */ + dev_dbg(&portdev->vdev->dev, + "Invalid index %u in control packet\n", cpkt->id); + return; + } + + switch (cpkt->event) { + case VIRTIO_CONSOLE_PORT_ADD: + if (port) { + dev_dbg(&portdev->vdev->dev, + "Port %u already added\n", port->id); + send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1); + break; + } + if (cpkt->id >= portdev->config.max_nr_ports) { + dev_warn(&portdev->vdev->dev, + "Request for adding port with out-of-bound id %u, max. supported id: %u\n", + cpkt->id, portdev->config.max_nr_ports - 1); + break; + } + add_port(portdev, cpkt->id); + break; + case VIRTIO_CONSOLE_PORT_REMOVE: + unplug_port(port); + break; + case VIRTIO_CONSOLE_CONSOLE_PORT: + if (!cpkt->value) + break; + if (is_console_port(port)) + break; + + init_port_console(port); + /* + * Could remove the port here in case init fails - but + * have to notify the host first. + */ + break; + case VIRTIO_CONSOLE_RESIZE: { + struct { + __u16 rows; + __u16 cols; + } size; + + if (!is_console_port(port)) + break; + + memcpy(&size, buf->buf + buf->offset + sizeof(*cpkt), + sizeof(size)); + set_console_size(port, size.rows, size.cols); + + port->cons.hvc->irq_requested = 1; + resize_console(port); + break; + } + case VIRTIO_CONSOLE_PORT_OPEN: + port->host_connected = cpkt->value; + wake_up_interruptible(&port->waitqueue); + /* + * If the host port got closed and the host had any + * unconsumed buffers, we'll be able to reclaim them + * now. + */ + spin_lock_irq(&port->outvq_lock); + reclaim_consumed_buffers(port); + spin_unlock_irq(&port->outvq_lock); + + /* + * If the guest is connected, it'll be interested in + * knowing the host connection state changed. + */ + send_sigio_to_port(port); + break; + case VIRTIO_CONSOLE_PORT_NAME: + /* + * Skip the size of the header and the cpkt to get the size + * of the name that was sent + */ + name_size = buf->len - buf->offset - sizeof(*cpkt) + 1; + + port->name = kmalloc(name_size, GFP_KERNEL); + if (!port->name) { + dev_err(port->dev, + "Not enough space to store port name\n"); + break; + } + strncpy(port->name, buf->buf + buf->offset + sizeof(*cpkt), + name_size - 1); + port->name[name_size - 1] = 0; + + /* + * Since we only have one sysfs attribute, 'name', + * create it only if we have a name for the port. + */ + err = sysfs_create_group(&port->dev->kobj, + &port_attribute_group); + if (err) { + dev_err(port->dev, + "Error %d creating sysfs device attributes\n", + err); + } else { + /* + * Generate a udev event so that appropriate + * symlinks can be created based on udev + * rules. + */ + kobject_uevent(&port->dev->kobj, KOBJ_CHANGE); + } + break; + } +} + +static void control_work_handler(struct work_struct *work) +{ + struct ports_device *portdev; + struct virtqueue *vq; + struct port_buffer *buf; + unsigned int len; + + portdev = container_of(work, struct ports_device, control_work); + vq = portdev->c_ivq; + + spin_lock(&portdev->cvq_lock); + while ((buf = virtqueue_get_buf(vq, &len))) { + spin_unlock(&portdev->cvq_lock); + + buf->len = len; + buf->offset = 0; + + handle_control_message(portdev, buf); + + spin_lock(&portdev->cvq_lock); + if (add_inbuf(portdev->c_ivq, buf) < 0) { + dev_warn(&portdev->vdev->dev, + "Error adding buffer to queue\n"); + free_buf(buf); + } + } + spin_unlock(&portdev->cvq_lock); +} + +static void out_intr(struct virtqueue *vq) +{ + struct port *port; + + port = find_port_by_vq(vq->vdev->priv, vq); + if (!port) + return; + + wake_up_interruptible(&port->waitqueue); +} + +static void in_intr(struct virtqueue *vq) +{ + struct port *port; + unsigned long flags; + + port = find_port_by_vq(vq->vdev->priv, vq); + if (!port) + return; + + spin_lock_irqsave(&port->inbuf_lock, flags); + if (!port->inbuf) + port->inbuf = get_inbuf(port); + + /* + * Don't queue up data when port is closed. This condition + * can be reached when a console port is not yet connected (no + * tty is spawned) and the host sends out data to console + * ports. For generic serial ports, the host won't + * (shouldn't) send data till the guest is connected. + */ + if (!port->guest_connected) + discard_port_data(port); + + spin_unlock_irqrestore(&port->inbuf_lock, flags); + + wake_up_interruptible(&port->waitqueue); + + /* Send a SIGIO indicating new data in case the process asked for it */ + send_sigio_to_port(port); + + if (is_console_port(port) && hvc_poll(port->cons.hvc)) + hvc_kick(); +} + +static void control_intr(struct virtqueue *vq) +{ + struct ports_device *portdev; + + portdev = vq->vdev->priv; + schedule_work(&portdev->control_work); +} + +static void config_intr(struct virtio_device *vdev) +{ + struct ports_device *portdev; + + portdev = vdev->priv; + + if (!use_multiport(portdev)) { + struct port *port; + u16 rows, cols; + + vdev->config->get(vdev, + offsetof(struct virtio_console_config, cols), + &cols, sizeof(u16)); + vdev->config->get(vdev, + offsetof(struct virtio_console_config, rows), + &rows, sizeof(u16)); + + port = find_port_by_id(portdev, 0); + set_console_size(port, rows, cols); + + /* + * We'll use this way of resizing only for legacy + * support. For newer userspace + * (VIRTIO_CONSOLE_F_MULTPORT+), use control messages + * to indicate console size changes so that it can be + * done per-port. + */ + resize_console(port); + } +} + +static int init_vqs(struct ports_device *portdev) +{ + vq_callback_t **io_callbacks; + char **io_names; + struct virtqueue **vqs; + u32 i, j, nr_ports, nr_queues; + int err; + + nr_ports = portdev->config.max_nr_ports; + nr_queues = use_multiport(portdev) ? (nr_ports + 1) * 2 : 2; + + vqs = kmalloc(nr_queues * sizeof(struct virtqueue *), GFP_KERNEL); + io_callbacks = kmalloc(nr_queues * sizeof(vq_callback_t *), GFP_KERNEL); + io_names = kmalloc(nr_queues * sizeof(char *), GFP_KERNEL); + portdev->in_vqs = kmalloc(nr_ports * sizeof(struct virtqueue *), + GFP_KERNEL); + portdev->out_vqs = kmalloc(nr_ports * sizeof(struct virtqueue *), + GFP_KERNEL); + if (!vqs || !io_callbacks || !io_names || !portdev->in_vqs || + !portdev->out_vqs) { + err = -ENOMEM; + goto free; + } + + /* + * For backward compat (newer host but older guest), the host + * spawns a console port first and also inits the vqs for port + * 0 before others. + */ + j = 0; + io_callbacks[j] = in_intr; + io_callbacks[j + 1] = out_intr; + io_names[j] = "input"; + io_names[j + 1] = "output"; + j += 2; + + if (use_multiport(portdev)) { + io_callbacks[j] = control_intr; + io_callbacks[j + 1] = NULL; + io_names[j] = "control-i"; + io_names[j + 1] = "control-o"; + + for (i = 1; i < nr_ports; i++) { + j += 2; + io_callbacks[j] = in_intr; + io_callbacks[j + 1] = out_intr; + io_names[j] = "input"; + io_names[j + 1] = "output"; + } + } + /* Find the queues. */ + err = portdev->vdev->config->find_vqs(portdev->vdev, nr_queues, vqs, + io_callbacks, + (const char **)io_names); + if (err) + goto free; + + j = 0; + portdev->in_vqs[0] = vqs[0]; + portdev->out_vqs[0] = vqs[1]; + j += 2; + if (use_multiport(portdev)) { + portdev->c_ivq = vqs[j]; + portdev->c_ovq = vqs[j + 1]; + + for (i = 1; i < nr_ports; i++) { + j += 2; + portdev->in_vqs[i] = vqs[j]; + portdev->out_vqs[i] = vqs[j + 1]; + } + } + kfree(io_names); + kfree(io_callbacks); + kfree(vqs); + + return 0; + +free: + kfree(portdev->out_vqs); + kfree(portdev->in_vqs); + kfree(io_names); + kfree(io_callbacks); + kfree(vqs); + + return err; +} + +static const struct file_operations portdev_fops = { + .owner = THIS_MODULE, +}; + +/* + * Once we're further in boot, we get probed like any other virtio + * device. + * + * If the host also supports multiple console ports, we check the + * config space to see how many ports the host has spawned. We + * initialize each port found. + */ +static int __devinit virtcons_probe(struct virtio_device *vdev) +{ + struct ports_device *portdev; + int err; + bool multiport; + + portdev = kmalloc(sizeof(*portdev), GFP_KERNEL); + if (!portdev) { + err = -ENOMEM; + goto fail; + } + + /* Attach this portdev to this virtio_device, and vice-versa. */ + portdev->vdev = vdev; + vdev->priv = portdev; + + spin_lock_irq(&pdrvdata_lock); + portdev->drv_index = pdrvdata.index++; + spin_unlock_irq(&pdrvdata_lock); + + portdev->chr_major = register_chrdev(0, "virtio-portsdev", + &portdev_fops); + if (portdev->chr_major < 0) { + dev_err(&vdev->dev, + "Error %d registering chrdev for device %u\n", + portdev->chr_major, portdev->drv_index); + err = portdev->chr_major; + goto free; + } + + multiport = false; + portdev->config.max_nr_ports = 1; + if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) { + multiport = true; + vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT; + + vdev->config->get(vdev, offsetof(struct virtio_console_config, + max_nr_ports), + &portdev->config.max_nr_ports, + sizeof(portdev->config.max_nr_ports)); + } + + /* Let the Host know we support multiple ports.*/ + vdev->config->finalize_features(vdev); + + err = init_vqs(portdev); + if (err < 0) { + dev_err(&vdev->dev, "Error %d initializing vqs\n", err); + goto free_chrdev; + } + + spin_lock_init(&portdev->ports_lock); + INIT_LIST_HEAD(&portdev->ports); + + if (multiport) { + unsigned int nr_added_bufs; + + spin_lock_init(&portdev->cvq_lock); + INIT_WORK(&portdev->control_work, &control_work_handler); + + nr_added_bufs = fill_queue(portdev->c_ivq, &portdev->cvq_lock); + if (!nr_added_bufs) { + dev_err(&vdev->dev, + "Error allocating buffers for control queue\n"); + err = -ENOMEM; + goto free_vqs; + } + } else { + /* + * For backward compatibility: Create a console port + * if we're running on older host. + */ + add_port(portdev, 0); + } + + spin_lock_irq(&pdrvdata_lock); + list_add_tail(&portdev->list, &pdrvdata.portdevs); + spin_unlock_irq(&pdrvdata_lock); + + __send_control_msg(portdev, VIRTIO_CONSOLE_BAD_ID, + VIRTIO_CONSOLE_DEVICE_READY, 1); + return 0; + +free_vqs: + /* The host might want to notify mgmt sw about device add failure */ + __send_control_msg(portdev, VIRTIO_CONSOLE_BAD_ID, + VIRTIO_CONSOLE_DEVICE_READY, 0); + vdev->config->del_vqs(vdev); + kfree(portdev->in_vqs); + kfree(portdev->out_vqs); +free_chrdev: + unregister_chrdev(portdev->chr_major, "virtio-portsdev"); +free: + kfree(portdev); +fail: + return err; +} + +static void virtcons_remove(struct virtio_device *vdev) +{ + struct ports_device *portdev; + struct port *port, *port2; + + portdev = vdev->priv; + + spin_lock_irq(&pdrvdata_lock); + list_del(&portdev->list); + spin_unlock_irq(&pdrvdata_lock); + + /* Disable interrupts for vqs */ + vdev->config->reset(vdev); + /* Finish up work that's lined up */ + cancel_work_sync(&portdev->control_work); + + list_for_each_entry_safe(port, port2, &portdev->ports, list) + unplug_port(port); + + unregister_chrdev(portdev->chr_major, "virtio-portsdev"); + + /* + * When yanking out a device, we immediately lose the + * (device-side) queues. So there's no point in keeping the + * guest side around till we drop our final reference. This + * also means that any ports which are in an open state will + * have to just stop using the port, as the vqs are going + * away. + */ + if (use_multiport(portdev)) { + struct port_buffer *buf; + unsigned int len; + + while ((buf = virtqueue_get_buf(portdev->c_ivq, &len))) + free_buf(buf); + + while ((buf = virtqueue_detach_unused_buf(portdev->c_ivq))) + free_buf(buf); + } + + vdev->config->del_vqs(vdev); + kfree(portdev->in_vqs); + kfree(portdev->out_vqs); + + kfree(portdev); +} + +static struct virtio_device_id id_table[] = { + { VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID }, + { 0 }, +}; + +static unsigned int features[] = { + VIRTIO_CONSOLE_F_SIZE, + VIRTIO_CONSOLE_F_MULTIPORT, +}; + +static struct virtio_driver virtio_console = { + .feature_table = features, + .feature_table_size = ARRAY_SIZE(features), + .driver.name = KBUILD_MODNAME, + .driver.owner = THIS_MODULE, + .id_table = id_table, + .probe = virtcons_probe, + .remove = virtcons_remove, + .config_changed = config_intr, +}; + +static int __init init(void) +{ + int err; + + pdrvdata.class = class_create(THIS_MODULE, "virtio-ports"); + if (IS_ERR(pdrvdata.class)) { + err = PTR_ERR(pdrvdata.class); + pr_err("Error %d creating virtio-ports class\n", err); + return err; + } + + pdrvdata.debugfs_dir = debugfs_create_dir("virtio-ports", NULL); + if (!pdrvdata.debugfs_dir) { + pr_warning("Error %ld creating debugfs dir for virtio-ports\n", + PTR_ERR(pdrvdata.debugfs_dir)); + } + INIT_LIST_HEAD(&pdrvdata.consoles); + INIT_LIST_HEAD(&pdrvdata.portdevs); + + return register_virtio_driver(&virtio_console); +} + +static void __exit fini(void) +{ + unregister_virtio_driver(&virtio_console); + + class_destroy(pdrvdata.class); + if (pdrvdata.debugfs_dir) + debugfs_remove_recursive(pdrvdata.debugfs_dir); +} +module_init(init); +module_exit(fini); + +MODULE_DEVICE_TABLE(virtio, id_table); +MODULE_DESCRIPTION("Virtio console driver"); +MODULE_LICENSE("GPL"); |