OSCL-LXR linux-6.0.1/​drivers/​char/​virtio_console.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * 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>
  */
 #include <linux/cdev.h>
 #include <linux/debugfs.h>
 #include <linux/completion.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/freezer.h>
 #include <linux/fs.h>
 #include <linux/splice.h>
 #include <linux/pagemap.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 <linux/module.h>
 #include <linux/dma-mapping.h>
 #include "../tty/hvc/hvc_console.h"
 
 #define is_rproc_enabled IS_ENABLED(CONFIG_REMOTEPROC)
 #define VIRTCONS_MAX_PORTS 0x8000
 
 /*
  * 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;
 
     /*
      * 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 = { .next_vtermno = 1};
 
 static DEFINE_SPINLOCK(pdrvdata_lock);
 static DECLARE_COMPLETION(early_console_added);
 
 /* 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;
 
     /* DMA address of buffer */
     dma_addr_t dma;
 
     /* Device we got DMA memory from */
     struct device *dev;
 
     /* List of pending dma buffers to free */
     struct list_head list;
 
     /* If sgpages == 0 then buf is used */
     unsigned int sgpages;
 
     /* sg is used if spages > 0. sg must be the last in is struct */
     struct scatterlist sg[];
 };
 
 /*
  * 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 work_struct config_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 c_ivq_lock;
     spinlock_t c_ovq_lock;
 
     /* max. number of ports this device can hold */
     u32 max_nr_ports;
 
     /* 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;
 
     /*
      * A control packet buffer for guest->host requests, protected
      * by c_ovq_lock.
      */
     struct virtio_console_control cpkt;
 
     /* Array of per-port IO virtqueues */
     struct virtqueue **in_vqs, **out_vqs;
 
     /* Major number for this device.  Ports will be created as minors. */
     int chr_major;
 };
 
 struct port_stats {
     unsigned long bytes_sent, bytes_received, bytes_discarded;
 };
 
 /* 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;
 
     /*
      * Keep count of the bytes sent, received and discarded for
      * this port for accounting and debugging purposes.  These
      * counts are not reset across port open / close events.
      */
     struct port_stats stats;
 
     /*
      * 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) {
             kref_get(&port->kref);
             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 bool is_rproc_serial(const struct virtio_device *vdev)
 {
     return is_rproc_enabled && vdev->id.device == VIRTIO_ID_RPROC_SERIAL;
 }
 
 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 false;
     return __virtio_test_bit(portdev->vdev, VIRTIO_CONSOLE_F_MULTIPORT);
 }
 
 static DEFINE_SPINLOCK(dma_bufs_lock);
 static LIST_HEAD(pending_free_dma_bufs);
 
 static void free_buf(struct port_buffer *buf, bool can_sleep)
 {
     unsigned int i;
 
     for (i = 0; i < buf->sgpages; i++) {
         struct page *page = sg_page(&buf->sg[i]);
         if (!page)
             break;
         put_page(page);
     }
 
     if (!buf->dev) {
         kfree(buf->buf);
     } else if (is_rproc_enabled) {
         unsigned long flags;
 
         /* dma_free_coherent requires interrupts to be enabled. */
         if (!can_sleep) {
             /* queue up dma-buffers to be freed later */
             spin_lock_irqsave(&dma_bufs_lock, flags);
             list_add_tail(&buf->list, &pending_free_dma_bufs);
             spin_unlock_irqrestore(&dma_bufs_lock, flags);
             return;
         }
         dma_free_coherent(buf->dev, buf->size, buf->buf, buf->dma);
 
         /* Release device refcnt and allow it to be freed */
         put_device(buf->dev);
     }
 
     kfree(buf);
 }
 
 static void reclaim_dma_bufs(void)
 {
     unsigned long flags;
     struct port_buffer *buf, *tmp;
     LIST_HEAD(tmp_list);
 
     if (list_empty(&pending_free_dma_bufs))
         return;
 
     /* Create a copy of the pending_free_dma_bufs while holding the lock */
     spin_lock_irqsave(&dma_bufs_lock, flags);
     list_cut_position(&tmp_list, &pending_free_dma_bufs,
               pending_free_dma_bufs.prev);
     spin_unlock_irqrestore(&dma_bufs_lock, flags);
 
     /* Release the dma buffers, without irqs enabled */
     list_for_each_entry_safe(buf, tmp, &tmp_list, list) {
         list_del(&buf->list);
         free_buf(buf, true);
     }
 }
 
 static struct port_buffer *alloc_buf(struct virtio_device *vdev, size_t buf_size,
                      int pages)
 {
     struct port_buffer *buf;
 
     reclaim_dma_bufs();
 
     /*
      * Allocate buffer and the sg list. The sg list array is allocated
      * directly after the port_buffer struct.
      */
     buf = kmalloc(struct_size(buf, sg, pages), GFP_KERNEL);
     if (!buf)
         goto fail;
 
     buf->sgpages = pages;
     if (pages > 0) {
         buf->dev = NULL;
         buf->buf = NULL;
         return buf;
     }
 
     if (is_rproc_serial(vdev)) {
         /*
          * Allocate DMA memory from ancestor. When a virtio
          * device is created by remoteproc, the DMA memory is
          * associated with the parent device:
          * virtioY => remoteprocX#vdevYbuffer.
          */
         buf->dev = vdev->dev.parent;
         if (!buf->dev)
             goto free_buf;
 
         /* Increase device refcnt to avoid freeing it */
         get_device(buf->dev);
         buf->buf = dma_alloc_coherent(buf->dev, buf_size, &buf->dma,
                           GFP_KERNEL);
     } else {
         buf->dev = NULL;
         buf->buf = kmalloc(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 struct port_buffer *get_inbuf(struct port *port)
 {
     struct port_buffer *buf;
     unsigned int len;
 
     if (port->inbuf)
         return port->inbuf;
 
     buf = virtqueue_get_buf(port->in_vq, &len);
     if (buf) {
         buf->len = min_t(size_t, len, buf->size);
         buf->offset = 0;
         port->stats.bytes_received += len;
     }
     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_inbuf(vq, sg, 1, buf, GFP_ATOMIC);
     virtqueue_kick(vq);
     if (!ret)
         ret = vq->num_free;
     return ret;
 }
 
 /* Discard any unread data this port has. Callers lockers. */
 static void discard_port_data(struct port *port)
 {
     struct port_buffer *buf;
     unsigned int err;
 
     if (!port->portdev) {
         /* Device has been unplugged.  vqs are already gone. */
         return;
     }
     buf = get_inbuf(port);
 
     err = 0;
     while (buf) {
         port->stats.bytes_discarded += buf->len - buf->offset;
         if (add_inbuf(port->in_vq, buf) < 0) {
             err++;
             free_buf(buf, false);
         }
         port->inbuf = NULL;
         buf = get_inbuf(port);
     }
     if (err)
         dev_warn(port->dev, "Errors adding %d buffers back to vq\n",
              err);
 }
 
 static bool port_has_data(struct port *port)
 {
     unsigned long flags;
     bool ret;
 
     ret = false;
     spin_lock_irqsave(&port->inbuf_lock, flags);
     port->inbuf = get_inbuf(port);
     if (port->inbuf)
         ret = true;
 
     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 virtqueue *vq;
     unsigned int len;
 
     if (!use_multiport(portdev))
         return 0;
 
     vq = portdev->c_ovq;
 
     spin_lock(&portdev->c_ovq_lock);
 
     portdev->cpkt.id = cpu_to_virtio32(portdev->vdev, port_id);
     portdev->cpkt.event = cpu_to_virtio16(portdev->vdev, event);
     portdev->cpkt.value = cpu_to_virtio16(portdev->vdev, value);
 
     sg_init_one(sg, &portdev->cpkt, sizeof(struct virtio_console_control));
 
     if (virtqueue_add_outbuf(vq, sg, 1, &portdev->cpkt, GFP_ATOMIC) == 0) {
         virtqueue_kick(vq);
         while (!virtqueue_get_buf(vq, &len)
             && !virtqueue_is_broken(vq))
             cpu_relax();
     }
 
     spin_unlock(&portdev->c_ovq_lock);
     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)
 {
     struct port_buffer *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))) {
         free_buf(buf, false);
         port->outvq_full = false;
     }
 }
 
 static ssize_t __send_to_port(struct port *port, struct scatterlist *sg,
                   int nents, size_t in_count,
                   void *data, bool nonblock)
 {
     struct virtqueue *out_vq;
     int err;
     unsigned long flags;
     unsigned int len;
 
     out_vq = port->out_vq;
 
     spin_lock_irqsave(&port->outvq_lock, flags);
 
     reclaim_consumed_buffers(port);
 
     err = virtqueue_add_outbuf(out_vq, sg, nents, data, GFP_ATOMIC);
 
     /* Tell Host to go! */
     virtqueue_kick(out_vq);
 
     if (err) {
         in_count = 0;
         goto done;
     }
 
     if (out_vq->num_free == 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)
         && !virtqueue_is_broken(out_vq))
         cpu_relax();
 done:
     spin_unlock_irqrestore(&port->outvq_lock, flags);
 
     port->stats.bytes_sent += in_count;
     /*
      * 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 __user *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((__force char *)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;
 
     /* Port is hot-unplugged. */
     if (!port->guest_connected)
         return -ENODEV;
 
     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_freezable(port->waitqueue,
                        !will_read_block(port));
         if (ret < 0)
             return ret;
     }
     /* Port got hot-unplugged while we were waiting above. */
     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 int wait_port_writable(struct port *port, bool nonblock)
 {
     int ret;
 
     if (will_write_block(port)) {
         if (nonblock)
             return -EAGAIN;
 
         ret = wait_event_freezable(port->waitqueue,
                        !will_write_block(port));
         if (ret < 0)
             return ret;
     }
     /* Port got hot-unplugged. */
     if (!port->guest_connected)
         return -ENODEV;
 
     return 0;
 }
 
 static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
                    size_t count, loff_t *offp)
 {
     struct port *port;
     struct port_buffer *buf;
     ssize_t ret;
     bool nonblock;
     struct scatterlist sg[1];
 
     /* Userspace could be out to fool us */
     if (!count)
         return 0;
 
     port = filp->private_data;
 
     nonblock = filp->f_flags & O_NONBLOCK;
 
     ret = wait_port_writable(port, nonblock);
     if (ret < 0)
         return ret;
 
     count = min((size_t)(32 * 1024), count);
 
     buf = alloc_buf(port->portdev->vdev, count, 0);
     if (!buf)
         return -ENOMEM;
 
     ret = copy_from_user(buf->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;
     sg_init_one(sg, buf->buf, count);
     ret = __send_to_port(port, sg, 1, count, buf, nonblock);
 
     if (nonblock && ret > 0)
         goto out;
 
 free_buf:
     free_buf(buf, true);
 out:
     return ret;
 }
 
 struct sg_list {
     unsigned int n;
     unsigned int size;
     size_t len;
     struct scatterlist *sg;
 };
 
 static int pipe_to_sg(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
             struct splice_desc *sd)
 {
     struct sg_list *sgl = sd->u.data;
     unsigned int offset, len;
 
     if (sgl->n == sgl->size)
         return 0;
 
     /* Try lock this page */
     if (pipe_buf_try_steal(pipe, buf)) {
         /* Get reference and unlock page for moving */
         get_page(buf->page);
         unlock_page(buf->page);
 
         len = min(buf->len, sd->len);
         sg_set_page(&(sgl->sg[sgl->n]), buf->page, len, buf->offset);
     } else {
         /* Failback to copying a page */
         struct page *page = alloc_page(GFP_KERNEL);
         char *src;
 
         if (!page)
             return -ENOMEM;
 
         offset = sd->pos & ~PAGE_MASK;
 
         len = sd->len;
         if (len + offset > PAGE_SIZE)
             len = PAGE_SIZE - offset;
 
         src = kmap_atomic(buf->page);
         memcpy(page_address(page) + offset, src + buf->offset, len);
         kunmap_atomic(src);
 
         sg_set_page(&(sgl->sg[sgl->n]), page, len, offset);
     }
     sgl->n++;
     sgl->len += len;
 
     return len;
 }
 
 /* Faster zero-copy write by splicing */
 static ssize_t port_fops_splice_write(struct pipe_inode_info *pipe,
                       struct file *filp, loff_t *ppos,
                       size_t len, unsigned int flags)
 {
     struct port *port = filp->private_data;
     struct sg_list sgl;
     ssize_t ret;
     struct port_buffer *buf;
     struct splice_desc sd = {
         .total_len = len,
         .flags = flags,
         .pos = *ppos,
         .u.data = &sgl,
     };
     unsigned int occupancy;
 
     /*
      * Rproc_serial does not yet support splice. To support splice
      * pipe_to_sg() must allocate dma-buffers and copy content from
      * regular pages to dma pages. And alloc_buf and free_buf must
      * support allocating and freeing such a list of dma-buffers.
      */
     if (is_rproc_serial(port->out_vq->vdev))
         return -EINVAL;
 
     pipe_lock(pipe);
     ret = 0;
     if (pipe_empty(pipe->head, pipe->tail))
         goto error_out;
 
     ret = wait_port_writable(port, filp->f_flags & O_NONBLOCK);
     if (ret < 0)
         goto error_out;
 
     occupancy = pipe_occupancy(pipe->head, pipe->tail);
     buf = alloc_buf(port->portdev->vdev, 0, occupancy);
 
     if (!buf) {
         ret = -ENOMEM;
         goto error_out;
     }
 
     sgl.n = 0;
     sgl.len = 0;
     sgl.size = occupancy;
     sgl.sg = buf->sg;
     sg_init_table(sgl.sg, sgl.size);
     ret = __splice_from_pipe(pipe, &sd, pipe_to_sg);
     pipe_unlock(pipe);
     if (likely(ret > 0))
         ret = __send_to_port(port, buf->sg, sgl.n, sgl.len, buf, true);
 
     if (unlikely(ret <= 0))
         free_buf(buf, true);
     return ret;
 
 error_out:
     pipe_unlock(pipe);
     return ret;
 }
 
 static __poll_t port_fops_poll(struct file *filp, poll_table *wait)
 {
     struct port *port;
     __poll_t ret;
 
     port = filp->private_data;
     poll_wait(filp, &port->waitqueue, wait);
 
     if (!port->guest_connected) {
         /* Port got unplugged */
         return EPOLLHUP;
     }
     ret = 0;
     if (!will_read_block(port))
         ret |= EPOLLIN | EPOLLRDNORM;
     if (!will_write_block(port))
         ret |= EPOLLOUT;
     if (!port->host_connected)
         ret |= EPOLLHUP;
 
     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);
 
     reclaim_dma_bufs();
     /*
      * 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;
 
     /* We get the port with a kref here */
     port = find_port_by_devt(cdev->dev);
     if (!port) {
         /* Port was unplugged before we could proceed */
         return -ENXIO;
     }
     filp->private_data = port;
 
     /*
      * 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 = -EBUSY;
         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,
     .splice_write = port_fops_splice_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.
  */
 static int put_chars(u32 vtermno, const char *buf, int count)
 {
     struct port *port;
     struct scatterlist sg[1];
     void *data;
     int ret;
 
     if (unlikely(early_put_chars))
         return early_put_chars(vtermno, buf, count);
 
     port = find_port_by_vtermno(vtermno);
     if (!port)
         return -EPIPE;
 
     data = kmemdup(buf, count, GFP_ATOMIC);
     if (!data)
         return -ENOMEM;
 
     sg_init_one(sg, data, count);
     ret = __send_to_port(port, sg, 1, count, data, false);
     kfree(data);
     return ret;
 }
 
 /*
  * 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, (__force char __user *)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;
 
     /* Don't test F_SIZE at all if we're rproc: not a valid feature! */
     if (!is_rproc_serial(vdev) &&
         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);
 }
 
 static 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 const struct attribute_group port_attribute_group = {
     .name = NULL,       /* put in device directory */
     .attrs = port_sysfs_entries,
 };
 
 static int port_debugfs_show(struct seq_file *s, void *data)
 {
     struct port *port = s->private;
 
     seq_printf(s, "name: %s\n", port->name ? port->name : "");
     seq_printf(s, "guest_connected: %d\n", port->guest_connected);
     seq_printf(s, "host_connected: %d\n", port->host_connected);
     seq_printf(s, "outvq_full: %d\n", port->outvq_full);
     seq_printf(s, "bytes_sent: %lu\n", port->stats.bytes_sent);
     seq_printf(s, "bytes_received: %lu\n", port->stats.bytes_received);
     seq_printf(s, "bytes_discarded: %lu\n", port->stats.bytes_discarded);
     seq_printf(s, "is_console: %s\n",
            is_console_port(port) ? "yes" : "no");
     seq_printf(s, "console_vtermno: %u\n", port->cons.vtermno);
 
     return 0;
 }
 
 DEFINE_SHOW_ATTRIBUTE(port_debugfs);
 
 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 int fill_queue(struct virtqueue *vq, spinlock_t *lock)
 {
     struct port_buffer *buf;
     int nr_added_bufs;
     int ret;
 
     nr_added_bufs = 0;
     do {
         buf = alloc_buf(vq->vdev, PAGE_SIZE, 0);
         if (!buf)
             return -ENOMEM;
 
         spin_lock_irq(lock);
         ret = add_inbuf(vq, buf);
         if (ret < 0) {
             spin_unlock_irq(lock);
             free_buf(buf, true);
             return ret;
         }
         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;
     dev_t devt;
     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->cons.vtermno = 0;
 
     port->host_connected = port->guest_connected = false;
     port->stats = (struct port_stats) { 0 };
 
     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->vdev->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);
 
     /* We can safely ignore ENOSPC because it means
      * the queue already has buffers. Buffers are removed
      * only by virtcons_remove(), not by unplug_port()
      */
     err = fill_queue(port->in_vq, &port->inbuf_lock);
     if (err < 0 && err != -ENOSPC) {
         dev_err(port->dev, "Error allocating inbufs\n");
         goto free_device;
     }
 
     if (is_rproc_serial(port->portdev->vdev))
         /*
          * For rproc_serial assume remote processor is connected.
          * rproc_serial does not want the console port, only
          * the generic port implementation.
          */
         port->host_connected = true;
     else if (!use_multiport(port->portdev)) {
         /*
          * If we're not using multiport support,
          * this has to be a console port.
          */
         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);
 
     /*
      * Finally, create the debugfs file that we can use to
      * inspect a port's state at any time
      */
     snprintf(debugfs_name, sizeof(debugfs_name), "vport%up%u",
          port->portdev->vdev->index, id);
     port->debugfs_file = debugfs_create_file(debugfs_name, 0444,
                          pdrvdata.debugfs_dir,
                          port, &port_debugfs_fops);
     return 0;
 
 free_inbufs:
 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);
 
     kfree(port);
 }
 
 static void remove_port_data(struct port *port)
 {
     spin_lock_irq(&port->inbuf_lock);
     /* Remove unused data this port might have received. */
     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);
 }
 
 /*
  * 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)
 {
     spin_lock_irq(&port->portdev->ports_lock);
     list_del(&port->list);
     spin_unlock_irq(&port->portdev->ports_lock);
 
     spin_lock_irq(&port->inbuf_lock);
     if (port->guest_connected) {
         /* Let the app know the port is going down. */
         send_sigio_to_port(port);
 
         /* Do this after sigio is actually sent */
         port->guest_connected = false;
         port->host_connected = false;
 
         wake_up_interruptible(&port->waitqueue);
     }
     spin_unlock_irq(&port->inbuf_lock);
 
     if (is_console_port(port)) {
         spin_lock_irq(&pdrvdata_lock);
         list_del(&port->cons.list);
         spin_unlock_irq(&pdrvdata_lock);
         hvc_remove(port->cons.hvc);
     }
 
     remove_port_data(port);
 
     /*
      * 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;
 
     sysfs_remove_group(&port->dev->kobj, &port_attribute_group);
     device_destroy(pdrvdata.class, port->dev->devt);
     cdev_del(port->cdev);
 
     debugfs_remove(port->debugfs_file);
     kfree(port->name);
 
     /*
      * 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 virtio_device *vdev,
                    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, virtio32_to_cpu(vdev, cpkt->id));
     if (!port &&
         cpkt->event != cpu_to_virtio16(vdev, 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 (virtio16_to_cpu(vdev, 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 (virtio32_to_cpu(vdev, cpkt->id) >=
             portdev->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->max_nr_ports - 1);
             break;
         }
         add_port(portdev, virtio32_to_cpu(vdev, 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);
         complete(&early_console_added);
         /*
          * 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 = virtio16_to_cpu(vdev, 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.
          */
         spin_lock_irq(&port->inbuf_lock);
         send_sigio_to_port(port);
         spin_unlock_irq(&port->inbuf_lock);
         break;
     case VIRTIO_CONSOLE_PORT_NAME:
         /*
          * If we woke up after hibernation, we can get this
          * again.  Skip it in that case.
          */
         if (port->name)
             break;
 
         /*
          * 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->c_ivq_lock);
     while ((buf = virtqueue_get_buf(vq, &len))) {
         spin_unlock(&portdev->c_ivq_lock);
 
         buf->len = min_t(size_t, len, buf->size);
         buf->offset = 0;
 
         handle_control_message(vq->vdev, portdev, buf);
 
         spin_lock(&portdev->c_ivq_lock);
         if (add_inbuf(portdev->c_ivq, buf) < 0) {
             dev_warn(&portdev->vdev->dev,
                  "Error adding buffer to queue\n");
             free_buf(buf, false);
         }
     }
     spin_unlock(&portdev->c_ivq_lock);
 }
 
 static void flush_bufs(struct virtqueue *vq, bool can_sleep)
 {
     struct port_buffer *buf;
     unsigned int len;
 
     while ((buf = virtqueue_get_buf(vq, &len)))
         free_buf(buf, can_sleep);
 }
 
 static void out_intr(struct virtqueue *vq)
 {
     struct port *port;
 
     port = find_port_by_vq(vq->vdev->priv, vq);
     if (!port) {
         flush_bufs(vq, false);
         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) {
         flush_bufs(vq, false);
         return;
     }
 
     spin_lock_irqsave(&port->inbuf_lock, flags);
     port->inbuf = get_inbuf(port);
 
     /*
      * Normally the port should not accept data when the port is
      * closed. For generic serial ports, the host won't (shouldn't)
      * send data till the guest is connected. But this condition
      * can be reached when a console port is not yet connected (no
      * tty is spawned) and the other side sends out data over the
      * vring, or when a remote devices start sending data before
      * the ports are opened.
      *
      * A generic serial port will discard data if not connected,
      * while console ports and rproc-serial ports accepts data at
      * any time. rproc-serial is initiated with guest_connected to
      * false because port_fops_open expects this. Console ports are
      * hooked up with an HVC console and is initialized with
      * guest_connected to true.
      */
 
     if (!port->guest_connected && !is_rproc_serial(port->portdev->vdev))
         discard_port_data(port);
 
     /* Send a SIGIO indicating new data in case the process asked for it */
     send_sigio_to_port(port);
 
     spin_unlock_irqrestore(&port->inbuf_lock, flags);
 
     wake_up_interruptible(&port->waitqueue);
 
     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))
         schedule_work(&portdev->config_work);
 }
 
 static void config_work_handler(struct work_struct *work)
 {
     struct ports_device *portdev;
 
     portdev = container_of(work, struct ports_device, config_work);
     if (!use_multiport(portdev)) {
         struct virtio_device *vdev;
         struct port *port;
         u16 rows, cols;
 
         vdev = portdev->vdev;
         virtio_cread(vdev, struct virtio_console_config, cols, &cols);
         virtio_cread(vdev, struct virtio_console_config, rows, &rows);
 
         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->max_nr_ports;
     nr_queues = use_multiport(portdev) ? (nr_ports + 1) * 2 : 2;
 
     vqs = kmalloc_array(nr_queues, sizeof(struct virtqueue *), GFP_KERNEL);
     io_callbacks = kmalloc_array(nr_queues, sizeof(vq_callback_t *),
                      GFP_KERNEL);
     io_names = kmalloc_array(nr_queues, sizeof(char *), GFP_KERNEL);
     portdev->in_vqs = kmalloc_array(nr_ports, sizeof(struct virtqueue *),
                     GFP_KERNEL);
     portdev->out_vqs = kmalloc_array(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 = virtio_find_vqs(portdev->vdev, nr_queues, vqs,
                   io_callbacks,
                   (const char **)io_names, NULL);
     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,
 };
 
 static void remove_vqs(struct ports_device *portdev)
 {
     struct virtqueue *vq;
 
     virtio_device_for_each_vq(portdev->vdev, vq) {
         struct port_buffer *buf;
 
         flush_bufs(vq, true);
         while ((buf = virtqueue_detach_unused_buf(vq)))
             free_buf(buf, true);
     }
     portdev->vdev->config->del_vqs(portdev->vdev);
     kfree(portdev->in_vqs);
     kfree(portdev->out_vqs);
 }
 
 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);
 
     /* Device is going away, exit any polling for buffers */
     virtio_break_device(vdev);
     if (use_multiport(portdev))
         flush_work(&portdev->control_work);
     else
         flush_work(&portdev->config_work);
 
     /* Disable interrupts for vqs */
     virtio_reset_device(vdev);
     /* Finish up work that's lined up */
     if (use_multiport(portdev))
         cancel_work_sync(&portdev->control_work);
     else
         cancel_work_sync(&portdev->config_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.
      */
     remove_vqs(portdev);
     kfree(portdev);
 }
 
 /*
  * 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 virtcons_probe(struct virtio_device *vdev)
 {
     struct ports_device *portdev;
     int err;
     bool multiport;
     bool early = early_put_chars != NULL;
 
     /* We only need a config space if features are offered */
     if (!vdev->config->get &&
         (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE)
          || virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT))) {
         dev_err(&vdev->dev, "%s failure: config access disabled\n",
             __func__);
         return -EINVAL;
     }
 
     /* Ensure to read early_put_chars now */
     barrier();
 
     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;
 
     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, vdev->index);
         err = portdev->chr_major;
         goto free;
     }
 
     multiport = false;
     portdev->max_nr_ports = 1;
 
     /* Don't test MULTIPORT at all if we're rproc: not a valid feature! */
     if (!is_rproc_serial(vdev) &&
         virtio_cread_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
                  struct virtio_console_config, max_nr_ports,
                  &portdev->max_nr_ports) == 0) {
         if (portdev->max_nr_ports == 0 ||
             portdev->max_nr_ports > VIRTCONS_MAX_PORTS) {
             dev_err(&vdev->dev,
                 "Invalidate max_nr_ports %d",
                 portdev->max_nr_ports);
             err = -EINVAL;
             goto free;
         }
         multiport = true;
     }
 
     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);
     INIT_LIST_HEAD(&portdev->list);
 
     virtio_device_ready(portdev->vdev);
 
     INIT_WORK(&portdev->config_work, &config_work_handler);
     INIT_WORK(&portdev->control_work, &control_work_handler);
 
     if (multiport) {
         spin_lock_init(&portdev->c_ivq_lock);
         spin_lock_init(&portdev->c_ovq_lock);
 
         err = fill_queue(portdev->c_ivq, &portdev->c_ivq_lock);
         if (err < 0) {
             dev_err(&vdev->dev,
                 "Error allocating buffers for control queue\n");
             /*
              * 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);
             /* Device was functional: we need full cleanup. */
             virtcons_remove(vdev);
             return err;
         }
     } 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);
 
     /*
      * If there was an early virtio console, assume that there are no
      * other consoles. We need to wait until the hvc_alloc matches the
      * hvc_instantiate, otherwise tty_open will complain, resulting in
      * a "Warning: unable to open an initial console" boot failure.
      * Without multiport this is done in add_port above. With multiport
      * this might take some host<->guest communication - thus we have to
      * wait.
      */
     if (multiport && early)
         wait_for_completion(&early_console_added);
 
     return 0;
 
 free_chrdev:
     unregister_chrdev(portdev->chr_major, "virtio-portsdev");
 free:
     kfree(portdev);
 fail:
     return err;
 }
 
 static const struct virtio_device_id id_table[] = {
     { VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
     { 0 },
 };
 MODULE_DEVICE_TABLE(virtio, id_table);
 
 static const unsigned int features[] = {
     VIRTIO_CONSOLE_F_SIZE,
     VIRTIO_CONSOLE_F_MULTIPORT,
 };
 
 static const struct virtio_device_id rproc_serial_id_table[] = {
 #if IS_ENABLED(CONFIG_REMOTEPROC)
     { VIRTIO_ID_RPROC_SERIAL, VIRTIO_DEV_ANY_ID },
 #endif
     { 0 },
 };
 MODULE_DEVICE_TABLE(virtio, rproc_serial_id_table);
 
 static const unsigned int rproc_serial_features[] = {
 };
 
 #ifdef CONFIG_PM_SLEEP
 static int virtcons_freeze(struct virtio_device *vdev)
 {
     struct ports_device *portdev;
     struct port *port;
 
     portdev = vdev->priv;
 
     virtio_reset_device(vdev);
 
     if (use_multiport(portdev))
         virtqueue_disable_cb(portdev->c_ivq);
     cancel_work_sync(&portdev->control_work);
     cancel_work_sync(&portdev->config_work);
     /*
      * Once more: if control_work_handler() was running, it would
      * enable the cb as the last step.
      */
     if (use_multiport(portdev))
         virtqueue_disable_cb(portdev->c_ivq);
 
     list_for_each_entry(port, &portdev->ports, list) {
         virtqueue_disable_cb(port->in_vq);
         virtqueue_disable_cb(port->out_vq);
         /*
          * We'll ask the host later if the new invocation has
          * the port opened or closed.
          */
         port->host_connected = false;
         remove_port_data(port);
     }
     remove_vqs(portdev);
 
     return 0;
 }
 
 static int virtcons_restore(struct virtio_device *vdev)
 {
     struct ports_device *portdev;
     struct port *port;
     int ret;
 
     portdev = vdev->priv;
 
     ret = init_vqs(portdev);
     if (ret)
         return ret;
 
     virtio_device_ready(portdev->vdev);
 
     if (use_multiport(portdev))
         fill_queue(portdev->c_ivq, &portdev->c_ivq_lock);
 
     list_for_each_entry(port, &portdev->ports, list) {
         port->in_vq = portdev->in_vqs[port->id];
         port->out_vq = portdev->out_vqs[port->id];
 
         fill_queue(port->in_vq, &port->inbuf_lock);
 
         /* Get port open/close status on the host */
         send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
 
         /*
          * If a port was open at the time of suspending, we
          * have to let the host know that it's still open.
          */
         if (port->guest_connected)
             send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
     }
     return 0;
 }
 #endif
 
 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,
 #ifdef CONFIG_PM_SLEEP
     .freeze =   virtcons_freeze,
     .restore =  virtcons_restore,
 #endif
 };
 
 static struct virtio_driver virtio_rproc_serial = {
     .feature_table = rproc_serial_features,
     .feature_table_size = ARRAY_SIZE(rproc_serial_features),
     .driver.name =  "virtio_rproc_serial",
     .driver.owner = THIS_MODULE,
     .id_table = rproc_serial_id_table,
     .probe =    virtcons_probe,
     .remove =   virtcons_remove,
 };
 
 static int __init virtio_console_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);
     INIT_LIST_HEAD(&pdrvdata.consoles);
     INIT_LIST_HEAD(&pdrvdata.portdevs);
 
     err = register_virtio_driver(&virtio_console);
     if (err < 0) {
         pr_err("Error %d registering virtio driver\n", err);
         goto free;
     }
     err = register_virtio_driver(&virtio_rproc_serial);
     if (err < 0) {
         pr_err("Error %d registering virtio rproc serial driver\n",
                err);
         goto unregister;
     }
     return 0;
 unregister:
     unregister_virtio_driver(&virtio_console);
 free:
     debugfs_remove_recursive(pdrvdata.debugfs_dir);
     class_destroy(pdrvdata.class);
     return err;
 }
 
 static void __exit virtio_console_fini(void)
 {
     reclaim_dma_bufs();
 
     unregister_virtio_driver(&virtio_console);
     unregister_virtio_driver(&virtio_rproc_serial);
 
     class_destroy(pdrvdata.class);
     debugfs_remove_recursive(pdrvdata.debugfs_dir);
 }
 module_init(virtio_console_init);
 module_exit(virtio_console_fini);
 
 MODULE_DESCRIPTION("Virtio console driver");
 MODULE_LICENSE("GPL");

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