net/9p/trans_virtio.c - kernel/msm-4.9 - Gitiles

 /*
  * The Guest 9p transport driver
  *
  * This is a trivial pipe-based transport driver based on the lguest console
  * code: we use lguest's DMA mechanism to send bytes out, and register a
  * DMA buffer to receive bytes in.  It is assumed to be present and available
  * from the very beginning of boot.
  *
  * This may be have been done by just instaniating another HVC console,
  * but HVC's blocksize of 16 bytes is annoying and painful to performance.
  *
  * A more efficient transport could be built based on the virtio block driver
  * but it requires some changes in the 9p transport model (which are in
  * progress)
  *
  */
 /*
  *  Copyright (C) 2007 Eric Van Hensbergen, IBM Corporation
  *
  *  Based on virtio console driver
  *  Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2
  *  as published by the Free Software Foundation.
  *
  *  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:
  *  Free Software Foundation
  *  51 Franklin Street, Fifth Floor
  *  Boston, MA  02111-1301  USA
  *
  */

 #include <linux/in.h>
 #include <linux/module.h>
 #include <linux/net.h>
 #include <linux/ipv6.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/un.h>
 #include <linux/uaccess.h>
 #include <linux/inet.h>
 #include <linux/idr.h>
 #include <linux/file.h>
 #include <net/9p/9p.h>
 #include <linux/parser.h>
 #include <net/9p/transport.h>
 #include <linux/scatterlist.h>
 #include <linux/virtio.h>
 #include <linux/virtio_9p.h>

 /* a single mutex to manage channel initialization and attachment */
 static DECLARE_MUTEX(virtio_9p_lock);
 /* global which tracks highest initialized channel */
 static int chan_index;

 /* We keep all per-channel information in a structure.
  * This structure is allocated within the devices dev->mem space.
  * A pointer to the structure will get put in the transport private.
  */
 static struct virtio_chan {
 	bool initialized;		/* channel is initialized */
 	bool inuse;			/* channel is in use */

 	struct virtqueue *in_vq, *out_vq;
 	struct virtio_device *vdev;

 	/* This is our input buffer, and how much data is left in it. */
 	unsigned int in_len;
 	char *in, *inbuf;

 	wait_queue_head_t wq;		/* waitq for buffer */
 } channels[MAX_9P_CHAN];

 /* How many bytes left in this page. */
 static unsigned int rest_of_page(void *data)
 {
 	return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
 }

 static int p9_virtio_write(struct p9_trans *trans, void *buf, int count)
 {
 	struct virtio_chan *chan = (struct virtio_chan *) trans->priv;
 	struct virtqueue *out_vq = chan->out_vq;
 	struct scatterlist sg[1];
 	unsigned int len;

 	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio write (%d)\n", count);

 	/* keep it simple - make sure we don't overflow a page */
 	if (rest_of_page(buf) < count)
 		count = rest_of_page(buf);

 	sg_init_one(sg, buf, count);

 	/* add_buf wants a token to identify this buffer: we hand it any
 	 * non-NULL pointer, since there's only ever one buffer. */
 	if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) == 0) {
 		/* Tell Host to go! */
 		out_vq->vq_ops->kick(out_vq);
 		/* Chill out until it's done with the buffer. */
 		while (!out_vq->vq_ops->get_buf(out_vq, &len))
 			cpu_relax();
 	}

 	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio wrote (%d)\n", count);

 	/* We're expected to return the amount of data we wrote: all of it. */
 	return count;
 }

 /* Create a scatter-gather list representing our input buffer and put it in the
  * queue. */
 static void add_inbuf(struct virtio_chan *chan)
 {
 	struct scatterlist sg[1];

 	sg_init_one(sg, chan->inbuf, PAGE_SIZE);

 	/* We should always be able to add one buffer to an empty queue. */
 	if (chan->in_vq->vq_ops->add_buf(chan->in_vq, sg, 0, 1, chan->inbuf))
 		BUG();
 	chan->in_vq->vq_ops->kick(chan->in_vq);
 }

 static int p9_virtio_read(struct p9_trans *trans, void *buf, int count)
 {
 	struct virtio_chan *chan = (struct virtio_chan *) trans->priv;
 	struct virtqueue *in_vq = chan->in_vq;

 	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio read (%d)\n", count);

 	/* If we don't have an input queue yet, we can't get input. */
 	BUG_ON(!in_vq);

 	/* No buffer?  Try to get one. */
 	if (!chan->in_len) {
 		chan->in = in_vq->vq_ops->get_buf(in_vq, &chan->in_len);
 		if (!chan->in)
 			return 0;
 	}

 	/* You want more than we have to give?  Well, try wanting less! */
 	if (chan->in_len < count)
 		count = chan->in_len;

 	/* Copy across to their buffer and increment offset. */
 	memcpy(buf, chan->in, count);
 	chan->in += count;
 	chan->in_len -= count;

 	/* Finished?  Re-register buffer so Host will use it again. */
 	if (chan->in_len == 0)
 		add_inbuf(chan);

 	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio finished read (%d)\n",
 									count);

 	return count;
 }

 /* The poll function is used by 9p transports to determine if there
  * is there is activity available on a particular channel.  In our case
  * we use it to wait for a callback from the input routines.
  */
 static unsigned int
 p9_virtio_poll(struct p9_trans *trans, struct poll_table_struct *pt)
 {
 	struct virtio_chan *chan = (struct virtio_chan *)trans->priv;
 	struct virtqueue *in_vq = chan->in_vq;
 	int ret = POLLOUT; /* we can always handle more output */

 	poll_wait(NULL, &chan->wq, pt);

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

 	if (chan->in_len)
 		ret |= POLLIN;

 	return ret;
 }

 static void p9_virtio_close(struct p9_trans *trans)
 {
 	struct virtio_chan *chan = trans->priv;

 	down(&virtio_9p_lock);
 	chan->inuse = false;
 	up(&virtio_9p_lock);

 	kfree(trans);
 }

 static bool p9_virtio_intr(struct virtqueue *q)
 {
 	struct virtio_chan *chan = q->vdev->priv;

 	P9_DPRINTK(P9_DEBUG_TRANS, "9p poll_wakeup: %p\n", &chan->wq);
 	wake_up_interruptible(&chan->wq);

 	return true;
 }

 static int p9_virtio_probe(struct virtio_device *dev)
 {
 	int err;
 	struct virtio_chan *chan;
 	int index;

 	down(&virtio_9p_lock);
 	index = chan_index++;
 	chan = &channels[index];
 	up(&virtio_9p_lock);

 	if (chan_index > MAX_9P_CHAN) {
 		printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
 		BUG();
 	}

 	chan->vdev = dev;

 	/* This is the scratch page we use to receive console input */
 	chan->inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!chan->inbuf) {
 		err = -ENOMEM;
 		goto fail;
 	}

 	/* Find the input queue. */
 	dev->priv = chan;
 	chan->in_vq = dev->config->find_vq(dev, p9_virtio_intr);
 	if (IS_ERR(chan->in_vq)) {
 		err = PTR_ERR(chan->in_vq);
 		goto free;
 	}

 	chan->out_vq = dev->config->find_vq(dev, NULL);
 	if (IS_ERR(chan->out_vq)) {
 		err = PTR_ERR(chan->out_vq);
 		goto free_in_vq;
 	}

 	init_waitqueue_head(&chan->wq);

 	/* Register the input buffer the first time. */
 	add_inbuf(chan);
 	chan->inuse = false;
 	chan->initialized = true;

 	return 0;

 free_in_vq:
 	dev->config->del_vq(chan->in_vq);
 free:
 	kfree(chan->inbuf);
 fail:
 	down(&virtio_9p_lock);
 	chan_index--;
 	up(&virtio_9p_lock);
 	return err;
 }

 /* This sets up a transport channel for 9p communication.  Right now
  * we only match the first available channel, but eventually we couldlook up
  * alternate channels by matching devname versus a virtio_config entry.
  * We use a simple reference count mechanism to ensure that only a single
  * mount has a channel open at a time. */
 static struct p9_trans *p9_virtio_create(const char *devname, char *args)
 {
 	struct p9_trans *trans;
 	int index = 0;
 	struct virtio_chan *chan = channels;

 	down(&virtio_9p_lock);
 	while (index < MAX_9P_CHAN) {
 		if (chan->initialized && !chan->inuse) {
 			chan->inuse = true;
 			break;
 		} else {
 			index++;
 			chan = &channels[index];
 		}
 	}
 	up(&virtio_9p_lock);

 	if (index >= MAX_9P_CHAN) {
 		printk(KERN_ERR "9p: virtio: couldn't find a free channel\n");
 		return NULL;
 	}

 	trans = kmalloc(sizeof(struct p9_trans), GFP_KERNEL);
 	if (!trans) {
 		printk(KERN_ERR "9p: couldn't allocate transport\n");
 		return ERR_PTR(-ENOMEM);
 	}

 	trans->write = p9_virtio_write;
 	trans->read = p9_virtio_read;
 	trans->close = p9_virtio_close;
 	trans->poll = p9_virtio_poll;
 	trans->priv = chan;

 	return trans;
 }

 #define VIRTIO_ID_9P 9

 static struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
 	{ 0 },
 };

 /* The standard "struct lguest_driver": */
 static struct virtio_driver p9_virtio_drv = {
 	.driver.name = 	KBUILD_MODNAME,
 	.driver.owner = THIS_MODULE,
 	.id_table =	id_table,
 	.probe = 	p9_virtio_probe,
 };

 static struct p9_trans_module p9_virtio_trans = {
 	.name = "virtio",
 	.create = p9_virtio_create,
 	.maxsize = PAGE_SIZE,
 	.def = 0,
 };

 /* The standard init function */
 static int __init p9_virtio_init(void)
 {
 	int count;

 	for (count = 0; count < MAX_9P_CHAN; count++)
 		channels[count].initialized = false;

 	v9fs_register_trans(&p9_virtio_trans);
 	return register_virtio_driver(&p9_virtio_drv);
 }

 module_init(p9_virtio_init);

 MODULE_DEVICE_TABLE(virtio, id_table);
 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
 MODULE_DESCRIPTION("Virtio 9p Transport");
 MODULE_LICENSE("GPL");
	/*
	* The Guest 9p transport driver
	*
	* This is a trivial pipe-based transport driver based on the lguest console
	* code: we use lguest's DMA mechanism to send bytes out, and register a
	* DMA buffer to receive bytes in. It is assumed to be present and available
	* from the very beginning of boot.
	*
	* This may be have been done by just instaniating another HVC console,
	* but HVC's blocksize of 16 bytes is annoying and painful to performance.
	*
	* A more efficient transport could be built based on the virtio block driver
	* but it requires some changes in the 9p transport model (which are in
	* progress)
	*
	*/
	/*
	* Copyright (C) 2007 Eric Van Hensbergen, IBM Corporation
	*
	* Based on virtio console driver
	* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2
	* as published by the Free Software Foundation.
	*
	* 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:
	* Free Software Foundation
	* 51 Franklin Street, Fifth Floor
	* Boston, MA 02111-1301 USA
	*
	*/

	#include <linux/in.h>
	#include <linux/module.h>
	#include <linux/net.h>
	#include <linux/ipv6.h>
	#include <linux/errno.h>
	#include <linux/kernel.h>
	#include <linux/un.h>
	#include <linux/uaccess.h>
	#include <linux/inet.h>
	#include <linux/idr.h>
	#include <linux/file.h>
	#include <net/9p/9p.h>
	#include <linux/parser.h>
	#include <net/9p/transport.h>
	#include <linux/scatterlist.h>
	#include <linux/virtio.h>
	#include <linux/virtio_9p.h>

	/* a single mutex to manage channel initialization and attachment */
	static DECLARE_MUTEX(virtio_9p_lock);
	/* global which tracks highest initialized channel */
	static int chan_index;

	/* We keep all per-channel information in a structure.
	* This structure is allocated within the devices dev->mem space.
	* A pointer to the structure will get put in the transport private.
	*/
	static struct virtio_chan {
	bool initialized; /* channel is initialized */
	bool inuse; /* channel is in use */

	struct virtqueue in_vq, out_vq;
	struct virtio_device *vdev;

	/* This is our input buffer, and how much data is left in it. */
	unsigned int in_len;
	char in, inbuf;

	wait_queue_head_t wq; /* waitq for buffer */
	} channels[MAX_9P_CHAN];

	/* How many bytes left in this page. */
	static unsigned int rest_of_page(void *data)
	{
	return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
	}

	static int p9_virtio_write(struct p9_trans trans, void buf, int count)
	{
	struct virtio_chan chan = (struct virtio_chan ) trans->priv;
	struct virtqueue *out_vq = chan->out_vq;
	struct scatterlist sg[1];
	unsigned int len;

	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio write (%d)\n", count);

	/* keep it simple - make sure we don't overflow a page */
	if (rest_of_page(buf) < count)
	count = rest_of_page(buf);

	sg_init_one(sg, buf, count);

	/* add_buf wants a token to identify this buffer: we hand it any
	* non-NULL pointer, since there's only ever one buffer. */
	if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) == 0) {
	/* Tell Host to go! */
	out_vq->vq_ops->kick(out_vq);
	/* Chill out until it's done with the buffer. */
	while (!out_vq->vq_ops->get_buf(out_vq, &len))
	cpu_relax();
	}

	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio wrote (%d)\n", count);

	/* We're expected to return the amount of data we wrote: all of it. */
	return count;
	}

	/* Create a scatter-gather list representing our input buffer and put it in the
	* queue. */
	static void add_inbuf(struct virtio_chan *chan)
	{
	struct scatterlist sg[1];

	sg_init_one(sg, chan->inbuf, PAGE_SIZE);

	/* We should always be able to add one buffer to an empty queue. */
	if (chan->in_vq->vq_ops->add_buf(chan->in_vq, sg, 0, 1, chan->inbuf))
	BUG();
	chan->in_vq->vq_ops->kick(chan->in_vq);
	}

	static int p9_virtio_read(struct p9_trans trans, void buf, int count)
	{
	struct virtio_chan chan = (struct virtio_chan ) trans->priv;
	struct virtqueue *in_vq = chan->in_vq;

	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio read (%d)\n", count);

	/* If we don't have an input queue yet, we can't get input. */
	BUG_ON(!in_vq);

	/* No buffer? Try to get one. */
	if (!chan->in_len) {
	chan->in = in_vq->vq_ops->get_buf(in_vq, &chan->in_len);
	if (!chan->in)
	return 0;
	}

	/* You want more than we have to give? Well, try wanting less! */
	if (chan->in_len < count)
	count = chan->in_len;

	/* Copy across to their buffer and increment offset. */
	memcpy(buf, chan->in, count);
	chan->in += count;
	chan->in_len -= count;

	/* Finished? Re-register buffer so Host will use it again. */
	if (chan->in_len == 0)
	add_inbuf(chan);

	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio finished read (%d)\n",
	count);

	return count;
	}

	/* The poll function is used by 9p transports to determine if there
	* is there is activity available on a particular channel. In our case
	* we use it to wait for a callback from the input routines.
	*/
	static unsigned int
	p9_virtio_poll(struct p9_trans trans, struct poll_table_struct pt)
	{
	struct virtio_chan chan = (struct virtio_chan )trans->priv;
	struct virtqueue *in_vq = chan->in_vq;
	int ret = POLLOUT; /* we can always handle more output */

	poll_wait(NULL, &chan->wq, pt);

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

	if (chan->in_len)
	ret \|= POLLIN;

	return ret;
	}

	static void p9_virtio_close(struct p9_trans *trans)
	{
	struct virtio_chan *chan = trans->priv;

	down(&virtio_9p_lock);
	chan->inuse = false;
	up(&virtio_9p_lock);

	kfree(trans);
	}

	static bool p9_virtio_intr(struct virtqueue *q)
	{
	struct virtio_chan *chan = q->vdev->priv;

	P9_DPRINTK(P9_DEBUG_TRANS, "9p poll_wakeup: %p\n", &chan->wq);
	wake_up_interruptible(&chan->wq);

	return true;
	}

	static int p9_virtio_probe(struct virtio_device *dev)
	{
	int err;
	struct virtio_chan *chan;
	int index;

	down(&virtio_9p_lock);
	index = chan_index++;
	chan = &channels[index];
	up(&virtio_9p_lock);

	if (chan_index > MAX_9P_CHAN) {
	printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
	BUG();
	}

	chan->vdev = dev;

	/* This is the scratch page we use to receive console input */
	chan->inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!chan->inbuf) {
	err = -ENOMEM;
	goto fail;
	}

	/* Find the input queue. */
	dev->priv = chan;
	chan->in_vq = dev->config->find_vq(dev, p9_virtio_intr);
	if (IS_ERR(chan->in_vq)) {
	err = PTR_ERR(chan->in_vq);
	goto free;
	}

	chan->out_vq = dev->config->find_vq(dev, NULL);
	if (IS_ERR(chan->out_vq)) {
	err = PTR_ERR(chan->out_vq);
	goto free_in_vq;
	}

	init_waitqueue_head(&chan->wq);

	/* Register the input buffer the first time. */
	add_inbuf(chan);
	chan->inuse = false;
	chan->initialized = true;

	return 0;

	free_in_vq:
	dev->config->del_vq(chan->in_vq);
	free:
	kfree(chan->inbuf);
	fail:
	down(&virtio_9p_lock);
	chan_index--;
	up(&virtio_9p_lock);
	return err;
	}

	/* This sets up a transport channel for 9p communication. Right now
	* we only match the first available channel, but eventually we couldlook up
	* alternate channels by matching devname versus a virtio_config entry.
	* We use a simple reference count mechanism to ensure that only a single
	* mount has a channel open at a time. */
	static struct p9_trans p9_virtio_create(const char devname, char *args)
	{
	struct p9_trans *trans;
	int index = 0;
	struct virtio_chan *chan = channels;

	down(&virtio_9p_lock);
	while (index < MAX_9P_CHAN) {
	if (chan->initialized && !chan->inuse) {
	chan->inuse = true;
	break;
	} else {
	index++;
	chan = &channels[index];
	}
	}
	up(&virtio_9p_lock);

	if (index >= MAX_9P_CHAN) {
	printk(KERN_ERR "9p: virtio: couldn't find a free channel\n");
	return NULL;
	}

	trans = kmalloc(sizeof(struct p9_trans), GFP_KERNEL);
	if (!trans) {
	printk(KERN_ERR "9p: couldn't allocate transport\n");
	return ERR_PTR(-ENOMEM);
	}

	trans->write = p9_virtio_write;
	trans->read = p9_virtio_read;
	trans->close = p9_virtio_close;
	trans->poll = p9_virtio_poll;
	trans->priv = chan;

	return trans;
	}

	#define VIRTIO_ID_9P 9

	static struct virtio_device_id id_table[] = {
	{ VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
	{ 0 },
	};

	/* The standard "struct lguest_driver": */
	static struct virtio_driver p9_virtio_drv = {
	.driver.name = KBUILD_MODNAME,
	.driver.owner = THIS_MODULE,
	.id_table = id_table,
	.probe = p9_virtio_probe,
	};

	static struct p9_trans_module p9_virtio_trans = {
	.name = "virtio",
	.create = p9_virtio_create,
	.maxsize = PAGE_SIZE,
	.def = 0,
	};

	/* The standard init function */
	static int __init p9_virtio_init(void)
	{
	int count;

	for (count = 0; count < MAX_9P_CHAN; count++)
	channels[count].initialized = false;

	v9fs_register_trans(&p9_virtio_trans);
	return register_virtio_driver(&p9_virtio_drv);
	}

	module_init(p9_virtio_init);

	MODULE_DEVICE_TABLE(virtio, id_table);
	MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
	MODULE_DESCRIPTION("Virtio 9p Transport");
	MODULE_LICENSE("GPL");