[deliverable/linux.git] / net / 9p / trans_virtio.c

/*
 * The Virtio 9p transport driver
 *
 * This is a block based transport driver based on the lguest block driver
 * code.
 *
 *  Copyright (C) 2007, 2008 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/client.h>
#include <net/9p/transport.h>
#include <linux/scatterlist.h>
#include <linux/virtio.h>
#include <linux/virtio_9p.h>

#define VIRTQUEUE_NUM	128

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

/**
 * struct virtio_chan - per-instance transport information
 * @initialized: whether the channel is initialized
 * @inuse: whether the channel is in use
 * @lock: protects multiple elements within this structure
 * @client: client instance
 * @vdev: virtio dev associated with this channel
 * @vq: virtio queue associated with this channel
 * @sg: scatter gather list which is used to pack a request (protected?)
 *
 * 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;
	bool inuse;

	spinlock_t lock;

	struct p9_client *client;
	struct virtio_device *vdev;
	struct virtqueue *vq;

	/* Scatterlist: can be too big for stack. */
	struct scatterlist sg[VIRTQUEUE_NUM];
} 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);
}

/**
 * p9_virtio_close - reclaim resources of a channel
 * @client: client instance
 *
 * This reclaims a channel by freeing its resources and
 * reseting its inuse flag.
 *
 */

static void p9_virtio_close(struct p9_client *client)
{
	struct virtio_chan *chan = client->trans;

	mutex_lock(&virtio_9p_lock);
	chan->inuse = false;
	mutex_unlock(&virtio_9p_lock);
}

/**
 * req_done - callback which signals activity from the server
 * @vq: virtio queue activity was received on
 *
 * This notifies us that the server has triggered some activity
 * on the virtio channel - most likely a response to request we
 * sent.  Figure out which requests now have responses and wake up
 * those threads.
 *
 * Bugs: could do with some additional sanity checking, but appears to work.
 *
 */

static void req_done(struct virtqueue *vq)
{
	struct virtio_chan *chan = vq->vdev->priv;
	struct p9_fcall *rc;
	unsigned int len;
	struct p9_req_t *req;

	P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");

	while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) {
		P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc);
		P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
		req = p9_tag_lookup(chan->client, rc->tag);
		req->status = REQ_STATUS_RCVD;
		p9_client_cb(chan->client, req);
	}
}

/**
 * pack_sg_list - pack a scatter gather list from a linear buffer
 * @sg: scatter/gather list to pack into
 * @start: which segment of the sg_list to start at
 * @limit: maximum segment to pack data to
 * @data: data to pack into scatter/gather list
 * @count: amount of data to pack into the scatter/gather list
 *
 * sg_lists have multiple segments of various sizes.  This will pack
 * arbitrary data into an existing scatter gather list, segmenting the
 * data as necessary within constraints.
 *
 */

static int
pack_sg_list(struct scatterlist *sg, int start, int limit, char *data,
								int count)
{
	int s;
	int index = start;

	while (count) {
		s = rest_of_page(data);
		if (s > count)
			s = count;
		sg_set_buf(&sg[index++], data, s);
		count -= s;
		data += s;
		BUG_ON(index > limit);
	}

	return index-start;
}

/* We don't currently allow canceling of virtio requests */
static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
{
	return 1;
}

/**
 * p9_virtio_request - issue a request
 * @client: client instance issuing the request
 * @req: request to be issued
 *
 */

static int
p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
{
	int in, out;
	struct virtio_chan *chan = client->trans;
	char *rdata = (char *)req->rc+sizeof(struct p9_fcall);

	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");

	out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata,
								req->tc->size);
	in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata,
								client->msize);

	req->status = REQ_STATUS_SENT;

	if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, req->tc)) {
		P9_DPRINTK(P9_DEBUG_TRANS,
			"9p debug: virtio rpc add_buf returned failure");
		return -EIO;
	}

	chan->vq->vq_ops->kick(chan->vq);

	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n");
	return 0;
}

/**
 * p9_virtio_probe - probe for existence of 9P virtio channels
 * @vdev: virtio device to probe
 *
 * This probes for existing virtio channels.  At present only
 * a single channel is in use, so in the future more work may need
 * to be done here.
 *
 */

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

	mutex_lock(&virtio_9p_lock);
	index = chan_index++;
	chan = &channels[index];
	mutex_unlock(&virtio_9p_lock);

	if (chan_index > MAX_9P_CHAN) {
		printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
		BUG();
		err = -ENOMEM;
		goto fail;
	}

	chan->vdev = vdev;

	/* We expect one virtqueue, for requests. */
	chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
	if (IS_ERR(chan->vq)) {
		err = PTR_ERR(chan->vq);
		goto out_free_vq;
	}
	chan->vq->vdev->priv = chan;
	spin_lock_init(&chan->lock);

	sg_init_table(chan->sg, VIRTQUEUE_NUM);

	chan->inuse = false;
	chan->initialized = true;
	return 0;

out_free_vq:
	vdev->config->del_vqs(vdev);
fail:
	mutex_lock(&virtio_9p_lock);
	chan_index--;
	mutex_unlock(&virtio_9p_lock);
	return err;
}


/**
 * p9_virtio_create - allocate a new virtio channel
 * @client: client instance invoking this transport
 * @devname: string identifying the channel to connect to (unused)
 * @args: args passed from sys_mount() for per-transport options (unused)
 *
 * 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.
 *
 * Bugs: doesn't allow identification of a specific channel
 * to allocate, channels are allocated sequentially. This was
 * a pragmatic decision to get things rolling, but ideally some
 * way of identifying the channel to attach to would be nice
 * if we are going to support multiple channels.
 *
 */

static int
p9_virtio_create(struct p9_client *client, const char *devname, char *args)
{
	struct virtio_chan *chan = channels;
	int index = 0;

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

	if (index >= MAX_9P_CHAN) {
		printk(KERN_ERR "9p: no channels available\n");
		return -ENODEV;
	}

	client->trans = (void *)chan;
	chan->client = client;

	return 0;
}

/**
 * p9_virtio_remove - clean up resources associated with a virtio device
 * @vdev: virtio device to remove
 *
 */

static void p9_virtio_remove(struct virtio_device *vdev)
{
	struct virtio_chan *chan = vdev->priv;

	BUG_ON(chan->inuse);

	if (chan->initialized) {
		vdev->config->del_vqs(vdev);
		chan->initialized = false;
	}
}

#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,
	.remove =	p9_virtio_remove,
};

static struct p9_trans_module p9_virtio_trans = {
	.name = "virtio",
	.create = p9_virtio_create,
	.close = p9_virtio_close,
	.request = p9_virtio_request,
	.cancel = p9_virtio_cancel,
	.maxsize = PAGE_SIZE*16,
	.def = 0,
	.owner = THIS_MODULE,
};

/* 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);
}

static void __exit p9_virtio_cleanup(void)
{
	unregister_virtio_driver(&p9_virtio_drv);
	v9fs_unregister_trans(&p9_virtio_trans);
}

module_init(p9_virtio_init);
module_exit(p9_virtio_cleanup);

MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
MODULE_DESCRIPTION("Virtio 9p Transport");
MODULE_LICENSE("GPL");
Commit	Line	Data
	1	/*
	2	* The Virtio 9p transport driver
	3	*
	4	* This is a block based transport driver based on the lguest block driver
	5	* code.
	6	*
	7	* Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
	8	*
	9	* Based on virtio console driver
	10	* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
	11	*
	12	* This program is free software; you can redistribute it and/or modify
	13	* it under the terms of the GNU General Public License version 2
	14	* as published by the Free Software Foundation.
	15	*
	16	* This program is distributed in the hope that it will be useful,
	17	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	18	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	19	* GNU General Public License for more details.
	20	*
	21	* You should have received a copy of the GNU General Public License
	22	* along with this program; if not, write to:
	23	* Free Software Foundation
	24	* 51 Franklin Street, Fifth Floor
	25	* Boston, MA 02111-1301 USA
	26	*
	27	*/
	28
	29	#include <linux/in.h>
	30	#include <linux/module.h>
	31	#include <linux/net.h>
	32	#include <linux/ipv6.h>
	33	#include <linux/errno.h>
	34	#include <linux/kernel.h>
	35	#include <linux/un.h>
	36	#include <linux/uaccess.h>
	37	#include <linux/inet.h>
	38	#include <linux/idr.h>
	39	#include <linux/file.h>
	40	#include <net/9p/9p.h>
	41	#include <linux/parser.h>
	42	#include <net/9p/client.h>
	43	#include <net/9p/transport.h>
	44	#include <linux/scatterlist.h>
	45	#include <linux/virtio.h>
	46	#include <linux/virtio_9p.h>
	47
	48	#define VIRTQUEUE_NUM 128
	49
	50	/* a single mutex to manage channel initialization and attachment */
	51	static DEFINE_MUTEX(virtio_9p_lock);
	52	/* global which tracks highest initialized channel */
	53	static int chan_index;
	54
	55	/**
	56	* struct virtio_chan - per-instance transport information
	57	* @initialized: whether the channel is initialized
	58	* @inuse: whether the channel is in use
	59	* @lock: protects multiple elements within this structure
	60	* @client: client instance
	61	* @vdev: virtio dev associated with this channel
	62	* @vq: virtio queue associated with this channel
	63	* @sg: scatter gather list which is used to pack a request (protected?)
	64	*
	65	* We keep all per-channel information in a structure.
	66	* This structure is allocated within the devices dev->mem space.
	67	* A pointer to the structure will get put in the transport private.
	68	*
	69	*/
	70
	71	static struct virtio_chan {
	72	bool initialized;
	73	bool inuse;
	74
	75	spinlock_t lock;
	76
	77	struct p9_client *client;
	78	struct virtio_device *vdev;
	79	struct virtqueue *vq;
	80
	81	/* Scatterlist: can be too big for stack. */
	82	struct scatterlist sg[VIRTQUEUE_NUM];
	83	} channels[MAX_9P_CHAN];
	84
	85	/* How many bytes left in this page. */
	86	static unsigned int rest_of_page(void *data)
	87	{
	88	return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
	89	}
	90
	91	/**
	92	* p9_virtio_close - reclaim resources of a channel
	93	* @client: client instance
	94	*
	95	* This reclaims a channel by freeing its resources and
	96	* reseting its inuse flag.
	97	*
	98	*/
	99
	100	static void p9_virtio_close(struct p9_client *client)
	101	{
	102	struct virtio_chan *chan = client->trans;
	103
	104	mutex_lock(&virtio_9p_lock);
	105	chan->inuse = false;
	106	mutex_unlock(&virtio_9p_lock);
	107	}
	108
	109	/**
	110	* req_done - callback which signals activity from the server
	111	* @vq: virtio queue activity was received on
	112	*
	113	* This notifies us that the server has triggered some activity
	114	* on the virtio channel - most likely a response to request we
	115	* sent. Figure out which requests now have responses and wake up
	116	* those threads.
	117	*
	118	* Bugs: could do with some additional sanity checking, but appears to work.
	119	*
	120	*/
	121
	122	static void req_done(struct virtqueue *vq)
	123	{
	124	struct virtio_chan *chan = vq->vdev->priv;
	125	struct p9_fcall *rc;
	126	unsigned int len;
	127	struct p9_req_t *req;
	128
	129	P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");
	130
	131	while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) {
	132	P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc);
	133	P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
	134	req = p9_tag_lookup(chan->client, rc->tag);
	135	req->status = REQ_STATUS_RCVD;
	136	p9_client_cb(chan->client, req);
	137	}
	138	}
	139
	140	/**
	141	* pack_sg_list - pack a scatter gather list from a linear buffer
	142	* @sg: scatter/gather list to pack into
	143	* @start: which segment of the sg_list to start at
	144	* @limit: maximum segment to pack data to
	145	* @data: data to pack into scatter/gather list
	146	* @count: amount of data to pack into the scatter/gather list
	147	*
	148	* sg_lists have multiple segments of various sizes. This will pack
	149	* arbitrary data into an existing scatter gather list, segmenting the
	150	* data as necessary within constraints.
	151	*
	152	*/
	153
	154	static int
	155	pack_sg_list(struct scatterlist sg, int start, int limit, char data,
	156	int count)
	157	{
	158	int s;
	159	int index = start;
	160
	161	while (count) {
	162	s = rest_of_page(data);
	163	if (s > count)
	164	s = count;
	165	sg_set_buf(&sg[index++], data, s);
	166	count -= s;
	167	data += s;
	168	BUG_ON(index > limit);
	169	}
	170
	171	return index-start;
	172	}
	173
	174	/* We don't currently allow canceling of virtio requests */
	175	static int p9_virtio_cancel(struct p9_client client, struct p9_req_t req)
	176	{
	177	return 1;
	178	}
	179
	180	/**
	181	* p9_virtio_request - issue a request
	182	* @client: client instance issuing the request
	183	* @req: request to be issued
	184	*
	185	*/
	186
	187	static int
	188	p9_virtio_request(struct p9_client client, struct p9_req_t req)
	189	{
	190	int in, out;
	191	struct virtio_chan *chan = client->trans;
	192	char rdata = (char )req->rc+sizeof(struct p9_fcall);
	193
	194	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");
	195
	196	out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata,
	197	req->tc->size);
	198	in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata,
	199	client->msize);
	200
	201	req->status = REQ_STATUS_SENT;
	202
	203	if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, req->tc)) {
	204	P9_DPRINTK(P9_DEBUG_TRANS,
	205	"9p debug: virtio rpc add_buf returned failure");
	206	return -EIO;
	207	}
	208
	209	chan->vq->vq_ops->kick(chan->vq);
	210
	211	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n");
	212	return 0;
	213	}
	214
	215	/**
	216	* p9_virtio_probe - probe for existence of 9P virtio channels
	217	* @vdev: virtio device to probe
	218	*
	219	* This probes for existing virtio channels. At present only
	220	* a single channel is in use, so in the future more work may need
	221	* to be done here.
	222	*
	223	*/
	224
	225	static int p9_virtio_probe(struct virtio_device *vdev)
	226	{
	227	int err;
	228	struct virtio_chan *chan;
	229	int index;
	230
	231	mutex_lock(&virtio_9p_lock);
	232	index = chan_index++;
	233	chan = &channels[index];
	234	mutex_unlock(&virtio_9p_lock);
	235
	236	if (chan_index > MAX_9P_CHAN) {
	237	printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
	238	BUG();
	239	err = -ENOMEM;
	240	goto fail;
	241	}
	242
	243	chan->vdev = vdev;
	244
	245	/* We expect one virtqueue, for requests. */
	246	chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
	247	if (IS_ERR(chan->vq)) {
	248	err = PTR_ERR(chan->vq);
	249	goto out_free_vq;
	250	}
	251	chan->vq->vdev->priv = chan;
	252	spin_lock_init(&chan->lock);
	253
	254	sg_init_table(chan->sg, VIRTQUEUE_NUM);
	255
	256	chan->inuse = false;
	257	chan->initialized = true;
	258	return 0;
	259
	260	out_free_vq:
	261	vdev->config->del_vqs(vdev);
	262	fail:
	263	mutex_lock(&virtio_9p_lock);
	264	chan_index--;
	265	mutex_unlock(&virtio_9p_lock);
	266	return err;
	267	}
	268
	269
	270	/**
	271	* p9_virtio_create - allocate a new virtio channel
	272	* @client: client instance invoking this transport
	273	* @devname: string identifying the channel to connect to (unused)
	274	* @args: args passed from sys_mount() for per-transport options (unused)
	275	*
	276	* This sets up a transport channel for 9p communication. Right now
	277	* we only match the first available channel, but eventually we couldlook up
	278	* alternate channels by matching devname versus a virtio_config entry.
	279	* We use a simple reference count mechanism to ensure that only a single
	280	* mount has a channel open at a time.
	281	*
	282	* Bugs: doesn't allow identification of a specific channel
	283	* to allocate, channels are allocated sequentially. This was
	284	* a pragmatic decision to get things rolling, but ideally some
	285	* way of identifying the channel to attach to would be nice
	286	* if we are going to support multiple channels.
	287	*
	288	*/
	289
	290	static int
	291	p9_virtio_create(struct p9_client client, const char devname, char *args)
	292	{
	293	struct virtio_chan *chan = channels;
	294	int index = 0;
	295
	296	mutex_lock(&virtio_9p_lock);
	297	while (index < MAX_9P_CHAN) {
	298	if (chan->initialized && !chan->inuse) {
	299	chan->inuse = true;
	300	break;
	301	} else {
	302	index++;
	303	chan = &channels[index];
	304	}
	305	}
	306	mutex_unlock(&virtio_9p_lock);
	307
	308	if (index >= MAX_9P_CHAN) {
	309	printk(KERN_ERR "9p: no channels available\n");
	310	return -ENODEV;
	311	}
	312
	313	client->trans = (void *)chan;
	314	chan->client = client;
	315
	316	return 0;
	317	}
	318
	319	/**
	320	* p9_virtio_remove - clean up resources associated with a virtio device
	321	* @vdev: virtio device to remove
	322	*
	323	*/
	324
	325	static void p9_virtio_remove(struct virtio_device *vdev)
	326	{
	327	struct virtio_chan *chan = vdev->priv;
	328
	329	BUG_ON(chan->inuse);
	330
	331	if (chan->initialized) {
	332	vdev->config->del_vqs(vdev);
	333	chan->initialized = false;
	334	}
	335	}
	336
	337	#define VIRTIO_ID_9P 9
	338
	339	static struct virtio_device_id id_table[] = {
	340	{ VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
	341	{ 0 },
	342	};
	343
	344	/* The standard "struct lguest_driver": */
	345	static struct virtio_driver p9_virtio_drv = {
	346	.driver.name = KBUILD_MODNAME,
	347	.driver.owner = THIS_MODULE,
	348	.id_table = id_table,
	349	.probe = p9_virtio_probe,
	350	.remove = p9_virtio_remove,
	351	};
	352
	353	static struct p9_trans_module p9_virtio_trans = {
	354	.name = "virtio",
	355	.create = p9_virtio_create,
	356	.close = p9_virtio_close,
	357	.request = p9_virtio_request,
	358	.cancel = p9_virtio_cancel,
	359	.maxsize = PAGE_SIZE*16,
	360	.def = 0,
	361	.owner = THIS_MODULE,
	362	};
	363
	364	/* The standard init function */
	365	static int __init p9_virtio_init(void)
	366	{
	367	int count;
	368
	369	for (count = 0; count < MAX_9P_CHAN; count++)
	370	channels[count].initialized = false;
	371
	372	v9fs_register_trans(&p9_virtio_trans);
	373	return register_virtio_driver(&p9_virtio_drv);
	374	}
	375
	376	static void __exit p9_virtio_cleanup(void)
	377	{
	378	unregister_virtio_driver(&p9_virtio_drv);
	379	v9fs_unregister_trans(&p9_virtio_trans);
	380	}
	381
	382	module_init(p9_virtio_init);
	383	module_exit(p9_virtio_cleanup);
	384
	385	MODULE_DEVICE_TABLE(virtio, id_table);
	386	MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
	387	MODULE_DESCRIPTION("Virtio 9p Transport");
	388	MODULE_LICENSE("GPL");