aboutsummaryrefslogtreecommitdiffstats
path: root/net/9p/trans_virtio.c
blob: 961e025957ae99783e1c95068a5fcde812b6e941 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
/*
 * 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 <linux/slab.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>
#include "trans_common.h"

#define VIRTQUEUE_NUM	128

/* a single mutex to manage channel initialization and attachment */
static DEFINE_MUTEX(virtio_9p_lock);

/**
 * 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.
 *
 */

struct virtio_chan {
	bool inuse;

	spinlock_t lock;

	struct p9_client *client;
	struct virtio_device *vdev;
	struct virtqueue *vq;
	int ring_bufs_avail;
	wait_queue_head_t *vc_wq;

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

	int tag_len;
	/*
	 * tag name to identify a mount Non-null terminated
	 */
	char *tag;

	struct list_head chan_list;
};

static struct list_head virtio_chan_list;

/* 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);
	if (chan)
		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;
	unsigned long flags;

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

	do {
		spin_lock_irqsave(&chan->lock, flags);
		rc = virtqueue_get_buf(chan->vq, &len);

		if (rc != NULL) {
			chan->ring_bufs_avail = 1;
			spin_unlock_irqrestore(&chan->lock, flags);
			/* Wakeup if anyone waiting for VirtIO ring space. */
			wake_up(chan->vc_wq);
			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;
			if (req->tc->private) {
				struct trans_rpage_info *rp = req->tc->private;
				/*Release pages */
				p9_release_req_pages(rp);
				if (rp->rp_alloc)
					kfree(rp);
				req->tc->private = NULL;
			}
			p9_client_cb(chan->client, req);
		} else {
			spin_unlock_irqrestore(&chan->lock, flags);
		}
	} while (rc != NULL);
}

/**
 * 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;
}

/**
 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
 * this takes a list of pages.
 * @sg: scatter/gather list to pack into
 * @start: which segment of the sg_list to start at
 * @pdata_off: Offset into the first page
 * @**pdata: a list of pages to add into sg.
 * @count: amount of data to pack into the scatter/gather list
 */
static int
pack_sg_list_p(struct scatterlist *sg, int start, int limit, size_t pdata_off,
		struct page **pdata, int count)
{
	int s;
	int i = 0;
	int index = start;

	if (pdata_off) {
		s = min((int)(PAGE_SIZE - pdata_off), count);
		sg_set_page(&sg[index++], pdata[i++], s, pdata_off);
		count -= s;
	}

	while (count) {
		BUG_ON(index > limit);
		s = min((int)PAGE_SIZE, count);
		sg_set_page(&sg[index++], pdata[i++], s, 0);
		count -= s;
	}
	return index-start;
}

/**
 * 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, inp, outp;
	struct virtio_chan *chan = client->trans;
	char *rdata = (char *)req->rc+sizeof(struct p9_fcall);
	unsigned long flags;
	size_t pdata_off = 0;
	struct trans_rpage_info *rpinfo = NULL;
	int err, pdata_len = 0;

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

req_retry:
	req->status = REQ_STATUS_SENT;

	if (req->tc->pbuf_size && (req->tc->pubuf && P9_IS_USER_CONTEXT)) {
		int nr_pages = p9_nr_pages(req);
		int rpinfo_size = sizeof(struct trans_rpage_info) +
			sizeof(struct page *) * nr_pages;

		if (rpinfo_size <= (req->tc->capacity - req->tc->size)) {
			/* We can use sdata */
			req->tc->private = req->tc->sdata + req->tc->size;
			rpinfo = (struct trans_rpage_info *)req->tc->private;
			rpinfo->rp_alloc = 0;
		} else {
			req->tc->private = kmalloc(rpinfo_size, GFP_NOFS);
			if (!req->tc->private) {
				P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: "
					"private kmalloc returned NULL");
				return -ENOMEM;
			}
			rpinfo = (struct trans_rpage_info *)req->tc->private;
			rpinfo->rp_alloc = 1;
		}

		err = p9_payload_gup(req, &pdata_off, &pdata_len, nr_pages,
				req->tc->id == P9_TREAD ? 1 : 0);
		if (err < 0) {
			if (rpinfo->rp_alloc)
				kfree(rpinfo);
			return err;
		}
	}

	spin_lock_irqsave(&chan->lock, flags);

	/* Handle out VirtIO ring buffers */
	out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata,
			req->tc->size);

	if (req->tc->pbuf_size && (req->tc->id == P9_TWRITE)) {
		/* We have additional write payload buffer to take care */
		if (req->tc->pubuf && P9_IS_USER_CONTEXT) {
			outp = pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
					pdata_off, rpinfo->rp_data, pdata_len);
		} else {
			char *pbuf = req->tc->pubuf ? req->tc->pubuf :
								req->tc->pkbuf;
			outp = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, pbuf,
					req->tc->pbuf_size);
		}
		out += outp;
	}

	/* Handle in VirtIO ring buffers */
	if (req->tc->pbuf_size &&
		((req->tc->id == P9_TREAD) || (req->tc->id == P9_TREADDIR))) {
		/*
		 * Take care of additional Read payload.
		 * 11 is the read/write header = PDU Header(7) + IO Size (4).
		 * Arrange in such a way that server places header in the
		 * alloced memory and payload onto the user buffer.
		 */
		inp = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, rdata, 11);
		/*
		 * Running executables in the filesystem may result in
		 * a read request with kernel buffer as opposed to user buffer.
		 */
		if (req->tc->pubuf && P9_IS_USER_CONTEXT) {
			in = pack_sg_list_p(chan->sg, out+inp, VIRTQUEUE_NUM,
					pdata_off, rpinfo->rp_data, pdata_len);
		} else {
			char *pbuf = req->tc->pubuf ? req->tc->pubuf :
								req->tc->pkbuf;
			in = pack_sg_list(chan->sg, out+inp, VIRTQUEUE_NUM,
					pbuf, req->tc->pbuf_size);
		}
		in += inp;
	} else {
		in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, rdata,
				client->msize);
	}

	err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc);
	if (err < 0) {
		if (err == -ENOSPC) {
			chan->ring_bufs_avail = 0;
			spin_unlock_irqrestore(&chan->lock, flags);
			err = wait_event_interruptible(*chan->vc_wq,
							chan->ring_bufs_avail);
			if (err  == -ERESTARTSYS)
				return err;

			P9_DPRINTK(P9_DEBUG_TRANS, "9p:Retry virtio request\n");
			goto req_retry;
		} else {
			spin_unlock_irqrestore(&chan->lock, flags);
			P9_DPRINTK(P9_DEBUG_TRANS,
					"9p debug: "
					"virtio rpc add_buf returned failure");
			if (rpinfo && rpinfo->rp_alloc)
				kfree(rpinfo);
			return -EIO;
		}
	}

	virtqueue_kick(chan->vq);
	spin_unlock_irqrestore(&chan->lock, flags);

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

static ssize_t p9_mount_tag_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	struct virtio_chan *chan;
	struct virtio_device *vdev;

	vdev = dev_to_virtio(dev);
	chan = vdev->priv;

	return snprintf(buf, chan->tag_len + 1, "%s", chan->tag);
}

static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);

/**
 * p9_virtio_probe - probe for existence of 9P virtio channels
 * @vdev: virtio device to probe
 *
 * This probes for existing virtio channels.
 *
 */

static int p9_virtio_probe(struct virtio_device *vdev)
{
	__u16 tag_len;
	char *tag;
	int err;
	struct virtio_chan *chan;

	chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
	if (!chan) {
		printk(KERN_ERR "9p: Failed to allocate virtio 9P channel\n");
		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;
	if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) {
		vdev->config->get(vdev,
				offsetof(struct virtio_9p_config, tag_len),
				&tag_len, sizeof(tag_len));
	} else {
		err = -EINVAL;
		goto out_free_vq;
	}
	tag = kmalloc(tag_len, GFP_KERNEL);
	if (!tag) {
		err = -ENOMEM;
		goto out_free_vq;
	}
	vdev->config->get(vdev, offsetof(struct virtio_9p_config, tag),
			tag, tag_len);
	chan->tag = tag;
	chan->tag_len = tag_len;
	err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
	if (err) {
		goto out_free_tag;
	}
	chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
	if (!chan->vc_wq) {
		err = -ENOMEM;
		goto out_free_tag;
	}
	init_waitqueue_head(chan->vc_wq);
	chan->ring_bufs_avail = 1;

	mutex_lock(&virtio_9p_lock);
	list_add_tail(&chan->chan_list, &virtio_chan_list);
	mutex_unlock(&virtio_9p_lock);
	return 0;

out_free_tag:
	kfree(tag);
out_free_vq:
	vdev->config->del_vqs(vdev);
	kfree(chan);
fail:
	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.
 *
 */

static int
p9_virtio_create(struct p9_client *client, const char *devname, char *args)
{
	struct virtio_chan *chan;
	int ret = -ENOENT;
	int found = 0;

	mutex_lock(&virtio_9p_lock);
	list_for_each_entry(chan, &virtio_chan_list, chan_list) {
		if (!strncmp(devname, chan->tag, chan->tag_len) &&
		    strlen(devname) == chan->tag_len) {
			if (!chan->inuse) {
				chan->inuse = true;
				found = 1;
				break;
			}
			ret = -EBUSY;
		}
	}
	mutex_unlock(&virtio_9p_lock);

	if (!found) {
		printk(KERN_ERR "9p: no channels available\n");
		return ret;
	}

	client->trans = (void *)chan;
	client->status = Connected;
	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);
	vdev->config->del_vqs(vdev);

	mutex_lock(&virtio_9p_lock);
	list_del(&chan->chan_list);
	mutex_unlock(&virtio_9p_lock);
	sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
	kfree(chan->tag);
	kfree(chan->vc_wq);
	kfree(chan);

}

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

static unsigned int features[] = {
	VIRTIO_9P_MOUNT_TAG,
};

/* The standard "struct lguest_driver": */
static struct virtio_driver p9_virtio_drv = {
	.feature_table  = features,
	.feature_table_size = ARRAY_SIZE(features),
	.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,
	.pref = P9_TRANS_PREF_PAYLOAD_SEP,
	.def = 0,
	.owner = THIS_MODULE,
};

/* The standard init function */
static int __init p9_virtio_init(void)
{
	INIT_LIST_HEAD(&virtio_chan_list);

	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");