1 /*
2 * The Guest 9p transport driver
3 *
4 * This is a block based transport driver based on the lguest block driver
5 * code.
6 *
7 */
8 /*
9 * Copyright (C) 2007 Eric Van Hensbergen, IBM Corporation
10 *
11 * Based on virtio console driver
12 * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
13 *
14 * This program is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License version 2
16 * as published by the Free Software Foundation.
17 *
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
22 *
23 * You should have received a copy of the GNU General Public License
24 * along with this program; if not, write to:
25 * Free Software Foundation
26 * 51 Franklin Street, Fifth Floor
27 * Boston, MA 02111-1301 USA
28 *
29 */
30
31 #include <linux/in.h>
32 #include <linux/module.h>
33 #include <linux/net.h>
34 #include <linux/ipv6.h>
35 #include <linux/errno.h>
36 #include <linux/kernel.h>
37 #include <linux/un.h>
38 #include <linux/uaccess.h>
39 #include <linux/inet.h>
40 #include <linux/idr.h>
41 #include <linux/file.h>
42 #include <net/9p/9p.h>
43 #include <linux/parser.h>
44 #include <net/9p/transport.h>
45 #include <linux/scatterlist.h>
46 #include <linux/virtio.h>
47 #include <linux/virtio_9p.h>
48
49 #define VIRTQUEUE_NUM 128
50
51 /* a single mutex to manage channel initialization and attachment */
52 static DECLARE_MUTEX(virtio_9p_lock);
53 /* global which tracks highest initialized channel */
54 static int chan_index;
55
56 #define P9_INIT_MAXTAG 16
57
58 #define REQ_STATUS_IDLE 0
59 #define REQ_STATUS_SENT 1
60 #define REQ_STATUS_RCVD 2
61 #define REQ_STATUS_FLSH 3
62
63 struct p9_req_t {
64 int status;
65 wait_queue_head_t *wq;
66 };
67
68 /* We keep all per-channel information in a structure.
69 * This structure is allocated within the devices dev->mem space.
70 * A pointer to the structure will get put in the transport private.
71 */
72 static struct virtio_chan {
73 bool initialized; /* channel is initialized */
74 bool inuse; /* channel is in use */
75
76 spinlock_t lock;
77
78 struct virtio_device *vdev;
79 struct virtqueue *vq;
80
81 struct p9_idpool *tagpool;
82 struct p9_req_t *reqs;
83 int max_tag;
84
85 /* Scatterlist: can be too big for stack. */
86 struct scatterlist sg[VIRTQUEUE_NUM];
87 } channels[MAX_9P_CHAN];
88
89 /* Lookup requests by tag */
90 static struct p9_req_t *p9_lookup_tag(struct virtio_chan *c, u16 tag)
91 {
92 /* This looks up the original request by tag so we know which
93 * buffer to read the data into */
94 tag++;
95
96 while (tag >= c->max_tag) {
97 int old_max = c->max_tag;
98 int count;
99
100 if (c->max_tag)
101 c->max_tag *= 2;
102 else
103 c->max_tag = P9_INIT_MAXTAG;
104
105 c->reqs = krealloc(c->reqs, sizeof(struct p9_req_t)*c->max_tag,
106 GFP_ATOMIC);
107 if (!c->reqs) {
108 printk(KERN_ERR "Couldn't grow tag array\n");
109 BUG();
110 }
111 for (count = old_max; count < c->max_tag; count++) {
112 c->reqs[count].status = REQ_STATUS_IDLE;
113 c->reqs[count].wq = kmalloc(sizeof(wait_queue_head_t),
114 GFP_ATOMIC);
115 if (!c->reqs[count].wq) {
116 printk(KERN_ERR "Couldn't grow tag array\n");
117 BUG();
118 }
119 init_waitqueue_head(c->reqs[count].wq);
120 }
121 }
122
123 return &c->reqs[tag];
124 }
125
126
127 /* How many bytes left in this page. */
128 static unsigned int rest_of_page(void *data)
129 {
130 return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
131 }
132
133 static void p9_virtio_close(struct p9_trans *trans)
134 {
135 struct virtio_chan *chan = trans->priv;
136 int count;
137 unsigned int flags;
138
139 spin_lock_irqsave(&chan->lock, flags);
140 p9_idpool_destroy(chan->tagpool);
141 for (count = 0; count < chan->max_tag; count++)
142 kfree(chan->reqs[count].wq);
143 kfree(chan->reqs);
144 chan->max_tag = 0;
145 spin_unlock_irqrestore(&chan->lock, flags);
146
147 down(&virtio_9p_lock);
148 chan->inuse = false;
149 up(&virtio_9p_lock);
150
151 kfree(trans);
152 }
153
154 static void req_done(struct virtqueue *vq)
155 {
156 struct virtio_chan *chan = vq->vdev->priv;
157 struct p9_fcall *rc;
158 unsigned int len;
159 unsigned long flags;
160 struct p9_req_t *req;
161
162 spin_lock_irqsave(&chan->lock, flags);
163 while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) {
164 req = p9_lookup_tag(chan, rc->tag);
165 req->status = REQ_STATUS_RCVD;
166 wake_up(req->wq);
167 }
168 /* In case queue is stopped waiting for more buffers. */
169 spin_unlock_irqrestore(&chan->lock, flags);
170 }
171
172 static int
173 pack_sg_list(struct scatterlist *sg, int start, int limit, char *data,
174 int count)
175 {
176 int s;
177 int index = start;
178
179 while (count) {
180 s = rest_of_page(data);
181 if (s > count)
182 s = count;
183 sg_set_buf(&sg[index++], data, s);
184 count -= s;
185 data += s;
186 BUG_ON(index > limit);
187 }
188
189 return index-start;
190 }
191
192 static int
193 p9_virtio_rpc(struct p9_trans *t, struct p9_fcall *tc, struct p9_fcall **rc)
194 {
195 int in, out;
196 int n, err, size;
197 struct virtio_chan *chan = t->priv;
198 char *rdata;
199 struct p9_req_t *req;
200 unsigned long flags;
201
202 if (*rc == NULL) {
203 *rc = kmalloc(sizeof(struct p9_fcall) + t->msize, GFP_KERNEL);
204 if (!*rc)
205 return -ENOMEM;
206 }
207
208 rdata = (char *)*rc+sizeof(struct p9_fcall);
209
210 n = P9_NOTAG;
211 if (tc->id != P9_TVERSION) {
212 n = p9_idpool_get(chan->tagpool);
213 if (n < 0)
214 return -ENOMEM;
215 }
216
217 spin_lock_irqsave(&chan->lock, flags);
218 req = p9_lookup_tag(chan, n);
219 spin_unlock_irqrestore(&chan->lock, flags);
220
221 p9_set_tag(tc, n);
222
223 P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio rpc tag %d\n", n);
224
225 out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, tc->sdata, tc->size);
226 in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata, t->msize);
227
228 req->status = REQ_STATUS_SENT;
229
230 if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, tc)) {
231 P9_DPRINTK(P9_DEBUG_TRANS,
232 "9p debug: virtio rpc add_buf returned failure");
233 return -EIO;
234 }
235
236 chan->vq->vq_ops->kick(chan->vq);
237
238 wait_event(*req->wq, req->status == REQ_STATUS_RCVD);
239
240 size = le32_to_cpu(*(__le32 *) rdata);
241
242 err = p9_deserialize_fcall(rdata, size, *rc, t->extended);
243 if (err < 0) {
244 P9_DPRINTK(P9_DEBUG_TRANS,
245 "9p debug: virtio rpc deserialize returned %d\n", err);
246 return err;
247 }
248
249 #ifdef CONFIG_NET_9P_DEBUG
250 if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
251 char buf[150];
252
253 p9_printfcall(buf, sizeof(buf), *rc, t->extended);
254 printk(KERN_NOTICE ">>> %p %s\n", t, buf);
255 }
256 #endif
257
258 if (n != P9_NOTAG && p9_idpool_check(n, chan->tagpool))
259 p9_idpool_put(n, chan->tagpool);
260
261 req->status = REQ_STATUS_IDLE;
262
263 return 0;
264 }
265
266 static int p9_virtio_probe(struct virtio_device *vdev)
267 {
268 int err;
269 struct virtio_chan *chan;
270 int index;
271
272 down(&virtio_9p_lock);
273 index = chan_index++;
274 chan = &channels[index];
275 up(&virtio_9p_lock);
276
277 if (chan_index > MAX_9P_CHAN) {
278 printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
279 BUG();
280 err = -ENOMEM;
281 goto fail;
282 }
283
284 chan->vdev = vdev;
285
286 /* We expect one virtqueue, for requests. */
287 chan->vq = vdev->config->find_vq(vdev, 0, req_done);
288 if (IS_ERR(chan->vq)) {
289 err = PTR_ERR(chan->vq);
290 goto out_free_vq;
291 }
292 chan->vq->vdev->priv = chan;
293 spin_lock_init(&chan->lock);
294
295 sg_init_table(chan->sg, VIRTQUEUE_NUM);
296
297 chan->inuse = false;
298 chan->initialized = true;
299 return 0;
300
301 out_free_vq:
302 vdev->config->del_vq(chan->vq);
303 fail:
304 down(&virtio_9p_lock);
305 chan_index--;
306 up(&virtio_9p_lock);
307 return err;
308 }
309
310 /* This sets up a transport channel for 9p communication. Right now
311 * we only match the first available channel, but eventually we couldlook up
312 * alternate channels by matching devname versus a virtio_config entry.
313 * We use a simple reference count mechanism to ensure that only a single
314 * mount has a channel open at a time. */
315 static struct p9_trans *
316 p9_virtio_create(const char *devname, char *args, int msize,
317 unsigned char extended)
318 {
319 struct p9_trans *trans;
320 struct virtio_chan *chan = channels;
321 int index = 0;
322
323 down(&virtio_9p_lock);
324 while (index < MAX_9P_CHAN) {
325 if (chan->initialized && !chan->inuse) {
326 chan->inuse = true;
327 break;
328 } else {
329 index++;
330 chan = &channels[index];
331 }
332 }
333 up(&virtio_9p_lock);
334
335 if (index >= MAX_9P_CHAN) {
336 printk(KERN_ERR "9p: no channels available\n");
337 return ERR_PTR(-ENODEV);
338 }
339
340 chan->tagpool = p9_idpool_create();
341 if (IS_ERR(chan->tagpool)) {
342 printk(KERN_ERR "9p: couldn't allocate tagpool\n");
343 return ERR_PTR(-ENOMEM);
344 }
345 p9_idpool_get(chan->tagpool); /* reserve tag 0 */
346 chan->max_tag = 0;
347 chan->reqs = NULL;
348
349 trans = kmalloc(sizeof(struct p9_trans), GFP_KERNEL);
350 if (!trans) {
351 printk(KERN_ERR "9p: couldn't allocate transport\n");
352 return ERR_PTR(-ENOMEM);
353 }
354 trans->extended = extended;
355 trans->msize = msize;
356 trans->close = p9_virtio_close;
357 trans->rpc = p9_virtio_rpc;
358 trans->priv = chan;
359
360 return trans;
361 }
362
363 static void p9_virtio_remove(struct virtio_device *vdev)
364 {
365 struct virtio_chan *chan = vdev->priv;
366
367 BUG_ON(chan->inuse);
368
369 if (chan->initialized) {
370 vdev->config->del_vq(chan->vq);
371 chan->initialized = false;
372 }
373 }
374
375 #define VIRTIO_ID_9P 9
376
377 static struct virtio_device_id id_table[] = {
378 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
379 { 0 },
380 };
381
382 /* The standard "struct lguest_driver": */
383 static struct virtio_driver p9_virtio_drv = {
384 .driver.name = KBUILD_MODNAME,
385 .driver.owner = THIS_MODULE,
386 .id_table = id_table,
387 .probe = p9_virtio_probe,
388 .remove = p9_virtio_remove,
389 };
390
391 static struct p9_trans_module p9_virtio_trans = {
392 .name = "virtio",
393 .create = p9_virtio_create,
394 .maxsize = PAGE_SIZE*16,
395 .def = 0,
396 };
397
398 /* The standard init function */
399 static int __init p9_virtio_init(void)
400 {
401 int count;
402
403 for (count = 0; count < MAX_9P_CHAN; count++)
404 channels[count].initialized = false;
405
406 v9fs_register_trans(&p9_virtio_trans);
407 return register_virtio_driver(&p9_virtio_drv);
408 }
409
410 static void __exit p9_virtio_cleanup(void)
411 {
412 unregister_virtio_driver(&p9_virtio_drv);
413 }
414
415 module_init(p9_virtio_init);
416 module_exit(p9_virtio_cleanup);
417
418 MODULE_DEVICE_TABLE(virtio, id_table);
419 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
420 MODULE_DESCRIPTION("Virtio 9p Transport");
421 MODULE_LICENSE("GPL");
422
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