2 * The Guest 9p transport driver
4 * This is a block based transport driver based on the lguest block driver
9 * Copyright (C) 2007 Eric Van Hensbergen, IBM Corporation
11 * Based on virtio console driver
12 * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
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.
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.
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
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>
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>
49 #define VIRTQUEUE_NUM 128
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;
56 #define P9_INIT_MAXTAG 16
58 #define REQ_STATUS_IDLE 0
59 #define REQ_STATUS_SENT 1
60 #define REQ_STATUS_RCVD 2
61 #define REQ_STATUS_FLSH 3
65 wait_queue_head_t *wq;
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.
72 static struct virtio_chan {
73 bool initialized; /* channel is initialized */
74 bool inuse; /* channel is in use */
78 struct virtio_device *vdev;
81 struct p9_idpool *tagpool;
82 struct p9_req_t *reqs;
85 /* Scatterlist: can be too big for stack. */
86 struct scatterlist sg[VIRTQUEUE_NUM];
87 } channels[MAX_9P_CHAN];
89 /* Lookup requests by tag */
90 static struct p9_req_t *p9_lookup_tag(struct virtio_chan *c, u16 tag)
92 /* This looks up the original request by tag so we know which
93 * buffer to read the data into */
96 while (tag >= c->max_tag) {
97 int old_max = c->max_tag;
103 c->max_tag = P9_INIT_MAXTAG;
105 c->reqs = krealloc(c->reqs, sizeof(struct p9_req_t)*c->max_tag,
108 printk(KERN_ERR "Couldn't grow tag array\n");
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_t),
115 if (!c->reqs[count].wq) {
116 printk(KERN_ERR "Couldn't grow tag array\n");
119 init_waitqueue_head(c->reqs[count].wq);
123 return &c->reqs[tag];
127 /* How many bytes left in this page. */
128 static unsigned int rest_of_page(void *data)
130 return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
133 static void p9_virtio_close(struct p9_trans *trans)
135 struct virtio_chan *chan = trans->priv;
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);
145 spin_unlock_irqrestore(&chan->lock, flags);
147 down(&virtio_9p_lock);
154 static void req_done(struct virtqueue *vq)
156 struct virtio_chan *chan = vq->vdev->priv;
160 struct p9_req_t *req;
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;
168 /* In case queue is stopped waiting for more buffers. */
169 spin_unlock_irqrestore(&chan->lock, flags);
173 pack_sg_list(struct scatterlist *sg, int start, int limit, char *data,
180 s = rest_of_page(data);
183 sg_set_buf(&sg[index++], data, s);
194 p9_virtio_rpc(struct p9_trans *t, struct p9_fcall *tc, struct p9_fcall **rc)
198 struct virtio_chan *chan = t->priv;
200 struct p9_req_t *req;
204 *rc = kmalloc(sizeof(struct p9_fcall) + t->msize, GFP_KERNEL);
209 rdata = (char *)*rc+sizeof(struct p9_fcall);
212 if (tc->id != P9_TVERSION) {
213 n = p9_idpool_get(chan->tagpool);
218 spin_lock_irqsave(&chan->lock, flags);
219 req = p9_lookup_tag(chan, n);
220 spin_unlock_irqrestore(&chan->lock, flags);
224 P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio rpc tag %d\n", n);
226 out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, tc->sdata, tc->size);
227 in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata, t->msize);
229 req->status = REQ_STATUS_SENT;
231 if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, tc)) {
232 P9_DPRINTK(P9_DEBUG_TRANS,
233 "9p debug: virtio rpc add_buf returned failure");
237 chan->vq->vq_ops->kick(chan->vq);
239 wait_event(*req->wq, req->status == REQ_STATUS_RCVD);
241 size = le32_to_cpu(*(__le32 *) rdata);
243 err = p9_deserialize_fcall(rdata, size, *rc, t->extended);
245 P9_DPRINTK(P9_DEBUG_TRANS,
246 "9p debug: virtio rpc deserialize returned %d\n", err);
250 #ifdef CONFIG_NET_9P_DEBUG
251 if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
254 p9_printfcall(buf, sizeof(buf), *rc, t->extended);
255 printk(KERN_NOTICE ">>> %p %s\n", t, buf);
259 if (n != P9_NOTAG && p9_idpool_check(n, chan->tagpool))
260 p9_idpool_put(n, chan->tagpool);
262 req->status = REQ_STATUS_IDLE;
267 static int p9_virtio_probe(struct virtio_device *vdev)
270 struct virtio_chan *chan;
273 down(&virtio_9p_lock);
274 index = chan_index++;
275 chan = &channels[index];
278 if (chan_index > MAX_9P_CHAN) {
279 printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
287 /* We expect one virtqueue, for requests. */
288 chan->vq = vdev->config->find_vq(vdev, 0, req_done);
289 if (IS_ERR(chan->vq)) {
290 err = PTR_ERR(chan->vq);
293 chan->vq->vdev->priv = chan;
294 spin_lock_init(&chan->lock);
296 sg_init_table(chan->sg, VIRTQUEUE_NUM);
299 chan->initialized = true;
303 vdev->config->del_vq(chan->vq);
305 down(&virtio_9p_lock);
311 /* This sets up a transport channel for 9p communication. Right now
312 * we only match the first available channel, but eventually we couldlook up
313 * alternate channels by matching devname versus a virtio_config entry.
314 * We use a simple reference count mechanism to ensure that only a single
315 * mount has a channel open at a time. */
316 static struct p9_trans *
317 p9_virtio_create(const char *devname, char *args, int msize,
318 unsigned char extended)
320 struct p9_trans *trans;
321 struct virtio_chan *chan = channels;
324 down(&virtio_9p_lock);
325 while (index < MAX_9P_CHAN) {
326 if (chan->initialized && !chan->inuse) {
331 chan = &channels[index];
336 if (index >= MAX_9P_CHAN) {
337 printk(KERN_ERR "9p: no channels available\n");
338 return ERR_PTR(-ENODEV);
341 chan->tagpool = p9_idpool_create();
342 if (IS_ERR(chan->tagpool)) {
343 printk(KERN_ERR "9p: couldn't allocate tagpool\n");
344 return ERR_PTR(-ENOMEM);
346 p9_idpool_get(chan->tagpool); /* reserve tag 0 */
350 trans = kmalloc(sizeof(struct p9_trans), GFP_KERNEL);
352 printk(KERN_ERR "9p: couldn't allocate transport\n");
353 return ERR_PTR(-ENOMEM);
355 trans->extended = extended;
356 trans->msize = msize;
357 trans->close = p9_virtio_close;
358 trans->rpc = p9_virtio_rpc;
364 static void p9_virtio_remove(struct virtio_device *vdev)
366 struct virtio_chan *chan = vdev->priv;
370 if (chan->initialized) {
371 vdev->config->del_vq(chan->vq);
372 chan->initialized = false;
376 #define VIRTIO_ID_9P 9
378 static struct virtio_device_id id_table[] = {
379 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
383 /* The standard "struct lguest_driver": */
384 static struct virtio_driver p9_virtio_drv = {
385 .driver.name = KBUILD_MODNAME,
386 .driver.owner = THIS_MODULE,
387 .id_table = id_table,
388 .probe = p9_virtio_probe,
389 .remove = p9_virtio_remove,
392 static struct p9_trans_module p9_virtio_trans = {
394 .create = p9_virtio_create,
395 .maxsize = PAGE_SIZE*16,
399 /* The standard init function */
400 static int __init p9_virtio_init(void)
404 for (count = 0; count < MAX_9P_CHAN; count++)
405 channels[count].initialized = false;
407 v9fs_register_trans(&p9_virtio_trans);
408 return register_virtio_driver(&p9_virtio_drv);
411 static void __exit p9_virtio_cleanup(void)
413 unregister_virtio_driver(&p9_virtio_drv);
416 module_init(p9_virtio_init);
417 module_exit(p9_virtio_cleanup);
419 MODULE_DEVICE_TABLE(virtio, id_table);
420 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
421 MODULE_DESCRIPTION("Virtio 9p Transport");
422 MODULE_LICENSE("GPL");