2 * The Virtio 9p transport driver
4 * This is a block based transport driver based on the lguest block driver
7 * Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
9 * Based on virtio console driver
10 * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
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.
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.
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
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>
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>
48 #define VIRTQUEUE_NUM 128
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;
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 * @vdev: virtio dev associated with this channel
61 * @vq: virtio queue associated with this channel
62 * @tagpool: accounting for tag ids (and request slots)
63 * @reqs: array of request slots
64 * @max_tag: current number of request_slots allocated
65 * @sg: scatter gather list which is used to pack a request (protected?)
67 * We keep all per-channel information in a structure.
68 * This structure is allocated within the devices dev->mem space.
69 * A pointer to the structure will get put in the transport private.
73 static struct virtio_chan {
79 struct p9_client *client;
80 struct virtio_device *vdev;
83 /* Scatterlist: can be too big for stack. */
84 struct scatterlist sg[VIRTQUEUE_NUM];
85 } channels[MAX_9P_CHAN];
87 /* How many bytes left in this page. */
88 static unsigned int rest_of_page(void *data)
90 return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
94 * p9_virtio_close - reclaim resources of a channel
95 * @trans: transport state
97 * This reclaims a channel by freeing its resources and
98 * reseting its inuse flag.
102 static void p9_virtio_close(struct p9_client *client)
104 struct virtio_chan *chan = client->trans;
106 mutex_lock(&virtio_9p_lock);
108 mutex_unlock(&virtio_9p_lock);
112 * req_done - callback which signals activity from the server
113 * @vq: virtio queue activity was received on
115 * This notifies us that the server has triggered some activity
116 * on the virtio channel - most likely a response to request we
117 * sent. Figure out which requests now have responses and wake up
120 * Bugs: could do with some additional sanity checking, but appears to work.
124 static void req_done(struct virtqueue *vq)
126 struct virtio_chan *chan = vq->vdev->priv;
130 struct p9_req_t *req;
132 spin_lock_irqsave(&chan->lock, flags);
133 while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) {
134 req = p9_tag_lookup(chan->client, rc->tag);
135 req->status = REQ_STATUS_RCVD;
138 /* In case queue is stopped waiting for more buffers. */
139 spin_unlock_irqrestore(&chan->lock, flags);
143 * pack_sg_list - pack a scatter gather list from a linear buffer
144 * @sg: scatter/gather list to pack into
145 * @start: which segment of the sg_list to start at
146 * @limit: maximum segment to pack data to
147 * @data: data to pack into scatter/gather list
148 * @count: amount of data to pack into the scatter/gather list
150 * sg_lists have multiple segments of various sizes. This will pack
151 * arbitrary data into an existing scatter gather list, segmenting the
152 * data as necessary within constraints.
157 pack_sg_list(struct scatterlist *sg, int start, int limit, char *data,
164 s = rest_of_page(data);
167 sg_set_buf(&sg[index++], data, s);
170 BUG_ON(index > limit);
177 * p9_virtio_rpc - issue a request and wait for a response
178 * @t: transport state
179 * @tc: &p9_fcall request to transmit
180 * @rc: &p9_fcall to put reponse into
185 p9_virtio_rpc(struct p9_client *c, struct p9_fcall *tc, struct p9_fcall **rc)
189 struct virtio_chan *chan = c->trans;
191 struct p9_req_t *req;
195 *rc = kmalloc(sizeof(struct p9_fcall) + c->msize, GFP_KERNEL);
200 rdata = (char *)*rc+sizeof(struct p9_fcall);
203 if (tc->id != P9_TVERSION) {
204 n = p9_idpool_get(c->tagpool);
209 spin_lock_irqsave(&chan->lock, flags);
210 req = p9_tag_alloc(c, n);
211 spin_unlock_irqrestore(&chan->lock, flags);
215 P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio rpc tag %d\n", n);
217 out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, tc->sdata, tc->size);
218 in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata, c->msize);
220 req->status = REQ_STATUS_SENT;
222 if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, tc)) {
223 P9_DPRINTK(P9_DEBUG_TRANS,
224 "9p debug: virtio rpc add_buf returned failure");
228 chan->vq->vq_ops->kick(chan->vq);
230 wait_event(*req->wq, req->status == REQ_STATUS_RCVD);
232 size = le32_to_cpu(*(__le32 *) rdata);
234 err = p9_deserialize_fcall(rdata, size, *rc, c->dotu);
236 P9_DPRINTK(P9_DEBUG_TRANS,
237 "9p debug: virtio rpc deserialize returned %d\n", err);
241 #ifdef CONFIG_NET_9P_DEBUG
242 if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
245 p9_printfcall(buf, sizeof(buf), *rc, c->dotu);
246 printk(KERN_NOTICE ">>> %p %s\n", c, buf);
250 if (n != P9_NOTAG && p9_idpool_check(n, c->tagpool))
251 p9_idpool_put(n, c->tagpool);
253 req->status = REQ_STATUS_IDLE;
259 * p9_virtio_probe - probe for existence of 9P virtio channels
260 * @vdev: virtio device to probe
262 * This probes for existing virtio channels. At present only
263 * a single channel is in use, so in the future more work may need
268 static int p9_virtio_probe(struct virtio_device *vdev)
271 struct virtio_chan *chan;
274 mutex_lock(&virtio_9p_lock);
275 index = chan_index++;
276 chan = &channels[index];
277 mutex_unlock(&virtio_9p_lock);
279 if (chan_index > MAX_9P_CHAN) {
280 printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
288 /* We expect one virtqueue, for requests. */
289 chan->vq = vdev->config->find_vq(vdev, 0, req_done);
290 if (IS_ERR(chan->vq)) {
291 err = PTR_ERR(chan->vq);
294 chan->vq->vdev->priv = chan;
295 spin_lock_init(&chan->lock);
297 sg_init_table(chan->sg, VIRTQUEUE_NUM);
300 chan->initialized = true;
304 vdev->config->del_vq(chan->vq);
306 mutex_lock(&virtio_9p_lock);
308 mutex_unlock(&virtio_9p_lock);
314 * p9_virtio_create - allocate a new virtio channel
315 * @client: client instance invoking this transport
316 * @devname: string identifying the channel to connect to (unused)
317 * @args: args passed from sys_mount() for per-transport options (unused)
319 * This sets up a transport channel for 9p communication. Right now
320 * we only match the first available channel, but eventually we couldlook up
321 * alternate channels by matching devname versus a virtio_config entry.
322 * We use a simple reference count mechanism to ensure that only a single
323 * mount has a channel open at a time.
325 * Bugs: doesn't allow identification of a specific channel
326 * to allocate, channels are allocated sequentially. This was
327 * a pragmatic decision to get things rolling, but ideally some
328 * way of identifying the channel to attach to would be nice
329 * if we are going to support multiple channels.
334 p9_virtio_create(struct p9_client *client, const char *devname, char *args)
336 struct virtio_chan *chan = channels;
339 mutex_lock(&virtio_9p_lock);
340 while (index < MAX_9P_CHAN) {
341 if (chan->initialized && !chan->inuse) {
346 chan = &channels[index];
349 mutex_unlock(&virtio_9p_lock);
351 if (index >= MAX_9P_CHAN) {
352 printk(KERN_ERR "9p: no channels available\n");
356 client->trans = (void *)chan;
357 chan->client = client;
363 * p9_virtio_remove - clean up resources associated with a virtio device
364 * @vdev: virtio device to remove
368 static void p9_virtio_remove(struct virtio_device *vdev)
370 struct virtio_chan *chan = vdev->priv;
374 if (chan->initialized) {
375 vdev->config->del_vq(chan->vq);
376 chan->initialized = false;
380 #define VIRTIO_ID_9P 9
382 static struct virtio_device_id id_table[] = {
383 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
387 /* The standard "struct lguest_driver": */
388 static struct virtio_driver p9_virtio_drv = {
389 .driver.name = KBUILD_MODNAME,
390 .driver.owner = THIS_MODULE,
391 .id_table = id_table,
392 .probe = p9_virtio_probe,
393 .remove = p9_virtio_remove,
396 static struct p9_trans_module p9_virtio_trans = {
398 .create = p9_virtio_create,
399 .close = p9_virtio_close,
400 .rpc = p9_virtio_rpc,
401 .maxsize = PAGE_SIZE*16,
403 .owner = THIS_MODULE,
406 /* The standard init function */
407 static int __init p9_virtio_init(void)
411 for (count = 0; count < MAX_9P_CHAN; count++)
412 channels[count].initialized = false;
414 v9fs_register_trans(&p9_virtio_trans);
415 return register_virtio_driver(&p9_virtio_drv);
418 static void __exit p9_virtio_cleanup(void)
420 unregister_virtio_driver(&p9_virtio_drv);
421 v9fs_unregister_trans(&p9_virtio_trans);
424 module_init(p9_virtio_init);
425 module_exit(p9_virtio_cleanup);
427 MODULE_DEVICE_TABLE(virtio, id_table);
428 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
429 MODULE_DESCRIPTION("Virtio 9p Transport");
430 MODULE_LICENSE("GPL");