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 <linux/slab.h> 41 #include <net/9p/9p.h> 42 #include <linux/parser.h> 43 #include <net/9p/client.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 DEFINE_MUTEX(virtio_9p_lock); 53 54 /** 55 * struct virtio_chan - per-instance transport information 56 * @initialized: whether the channel is initialized 57 * @inuse: whether the channel is in use 58 * @lock: protects multiple elements within this structure 59 * @client: client instance 60 * @vdev: virtio dev associated with this channel 61 * @vq: virtio queue associated with this channel 62 * @sg: scatter gather list which is used to pack a request (protected?) 63 * 64 * We keep all per-channel information in a structure. 65 * This structure is allocated within the devices dev->mem space. 66 * A pointer to the structure will get put in the transport private. 67 * 68 */ 69 70 struct virtio_chan { 71 bool inuse; 72 73 spinlock_t lock; 74 75 struct p9_client *client; 76 struct virtio_device *vdev; 77 struct virtqueue *vq; 78 int ring_bufs_avail; 79 wait_queue_head_t *vc_wq; 80 81 /* Scatterlist: can be too big for stack. */ 82 struct scatterlist sg[VIRTQUEUE_NUM]; 83 84 int tag_len; 85 /* 86 * tag name to identify a mount Non-null terminated 87 */ 88 char *tag; 89 90 struct list_head chan_list; 91 }; 92 93 static struct list_head virtio_chan_list; 94 95 /* How many bytes left in this page. */ 96 static unsigned int rest_of_page(void *data) 97 { 98 return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE); 99 } 100 101 /** 102 * p9_virtio_close - reclaim resources of a channel 103 * @client: client instance 104 * 105 * This reclaims a channel by freeing its resources and 106 * reseting its inuse flag. 107 * 108 */ 109 110 static void p9_virtio_close(struct p9_client *client) 111 { 112 struct virtio_chan *chan = client->trans; 113 114 mutex_lock(&virtio_9p_lock); 115 if (chan) 116 chan->inuse = false; 117 mutex_unlock(&virtio_9p_lock); 118 } 119 120 /** 121 * req_done - callback which signals activity from the server 122 * @vq: virtio queue activity was received on 123 * 124 * This notifies us that the server has triggered some activity 125 * on the virtio channel - most likely a response to request we 126 * sent. Figure out which requests now have responses and wake up 127 * those threads. 128 * 129 * Bugs: could do with some additional sanity checking, but appears to work. 130 * 131 */ 132 133 static void req_done(struct virtqueue *vq) 134 { 135 struct virtio_chan *chan = vq->vdev->priv; 136 struct p9_fcall *rc; 137 unsigned int len; 138 struct p9_req_t *req; 139 unsigned long flags; 140 141 P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n"); 142 143 do { 144 spin_lock_irqsave(&chan->lock, flags); 145 rc = virtqueue_get_buf(chan->vq, &len); 146 147 if (rc != NULL) { 148 if (!chan->ring_bufs_avail) { 149 chan->ring_bufs_avail = 1; 150 wake_up(chan->vc_wq); 151 } 152 spin_unlock_irqrestore(&chan->lock, flags); 153 P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc); 154 P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", 155 rc->tag); 156 req = p9_tag_lookup(chan->client, rc->tag); 157 req->status = REQ_STATUS_RCVD; 158 p9_client_cb(chan->client, req); 159 } else { 160 spin_unlock_irqrestore(&chan->lock, flags); 161 } 162 } while (rc != NULL); 163 } 164 165 /** 166 * pack_sg_list - pack a scatter gather list from a linear buffer 167 * @sg: scatter/gather list to pack into 168 * @start: which segment of the sg_list to start at 169 * @limit: maximum segment to pack data to 170 * @data: data to pack into scatter/gather list 171 * @count: amount of data to pack into the scatter/gather list 172 * 173 * sg_lists have multiple segments of various sizes. This will pack 174 * arbitrary data into an existing scatter gather list, segmenting the 175 * data as necessary within constraints. 176 * 177 */ 178 179 static int 180 pack_sg_list(struct scatterlist *sg, int start, int limit, char *data, 181 int count) 182 { 183 int s; 184 int index = start; 185 186 while (count) { 187 s = rest_of_page(data); 188 if (s > count) 189 s = count; 190 sg_set_buf(&sg[index++], data, s); 191 count -= s; 192 data += s; 193 BUG_ON(index > limit); 194 } 195 196 return index-start; 197 } 198 199 /* We don't currently allow canceling of virtio requests */ 200 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) 201 { 202 return 1; 203 } 204 205 /** 206 * p9_virtio_request - issue a request 207 * @client: client instance issuing the request 208 * @req: request to be issued 209 * 210 */ 211 212 static int 213 p9_virtio_request(struct p9_client *client, struct p9_req_t *req) 214 { 215 int in, out; 216 struct virtio_chan *chan = client->trans; 217 char *rdata = (char *)req->rc+sizeof(struct p9_fcall); 218 unsigned long flags; 219 int err; 220 221 P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n"); 222 223 req_retry: 224 req->status = REQ_STATUS_SENT; 225 226 spin_lock_irqsave(&chan->lock, flags); 227 out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata, 228 req->tc->size); 229 in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata, 230 client->msize); 231 232 err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc); 233 if (err < 0) { 234 if (err == -ENOSPC) { 235 chan->ring_bufs_avail = 0; 236 spin_unlock_irqrestore(&chan->lock, flags); 237 err = wait_event_interruptible(*chan->vc_wq, 238 chan->ring_bufs_avail); 239 if (err == -ERESTARTSYS) 240 return err; 241 242 P9_DPRINTK(P9_DEBUG_TRANS, "9p:Retry virtio request\n"); 243 goto req_retry; 244 } else { 245 spin_unlock_irqrestore(&chan->lock, flags); 246 P9_DPRINTK(P9_DEBUG_TRANS, 247 "9p debug: " 248 "virtio rpc add_buf returned failure"); 249 return -EIO; 250 } 251 } 252 253 virtqueue_kick(chan->vq); 254 spin_unlock_irqrestore(&chan->lock, flags); 255 256 P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n"); 257 return 0; 258 } 259 260 static ssize_t p9_mount_tag_show(struct device *dev, 261 struct device_attribute *attr, char *buf) 262 { 263 struct virtio_chan *chan; 264 struct virtio_device *vdev; 265 266 vdev = dev_to_virtio(dev); 267 chan = vdev->priv; 268 269 return snprintf(buf, chan->tag_len + 1, "%s", chan->tag); 270 } 271 272 static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL); 273 274 /** 275 * p9_virtio_probe - probe for existence of 9P virtio channels 276 * @vdev: virtio device to probe 277 * 278 * This probes for existing virtio channels. 279 * 280 */ 281 282 static int p9_virtio_probe(struct virtio_device *vdev) 283 { 284 __u16 tag_len; 285 char *tag; 286 int err; 287 struct virtio_chan *chan; 288 289 chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL); 290 if (!chan) { 291 printk(KERN_ERR "9p: Failed to allocate virtio 9P channel\n"); 292 err = -ENOMEM; 293 goto fail; 294 } 295 296 chan->vdev = vdev; 297 298 /* We expect one virtqueue, for requests. */ 299 chan->vq = virtio_find_single_vq(vdev, req_done, "requests"); 300 if (IS_ERR(chan->vq)) { 301 err = PTR_ERR(chan->vq); 302 goto out_free_vq; 303 } 304 chan->vq->vdev->priv = chan; 305 spin_lock_init(&chan->lock); 306 307 sg_init_table(chan->sg, VIRTQUEUE_NUM); 308 309 chan->inuse = false; 310 if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) { 311 vdev->config->get(vdev, 312 offsetof(struct virtio_9p_config, tag_len), 313 &tag_len, sizeof(tag_len)); 314 } else { 315 err = -EINVAL; 316 goto out_free_vq; 317 } 318 tag = kmalloc(tag_len, GFP_KERNEL); 319 if (!tag) { 320 err = -ENOMEM; 321 goto out_free_vq; 322 } 323 vdev->config->get(vdev, offsetof(struct virtio_9p_config, tag), 324 tag, tag_len); 325 chan->tag = tag; 326 chan->tag_len = tag_len; 327 err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 328 if (err) { 329 goto out_free_tag; 330 } 331 chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL); 332 if (!chan->vc_wq) { 333 err = -ENOMEM; 334 goto out_free_tag; 335 } 336 init_waitqueue_head(chan->vc_wq); 337 chan->ring_bufs_avail = 1; 338 339 mutex_lock(&virtio_9p_lock); 340 list_add_tail(&chan->chan_list, &virtio_chan_list); 341 mutex_unlock(&virtio_9p_lock); 342 return 0; 343 344 out_free_tag: 345 kfree(tag); 346 out_free_vq: 347 vdev->config->del_vqs(vdev); 348 kfree(chan); 349 fail: 350 return err; 351 } 352 353 354 /** 355 * p9_virtio_create - allocate a new virtio channel 356 * @client: client instance invoking this transport 357 * @devname: string identifying the channel to connect to (unused) 358 * @args: args passed from sys_mount() for per-transport options (unused) 359 * 360 * This sets up a transport channel for 9p communication. Right now 361 * we only match the first available channel, but eventually we couldlook up 362 * alternate channels by matching devname versus a virtio_config entry. 363 * We use a simple reference count mechanism to ensure that only a single 364 * mount has a channel open at a time. 365 * 366 */ 367 368 static int 369 p9_virtio_create(struct p9_client *client, const char *devname, char *args) 370 { 371 struct virtio_chan *chan; 372 int ret = -ENOENT; 373 int found = 0; 374 375 mutex_lock(&virtio_9p_lock); 376 list_for_each_entry(chan, &virtio_chan_list, chan_list) { 377 if (!strncmp(devname, chan->tag, chan->tag_len) && 378 strlen(devname) == chan->tag_len) { 379 if (!chan->inuse) { 380 chan->inuse = true; 381 found = 1; 382 break; 383 } 384 ret = -EBUSY; 385 } 386 } 387 mutex_unlock(&virtio_9p_lock); 388 389 if (!found) { 390 printk(KERN_ERR "9p: no channels available\n"); 391 return ret; 392 } 393 394 client->trans = (void *)chan; 395 client->status = Connected; 396 chan->client = client; 397 398 return 0; 399 } 400 401 /** 402 * p9_virtio_remove - clean up resources associated with a virtio device 403 * @vdev: virtio device to remove 404 * 405 */ 406 407 static void p9_virtio_remove(struct virtio_device *vdev) 408 { 409 struct virtio_chan *chan = vdev->priv; 410 411 BUG_ON(chan->inuse); 412 vdev->config->del_vqs(vdev); 413 414 mutex_lock(&virtio_9p_lock); 415 list_del(&chan->chan_list); 416 mutex_unlock(&virtio_9p_lock); 417 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 418 kfree(chan->tag); 419 kfree(chan->vc_wq); 420 kfree(chan); 421 422 } 423 424 static struct virtio_device_id id_table[] = { 425 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID }, 426 { 0 }, 427 }; 428 429 static unsigned int features[] = { 430 VIRTIO_9P_MOUNT_TAG, 431 }; 432 433 /* The standard "struct lguest_driver": */ 434 static struct virtio_driver p9_virtio_drv = { 435 .feature_table = features, 436 .feature_table_size = ARRAY_SIZE(features), 437 .driver.name = KBUILD_MODNAME, 438 .driver.owner = THIS_MODULE, 439 .id_table = id_table, 440 .probe = p9_virtio_probe, 441 .remove = p9_virtio_remove, 442 }; 443 444 static struct p9_trans_module p9_virtio_trans = { 445 .name = "virtio", 446 .create = p9_virtio_create, 447 .close = p9_virtio_close, 448 .request = p9_virtio_request, 449 .cancel = p9_virtio_cancel, 450 .maxsize = PAGE_SIZE*16, 451 .def = 0, 452 .owner = THIS_MODULE, 453 }; 454 455 /* The standard init function */ 456 static int __init p9_virtio_init(void) 457 { 458 INIT_LIST_HEAD(&virtio_chan_list); 459 460 v9fs_register_trans(&p9_virtio_trans); 461 return register_virtio_driver(&p9_virtio_drv); 462 } 463 464 static void __exit p9_virtio_cleanup(void) 465 { 466 unregister_virtio_driver(&p9_virtio_drv); 467 v9fs_unregister_trans(&p9_virtio_trans); 468 } 469 470 module_init(p9_virtio_init); 471 module_exit(p9_virtio_cleanup); 472 473 MODULE_DEVICE_TABLE(virtio, id_table); 474 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>"); 475 MODULE_DESCRIPTION("Virtio 9p Transport"); 476 MODULE_LICENSE("GPL"); 477