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 <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> 47 48 #define VIRTQUEUE_NUM 128 49 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; 54 55 /** 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?) 66 * 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. 70 * 71 */ 72 73 static struct virtio_chan { 74 bool initialized; 75 bool inuse; 76 77 spinlock_t lock; 78 79 struct p9_client *client; 80 struct virtio_device *vdev; 81 struct virtqueue *vq; 82 83 /* Scatterlist: can be too big for stack. */ 84 struct scatterlist sg[VIRTQUEUE_NUM]; 85 } channels[MAX_9P_CHAN]; 86 87 /* How many bytes left in this page. */ 88 static unsigned int rest_of_page(void *data) 89 { 90 return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE); 91 } 92 93 /** 94 * p9_virtio_close - reclaim resources of a channel 95 * @trans: transport state 96 * 97 * This reclaims a channel by freeing its resources and 98 * reseting its inuse flag. 99 * 100 */ 101 102 static void p9_virtio_close(struct p9_client *client) 103 { 104 struct virtio_chan *chan = client->trans; 105 106 mutex_lock(&virtio_9p_lock); 107 chan->inuse = false; 108 mutex_unlock(&virtio_9p_lock); 109 } 110 111 /** 112 * req_done - callback which signals activity from the server 113 * @vq: virtio queue activity was received on 114 * 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 118 * those threads. 119 * 120 * Bugs: could do with some additional sanity checking, but appears to work. 121 * 122 */ 123 124 static void req_done(struct virtqueue *vq) 125 { 126 struct virtio_chan *chan = vq->vdev->priv; 127 struct p9_fcall *rc; 128 unsigned int len; 129 struct p9_req_t *req; 130 131 P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n"); 132 133 while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) { 134 P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc); 135 P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag); 136 req = p9_tag_lookup(chan->client, rc->tag); 137 req->status = REQ_STATUS_RCVD; 138 p9_client_cb(chan->client, req); 139 } 140 } 141 142 /** 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 149 * 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. 153 * 154 */ 155 156 static int 157 pack_sg_list(struct scatterlist *sg, int start, int limit, char *data, 158 int count) 159 { 160 int s; 161 int index = start; 162 163 while (count) { 164 s = rest_of_page(data); 165 if (s > count) 166 s = count; 167 sg_set_buf(&sg[index++], data, s); 168 count -= s; 169 data += s; 170 BUG_ON(index > limit); 171 } 172 173 return index-start; 174 } 175 176 /* We don't currently allow canceling of virtio requests */ 177 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) 178 { 179 return 1; 180 } 181 182 /** 183 * p9_virtio_request - issue a request 184 * @t: transport state 185 * @tc: &p9_fcall request to transmit 186 * @rc: &p9_fcall to put reponse into 187 * 188 */ 189 190 static int 191 p9_virtio_request(struct p9_client *client, struct p9_req_t *req) 192 { 193 int in, out; 194 struct virtio_chan *chan = client->trans; 195 char *rdata = (char *)req->rc+sizeof(struct p9_fcall); 196 197 P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n"); 198 199 out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata, 200 req->tc->size); 201 in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata, 202 client->msize); 203 204 req->status = REQ_STATUS_SENT; 205 206 if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, req->tc)) { 207 P9_DPRINTK(P9_DEBUG_TRANS, 208 "9p debug: virtio rpc add_buf returned failure"); 209 return -EIO; 210 } 211 212 chan->vq->vq_ops->kick(chan->vq); 213 214 P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n"); 215 return 0; 216 } 217 218 /** 219 * p9_virtio_probe - probe for existence of 9P virtio channels 220 * @vdev: virtio device to probe 221 * 222 * This probes for existing virtio channels. At present only 223 * a single channel is in use, so in the future more work may need 224 * to be done here. 225 * 226 */ 227 228 static int p9_virtio_probe(struct virtio_device *vdev) 229 { 230 int err; 231 struct virtio_chan *chan; 232 int index; 233 234 mutex_lock(&virtio_9p_lock); 235 index = chan_index++; 236 chan = &channels[index]; 237 mutex_unlock(&virtio_9p_lock); 238 239 if (chan_index > MAX_9P_CHAN) { 240 printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n"); 241 BUG(); 242 err = -ENOMEM; 243 goto fail; 244 } 245 246 chan->vdev = vdev; 247 248 /* We expect one virtqueue, for requests. */ 249 chan->vq = vdev->config->find_vq(vdev, 0, req_done); 250 if (IS_ERR(chan->vq)) { 251 err = PTR_ERR(chan->vq); 252 goto out_free_vq; 253 } 254 chan->vq->vdev->priv = chan; 255 spin_lock_init(&chan->lock); 256 257 sg_init_table(chan->sg, VIRTQUEUE_NUM); 258 259 chan->inuse = false; 260 chan->initialized = true; 261 return 0; 262 263 out_free_vq: 264 vdev->config->del_vq(chan->vq); 265 fail: 266 mutex_lock(&virtio_9p_lock); 267 chan_index--; 268 mutex_unlock(&virtio_9p_lock); 269 return err; 270 } 271 272 273 /** 274 * p9_virtio_create - allocate a new virtio channel 275 * @client: client instance invoking this transport 276 * @devname: string identifying the channel to connect to (unused) 277 * @args: args passed from sys_mount() for per-transport options (unused) 278 * 279 * This sets up a transport channel for 9p communication. Right now 280 * we only match the first available channel, but eventually we couldlook up 281 * alternate channels by matching devname versus a virtio_config entry. 282 * We use a simple reference count mechanism to ensure that only a single 283 * mount has a channel open at a time. 284 * 285 * Bugs: doesn't allow identification of a specific channel 286 * to allocate, channels are allocated sequentially. This was 287 * a pragmatic decision to get things rolling, but ideally some 288 * way of identifying the channel to attach to would be nice 289 * if we are going to support multiple channels. 290 * 291 */ 292 293 static int 294 p9_virtio_create(struct p9_client *client, const char *devname, char *args) 295 { 296 struct virtio_chan *chan = channels; 297 int index = 0; 298 299 mutex_lock(&virtio_9p_lock); 300 while (index < MAX_9P_CHAN) { 301 if (chan->initialized && !chan->inuse) { 302 chan->inuse = true; 303 break; 304 } else { 305 index++; 306 chan = &channels[index]; 307 } 308 } 309 mutex_unlock(&virtio_9p_lock); 310 311 if (index >= MAX_9P_CHAN) { 312 printk(KERN_ERR "9p: no channels available\n"); 313 return -ENODEV; 314 } 315 316 client->trans = (void *)chan; 317 chan->client = client; 318 319 return 0; 320 } 321 322 /** 323 * p9_virtio_remove - clean up resources associated with a virtio device 324 * @vdev: virtio device to remove 325 * 326 */ 327 328 static void p9_virtio_remove(struct virtio_device *vdev) 329 { 330 struct virtio_chan *chan = vdev->priv; 331 332 BUG_ON(chan->inuse); 333 334 if (chan->initialized) { 335 vdev->config->del_vq(chan->vq); 336 chan->initialized = false; 337 } 338 } 339 340 #define VIRTIO_ID_9P 9 341 342 static struct virtio_device_id id_table[] = { 343 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID }, 344 { 0 }, 345 }; 346 347 /* The standard "struct lguest_driver": */ 348 static struct virtio_driver p9_virtio_drv = { 349 .driver.name = KBUILD_MODNAME, 350 .driver.owner = THIS_MODULE, 351 .id_table = id_table, 352 .probe = p9_virtio_probe, 353 .remove = p9_virtio_remove, 354 }; 355 356 static struct p9_trans_module p9_virtio_trans = { 357 .name = "virtio", 358 .create = p9_virtio_create, 359 .close = p9_virtio_close, 360 .request = p9_virtio_request, 361 .cancel = p9_virtio_cancel, 362 .maxsize = PAGE_SIZE*16, 363 .def = 0, 364 .owner = THIS_MODULE, 365 }; 366 367 /* The standard init function */ 368 static int __init p9_virtio_init(void) 369 { 370 int count; 371 372 for (count = 0; count < MAX_9P_CHAN; count++) 373 channels[count].initialized = false; 374 375 v9fs_register_trans(&p9_virtio_trans); 376 return register_virtio_driver(&p9_virtio_drv); 377 } 378 379 static void __exit p9_virtio_cleanup(void) 380 { 381 unregister_virtio_driver(&p9_virtio_drv); 382 v9fs_unregister_trans(&p9_virtio_trans); 383 } 384 385 module_init(p9_virtio_init); 386 module_exit(p9_virtio_cleanup); 387 388 MODULE_DEVICE_TABLE(virtio, id_table); 389 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>"); 390 MODULE_DESCRIPTION("Virtio 9p Transport"); 391 MODULE_LICENSE("GPL"); 392