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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 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 <linux/highmem.h> 43 #include <linux/slab.h> 44 #include <net/9p/9p.h> 45 #include <linux/parser.h> 46 #include <net/9p/client.h> 47 #include <net/9p/transport.h> 48 #include <linux/scatterlist.h> 49 #include <linux/swap.h> 50 #include <linux/virtio.h> 51 #include <linux/virtio_9p.h> 52 #include "trans_common.h" 53 54 #define VIRTQUEUE_NUM 128 55 56 /* a single mutex to manage channel initialization and attachment */ 57 static DEFINE_MUTEX(virtio_9p_lock); 58 static DECLARE_WAIT_QUEUE_HEAD(vp_wq); 59 static atomic_t vp_pinned = ATOMIC_INIT(0); 60 61 /** 62 * struct virtio_chan - per-instance transport information 63 * @initialized: whether the channel is initialized 64 * @inuse: whether the channel is in use 65 * @lock: protects multiple elements within this structure 66 * @client: client instance 67 * @vdev: virtio dev associated with this channel 68 * @vq: virtio queue associated with this channel 69 * @sg: scatter gather list which is used to pack a request (protected?) 70 * 71 * We keep all per-channel information in a structure. 72 * This structure is allocated within the devices dev->mem space. 73 * A pointer to the structure will get put in the transport private. 74 * 75 */ 76 77 struct virtio_chan { 78 bool inuse; 79 80 spinlock_t lock; 81 82 struct p9_client *client; 83 struct virtio_device *vdev; 84 struct virtqueue *vq; 85 int ring_bufs_avail; 86 wait_queue_head_t *vc_wq; 87 /* This is global limit. Since we don't have a global structure, 88 * will be placing it in each channel. 89 */ 90 unsigned long p9_max_pages; 91 /* Scatterlist: can be too big for stack. */ 92 struct scatterlist sg[VIRTQUEUE_NUM]; 93 94 int tag_len; 95 /* 96 * tag name to identify a mount Non-null terminated 97 */ 98 char *tag; 99 100 struct list_head chan_list; 101 }; 102 103 static struct list_head virtio_chan_list; 104 105 /* How many bytes left in this page. */ 106 static unsigned int rest_of_page(void *data) 107 { 108 return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE); 109 } 110 111 /** 112 * p9_virtio_close - reclaim resources of a channel 113 * @client: client instance 114 * 115 * This reclaims a channel by freeing its resources and 116 * reseting its inuse flag. 117 * 118 */ 119 120 static void p9_virtio_close(struct p9_client *client) 121 { 122 struct virtio_chan *chan = client->trans; 123 124 mutex_lock(&virtio_9p_lock); 125 if (chan) 126 chan->inuse = false; 127 mutex_unlock(&virtio_9p_lock); 128 } 129 130 /** 131 * req_done - callback which signals activity from the server 132 * @vq: virtio queue activity was received on 133 * 134 * This notifies us that the server has triggered some activity 135 * on the virtio channel - most likely a response to request we 136 * sent. Figure out which requests now have responses and wake up 137 * those threads. 138 * 139 * Bugs: could do with some additional sanity checking, but appears to work. 140 * 141 */ 142 143 static void req_done(struct virtqueue *vq) 144 { 145 struct virtio_chan *chan = vq->vdev->priv; 146 struct p9_fcall *rc; 147 unsigned int len; 148 struct p9_req_t *req; 149 unsigned long flags; 150 151 p9_debug(P9_DEBUG_TRANS, ": request done\n"); 152 153 while (1) { 154 spin_lock_irqsave(&chan->lock, flags); 155 rc = virtqueue_get_buf(chan->vq, &len); 156 if (rc == NULL) { 157 spin_unlock_irqrestore(&chan->lock, flags); 158 break; 159 } 160 chan->ring_bufs_avail = 1; 161 spin_unlock_irqrestore(&chan->lock, flags); 162 /* Wakeup if anyone waiting for VirtIO ring space. */ 163 wake_up(chan->vc_wq); 164 p9_debug(P9_DEBUG_TRANS, ": rc %p\n", rc); 165 p9_debug(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag); 166 req = p9_tag_lookup(chan->client, rc->tag); 167 p9_client_cb(chan->client, req, REQ_STATUS_RCVD); 168 } 169 } 170 171 /** 172 * pack_sg_list - pack a scatter gather list from a linear buffer 173 * @sg: scatter/gather list to pack into 174 * @start: which segment of the sg_list to start at 175 * @limit: maximum segment to pack data to 176 * @data: data to pack into scatter/gather list 177 * @count: amount of data to pack into the scatter/gather list 178 * 179 * sg_lists have multiple segments of various sizes. This will pack 180 * arbitrary data into an existing scatter gather list, segmenting the 181 * data as necessary within constraints. 182 * 183 */ 184 185 static int pack_sg_list(struct scatterlist *sg, int start, 186 int limit, char *data, int count) 187 { 188 int s; 189 int index = start; 190 191 while (count) { 192 s = rest_of_page(data); 193 if (s > count) 194 s = count; 195 BUG_ON(index > limit); 196 /* Make sure we don't terminate early. */ 197 sg_unmark_end(&sg[index]); 198 sg_set_buf(&sg[index++], data, s); 199 count -= s; 200 data += s; 201 } 202 if (index-start) 203 sg_mark_end(&sg[index - 1]); 204 return index-start; 205 } 206 207 /* We don't currently allow canceling of virtio requests */ 208 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) 209 { 210 return 1; 211 } 212 213 /** 214 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer, 215 * this takes a list of pages. 216 * @sg: scatter/gather list to pack into 217 * @start: which segment of the sg_list to start at 218 * @pdata: a list of pages to add into sg. 219 * @nr_pages: number of pages to pack into the scatter/gather list 220 * @data: data to pack into scatter/gather list 221 * @count: amount of data to pack into the scatter/gather list 222 */ 223 static int 224 pack_sg_list_p(struct scatterlist *sg, int start, int limit, 225 struct page **pdata, int nr_pages, char *data, int count) 226 { 227 int i = 0, s; 228 int data_off; 229 int index = start; 230 231 BUG_ON(nr_pages > (limit - start)); 232 /* 233 * if the first page doesn't start at 234 * page boundary find the offset 235 */ 236 data_off = offset_in_page(data); 237 while (nr_pages) { 238 s = rest_of_page(data); 239 if (s > count) 240 s = count; 241 /* Make sure we don't terminate early. */ 242 sg_unmark_end(&sg[index]); 243 sg_set_page(&sg[index++], pdata[i++], s, data_off); 244 data_off = 0; 245 data += s; 246 count -= s; 247 nr_pages--; 248 } 249 250 if (index-start) 251 sg_mark_end(&sg[index - 1]); 252 return index - start; 253 } 254 255 /** 256 * p9_virtio_request - issue a request 257 * @client: client instance issuing the request 258 * @req: request to be issued 259 * 260 */ 261 262 static int 263 p9_virtio_request(struct p9_client *client, struct p9_req_t *req) 264 { 265 int err; 266 int in, out, out_sgs, in_sgs; 267 unsigned long flags; 268 struct virtio_chan *chan = client->trans; 269 struct scatterlist *sgs[2]; 270 271 p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n"); 272 273 req->status = REQ_STATUS_SENT; 274 req_retry: 275 spin_lock_irqsave(&chan->lock, flags); 276 277 out_sgs = in_sgs = 0; 278 /* Handle out VirtIO ring buffers */ 279 out = pack_sg_list(chan->sg, 0, 280 VIRTQUEUE_NUM, req->tc->sdata, req->tc->size); 281 if (out) 282 sgs[out_sgs++] = chan->sg; 283 284 in = pack_sg_list(chan->sg, out, 285 VIRTQUEUE_NUM, req->rc->sdata, req->rc->capacity); 286 if (in) 287 sgs[out_sgs + in_sgs++] = chan->sg + out; 288 289 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req->tc, 290 GFP_ATOMIC); 291 if (err < 0) { 292 if (err == -ENOSPC) { 293 chan->ring_bufs_avail = 0; 294 spin_unlock_irqrestore(&chan->lock, flags); 295 err = wait_event_interruptible(*chan->vc_wq, 296 chan->ring_bufs_avail); 297 if (err == -ERESTARTSYS) 298 return err; 299 300 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 301 goto req_retry; 302 } else { 303 spin_unlock_irqrestore(&chan->lock, flags); 304 p9_debug(P9_DEBUG_TRANS, 305 "virtio rpc add_sgs returned failure\n"); 306 return -EIO; 307 } 308 } 309 virtqueue_kick(chan->vq); 310 spin_unlock_irqrestore(&chan->lock, flags); 311 312 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 313 return 0; 314 } 315 316 static int p9_get_mapped_pages(struct virtio_chan *chan, 317 struct page **pages, char *data, 318 int nr_pages, int write, int kern_buf) 319 { 320 int err; 321 if (!kern_buf) { 322 /* 323 * We allow only p9_max_pages pinned. We wait for the 324 * Other zc request to finish here 325 */ 326 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) { 327 err = wait_event_interruptible(vp_wq, 328 (atomic_read(&vp_pinned) < chan->p9_max_pages)); 329 if (err == -ERESTARTSYS) 330 return err; 331 } 332 err = p9_payload_gup(data, &nr_pages, pages, write); 333 if (err < 0) 334 return err; 335 atomic_add(nr_pages, &vp_pinned); 336 } else { 337 /* kernel buffer, no need to pin pages */ 338 int s, index = 0; 339 int count = nr_pages; 340 while (nr_pages) { 341 s = rest_of_page(data); 342 if (is_vmalloc_addr(data)) 343 pages[index++] = vmalloc_to_page(data); 344 else 345 pages[index++] = kmap_to_page(data); 346 data += s; 347 nr_pages--; 348 } 349 nr_pages = count; 350 } 351 return nr_pages; 352 } 353 354 /** 355 * p9_virtio_zc_request - issue a zero copy request 356 * @client: client instance issuing the request 357 * @req: request to be issued 358 * @uidata: user bffer that should be ued for zero copy read 359 * @uodata: user buffer that shoud be user for zero copy write 360 * @inlen: read buffer size 361 * @olen: write buffer size 362 * @hdrlen: reader header size, This is the size of response protocol data 363 * 364 */ 365 static int 366 p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req, 367 char *uidata, char *uodata, int inlen, 368 int outlen, int in_hdr_len, int kern_buf) 369 { 370 int in, out, err, out_sgs, in_sgs; 371 unsigned long flags; 372 int in_nr_pages = 0, out_nr_pages = 0; 373 struct page **in_pages = NULL, **out_pages = NULL; 374 struct virtio_chan *chan = client->trans; 375 struct scatterlist *sgs[4]; 376 377 p9_debug(P9_DEBUG_TRANS, "virtio request\n"); 378 379 if (uodata) { 380 out_nr_pages = p9_nr_pages(uodata, outlen); 381 out_pages = kmalloc(sizeof(struct page *) * out_nr_pages, 382 GFP_NOFS); 383 if (!out_pages) { 384 err = -ENOMEM; 385 goto err_out; 386 } 387 out_nr_pages = p9_get_mapped_pages(chan, out_pages, uodata, 388 out_nr_pages, 0, kern_buf); 389 if (out_nr_pages < 0) { 390 err = out_nr_pages; 391 kfree(out_pages); 392 out_pages = NULL; 393 goto err_out; 394 } 395 } 396 if (uidata) { 397 in_nr_pages = p9_nr_pages(uidata, inlen); 398 in_pages = kmalloc(sizeof(struct page *) * in_nr_pages, 399 GFP_NOFS); 400 if (!in_pages) { 401 err = -ENOMEM; 402 goto err_out; 403 } 404 in_nr_pages = p9_get_mapped_pages(chan, in_pages, uidata, 405 in_nr_pages, 1, kern_buf); 406 if (in_nr_pages < 0) { 407 err = in_nr_pages; 408 kfree(in_pages); 409 in_pages = NULL; 410 goto err_out; 411 } 412 } 413 req->status = REQ_STATUS_SENT; 414 req_retry_pinned: 415 spin_lock_irqsave(&chan->lock, flags); 416 417 out_sgs = in_sgs = 0; 418 419 /* out data */ 420 out = pack_sg_list(chan->sg, 0, 421 VIRTQUEUE_NUM, req->tc->sdata, req->tc->size); 422 423 if (out) 424 sgs[out_sgs++] = chan->sg; 425 426 if (out_pages) { 427 sgs[out_sgs++] = chan->sg + out; 428 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM, 429 out_pages, out_nr_pages, uodata, outlen); 430 } 431 432 /* 433 * Take care of in data 434 * For example TREAD have 11. 435 * 11 is the read/write header = PDU Header(7) + IO Size (4). 436 * Arrange in such a way that server places header in the 437 * alloced memory and payload onto the user buffer. 438 */ 439 in = pack_sg_list(chan->sg, out, 440 VIRTQUEUE_NUM, req->rc->sdata, in_hdr_len); 441 if (in) 442 sgs[out_sgs + in_sgs++] = chan->sg + out; 443 444 if (in_pages) { 445 sgs[out_sgs + in_sgs++] = chan->sg + out + in; 446 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM, 447 in_pages, in_nr_pages, uidata, inlen); 448 } 449 450 BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs)); 451 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req->tc, 452 GFP_ATOMIC); 453 if (err < 0) { 454 if (err == -ENOSPC) { 455 chan->ring_bufs_avail = 0; 456 spin_unlock_irqrestore(&chan->lock, flags); 457 err = wait_event_interruptible(*chan->vc_wq, 458 chan->ring_bufs_avail); 459 if (err == -ERESTARTSYS) 460 goto err_out; 461 462 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 463 goto req_retry_pinned; 464 } else { 465 spin_unlock_irqrestore(&chan->lock, flags); 466 p9_debug(P9_DEBUG_TRANS, 467 "virtio rpc add_sgs returned failure\n"); 468 err = -EIO; 469 goto err_out; 470 } 471 } 472 virtqueue_kick(chan->vq); 473 spin_unlock_irqrestore(&chan->lock, flags); 474 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 475 err = wait_event_interruptible(*req->wq, 476 req->status >= REQ_STATUS_RCVD); 477 /* 478 * Non kernel buffers are pinned, unpin them 479 */ 480 err_out: 481 if (!kern_buf) { 482 if (in_pages) { 483 p9_release_pages(in_pages, in_nr_pages); 484 atomic_sub(in_nr_pages, &vp_pinned); 485 } 486 if (out_pages) { 487 p9_release_pages(out_pages, out_nr_pages); 488 atomic_sub(out_nr_pages, &vp_pinned); 489 } 490 /* wakeup anybody waiting for slots to pin pages */ 491 wake_up(&vp_wq); 492 } 493 kfree(in_pages); 494 kfree(out_pages); 495 return err; 496 } 497 498 static ssize_t p9_mount_tag_show(struct device *dev, 499 struct device_attribute *attr, char *buf) 500 { 501 struct virtio_chan *chan; 502 struct virtio_device *vdev; 503 504 vdev = dev_to_virtio(dev); 505 chan = vdev->priv; 506 507 return snprintf(buf, chan->tag_len + 1, "%s", chan->tag); 508 } 509 510 static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL); 511 512 /** 513 * p9_virtio_probe - probe for existence of 9P virtio channels 514 * @vdev: virtio device to probe 515 * 516 * This probes for existing virtio channels. 517 * 518 */ 519 520 static int p9_virtio_probe(struct virtio_device *vdev) 521 { 522 __u16 tag_len; 523 char *tag; 524 int err; 525 struct virtio_chan *chan; 526 527 chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL); 528 if (!chan) { 529 pr_err("Failed to allocate virtio 9P channel\n"); 530 err = -ENOMEM; 531 goto fail; 532 } 533 534 chan->vdev = vdev; 535 536 /* We expect one virtqueue, for requests. */ 537 chan->vq = virtio_find_single_vq(vdev, req_done, "requests"); 538 if (IS_ERR(chan->vq)) { 539 err = PTR_ERR(chan->vq); 540 goto out_free_vq; 541 } 542 chan->vq->vdev->priv = chan; 543 spin_lock_init(&chan->lock); 544 545 sg_init_table(chan->sg, VIRTQUEUE_NUM); 546 547 chan->inuse = false; 548 if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) { 549 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len); 550 } else { 551 err = -EINVAL; 552 goto out_free_vq; 553 } 554 tag = kmalloc(tag_len, GFP_KERNEL); 555 if (!tag) { 556 err = -ENOMEM; 557 goto out_free_vq; 558 } 559 560 virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag), 561 tag, tag_len); 562 chan->tag = tag; 563 chan->tag_len = tag_len; 564 err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 565 if (err) { 566 goto out_free_tag; 567 } 568 chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL); 569 if (!chan->vc_wq) { 570 err = -ENOMEM; 571 goto out_free_tag; 572 } 573 init_waitqueue_head(chan->vc_wq); 574 chan->ring_bufs_avail = 1; 575 /* Ceiling limit to avoid denial of service attacks */ 576 chan->p9_max_pages = nr_free_buffer_pages()/4; 577 578 mutex_lock(&virtio_9p_lock); 579 list_add_tail(&chan->chan_list, &virtio_chan_list); 580 mutex_unlock(&virtio_9p_lock); 581 582 /* Let udev rules use the new mount_tag attribute. */ 583 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); 584 585 return 0; 586 587 out_free_tag: 588 kfree(tag); 589 out_free_vq: 590 vdev->config->del_vqs(vdev); 591 kfree(chan); 592 fail: 593 return err; 594 } 595 596 597 /** 598 * p9_virtio_create - allocate a new virtio channel 599 * @client: client instance invoking this transport 600 * @devname: string identifying the channel to connect to (unused) 601 * @args: args passed from sys_mount() for per-transport options (unused) 602 * 603 * This sets up a transport channel for 9p communication. Right now 604 * we only match the first available channel, but eventually we couldlook up 605 * alternate channels by matching devname versus a virtio_config entry. 606 * We use a simple reference count mechanism to ensure that only a single 607 * mount has a channel open at a time. 608 * 609 */ 610 611 static int 612 p9_virtio_create(struct p9_client *client, const char *devname, char *args) 613 { 614 struct virtio_chan *chan; 615 int ret = -ENOENT; 616 int found = 0; 617 618 mutex_lock(&virtio_9p_lock); 619 list_for_each_entry(chan, &virtio_chan_list, chan_list) { 620 if (!strncmp(devname, chan->tag, chan->tag_len) && 621 strlen(devname) == chan->tag_len) { 622 if (!chan->inuse) { 623 chan->inuse = true; 624 found = 1; 625 break; 626 } 627 ret = -EBUSY; 628 } 629 } 630 mutex_unlock(&virtio_9p_lock); 631 632 if (!found) { 633 pr_err("no channels available\n"); 634 return ret; 635 } 636 637 client->trans = (void *)chan; 638 client->status = Connected; 639 chan->client = client; 640 641 return 0; 642 } 643 644 /** 645 * p9_virtio_remove - clean up resources associated with a virtio device 646 * @vdev: virtio device to remove 647 * 648 */ 649 650 static void p9_virtio_remove(struct virtio_device *vdev) 651 { 652 struct virtio_chan *chan = vdev->priv; 653 654 if (chan->inuse) 655 p9_virtio_close(chan->client); 656 vdev->config->del_vqs(vdev); 657 658 mutex_lock(&virtio_9p_lock); 659 list_del(&chan->chan_list); 660 mutex_unlock(&virtio_9p_lock); 661 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 662 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); 663 kfree(chan->tag); 664 kfree(chan->vc_wq); 665 kfree(chan); 666 667 } 668 669 static struct virtio_device_id id_table[] = { 670 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID }, 671 { 0 }, 672 }; 673 674 static unsigned int features[] = { 675 VIRTIO_9P_MOUNT_TAG, 676 }; 677 678 /* The standard "struct lguest_driver": */ 679 static struct virtio_driver p9_virtio_drv = { 680 .feature_table = features, 681 .feature_table_size = ARRAY_SIZE(features), 682 .driver.name = KBUILD_MODNAME, 683 .driver.owner = THIS_MODULE, 684 .id_table = id_table, 685 .probe = p9_virtio_probe, 686 .remove = p9_virtio_remove, 687 }; 688 689 static struct p9_trans_module p9_virtio_trans = { 690 .name = "virtio", 691 .create = p9_virtio_create, 692 .close = p9_virtio_close, 693 .request = p9_virtio_request, 694 .zc_request = p9_virtio_zc_request, 695 .cancel = p9_virtio_cancel, 696 /* 697 * We leave one entry for input and one entry for response 698 * headers. We also skip one more entry to accomodate, address 699 * that are not at page boundary, that can result in an extra 700 * page in zero copy. 701 */ 702 .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3), 703 .def = 1, 704 .owner = THIS_MODULE, 705 }; 706 707 /* The standard init function */ 708 static int __init p9_virtio_init(void) 709 { 710 INIT_LIST_HEAD(&virtio_chan_list); 711 712 v9fs_register_trans(&p9_virtio_trans); 713 return register_virtio_driver(&p9_virtio_drv); 714 } 715 716 static void __exit p9_virtio_cleanup(void) 717 { 718 unregister_virtio_driver(&p9_virtio_drv); 719 v9fs_unregister_trans(&p9_virtio_trans); 720 } 721 722 module_init(p9_virtio_init); 723 module_exit(p9_virtio_cleanup); 724 725 MODULE_DEVICE_TABLE(virtio, id_table); 726 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>"); 727 MODULE_DESCRIPTION("Virtio 9p Transport"); 728 MODULE_LICENSE("GPL"); 729