1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * The Virtio 9p transport driver 4 * 5 * This is a block based transport driver based on the lguest block driver 6 * code. 7 * 8 * Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation 9 * 10 * Based on virtio console driver 11 * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation 12 */ 13 14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 15 16 #include <linux/in.h> 17 #include <linux/module.h> 18 #include <linux/net.h> 19 #include <linux/ipv6.h> 20 #include <linux/errno.h> 21 #include <linux/kernel.h> 22 #include <linux/un.h> 23 #include <linux/uaccess.h> 24 #include <linux/inet.h> 25 #include <linux/idr.h> 26 #include <linux/file.h> 27 #include <linux/highmem.h> 28 #include <linux/slab.h> 29 #include <net/9p/9p.h> 30 #include <linux/parser.h> 31 #include <net/9p/client.h> 32 #include <net/9p/transport.h> 33 #include <linux/scatterlist.h> 34 #include <linux/swap.h> 35 #include <linux/virtio.h> 36 #include <linux/virtio_9p.h> 37 #include "trans_common.h" 38 39 #define VIRTQUEUE_NUM 128 40 41 /* a single mutex to manage channel initialization and attachment */ 42 static DEFINE_MUTEX(virtio_9p_lock); 43 static DECLARE_WAIT_QUEUE_HEAD(vp_wq); 44 static atomic_t vp_pinned = ATOMIC_INIT(0); 45 46 /** 47 * struct virtio_chan - per-instance transport information 48 * @inuse: whether the channel is in use 49 * @lock: protects multiple elements within this structure 50 * @client: client instance 51 * @vdev: virtio dev associated with this channel 52 * @vq: virtio queue associated with this channel 53 * @ring_bufs_avail: flag to indicate there is some available in the ring buf 54 * @vc_wq: wait queue for waiting for thing to be added to ring buf 55 * @p9_max_pages: maximum number of pinned pages 56 * @sg: scatter gather list which is used to pack a request (protected?) 57 * @chan_list: linked list of channels 58 * 59 * We keep all per-channel information in a structure. 60 * This structure is allocated within the devices dev->mem space. 61 * A pointer to the structure will get put in the transport private. 62 * 63 */ 64 65 struct virtio_chan { 66 bool inuse; 67 68 spinlock_t lock; 69 70 struct p9_client *client; 71 struct virtio_device *vdev; 72 struct virtqueue *vq; 73 int ring_bufs_avail; 74 wait_queue_head_t *vc_wq; 75 /* This is global limit. Since we don't have a global structure, 76 * will be placing it in each channel. 77 */ 78 unsigned long p9_max_pages; 79 /* Scatterlist: can be too big for stack. */ 80 struct scatterlist sg[VIRTQUEUE_NUM]; 81 /** 82 * @tag: name to identify a mount null terminated 83 */ 84 char *tag; 85 86 struct list_head chan_list; 87 }; 88 89 static struct list_head virtio_chan_list; 90 91 /* How many bytes left in this page. */ 92 static unsigned int rest_of_page(void *data) 93 { 94 return PAGE_SIZE - offset_in_page(data); 95 } 96 97 /** 98 * p9_virtio_close - reclaim resources of a channel 99 * @client: client instance 100 * 101 * This reclaims a channel by freeing its resources and 102 * resetting its inuse flag. 103 * 104 */ 105 106 static void p9_virtio_close(struct p9_client *client) 107 { 108 struct virtio_chan *chan = client->trans; 109 110 mutex_lock(&virtio_9p_lock); 111 if (chan) 112 chan->inuse = false; 113 mutex_unlock(&virtio_9p_lock); 114 } 115 116 /** 117 * req_done - callback which signals activity from the server 118 * @vq: virtio queue activity was received on 119 * 120 * This notifies us that the server has triggered some activity 121 * on the virtio channel - most likely a response to request we 122 * sent. Figure out which requests now have responses and wake up 123 * those threads. 124 * 125 * Bugs: could do with some additional sanity checking, but appears to work. 126 * 127 */ 128 129 static void req_done(struct virtqueue *vq) 130 { 131 struct virtio_chan *chan = vq->vdev->priv; 132 unsigned int len; 133 struct p9_req_t *req; 134 bool need_wakeup = false; 135 unsigned long flags; 136 137 p9_debug(P9_DEBUG_TRANS, ": request done\n"); 138 139 spin_lock_irqsave(&chan->lock, flags); 140 while ((req = virtqueue_get_buf(chan->vq, &len)) != NULL) { 141 if (!chan->ring_bufs_avail) { 142 chan->ring_bufs_avail = 1; 143 need_wakeup = true; 144 } 145 146 if (len) { 147 req->rc.size = len; 148 p9_client_cb(chan->client, req, REQ_STATUS_RCVD); 149 } 150 } 151 spin_unlock_irqrestore(&chan->lock, flags); 152 /* Wakeup if anyone waiting for VirtIO ring space. */ 153 if (need_wakeup) 154 wake_up(chan->vc_wq); 155 } 156 157 /** 158 * pack_sg_list - pack a scatter gather list from a linear buffer 159 * @sg: scatter/gather list to pack into 160 * @start: which segment of the sg_list to start at 161 * @limit: maximum segment to pack data to 162 * @data: data to pack into scatter/gather list 163 * @count: amount of data to pack into the scatter/gather list 164 * 165 * sg_lists have multiple segments of various sizes. This will pack 166 * arbitrary data into an existing scatter gather list, segmenting the 167 * data as necessary within constraints. 168 * 169 */ 170 171 static int pack_sg_list(struct scatterlist *sg, int start, 172 int limit, char *data, int count) 173 { 174 int s; 175 int index = start; 176 177 while (count) { 178 s = rest_of_page(data); 179 if (s > count) 180 s = count; 181 BUG_ON(index >= limit); 182 /* Make sure we don't terminate early. */ 183 sg_unmark_end(&sg[index]); 184 sg_set_buf(&sg[index++], data, s); 185 count -= s; 186 data += s; 187 } 188 if (index-start) 189 sg_mark_end(&sg[index - 1]); 190 return index-start; 191 } 192 193 /* We don't currently allow canceling of virtio requests */ 194 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) 195 { 196 return 1; 197 } 198 199 /* Reply won't come, so drop req ref */ 200 static int p9_virtio_cancelled(struct p9_client *client, struct p9_req_t *req) 201 { 202 p9_req_put(req); 203 return 0; 204 } 205 206 /** 207 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer, 208 * this takes a list of pages. 209 * @sg: scatter/gather list to pack into 210 * @start: which segment of the sg_list to start at 211 * @limit: maximum number of pages in sg list. 212 * @pdata: a list of pages to add into sg. 213 * @nr_pages: number of pages to pack into the scatter/gather list 214 * @offs: amount of data in the beginning of first page _not_ to pack 215 * @count: amount of data to pack into the scatter/gather list 216 */ 217 static int 218 pack_sg_list_p(struct scatterlist *sg, int start, int limit, 219 struct page **pdata, int nr_pages, size_t offs, int count) 220 { 221 int i = 0, s; 222 int data_off = offs; 223 int index = start; 224 225 BUG_ON(nr_pages > (limit - start)); 226 /* 227 * if the first page doesn't start at 228 * page boundary find the offset 229 */ 230 while (nr_pages) { 231 s = PAGE_SIZE - data_off; 232 if (s > count) 233 s = count; 234 BUG_ON(index >= limit); 235 /* Make sure we don't terminate early. */ 236 sg_unmark_end(&sg[index]); 237 sg_set_page(&sg[index++], pdata[i++], s, data_off); 238 data_off = 0; 239 count -= s; 240 nr_pages--; 241 } 242 243 if (index-start) 244 sg_mark_end(&sg[index - 1]); 245 return index - start; 246 } 247 248 /** 249 * p9_virtio_request - issue a request 250 * @client: client instance issuing the request 251 * @req: request to be issued 252 * 253 */ 254 255 static int 256 p9_virtio_request(struct p9_client *client, struct p9_req_t *req) 257 { 258 int err; 259 int in, out, out_sgs, in_sgs; 260 unsigned long flags; 261 struct virtio_chan *chan = client->trans; 262 struct scatterlist *sgs[2]; 263 264 p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n"); 265 266 req->status = REQ_STATUS_SENT; 267 req_retry: 268 spin_lock_irqsave(&chan->lock, flags); 269 270 out_sgs = in_sgs = 0; 271 /* Handle out VirtIO ring buffers */ 272 out = pack_sg_list(chan->sg, 0, 273 VIRTQUEUE_NUM, req->tc.sdata, req->tc.size); 274 if (out) 275 sgs[out_sgs++] = chan->sg; 276 277 in = pack_sg_list(chan->sg, out, 278 VIRTQUEUE_NUM, req->rc.sdata, req->rc.capacity); 279 if (in) 280 sgs[out_sgs + in_sgs++] = chan->sg + out; 281 282 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req, 283 GFP_ATOMIC); 284 if (err < 0) { 285 if (err == -ENOSPC) { 286 chan->ring_bufs_avail = 0; 287 spin_unlock_irqrestore(&chan->lock, flags); 288 err = wait_event_killable(*chan->vc_wq, 289 chan->ring_bufs_avail); 290 if (err == -ERESTARTSYS) 291 return err; 292 293 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 294 goto req_retry; 295 } else { 296 spin_unlock_irqrestore(&chan->lock, flags); 297 p9_debug(P9_DEBUG_TRANS, 298 "virtio rpc add_sgs returned failure\n"); 299 return -EIO; 300 } 301 } 302 virtqueue_kick(chan->vq); 303 spin_unlock_irqrestore(&chan->lock, flags); 304 305 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 306 return 0; 307 } 308 309 static int p9_get_mapped_pages(struct virtio_chan *chan, 310 struct page ***pages, 311 struct iov_iter *data, 312 int count, 313 size_t *offs, 314 int *need_drop) 315 { 316 int nr_pages; 317 int err; 318 319 if (!iov_iter_count(data)) 320 return 0; 321 322 if (!iov_iter_is_kvec(data)) { 323 int n; 324 /* 325 * We allow only p9_max_pages pinned. We wait for the 326 * Other zc request to finish here 327 */ 328 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) { 329 err = wait_event_killable(vp_wq, 330 (atomic_read(&vp_pinned) < chan->p9_max_pages)); 331 if (err == -ERESTARTSYS) 332 return err; 333 } 334 n = iov_iter_get_pages_alloc(data, pages, count, offs); 335 if (n < 0) 336 return n; 337 *need_drop = 1; 338 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE); 339 atomic_add(nr_pages, &vp_pinned); 340 return n; 341 } else { 342 /* kernel buffer, no need to pin pages */ 343 int index; 344 size_t len; 345 void *p; 346 347 /* we'd already checked that it's non-empty */ 348 while (1) { 349 len = iov_iter_single_seg_count(data); 350 if (likely(len)) { 351 p = data->kvec->iov_base + data->iov_offset; 352 break; 353 } 354 iov_iter_advance(data, 0); 355 } 356 if (len > count) 357 len = count; 358 359 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) - 360 (unsigned long)p / PAGE_SIZE; 361 362 *pages = kmalloc_array(nr_pages, sizeof(struct page *), 363 GFP_NOFS); 364 if (!*pages) 365 return -ENOMEM; 366 367 *need_drop = 0; 368 p -= (*offs = offset_in_page(p)); 369 for (index = 0; index < nr_pages; index++) { 370 if (is_vmalloc_addr(p)) 371 (*pages)[index] = vmalloc_to_page(p); 372 else 373 (*pages)[index] = kmap_to_page(p); 374 p += PAGE_SIZE; 375 } 376 return len; 377 } 378 } 379 380 /** 381 * p9_virtio_zc_request - issue a zero copy request 382 * @client: client instance issuing the request 383 * @req: request to be issued 384 * @uidata: user buffer that should be used for zero copy read 385 * @uodata: user buffer that should be used for zero copy write 386 * @inlen: read buffer size 387 * @outlen: write buffer size 388 * @in_hdr_len: reader header size, This is the size of response protocol data 389 * 390 */ 391 static int 392 p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req, 393 struct iov_iter *uidata, struct iov_iter *uodata, 394 int inlen, int outlen, int in_hdr_len) 395 { 396 int in, out, err, out_sgs, in_sgs; 397 unsigned long flags; 398 int in_nr_pages = 0, out_nr_pages = 0; 399 struct page **in_pages = NULL, **out_pages = NULL; 400 struct virtio_chan *chan = client->trans; 401 struct scatterlist *sgs[4]; 402 size_t offs; 403 int need_drop = 0; 404 int kicked = 0; 405 406 p9_debug(P9_DEBUG_TRANS, "virtio request\n"); 407 408 if (uodata) { 409 __le32 sz; 410 int n = p9_get_mapped_pages(chan, &out_pages, uodata, 411 outlen, &offs, &need_drop); 412 if (n < 0) { 413 err = n; 414 goto err_out; 415 } 416 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); 417 if (n != outlen) { 418 __le32 v = cpu_to_le32(n); 419 memcpy(&req->tc.sdata[req->tc.size - 4], &v, 4); 420 outlen = n; 421 } 422 /* The size field of the message must include the length of the 423 * header and the length of the data. We didn't actually know 424 * the length of the data until this point so add it in now. 425 */ 426 sz = cpu_to_le32(req->tc.size + outlen); 427 memcpy(&req->tc.sdata[0], &sz, sizeof(sz)); 428 } else if (uidata) { 429 int n = p9_get_mapped_pages(chan, &in_pages, uidata, 430 inlen, &offs, &need_drop); 431 if (n < 0) { 432 err = n; 433 goto err_out; 434 } 435 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); 436 if (n != inlen) { 437 __le32 v = cpu_to_le32(n); 438 memcpy(&req->tc.sdata[req->tc.size - 4], &v, 4); 439 inlen = n; 440 } 441 } 442 req->status = REQ_STATUS_SENT; 443 req_retry_pinned: 444 spin_lock_irqsave(&chan->lock, flags); 445 446 out_sgs = in_sgs = 0; 447 448 /* out data */ 449 out = pack_sg_list(chan->sg, 0, 450 VIRTQUEUE_NUM, req->tc.sdata, req->tc.size); 451 452 if (out) 453 sgs[out_sgs++] = chan->sg; 454 455 if (out_pages) { 456 sgs[out_sgs++] = chan->sg + out; 457 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM, 458 out_pages, out_nr_pages, offs, outlen); 459 } 460 461 /* 462 * Take care of in data 463 * For example TREAD have 11. 464 * 11 is the read/write header = PDU Header(7) + IO Size (4). 465 * Arrange in such a way that server places header in the 466 * allocated memory and payload onto the user buffer. 467 */ 468 in = pack_sg_list(chan->sg, out, 469 VIRTQUEUE_NUM, req->rc.sdata, in_hdr_len); 470 if (in) 471 sgs[out_sgs + in_sgs++] = chan->sg + out; 472 473 if (in_pages) { 474 sgs[out_sgs + in_sgs++] = chan->sg + out + in; 475 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM, 476 in_pages, in_nr_pages, offs, inlen); 477 } 478 479 BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs)); 480 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req, 481 GFP_ATOMIC); 482 if (err < 0) { 483 if (err == -ENOSPC) { 484 chan->ring_bufs_avail = 0; 485 spin_unlock_irqrestore(&chan->lock, flags); 486 err = wait_event_killable(*chan->vc_wq, 487 chan->ring_bufs_avail); 488 if (err == -ERESTARTSYS) 489 goto err_out; 490 491 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 492 goto req_retry_pinned; 493 } else { 494 spin_unlock_irqrestore(&chan->lock, flags); 495 p9_debug(P9_DEBUG_TRANS, 496 "virtio rpc add_sgs returned failure\n"); 497 err = -EIO; 498 goto err_out; 499 } 500 } 501 virtqueue_kick(chan->vq); 502 spin_unlock_irqrestore(&chan->lock, flags); 503 kicked = 1; 504 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 505 err = wait_event_killable(req->wq, req->status >= REQ_STATUS_RCVD); 506 /* 507 * Non kernel buffers are pinned, unpin them 508 */ 509 err_out: 510 if (need_drop) { 511 if (in_pages) { 512 p9_release_pages(in_pages, in_nr_pages); 513 atomic_sub(in_nr_pages, &vp_pinned); 514 } 515 if (out_pages) { 516 p9_release_pages(out_pages, out_nr_pages); 517 atomic_sub(out_nr_pages, &vp_pinned); 518 } 519 /* wakeup anybody waiting for slots to pin pages */ 520 wake_up(&vp_wq); 521 } 522 kvfree(in_pages); 523 kvfree(out_pages); 524 if (!kicked) { 525 /* reply won't come */ 526 p9_req_put(req); 527 } 528 return err; 529 } 530 531 static ssize_t p9_mount_tag_show(struct device *dev, 532 struct device_attribute *attr, char *buf) 533 { 534 struct virtio_chan *chan; 535 struct virtio_device *vdev; 536 int tag_len; 537 538 vdev = dev_to_virtio(dev); 539 chan = vdev->priv; 540 tag_len = strlen(chan->tag); 541 542 memcpy(buf, chan->tag, tag_len + 1); 543 544 return tag_len + 1; 545 } 546 547 static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL); 548 549 /** 550 * p9_virtio_probe - probe for existence of 9P virtio channels 551 * @vdev: virtio device to probe 552 * 553 * This probes for existing virtio channels. 554 * 555 */ 556 557 static int p9_virtio_probe(struct virtio_device *vdev) 558 { 559 __u16 tag_len; 560 char *tag; 561 int err; 562 struct virtio_chan *chan; 563 564 if (!vdev->config->get) { 565 dev_err(&vdev->dev, "%s failure: config access disabled\n", 566 __func__); 567 return -EINVAL; 568 } 569 570 chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL); 571 if (!chan) { 572 pr_err("Failed to allocate virtio 9P channel\n"); 573 err = -ENOMEM; 574 goto fail; 575 } 576 577 chan->vdev = vdev; 578 579 /* We expect one virtqueue, for requests. */ 580 chan->vq = virtio_find_single_vq(vdev, req_done, "requests"); 581 if (IS_ERR(chan->vq)) { 582 err = PTR_ERR(chan->vq); 583 goto out_free_chan; 584 } 585 chan->vq->vdev->priv = chan; 586 spin_lock_init(&chan->lock); 587 588 sg_init_table(chan->sg, VIRTQUEUE_NUM); 589 590 chan->inuse = false; 591 if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) { 592 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len); 593 } else { 594 err = -EINVAL; 595 goto out_free_vq; 596 } 597 tag = kzalloc(tag_len + 1, GFP_KERNEL); 598 if (!tag) { 599 err = -ENOMEM; 600 goto out_free_vq; 601 } 602 603 virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag), 604 tag, tag_len); 605 chan->tag = tag; 606 err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 607 if (err) { 608 goto out_free_tag; 609 } 610 chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL); 611 if (!chan->vc_wq) { 612 err = -ENOMEM; 613 goto out_free_tag; 614 } 615 init_waitqueue_head(chan->vc_wq); 616 chan->ring_bufs_avail = 1; 617 /* Ceiling limit to avoid denial of service attacks */ 618 chan->p9_max_pages = nr_free_buffer_pages()/4; 619 620 virtio_device_ready(vdev); 621 622 mutex_lock(&virtio_9p_lock); 623 list_add_tail(&chan->chan_list, &virtio_chan_list); 624 mutex_unlock(&virtio_9p_lock); 625 626 /* Let udev rules use the new mount_tag attribute. */ 627 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); 628 629 return 0; 630 631 out_free_tag: 632 kfree(tag); 633 out_free_vq: 634 vdev->config->del_vqs(vdev); 635 out_free_chan: 636 kfree(chan); 637 fail: 638 return err; 639 } 640 641 642 /** 643 * p9_virtio_create - allocate a new virtio channel 644 * @client: client instance invoking this transport 645 * @devname: string identifying the channel to connect to (unused) 646 * @args: args passed from sys_mount() for per-transport options (unused) 647 * 648 * This sets up a transport channel for 9p communication. Right now 649 * we only match the first available channel, but eventually we couldlook up 650 * alternate channels by matching devname versus a virtio_config entry. 651 * We use a simple reference count mechanism to ensure that only a single 652 * mount has a channel open at a time. 653 * 654 */ 655 656 static int 657 p9_virtio_create(struct p9_client *client, const char *devname, char *args) 658 { 659 struct virtio_chan *chan; 660 int ret = -ENOENT; 661 int found = 0; 662 663 if (devname == NULL) 664 return -EINVAL; 665 666 mutex_lock(&virtio_9p_lock); 667 list_for_each_entry(chan, &virtio_chan_list, chan_list) { 668 if (!strcmp(devname, chan->tag)) { 669 if (!chan->inuse) { 670 chan->inuse = true; 671 found = 1; 672 break; 673 } 674 ret = -EBUSY; 675 } 676 } 677 mutex_unlock(&virtio_9p_lock); 678 679 if (!found) { 680 pr_err("no channels available for device %s\n", devname); 681 return ret; 682 } 683 684 client->trans = (void *)chan; 685 client->status = Connected; 686 chan->client = client; 687 688 return 0; 689 } 690 691 /** 692 * p9_virtio_remove - clean up resources associated with a virtio device 693 * @vdev: virtio device to remove 694 * 695 */ 696 697 static void p9_virtio_remove(struct virtio_device *vdev) 698 { 699 struct virtio_chan *chan = vdev->priv; 700 unsigned long warning_time; 701 702 mutex_lock(&virtio_9p_lock); 703 704 /* Remove self from list so we don't get new users. */ 705 list_del(&chan->chan_list); 706 warning_time = jiffies; 707 708 /* Wait for existing users to close. */ 709 while (chan->inuse) { 710 mutex_unlock(&virtio_9p_lock); 711 msleep(250); 712 if (time_after(jiffies, warning_time + 10 * HZ)) { 713 dev_emerg(&vdev->dev, 714 "p9_virtio_remove: waiting for device in use.\n"); 715 warning_time = jiffies; 716 } 717 mutex_lock(&virtio_9p_lock); 718 } 719 720 mutex_unlock(&virtio_9p_lock); 721 722 vdev->config->reset(vdev); 723 vdev->config->del_vqs(vdev); 724 725 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 726 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); 727 kfree(chan->tag); 728 kfree(chan->vc_wq); 729 kfree(chan); 730 731 } 732 733 static struct virtio_device_id id_table[] = { 734 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID }, 735 { 0 }, 736 }; 737 738 static unsigned int features[] = { 739 VIRTIO_9P_MOUNT_TAG, 740 }; 741 742 /* The standard "struct lguest_driver": */ 743 static struct virtio_driver p9_virtio_drv = { 744 .feature_table = features, 745 .feature_table_size = ARRAY_SIZE(features), 746 .driver.name = KBUILD_MODNAME, 747 .driver.owner = THIS_MODULE, 748 .id_table = id_table, 749 .probe = p9_virtio_probe, 750 .remove = p9_virtio_remove, 751 }; 752 753 static struct p9_trans_module p9_virtio_trans = { 754 .name = "virtio", 755 .create = p9_virtio_create, 756 .close = p9_virtio_close, 757 .request = p9_virtio_request, 758 .zc_request = p9_virtio_zc_request, 759 .cancel = p9_virtio_cancel, 760 .cancelled = p9_virtio_cancelled, 761 /* 762 * We leave one entry for input and one entry for response 763 * headers. We also skip one more entry to accommodate, address 764 * that are not at page boundary, that can result in an extra 765 * page in zero copy. 766 */ 767 .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3), 768 .def = 1, 769 .owner = THIS_MODULE, 770 }; 771 772 /* The standard init function */ 773 static int __init p9_virtio_init(void) 774 { 775 int rc; 776 777 INIT_LIST_HEAD(&virtio_chan_list); 778 779 v9fs_register_trans(&p9_virtio_trans); 780 rc = register_virtio_driver(&p9_virtio_drv); 781 if (rc) 782 v9fs_unregister_trans(&p9_virtio_trans); 783 784 return rc; 785 } 786 787 static void __exit p9_virtio_cleanup(void) 788 { 789 unregister_virtio_driver(&p9_virtio_drv); 790 v9fs_unregister_trans(&p9_virtio_trans); 791 } 792 793 module_init(p9_virtio_init); 794 module_exit(p9_virtio_cleanup); 795 796 MODULE_DEVICE_TABLE(virtio, id_table); 797 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>"); 798 MODULE_DESCRIPTION("Virtio 9p Transport"); 799 MODULE_LICENSE("GPL"); 800