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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 */
42static DEFINE_MUTEX(virtio_9p_lock);
43static DECLARE_WAIT_QUEUE_HEAD(vp_wq);
44static 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
65struct 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
89static struct list_head virtio_chan_list;
90
91/* How many bytes left in this page. */
92static 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
106static 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
129static 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
171static 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 */
194static 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 */
200static 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 */
217static int
218pack_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
255static int
256p9_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;
267req_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
309static 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 */
391static int
392p9_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;
443req_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 */
509err_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
531static 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
547static 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
557static 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_remove_file;
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
631out_remove_file:
632 sysfs_remove_file(&vdev->dev.kobj, &dev_attr_mount_tag.attr);
633out_free_tag:
634 kfree(tag);
635out_free_vq:
636 vdev->config->del_vqs(vdev);
637out_free_chan:
638 kfree(chan);
639fail:
640 return err;
641}
642
643
644/**
645 * p9_virtio_create - allocate a new virtio channel
646 * @client: client instance invoking this transport
647 * @devname: string identifying the channel to connect to (unused)
648 * @args: args passed from sys_mount() for per-transport options (unused)
649 *
650 * This sets up a transport channel for 9p communication. Right now
651 * we only match the first available channel, but eventually we couldlook up
652 * alternate channels by matching devname versus a virtio_config entry.
653 * We use a simple reference count mechanism to ensure that only a single
654 * mount has a channel open at a time.
655 *
656 */
657
658static int
659p9_virtio_create(struct p9_client *client, const char *devname, char *args)
660{
661 struct virtio_chan *chan;
662 int ret = -ENOENT;
663 int found = 0;
664
665 if (devname == NULL)
666 return -EINVAL;
667
668 mutex_lock(&virtio_9p_lock);
669 list_for_each_entry(chan, &virtio_chan_list, chan_list) {
670 if (!strcmp(devname, chan->tag)) {
671 if (!chan->inuse) {
672 chan->inuse = true;
673 found = 1;
674 break;
675 }
676 ret = -EBUSY;
677 }
678 }
679 mutex_unlock(&virtio_9p_lock);
680
681 if (!found) {
682 pr_err("no channels available for device %s\n", devname);
683 return ret;
684 }
685
686 client->trans = (void *)chan;
687 client->status = Connected;
688 chan->client = client;
689
690 return 0;
691}
692
693/**
694 * p9_virtio_remove - clean up resources associated with a virtio device
695 * @vdev: virtio device to remove
696 *
697 */
698
699static void p9_virtio_remove(struct virtio_device *vdev)
700{
701 struct virtio_chan *chan = vdev->priv;
702 unsigned long warning_time;
703
704 mutex_lock(&virtio_9p_lock);
705
706 /* Remove self from list so we don't get new users. */
707 list_del(&chan->chan_list);
708 warning_time = jiffies;
709
710 /* Wait for existing users to close. */
711 while (chan->inuse) {
712 mutex_unlock(&virtio_9p_lock);
713 msleep(250);
714 if (time_after(jiffies, warning_time + 10 * HZ)) {
715 dev_emerg(&vdev->dev,
716 "p9_virtio_remove: waiting for device in use.\n");
717 warning_time = jiffies;
718 }
719 mutex_lock(&virtio_9p_lock);
720 }
721
722 mutex_unlock(&virtio_9p_lock);
723
724 vdev->config->reset(vdev);
725 vdev->config->del_vqs(vdev);
726
727 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
728 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
729 kfree(chan->tag);
730 kfree(chan->vc_wq);
731 kfree(chan);
732
733}
734
735static struct virtio_device_id id_table[] = {
736 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
737 { 0 },
738};
739
740static unsigned int features[] = {
741 VIRTIO_9P_MOUNT_TAG,
742};
743
744/* The standard "struct lguest_driver": */
745static struct virtio_driver p9_virtio_drv = {
746 .feature_table = features,
747 .feature_table_size = ARRAY_SIZE(features),
748 .driver.name = KBUILD_MODNAME,
749 .driver.owner = THIS_MODULE,
750 .id_table = id_table,
751 .probe = p9_virtio_probe,
752 .remove = p9_virtio_remove,
753};
754
755static struct p9_trans_module p9_virtio_trans = {
756 .name = "virtio",
757 .create = p9_virtio_create,
758 .close = p9_virtio_close,
759 .request = p9_virtio_request,
760 .zc_request = p9_virtio_zc_request,
761 .cancel = p9_virtio_cancel,
762 .cancelled = p9_virtio_cancelled,
763 /*
764 * We leave one entry for input and one entry for response
765 * headers. We also skip one more entry to accommodate, address
766 * that are not at page boundary, that can result in an extra
767 * page in zero copy.
768 */
769 .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),
770 .def = 1,
771 .owner = THIS_MODULE,
772};
773
774/* The standard init function */
775static int __init p9_virtio_init(void)
776{
777 int rc;
778
779 INIT_LIST_HEAD(&virtio_chan_list);
780
781 v9fs_register_trans(&p9_virtio_trans);
782 rc = register_virtio_driver(&p9_virtio_drv);
783 if (rc)
784 v9fs_unregister_trans(&p9_virtio_trans);
785
786 return rc;
787}
788
789static void __exit p9_virtio_cleanup(void)
790{
791 unregister_virtio_driver(&p9_virtio_drv);
792 v9fs_unregister_trans(&p9_virtio_trans);
793}
794
795module_init(p9_virtio_init);
796module_exit(p9_virtio_cleanup);
797
798MODULE_DEVICE_TABLE(virtio, id_table);
799MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
800MODULE_DESCRIPTION("Virtio 9p Transport");
801MODULE_LICENSE("GPL");
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 */
57static DEFINE_MUTEX(virtio_9p_lock);
58static DECLARE_WAIT_QUEUE_HEAD(vp_wq);
59static 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
77struct 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
103static struct list_head virtio_chan_list;
104
105/* How many bytes left in this page. */
106static unsigned int rest_of_page(void *data)
107{
108 return PAGE_SIZE - offset_in_page(data);
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
120static 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
143static void req_done(struct virtqueue *vq)
144{
145 struct virtio_chan *chan = vq->vdev->priv;
146 unsigned int len;
147 struct p9_req_t *req;
148 unsigned long flags;
149
150 p9_debug(P9_DEBUG_TRANS, ": request done\n");
151
152 while (1) {
153 spin_lock_irqsave(&chan->lock, flags);
154 req = virtqueue_get_buf(chan->vq, &len);
155 if (req == NULL) {
156 spin_unlock_irqrestore(&chan->lock, flags);
157 break;
158 }
159 chan->ring_bufs_avail = 1;
160 spin_unlock_irqrestore(&chan->lock, flags);
161 /* Wakeup if anyone waiting for VirtIO ring space. */
162 wake_up(chan->vc_wq);
163 p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
164 }
165}
166
167/**
168 * pack_sg_list - pack a scatter gather list from a linear buffer
169 * @sg: scatter/gather list to pack into
170 * @start: which segment of the sg_list to start at
171 * @limit: maximum segment to pack data to
172 * @data: data to pack into scatter/gather list
173 * @count: amount of data to pack into the scatter/gather list
174 *
175 * sg_lists have multiple segments of various sizes. This will pack
176 * arbitrary data into an existing scatter gather list, segmenting the
177 * data as necessary within constraints.
178 *
179 */
180
181static int pack_sg_list(struct scatterlist *sg, int start,
182 int limit, char *data, int count)
183{
184 int s;
185 int index = start;
186
187 while (count) {
188 s = rest_of_page(data);
189 if (s > count)
190 s = count;
191 BUG_ON(index > limit);
192 /* Make sure we don't terminate early. */
193 sg_unmark_end(&sg[index]);
194 sg_set_buf(&sg[index++], data, s);
195 count -= s;
196 data += s;
197 }
198 if (index-start)
199 sg_mark_end(&sg[index - 1]);
200 return index-start;
201}
202
203/* We don't currently allow canceling of virtio requests */
204static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
205{
206 return 1;
207}
208
209/**
210 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
211 * this takes a list of pages.
212 * @sg: scatter/gather list to pack into
213 * @start: which segment of the sg_list to start at
214 * @pdata: a list of pages to add into sg.
215 * @nr_pages: number of pages to pack into the scatter/gather list
216 * @offs: amount of data in the beginning of first page _not_ to pack
217 * @count: amount of data to pack into the scatter/gather list
218 */
219static int
220pack_sg_list_p(struct scatterlist *sg, int start, int limit,
221 struct page **pdata, int nr_pages, size_t offs, int count)
222{
223 int i = 0, s;
224 int data_off = offs;
225 int index = start;
226
227 BUG_ON(nr_pages > (limit - start));
228 /*
229 * if the first page doesn't start at
230 * page boundary find the offset
231 */
232 while (nr_pages) {
233 s = PAGE_SIZE - data_off;
234 if (s > count)
235 s = count;
236 /* Make sure we don't terminate early. */
237 sg_unmark_end(&sg[index]);
238 sg_set_page(&sg[index++], pdata[i++], s, data_off);
239 data_off = 0;
240 count -= s;
241 nr_pages--;
242 }
243
244 if (index-start)
245 sg_mark_end(&sg[index - 1]);
246 return index - start;
247}
248
249/**
250 * p9_virtio_request - issue a request
251 * @client: client instance issuing the request
252 * @req: request to be issued
253 *
254 */
255
256static int
257p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
258{
259 int err;
260 int in, out, out_sgs, in_sgs;
261 unsigned long flags;
262 struct virtio_chan *chan = client->trans;
263 struct scatterlist *sgs[2];
264
265 p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n");
266
267 req->status = REQ_STATUS_SENT;
268req_retry:
269 spin_lock_irqsave(&chan->lock, flags);
270
271 out_sgs = in_sgs = 0;
272 /* Handle out VirtIO ring buffers */
273 out = pack_sg_list(chan->sg, 0,
274 VIRTQUEUE_NUM, req->tc->sdata, req->tc->size);
275 if (out)
276 sgs[out_sgs++] = chan->sg;
277
278 in = pack_sg_list(chan->sg, out,
279 VIRTQUEUE_NUM, req->rc->sdata, req->rc->capacity);
280 if (in)
281 sgs[out_sgs + in_sgs++] = chan->sg + out;
282
283 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req,
284 GFP_ATOMIC);
285 if (err < 0) {
286 if (err == -ENOSPC) {
287 chan->ring_bufs_avail = 0;
288 spin_unlock_irqrestore(&chan->lock, flags);
289 err = wait_event_interruptible(*chan->vc_wq,
290 chan->ring_bufs_avail);
291 if (err == -ERESTARTSYS)
292 return err;
293
294 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
295 goto req_retry;
296 } else {
297 spin_unlock_irqrestore(&chan->lock, flags);
298 p9_debug(P9_DEBUG_TRANS,
299 "virtio rpc add_sgs returned failure\n");
300 return -EIO;
301 }
302 }
303 virtqueue_kick(chan->vq);
304 spin_unlock_irqrestore(&chan->lock, flags);
305
306 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
307 return 0;
308}
309
310static int p9_get_mapped_pages(struct virtio_chan *chan,
311 struct page ***pages,
312 struct iov_iter *data,
313 int count,
314 size_t *offs,
315 int *need_drop)
316{
317 int nr_pages;
318 int err;
319
320 if (!iov_iter_count(data))
321 return 0;
322
323 if (!(data->type & ITER_KVEC)) {
324 int n;
325 /*
326 * We allow only p9_max_pages pinned. We wait for the
327 * Other zc request to finish here
328 */
329 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
330 err = wait_event_interruptible(vp_wq,
331 (atomic_read(&vp_pinned) < chan->p9_max_pages));
332 if (err == -ERESTARTSYS)
333 return err;
334 }
335 n = iov_iter_get_pages_alloc(data, pages, count, offs);
336 if (n < 0)
337 return n;
338 *need_drop = 1;
339 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE);
340 atomic_add(nr_pages, &vp_pinned);
341 return n;
342 } else {
343 /* kernel buffer, no need to pin pages */
344 int index;
345 size_t len;
346 void *p;
347
348 /* we'd already checked that it's non-empty */
349 while (1) {
350 len = iov_iter_single_seg_count(data);
351 if (likely(len)) {
352 p = data->kvec->iov_base + data->iov_offset;
353 break;
354 }
355 iov_iter_advance(data, 0);
356 }
357 if (len > count)
358 len = count;
359
360 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) -
361 (unsigned long)p / PAGE_SIZE;
362
363 *pages = kmalloc(sizeof(struct page *) * nr_pages, 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 bffer that should be ued for zero copy read
385 * @uodata: user buffer that shoud be user for zero copy write
386 * @inlen: read buffer size
387 * @olen: write buffer size
388 * @hdrlen: reader header size, This is the size of response protocol data
389 *
390 */
391static int
392p9_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
405 p9_debug(P9_DEBUG_TRANS, "virtio request\n");
406
407 if (uodata) {
408 int n = p9_get_mapped_pages(chan, &out_pages, uodata,
409 outlen, &offs, &need_drop);
410 if (n < 0)
411 return n;
412 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
413 if (n != outlen) {
414 __le32 v = cpu_to_le32(n);
415 memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4);
416 outlen = n;
417 }
418 } else if (uidata) {
419 int n = p9_get_mapped_pages(chan, &in_pages, uidata,
420 inlen, &offs, &need_drop);
421 if (n < 0)
422 return n;
423 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
424 if (n != inlen) {
425 __le32 v = cpu_to_le32(n);
426 memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4);
427 inlen = n;
428 }
429 }
430 req->status = REQ_STATUS_SENT;
431req_retry_pinned:
432 spin_lock_irqsave(&chan->lock, flags);
433
434 out_sgs = in_sgs = 0;
435
436 /* out data */
437 out = pack_sg_list(chan->sg, 0,
438 VIRTQUEUE_NUM, req->tc->sdata, req->tc->size);
439
440 if (out)
441 sgs[out_sgs++] = chan->sg;
442
443 if (out_pages) {
444 sgs[out_sgs++] = chan->sg + out;
445 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
446 out_pages, out_nr_pages, offs, outlen);
447 }
448
449 /*
450 * Take care of in data
451 * For example TREAD have 11.
452 * 11 is the read/write header = PDU Header(7) + IO Size (4).
453 * Arrange in such a way that server places header in the
454 * alloced memory and payload onto the user buffer.
455 */
456 in = pack_sg_list(chan->sg, out,
457 VIRTQUEUE_NUM, req->rc->sdata, in_hdr_len);
458 if (in)
459 sgs[out_sgs + in_sgs++] = chan->sg + out;
460
461 if (in_pages) {
462 sgs[out_sgs + in_sgs++] = chan->sg + out + in;
463 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
464 in_pages, in_nr_pages, offs, inlen);
465 }
466
467 BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs));
468 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req,
469 GFP_ATOMIC);
470 if (err < 0) {
471 if (err == -ENOSPC) {
472 chan->ring_bufs_avail = 0;
473 spin_unlock_irqrestore(&chan->lock, flags);
474 err = wait_event_interruptible(*chan->vc_wq,
475 chan->ring_bufs_avail);
476 if (err == -ERESTARTSYS)
477 goto err_out;
478
479 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
480 goto req_retry_pinned;
481 } else {
482 spin_unlock_irqrestore(&chan->lock, flags);
483 p9_debug(P9_DEBUG_TRANS,
484 "virtio rpc add_sgs returned failure\n");
485 err = -EIO;
486 goto err_out;
487 }
488 }
489 virtqueue_kick(chan->vq);
490 spin_unlock_irqrestore(&chan->lock, flags);
491 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
492 err = wait_event_interruptible(*req->wq,
493 req->status >= REQ_STATUS_RCVD);
494 /*
495 * Non kernel buffers are pinned, unpin them
496 */
497err_out:
498 if (need_drop) {
499 if (in_pages) {
500 p9_release_pages(in_pages, in_nr_pages);
501 atomic_sub(in_nr_pages, &vp_pinned);
502 }
503 if (out_pages) {
504 p9_release_pages(out_pages, out_nr_pages);
505 atomic_sub(out_nr_pages, &vp_pinned);
506 }
507 /* wakeup anybody waiting for slots to pin pages */
508 wake_up(&vp_wq);
509 }
510 kfree(in_pages);
511 kfree(out_pages);
512 return err;
513}
514
515static ssize_t p9_mount_tag_show(struct device *dev,
516 struct device_attribute *attr, char *buf)
517{
518 struct virtio_chan *chan;
519 struct virtio_device *vdev;
520
521 vdev = dev_to_virtio(dev);
522 chan = vdev->priv;
523
524 memcpy(buf, chan->tag, chan->tag_len);
525 buf[chan->tag_len] = 0;
526
527 return chan->tag_len + 1;
528}
529
530static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
531
532/**
533 * p9_virtio_probe - probe for existence of 9P virtio channels
534 * @vdev: virtio device to probe
535 *
536 * This probes for existing virtio channels.
537 *
538 */
539
540static int p9_virtio_probe(struct virtio_device *vdev)
541{
542 __u16 tag_len;
543 char *tag;
544 int err;
545 struct virtio_chan *chan;
546
547 if (!vdev->config->get) {
548 dev_err(&vdev->dev, "%s failure: config access disabled\n",
549 __func__);
550 return -EINVAL;
551 }
552
553 chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
554 if (!chan) {
555 pr_err("Failed to allocate virtio 9P channel\n");
556 err = -ENOMEM;
557 goto fail;
558 }
559
560 chan->vdev = vdev;
561
562 /* We expect one virtqueue, for requests. */
563 chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
564 if (IS_ERR(chan->vq)) {
565 err = PTR_ERR(chan->vq);
566 goto out_free_vq;
567 }
568 chan->vq->vdev->priv = chan;
569 spin_lock_init(&chan->lock);
570
571 sg_init_table(chan->sg, VIRTQUEUE_NUM);
572
573 chan->inuse = false;
574 if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) {
575 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len);
576 } else {
577 err = -EINVAL;
578 goto out_free_vq;
579 }
580 tag = kmalloc(tag_len, GFP_KERNEL);
581 if (!tag) {
582 err = -ENOMEM;
583 goto out_free_vq;
584 }
585
586 virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag),
587 tag, tag_len);
588 chan->tag = tag;
589 chan->tag_len = tag_len;
590 err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
591 if (err) {
592 goto out_free_tag;
593 }
594 chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
595 if (!chan->vc_wq) {
596 err = -ENOMEM;
597 goto out_free_tag;
598 }
599 init_waitqueue_head(chan->vc_wq);
600 chan->ring_bufs_avail = 1;
601 /* Ceiling limit to avoid denial of service attacks */
602 chan->p9_max_pages = nr_free_buffer_pages()/4;
603
604 virtio_device_ready(vdev);
605
606 mutex_lock(&virtio_9p_lock);
607 list_add_tail(&chan->chan_list, &virtio_chan_list);
608 mutex_unlock(&virtio_9p_lock);
609
610 /* Let udev rules use the new mount_tag attribute. */
611 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
612
613 return 0;
614
615out_free_tag:
616 kfree(tag);
617out_free_vq:
618 vdev->config->del_vqs(vdev);
619 kfree(chan);
620fail:
621 return err;
622}
623
624
625/**
626 * p9_virtio_create - allocate a new virtio channel
627 * @client: client instance invoking this transport
628 * @devname: string identifying the channel to connect to (unused)
629 * @args: args passed from sys_mount() for per-transport options (unused)
630 *
631 * This sets up a transport channel for 9p communication. Right now
632 * we only match the first available channel, but eventually we couldlook up
633 * alternate channels by matching devname versus a virtio_config entry.
634 * We use a simple reference count mechanism to ensure that only a single
635 * mount has a channel open at a time.
636 *
637 */
638
639static int
640p9_virtio_create(struct p9_client *client, const char *devname, char *args)
641{
642 struct virtio_chan *chan;
643 int ret = -ENOENT;
644 int found = 0;
645
646 mutex_lock(&virtio_9p_lock);
647 list_for_each_entry(chan, &virtio_chan_list, chan_list) {
648 if (!strncmp(devname, chan->tag, chan->tag_len) &&
649 strlen(devname) == chan->tag_len) {
650 if (!chan->inuse) {
651 chan->inuse = true;
652 found = 1;
653 break;
654 }
655 ret = -EBUSY;
656 }
657 }
658 mutex_unlock(&virtio_9p_lock);
659
660 if (!found) {
661 pr_err("no channels available for device %s\n", devname);
662 return ret;
663 }
664
665 client->trans = (void *)chan;
666 client->status = Connected;
667 chan->client = client;
668
669 return 0;
670}
671
672/**
673 * p9_virtio_remove - clean up resources associated with a virtio device
674 * @vdev: virtio device to remove
675 *
676 */
677
678static void p9_virtio_remove(struct virtio_device *vdev)
679{
680 struct virtio_chan *chan = vdev->priv;
681 unsigned long warning_time;
682
683 mutex_lock(&virtio_9p_lock);
684
685 /* Remove self from list so we don't get new users. */
686 list_del(&chan->chan_list);
687 warning_time = jiffies;
688
689 /* Wait for existing users to close. */
690 while (chan->inuse) {
691 mutex_unlock(&virtio_9p_lock);
692 msleep(250);
693 if (time_after(jiffies, warning_time + 10 * HZ)) {
694 dev_emerg(&vdev->dev,
695 "p9_virtio_remove: waiting for device in use.\n");
696 warning_time = jiffies;
697 }
698 mutex_lock(&virtio_9p_lock);
699 }
700
701 mutex_unlock(&virtio_9p_lock);
702
703 vdev->config->reset(vdev);
704 vdev->config->del_vqs(vdev);
705
706 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
707 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
708 kfree(chan->tag);
709 kfree(chan->vc_wq);
710 kfree(chan);
711
712}
713
714static struct virtio_device_id id_table[] = {
715 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
716 { 0 },
717};
718
719static unsigned int features[] = {
720 VIRTIO_9P_MOUNT_TAG,
721};
722
723/* The standard "struct lguest_driver": */
724static struct virtio_driver p9_virtio_drv = {
725 .feature_table = features,
726 .feature_table_size = ARRAY_SIZE(features),
727 .driver.name = KBUILD_MODNAME,
728 .driver.owner = THIS_MODULE,
729 .id_table = id_table,
730 .probe = p9_virtio_probe,
731 .remove = p9_virtio_remove,
732};
733
734static struct p9_trans_module p9_virtio_trans = {
735 .name = "virtio",
736 .create = p9_virtio_create,
737 .close = p9_virtio_close,
738 .request = p9_virtio_request,
739 .zc_request = p9_virtio_zc_request,
740 .cancel = p9_virtio_cancel,
741 /*
742 * We leave one entry for input and one entry for response
743 * headers. We also skip one more entry to accomodate, address
744 * that are not at page boundary, that can result in an extra
745 * page in zero copy.
746 */
747 .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),
748 .def = 1,
749 .owner = THIS_MODULE,
750};
751
752/* The standard init function */
753static int __init p9_virtio_init(void)
754{
755 INIT_LIST_HEAD(&virtio_chan_list);
756
757 v9fs_register_trans(&p9_virtio_trans);
758 return register_virtio_driver(&p9_virtio_drv);
759}
760
761static void __exit p9_virtio_cleanup(void)
762{
763 unregister_virtio_driver(&p9_virtio_drv);
764 v9fs_unregister_trans(&p9_virtio_trans);
765}
766
767module_init(p9_virtio_init);
768module_exit(p9_virtio_cleanup);
769
770MODULE_DEVICE_TABLE(virtio, id_table);
771MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
772MODULE_DESCRIPTION("Virtio 9p Transport");
773MODULE_LICENSE("GPL");