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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
57static DEFINE_MUTEX(virtio_9p_lock);
58static DECLARE_WAIT_QUEUE_HEAD(vp_wq);
59static atomic_t vp_pinned = ATOMIC_INIT(0);
60
61
62
63
64
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74
75
76struct virtio_chan {
77 bool inuse;
78
79 spinlock_t lock;
80
81 struct p9_client *client;
82 struct virtio_device *vdev;
83 struct virtqueue *vq;
84 int ring_bufs_avail;
85 wait_queue_head_t *vc_wq;
86
87
88
89 unsigned long p9_max_pages;
90
91 struct scatterlist sg[VIRTQUEUE_NUM];
92
93 int tag_len;
94
95
96
97 char *tag;
98
99 struct list_head chan_list;
100};
101
102static struct list_head virtio_chan_list;
103
104
105static unsigned int rest_of_page(void *data)
106{
107 return PAGE_SIZE - offset_in_page(data);
108}
109
110
111
112
113
114
115
116
117
118
119static void p9_virtio_close(struct p9_client *client)
120{
121 struct virtio_chan *chan = client->trans;
122
123 mutex_lock(&virtio_9p_lock);
124 if (chan)
125 chan->inuse = false;
126 mutex_unlock(&virtio_9p_lock);
127}
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142static void req_done(struct virtqueue *vq)
143{
144 struct virtio_chan *chan = vq->vdev->priv;
145 unsigned int len;
146 struct p9_req_t *req;
147 unsigned long flags;
148
149 p9_debug(P9_DEBUG_TRANS, ": request done\n");
150
151 while (1) {
152 spin_lock_irqsave(&chan->lock, flags);
153 req = virtqueue_get_buf(chan->vq, &len);
154 if (req == NULL) {
155 spin_unlock_irqrestore(&chan->lock, flags);
156 break;
157 }
158 chan->ring_bufs_avail = 1;
159 spin_unlock_irqrestore(&chan->lock, flags);
160
161 wake_up(chan->vc_wq);
162 if (len)
163 p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
164 }
165}
166
167
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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
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
204static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
205{
206 return 1;
207}
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216
217
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
230
231
232 while (nr_pages) {
233 s = PAGE_SIZE - data_off;
234 if (s > count)
235 s = count;
236
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
251
252
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
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_killable(*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
327
328
329 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
330 err = wait_event_killable(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
344 int index;
345 size_t len;
346 void *p;
347
348
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
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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
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
451
452
453
454
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_killable(*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_killable(*req->wq, req->status >= REQ_STATUS_RCVD);
493
494
495
496err_out:
497 if (need_drop) {
498 if (in_pages) {
499 p9_release_pages(in_pages, in_nr_pages);
500 atomic_sub(in_nr_pages, &vp_pinned);
501 }
502 if (out_pages) {
503 p9_release_pages(out_pages, out_nr_pages);
504 atomic_sub(out_nr_pages, &vp_pinned);
505 }
506
507 wake_up(&vp_wq);
508 }
509 kvfree(in_pages);
510 kvfree(out_pages);
511 return err;
512}
513
514static ssize_t p9_mount_tag_show(struct device *dev,
515 struct device_attribute *attr, char *buf)
516{
517 struct virtio_chan *chan;
518 struct virtio_device *vdev;
519
520 vdev = dev_to_virtio(dev);
521 chan = vdev->priv;
522
523 memcpy(buf, chan->tag, chan->tag_len);
524 buf[chan->tag_len] = 0;
525
526 return chan->tag_len + 1;
527}
528
529static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
530
531
532
533
534
535
536
537
538
539static int p9_virtio_probe(struct virtio_device *vdev)
540{
541 __u16 tag_len;
542 char *tag;
543 int err;
544 struct virtio_chan *chan;
545
546 if (!vdev->config->get) {
547 dev_err(&vdev->dev, "%s failure: config access disabled\n",
548 __func__);
549 return -EINVAL;
550 }
551
552 chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
553 if (!chan) {
554 pr_err("Failed to allocate virtio 9P channel\n");
555 err = -ENOMEM;
556 goto fail;
557 }
558
559 chan->vdev = vdev;
560
561
562 chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
563 if (IS_ERR(chan->vq)) {
564 err = PTR_ERR(chan->vq);
565 goto out_free_vq;
566 }
567 chan->vq->vdev->priv = chan;
568 spin_lock_init(&chan->lock);
569
570 sg_init_table(chan->sg, VIRTQUEUE_NUM);
571
572 chan->inuse = false;
573 if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) {
574 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len);
575 } else {
576 err = -EINVAL;
577 goto out_free_vq;
578 }
579 tag = kmalloc(tag_len, GFP_KERNEL);
580 if (!tag) {
581 err = -ENOMEM;
582 goto out_free_vq;
583 }
584
585 virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag),
586 tag, tag_len);
587 chan->tag = tag;
588 chan->tag_len = tag_len;
589 err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
590 if (err) {
591 goto out_free_tag;
592 }
593 chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
594 if (!chan->vc_wq) {
595 err = -ENOMEM;
596 goto out_free_tag;
597 }
598 init_waitqueue_head(chan->vc_wq);
599 chan->ring_bufs_avail = 1;
600
601 chan->p9_max_pages = nr_free_buffer_pages()/4;
602
603 virtio_device_ready(vdev);
604
605 mutex_lock(&virtio_9p_lock);
606 list_add_tail(&chan->chan_list, &virtio_chan_list);
607 mutex_unlock(&virtio_9p_lock);
608
609
610 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
611
612 return 0;
613
614out_free_tag:
615 kfree(tag);
616out_free_vq:
617 vdev->config->del_vqs(vdev);
618 kfree(chan);
619fail:
620 return err;
621}
622
623
624
625
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629
630
631
632
633
634
635
636
637
638static int
639p9_virtio_create(struct p9_client *client, const char *devname, char *args)
640{
641 struct virtio_chan *chan;
642 int ret = -ENOENT;
643 int found = 0;
644
645 mutex_lock(&virtio_9p_lock);
646 list_for_each_entry(chan, &virtio_chan_list, chan_list) {
647 if (!strncmp(devname, chan->tag, chan->tag_len) &&
648 strlen(devname) == chan->tag_len) {
649 if (!chan->inuse) {
650 chan->inuse = true;
651 found = 1;
652 break;
653 }
654 ret = -EBUSY;
655 }
656 }
657 mutex_unlock(&virtio_9p_lock);
658
659 if (!found) {
660 pr_err("no channels available for device %s\n", devname);
661 return ret;
662 }
663
664 client->trans = (void *)chan;
665 client->status = Connected;
666 chan->client = client;
667
668 return 0;
669}
670
671
672
673
674
675
676
677static void p9_virtio_remove(struct virtio_device *vdev)
678{
679 struct virtio_chan *chan = vdev->priv;
680 unsigned long warning_time;
681
682 mutex_lock(&virtio_9p_lock);
683
684
685 list_del(&chan->chan_list);
686 warning_time = jiffies;
687
688
689 while (chan->inuse) {
690 mutex_unlock(&virtio_9p_lock);
691 msleep(250);
692 if (time_after(jiffies, warning_time + 10 * HZ)) {
693 dev_emerg(&vdev->dev,
694 "p9_virtio_remove: waiting for device in use.\n");
695 warning_time = jiffies;
696 }
697 mutex_lock(&virtio_9p_lock);
698 }
699
700 mutex_unlock(&virtio_9p_lock);
701
702 vdev->config->reset(vdev);
703 vdev->config->del_vqs(vdev);
704
705 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
706 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
707 kfree(chan->tag);
708 kfree(chan->vc_wq);
709 kfree(chan);
710
711}
712
713static struct virtio_device_id id_table[] = {
714 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
715 { 0 },
716};
717
718static unsigned int features[] = {
719 VIRTIO_9P_MOUNT_TAG,
720};
721
722
723static struct virtio_driver p9_virtio_drv = {
724 .feature_table = features,
725 .feature_table_size = ARRAY_SIZE(features),
726 .driver.name = KBUILD_MODNAME,
727 .driver.owner = THIS_MODULE,
728 .id_table = id_table,
729 .probe = p9_virtio_probe,
730 .remove = p9_virtio_remove,
731};
732
733static struct p9_trans_module p9_virtio_trans = {
734 .name = "virtio",
735 .create = p9_virtio_create,
736 .close = p9_virtio_close,
737 .request = p9_virtio_request,
738 .zc_request = p9_virtio_zc_request,
739 .cancel = p9_virtio_cancel,
740
741
742
743
744
745
746 .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),
747 .def = 1,
748 .owner = THIS_MODULE,
749};
750
751
752static int __init p9_virtio_init(void)
753{
754 INIT_LIST_HEAD(&virtio_chan_list);
755
756 v9fs_register_trans(&p9_virtio_trans);
757 return register_virtio_driver(&p9_virtio_drv);
758}
759
760static void __exit p9_virtio_cleanup(void)
761{
762 unregister_virtio_driver(&p9_virtio_drv);
763 v9fs_unregister_trans(&p9_virtio_trans);
764}
765
766module_init(p9_virtio_init);
767module_exit(p9_virtio_cleanup);
768
769MODULE_DEVICE_TABLE(virtio, id_table);
770MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
771MODULE_DESCRIPTION("Virtio 9p Transport");
772MODULE_LICENSE("GPL");
773