1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33#include <xen/events.h>
34#include <xen/grant_table.h>
35#include <xen/xen.h>
36#include <xen/xenbus.h>
37#include <xen/interface/io/9pfs.h>
38
39#include <linux/module.h>
40#include <linux/spinlock.h>
41#include <net/9p/9p.h>
42#include <net/9p/client.h>
43#include <net/9p/transport.h>
44
45#define XEN_9PFS_NUM_RINGS 2
46#define XEN_9PFS_RING_ORDER 6
47#define XEN_9PFS_RING_SIZE XEN_FLEX_RING_SIZE(XEN_9PFS_RING_ORDER)
48
49struct xen_9pfs_header {
50 uint32_t size;
51 uint8_t id;
52 uint16_t tag;
53
54
55} __attribute__((packed));
56
57
58struct xen_9pfs_dataring {
59 struct xen_9pfs_front_priv *priv;
60
61 struct xen_9pfs_data_intf *intf;
62 grant_ref_t ref;
63 int evtchn;
64 int irq;
65
66 spinlock_t lock;
67
68 struct xen_9pfs_data data;
69 wait_queue_head_t wq;
70 struct work_struct work;
71};
72
73
74struct xen_9pfs_front_priv {
75 struct list_head list;
76 struct xenbus_device *dev;
77 char *tag;
78 struct p9_client *client;
79
80 int num_rings;
81 struct xen_9pfs_dataring *rings;
82};
83
84static LIST_HEAD(xen_9pfs_devs);
85static DEFINE_RWLOCK(xen_9pfs_lock);
86
87
88static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req)
89{
90 return 1;
91}
92
93static int p9_xen_create(struct p9_client *client, const char *addr, char *args)
94{
95 struct xen_9pfs_front_priv *priv;
96
97 read_lock(&xen_9pfs_lock);
98 list_for_each_entry(priv, &xen_9pfs_devs, list) {
99 if (!strcmp(priv->tag, addr)) {
100 priv->client = client;
101 read_unlock(&xen_9pfs_lock);
102 return 0;
103 }
104 }
105 read_unlock(&xen_9pfs_lock);
106 return -EINVAL;
107}
108
109static void p9_xen_close(struct p9_client *client)
110{
111 struct xen_9pfs_front_priv *priv;
112
113 read_lock(&xen_9pfs_lock);
114 list_for_each_entry(priv, &xen_9pfs_devs, list) {
115 if (priv->client == client) {
116 priv->client = NULL;
117 read_unlock(&xen_9pfs_lock);
118 return;
119 }
120 }
121 read_unlock(&xen_9pfs_lock);
122}
123
124static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size)
125{
126 RING_IDX cons, prod;
127
128 cons = ring->intf->out_cons;
129 prod = ring->intf->out_prod;
130 virt_mb();
131
132 return XEN_9PFS_RING_SIZE -
133 xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) >= size;
134}
135
136static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
137{
138 struct xen_9pfs_front_priv *priv = NULL;
139 RING_IDX cons, prod, masked_cons, masked_prod;
140 unsigned long flags;
141 u32 size = p9_req->tc->size;
142 struct xen_9pfs_dataring *ring;
143 int num;
144
145 read_lock(&xen_9pfs_lock);
146 list_for_each_entry(priv, &xen_9pfs_devs, list) {
147 if (priv->client == client)
148 break;
149 }
150 read_unlock(&xen_9pfs_lock);
151 if (!priv || priv->client != client)
152 return -EINVAL;
153
154 num = p9_req->tc->tag % priv->num_rings;
155 ring = &priv->rings[num];
156
157again:
158 while (wait_event_killable(ring->wq,
159 p9_xen_write_todo(ring, size)) != 0)
160 ;
161
162 spin_lock_irqsave(&ring->lock, flags);
163 cons = ring->intf->out_cons;
164 prod = ring->intf->out_prod;
165 virt_mb();
166
167 if (XEN_9PFS_RING_SIZE - xen_9pfs_queued(prod, cons,
168 XEN_9PFS_RING_SIZE) < size) {
169 spin_unlock_irqrestore(&ring->lock, flags);
170 goto again;
171 }
172
173 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE);
174 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE);
175
176 xen_9pfs_write_packet(ring->data.out, p9_req->tc->sdata, size,
177 &masked_prod, masked_cons, XEN_9PFS_RING_SIZE);
178
179 p9_req->status = REQ_STATUS_SENT;
180 virt_wmb();
181 prod += size;
182 ring->intf->out_prod = prod;
183 spin_unlock_irqrestore(&ring->lock, flags);
184 notify_remote_via_irq(ring->irq);
185
186 return 0;
187}
188
189static void p9_xen_response(struct work_struct *work)
190{
191 struct xen_9pfs_front_priv *priv;
192 struct xen_9pfs_dataring *ring;
193 RING_IDX cons, prod, masked_cons, masked_prod;
194 struct xen_9pfs_header h;
195 struct p9_req_t *req;
196 int status;
197
198 ring = container_of(work, struct xen_9pfs_dataring, work);
199 priv = ring->priv;
200
201 while (1) {
202 cons = ring->intf->in_cons;
203 prod = ring->intf->in_prod;
204 virt_rmb();
205
206 if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) <
207 sizeof(h)) {
208 notify_remote_via_irq(ring->irq);
209 return;
210 }
211
212 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE);
213 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE);
214
215
216 xen_9pfs_read_packet(&h, ring->data.in, sizeof(h),
217 masked_prod, &masked_cons,
218 XEN_9PFS_RING_SIZE);
219
220 req = p9_tag_lookup(priv->client, h.tag);
221 if (!req || req->status != REQ_STATUS_SENT) {
222 dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag);
223 cons += h.size;
224 virt_mb();
225 ring->intf->in_cons = cons;
226 continue;
227 }
228
229 memcpy(req->rc, &h, sizeof(h));
230 req->rc->offset = 0;
231
232 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE);
233
234 xen_9pfs_read_packet(req->rc->sdata, ring->data.in, h.size,
235 masked_prod, &masked_cons,
236 XEN_9PFS_RING_SIZE);
237
238 virt_mb();
239 cons += h.size;
240 ring->intf->in_cons = cons;
241
242 status = (req->status != REQ_STATUS_ERROR) ?
243 REQ_STATUS_RCVD : REQ_STATUS_ERROR;
244
245 p9_client_cb(priv->client, req, status);
246 }
247}
248
249static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r)
250{
251 struct xen_9pfs_dataring *ring = r;
252
253 if (!ring || !ring->priv->client) {
254
255 return IRQ_HANDLED;
256 }
257
258 wake_up_interruptible(&ring->wq);
259 schedule_work(&ring->work);
260
261 return IRQ_HANDLED;
262}
263
264static struct p9_trans_module p9_xen_trans = {
265 .name = "xen",
266 .maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT),
267 .def = 1,
268 .create = p9_xen_create,
269 .close = p9_xen_close,
270 .request = p9_xen_request,
271 .cancel = p9_xen_cancel,
272 .owner = THIS_MODULE,
273};
274
275static const struct xenbus_device_id xen_9pfs_front_ids[] = {
276 { "9pfs" },
277 { "" }
278};
279
280static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
281{
282 int i, j;
283
284 write_lock(&xen_9pfs_lock);
285 list_del(&priv->list);
286 write_unlock(&xen_9pfs_lock);
287
288 for (i = 0; i < priv->num_rings; i++) {
289 if (!priv->rings[i].intf)
290 break;
291 if (priv->rings[i].irq > 0)
292 unbind_from_irqhandler(priv->rings[i].irq, priv->dev);
293 if (priv->rings[i].data.in) {
294 for (j = 0; j < (1 << XEN_9PFS_RING_ORDER); j++) {
295 grant_ref_t ref;
296
297 ref = priv->rings[i].intf->ref[j];
298 gnttab_end_foreign_access(ref, 0, 0);
299 }
300 free_pages((unsigned long)priv->rings[i].data.in,
301 XEN_9PFS_RING_ORDER -
302 (PAGE_SHIFT - XEN_PAGE_SHIFT));
303 }
304 gnttab_end_foreign_access(priv->rings[i].ref, 0, 0);
305 free_page((unsigned long)priv->rings[i].intf);
306 }
307 kfree(priv->rings);
308 kfree(priv->tag);
309 kfree(priv);
310}
311
312static int xen_9pfs_front_remove(struct xenbus_device *dev)
313{
314 struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
315
316 dev_set_drvdata(&dev->dev, NULL);
317 xen_9pfs_front_free(priv);
318 return 0;
319}
320
321static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
322 struct xen_9pfs_dataring *ring)
323{
324 int i = 0;
325 int ret = -ENOMEM;
326 void *bytes = NULL;
327
328 init_waitqueue_head(&ring->wq);
329 spin_lock_init(&ring->lock);
330 INIT_WORK(&ring->work, p9_xen_response);
331
332 ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL);
333 if (!ring->intf)
334 return ret;
335 ret = gnttab_grant_foreign_access(dev->otherend_id,
336 virt_to_gfn(ring->intf), 0);
337 if (ret < 0)
338 goto out;
339 ring->ref = ret;
340 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
341 XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT));
342 if (!bytes) {
343 ret = -ENOMEM;
344 goto out;
345 }
346 for (; i < (1 << XEN_9PFS_RING_ORDER); i++) {
347 ret = gnttab_grant_foreign_access(
348 dev->otherend_id, virt_to_gfn(bytes) + i, 0);
349 if (ret < 0)
350 goto out;
351 ring->intf->ref[i] = ret;
352 }
353 ring->intf->ring_order = XEN_9PFS_RING_ORDER;
354 ring->data.in = bytes;
355 ring->data.out = bytes + XEN_9PFS_RING_SIZE;
356
357 ret = xenbus_alloc_evtchn(dev, &ring->evtchn);
358 if (ret)
359 goto out;
360 ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
361 xen_9pfs_front_event_handler,
362 0, "xen_9pfs-frontend", ring);
363 if (ring->irq >= 0)
364 return 0;
365
366 xenbus_free_evtchn(dev, ring->evtchn);
367 ret = ring->irq;
368out:
369 if (bytes) {
370 for (i--; i >= 0; i--)
371 gnttab_end_foreign_access(ring->intf->ref[i], 0, 0);
372 free_pages((unsigned long)bytes,
373 XEN_9PFS_RING_ORDER -
374 (PAGE_SHIFT - XEN_PAGE_SHIFT));
375 }
376 gnttab_end_foreign_access(ring->ref, 0, 0);
377 free_page((unsigned long)ring->intf);
378 return ret;
379}
380
381static int xen_9pfs_front_probe(struct xenbus_device *dev,
382 const struct xenbus_device_id *id)
383{
384 int ret, i;
385 struct xenbus_transaction xbt;
386 struct xen_9pfs_front_priv *priv = NULL;
387 char *versions;
388 unsigned int max_rings, max_ring_order, len = 0;
389
390 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
391 if (!len)
392 return -EINVAL;
393 if (strcmp(versions, "1")) {
394 kfree(versions);
395 return -EINVAL;
396 }
397 kfree(versions);
398 max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0);
399 if (max_rings < XEN_9PFS_NUM_RINGS)
400 return -EINVAL;
401 max_ring_order = xenbus_read_unsigned(dev->otherend,
402 "max-ring-page-order", 0);
403 if (max_ring_order < XEN_9PFS_RING_ORDER)
404 return -EINVAL;
405
406 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
407 if (!priv)
408 return -ENOMEM;
409
410 priv->dev = dev;
411 priv->num_rings = XEN_9PFS_NUM_RINGS;
412 priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings),
413 GFP_KERNEL);
414 if (!priv->rings) {
415 kfree(priv);
416 return -ENOMEM;
417 }
418
419 for (i = 0; i < priv->num_rings; i++) {
420 priv->rings[i].priv = priv;
421 ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i]);
422 if (ret < 0)
423 goto error;
424 }
425
426 again:
427 ret = xenbus_transaction_start(&xbt);
428 if (ret) {
429 xenbus_dev_fatal(dev, ret, "starting transaction");
430 goto error;
431 }
432 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
433 if (ret)
434 goto error_xenbus;
435 ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u",
436 priv->num_rings);
437 if (ret)
438 goto error_xenbus;
439 for (i = 0; i < priv->num_rings; i++) {
440 char str[16];
441
442 BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9);
443 sprintf(str, "ring-ref%u", i);
444 ret = xenbus_printf(xbt, dev->nodename, str, "%d",
445 priv->rings[i].ref);
446 if (ret)
447 goto error_xenbus;
448
449 sprintf(str, "event-channel-%u", i);
450 ret = xenbus_printf(xbt, dev->nodename, str, "%u",
451 priv->rings[i].evtchn);
452 if (ret)
453 goto error_xenbus;
454 }
455 priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL);
456 if (IS_ERR(priv->tag)) {
457 ret = PTR_ERR(priv->tag);
458 goto error_xenbus;
459 }
460 ret = xenbus_transaction_end(xbt, 0);
461 if (ret) {
462 if (ret == -EAGAIN)
463 goto again;
464 xenbus_dev_fatal(dev, ret, "completing transaction");
465 goto error;
466 }
467
468 write_lock(&xen_9pfs_lock);
469 list_add_tail(&priv->list, &xen_9pfs_devs);
470 write_unlock(&xen_9pfs_lock);
471 dev_set_drvdata(&dev->dev, priv);
472 xenbus_switch_state(dev, XenbusStateInitialised);
473
474 return 0;
475
476 error_xenbus:
477 xenbus_transaction_end(xbt, 1);
478 xenbus_dev_fatal(dev, ret, "writing xenstore");
479 error:
480 dev_set_drvdata(&dev->dev, NULL);
481 xen_9pfs_front_free(priv);
482 return ret;
483}
484
485static int xen_9pfs_front_resume(struct xenbus_device *dev)
486{
487 dev_warn(&dev->dev, "suspend/resume unsupported\n");
488 return 0;
489}
490
491static void xen_9pfs_front_changed(struct xenbus_device *dev,
492 enum xenbus_state backend_state)
493{
494 switch (backend_state) {
495 case XenbusStateReconfiguring:
496 case XenbusStateReconfigured:
497 case XenbusStateInitialising:
498 case XenbusStateInitialised:
499 case XenbusStateUnknown:
500 break;
501
502 case XenbusStateInitWait:
503 break;
504
505 case XenbusStateConnected:
506 xenbus_switch_state(dev, XenbusStateConnected);
507 break;
508
509 case XenbusStateClosed:
510 if (dev->state == XenbusStateClosed)
511 break;
512
513 case XenbusStateClosing:
514 xenbus_frontend_closed(dev);
515 break;
516 }
517}
518
519static struct xenbus_driver xen_9pfs_front_driver = {
520 .ids = xen_9pfs_front_ids,
521 .probe = xen_9pfs_front_probe,
522 .remove = xen_9pfs_front_remove,
523 .resume = xen_9pfs_front_resume,
524 .otherend_changed = xen_9pfs_front_changed,
525};
526
527static int p9_trans_xen_init(void)
528{
529 if (!xen_domain())
530 return -ENODEV;
531
532 pr_info("Initialising Xen transport for 9pfs\n");
533
534 v9fs_register_trans(&p9_xen_trans);
535 return xenbus_register_frontend(&xen_9pfs_front_driver);
536}
537module_init(p9_trans_xen_init);
538
539static void p9_trans_xen_exit(void)
540{
541 v9fs_unregister_trans(&p9_xen_trans);
542 return xenbus_unregister_driver(&xen_9pfs_front_driver);
543}
544module_exit(p9_trans_xen_exit);
545
546MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>");
547MODULE_DESCRIPTION("Xen Transport for 9P");
548MODULE_LICENSE("GPL");
549
