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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 if (addr == NULL)
98 return -EINVAL;
99
100 read_lock(&xen_9pfs_lock);
101 list_for_each_entry(priv, &xen_9pfs_devs, list) {
102 if (!strcmp(priv->tag, addr)) {
103 priv->client = client;
104 read_unlock(&xen_9pfs_lock);
105 return 0;
106 }
107 }
108 read_unlock(&xen_9pfs_lock);
109 return -EINVAL;
110}
111
112static void p9_xen_close(struct p9_client *client)
113{
114 struct xen_9pfs_front_priv *priv;
115
116 read_lock(&xen_9pfs_lock);
117 list_for_each_entry(priv, &xen_9pfs_devs, list) {
118 if (priv->client == client) {
119 priv->client = NULL;
120 read_unlock(&xen_9pfs_lock);
121 return;
122 }
123 }
124 read_unlock(&xen_9pfs_lock);
125}
126
127static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size)
128{
129 RING_IDX cons, prod;
130
131 cons = ring->intf->out_cons;
132 prod = ring->intf->out_prod;
133 virt_mb();
134
135 return XEN_9PFS_RING_SIZE -
136 xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) >= size;
137}
138
139static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
140{
141 struct xen_9pfs_front_priv *priv = NULL;
142 RING_IDX cons, prod, masked_cons, masked_prod;
143 unsigned long flags;
144 u32 size = p9_req->tc.size;
145 struct xen_9pfs_dataring *ring;
146 int num;
147
148 read_lock(&xen_9pfs_lock);
149 list_for_each_entry(priv, &xen_9pfs_devs, list) {
150 if (priv->client == client)
151 break;
152 }
153 read_unlock(&xen_9pfs_lock);
154 if (!priv || priv->client != client)
155 return -EINVAL;
156
157 num = p9_req->tc.tag % priv->num_rings;
158 ring = &priv->rings[num];
159
160again:
161 while (wait_event_killable(ring->wq,
162 p9_xen_write_todo(ring, size)) != 0)
163 ;
164
165 spin_lock_irqsave(&ring->lock, flags);
166 cons = ring->intf->out_cons;
167 prod = ring->intf->out_prod;
168 virt_mb();
169
170 if (XEN_9PFS_RING_SIZE - xen_9pfs_queued(prod, cons,
171 XEN_9PFS_RING_SIZE) < size) {
172 spin_unlock_irqrestore(&ring->lock, flags);
173 goto again;
174 }
175
176 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE);
177 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE);
178
179 xen_9pfs_write_packet(ring->data.out, p9_req->tc.sdata, size,
180 &masked_prod, masked_cons, XEN_9PFS_RING_SIZE);
181
182 p9_req->status = REQ_STATUS_SENT;
183 virt_wmb();
184 prod += size;
185 ring->intf->out_prod = prod;
186 spin_unlock_irqrestore(&ring->lock, flags);
187 notify_remote_via_irq(ring->irq);
188 p9_req_put(p9_req);
189
190 return 0;
191}
192
193static void p9_xen_response(struct work_struct *work)
194{
195 struct xen_9pfs_front_priv *priv;
196 struct xen_9pfs_dataring *ring;
197 RING_IDX cons, prod, masked_cons, masked_prod;
198 struct xen_9pfs_header h;
199 struct p9_req_t *req;
200 int status;
201
202 ring = container_of(work, struct xen_9pfs_dataring, work);
203 priv = ring->priv;
204
205 while (1) {
206 cons = ring->intf->in_cons;
207 prod = ring->intf->in_prod;
208 virt_rmb();
209
210 if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) <
211 sizeof(h)) {
212 notify_remote_via_irq(ring->irq);
213 return;
214 }
215
216 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE);
217 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE);
218
219
220 xen_9pfs_read_packet(&h, ring->data.in, sizeof(h),
221 masked_prod, &masked_cons,
222 XEN_9PFS_RING_SIZE);
223
224 req = p9_tag_lookup(priv->client, h.tag);
225 if (!req || req->status != REQ_STATUS_SENT) {
226 dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag);
227 cons += h.size;
228 virt_mb();
229 ring->intf->in_cons = cons;
230 continue;
231 }
232
233 memcpy(&req->rc, &h, sizeof(h));
234 req->rc.offset = 0;
235
236 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE);
237
238 xen_9pfs_read_packet(req->rc.sdata, ring->data.in, h.size,
239 masked_prod, &masked_cons,
240 XEN_9PFS_RING_SIZE);
241
242 virt_mb();
243 cons += h.size;
244 ring->intf->in_cons = cons;
245
246 status = (req->status != REQ_STATUS_ERROR) ?
247 REQ_STATUS_RCVD : REQ_STATUS_ERROR;
248
249 p9_client_cb(priv->client, req, status);
250 }
251}
252
253static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r)
254{
255 struct xen_9pfs_dataring *ring = r;
256
257 if (!ring || !ring->priv->client) {
258
259 return IRQ_HANDLED;
260 }
261
262 wake_up_interruptible(&ring->wq);
263 schedule_work(&ring->work);
264
265 return IRQ_HANDLED;
266}
267
268static struct p9_trans_module p9_xen_trans = {
269 .name = "xen",
270 .maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT),
271 .def = 1,
272 .create = p9_xen_create,
273 .close = p9_xen_close,
274 .request = p9_xen_request,
275 .cancel = p9_xen_cancel,
276 .owner = THIS_MODULE,
277};
278
279static const struct xenbus_device_id xen_9pfs_front_ids[] = {
280 { "9pfs" },
281 { "" }
282};
283
284static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
285{
286 int i, j;
287
288 write_lock(&xen_9pfs_lock);
289 list_del(&priv->list);
290 write_unlock(&xen_9pfs_lock);
291
292 for (i = 0; i < priv->num_rings; i++) {
293 if (!priv->rings[i].intf)
294 break;
295 if (priv->rings[i].irq > 0)
296 unbind_from_irqhandler(priv->rings[i].irq, priv->dev);
297 if (priv->rings[i].data.in) {
298 for (j = 0; j < (1 << XEN_9PFS_RING_ORDER); j++) {
299 grant_ref_t ref;
300
301 ref = priv->rings[i].intf->ref[j];
302 gnttab_end_foreign_access(ref, 0, 0);
303 }
304 free_pages((unsigned long)priv->rings[i].data.in,
305 XEN_9PFS_RING_ORDER -
306 (PAGE_SHIFT - XEN_PAGE_SHIFT));
307 }
308 gnttab_end_foreign_access(priv->rings[i].ref, 0, 0);
309 free_page((unsigned long)priv->rings[i].intf);
310 }
311 kfree(priv->rings);
312 kfree(priv->tag);
313 kfree(priv);
314}
315
316static int xen_9pfs_front_remove(struct xenbus_device *dev)
317{
318 struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
319
320 dev_set_drvdata(&dev->dev, NULL);
321 xen_9pfs_front_free(priv);
322 return 0;
323}
324
325static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
326 struct xen_9pfs_dataring *ring)
327{
328 int i = 0;
329 int ret = -ENOMEM;
330 void *bytes = NULL;
331
332 init_waitqueue_head(&ring->wq);
333 spin_lock_init(&ring->lock);
334 INIT_WORK(&ring->work, p9_xen_response);
335
336 ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL);
337 if (!ring->intf)
338 return ret;
339 ret = gnttab_grant_foreign_access(dev->otherend_id,
340 virt_to_gfn(ring->intf), 0);
341 if (ret < 0)
342 goto out;
343 ring->ref = ret;
344 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
345 XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT));
346 if (!bytes) {
347 ret = -ENOMEM;
348 goto out;
349 }
350 for (; i < (1 << XEN_9PFS_RING_ORDER); i++) {
351 ret = gnttab_grant_foreign_access(
352 dev->otherend_id, virt_to_gfn(bytes) + i, 0);
353 if (ret < 0)
354 goto out;
355 ring->intf->ref[i] = ret;
356 }
357 ring->intf->ring_order = XEN_9PFS_RING_ORDER;
358 ring->data.in = bytes;
359 ring->data.out = bytes + XEN_9PFS_RING_SIZE;
360
361 ret = xenbus_alloc_evtchn(dev, &ring->evtchn);
362 if (ret)
363 goto out;
364 ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
365 xen_9pfs_front_event_handler,
366 0, "xen_9pfs-frontend", ring);
367 if (ring->irq >= 0)
368 return 0;
369
370 xenbus_free_evtchn(dev, ring->evtchn);
371 ret = ring->irq;
372out:
373 if (bytes) {
374 for (i--; i >= 0; i--)
375 gnttab_end_foreign_access(ring->intf->ref[i], 0, 0);
376 free_pages((unsigned long)bytes,
377 XEN_9PFS_RING_ORDER -
378 (PAGE_SHIFT - XEN_PAGE_SHIFT));
379 }
380 gnttab_end_foreign_access(ring->ref, 0, 0);
381 free_page((unsigned long)ring->intf);
382 return ret;
383}
384
385static int xen_9pfs_front_probe(struct xenbus_device *dev,
386 const struct xenbus_device_id *id)
387{
388 int ret, i;
389 struct xenbus_transaction xbt;
390 struct xen_9pfs_front_priv *priv = NULL;
391 char *versions;
392 unsigned int max_rings, max_ring_order, len = 0;
393
394 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
395 if (IS_ERR(versions))
396 return PTR_ERR(versions);
397 if (strcmp(versions, "1")) {
398 kfree(versions);
399 return -EINVAL;
400 }
401 kfree(versions);
402 max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0);
403 if (max_rings < XEN_9PFS_NUM_RINGS)
404 return -EINVAL;
405 max_ring_order = xenbus_read_unsigned(dev->otherend,
406 "max-ring-page-order", 0);
407 if (max_ring_order < XEN_9PFS_RING_ORDER)
408 return -EINVAL;
409
410 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
411 if (!priv)
412 return -ENOMEM;
413
414 priv->dev = dev;
415 priv->num_rings = XEN_9PFS_NUM_RINGS;
416 priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings),
417 GFP_KERNEL);
418 if (!priv->rings) {
419 kfree(priv);
420 return -ENOMEM;
421 }
422
423 for (i = 0; i < priv->num_rings; i++) {
424 priv->rings[i].priv = priv;
425 ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i]);
426 if (ret < 0)
427 goto error;
428 }
429
430 again:
431 ret = xenbus_transaction_start(&xbt);
432 if (ret) {
433 xenbus_dev_fatal(dev, ret, "starting transaction");
434 goto error;
435 }
436 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
437 if (ret)
438 goto error_xenbus;
439 ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u",
440 priv->num_rings);
441 if (ret)
442 goto error_xenbus;
443 for (i = 0; i < priv->num_rings; i++) {
444 char str[16];
445
446 BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9);
447 sprintf(str, "ring-ref%u", i);
448 ret = xenbus_printf(xbt, dev->nodename, str, "%d",
449 priv->rings[i].ref);
450 if (ret)
451 goto error_xenbus;
452
453 sprintf(str, "event-channel-%u", i);
454 ret = xenbus_printf(xbt, dev->nodename, str, "%u",
455 priv->rings[i].evtchn);
456 if (ret)
457 goto error_xenbus;
458 }
459 priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL);
460 if (IS_ERR(priv->tag)) {
461 ret = PTR_ERR(priv->tag);
462 goto error_xenbus;
463 }
464 ret = xenbus_transaction_end(xbt, 0);
465 if (ret) {
466 if (ret == -EAGAIN)
467 goto again;
468 xenbus_dev_fatal(dev, ret, "completing transaction");
469 goto error;
470 }
471
472 write_lock(&xen_9pfs_lock);
473 list_add_tail(&priv->list, &xen_9pfs_devs);
474 write_unlock(&xen_9pfs_lock);
475 dev_set_drvdata(&dev->dev, priv);
476 xenbus_switch_state(dev, XenbusStateInitialised);
477
478 return 0;
479
480 error_xenbus:
481 xenbus_transaction_end(xbt, 1);
482 xenbus_dev_fatal(dev, ret, "writing xenstore");
483 error:
484 dev_set_drvdata(&dev->dev, NULL);
485 xen_9pfs_front_free(priv);
486 return ret;
487}
488
489static int xen_9pfs_front_resume(struct xenbus_device *dev)
490{
491 dev_warn(&dev->dev, "suspend/resume unsupported\n");
492 return 0;
493}
494
495static void xen_9pfs_front_changed(struct xenbus_device *dev,
496 enum xenbus_state backend_state)
497{
498 switch (backend_state) {
499 case XenbusStateReconfiguring:
500 case XenbusStateReconfigured:
501 case XenbusStateInitialising:
502 case XenbusStateInitialised:
503 case XenbusStateUnknown:
504 break;
505
506 case XenbusStateInitWait:
507 break;
508
509 case XenbusStateConnected:
510 xenbus_switch_state(dev, XenbusStateConnected);
511 break;
512
513 case XenbusStateClosed:
514 if (dev->state == XenbusStateClosed)
515 break;
516
517 case XenbusStateClosing:
518 xenbus_frontend_closed(dev);
519 break;
520 }
521}
522
523static struct xenbus_driver xen_9pfs_front_driver = {
524 .ids = xen_9pfs_front_ids,
525 .probe = xen_9pfs_front_probe,
526 .remove = xen_9pfs_front_remove,
527 .resume = xen_9pfs_front_resume,
528 .otherend_changed = xen_9pfs_front_changed,
529};
530
531static int p9_trans_xen_init(void)
532{
533 if (!xen_domain())
534 return -ENODEV;
535
536 pr_info("Initialising Xen transport for 9pfs\n");
537
538 v9fs_register_trans(&p9_xen_trans);
539 return xenbus_register_frontend(&xen_9pfs_front_driver);
540}
541module_init(p9_trans_xen_init);
542
543static void p9_trans_xen_exit(void)
544{
545 v9fs_unregister_trans(&p9_xen_trans);
546 return xenbus_unregister_driver(&xen_9pfs_front_driver);
547}
548module_exit(p9_trans_xen_exit);
549
550MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>");
551MODULE_DESCRIPTION("Xen Transport for 9P");
552MODULE_LICENSE("GPL");
553
