~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/net/9p/trans_xen.c

Version: ~ [ linux-5.9 ] ~ [ linux-5.8.14 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.70 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.150 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.200 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.238 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.238 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /*
  2  * linux/fs/9p/trans_xen
  3  *
  4  * Xen transport layer.
  5  *
  6  * Copyright (C) 2017 by Stefano Stabellini <stefano@aporeto.com>
  7  *
  8  * This program is free software; you can redistribute it and/or
  9  * modify it under the terms of the GNU General Public License version 2
 10  * as published by the Free Software Foundation; or, when distributed
 11  * separately from the Linux kernel or incorporated into other
 12  * software packages, subject to the following license:
 13  *
 14  * Permission is hereby granted, free of charge, to any person obtaining a copy
 15  * of this source file (the "Software"), to deal in the Software without
 16  * restriction, including without limitation the rights to use, copy, modify,
 17  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 18  * and to permit persons to whom the Software is furnished to do so, subject to
 19  * the following conditions:
 20  *
 21  * The above copyright notice and this permission notice shall be included in
 22  * all copies or substantial portions of the Software.
 23  *
 24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 25  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 26  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 27  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 28  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 29  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 30  * IN THE SOFTWARE.
 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 
 49 struct xen_9pfs_header {
 50         uint32_t size;
 51         uint8_t id;
 52         uint16_t tag;
 53 
 54         /* uint8_t sdata[]; */
 55 } __attribute__((packed));
 56 
 57 /* One per ring, more than one per 9pfs share */
 58 struct 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         /* protect a ring from concurrent accesses */
 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 /* One per 9pfs share */
 74 struct 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 
 84 static LIST_HEAD(xen_9pfs_devs);
 85 static DEFINE_RWLOCK(xen_9pfs_lock);
 86 
 87 /* We don't currently allow canceling of requests */
 88 static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req)
 89 {
 90         return 1;
 91 }
 92 
 93 static 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 
112 static 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 
127 static 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 
139 static 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 
160 again:
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();                     /* write ring before updating pointer */
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 
193 static 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                 /* First, read just the header */
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                 /* Then, read the whole packet (including the header) */
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 
253 static 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                 /* ignore spurious interrupt */
259                 return IRQ_HANDLED;
260         }
261 
262         wake_up_interruptible(&ring->wq);
263         schedule_work(&ring->work);
264 
265         return IRQ_HANDLED;
266 }
267 
268 static 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 
279 static const struct xenbus_device_id xen_9pfs_front_ids[] = {
280         { "9pfs" },
281         { "" }
282 };
283 
284 static 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 
316 static 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 
325 static 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;
372 out:
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 
385 static 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 
489 static int xen_9pfs_front_resume(struct xenbus_device *dev)
490 {
491         dev_warn(&dev->dev, "suspend/resume unsupported\n");
492         return 0;
493 }
494 
495 static 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                 /* fall through - Missed the backend's CLOSING state */
517         case XenbusStateClosing:
518                 xenbus_frontend_closed(dev);
519                 break;
520         }
521 }
522 
523 static 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 
531 static int p9_trans_xen_init(void)
532 {
533         int rc;
534 
535         if (!xen_domain())
536                 return -ENODEV;
537 
538         pr_info("Initialising Xen transport for 9pfs\n");
539 
540         v9fs_register_trans(&p9_xen_trans);
541         rc = xenbus_register_frontend(&xen_9pfs_front_driver);
542         if (rc)
543                 v9fs_unregister_trans(&p9_xen_trans);
544 
545         return rc;
546 }
547 module_init(p9_trans_xen_init);
548 
549 static void p9_trans_xen_exit(void)
550 {
551         v9fs_unregister_trans(&p9_xen_trans);
552         return xenbus_unregister_driver(&xen_9pfs_front_driver);
553 }
554 module_exit(p9_trans_xen_exit);
555 
556 MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>");
557 MODULE_DESCRIPTION("Xen Transport for 9P");
558 MODULE_LICENSE("GPL");
559 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp