2 * linux/fs/9p/trans_xen
6 * Copyright (C) 2017 by Stefano Stabellini <stefano@aporeto.com>
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:
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:
21 * The above copyright notice and this permission notice shall be included in
22 * all copies or substantial portions of the Software.
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
33 #include <xen/events.h>
34 #include <xen/grant_table.h>
36 #include <xen/xenbus.h>
37 #include <xen/interface/io/9pfs.h>
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>
45 #define XEN_9PFS_NUM_RINGS 2
46 #define XEN_9PFS_RING_ORDER 9
47 #define XEN_9PFS_RING_SIZE(ring) XEN_FLEX_RING_SIZE(ring->intf->ring_order)
49 struct xen_9pfs_header {
54 /* uint8_t sdata[]; */
55 } __attribute__((packed));
57 /* One per ring, more than one per 9pfs share */
58 struct xen_9pfs_dataring {
59 struct xen_9pfs_front_priv *priv;
61 struct xen_9pfs_data_intf *intf;
65 /* protect a ring from concurrent accesses */
68 struct xen_9pfs_data data;
70 struct work_struct work;
73 /* One per 9pfs share */
74 struct xen_9pfs_front_priv {
75 struct list_head list;
76 struct xenbus_device *dev;
78 struct p9_client *client;
81 struct xen_9pfs_dataring *rings;
84 static LIST_HEAD(xen_9pfs_devs);
85 static DEFINE_RWLOCK(xen_9pfs_lock);
87 /* We don't currently allow canceling of requests */
88 static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req)
93 static int p9_xen_create(struct p9_client *client, const char *addr, char *args)
95 struct xen_9pfs_front_priv *priv;
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);
108 read_unlock(&xen_9pfs_lock);
112 static void p9_xen_close(struct p9_client *client)
114 struct xen_9pfs_front_priv *priv;
116 read_lock(&xen_9pfs_lock);
117 list_for_each_entry(priv, &xen_9pfs_devs, list) {
118 if (priv->client == client) {
120 read_unlock(&xen_9pfs_lock);
124 read_unlock(&xen_9pfs_lock);
127 static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size)
131 cons = ring->intf->out_cons;
132 prod = ring->intf->out_prod;
135 return XEN_9PFS_RING_SIZE(ring) -
136 xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) >= size;
139 static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
141 struct xen_9pfs_front_priv *priv;
142 RING_IDX cons, prod, masked_cons, masked_prod;
144 u32 size = p9_req->tc.size;
145 struct xen_9pfs_dataring *ring;
148 read_lock(&xen_9pfs_lock);
149 list_for_each_entry(priv, &xen_9pfs_devs, list) {
150 if (priv->client == client)
153 read_unlock(&xen_9pfs_lock);
154 if (list_entry_is_head(priv, &xen_9pfs_devs, list))
157 num = p9_req->tc.tag % priv->num_rings;
158 ring = &priv->rings[num];
161 while (wait_event_killable(ring->wq,
162 p9_xen_write_todo(ring, size)) != 0)
165 spin_lock_irqsave(&ring->lock, flags);
166 cons = ring->intf->out_cons;
167 prod = ring->intf->out_prod;
170 if (XEN_9PFS_RING_SIZE(ring) -
171 xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) < size) {
172 spin_unlock_irqrestore(&ring->lock, flags);
176 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE(ring));
177 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring));
179 xen_9pfs_write_packet(ring->data.out, p9_req->tc.sdata, size,
180 &masked_prod, masked_cons,
181 XEN_9PFS_RING_SIZE(ring));
183 p9_req->status = REQ_STATUS_SENT;
184 virt_wmb(); /* write ring before updating pointer */
186 ring->intf->out_prod = prod;
187 spin_unlock_irqrestore(&ring->lock, flags);
188 notify_remote_via_irq(ring->irq);
189 p9_req_put(client, p9_req);
194 static void p9_xen_response(struct work_struct *work)
196 struct xen_9pfs_front_priv *priv;
197 struct xen_9pfs_dataring *ring;
198 RING_IDX cons, prod, masked_cons, masked_prod;
199 struct xen_9pfs_header h;
200 struct p9_req_t *req;
203 ring = container_of(work, struct xen_9pfs_dataring, work);
207 cons = ring->intf->in_cons;
208 prod = ring->intf->in_prod;
211 if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) <
213 notify_remote_via_irq(ring->irq);
217 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE(ring));
218 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring));
220 /* First, read just the header */
221 xen_9pfs_read_packet(&h, ring->data.in, sizeof(h),
222 masked_prod, &masked_cons,
223 XEN_9PFS_RING_SIZE(ring));
225 req = p9_tag_lookup(priv->client, h.tag);
226 if (!req || req->status != REQ_STATUS_SENT) {
227 dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag);
230 ring->intf->in_cons = cons;
234 if (h.size > req->rc.capacity) {
235 dev_warn(&priv->dev->dev,
236 "requested packet size too big: %d for tag %d with capacity %zd\n",
237 h.size, h.tag, req->rc.capacity);
238 req->status = REQ_STATUS_ERROR;
242 memcpy(&req->rc, &h, sizeof(h));
245 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring));
246 /* Then, read the whole packet (including the header) */
247 xen_9pfs_read_packet(req->rc.sdata, ring->data.in, h.size,
248 masked_prod, &masked_cons,
249 XEN_9PFS_RING_SIZE(ring));
254 ring->intf->in_cons = cons;
256 status = (req->status != REQ_STATUS_ERROR) ?
257 REQ_STATUS_RCVD : REQ_STATUS_ERROR;
259 p9_client_cb(priv->client, req, status);
263 static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r)
265 struct xen_9pfs_dataring *ring = r;
267 if (!ring || !ring->priv->client) {
268 /* ignore spurious interrupt */
272 wake_up_interruptible(&ring->wq);
273 schedule_work(&ring->work);
278 static struct p9_trans_module p9_xen_trans = {
280 .maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT - 2),
282 .create = p9_xen_create,
283 .close = p9_xen_close,
284 .request = p9_xen_request,
285 .cancel = p9_xen_cancel,
286 .owner = THIS_MODULE,
289 static const struct xenbus_device_id xen_9pfs_front_ids[] = {
294 static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
298 write_lock(&xen_9pfs_lock);
299 list_del(&priv->list);
300 write_unlock(&xen_9pfs_lock);
302 for (i = 0; i < priv->num_rings; i++) {
303 struct xen_9pfs_dataring *ring = &priv->rings[i];
305 cancel_work_sync(&ring->work);
307 if (!priv->rings[i].intf)
309 if (priv->rings[i].irq > 0)
310 unbind_from_irqhandler(priv->rings[i].irq, priv->dev);
311 if (priv->rings[i].data.in) {
313 j < (1 << priv->rings[i].intf->ring_order);
317 ref = priv->rings[i].intf->ref[j];
318 gnttab_end_foreign_access(ref, 0, 0);
320 free_pages_exact(priv->rings[i].data.in,
321 1UL << (priv->rings[i].intf->ring_order +
324 gnttab_end_foreign_access(priv->rings[i].ref, 0, 0);
325 free_page((unsigned long)priv->rings[i].intf);
332 static int xen_9pfs_front_remove(struct xenbus_device *dev)
334 struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
336 dev_set_drvdata(&dev->dev, NULL);
337 xen_9pfs_front_free(priv);
341 static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
342 struct xen_9pfs_dataring *ring,
349 init_waitqueue_head(&ring->wq);
350 spin_lock_init(&ring->lock);
351 INIT_WORK(&ring->work, p9_xen_response);
353 ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL);
356 ret = gnttab_grant_foreign_access(dev->otherend_id,
357 virt_to_gfn(ring->intf), 0);
361 bytes = alloc_pages_exact(1UL << (order + XEN_PAGE_SHIFT),
362 GFP_KERNEL | __GFP_ZERO);
367 for (; i < (1 << order); i++) {
368 ret = gnttab_grant_foreign_access(
369 dev->otherend_id, virt_to_gfn(bytes) + i, 0);
372 ring->intf->ref[i] = ret;
374 ring->intf->ring_order = order;
375 ring->data.in = bytes;
376 ring->data.out = bytes + XEN_FLEX_RING_SIZE(order);
378 ret = xenbus_alloc_evtchn(dev, &ring->evtchn);
381 ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
382 xen_9pfs_front_event_handler,
383 0, "xen_9pfs-frontend", ring);
387 xenbus_free_evtchn(dev, ring->evtchn);
391 for (i--; i >= 0; i--)
392 gnttab_end_foreign_access(ring->intf->ref[i], 0, 0);
393 free_pages_exact(bytes, 1UL << (order + XEN_PAGE_SHIFT));
395 gnttab_end_foreign_access(ring->ref, 0, 0);
396 free_page((unsigned long)ring->intf);
400 static int xen_9pfs_front_init(struct xenbus_device *dev)
403 struct xenbus_transaction xbt;
404 struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
406 unsigned int max_rings, max_ring_order, len = 0;
408 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
409 if (IS_ERR(versions))
410 return PTR_ERR(versions);
411 for (v = versions; *v; v++) {
412 if (simple_strtoul(v, &v, 10) == 1) {
422 max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0);
423 if (max_rings < XEN_9PFS_NUM_RINGS)
425 max_ring_order = xenbus_read_unsigned(dev->otherend,
426 "max-ring-page-order", 0);
427 if (max_ring_order > XEN_9PFS_RING_ORDER)
428 max_ring_order = XEN_9PFS_RING_ORDER;
429 if (p9_xen_trans.maxsize > XEN_FLEX_RING_SIZE(max_ring_order))
430 p9_xen_trans.maxsize = XEN_FLEX_RING_SIZE(max_ring_order) / 2;
432 priv->num_rings = XEN_9PFS_NUM_RINGS;
433 priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings),
440 for (i = 0; i < priv->num_rings; i++) {
441 priv->rings[i].priv = priv;
442 ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i],
449 ret = xenbus_transaction_start(&xbt);
451 xenbus_dev_fatal(dev, ret, "starting transaction");
454 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
457 ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u",
461 for (i = 0; i < priv->num_rings; i++) {
464 BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9);
465 sprintf(str, "ring-ref%d", i);
466 ret = xenbus_printf(xbt, dev->nodename, str, "%d",
471 sprintf(str, "event-channel-%d", i);
472 ret = xenbus_printf(xbt, dev->nodename, str, "%u",
473 priv->rings[i].evtchn);
477 priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL);
478 if (IS_ERR(priv->tag)) {
479 ret = PTR_ERR(priv->tag);
482 ret = xenbus_transaction_end(xbt, 0);
486 xenbus_dev_fatal(dev, ret, "completing transaction");
493 xenbus_transaction_end(xbt, 1);
494 xenbus_dev_fatal(dev, ret, "writing xenstore");
496 xen_9pfs_front_free(priv);
500 static int xen_9pfs_front_probe(struct xenbus_device *dev,
501 const struct xenbus_device_id *id)
503 struct xen_9pfs_front_priv *priv = NULL;
505 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
510 dev_set_drvdata(&dev->dev, priv);
512 write_lock(&xen_9pfs_lock);
513 list_add_tail(&priv->list, &xen_9pfs_devs);
514 write_unlock(&xen_9pfs_lock);
519 static int xen_9pfs_front_resume(struct xenbus_device *dev)
521 dev_warn(&dev->dev, "suspend/resume unsupported\n");
525 static void xen_9pfs_front_changed(struct xenbus_device *dev,
526 enum xenbus_state backend_state)
528 switch (backend_state) {
529 case XenbusStateReconfiguring:
530 case XenbusStateReconfigured:
531 case XenbusStateInitialising:
532 case XenbusStateInitialised:
533 case XenbusStateUnknown:
536 case XenbusStateInitWait:
537 if (!xen_9pfs_front_init(dev))
538 xenbus_switch_state(dev, XenbusStateInitialised);
541 case XenbusStateConnected:
542 xenbus_switch_state(dev, XenbusStateConnected);
545 case XenbusStateClosed:
546 if (dev->state == XenbusStateClosed)
548 fallthrough; /* Missed the backend's CLOSING state */
549 case XenbusStateClosing:
550 xenbus_frontend_closed(dev);
555 static struct xenbus_driver xen_9pfs_front_driver = {
556 .ids = xen_9pfs_front_ids,
557 .probe = xen_9pfs_front_probe,
558 .remove = xen_9pfs_front_remove,
559 .resume = xen_9pfs_front_resume,
560 .otherend_changed = xen_9pfs_front_changed,
563 static int p9_trans_xen_init(void)
570 pr_info("Initialising Xen transport for 9pfs\n");
572 v9fs_register_trans(&p9_xen_trans);
573 rc = xenbus_register_frontend(&xen_9pfs_front_driver);
575 v9fs_unregister_trans(&p9_xen_trans);
579 module_init(p9_trans_xen_init);
581 static void p9_trans_xen_exit(void)
583 v9fs_unregister_trans(&p9_xen_trans);
584 return xenbus_unregister_driver(&xen_9pfs_front_driver);
586 module_exit(p9_trans_xen_exit);
588 MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>");
589 MODULE_DESCRIPTION("Xen Transport for 9P");
590 MODULE_LICENSE("GPL");