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 <linux/rwlock.h>
42 #include <net/9p/9p.h>
43 #include <net/9p/client.h>
44 #include <net/9p/transport.h>
46 #define XEN_9PFS_NUM_RINGS 2
47 #define XEN_9PFS_RING_ORDER 6
48 #define XEN_9PFS_RING_SIZE XEN_FLEX_RING_SIZE(XEN_9PFS_RING_ORDER)
50 struct xen_9pfs_header {
55 /* uint8_t sdata[]; */
56 } __attribute__((packed));
58 /* One per ring, more than one per 9pfs share */
59 struct xen_9pfs_dataring {
60 struct xen_9pfs_front_priv *priv;
62 struct xen_9pfs_data_intf *intf;
66 /* protect a ring from concurrent accesses */
69 struct xen_9pfs_data data;
71 struct work_struct work;
74 /* One per 9pfs share */
75 struct xen_9pfs_front_priv {
76 struct list_head list;
77 struct xenbus_device *dev;
79 struct p9_client *client;
82 struct xen_9pfs_dataring *rings;
85 static LIST_HEAD(xen_9pfs_devs);
86 static DEFINE_RWLOCK(xen_9pfs_lock);
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)
98 static void p9_xen_close(struct p9_client *client)
102 static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
107 static void p9_xen_response(struct work_struct *work)
111 static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r)
113 struct xen_9pfs_dataring *ring = r;
115 if (!ring || !ring->priv->client) {
116 /* ignore spurious interrupt */
120 wake_up_interruptible(&ring->wq);
121 schedule_work(&ring->work);
126 static struct p9_trans_module p9_xen_trans = {
128 .maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT),
130 .create = p9_xen_create,
131 .close = p9_xen_close,
132 .request = p9_xen_request,
133 .cancel = p9_xen_cancel,
134 .owner = THIS_MODULE,
137 static const struct xenbus_device_id xen_9pfs_front_ids[] = {
142 static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
146 write_lock(&xen_9pfs_lock);
147 list_del(&priv->list);
148 write_unlock(&xen_9pfs_lock);
150 for (i = 0; i < priv->num_rings; i++) {
151 if (!priv->rings[i].intf)
153 if (priv->rings[i].irq > 0)
154 unbind_from_irqhandler(priv->rings[i].irq, priv->dev);
155 if (priv->rings[i].data.in) {
156 for (j = 0; j < (1 << XEN_9PFS_RING_ORDER); j++) {
159 ref = priv->rings[i].intf->ref[j];
160 gnttab_end_foreign_access(ref, 0, 0);
162 free_pages((unsigned long)priv->rings[i].data.in,
163 XEN_9PFS_RING_ORDER -
164 (PAGE_SHIFT - XEN_PAGE_SHIFT));
166 gnttab_end_foreign_access(priv->rings[i].ref, 0, 0);
167 free_page((unsigned long)priv->rings[i].intf);
174 static int xen_9pfs_front_remove(struct xenbus_device *dev)
176 struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
178 dev_set_drvdata(&dev->dev, NULL);
179 xen_9pfs_front_free(priv);
183 static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
184 struct xen_9pfs_dataring *ring)
190 init_waitqueue_head(&ring->wq);
191 spin_lock_init(&ring->lock);
192 INIT_WORK(&ring->work, p9_xen_response);
194 ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL);
197 ret = gnttab_grant_foreign_access(dev->otherend_id,
198 virt_to_gfn(ring->intf), 0);
202 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
203 XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT));
208 for (; i < (1 << XEN_9PFS_RING_ORDER); i++) {
209 ret = gnttab_grant_foreign_access(
210 dev->otherend_id, virt_to_gfn(bytes) + i, 0);
213 ring->intf->ref[i] = ret;
215 ring->intf->ring_order = XEN_9PFS_RING_ORDER;
216 ring->data.in = bytes;
217 ring->data.out = bytes + XEN_9PFS_RING_SIZE;
219 ret = xenbus_alloc_evtchn(dev, &ring->evtchn);
222 ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
223 xen_9pfs_front_event_handler,
224 0, "xen_9pfs-frontend", ring);
228 xenbus_free_evtchn(dev, ring->evtchn);
232 for (i--; i >= 0; i--)
233 gnttab_end_foreign_access(ring->intf->ref[i], 0, 0);
234 free_pages((unsigned long)bytes,
235 XEN_9PFS_RING_ORDER -
236 (PAGE_SHIFT - XEN_PAGE_SHIFT));
238 gnttab_end_foreign_access(ring->ref, 0, 0);
239 free_page((unsigned long)ring->intf);
243 static int xen_9pfs_front_probe(struct xenbus_device *dev,
244 const struct xenbus_device_id *id)
247 struct xenbus_transaction xbt;
248 struct xen_9pfs_front_priv *priv = NULL;
250 unsigned int max_rings, max_ring_order, len;
252 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
255 if (strcmp(versions, "1")) {
260 max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0);
261 if (max_rings < XEN_9PFS_NUM_RINGS)
263 max_ring_order = xenbus_read_unsigned(dev->otherend,
264 "max-ring-page-order", 0);
265 if (max_ring_order < XEN_9PFS_RING_ORDER)
268 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
273 priv->num_rings = XEN_9PFS_NUM_RINGS;
274 priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings),
281 for (i = 0; i < priv->num_rings; i++) {
282 priv->rings[i].priv = priv;
283 ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i]);
289 ret = xenbus_transaction_start(&xbt);
291 xenbus_dev_fatal(dev, ret, "starting transaction");
294 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
297 ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u",
301 for (i = 0; i < priv->num_rings; i++) {
304 BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9);
305 sprintf(str, "ring-ref%u", i);
306 ret = xenbus_printf(xbt, dev->nodename, str, "%d",
311 sprintf(str, "event-channel-%u", i);
312 ret = xenbus_printf(xbt, dev->nodename, str, "%u",
313 priv->rings[i].evtchn);
317 priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL);
322 ret = xenbus_transaction_end(xbt, 0);
326 xenbus_dev_fatal(dev, ret, "completing transaction");
330 write_lock(&xen_9pfs_lock);
331 list_add_tail(&priv->list, &xen_9pfs_devs);
332 write_unlock(&xen_9pfs_lock);
333 dev_set_drvdata(&dev->dev, priv);
334 xenbus_switch_state(dev, XenbusStateInitialised);
339 xenbus_transaction_end(xbt, 1);
340 xenbus_dev_fatal(dev, ret, "writing xenstore");
342 dev_set_drvdata(&dev->dev, NULL);
343 xen_9pfs_front_free(priv);
347 static int xen_9pfs_front_resume(struct xenbus_device *dev)
349 dev_warn(&dev->dev, "suspsend/resume unsupported\n");
353 static void xen_9pfs_front_changed(struct xenbus_device *dev,
354 enum xenbus_state backend_state)
356 switch (backend_state) {
357 case XenbusStateReconfiguring:
358 case XenbusStateReconfigured:
359 case XenbusStateInitialising:
360 case XenbusStateInitialised:
361 case XenbusStateUnknown:
364 case XenbusStateInitWait:
367 case XenbusStateConnected:
368 xenbus_switch_state(dev, XenbusStateConnected);
371 case XenbusStateClosed:
372 if (dev->state == XenbusStateClosed)
374 /* Missed the backend's CLOSING state -- fallthrough */
375 case XenbusStateClosing:
376 xenbus_frontend_closed(dev);
381 static struct xenbus_driver xen_9pfs_front_driver = {
382 .ids = xen_9pfs_front_ids,
383 .probe = xen_9pfs_front_probe,
384 .remove = xen_9pfs_front_remove,
385 .resume = xen_9pfs_front_resume,
386 .otherend_changed = xen_9pfs_front_changed,
389 int p9_trans_xen_init(void)
394 pr_info("Initialising Xen transport for 9pfs\n");
396 v9fs_register_trans(&p9_xen_trans);
397 return xenbus_register_frontend(&xen_9pfs_front_driver);
399 module_init(p9_trans_xen_init);
401 void p9_trans_xen_exit(void)
403 v9fs_unregister_trans(&p9_xen_trans);
404 return xenbus_unregister_driver(&xen_9pfs_front_driver);
406 module_exit(p9_trans_xen_exit);