1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/fs/9p/trans_xen
7 * Copyright (C) 2017 by Stefano Stabellini <stefano@aporeto.com>
10 #include <xen/events.h>
11 #include <xen/grant_table.h>
13 #include <xen/xenbus.h>
14 #include <xen/interface/io/9pfs.h>
16 #include <linux/module.h>
17 #include <linux/spinlock.h>
18 #include <net/9p/9p.h>
19 #include <net/9p/client.h>
20 #include <net/9p/transport.h>
22 #define XEN_9PFS_NUM_RINGS 2
23 #define XEN_9PFS_RING_ORDER 9
24 #define XEN_9PFS_RING_SIZE(ring) XEN_FLEX_RING_SIZE(ring->intf->ring_order)
26 struct xen_9pfs_header {
31 /* uint8_t sdata[]; */
32 } __attribute__((packed));
34 /* One per ring, more than one per 9pfs share */
35 struct xen_9pfs_dataring {
36 struct xen_9pfs_front_priv *priv;
38 struct xen_9pfs_data_intf *intf;
42 /* protect a ring from concurrent accesses */
45 struct xen_9pfs_data data;
47 struct work_struct work;
50 /* One per 9pfs share */
51 struct xen_9pfs_front_priv {
52 struct list_head list;
53 struct xenbus_device *dev;
55 struct p9_client *client;
58 struct xen_9pfs_dataring *rings;
61 static LIST_HEAD(xen_9pfs_devs);
62 static DEFINE_RWLOCK(xen_9pfs_lock);
64 /* We don't currently allow canceling of requests */
65 static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req)
70 static int p9_xen_create(struct p9_client *client, const char *addr, char *args)
72 struct xen_9pfs_front_priv *priv;
77 read_lock(&xen_9pfs_lock);
78 list_for_each_entry(priv, &xen_9pfs_devs, list) {
79 if (!strcmp(priv->tag, addr)) {
80 priv->client = client;
81 read_unlock(&xen_9pfs_lock);
85 read_unlock(&xen_9pfs_lock);
89 static void p9_xen_close(struct p9_client *client)
91 struct xen_9pfs_front_priv *priv;
93 read_lock(&xen_9pfs_lock);
94 list_for_each_entry(priv, &xen_9pfs_devs, list) {
95 if (priv->client == client) {
97 read_unlock(&xen_9pfs_lock);
101 read_unlock(&xen_9pfs_lock);
104 static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size)
108 cons = ring->intf->out_cons;
109 prod = ring->intf->out_prod;
112 return XEN_9PFS_RING_SIZE(ring) -
113 xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) >= size;
116 static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
118 struct xen_9pfs_front_priv *priv;
119 RING_IDX cons, prod, masked_cons, masked_prod;
121 u32 size = p9_req->tc.size;
122 struct xen_9pfs_dataring *ring;
125 read_lock(&xen_9pfs_lock);
126 list_for_each_entry(priv, &xen_9pfs_devs, list) {
127 if (priv->client == client)
130 read_unlock(&xen_9pfs_lock);
131 if (list_entry_is_head(priv, &xen_9pfs_devs, list))
134 num = p9_req->tc.tag % priv->num_rings;
135 ring = &priv->rings[num];
138 while (wait_event_killable(ring->wq,
139 p9_xen_write_todo(ring, size)) != 0)
142 spin_lock_irqsave(&ring->lock, flags);
143 cons = ring->intf->out_cons;
144 prod = ring->intf->out_prod;
147 if (XEN_9PFS_RING_SIZE(ring) -
148 xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) < size) {
149 spin_unlock_irqrestore(&ring->lock, flags);
153 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE(ring));
154 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring));
156 xen_9pfs_write_packet(ring->data.out, p9_req->tc.sdata, size,
157 &masked_prod, masked_cons,
158 XEN_9PFS_RING_SIZE(ring));
160 WRITE_ONCE(p9_req->status, REQ_STATUS_SENT);
161 virt_wmb(); /* write ring before updating pointer */
163 ring->intf->out_prod = prod;
164 spin_unlock_irqrestore(&ring->lock, flags);
165 notify_remote_via_irq(ring->irq);
166 p9_req_put(client, p9_req);
171 static void p9_xen_response(struct work_struct *work)
173 struct xen_9pfs_front_priv *priv;
174 struct xen_9pfs_dataring *ring;
175 RING_IDX cons, prod, masked_cons, masked_prod;
176 struct xen_9pfs_header h;
177 struct p9_req_t *req;
180 ring = container_of(work, struct xen_9pfs_dataring, work);
184 cons = ring->intf->in_cons;
185 prod = ring->intf->in_prod;
188 if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) <
190 notify_remote_via_irq(ring->irq);
194 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE(ring));
195 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring));
197 /* First, read just the header */
198 xen_9pfs_read_packet(&h, ring->data.in, sizeof(h),
199 masked_prod, &masked_cons,
200 XEN_9PFS_RING_SIZE(ring));
202 req = p9_tag_lookup(priv->client, h.tag);
203 if (!req || req->status != REQ_STATUS_SENT) {
204 dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag);
207 ring->intf->in_cons = cons;
211 if (h.size > req->rc.capacity) {
212 dev_warn(&priv->dev->dev,
213 "requested packet size too big: %d for tag %d with capacity %zd\n",
214 h.size, h.tag, req->rc.capacity);
215 WRITE_ONCE(req->status, REQ_STATUS_ERROR);
219 req->rc.size = h.size;
224 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring));
225 /* Then, read the whole packet (including the header) */
226 xen_9pfs_read_packet(req->rc.sdata, ring->data.in, h.size,
227 masked_prod, &masked_cons,
228 XEN_9PFS_RING_SIZE(ring));
233 ring->intf->in_cons = cons;
235 status = (req->status != REQ_STATUS_ERROR) ?
236 REQ_STATUS_RCVD : REQ_STATUS_ERROR;
238 p9_client_cb(priv->client, req, status);
242 static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r)
244 struct xen_9pfs_dataring *ring = r;
246 if (!ring || !ring->priv->client) {
247 /* ignore spurious interrupt */
251 wake_up_interruptible(&ring->wq);
252 schedule_work(&ring->work);
257 static struct p9_trans_module p9_xen_trans = {
259 .maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT - 2),
260 .pooled_rbuffers = false,
262 .create = p9_xen_create,
263 .close = p9_xen_close,
264 .request = p9_xen_request,
265 .cancel = p9_xen_cancel,
266 .owner = THIS_MODULE,
269 static const struct xenbus_device_id xen_9pfs_front_ids[] = {
274 static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
278 write_lock(&xen_9pfs_lock);
279 list_del(&priv->list);
280 write_unlock(&xen_9pfs_lock);
282 for (i = 0; i < priv->num_rings; i++) {
283 if (!priv->rings[i].intf)
285 if (priv->rings[i].irq > 0)
286 unbind_from_irqhandler(priv->rings[i].irq, priv->dev);
287 if (priv->rings[i].data.in) {
289 j < (1 << priv->rings[i].intf->ring_order);
293 ref = priv->rings[i].intf->ref[j];
294 gnttab_end_foreign_access(ref, NULL);
296 free_pages_exact(priv->rings[i].data.in,
297 1UL << (priv->rings[i].intf->ring_order +
300 gnttab_end_foreign_access(priv->rings[i].ref, NULL);
301 free_page((unsigned long)priv->rings[i].intf);
308 static void xen_9pfs_front_remove(struct xenbus_device *dev)
310 struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
312 dev_set_drvdata(&dev->dev, NULL);
313 xen_9pfs_front_free(priv);
316 static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
317 struct xen_9pfs_dataring *ring,
324 init_waitqueue_head(&ring->wq);
325 spin_lock_init(&ring->lock);
326 INIT_WORK(&ring->work, p9_xen_response);
328 ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL);
331 ret = gnttab_grant_foreign_access(dev->otherend_id,
332 virt_to_gfn(ring->intf), 0);
336 bytes = alloc_pages_exact(1UL << (order + XEN_PAGE_SHIFT),
337 GFP_KERNEL | __GFP_ZERO);
342 for (; i < (1 << order); i++) {
343 ret = gnttab_grant_foreign_access(
344 dev->otherend_id, virt_to_gfn(bytes) + i, 0);
347 ring->intf->ref[i] = ret;
349 ring->intf->ring_order = order;
350 ring->data.in = bytes;
351 ring->data.out = bytes + XEN_FLEX_RING_SIZE(order);
353 ret = xenbus_alloc_evtchn(dev, &ring->evtchn);
356 ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
357 xen_9pfs_front_event_handler,
358 0, "xen_9pfs-frontend", ring);
362 xenbus_free_evtchn(dev, ring->evtchn);
366 for (i--; i >= 0; i--)
367 gnttab_end_foreign_access(ring->intf->ref[i], NULL);
368 free_pages_exact(bytes, 1UL << (order + XEN_PAGE_SHIFT));
370 gnttab_end_foreign_access(ring->ref, NULL);
371 free_page((unsigned long)ring->intf);
375 static int xen_9pfs_front_probe(struct xenbus_device *dev,
376 const struct xenbus_device_id *id)
379 struct xenbus_transaction xbt;
380 struct xen_9pfs_front_priv *priv = NULL;
382 unsigned int max_rings, max_ring_order, len = 0;
384 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
385 if (IS_ERR(versions))
386 return PTR_ERR(versions);
387 if (strcmp(versions, "1")) {
392 max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0);
393 if (max_rings < XEN_9PFS_NUM_RINGS)
395 max_ring_order = xenbus_read_unsigned(dev->otherend,
396 "max-ring-page-order", 0);
397 if (max_ring_order > XEN_9PFS_RING_ORDER)
398 max_ring_order = XEN_9PFS_RING_ORDER;
399 if (p9_xen_trans.maxsize > XEN_FLEX_RING_SIZE(max_ring_order))
400 p9_xen_trans.maxsize = XEN_FLEX_RING_SIZE(max_ring_order) / 2;
402 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
407 priv->num_rings = XEN_9PFS_NUM_RINGS;
408 priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings),
415 for (i = 0; i < priv->num_rings; i++) {
416 priv->rings[i].priv = priv;
417 ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i],
424 ret = xenbus_transaction_start(&xbt);
426 xenbus_dev_fatal(dev, ret, "starting transaction");
429 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
432 ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u",
436 for (i = 0; i < priv->num_rings; i++) {
439 BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9);
440 sprintf(str, "ring-ref%d", i);
441 ret = xenbus_printf(xbt, dev->nodename, str, "%d",
446 sprintf(str, "event-channel-%d", i);
447 ret = xenbus_printf(xbt, dev->nodename, str, "%u",
448 priv->rings[i].evtchn);
452 priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL);
453 if (IS_ERR(priv->tag)) {
454 ret = PTR_ERR(priv->tag);
457 ret = xenbus_transaction_end(xbt, 0);
461 xenbus_dev_fatal(dev, ret, "completing transaction");
465 write_lock(&xen_9pfs_lock);
466 list_add_tail(&priv->list, &xen_9pfs_devs);
467 write_unlock(&xen_9pfs_lock);
468 dev_set_drvdata(&dev->dev, priv);
469 xenbus_switch_state(dev, XenbusStateInitialised);
474 xenbus_transaction_end(xbt, 1);
475 xenbus_dev_fatal(dev, ret, "writing xenstore");
477 dev_set_drvdata(&dev->dev, NULL);
478 xen_9pfs_front_free(priv);
482 static int xen_9pfs_front_resume(struct xenbus_device *dev)
484 dev_warn(&dev->dev, "suspend/resume unsupported\n");
488 static void xen_9pfs_front_changed(struct xenbus_device *dev,
489 enum xenbus_state backend_state)
491 switch (backend_state) {
492 case XenbusStateReconfiguring:
493 case XenbusStateReconfigured:
494 case XenbusStateInitialising:
495 case XenbusStateInitialised:
496 case XenbusStateUnknown:
499 case XenbusStateInitWait:
502 case XenbusStateConnected:
503 xenbus_switch_state(dev, XenbusStateConnected);
506 case XenbusStateClosed:
507 if (dev->state == XenbusStateClosed)
509 fallthrough; /* Missed the backend's CLOSING state */
510 case XenbusStateClosing:
511 xenbus_frontend_closed(dev);
516 static struct xenbus_driver xen_9pfs_front_driver = {
517 .ids = xen_9pfs_front_ids,
518 .probe = xen_9pfs_front_probe,
519 .remove = xen_9pfs_front_remove,
520 .resume = xen_9pfs_front_resume,
521 .otherend_changed = xen_9pfs_front_changed,
524 static int __init p9_trans_xen_init(void)
531 pr_info("Initialising Xen transport for 9pfs\n");
533 v9fs_register_trans(&p9_xen_trans);
534 rc = xenbus_register_frontend(&xen_9pfs_front_driver);
536 v9fs_unregister_trans(&p9_xen_trans);
540 module_init(p9_trans_xen_init);
541 MODULE_ALIAS_9P("xen");
543 static void __exit p9_trans_xen_exit(void)
545 v9fs_unregister_trans(&p9_xen_trans);
546 return xenbus_unregister_driver(&xen_9pfs_front_driver);
548 module_exit(p9_trans_xen_exit);
550 MODULE_ALIAS("xen:9pfs");
551 MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>");
552 MODULE_DESCRIPTION("Xen Transport for 9P");
553 MODULE_LICENSE("GPL");