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[mirror_ubuntu-bionic-kernel.git] / drivers / xen / pvcalls-front.c
1 /*
2 * (c) 2017 Stefano Stabellini <stefano@aporeto.com>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 */
14
15 #include <linux/module.h>
16 #include <linux/net.h>
17 #include <linux/socket.h>
18
19 #include <net/sock.h>
20
21 #include <xen/events.h>
22 #include <xen/grant_table.h>
23 #include <xen/xen.h>
24 #include <xen/xenbus.h>
25 #include <xen/interface/io/pvcalls.h>
26
27 #include "pvcalls-front.h"
28
29 #define PVCALLS_INVALID_ID UINT_MAX
30 #define PVCALLS_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
31 #define PVCALLS_NR_RSP_PER_RING __CONST_RING_SIZE(xen_pvcalls, XEN_PAGE_SIZE)
32 #define PVCALLS_FRONT_MAX_SPIN 5000
33
34 struct pvcalls_bedata {
35 struct xen_pvcalls_front_ring ring;
36 grant_ref_t ref;
37 int irq;
38
39 struct list_head socket_mappings;
40 spinlock_t socket_lock;
41
42 wait_queue_head_t inflight_req;
43 struct xen_pvcalls_response rsp[PVCALLS_NR_RSP_PER_RING];
44 };
45 /* Only one front/back connection supported. */
46 static struct xenbus_device *pvcalls_front_dev;
47 static atomic_t pvcalls_refcount;
48
49 /* first increment refcount, then proceed */
50 #define pvcalls_enter() { \
51 atomic_inc(&pvcalls_refcount); \
52 }
53
54 /* first complete other operations, then decrement refcount */
55 #define pvcalls_exit() { \
56 atomic_dec(&pvcalls_refcount); \
57 }
58
59 struct sock_mapping {
60 bool active_socket;
61 struct list_head list;
62 struct socket *sock;
63 union {
64 struct {
65 int irq;
66 grant_ref_t ref;
67 struct pvcalls_data_intf *ring;
68 struct pvcalls_data data;
69 struct mutex in_mutex;
70 struct mutex out_mutex;
71
72 wait_queue_head_t inflight_conn_req;
73 } active;
74 struct {
75 /* Socket status */
76 #define PVCALLS_STATUS_UNINITALIZED 0
77 #define PVCALLS_STATUS_BIND 1
78 #define PVCALLS_STATUS_LISTEN 2
79 uint8_t status;
80 /*
81 * Internal state-machine flags.
82 * Only one accept operation can be inflight for a socket.
83 * Only one poll operation can be inflight for a given socket.
84 */
85 #define PVCALLS_FLAG_ACCEPT_INFLIGHT 0
86 #define PVCALLS_FLAG_POLL_INFLIGHT 1
87 #define PVCALLS_FLAG_POLL_RET 2
88 uint8_t flags;
89 uint32_t inflight_req_id;
90 struct sock_mapping *accept_map;
91 wait_queue_head_t inflight_accept_req;
92 } passive;
93 };
94 };
95
96 static inline int get_request(struct pvcalls_bedata *bedata, int *req_id)
97 {
98 *req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1);
99 if (RING_FULL(&bedata->ring) ||
100 bedata->rsp[*req_id].req_id != PVCALLS_INVALID_ID)
101 return -EAGAIN;
102 return 0;
103 }
104
105 static bool pvcalls_front_write_todo(struct sock_mapping *map)
106 {
107 struct pvcalls_data_intf *intf = map->active.ring;
108 RING_IDX cons, prod, size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
109 int32_t error;
110
111 error = intf->out_error;
112 if (error == -ENOTCONN)
113 return false;
114 if (error != 0)
115 return true;
116
117 cons = intf->out_cons;
118 prod = intf->out_prod;
119 return !!(size - pvcalls_queued(prod, cons, size));
120 }
121
122 static bool pvcalls_front_read_todo(struct sock_mapping *map)
123 {
124 struct pvcalls_data_intf *intf = map->active.ring;
125 RING_IDX cons, prod;
126 int32_t error;
127
128 cons = intf->in_cons;
129 prod = intf->in_prod;
130 error = intf->in_error;
131 return (error != 0 ||
132 pvcalls_queued(prod, cons,
133 XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER)) != 0);
134 }
135
136 static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
137 {
138 struct xenbus_device *dev = dev_id;
139 struct pvcalls_bedata *bedata;
140 struct xen_pvcalls_response *rsp;
141 uint8_t *src, *dst;
142 int req_id = 0, more = 0, done = 0;
143
144 if (dev == NULL)
145 return IRQ_HANDLED;
146
147 pvcalls_enter();
148 bedata = dev_get_drvdata(&dev->dev);
149 if (bedata == NULL) {
150 pvcalls_exit();
151 return IRQ_HANDLED;
152 }
153
154 again:
155 while (RING_HAS_UNCONSUMED_RESPONSES(&bedata->ring)) {
156 rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons);
157
158 req_id = rsp->req_id;
159 if (rsp->cmd == PVCALLS_POLL) {
160 struct sock_mapping *map = (struct sock_mapping *)(uintptr_t)
161 rsp->u.poll.id;
162
163 clear_bit(PVCALLS_FLAG_POLL_INFLIGHT,
164 (void *)&map->passive.flags);
165 /*
166 * clear INFLIGHT, then set RET. It pairs with
167 * the checks at the beginning of
168 * pvcalls_front_poll_passive.
169 */
170 smp_wmb();
171 set_bit(PVCALLS_FLAG_POLL_RET,
172 (void *)&map->passive.flags);
173 } else {
174 dst = (uint8_t *)&bedata->rsp[req_id] +
175 sizeof(rsp->req_id);
176 src = (uint8_t *)rsp + sizeof(rsp->req_id);
177 memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id));
178 /*
179 * First copy the rest of the data, then req_id. It is
180 * paired with the barrier when accessing bedata->rsp.
181 */
182 smp_wmb();
183 bedata->rsp[req_id].req_id = req_id;
184 }
185
186 done = 1;
187 bedata->ring.rsp_cons++;
188 }
189
190 RING_FINAL_CHECK_FOR_RESPONSES(&bedata->ring, more);
191 if (more)
192 goto again;
193 if (done)
194 wake_up(&bedata->inflight_req);
195 pvcalls_exit();
196 return IRQ_HANDLED;
197 }
198
199 static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
200 struct sock_mapping *map)
201 {
202 int i;
203
204 unbind_from_irqhandler(map->active.irq, map);
205
206 spin_lock(&bedata->socket_lock);
207 if (!list_empty(&map->list))
208 list_del_init(&map->list);
209 spin_unlock(&bedata->socket_lock);
210
211 for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
212 gnttab_end_foreign_access(map->active.ring->ref[i], 0, 0);
213 gnttab_end_foreign_access(map->active.ref, 0, 0);
214 free_page((unsigned long)map->active.ring);
215
216 kfree(map);
217 }
218
219 static irqreturn_t pvcalls_front_conn_handler(int irq, void *sock_map)
220 {
221 struct sock_mapping *map = sock_map;
222
223 if (map == NULL)
224 return IRQ_HANDLED;
225
226 wake_up_interruptible(&map->active.inflight_conn_req);
227
228 return IRQ_HANDLED;
229 }
230
231 int pvcalls_front_socket(struct socket *sock)
232 {
233 struct pvcalls_bedata *bedata;
234 struct sock_mapping *map = NULL;
235 struct xen_pvcalls_request *req;
236 int notify, req_id, ret;
237
238 /*
239 * PVCalls only supports domain AF_INET,
240 * type SOCK_STREAM and protocol 0 sockets for now.
241 *
242 * Check socket type here, AF_INET and protocol checks are done
243 * by the caller.
244 */
245 if (sock->type != SOCK_STREAM)
246 return -EOPNOTSUPP;
247
248 pvcalls_enter();
249 if (!pvcalls_front_dev) {
250 pvcalls_exit();
251 return -EACCES;
252 }
253 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
254
255 map = kzalloc(sizeof(*map), GFP_KERNEL);
256 if (map == NULL) {
257 pvcalls_exit();
258 return -ENOMEM;
259 }
260
261 spin_lock(&bedata->socket_lock);
262
263 ret = get_request(bedata, &req_id);
264 if (ret < 0) {
265 kfree(map);
266 spin_unlock(&bedata->socket_lock);
267 pvcalls_exit();
268 return ret;
269 }
270
271 /*
272 * sock->sk->sk_send_head is not used for ip sockets: reuse the
273 * field to store a pointer to the struct sock_mapping
274 * corresponding to the socket. This way, we can easily get the
275 * struct sock_mapping from the struct socket.
276 */
277 sock->sk->sk_send_head = (void *)map;
278 list_add_tail(&map->list, &bedata->socket_mappings);
279
280 req = RING_GET_REQUEST(&bedata->ring, req_id);
281 req->req_id = req_id;
282 req->cmd = PVCALLS_SOCKET;
283 req->u.socket.id = (uintptr_t) map;
284 req->u.socket.domain = AF_INET;
285 req->u.socket.type = SOCK_STREAM;
286 req->u.socket.protocol = IPPROTO_IP;
287
288 bedata->ring.req_prod_pvt++;
289 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
290 spin_unlock(&bedata->socket_lock);
291 if (notify)
292 notify_remote_via_irq(bedata->irq);
293
294 wait_event(bedata->inflight_req,
295 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
296
297 /* read req_id, then the content */
298 smp_rmb();
299 ret = bedata->rsp[req_id].ret;
300 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
301
302 pvcalls_exit();
303 return ret;
304 }
305
306 static int create_active(struct sock_mapping *map, int *evtchn)
307 {
308 void *bytes;
309 int ret = -ENOMEM, irq = -1, i;
310
311 *evtchn = -1;
312 init_waitqueue_head(&map->active.inflight_conn_req);
313
314 map->active.ring = (struct pvcalls_data_intf *)
315 __get_free_page(GFP_KERNEL | __GFP_ZERO);
316 if (map->active.ring == NULL)
317 goto out_error;
318 map->active.ring->ring_order = PVCALLS_RING_ORDER;
319 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
320 PVCALLS_RING_ORDER);
321 if (bytes == NULL)
322 goto out_error;
323 for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
324 map->active.ring->ref[i] = gnttab_grant_foreign_access(
325 pvcalls_front_dev->otherend_id,
326 pfn_to_gfn(virt_to_pfn(bytes) + i), 0);
327
328 map->active.ref = gnttab_grant_foreign_access(
329 pvcalls_front_dev->otherend_id,
330 pfn_to_gfn(virt_to_pfn((void *)map->active.ring)), 0);
331
332 map->active.data.in = bytes;
333 map->active.data.out = bytes +
334 XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
335
336 ret = xenbus_alloc_evtchn(pvcalls_front_dev, evtchn);
337 if (ret)
338 goto out_error;
339 irq = bind_evtchn_to_irqhandler(*evtchn, pvcalls_front_conn_handler,
340 0, "pvcalls-frontend", map);
341 if (irq < 0) {
342 ret = irq;
343 goto out_error;
344 }
345
346 map->active.irq = irq;
347 map->active_socket = true;
348 mutex_init(&map->active.in_mutex);
349 mutex_init(&map->active.out_mutex);
350
351 return 0;
352
353 out_error:
354 if (*evtchn >= 0)
355 xenbus_free_evtchn(pvcalls_front_dev, *evtchn);
356 kfree(map->active.data.in);
357 kfree(map->active.ring);
358 return ret;
359 }
360
361 int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
362 int addr_len, int flags)
363 {
364 struct pvcalls_bedata *bedata;
365 struct sock_mapping *map = NULL;
366 struct xen_pvcalls_request *req;
367 int notify, req_id, ret, evtchn;
368
369 if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
370 return -EOPNOTSUPP;
371
372 pvcalls_enter();
373 if (!pvcalls_front_dev) {
374 pvcalls_exit();
375 return -ENOTCONN;
376 }
377
378 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
379
380 map = (struct sock_mapping *)sock->sk->sk_send_head;
381 if (!map) {
382 pvcalls_exit();
383 return -ENOTSOCK;
384 }
385
386 spin_lock(&bedata->socket_lock);
387 ret = get_request(bedata, &req_id);
388 if (ret < 0) {
389 spin_unlock(&bedata->socket_lock);
390 pvcalls_exit();
391 return ret;
392 }
393 ret = create_active(map, &evtchn);
394 if (ret < 0) {
395 spin_unlock(&bedata->socket_lock);
396 pvcalls_exit();
397 return ret;
398 }
399
400 req = RING_GET_REQUEST(&bedata->ring, req_id);
401 req->req_id = req_id;
402 req->cmd = PVCALLS_CONNECT;
403 req->u.connect.id = (uintptr_t)map;
404 req->u.connect.len = addr_len;
405 req->u.connect.flags = flags;
406 req->u.connect.ref = map->active.ref;
407 req->u.connect.evtchn = evtchn;
408 memcpy(req->u.connect.addr, addr, sizeof(*addr));
409
410 map->sock = sock;
411
412 bedata->ring.req_prod_pvt++;
413 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
414 spin_unlock(&bedata->socket_lock);
415
416 if (notify)
417 notify_remote_via_irq(bedata->irq);
418
419 wait_event(bedata->inflight_req,
420 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
421
422 /* read req_id, then the content */
423 smp_rmb();
424 ret = bedata->rsp[req_id].ret;
425 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
426 pvcalls_exit();
427 return ret;
428 }
429
430 static int __write_ring(struct pvcalls_data_intf *intf,
431 struct pvcalls_data *data,
432 struct iov_iter *msg_iter,
433 int len)
434 {
435 RING_IDX cons, prod, size, masked_prod, masked_cons;
436 RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
437 int32_t error;
438
439 error = intf->out_error;
440 if (error < 0)
441 return error;
442 cons = intf->out_cons;
443 prod = intf->out_prod;
444 /* read indexes before continuing */
445 virt_mb();
446
447 size = pvcalls_queued(prod, cons, array_size);
448 if (size >= array_size)
449 return -EINVAL;
450 if (len > array_size - size)
451 len = array_size - size;
452
453 masked_prod = pvcalls_mask(prod, array_size);
454 masked_cons = pvcalls_mask(cons, array_size);
455
456 if (masked_prod < masked_cons) {
457 len = copy_from_iter(data->out + masked_prod, len, msg_iter);
458 } else {
459 if (len > array_size - masked_prod) {
460 int ret = copy_from_iter(data->out + masked_prod,
461 array_size - masked_prod, msg_iter);
462 if (ret != array_size - masked_prod) {
463 len = ret;
464 goto out;
465 }
466 len = ret + copy_from_iter(data->out, len - ret, msg_iter);
467 } else {
468 len = copy_from_iter(data->out + masked_prod, len, msg_iter);
469 }
470 }
471 out:
472 /* write to ring before updating pointer */
473 virt_wmb();
474 intf->out_prod += len;
475
476 return len;
477 }
478
479 int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg,
480 size_t len)
481 {
482 struct pvcalls_bedata *bedata;
483 struct sock_mapping *map;
484 int sent, tot_sent = 0;
485 int count = 0, flags;
486
487 flags = msg->msg_flags;
488 if (flags & (MSG_CONFIRM|MSG_DONTROUTE|MSG_EOR|MSG_OOB))
489 return -EOPNOTSUPP;
490
491 pvcalls_enter();
492 if (!pvcalls_front_dev) {
493 pvcalls_exit();
494 return -ENOTCONN;
495 }
496 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
497
498 map = (struct sock_mapping *) sock->sk->sk_send_head;
499 if (!map) {
500 pvcalls_exit();
501 return -ENOTSOCK;
502 }
503
504 mutex_lock(&map->active.out_mutex);
505 if ((flags & MSG_DONTWAIT) && !pvcalls_front_write_todo(map)) {
506 mutex_unlock(&map->active.out_mutex);
507 pvcalls_exit();
508 return -EAGAIN;
509 }
510 if (len > INT_MAX)
511 len = INT_MAX;
512
513 again:
514 count++;
515 sent = __write_ring(map->active.ring,
516 &map->active.data, &msg->msg_iter,
517 len);
518 if (sent > 0) {
519 len -= sent;
520 tot_sent += sent;
521 notify_remote_via_irq(map->active.irq);
522 }
523 if (sent >= 0 && len > 0 && count < PVCALLS_FRONT_MAX_SPIN)
524 goto again;
525 if (sent < 0)
526 tot_sent = sent;
527
528 mutex_unlock(&map->active.out_mutex);
529 pvcalls_exit();
530 return tot_sent;
531 }
532
533 static int __read_ring(struct pvcalls_data_intf *intf,
534 struct pvcalls_data *data,
535 struct iov_iter *msg_iter,
536 size_t len, int flags)
537 {
538 RING_IDX cons, prod, size, masked_prod, masked_cons;
539 RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
540 int32_t error;
541
542 cons = intf->in_cons;
543 prod = intf->in_prod;
544 error = intf->in_error;
545 /* get pointers before reading from the ring */
546 virt_rmb();
547 if (error < 0)
548 return error;
549
550 size = pvcalls_queued(prod, cons, array_size);
551 masked_prod = pvcalls_mask(prod, array_size);
552 masked_cons = pvcalls_mask(cons, array_size);
553
554 if (size == 0)
555 return 0;
556
557 if (len > size)
558 len = size;
559
560 if (masked_prod > masked_cons) {
561 len = copy_to_iter(data->in + masked_cons, len, msg_iter);
562 } else {
563 if (len > (array_size - masked_cons)) {
564 int ret = copy_to_iter(data->in + masked_cons,
565 array_size - masked_cons, msg_iter);
566 if (ret != array_size - masked_cons) {
567 len = ret;
568 goto out;
569 }
570 len = ret + copy_to_iter(data->in, len - ret, msg_iter);
571 } else {
572 len = copy_to_iter(data->in + masked_cons, len, msg_iter);
573 }
574 }
575 out:
576 /* read data from the ring before increasing the index */
577 virt_mb();
578 if (!(flags & MSG_PEEK))
579 intf->in_cons += len;
580
581 return len;
582 }
583
584 int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
585 int flags)
586 {
587 struct pvcalls_bedata *bedata;
588 int ret;
589 struct sock_mapping *map;
590
591 if (flags & (MSG_CMSG_CLOEXEC|MSG_ERRQUEUE|MSG_OOB|MSG_TRUNC))
592 return -EOPNOTSUPP;
593
594 pvcalls_enter();
595 if (!pvcalls_front_dev) {
596 pvcalls_exit();
597 return -ENOTCONN;
598 }
599 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
600
601 map = (struct sock_mapping *) sock->sk->sk_send_head;
602 if (!map) {
603 pvcalls_exit();
604 return -ENOTSOCK;
605 }
606
607 mutex_lock(&map->active.in_mutex);
608 if (len > XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER))
609 len = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
610
611 while (!(flags & MSG_DONTWAIT) && !pvcalls_front_read_todo(map)) {
612 wait_event_interruptible(map->active.inflight_conn_req,
613 pvcalls_front_read_todo(map));
614 }
615 ret = __read_ring(map->active.ring, &map->active.data,
616 &msg->msg_iter, len, flags);
617
618 if (ret > 0)
619 notify_remote_via_irq(map->active.irq);
620 if (ret == 0)
621 ret = (flags & MSG_DONTWAIT) ? -EAGAIN : 0;
622 if (ret == -ENOTCONN)
623 ret = 0;
624
625 mutex_unlock(&map->active.in_mutex);
626 pvcalls_exit();
627 return ret;
628 }
629
630 int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
631 {
632 struct pvcalls_bedata *bedata;
633 struct sock_mapping *map = NULL;
634 struct xen_pvcalls_request *req;
635 int notify, req_id, ret;
636
637 if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
638 return -EOPNOTSUPP;
639
640 pvcalls_enter();
641 if (!pvcalls_front_dev) {
642 pvcalls_exit();
643 return -ENOTCONN;
644 }
645 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
646
647 map = (struct sock_mapping *) sock->sk->sk_send_head;
648 if (map == NULL) {
649 pvcalls_exit();
650 return -ENOTSOCK;
651 }
652
653 spin_lock(&bedata->socket_lock);
654 ret = get_request(bedata, &req_id);
655 if (ret < 0) {
656 spin_unlock(&bedata->socket_lock);
657 pvcalls_exit();
658 return ret;
659 }
660 req = RING_GET_REQUEST(&bedata->ring, req_id);
661 req->req_id = req_id;
662 map->sock = sock;
663 req->cmd = PVCALLS_BIND;
664 req->u.bind.id = (uintptr_t)map;
665 memcpy(req->u.bind.addr, addr, sizeof(*addr));
666 req->u.bind.len = addr_len;
667
668 init_waitqueue_head(&map->passive.inflight_accept_req);
669
670 map->active_socket = false;
671
672 bedata->ring.req_prod_pvt++;
673 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
674 spin_unlock(&bedata->socket_lock);
675 if (notify)
676 notify_remote_via_irq(bedata->irq);
677
678 wait_event(bedata->inflight_req,
679 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
680
681 /* read req_id, then the content */
682 smp_rmb();
683 ret = bedata->rsp[req_id].ret;
684 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
685
686 map->passive.status = PVCALLS_STATUS_BIND;
687 pvcalls_exit();
688 return 0;
689 }
690
691 int pvcalls_front_listen(struct socket *sock, int backlog)
692 {
693 struct pvcalls_bedata *bedata;
694 struct sock_mapping *map;
695 struct xen_pvcalls_request *req;
696 int notify, req_id, ret;
697
698 pvcalls_enter();
699 if (!pvcalls_front_dev) {
700 pvcalls_exit();
701 return -ENOTCONN;
702 }
703 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
704
705 map = (struct sock_mapping *) sock->sk->sk_send_head;
706 if (!map) {
707 pvcalls_exit();
708 return -ENOTSOCK;
709 }
710
711 if (map->passive.status != PVCALLS_STATUS_BIND) {
712 pvcalls_exit();
713 return -EOPNOTSUPP;
714 }
715
716 spin_lock(&bedata->socket_lock);
717 ret = get_request(bedata, &req_id);
718 if (ret < 0) {
719 spin_unlock(&bedata->socket_lock);
720 pvcalls_exit();
721 return ret;
722 }
723 req = RING_GET_REQUEST(&bedata->ring, req_id);
724 req->req_id = req_id;
725 req->cmd = PVCALLS_LISTEN;
726 req->u.listen.id = (uintptr_t) map;
727 req->u.listen.backlog = backlog;
728
729 bedata->ring.req_prod_pvt++;
730 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
731 spin_unlock(&bedata->socket_lock);
732 if (notify)
733 notify_remote_via_irq(bedata->irq);
734
735 wait_event(bedata->inflight_req,
736 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
737
738 /* read req_id, then the content */
739 smp_rmb();
740 ret = bedata->rsp[req_id].ret;
741 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
742
743 map->passive.status = PVCALLS_STATUS_LISTEN;
744 pvcalls_exit();
745 return ret;
746 }
747
748 int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
749 {
750 struct pvcalls_bedata *bedata;
751 struct sock_mapping *map;
752 struct sock_mapping *map2 = NULL;
753 struct xen_pvcalls_request *req;
754 int notify, req_id, ret, evtchn, nonblock;
755
756 pvcalls_enter();
757 if (!pvcalls_front_dev) {
758 pvcalls_exit();
759 return -ENOTCONN;
760 }
761 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
762
763 map = (struct sock_mapping *) sock->sk->sk_send_head;
764 if (!map) {
765 pvcalls_exit();
766 return -ENOTSOCK;
767 }
768
769 if (map->passive.status != PVCALLS_STATUS_LISTEN) {
770 pvcalls_exit();
771 return -EINVAL;
772 }
773
774 nonblock = flags & SOCK_NONBLOCK;
775 /*
776 * Backend only supports 1 inflight accept request, will return
777 * errors for the others
778 */
779 if (test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
780 (void *)&map->passive.flags)) {
781 req_id = READ_ONCE(map->passive.inflight_req_id);
782 if (req_id != PVCALLS_INVALID_ID &&
783 READ_ONCE(bedata->rsp[req_id].req_id) == req_id) {
784 map2 = map->passive.accept_map;
785 goto received;
786 }
787 if (nonblock) {
788 pvcalls_exit();
789 return -EAGAIN;
790 }
791 if (wait_event_interruptible(map->passive.inflight_accept_req,
792 !test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
793 (void *)&map->passive.flags))) {
794 pvcalls_exit();
795 return -EINTR;
796 }
797 }
798
799 spin_lock(&bedata->socket_lock);
800 ret = get_request(bedata, &req_id);
801 if (ret < 0) {
802 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
803 (void *)&map->passive.flags);
804 spin_unlock(&bedata->socket_lock);
805 pvcalls_exit();
806 return ret;
807 }
808 map2 = kzalloc(sizeof(*map2), GFP_ATOMIC);
809 if (map2 == NULL) {
810 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
811 (void *)&map->passive.flags);
812 spin_unlock(&bedata->socket_lock);
813 pvcalls_exit();
814 return -ENOMEM;
815 }
816 ret = create_active(map2, &evtchn);
817 if (ret < 0) {
818 kfree(map2);
819 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
820 (void *)&map->passive.flags);
821 spin_unlock(&bedata->socket_lock);
822 pvcalls_exit();
823 return ret;
824 }
825 list_add_tail(&map2->list, &bedata->socket_mappings);
826
827 req = RING_GET_REQUEST(&bedata->ring, req_id);
828 req->req_id = req_id;
829 req->cmd = PVCALLS_ACCEPT;
830 req->u.accept.id = (uintptr_t) map;
831 req->u.accept.ref = map2->active.ref;
832 req->u.accept.id_new = (uintptr_t) map2;
833 req->u.accept.evtchn = evtchn;
834 map->passive.accept_map = map2;
835
836 bedata->ring.req_prod_pvt++;
837 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
838 spin_unlock(&bedata->socket_lock);
839 if (notify)
840 notify_remote_via_irq(bedata->irq);
841 /* We could check if we have received a response before returning. */
842 if (nonblock) {
843 WRITE_ONCE(map->passive.inflight_req_id, req_id);
844 pvcalls_exit();
845 return -EAGAIN;
846 }
847
848 if (wait_event_interruptible(bedata->inflight_req,
849 READ_ONCE(bedata->rsp[req_id].req_id) == req_id)) {
850 pvcalls_exit();
851 return -EINTR;
852 }
853 /* read req_id, then the content */
854 smp_rmb();
855
856 received:
857 map2->sock = newsock;
858 newsock->sk = kzalloc(sizeof(*newsock->sk), GFP_KERNEL);
859 if (!newsock->sk) {
860 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
861 map->passive.inflight_req_id = PVCALLS_INVALID_ID;
862 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
863 (void *)&map->passive.flags);
864 pvcalls_front_free_map(bedata, map2);
865 pvcalls_exit();
866 return -ENOMEM;
867 }
868 newsock->sk->sk_send_head = (void *)map2;
869
870 ret = bedata->rsp[req_id].ret;
871 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
872 map->passive.inflight_req_id = PVCALLS_INVALID_ID;
873
874 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags);
875 wake_up(&map->passive.inflight_accept_req);
876
877 pvcalls_exit();
878 return ret;
879 }
880
881 static unsigned int pvcalls_front_poll_passive(struct file *file,
882 struct pvcalls_bedata *bedata,
883 struct sock_mapping *map,
884 poll_table *wait)
885 {
886 int notify, req_id, ret;
887 struct xen_pvcalls_request *req;
888
889 if (test_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
890 (void *)&map->passive.flags)) {
891 uint32_t req_id = READ_ONCE(map->passive.inflight_req_id);
892
893 if (req_id != PVCALLS_INVALID_ID &&
894 READ_ONCE(bedata->rsp[req_id].req_id) == req_id)
895 return POLLIN | POLLRDNORM;
896
897 poll_wait(file, &map->passive.inflight_accept_req, wait);
898 return 0;
899 }
900
901 if (test_and_clear_bit(PVCALLS_FLAG_POLL_RET,
902 (void *)&map->passive.flags))
903 return POLLIN | POLLRDNORM;
904
905 /*
906 * First check RET, then INFLIGHT. No barriers necessary to
907 * ensure execution ordering because of the conditional
908 * instructions creating control dependencies.
909 */
910
911 if (test_and_set_bit(PVCALLS_FLAG_POLL_INFLIGHT,
912 (void *)&map->passive.flags)) {
913 poll_wait(file, &bedata->inflight_req, wait);
914 return 0;
915 }
916
917 spin_lock(&bedata->socket_lock);
918 ret = get_request(bedata, &req_id);
919 if (ret < 0) {
920 spin_unlock(&bedata->socket_lock);
921 return ret;
922 }
923 req = RING_GET_REQUEST(&bedata->ring, req_id);
924 req->req_id = req_id;
925 req->cmd = PVCALLS_POLL;
926 req->u.poll.id = (uintptr_t) map;
927
928 bedata->ring.req_prod_pvt++;
929 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
930 spin_unlock(&bedata->socket_lock);
931 if (notify)
932 notify_remote_via_irq(bedata->irq);
933
934 poll_wait(file, &bedata->inflight_req, wait);
935 return 0;
936 }
937
938 static unsigned int pvcalls_front_poll_active(struct file *file,
939 struct pvcalls_bedata *bedata,
940 struct sock_mapping *map,
941 poll_table *wait)
942 {
943 unsigned int mask = 0;
944 int32_t in_error, out_error;
945 struct pvcalls_data_intf *intf = map->active.ring;
946
947 out_error = intf->out_error;
948 in_error = intf->in_error;
949
950 poll_wait(file, &map->active.inflight_conn_req, wait);
951 if (pvcalls_front_write_todo(map))
952 mask |= POLLOUT | POLLWRNORM;
953 if (pvcalls_front_read_todo(map))
954 mask |= POLLIN | POLLRDNORM;
955 if (in_error != 0 || out_error != 0)
956 mask |= POLLERR;
957
958 return mask;
959 }
960
961 unsigned int pvcalls_front_poll(struct file *file, struct socket *sock,
962 poll_table *wait)
963 {
964 struct pvcalls_bedata *bedata;
965 struct sock_mapping *map;
966 int ret;
967
968 pvcalls_enter();
969 if (!pvcalls_front_dev) {
970 pvcalls_exit();
971 return POLLNVAL;
972 }
973 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
974
975 map = (struct sock_mapping *) sock->sk->sk_send_head;
976 if (!map) {
977 pvcalls_exit();
978 return POLLNVAL;
979 }
980 if (map->active_socket)
981 ret = pvcalls_front_poll_active(file, bedata, map, wait);
982 else
983 ret = pvcalls_front_poll_passive(file, bedata, map, wait);
984 pvcalls_exit();
985 return ret;
986 }
987
988 int pvcalls_front_release(struct socket *sock)
989 {
990 struct pvcalls_bedata *bedata;
991 struct sock_mapping *map;
992 int req_id, notify, ret;
993 struct xen_pvcalls_request *req;
994
995 if (sock->sk == NULL)
996 return 0;
997
998 pvcalls_enter();
999 if (!pvcalls_front_dev) {
1000 pvcalls_exit();
1001 return -EIO;
1002 }
1003
1004 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
1005
1006 map = (struct sock_mapping *) sock->sk->sk_send_head;
1007 if (map == NULL) {
1008 pvcalls_exit();
1009 return 0;
1010 }
1011
1012 spin_lock(&bedata->socket_lock);
1013 ret = get_request(bedata, &req_id);
1014 if (ret < 0) {
1015 spin_unlock(&bedata->socket_lock);
1016 pvcalls_exit();
1017 return ret;
1018 }
1019 sock->sk->sk_send_head = NULL;
1020
1021 req = RING_GET_REQUEST(&bedata->ring, req_id);
1022 req->req_id = req_id;
1023 req->cmd = PVCALLS_RELEASE;
1024 req->u.release.id = (uintptr_t)map;
1025
1026 bedata->ring.req_prod_pvt++;
1027 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
1028 spin_unlock(&bedata->socket_lock);
1029 if (notify)
1030 notify_remote_via_irq(bedata->irq);
1031
1032 wait_event(bedata->inflight_req,
1033 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
1034
1035 if (map->active_socket) {
1036 /*
1037 * Set in_error and wake up inflight_conn_req to force
1038 * recvmsg waiters to exit.
1039 */
1040 map->active.ring->in_error = -EBADF;
1041 wake_up_interruptible(&map->active.inflight_conn_req);
1042
1043 /*
1044 * We need to make sure that sendmsg/recvmsg on this socket have
1045 * not started before we've cleared sk_send_head here. The
1046 * easiest (though not optimal) way to guarantee this is to see
1047 * that no pvcall (other than us) is in progress.
1048 */
1049 while (atomic_read(&pvcalls_refcount) > 1)
1050 cpu_relax();
1051
1052 pvcalls_front_free_map(bedata, map);
1053 } else {
1054 spin_lock(&bedata->socket_lock);
1055 list_del(&map->list);
1056 spin_unlock(&bedata->socket_lock);
1057 if (READ_ONCE(map->passive.inflight_req_id) !=
1058 PVCALLS_INVALID_ID) {
1059 pvcalls_front_free_map(bedata,
1060 map->passive.accept_map);
1061 }
1062 kfree(map);
1063 }
1064 WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID);
1065
1066 pvcalls_exit();
1067 return 0;
1068 }
1069
1070 static const struct xenbus_device_id pvcalls_front_ids[] = {
1071 { "pvcalls" },
1072 { "" }
1073 };
1074
1075 static int pvcalls_front_remove(struct xenbus_device *dev)
1076 {
1077 struct pvcalls_bedata *bedata;
1078 struct sock_mapping *map = NULL, *n;
1079
1080 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
1081 dev_set_drvdata(&dev->dev, NULL);
1082 pvcalls_front_dev = NULL;
1083 if (bedata->irq >= 0)
1084 unbind_from_irqhandler(bedata->irq, dev);
1085
1086 list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
1087 map->sock->sk->sk_send_head = NULL;
1088 if (map->active_socket) {
1089 map->active.ring->in_error = -EBADF;
1090 wake_up_interruptible(&map->active.inflight_conn_req);
1091 }
1092 }
1093
1094 smp_mb();
1095 while (atomic_read(&pvcalls_refcount) > 0)
1096 cpu_relax();
1097 list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
1098 if (map->active_socket) {
1099 /* No need to lock, refcount is 0 */
1100 pvcalls_front_free_map(bedata, map);
1101 } else {
1102 list_del(&map->list);
1103 kfree(map);
1104 }
1105 }
1106 if (bedata->ref != -1)
1107 gnttab_end_foreign_access(bedata->ref, 0, 0);
1108 kfree(bedata->ring.sring);
1109 kfree(bedata);
1110 xenbus_switch_state(dev, XenbusStateClosed);
1111 return 0;
1112 }
1113
1114 static int pvcalls_front_probe(struct xenbus_device *dev,
1115 const struct xenbus_device_id *id)
1116 {
1117 int ret = -ENOMEM, evtchn, i;
1118 unsigned int max_page_order, function_calls, len;
1119 char *versions;
1120 grant_ref_t gref_head = 0;
1121 struct xenbus_transaction xbt;
1122 struct pvcalls_bedata *bedata = NULL;
1123 struct xen_pvcalls_sring *sring;
1124
1125 if (pvcalls_front_dev != NULL) {
1126 dev_err(&dev->dev, "only one PV Calls connection supported\n");
1127 return -EINVAL;
1128 }
1129
1130 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
1131 if (IS_ERR(versions))
1132 return PTR_ERR(versions);
1133 if (!len)
1134 return -EINVAL;
1135 if (strcmp(versions, "1")) {
1136 kfree(versions);
1137 return -EINVAL;
1138 }
1139 kfree(versions);
1140 max_page_order = xenbus_read_unsigned(dev->otherend,
1141 "max-page-order", 0);
1142 if (max_page_order < PVCALLS_RING_ORDER)
1143 return -ENODEV;
1144 function_calls = xenbus_read_unsigned(dev->otherend,
1145 "function-calls", 0);
1146 /* See XENBUS_FUNCTIONS_CALLS in pvcalls.h */
1147 if (function_calls != 1)
1148 return -ENODEV;
1149 pr_info("%s max-page-order is %u\n", __func__, max_page_order);
1150
1151 bedata = kzalloc(sizeof(struct pvcalls_bedata), GFP_KERNEL);
1152 if (!bedata)
1153 return -ENOMEM;
1154
1155 dev_set_drvdata(&dev->dev, bedata);
1156 pvcalls_front_dev = dev;
1157 init_waitqueue_head(&bedata->inflight_req);
1158 INIT_LIST_HEAD(&bedata->socket_mappings);
1159 spin_lock_init(&bedata->socket_lock);
1160 bedata->irq = -1;
1161 bedata->ref = -1;
1162
1163 for (i = 0; i < PVCALLS_NR_RSP_PER_RING; i++)
1164 bedata->rsp[i].req_id = PVCALLS_INVALID_ID;
1165
1166 sring = (struct xen_pvcalls_sring *) __get_free_page(GFP_KERNEL |
1167 __GFP_ZERO);
1168 if (!sring)
1169 goto error;
1170 SHARED_RING_INIT(sring);
1171 FRONT_RING_INIT(&bedata->ring, sring, XEN_PAGE_SIZE);
1172
1173 ret = xenbus_alloc_evtchn(dev, &evtchn);
1174 if (ret)
1175 goto error;
1176
1177 bedata->irq = bind_evtchn_to_irqhandler(evtchn,
1178 pvcalls_front_event_handler,
1179 0, "pvcalls-frontend", dev);
1180 if (bedata->irq < 0) {
1181 ret = bedata->irq;
1182 goto error;
1183 }
1184
1185 ret = gnttab_alloc_grant_references(1, &gref_head);
1186 if (ret < 0)
1187 goto error;
1188 ret = gnttab_claim_grant_reference(&gref_head);
1189 if (ret < 0)
1190 goto error;
1191 bedata->ref = ret;
1192 gnttab_grant_foreign_access_ref(bedata->ref, dev->otherend_id,
1193 virt_to_gfn((void *)sring), 0);
1194
1195 again:
1196 ret = xenbus_transaction_start(&xbt);
1197 if (ret) {
1198 xenbus_dev_fatal(dev, ret, "starting transaction");
1199 goto error;
1200 }
1201 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
1202 if (ret)
1203 goto error_xenbus;
1204 ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", bedata->ref);
1205 if (ret)
1206 goto error_xenbus;
1207 ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
1208 evtchn);
1209 if (ret)
1210 goto error_xenbus;
1211 ret = xenbus_transaction_end(xbt, 0);
1212 if (ret) {
1213 if (ret == -EAGAIN)
1214 goto again;
1215 xenbus_dev_fatal(dev, ret, "completing transaction");
1216 goto error;
1217 }
1218 xenbus_switch_state(dev, XenbusStateInitialised);
1219
1220 return 0;
1221
1222 error_xenbus:
1223 xenbus_transaction_end(xbt, 1);
1224 xenbus_dev_fatal(dev, ret, "writing xenstore");
1225 error:
1226 pvcalls_front_remove(dev);
1227 return ret;
1228 }
1229
1230 static void pvcalls_front_changed(struct xenbus_device *dev,
1231 enum xenbus_state backend_state)
1232 {
1233 switch (backend_state) {
1234 case XenbusStateReconfiguring:
1235 case XenbusStateReconfigured:
1236 case XenbusStateInitialising:
1237 case XenbusStateInitialised:
1238 case XenbusStateUnknown:
1239 break;
1240
1241 case XenbusStateInitWait:
1242 break;
1243
1244 case XenbusStateConnected:
1245 xenbus_switch_state(dev, XenbusStateConnected);
1246 break;
1247
1248 case XenbusStateClosed:
1249 if (dev->state == XenbusStateClosed)
1250 break;
1251 /* Missed the backend's CLOSING state */
1252 /* fall through */
1253 case XenbusStateClosing:
1254 xenbus_frontend_closed(dev);
1255 break;
1256 }
1257 }
1258
1259 static struct xenbus_driver pvcalls_front_driver = {
1260 .ids = pvcalls_front_ids,
1261 .probe = pvcalls_front_probe,
1262 .remove = pvcalls_front_remove,
1263 .otherend_changed = pvcalls_front_changed,
1264 };
1265
1266 static int __init pvcalls_frontend_init(void)
1267 {
1268 if (!xen_domain())
1269 return -ENODEV;
1270
1271 pr_info("Initialising Xen pvcalls frontend driver\n");
1272
1273 return xenbus_register_frontend(&pvcalls_front_driver);
1274 }
1275
1276 module_init(pvcalls_frontend_init);
1277
1278 MODULE_DESCRIPTION("Xen PV Calls frontend driver");
1279 MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>");
1280 MODULE_LICENSE("GPL");
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