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treewide: remove redundant IS_ERR() before error code check
[linux/fpc-iii.git] / drivers / xen / pvcalls-front.c
blob57592a6b5c9e3bbc699996ac5e2ab70aab591d16
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * (c) 2017 Stefano Stabellini <stefano@aporeto.com>
4 */
5
6 #include <linux/module.h>
7 #include <linux/net.h>
8 #include <linux/socket.h>
9
10 #include <net/sock.h>
11
12 #include <xen/events.h>
13 #include <xen/grant_table.h>
14 #include <xen/xen.h>
15 #include <xen/xenbus.h>
16 #include <xen/interface/io/pvcalls.h>
17
18 #include "pvcalls-front.h"
19
20 #define PVCALLS_INVALID_ID UINT_MAX
21 #define PVCALLS_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
22 #define PVCALLS_NR_RSP_PER_RING __CONST_RING_SIZE(xen_pvcalls, XEN_PAGE_SIZE)
23 #define PVCALLS_FRONT_MAX_SPIN 5000
24
25 static struct proto pvcalls_proto = {
26 .name = "PVCalls",
27 .owner = THIS_MODULE,
28 .obj_size = sizeof(struct sock),
29 };
30
31 struct pvcalls_bedata {
32 struct xen_pvcalls_front_ring ring;
33 grant_ref_t ref;
34 int irq;
35
36 struct list_head socket_mappings;
37 spinlock_t socket_lock;
38
39 wait_queue_head_t inflight_req;
40 struct xen_pvcalls_response rsp[PVCALLS_NR_RSP_PER_RING];
41 };
42 /* Only one front/back connection supported. */
43 static struct xenbus_device *pvcalls_front_dev;
44 static atomic_t pvcalls_refcount;
45
46 /* first increment refcount, then proceed */
47 #define pvcalls_enter() { \
48 atomic_inc(&pvcalls_refcount); \
49 }
50
51 /* first complete other operations, then decrement refcount */
52 #define pvcalls_exit() { \
53 atomic_dec(&pvcalls_refcount); \
54 }
55
56 struct sock_mapping {
57 bool active_socket;
58 struct list_head list;
59 struct socket *sock;
60 atomic_t refcount;
61 union {
62 struct {
63 int irq;
64 grant_ref_t ref;
65 struct pvcalls_data_intf *ring;
66 struct pvcalls_data data;
67 struct mutex in_mutex;
68 struct mutex out_mutex;
69
70 wait_queue_head_t inflight_conn_req;
71 } active;
72 struct {
73 /*
74 * Socket status, needs to be 64-bit aligned due to the
75 * test_and_* functions which have this requirement on arm64.
76 */
77 #define PVCALLS_STATUS_UNINITALIZED 0
78 #define PVCALLS_STATUS_BIND 1
79 #define PVCALLS_STATUS_LISTEN 2
80 uint8_t status __attribute__((aligned(8)));
81 /*
82 * Internal state-machine flags.
83 * Only one accept operation can be inflight for a socket.
84 * Only one poll operation can be inflight for a given socket.
85 * flags needs to be 64-bit aligned due to the test_and_*
86 * functions which have this requirement on arm64.
87 */
88 #define PVCALLS_FLAG_ACCEPT_INFLIGHT 0
89 #define PVCALLS_FLAG_POLL_INFLIGHT 1
90 #define PVCALLS_FLAG_POLL_RET 2
91 uint8_t flags __attribute__((aligned(8)));
92 uint32_t inflight_req_id;
93 struct sock_mapping *accept_map;
94 wait_queue_head_t inflight_accept_req;
95 } passive;
96 };
97 };
98
99 static inline struct sock_mapping *pvcalls_enter_sock(struct socket *sock)
100 {
101 struct sock_mapping *map;
102
103 if (!pvcalls_front_dev ||
104 dev_get_drvdata(&pvcalls_front_dev->dev) == NULL)
105 return ERR_PTR(-ENOTCONN);
106
107 map = (struct sock_mapping *)sock->sk->sk_send_head;
108 if (map == NULL)
109 return ERR_PTR(-ENOTSOCK);
110
111 pvcalls_enter();
112 atomic_inc(&map->refcount);
113 return map;
114 }
115
116 static inline void pvcalls_exit_sock(struct socket *sock)
117 {
118 struct sock_mapping *map;
119
120 map = (struct sock_mapping *)sock->sk->sk_send_head;
121 atomic_dec(&map->refcount);
122 pvcalls_exit();
123 }
124
125 static inline int get_request(struct pvcalls_bedata *bedata, int *req_id)
126 {
127 *req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1);
128 if (RING_FULL(&bedata->ring) ||
129 bedata->rsp[*req_id].req_id != PVCALLS_INVALID_ID)
130 return -EAGAIN;
131 return 0;
132 }
133
134 static bool pvcalls_front_write_todo(struct sock_mapping *map)
135 {
136 struct pvcalls_data_intf *intf = map->active.ring;
137 RING_IDX cons, prod, size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
138 int32_t error;
139
140 error = intf->out_error;
141 if (error == -ENOTCONN)
142 return false;
143 if (error != 0)
144 return true;
145
146 cons = intf->out_cons;
147 prod = intf->out_prod;
148 return !!(size - pvcalls_queued(prod, cons, size));
149 }
150
151 static bool pvcalls_front_read_todo(struct sock_mapping *map)
152 {
153 struct pvcalls_data_intf *intf = map->active.ring;
154 RING_IDX cons, prod;
155 int32_t error;
156
157 cons = intf->in_cons;
158 prod = intf->in_prod;
159 error = intf->in_error;
160 return (error != 0 ||
161 pvcalls_queued(prod, cons,
162 XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER)) != 0);
163 }
164
165 static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
166 {
167 struct xenbus_device *dev = dev_id;
168 struct pvcalls_bedata *bedata;
169 struct xen_pvcalls_response *rsp;
170 uint8_t *src, *dst;
171 int req_id = 0, more = 0, done = 0;
172
173 if (dev == NULL)
174 return IRQ_HANDLED;
175
176 pvcalls_enter();
177 bedata = dev_get_drvdata(&dev->dev);
178 if (bedata == NULL) {
179 pvcalls_exit();
180 return IRQ_HANDLED;
181 }
182
183 again:
184 while (RING_HAS_UNCONSUMED_RESPONSES(&bedata->ring)) {
185 rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons);
186
187 req_id = rsp->req_id;
188 if (rsp->cmd == PVCALLS_POLL) {
189 struct sock_mapping *map = (struct sock_mapping *)(uintptr_t)
190 rsp->u.poll.id;
191
192 clear_bit(PVCALLS_FLAG_POLL_INFLIGHT,
193 (void *)&map->passive.flags);
194 /*
195 * clear INFLIGHT, then set RET. It pairs with
196 * the checks at the beginning of
197 * pvcalls_front_poll_passive.
198 */
199 smp_wmb();
200 set_bit(PVCALLS_FLAG_POLL_RET,
201 (void *)&map->passive.flags);
202 } else {
203 dst = (uint8_t *)&bedata->rsp[req_id] +
204 sizeof(rsp->req_id);
205 src = (uint8_t *)rsp + sizeof(rsp->req_id);
206 memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id));
207 /*
208 * First copy the rest of the data, then req_id. It is
209 * paired with the barrier when accessing bedata->rsp.
210 */
211 smp_wmb();
212 bedata->rsp[req_id].req_id = req_id;
213 }
214
215 done = 1;
216 bedata->ring.rsp_cons++;
217 }
218
219 RING_FINAL_CHECK_FOR_RESPONSES(&bedata->ring, more);
220 if (more)
221 goto again;
222 if (done)
223 wake_up(&bedata->inflight_req);
224 pvcalls_exit();
225 return IRQ_HANDLED;
226 }
227
228 static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
229 struct sock_mapping *map)
230 {
231 int i;
232
233 unbind_from_irqhandler(map->active.irq, map);
234
235 spin_lock(&bedata->socket_lock);
236 if (!list_empty(&map->list))
237 list_del_init(&map->list);
238 spin_unlock(&bedata->socket_lock);
239
240 for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
241 gnttab_end_foreign_access(map->active.ring->ref[i], 0, 0);
242 gnttab_end_foreign_access(map->active.ref, 0, 0);
243 free_page((unsigned long)map->active.ring);
244
245 kfree(map);
246 }
247
248 static irqreturn_t pvcalls_front_conn_handler(int irq, void *sock_map)
249 {
250 struct sock_mapping *map = sock_map;
251
252 if (map == NULL)
253 return IRQ_HANDLED;
254
255 wake_up_interruptible(&map->active.inflight_conn_req);
256
257 return IRQ_HANDLED;
258 }
259
260 int pvcalls_front_socket(struct socket *sock)
261 {
262 struct pvcalls_bedata *bedata;
263 struct sock_mapping *map = NULL;
264 struct xen_pvcalls_request *req;
265 int notify, req_id, ret;
266
267 /*
268 * PVCalls only supports domain AF_INET,
269 * type SOCK_STREAM and protocol 0 sockets for now.
270 *
271 * Check socket type here, AF_INET and protocol checks are done
272 * by the caller.
273 */
274 if (sock->type != SOCK_STREAM)
275 return -EOPNOTSUPP;
276
277 pvcalls_enter();
278 if (!pvcalls_front_dev) {
279 pvcalls_exit();
280 return -EACCES;
281 }
282 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
283
284 map = kzalloc(sizeof(*map), GFP_KERNEL);
285 if (map == NULL) {
286 pvcalls_exit();
287 return -ENOMEM;
288 }
289
290 spin_lock(&bedata->socket_lock);
291
292 ret = get_request(bedata, &req_id);
293 if (ret < 0) {
294 kfree(map);
295 spin_unlock(&bedata->socket_lock);
296 pvcalls_exit();
297 return ret;
298 }
299
300 /*
301 * sock->sk->sk_send_head is not used for ip sockets: reuse the
302 * field to store a pointer to the struct sock_mapping
303 * corresponding to the socket. This way, we can easily get the
304 * struct sock_mapping from the struct socket.
305 */
306 sock->sk->sk_send_head = (void *)map;
307 list_add_tail(&map->list, &bedata->socket_mappings);
308
309 req = RING_GET_REQUEST(&bedata->ring, req_id);
310 req->req_id = req_id;
311 req->cmd = PVCALLS_SOCKET;
312 req->u.socket.id = (uintptr_t) map;
313 req->u.socket.domain = AF_INET;
314 req->u.socket.type = SOCK_STREAM;
315 req->u.socket.protocol = IPPROTO_IP;
316
317 bedata->ring.req_prod_pvt++;
318 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
319 spin_unlock(&bedata->socket_lock);
320 if (notify)
321 notify_remote_via_irq(bedata->irq);
322
323 wait_event(bedata->inflight_req,
324 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
325
326 /* read req_id, then the content */
327 smp_rmb();
328 ret = bedata->rsp[req_id].ret;
329 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
330
331 pvcalls_exit();
332 return ret;
333 }
334
335 static void free_active_ring(struct sock_mapping *map)
336 {
337 if (!map->active.ring)
338 return;
339
340 free_pages((unsigned long)map->active.data.in,
341 map->active.ring->ring_order);
342 free_page((unsigned long)map->active.ring);
343 }
344
345 static int alloc_active_ring(struct sock_mapping *map)
346 {
347 void *bytes;
348
349 map->active.ring = (struct pvcalls_data_intf *)
350 get_zeroed_page(GFP_KERNEL);
351 if (!map->active.ring)
352 goto out;
353
354 map->active.ring->ring_order = PVCALLS_RING_ORDER;
355 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
356 PVCALLS_RING_ORDER);
357 if (!bytes)
358 goto out;
359
360 map->active.data.in = bytes;
361 map->active.data.out = bytes +
362 XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
363
364 return 0;
365
366 out:
367 free_active_ring(map);
368 return -ENOMEM;
369 }
370
371 static int create_active(struct sock_mapping *map, int *evtchn)
372 {
373 void *bytes;
374 int ret = -ENOMEM, irq = -1, i;
375
376 *evtchn = -1;
377 init_waitqueue_head(&map->active.inflight_conn_req);
378
379 bytes = map->active.data.in;
380 for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
381 map->active.ring->ref[i] = gnttab_grant_foreign_access(
382 pvcalls_front_dev->otherend_id,
383 pfn_to_gfn(virt_to_pfn(bytes) + i), 0);
384
385 map->active.ref = gnttab_grant_foreign_access(
386 pvcalls_front_dev->otherend_id,
387 pfn_to_gfn(virt_to_pfn((void *)map->active.ring)), 0);
388
389 ret = xenbus_alloc_evtchn(pvcalls_front_dev, evtchn);
390 if (ret)
391 goto out_error;
392 irq = bind_evtchn_to_irqhandler(*evtchn, pvcalls_front_conn_handler,
393 0, "pvcalls-frontend", map);
394 if (irq < 0) {
395 ret = irq;
396 goto out_error;
397 }
398
399 map->active.irq = irq;
400 map->active_socket = true;
401 mutex_init(&map->active.in_mutex);
402 mutex_init(&map->active.out_mutex);
403
404 return 0;
405
406 out_error:
407 if (*evtchn >= 0)
408 xenbus_free_evtchn(pvcalls_front_dev, *evtchn);
409 return ret;
410 }
411
412 int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
413 int addr_len, int flags)
414 {
415 struct pvcalls_bedata *bedata;
416 struct sock_mapping *map = NULL;
417 struct xen_pvcalls_request *req;
418 int notify, req_id, ret, evtchn;
419
420 if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
421 return -EOPNOTSUPP;
422
423 map = pvcalls_enter_sock(sock);
424 if (IS_ERR(map))
425 return PTR_ERR(map);
426
427 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
428 ret = alloc_active_ring(map);
429 if (ret < 0) {
430 pvcalls_exit_sock(sock);
431 return ret;
432 }
433
434 spin_lock(&bedata->socket_lock);
435 ret = get_request(bedata, &req_id);
436 if (ret < 0) {
437 spin_unlock(&bedata->socket_lock);
438 free_active_ring(map);
439 pvcalls_exit_sock(sock);
440 return ret;
441 }
442 ret = create_active(map, &evtchn);
443 if (ret < 0) {
444 spin_unlock(&bedata->socket_lock);
445 free_active_ring(map);
446 pvcalls_exit_sock(sock);
447 return ret;
448 }
449
450 req = RING_GET_REQUEST(&bedata->ring, req_id);
451 req->req_id = req_id;
452 req->cmd = PVCALLS_CONNECT;
453 req->u.connect.id = (uintptr_t)map;
454 req->u.connect.len = addr_len;
455 req->u.connect.flags = flags;
456 req->u.connect.ref = map->active.ref;
457 req->u.connect.evtchn = evtchn;
458 memcpy(req->u.connect.addr, addr, sizeof(*addr));
459
460 map->sock = sock;
461
462 bedata->ring.req_prod_pvt++;
463 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
464 spin_unlock(&bedata->socket_lock);
465
466 if (notify)
467 notify_remote_via_irq(bedata->irq);
468
469 wait_event(bedata->inflight_req,
470 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
471
472 /* read req_id, then the content */
473 smp_rmb();
474 ret = bedata->rsp[req_id].ret;
475 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
476 pvcalls_exit_sock(sock);
477 return ret;
478 }
479
480 static int __write_ring(struct pvcalls_data_intf *intf,
481 struct pvcalls_data *data,
482 struct iov_iter *msg_iter,
483 int len)
484 {
485 RING_IDX cons, prod, size, masked_prod, masked_cons;
486 RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
487 int32_t error;
488
489 error = intf->out_error;
490 if (error < 0)
491 return error;
492 cons = intf->out_cons;
493 prod = intf->out_prod;
494 /* read indexes before continuing */
495 virt_mb();
496
497 size = pvcalls_queued(prod, cons, array_size);
498 if (size > array_size)
499 return -EINVAL;
500 if (size == array_size)
501 return 0;
502 if (len > array_size - size)
503 len = array_size - size;
504
505 masked_prod = pvcalls_mask(prod, array_size);
506 masked_cons = pvcalls_mask(cons, array_size);
507
508 if (masked_prod < masked_cons) {
509 len = copy_from_iter(data->out + masked_prod, len, msg_iter);
510 } else {
511 if (len > array_size - masked_prod) {
512 int ret = copy_from_iter(data->out + masked_prod,
513 array_size - masked_prod, msg_iter);
514 if (ret != array_size - masked_prod) {
515 len = ret;
516 goto out;
517 }
518 len = ret + copy_from_iter(data->out, len - ret, msg_iter);
519 } else {
520 len = copy_from_iter(data->out + masked_prod, len, msg_iter);
521 }
522 }
523 out:
524 /* write to ring before updating pointer */
525 virt_wmb();
526 intf->out_prod += len;
527
528 return len;
529 }
530
531 int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg,
532 size_t len)
533 {
534 struct sock_mapping *map;
535 int sent, tot_sent = 0;
536 int count = 0, flags;
537
538 flags = msg->msg_flags;
539 if (flags & (MSG_CONFIRM|MSG_DONTROUTE|MSG_EOR|MSG_OOB))
540 return -EOPNOTSUPP;
541
542 map = pvcalls_enter_sock(sock);
543 if (IS_ERR(map))
544 return PTR_ERR(map);
545
546 mutex_lock(&map->active.out_mutex);
547 if ((flags & MSG_DONTWAIT) && !pvcalls_front_write_todo(map)) {
548 mutex_unlock(&map->active.out_mutex);
549 pvcalls_exit_sock(sock);
550 return -EAGAIN;
551 }
552 if (len > INT_MAX)
553 len = INT_MAX;
554
555 again:
556 count++;
557 sent = __write_ring(map->active.ring,
558 &map->active.data, &msg->msg_iter,
559 len);
560 if (sent > 0) {
561 len -= sent;
562 tot_sent += sent;
563 notify_remote_via_irq(map->active.irq);
564 }
565 if (sent >= 0 && len > 0 && count < PVCALLS_FRONT_MAX_SPIN)
566 goto again;
567 if (sent < 0)
568 tot_sent = sent;
569
570 mutex_unlock(&map->active.out_mutex);
571 pvcalls_exit_sock(sock);
572 return tot_sent;
573 }
574
575 static int __read_ring(struct pvcalls_data_intf *intf,
576 struct pvcalls_data *data,
577 struct iov_iter *msg_iter,
578 size_t len, int flags)
579 {
580 RING_IDX cons, prod, size, masked_prod, masked_cons;
581 RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
582 int32_t error;
583
584 cons = intf->in_cons;
585 prod = intf->in_prod;
586 error = intf->in_error;
587 /* get pointers before reading from the ring */
588 virt_rmb();
589
590 size = pvcalls_queued(prod, cons, array_size);
591 masked_prod = pvcalls_mask(prod, array_size);
592 masked_cons = pvcalls_mask(cons, array_size);
593
594 if (size == 0)
595 return error ?: size;
596
597 if (len > size)
598 len = size;
599
600 if (masked_prod > masked_cons) {
601 len = copy_to_iter(data->in + masked_cons, len, msg_iter);
602 } else {
603 if (len > (array_size - masked_cons)) {
604 int ret = copy_to_iter(data->in + masked_cons,
605 array_size - masked_cons, msg_iter);
606 if (ret != array_size - masked_cons) {
607 len = ret;
608 goto out;
609 }
610 len = ret + copy_to_iter(data->in, len - ret, msg_iter);
611 } else {
612 len = copy_to_iter(data->in + masked_cons, len, msg_iter);
613 }
614 }
615 out:
616 /* read data from the ring before increasing the index */
617 virt_mb();
618 if (!(flags & MSG_PEEK))
619 intf->in_cons += len;
620
621 return len;
622 }
623
624 int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
625 int flags)
626 {
627 int ret;
628 struct sock_mapping *map;
629
630 if (flags & (MSG_CMSG_CLOEXEC|MSG_ERRQUEUE|MSG_OOB|MSG_TRUNC))
631 return -EOPNOTSUPP;
632
633 map = pvcalls_enter_sock(sock);
634 if (IS_ERR(map))
635 return PTR_ERR(map);
636
637 mutex_lock(&map->active.in_mutex);
638 if (len > XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER))
639 len = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
640
641 while (!(flags & MSG_DONTWAIT) && !pvcalls_front_read_todo(map)) {
642 wait_event_interruptible(map->active.inflight_conn_req,
643 pvcalls_front_read_todo(map));
644 }
645 ret = __read_ring(map->active.ring, &map->active.data,
646 &msg->msg_iter, len, flags);
647
648 if (ret > 0)
649 notify_remote_via_irq(map->active.irq);
650 if (ret == 0)
651 ret = (flags & MSG_DONTWAIT) ? -EAGAIN : 0;
652 if (ret == -ENOTCONN)
653 ret = 0;
654
655 mutex_unlock(&map->active.in_mutex);
656 pvcalls_exit_sock(sock);
657 return ret;
658 }
659
660 int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
661 {
662 struct pvcalls_bedata *bedata;
663 struct sock_mapping *map = NULL;
664 struct xen_pvcalls_request *req;
665 int notify, req_id, ret;
666
667 if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
668 return -EOPNOTSUPP;
669
670 map = pvcalls_enter_sock(sock);
671 if (IS_ERR(map))
672 return PTR_ERR(map);
673 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
674
675 spin_lock(&bedata->socket_lock);
676 ret = get_request(bedata, &req_id);
677 if (ret < 0) {
678 spin_unlock(&bedata->socket_lock);
679 pvcalls_exit_sock(sock);
680 return ret;
681 }
682 req = RING_GET_REQUEST(&bedata->ring, req_id);
683 req->req_id = req_id;
684 map->sock = sock;
685 req->cmd = PVCALLS_BIND;
686 req->u.bind.id = (uintptr_t)map;
687 memcpy(req->u.bind.addr, addr, sizeof(*addr));
688 req->u.bind.len = addr_len;
689
690 init_waitqueue_head(&map->passive.inflight_accept_req);
691
692 map->active_socket = false;
693
694 bedata->ring.req_prod_pvt++;
695 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
696 spin_unlock(&bedata->socket_lock);
697 if (notify)
698 notify_remote_via_irq(bedata->irq);
699
700 wait_event(bedata->inflight_req,
701 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
702
703 /* read req_id, then the content */
704 smp_rmb();
705 ret = bedata->rsp[req_id].ret;
706 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
707
708 map->passive.status = PVCALLS_STATUS_BIND;
709 pvcalls_exit_sock(sock);
710 return 0;
711 }
712
713 int pvcalls_front_listen(struct socket *sock, int backlog)
714 {
715 struct pvcalls_bedata *bedata;
716 struct sock_mapping *map;
717 struct xen_pvcalls_request *req;
718 int notify, req_id, ret;
719
720 map = pvcalls_enter_sock(sock);
721 if (IS_ERR(map))
722 return PTR_ERR(map);
723 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
724
725 if (map->passive.status != PVCALLS_STATUS_BIND) {
726 pvcalls_exit_sock(sock);
727 return -EOPNOTSUPP;
728 }
729
730 spin_lock(&bedata->socket_lock);
731 ret = get_request(bedata, &req_id);
732 if (ret < 0) {
733 spin_unlock(&bedata->socket_lock);
734 pvcalls_exit_sock(sock);
735 return ret;
736 }
737 req = RING_GET_REQUEST(&bedata->ring, req_id);
738 req->req_id = req_id;
739 req->cmd = PVCALLS_LISTEN;
740 req->u.listen.id = (uintptr_t) map;
741 req->u.listen.backlog = backlog;
742
743 bedata->ring.req_prod_pvt++;
744 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
745 spin_unlock(&bedata->socket_lock);
746 if (notify)
747 notify_remote_via_irq(bedata->irq);
748
749 wait_event(bedata->inflight_req,
750 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
751
752 /* read req_id, then the content */
753 smp_rmb();
754 ret = bedata->rsp[req_id].ret;
755 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
756
757 map->passive.status = PVCALLS_STATUS_LISTEN;
758 pvcalls_exit_sock(sock);
759 return ret;
760 }
761
762 int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
763 {
764 struct pvcalls_bedata *bedata;
765 struct sock_mapping *map;
766 struct sock_mapping *map2 = NULL;
767 struct xen_pvcalls_request *req;
768 int notify, req_id, ret, evtchn, nonblock;
769
770 map = pvcalls_enter_sock(sock);
771 if (IS_ERR(map))
772 return PTR_ERR(map);
773 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
774
775 if (map->passive.status != PVCALLS_STATUS_LISTEN) {
776 pvcalls_exit_sock(sock);
777 return -EINVAL;
778 }
779
780 nonblock = flags & SOCK_NONBLOCK;
781 /*
782 * Backend only supports 1 inflight accept request, will return
783 * errors for the others
784 */
785 if (test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
786 (void *)&map->passive.flags)) {
787 req_id = READ_ONCE(map->passive.inflight_req_id);
788 if (req_id != PVCALLS_INVALID_ID &&
789 READ_ONCE(bedata->rsp[req_id].req_id) == req_id) {
790 map2 = map->passive.accept_map;
791 goto received;
792 }
793 if (nonblock) {
794 pvcalls_exit_sock(sock);
795 return -EAGAIN;
796 }
797 if (wait_event_interruptible(map->passive.inflight_accept_req,
798 !test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
799 (void *)&map->passive.flags))) {
800 pvcalls_exit_sock(sock);
801 return -EINTR;
802 }
803 }
804
805 map2 = kzalloc(sizeof(*map2), GFP_KERNEL);
806 if (map2 == NULL) {
807 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
808 (void *)&map->passive.flags);
809 pvcalls_exit_sock(sock);
810 return -ENOMEM;
811 }
812 ret = alloc_active_ring(map2);
813 if (ret < 0) {
814 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
815 (void *)&map->passive.flags);
816 kfree(map2);
817 pvcalls_exit_sock(sock);
818 return ret;
819 }
820 spin_lock(&bedata->socket_lock);
821 ret = get_request(bedata, &req_id);
822 if (ret < 0) {
823 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
824 (void *)&map->passive.flags);
825 spin_unlock(&bedata->socket_lock);
826 free_active_ring(map2);
827 kfree(map2);
828 pvcalls_exit_sock(sock);
829 return ret;
830 }
831
832 ret = create_active(map2, &evtchn);
833 if (ret < 0) {
834 free_active_ring(map2);
835 kfree(map2);
836 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
837 (void *)&map->passive.flags);
838 spin_unlock(&bedata->socket_lock);
839 pvcalls_exit_sock(sock);
840 return ret;
841 }
842 list_add_tail(&map2->list, &bedata->socket_mappings);
843
844 req = RING_GET_REQUEST(&bedata->ring, req_id);
845 req->req_id = req_id;
846 req->cmd = PVCALLS_ACCEPT;
847 req->u.accept.id = (uintptr_t) map;
848 req->u.accept.ref = map2->active.ref;
849 req->u.accept.id_new = (uintptr_t) map2;
850 req->u.accept.evtchn = evtchn;
851 map->passive.accept_map = map2;
852
853 bedata->ring.req_prod_pvt++;
854 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
855 spin_unlock(&bedata->socket_lock);
856 if (notify)
857 notify_remote_via_irq(bedata->irq);
858 /* We could check if we have received a response before returning. */
859 if (nonblock) {
860 WRITE_ONCE(map->passive.inflight_req_id, req_id);
861 pvcalls_exit_sock(sock);
862 return -EAGAIN;
863 }
864
865 if (wait_event_interruptible(bedata->inflight_req,
866 READ_ONCE(bedata->rsp[req_id].req_id) == req_id)) {
867 pvcalls_exit_sock(sock);
868 return -EINTR;
869 }
870 /* read req_id, then the content */
871 smp_rmb();
872
873 received:
874 map2->sock = newsock;
875 newsock->sk = sk_alloc(sock_net(sock->sk), PF_INET, GFP_KERNEL, &pvcalls_proto, false);
876 if (!newsock->sk) {
877 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
878 map->passive.inflight_req_id = PVCALLS_INVALID_ID;
879 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
880 (void *)&map->passive.flags);
881 pvcalls_front_free_map(bedata, map2);
882 pvcalls_exit_sock(sock);
883 return -ENOMEM;
884 }
885 newsock->sk->sk_send_head = (void *)map2;
886
887 ret = bedata->rsp[req_id].ret;
888 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
889 map->passive.inflight_req_id = PVCALLS_INVALID_ID;
890
891 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags);
892 wake_up(&map->passive.inflight_accept_req);
893
894 pvcalls_exit_sock(sock);
895 return ret;
896 }
897
898 static __poll_t pvcalls_front_poll_passive(struct file *file,
899 struct pvcalls_bedata *bedata,
900 struct sock_mapping *map,
901 poll_table *wait)
902 {
903 int notify, req_id, ret;
904 struct xen_pvcalls_request *req;
905
906 if (test_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
907 (void *)&map->passive.flags)) {
908 uint32_t req_id = READ_ONCE(map->passive.inflight_req_id);
909
910 if (req_id != PVCALLS_INVALID_ID &&
911 READ_ONCE(bedata->rsp[req_id].req_id) == req_id)
912 return EPOLLIN | EPOLLRDNORM;
913
914 poll_wait(file, &map->passive.inflight_accept_req, wait);
915 return 0;
916 }
917
918 if (test_and_clear_bit(PVCALLS_FLAG_POLL_RET,
919 (void *)&map->passive.flags))
920 return EPOLLIN | EPOLLRDNORM;
921
922 /*
923 * First check RET, then INFLIGHT. No barriers necessary to
924 * ensure execution ordering because of the conditional
925 * instructions creating control dependencies.
926 */
927
928 if (test_and_set_bit(PVCALLS_FLAG_POLL_INFLIGHT,
929 (void *)&map->passive.flags)) {
930 poll_wait(file, &bedata->inflight_req, wait);
931 return 0;
932 }
933
934 spin_lock(&bedata->socket_lock);
935 ret = get_request(bedata, &req_id);
936 if (ret < 0) {
937 spin_unlock(&bedata->socket_lock);
938 return ret;
939 }
940 req = RING_GET_REQUEST(&bedata->ring, req_id);
941 req->req_id = req_id;
942 req->cmd = PVCALLS_POLL;
943 req->u.poll.id = (uintptr_t) map;
944
945 bedata->ring.req_prod_pvt++;
946 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
947 spin_unlock(&bedata->socket_lock);
948 if (notify)
949 notify_remote_via_irq(bedata->irq);
950
951 poll_wait(file, &bedata->inflight_req, wait);
952 return 0;
953 }
954
955 static __poll_t pvcalls_front_poll_active(struct file *file,
956 struct pvcalls_bedata *bedata,
957 struct sock_mapping *map,
958 poll_table *wait)
959 {
960 __poll_t mask = 0;
961 int32_t in_error, out_error;
962 struct pvcalls_data_intf *intf = map->active.ring;
963
964 out_error = intf->out_error;
965 in_error = intf->in_error;
966
967 poll_wait(file, &map->active.inflight_conn_req, wait);
968 if (pvcalls_front_write_todo(map))
969 mask |= EPOLLOUT | EPOLLWRNORM;
970 if (pvcalls_front_read_todo(map))
971 mask |= EPOLLIN | EPOLLRDNORM;
972 if (in_error != 0 || out_error != 0)
973 mask |= EPOLLERR;
974
975 return mask;
976 }
977
978 __poll_t pvcalls_front_poll(struct file *file, struct socket *sock,
979 poll_table *wait)
980 {
981 struct pvcalls_bedata *bedata;
982 struct sock_mapping *map;
983 __poll_t ret;
984
985 map = pvcalls_enter_sock(sock);
986 if (IS_ERR(map))
987 return EPOLLNVAL;
988 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
989
990 if (map->active_socket)
991 ret = pvcalls_front_poll_active(file, bedata, map, wait);
992 else
993 ret = pvcalls_front_poll_passive(file, bedata, map, wait);
994 pvcalls_exit_sock(sock);
995 return ret;
996 }
997
998 int pvcalls_front_release(struct socket *sock)
999 {
1000 struct pvcalls_bedata *bedata;
1001 struct sock_mapping *map;
1002 int req_id, notify, ret;
1003 struct xen_pvcalls_request *req;
1004
1005 if (sock->sk == NULL)
1006 return 0;
1007
1008 map = pvcalls_enter_sock(sock);
1009 if (IS_ERR(map)) {
1010 if (PTR_ERR(map) == -ENOTCONN)
1011 return -EIO;
1012 else
1013 return 0;
1014 }
1015 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
1016
1017 spin_lock(&bedata->socket_lock);
1018 ret = get_request(bedata, &req_id);
1019 if (ret < 0) {
1020 spin_unlock(&bedata->socket_lock);
1021 pvcalls_exit_sock(sock);
1022 return ret;
1023 }
1024 sock->sk->sk_send_head = NULL;
1025
1026 req = RING_GET_REQUEST(&bedata->ring, req_id);
1027 req->req_id = req_id;
1028 req->cmd = PVCALLS_RELEASE;
1029 req->u.release.id = (uintptr_t)map;
1030
1031 bedata->ring.req_prod_pvt++;
1032 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
1033 spin_unlock(&bedata->socket_lock);
1034 if (notify)
1035 notify_remote_via_irq(bedata->irq);
1036
1037 wait_event(bedata->inflight_req,
1038 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
1039
1040 if (map->active_socket) {
1041 /*
1042 * Set in_error and wake up inflight_conn_req to force
1043 * recvmsg waiters to exit.
1044 */
1045 map->active.ring->in_error = -EBADF;
1046 wake_up_interruptible(&map->active.inflight_conn_req);
1047
1048 /*
1049 * We need to make sure that sendmsg/recvmsg on this socket have
1050 * not started before we've cleared sk_send_head here. The
1051 * easiest way to guarantee this is to see that no pvcalls
1052 * (other than us) is in progress on this socket.
1053 */
1054 while (atomic_read(&map->refcount) > 1)
1055 cpu_relax();
1056
1057 pvcalls_front_free_map(bedata, map);
1058 } else {
1059 wake_up(&bedata->inflight_req);
1060 wake_up(&map->passive.inflight_accept_req);
1061
1062 while (atomic_read(&map->refcount) > 1)
1063 cpu_relax();
1064
1065 spin_lock(&bedata->socket_lock);
1066 list_del(&map->list);
1067 spin_unlock(&bedata->socket_lock);
1068 if (READ_ONCE(map->passive.inflight_req_id) != PVCALLS_INVALID_ID &&
1069 READ_ONCE(map->passive.inflight_req_id) != 0) {
1070 pvcalls_front_free_map(bedata,
1071 map->passive.accept_map);
1072 }
1073 kfree(map);
1074 }
1075 WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID);
1076
1077 pvcalls_exit();
1078 return 0;
1079 }
1080
1081 static const struct xenbus_device_id pvcalls_front_ids[] = {
1082 { "pvcalls" },
1083 { "" }
1084 };
1085
1086 static int pvcalls_front_remove(struct xenbus_device *dev)
1087 {
1088 struct pvcalls_bedata *bedata;
1089 struct sock_mapping *map = NULL, *n;
1090
1091 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
1092 dev_set_drvdata(&dev->dev, NULL);
1093 pvcalls_front_dev = NULL;
1094 if (bedata->irq >= 0)
1095 unbind_from_irqhandler(bedata->irq, dev);
1096
1097 list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
1098 map->sock->sk->sk_send_head = NULL;
1099 if (map->active_socket) {
1100 map->active.ring->in_error = -EBADF;
1101 wake_up_interruptible(&map->active.inflight_conn_req);
1102 }
1103 }
1104
1105 smp_mb();
1106 while (atomic_read(&pvcalls_refcount) > 0)
1107 cpu_relax();
1108 list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
1109 if (map->active_socket) {
1110 /* No need to lock, refcount is 0 */
1111 pvcalls_front_free_map(bedata, map);
1112 } else {
1113 list_del(&map->list);
1114 kfree(map);
1115 }
1116 }
1117 if (bedata->ref != -1)
1118 gnttab_end_foreign_access(bedata->ref, 0, 0);
1119 kfree(bedata->ring.sring);
1120 kfree(bedata);
1121 xenbus_switch_state(dev, XenbusStateClosed);
1122 return 0;
1123 }
1124
1125 static int pvcalls_front_probe(struct xenbus_device *dev,
1126 const struct xenbus_device_id *id)
1127 {
1128 int ret = -ENOMEM, evtchn, i;
1129 unsigned int max_page_order, function_calls, len;
1130 char *versions;
1131 grant_ref_t gref_head = 0;
1132 struct xenbus_transaction xbt;
1133 struct pvcalls_bedata *bedata = NULL;
1134 struct xen_pvcalls_sring *sring;
1135
1136 if (pvcalls_front_dev != NULL) {
1137 dev_err(&dev->dev, "only one PV Calls connection supported\n");
1138 return -EINVAL;
1139 }
1140
1141 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
1142 if (IS_ERR(versions))
1143 return PTR_ERR(versions);
1144 if (!len)
1145 return -EINVAL;
1146 if (strcmp(versions, "1")) {
1147 kfree(versions);
1148 return -EINVAL;
1149 }
1150 kfree(versions);
1151 max_page_order = xenbus_read_unsigned(dev->otherend,
1152 "max-page-order", 0);
1153 if (max_page_order < PVCALLS_RING_ORDER)
1154 return -ENODEV;
1155 function_calls = xenbus_read_unsigned(dev->otherend,
1156 "function-calls", 0);
1157 /* See XENBUS_FUNCTIONS_CALLS in pvcalls.h */
1158 if (function_calls != 1)
1159 return -ENODEV;
1160 pr_info("%s max-page-order is %u\n", __func__, max_page_order);
1161
1162 bedata = kzalloc(sizeof(struct pvcalls_bedata), GFP_KERNEL);
1163 if (!bedata)
1164 return -ENOMEM;
1165
1166 dev_set_drvdata(&dev->dev, bedata);
1167 pvcalls_front_dev = dev;
1168 init_waitqueue_head(&bedata->inflight_req);
1169 INIT_LIST_HEAD(&bedata->socket_mappings);
1170 spin_lock_init(&bedata->socket_lock);
1171 bedata->irq = -1;
1172 bedata->ref = -1;
1173
1174 for (i = 0; i < PVCALLS_NR_RSP_PER_RING; i++)
1175 bedata->rsp[i].req_id = PVCALLS_INVALID_ID;
1176
1177 sring = (struct xen_pvcalls_sring *) __get_free_page(GFP_KERNEL |
1178 __GFP_ZERO);
1179 if (!sring)
1180 goto error;
1181 SHARED_RING_INIT(sring);
1182 FRONT_RING_INIT(&bedata->ring, sring, XEN_PAGE_SIZE);
1183
1184 ret = xenbus_alloc_evtchn(dev, &evtchn);
1185 if (ret)
1186 goto error;
1187
1188 bedata->irq = bind_evtchn_to_irqhandler(evtchn,
1189 pvcalls_front_event_handler,
1190 0, "pvcalls-frontend", dev);
1191 if (bedata->irq < 0) {
1192 ret = bedata->irq;
1193 goto error;
1194 }
1195
1196 ret = gnttab_alloc_grant_references(1, &gref_head);
1197 if (ret < 0)
1198 goto error;
1199 ret = gnttab_claim_grant_reference(&gref_head);
1200 if (ret < 0)
1201 goto error;
1202 bedata->ref = ret;
1203 gnttab_grant_foreign_access_ref(bedata->ref, dev->otherend_id,
1204 virt_to_gfn((void *)sring), 0);
1205
1206 again:
1207 ret = xenbus_transaction_start(&xbt);
1208 if (ret) {
1209 xenbus_dev_fatal(dev, ret, "starting transaction");
1210 goto error;
1211 }
1212 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
1213 if (ret)
1214 goto error_xenbus;
1215 ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", bedata->ref);
1216 if (ret)
1217 goto error_xenbus;
1218 ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
1219 evtchn);
1220 if (ret)
1221 goto error_xenbus;
1222 ret = xenbus_transaction_end(xbt, 0);
1223 if (ret) {
1224 if (ret == -EAGAIN)
1225 goto again;
1226 xenbus_dev_fatal(dev, ret, "completing transaction");
1227 goto error;
1228 }
1229 xenbus_switch_state(dev, XenbusStateInitialised);
1230
1231 return 0;
1232
1233 error_xenbus:
1234 xenbus_transaction_end(xbt, 1);
1235 xenbus_dev_fatal(dev, ret, "writing xenstore");
1236 error:
1237 pvcalls_front_remove(dev);
1238 return ret;
1239 }
1240
1241 static void pvcalls_front_changed(struct xenbus_device *dev,
1242 enum xenbus_state backend_state)
1243 {
1244 switch (backend_state) {
1245 case XenbusStateReconfiguring:
1246 case XenbusStateReconfigured:
1247 case XenbusStateInitialising:
1248 case XenbusStateInitialised:
1249 case XenbusStateUnknown:
1250 break;
1251
1252 case XenbusStateInitWait:
1253 break;
1254
1255 case XenbusStateConnected:
1256 xenbus_switch_state(dev, XenbusStateConnected);
1257 break;
1258
1259 case XenbusStateClosed:
1260 if (dev->state == XenbusStateClosed)
1261 break;
1262 /* Missed the backend's CLOSING state */
1263 /* fall through */
1264 case XenbusStateClosing:
1265 xenbus_frontend_closed(dev);
1266 break;
1267 }
1268 }
1269
1270 static struct xenbus_driver pvcalls_front_driver = {
1271 .ids = pvcalls_front_ids,
1272 .probe = pvcalls_front_probe,
1273 .remove = pvcalls_front_remove,
1274 .otherend_changed = pvcalls_front_changed,
1275 };
1276
1277 static int __init pvcalls_frontend_init(void)
1278 {
1279 if (!xen_domain())
1280 return -ENODEV;
1281
1282 pr_info("Initialising Xen pvcalls frontend driver\n");
1283
1284 return xenbus_register_frontend(&pvcalls_front_driver);
1285 }
1286
1287 module_init(pvcalls_frontend_init);
1288
1289 MODULE_DESCRIPTION("Xen PV Calls frontend driver");
1290 MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>");
1291 MODULE_LICENSE("GPL");
Linux with added FPC-III support