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
34static struct proto pvcalls_proto = {
35 .name = "PVCalls",
36 .owner = THIS_MODULE,
37 .obj_size = sizeof(struct sock),
38};
39
40struct pvcalls_bedata {
41 struct xen_pvcalls_front_ring ring;
42 grant_ref_t ref;
43 int irq;
44
45 struct list_head socket_mappings;
46 spinlock_t socket_lock;
47
48 wait_queue_head_t inflight_req;
49 struct xen_pvcalls_response rsp[PVCALLS_NR_RSP_PER_RING];
50};
51/* Only one front/back connection supported. */
52static struct xenbus_device *pvcalls_front_dev;
53static atomic_t pvcalls_refcount;
54
55/* first increment refcount, then proceed */
56#define pvcalls_enter() { \
57 atomic_inc(&pvcalls_refcount); \
58}
59
60/* first complete other operations, then decrement refcount */
61#define pvcalls_exit() { \
62 atomic_dec(&pvcalls_refcount); \
63}
64
65struct sock_mapping {
66 bool active_socket;
67 struct list_head list;
68 struct socket *sock;
69 atomic_t refcount;
70 union {
71 struct {
72 int irq;
73 grant_ref_t ref;
74 struct pvcalls_data_intf *ring;
75 struct pvcalls_data data;
76 struct mutex in_mutex;
77 struct mutex out_mutex;
78
79 wait_queue_head_t inflight_conn_req;
80 } active;
81 struct {
82 /*
83 * Socket status, needs to be 64-bit aligned due to the
84 * test_and_* functions which have this requirement on arm64.
85 */
86#define PVCALLS_STATUS_UNINITALIZED 0
87#define PVCALLS_STATUS_BIND 1
88#define PVCALLS_STATUS_LISTEN 2
89 uint8_t status __attribute__((aligned(8)));
90 /*
91 * Internal state-machine flags.
92 * Only one accept operation can be inflight for a socket.
93 * Only one poll operation can be inflight for a given socket.
94 * flags needs to be 64-bit aligned due to the test_and_*
95 * functions which have this requirement on arm64.
96 */
97#define PVCALLS_FLAG_ACCEPT_INFLIGHT 0
98#define PVCALLS_FLAG_POLL_INFLIGHT 1
99#define PVCALLS_FLAG_POLL_RET 2
100 uint8_t flags __attribute__((aligned(8)));
101 uint32_t inflight_req_id;
102 struct sock_mapping *accept_map;
103 wait_queue_head_t inflight_accept_req;
104 } passive;
105 };
106};
107
108static inline struct sock_mapping *pvcalls_enter_sock(struct socket *sock)
109{
110 struct sock_mapping *map;
111
112 if (!pvcalls_front_dev ||
113 dev_get_drvdata(&pvcalls_front_dev->dev) == NULL)
114 return ERR_PTR(-ENOTCONN);
115
116 map = (struct sock_mapping *)sock->sk->sk_send_head;
117 if (map == NULL)
118 return ERR_PTR(-ENOTSOCK);
119
120 pvcalls_enter();
121 atomic_inc(&map->refcount);
122 return map;
123}
124
125static inline void pvcalls_exit_sock(struct socket *sock)
126{
127 struct sock_mapping *map;
128
129 map = (struct sock_mapping *)sock->sk->sk_send_head;
130 atomic_dec(&map->refcount);
131 pvcalls_exit();
132}
133
134static inline int get_request(struct pvcalls_bedata *bedata, int *req_id)
135{
136 *req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1);
137 if (RING_FULL(&bedata->ring) ||
138 bedata->rsp[*req_id].req_id != PVCALLS_INVALID_ID)
139 return -EAGAIN;
140 return 0;
141}
142
143static bool pvcalls_front_write_todo(struct sock_mapping *map)
144{
145 struct pvcalls_data_intf *intf = map->active.ring;
146 RING_IDX cons, prod, size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
147 int32_t error;
148
149 error = intf->out_error;
150 if (error == -ENOTCONN)
151 return false;
152 if (error != 0)
153 return true;
154
155 cons = intf->out_cons;
156 prod = intf->out_prod;
157 return !!(size - pvcalls_queued(prod, cons, size));
158}
159
160static bool pvcalls_front_read_todo(struct sock_mapping *map)
161{
162 struct pvcalls_data_intf *intf = map->active.ring;
163 RING_IDX cons, prod;
164 int32_t error;
165
166 cons = intf->in_cons;
167 prod = intf->in_prod;
168 error = intf->in_error;
169 return (error != 0 ||
170 pvcalls_queued(prod, cons,
171 XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER)) != 0);
172}
173
174static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
175{
176 struct xenbus_device *dev = dev_id;
177 struct pvcalls_bedata *bedata;
178 struct xen_pvcalls_response *rsp;
179 uint8_t *src, *dst;
180 int req_id = 0, more = 0, done = 0;
181
182 if (dev == NULL)
183 return IRQ_HANDLED;
184
185 pvcalls_enter();
186 bedata = dev_get_drvdata(&dev->dev);
187 if (bedata == NULL) {
188 pvcalls_exit();
189 return IRQ_HANDLED;
190 }
191
192again:
193 while (RING_HAS_UNCONSUMED_RESPONSES(&bedata->ring)) {
194 rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons);
195
196 req_id = rsp->req_id;
197 if (rsp->cmd == PVCALLS_POLL) {
198 struct sock_mapping *map = (struct sock_mapping *)(uintptr_t)
199 rsp->u.poll.id;
200
201 clear_bit(PVCALLS_FLAG_POLL_INFLIGHT,
202 (void *)&map->passive.flags);
203 /*
204 * clear INFLIGHT, then set RET. It pairs with
205 * the checks at the beginning of
206 * pvcalls_front_poll_passive.
207 */
208 smp_wmb();
209 set_bit(PVCALLS_FLAG_POLL_RET,
210 (void *)&map->passive.flags);
211 } else {
212 dst = (uint8_t *)&bedata->rsp[req_id] +
213 sizeof(rsp->req_id);
214 src = (uint8_t *)rsp + sizeof(rsp->req_id);
215 memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id));
216 /*
217 * First copy the rest of the data, then req_id. It is
218 * paired with the barrier when accessing bedata->rsp.
219 */
220 smp_wmb();
221 bedata->rsp[req_id].req_id = req_id;
222 }
223
224 done = 1;
225 bedata->ring.rsp_cons++;
226 }
227
228 RING_FINAL_CHECK_FOR_RESPONSES(&bedata->ring, more);
229 if (more)
230 goto again;
231 if (done)
232 wake_up(&bedata->inflight_req);
233 pvcalls_exit();
234 return IRQ_HANDLED;
235}
236
237static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
238 struct sock_mapping *map)
239{
240 int i;
241
242 unbind_from_irqhandler(map->active.irq, map);
243
244 spin_lock(&bedata->socket_lock);
245 if (!list_empty(&map->list))
246 list_del_init(&map->list);
247 spin_unlock(&bedata->socket_lock);
248
249 for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
250 gnttab_end_foreign_access(map->active.ring->ref[i], 0, 0);
251 gnttab_end_foreign_access(map->active.ref, 0, 0);
252 free_page((unsigned long)map->active.ring);
253
254 kfree(map);
255}
256
257static irqreturn_t pvcalls_front_conn_handler(int irq, void *sock_map)
258{
259 struct sock_mapping *map = sock_map;
260
261 if (map == NULL)
262 return IRQ_HANDLED;
263
264 wake_up_interruptible(&map->active.inflight_conn_req);
265
266 return IRQ_HANDLED;
267}
268
269int pvcalls_front_socket(struct socket *sock)
270{
271 struct pvcalls_bedata *bedata;
272 struct sock_mapping *map = NULL;
273 struct xen_pvcalls_request *req;
274 int notify, req_id, ret;
275
276 /*
277 * PVCalls only supports domain AF_INET,
278 * type SOCK_STREAM and protocol 0 sockets for now.
279 *
280 * Check socket type here, AF_INET and protocol checks are done
281 * by the caller.
282 */
283 if (sock->type != SOCK_STREAM)
284 return -EOPNOTSUPP;
285
286 pvcalls_enter();
287 if (!pvcalls_front_dev) {
288 pvcalls_exit();
289 return -EACCES;
290 }
291 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
292
293 map = kzalloc(sizeof(*map), GFP_KERNEL);
294 if (map == NULL) {
295 pvcalls_exit();
296 return -ENOMEM;
297 }
298
299 spin_lock(&bedata->socket_lock);
300
301 ret = get_request(bedata, &req_id);
302 if (ret < 0) {
303 kfree(map);
304 spin_unlock(&bedata->socket_lock);
305 pvcalls_exit();
306 return ret;
307 }
308
309 /*
310 * sock->sk->sk_send_head is not used for ip sockets: reuse the
311 * field to store a pointer to the struct sock_mapping
312 * corresponding to the socket. This way, we can easily get the
313 * struct sock_mapping from the struct socket.
314 */
315 sock->sk->sk_send_head = (void *)map;
316 list_add_tail(&map->list, &bedata->socket_mappings);
317
318 req = RING_GET_REQUEST(&bedata->ring, req_id);
319 req->req_id = req_id;
320 req->cmd = PVCALLS_SOCKET;
321 req->u.socket.id = (uintptr_t) map;
322 req->u.socket.domain = AF_INET;
323 req->u.socket.type = SOCK_STREAM;
324 req->u.socket.protocol = IPPROTO_IP;
325
326 bedata->ring.req_prod_pvt++;
327 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
328 spin_unlock(&bedata->socket_lock);
329 if (notify)
330 notify_remote_via_irq(bedata->irq);
331
332 wait_event(bedata->inflight_req,
333 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
334
335 /* read req_id, then the content */
336 smp_rmb();
337 ret = bedata->rsp[req_id].ret;
338 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
339
340 pvcalls_exit();
341 return ret;
342}
343
344static void free_active_ring(struct sock_mapping *map)
345{
346 if (!map->active.ring)
347 return;
348
349 free_pages((unsigned long)map->active.data.in,
350 map->active.ring->ring_order);
351 free_page((unsigned long)map->active.ring);
352}
353
354static int alloc_active_ring(struct sock_mapping *map)
355{
356 void *bytes;
357
358 map->active.ring = (struct pvcalls_data_intf *)
359 get_zeroed_page(GFP_KERNEL);
360 if (!map->active.ring)
361 goto out;
362
363 map->active.ring->ring_order = PVCALLS_RING_ORDER;
364 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
365 PVCALLS_RING_ORDER);
366 if (!bytes)
367 goto out;
368
369 map->active.data.in = bytes;
370 map->active.data.out = bytes +
371 XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
372
373 return 0;
374
375out:
376 free_active_ring(map);
377 return -ENOMEM;
378}
379
380static int create_active(struct sock_mapping *map, int *evtchn)
381{
382 void *bytes;
383 int ret = -ENOMEM, irq = -1, i;
384
385 *evtchn = -1;
386 init_waitqueue_head(&map->active.inflight_conn_req);
387
388 bytes = map->active.data.in;
389 for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
390 map->active.ring->ref[i] = gnttab_grant_foreign_access(
391 pvcalls_front_dev->otherend_id,
392 pfn_to_gfn(virt_to_pfn(bytes) + i), 0);
393
394 map->active.ref = gnttab_grant_foreign_access(
395 pvcalls_front_dev->otherend_id,
396 pfn_to_gfn(virt_to_pfn((void *)map->active.ring)), 0);
397
398 ret = xenbus_alloc_evtchn(pvcalls_front_dev, evtchn);
399 if (ret)
400 goto out_error;
401 irq = bind_evtchn_to_irqhandler(*evtchn, pvcalls_front_conn_handler,
402 0, "pvcalls-frontend", map);
403 if (irq < 0) {
404 ret = irq;
405 goto out_error;
406 }
407
408 map->active.irq = irq;
409 map->active_socket = true;
410 mutex_init(&map->active.in_mutex);
411 mutex_init(&map->active.out_mutex);
412
413 return 0;
414
415out_error:
416 if (*evtchn >= 0)
417 xenbus_free_evtchn(pvcalls_front_dev, *evtchn);
418 return ret;
419}
420
421int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
422 int addr_len, int flags)
423{
424 struct pvcalls_bedata *bedata;
425 struct sock_mapping *map = NULL;
426 struct xen_pvcalls_request *req;
427 int notify, req_id, ret, evtchn;
428
429 if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
430 return -EOPNOTSUPP;
431
432 map = pvcalls_enter_sock(sock);
433 if (IS_ERR(map))
434 return PTR_ERR(map);
435
436 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
437 ret = alloc_active_ring(map);
438 if (ret < 0) {
439 pvcalls_exit_sock(sock);
440 return ret;
441 }
442
443 spin_lock(&bedata->socket_lock);
444 ret = get_request(bedata, &req_id);
445 if (ret < 0) {
446 spin_unlock(&bedata->socket_lock);
447 free_active_ring(map);
448 pvcalls_exit_sock(sock);
449 return ret;
450 }
451 ret = create_active(map, &evtchn);
452 if (ret < 0) {
453 spin_unlock(&bedata->socket_lock);
454 free_active_ring(map);
455 pvcalls_exit_sock(sock);
456 return ret;
457 }
458
459 req = RING_GET_REQUEST(&bedata->ring, req_id);
460 req->req_id = req_id;
461 req->cmd = PVCALLS_CONNECT;
462 req->u.connect.id = (uintptr_t)map;
463 req->u.connect.len = addr_len;
464 req->u.connect.flags = flags;
465 req->u.connect.ref = map->active.ref;
466 req->u.connect.evtchn = evtchn;
467 memcpy(req->u.connect.addr, addr, sizeof(*addr));
468
469 map->sock = sock;
470
471 bedata->ring.req_prod_pvt++;
472 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
473 spin_unlock(&bedata->socket_lock);
474
475 if (notify)
476 notify_remote_via_irq(bedata->irq);
477
478 wait_event(bedata->inflight_req,
479 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
480
481 /* read req_id, then the content */
482 smp_rmb();
483 ret = bedata->rsp[req_id].ret;
484 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
485 pvcalls_exit_sock(sock);
486 return ret;
487}
488
489static int __write_ring(struct pvcalls_data_intf *intf,
490 struct pvcalls_data *data,
491 struct iov_iter *msg_iter,
492 int len)
493{
494 RING_IDX cons, prod, size, masked_prod, masked_cons;
495 RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
496 int32_t error;
497
498 error = intf->out_error;
499 if (error < 0)
500 return error;
501 cons = intf->out_cons;
502 prod = intf->out_prod;
503 /* read indexes before continuing */
504 virt_mb();
505
506 size = pvcalls_queued(prod, cons, array_size);
507 if (size > array_size)
508 return -EINVAL;
509 if (size == array_size)
510 return 0;
511 if (len > array_size - size)
512 len = array_size - size;
513
514 masked_prod = pvcalls_mask(prod, array_size);
515 masked_cons = pvcalls_mask(cons, array_size);
516
517 if (masked_prod < masked_cons) {
518 len = copy_from_iter(data->out + masked_prod, len, msg_iter);
519 } else {
520 if (len > array_size - masked_prod) {
521 int ret = copy_from_iter(data->out + masked_prod,
522 array_size - masked_prod, msg_iter);
523 if (ret != array_size - masked_prod) {
524 len = ret;
525 goto out;
526 }
527 len = ret + copy_from_iter(data->out, len - ret, msg_iter);
528 } else {
529 len = copy_from_iter(data->out + masked_prod, len, msg_iter);
530 }
531 }
532out:
533 /* write to ring before updating pointer */
534 virt_wmb();
535 intf->out_prod += len;
536
537 return len;
538}
539
540int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg,
541 size_t len)
542{
543 struct pvcalls_bedata *bedata;
544 struct sock_mapping *map;
545 int sent, tot_sent = 0;
546 int count = 0, flags;
547
548 flags = msg->msg_flags;
549 if (flags & (MSG_CONFIRM|MSG_DONTROUTE|MSG_EOR|MSG_OOB))
550 return -EOPNOTSUPP;
551
552 map = pvcalls_enter_sock(sock);
553 if (IS_ERR(map))
554 return PTR_ERR(map);
555 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
556
557 mutex_lock(&map->active.out_mutex);
558 if ((flags & MSG_DONTWAIT) && !pvcalls_front_write_todo(map)) {
559 mutex_unlock(&map->active.out_mutex);
560 pvcalls_exit_sock(sock);
561 return -EAGAIN;
562 }
563 if (len > INT_MAX)
564 len = INT_MAX;
565
566again:
567 count++;
568 sent = __write_ring(map->active.ring,
569 &map->active.data, &msg->msg_iter,
570 len);
571 if (sent > 0) {
572 len -= sent;
573 tot_sent += sent;
574 notify_remote_via_irq(map->active.irq);
575 }
576 if (sent >= 0 && len > 0 && count < PVCALLS_FRONT_MAX_SPIN)
577 goto again;
578 if (sent < 0)
579 tot_sent = sent;
580
581 mutex_unlock(&map->active.out_mutex);
582 pvcalls_exit_sock(sock);
583 return tot_sent;
584}
585
586static int __read_ring(struct pvcalls_data_intf *intf,
587 struct pvcalls_data *data,
588 struct iov_iter *msg_iter,
589 size_t len, int flags)
590{
591 RING_IDX cons, prod, size, masked_prod, masked_cons;
592 RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
593 int32_t error;
594
595 cons = intf->in_cons;
596 prod = intf->in_prod;
597 error = intf->in_error;
598 /* get pointers before reading from the ring */
599 virt_rmb();
600
601 size = pvcalls_queued(prod, cons, array_size);
602 masked_prod = pvcalls_mask(prod, array_size);
603 masked_cons = pvcalls_mask(cons, array_size);
604
605 if (size == 0)
606 return error ?: size;
607
608 if (len > size)
609 len = size;
610
611 if (masked_prod > masked_cons) {
612 len = copy_to_iter(data->in + masked_cons, len, msg_iter);
613 } else {
614 if (len > (array_size - masked_cons)) {
615 int ret = copy_to_iter(data->in + masked_cons,
616 array_size - masked_cons, msg_iter);
617 if (ret != array_size - masked_cons) {
618 len = ret;
619 goto out;
620 }
621 len = ret + copy_to_iter(data->in, len - ret, msg_iter);
622 } else {
623 len = copy_to_iter(data->in + masked_cons, len, msg_iter);
624 }
625 }
626out:
627 /* read data from the ring before increasing the index */
628 virt_mb();
629 if (!(flags & MSG_PEEK))
630 intf->in_cons += len;
631
632 return len;
633}
634
635int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
636 int flags)
637{
638 struct pvcalls_bedata *bedata;
639 int ret;
640 struct sock_mapping *map;
641
642 if (flags & (MSG_CMSG_CLOEXEC|MSG_ERRQUEUE|MSG_OOB|MSG_TRUNC))
643 return -EOPNOTSUPP;
644
645 map = pvcalls_enter_sock(sock);
646 if (IS_ERR(map))
647 return PTR_ERR(map);
648 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
649
650 mutex_lock(&map->active.in_mutex);
651 if (len > XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER))
652 len = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
653
654 while (!(flags & MSG_DONTWAIT) && !pvcalls_front_read_todo(map)) {
655 wait_event_interruptible(map->active.inflight_conn_req,
656 pvcalls_front_read_todo(map));
657 }
658 ret = __read_ring(map->active.ring, &map->active.data,
659 &msg->msg_iter, len, flags);
660
661 if (ret > 0)
662 notify_remote_via_irq(map->active.irq);
663 if (ret == 0)
664 ret = (flags & MSG_DONTWAIT) ? -EAGAIN : 0;
665 if (ret == -ENOTCONN)
666 ret = 0;
667
668 mutex_unlock(&map->active.in_mutex);
669 pvcalls_exit_sock(sock);
670 return ret;
671}
672
673int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
674{
675 struct pvcalls_bedata *bedata;
676 struct sock_mapping *map = NULL;
677 struct xen_pvcalls_request *req;
678 int notify, req_id, ret;
679
680 if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
681 return -EOPNOTSUPP;
682
683 map = pvcalls_enter_sock(sock);
684 if (IS_ERR(map))
685 return PTR_ERR(map);
686 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
687
688 spin_lock(&bedata->socket_lock);
689 ret = get_request(bedata, &req_id);
690 if (ret < 0) {
691 spin_unlock(&bedata->socket_lock);
692 pvcalls_exit_sock(sock);
693 return ret;
694 }
695 req = RING_GET_REQUEST(&bedata->ring, req_id);
696 req->req_id = req_id;
697 map->sock = sock;
698 req->cmd = PVCALLS_BIND;
699 req->u.bind.id = (uintptr_t)map;
700 memcpy(req->u.bind.addr, addr, sizeof(*addr));
701 req->u.bind.len = addr_len;
702
703 init_waitqueue_head(&map->passive.inflight_accept_req);
704
705 map->active_socket = false;
706
707 bedata->ring.req_prod_pvt++;
708 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
709 spin_unlock(&bedata->socket_lock);
710 if (notify)
711 notify_remote_via_irq(bedata->irq);
712
713 wait_event(bedata->inflight_req,
714 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
715
716 /* read req_id, then the content */
717 smp_rmb();
718 ret = bedata->rsp[req_id].ret;
719 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
720
721 map->passive.status = PVCALLS_STATUS_BIND;
722 pvcalls_exit_sock(sock);
723 return 0;
724}
725
726int pvcalls_front_listen(struct socket *sock, int backlog)
727{
728 struct pvcalls_bedata *bedata;
729 struct sock_mapping *map;
730 struct xen_pvcalls_request *req;
731 int notify, req_id, ret;
732
733 map = pvcalls_enter_sock(sock);
734 if (IS_ERR(map))
735 return PTR_ERR(map);
736 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
737
738 if (map->passive.status != PVCALLS_STATUS_BIND) {
739 pvcalls_exit_sock(sock);
740 return -EOPNOTSUPP;
741 }
742
743 spin_lock(&bedata->socket_lock);
744 ret = get_request(bedata, &req_id);
745 if (ret < 0) {
746 spin_unlock(&bedata->socket_lock);
747 pvcalls_exit_sock(sock);
748 return ret;
749 }
750 req = RING_GET_REQUEST(&bedata->ring, req_id);
751 req->req_id = req_id;
752 req->cmd = PVCALLS_LISTEN;
753 req->u.listen.id = (uintptr_t) map;
754 req->u.listen.backlog = backlog;
755
756 bedata->ring.req_prod_pvt++;
757 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
758 spin_unlock(&bedata->socket_lock);
759 if (notify)
760 notify_remote_via_irq(bedata->irq);
761
762 wait_event(bedata->inflight_req,
763 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
764
765 /* read req_id, then the content */
766 smp_rmb();
767 ret = bedata->rsp[req_id].ret;
768 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
769
770 map->passive.status = PVCALLS_STATUS_LISTEN;
771 pvcalls_exit_sock(sock);
772 return ret;
773}
774
775int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
776{
777 struct pvcalls_bedata *bedata;
778 struct sock_mapping *map;
779 struct sock_mapping *map2 = NULL;
780 struct xen_pvcalls_request *req;
781 int notify, req_id, ret, evtchn, nonblock;
782
783 map = pvcalls_enter_sock(sock);
784 if (IS_ERR(map))
785 return PTR_ERR(map);
786 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
787
788 if (map->passive.status != PVCALLS_STATUS_LISTEN) {
789 pvcalls_exit_sock(sock);
790 return -EINVAL;
791 }
792
793 nonblock = flags & SOCK_NONBLOCK;
794 /*
795 * Backend only supports 1 inflight accept request, will return
796 * errors for the others
797 */
798 if (test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
799 (void *)&map->passive.flags)) {
800 req_id = READ_ONCE(map->passive.inflight_req_id);
801 if (req_id != PVCALLS_INVALID_ID &&
802 READ_ONCE(bedata->rsp[req_id].req_id) == req_id) {
803 map2 = map->passive.accept_map;
804 goto received;
805 }
806 if (nonblock) {
807 pvcalls_exit_sock(sock);
808 return -EAGAIN;
809 }
810 if (wait_event_interruptible(map->passive.inflight_accept_req,
811 !test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
812 (void *)&map->passive.flags))) {
813 pvcalls_exit_sock(sock);
814 return -EINTR;
815 }
816 }
817
818 map2 = kzalloc(sizeof(*map2), GFP_KERNEL);
819 if (map2 == NULL) {
820 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
821 (void *)&map->passive.flags);
822 pvcalls_exit_sock(sock);
823 return -ENOMEM;
824 }
825 ret = alloc_active_ring(map2);
826 if (ret < 0) {
827 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
828 (void *)&map->passive.flags);
829 kfree(map2);
830 pvcalls_exit_sock(sock);
831 return ret;
832 }
833 spin_lock(&bedata->socket_lock);
834 ret = get_request(bedata, &req_id);
835 if (ret < 0) {
836 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
837 (void *)&map->passive.flags);
838 spin_unlock(&bedata->socket_lock);
839 free_active_ring(map2);
840 kfree(map2);
841 pvcalls_exit_sock(sock);
842 return ret;
843 }
844
845 ret = create_active(map2, &evtchn);
846 if (ret < 0) {
847 free_active_ring(map2);
848 kfree(map2);
849 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
850 (void *)&map->passive.flags);
851 spin_unlock(&bedata->socket_lock);
852 pvcalls_exit_sock(sock);
853 return ret;
854 }
855 list_add_tail(&map2->list, &bedata->socket_mappings);
856
857 req = RING_GET_REQUEST(&bedata->ring, req_id);
858 req->req_id = req_id;
859 req->cmd = PVCALLS_ACCEPT;
860 req->u.accept.id = (uintptr_t) map;
861 req->u.accept.ref = map2->active.ref;
862 req->u.accept.id_new = (uintptr_t) map2;
863 req->u.accept.evtchn = evtchn;
864 map->passive.accept_map = map2;
865
866 bedata->ring.req_prod_pvt++;
867 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
868 spin_unlock(&bedata->socket_lock);
869 if (notify)
870 notify_remote_via_irq(bedata->irq);
871 /* We could check if we have received a response before returning. */
872 if (nonblock) {
873 WRITE_ONCE(map->passive.inflight_req_id, req_id);
874 pvcalls_exit_sock(sock);
875 return -EAGAIN;
876 }
877
878 if (wait_event_interruptible(bedata->inflight_req,
879 READ_ONCE(bedata->rsp[req_id].req_id) == req_id)) {
880 pvcalls_exit_sock(sock);
881 return -EINTR;
882 }
883 /* read req_id, then the content */
884 smp_rmb();
885
886received:
887 map2->sock = newsock;
888 newsock->sk = sk_alloc(sock_net(sock->sk), PF_INET, GFP_KERNEL, &pvcalls_proto, false);
889 if (!newsock->sk) {
890 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
891 map->passive.inflight_req_id = PVCALLS_INVALID_ID;
892 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
893 (void *)&map->passive.flags);
894 pvcalls_front_free_map(bedata, map2);
895 pvcalls_exit_sock(sock);
896 return -ENOMEM;
897 }
898 newsock->sk->sk_send_head = (void *)map2;
899
900 ret = bedata->rsp[req_id].ret;
901 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
902 map->passive.inflight_req_id = PVCALLS_INVALID_ID;
903
904 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags);
905 wake_up(&map->passive.inflight_accept_req);
906
907 pvcalls_exit_sock(sock);
908 return ret;
909}
910
911static __poll_t pvcalls_front_poll_passive(struct file *file,
912 struct pvcalls_bedata *bedata,
913 struct sock_mapping *map,
914 poll_table *wait)
915{
916 int notify, req_id, ret;
917 struct xen_pvcalls_request *req;
918
919 if (test_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
920 (void *)&map->passive.flags)) {
921 uint32_t req_id = READ_ONCE(map->passive.inflight_req_id);
922
923 if (req_id != PVCALLS_INVALID_ID &&
924 READ_ONCE(bedata->rsp[req_id].req_id) == req_id)
925 return EPOLLIN | EPOLLRDNORM;
926
927 poll_wait(file, &map->passive.inflight_accept_req, wait);
928 return 0;
929 }
930
931 if (test_and_clear_bit(PVCALLS_FLAG_POLL_RET,
932 (void *)&map->passive.flags))
933 return EPOLLIN | EPOLLRDNORM;
934
935 /*
936 * First check RET, then INFLIGHT. No barriers necessary to
937 * ensure execution ordering because of the conditional
938 * instructions creating control dependencies.
939 */
940
941 if (test_and_set_bit(PVCALLS_FLAG_POLL_INFLIGHT,
942 (void *)&map->passive.flags)) {
943 poll_wait(file, &bedata->inflight_req, wait);
944 return 0;
945 }
946
947 spin_lock(&bedata->socket_lock);
948 ret = get_request(bedata, &req_id);
949 if (ret < 0) {
950 spin_unlock(&bedata->socket_lock);
951 return ret;
952 }
953 req = RING_GET_REQUEST(&bedata->ring, req_id);
954 req->req_id = req_id;
955 req->cmd = PVCALLS_POLL;
956 req->u.poll.id = (uintptr_t) map;
957
958 bedata->ring.req_prod_pvt++;
959 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
960 spin_unlock(&bedata->socket_lock);
961 if (notify)
962 notify_remote_via_irq(bedata->irq);
963
964 poll_wait(file, &bedata->inflight_req, wait);
965 return 0;
966}
967
968static __poll_t pvcalls_front_poll_active(struct file *file,
969 struct pvcalls_bedata *bedata,
970 struct sock_mapping *map,
971 poll_table *wait)
972{
973 __poll_t mask = 0;
974 int32_t in_error, out_error;
975 struct pvcalls_data_intf *intf = map->active.ring;
976
977 out_error = intf->out_error;
978 in_error = intf->in_error;
979
980 poll_wait(file, &map->active.inflight_conn_req, wait);
981 if (pvcalls_front_write_todo(map))
982 mask |= EPOLLOUT | EPOLLWRNORM;
983 if (pvcalls_front_read_todo(map))
984 mask |= EPOLLIN | EPOLLRDNORM;
985 if (in_error != 0 || out_error != 0)
986 mask |= EPOLLERR;
987
988 return mask;
989}
990
991__poll_t pvcalls_front_poll(struct file *file, struct socket *sock,
992 poll_table *wait)
993{
994 struct pvcalls_bedata *bedata;
995 struct sock_mapping *map;
996 __poll_t ret;
997
998 map = pvcalls_enter_sock(sock);
999 if (IS_ERR(map))
1000 return EPOLLNVAL;
1001 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
1002
1003 if (map->active_socket)
1004 ret = pvcalls_front_poll_active(file, bedata, map, wait);
1005 else
1006 ret = pvcalls_front_poll_passive(file, bedata, map, wait);
1007 pvcalls_exit_sock(sock);
1008 return ret;
1009}
1010
1011int pvcalls_front_release(struct socket *sock)
1012{
1013 struct pvcalls_bedata *bedata;
1014 struct sock_mapping *map;
1015 int req_id, notify, ret;
1016 struct xen_pvcalls_request *req;
1017
1018 if (sock->sk == NULL)
1019 return 0;
1020
1021 map = pvcalls_enter_sock(sock);
1022 if (IS_ERR(map)) {
1023 if (PTR_ERR(map) == -ENOTCONN)
1024 return -EIO;
1025 else
1026 return 0;
1027 }
1028 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
1029
1030 spin_lock(&bedata->socket_lock);
1031 ret = get_request(bedata, &req_id);
1032 if (ret < 0) {
1033 spin_unlock(&bedata->socket_lock);
1034 pvcalls_exit_sock(sock);
1035 return ret;
1036 }
1037 sock->sk->sk_send_head = NULL;
1038
1039 req = RING_GET_REQUEST(&bedata->ring, req_id);
1040 req->req_id = req_id;
1041 req->cmd = PVCALLS_RELEASE;
1042 req->u.release.id = (uintptr_t)map;
1043
1044 bedata->ring.req_prod_pvt++;
1045 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
1046 spin_unlock(&bedata->socket_lock);
1047 if (notify)
1048 notify_remote_via_irq(bedata->irq);
1049
1050 wait_event(bedata->inflight_req,
1051 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
1052
1053 if (map->active_socket) {
1054 /*
1055 * Set in_error and wake up inflight_conn_req to force
1056 * recvmsg waiters to exit.
1057 */
1058 map->active.ring->in_error = -EBADF;
1059 wake_up_interruptible(&map->active.inflight_conn_req);
1060
1061 /*
1062 * We need to make sure that sendmsg/recvmsg on this socket have
1063 * not started before we've cleared sk_send_head here. The
1064 * easiest way to guarantee this is to see that no pvcalls
1065 * (other than us) is in progress on this socket.
1066 */
1067 while (atomic_read(&map->refcount) > 1)
1068 cpu_relax();
1069
1070 pvcalls_front_free_map(bedata, map);
1071 } else {
1072 wake_up(&bedata->inflight_req);
1073 wake_up(&map->passive.inflight_accept_req);
1074
1075 while (atomic_read(&map->refcount) > 1)
1076 cpu_relax();
1077
1078 spin_lock(&bedata->socket_lock);
1079 list_del(&map->list);
1080 spin_unlock(&bedata->socket_lock);
1081 if (READ_ONCE(map->passive.inflight_req_id) != PVCALLS_INVALID_ID &&
1082 READ_ONCE(map->passive.inflight_req_id) != 0) {
1083 pvcalls_front_free_map(bedata,
1084 map->passive.accept_map);
1085 }
1086 kfree(map);
1087 }
1088 WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID);
1089
1090 pvcalls_exit();
1091 return 0;
1092}
1093
1094static const struct xenbus_device_id pvcalls_front_ids[] = {
1095 { "pvcalls" },
1096 { "" }
1097};
1098
1099static int pvcalls_front_remove(struct xenbus_device *dev)
1100{
1101 struct pvcalls_bedata *bedata;
1102 struct sock_mapping *map = NULL, *n;
1103
1104 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
1105 dev_set_drvdata(&dev->dev, NULL);
1106 pvcalls_front_dev = NULL;
1107 if (bedata->irq >= 0)
1108 unbind_from_irqhandler(bedata->irq, dev);
1109
1110 list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
1111 map->sock->sk->sk_send_head = NULL;
1112 if (map->active_socket) {
1113 map->active.ring->in_error = -EBADF;
1114 wake_up_interruptible(&map->active.inflight_conn_req);
1115 }
1116 }
1117
1118 smp_mb();
1119 while (atomic_read(&pvcalls_refcount) > 0)
1120 cpu_relax();
1121 list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
1122 if (map->active_socket) {
1123 /* No need to lock, refcount is 0 */
1124 pvcalls_front_free_map(bedata, map);
1125 } else {
1126 list_del(&map->list);
1127 kfree(map);
1128 }
1129 }
1130 if (bedata->ref != -1)
1131 gnttab_end_foreign_access(bedata->ref, 0, 0);
1132 kfree(bedata->ring.sring);
1133 kfree(bedata);
1134 xenbus_switch_state(dev, XenbusStateClosed);
1135 return 0;
1136}
1137
1138static int pvcalls_front_probe(struct xenbus_device *dev,
1139 const struct xenbus_device_id *id)
1140{
1141 int ret = -ENOMEM, evtchn, i;
1142 unsigned int max_page_order, function_calls, len;
1143 char *versions;
1144 grant_ref_t gref_head = 0;
1145 struct xenbus_transaction xbt;
1146 struct pvcalls_bedata *bedata = NULL;
1147 struct xen_pvcalls_sring *sring;
1148
1149 if (pvcalls_front_dev != NULL) {
1150 dev_err(&dev->dev, "only one PV Calls connection supported\n");
1151 return -EINVAL;
1152 }
1153
1154 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
1155 if (IS_ERR(versions))
1156 return PTR_ERR(versions);
1157 if (!len)
1158 return -EINVAL;
1159 if (strcmp(versions, "1")) {
1160 kfree(versions);
1161 return -EINVAL;
1162 }
1163 kfree(versions);
1164 max_page_order = xenbus_read_unsigned(dev->otherend,
1165 "max-page-order", 0);
1166 if (max_page_order < PVCALLS_RING_ORDER)
1167 return -ENODEV;
1168 function_calls = xenbus_read_unsigned(dev->otherend,
1169 "function-calls", 0);
1170 /* See XENBUS_FUNCTIONS_CALLS in pvcalls.h */
1171 if (function_calls != 1)
1172 return -ENODEV;
1173 pr_info("%s max-page-order is %u\n", __func__, max_page_order);
1174
1175 bedata = kzalloc(sizeof(struct pvcalls_bedata), GFP_KERNEL);
1176 if (!bedata)
1177 return -ENOMEM;
1178
1179 dev_set_drvdata(&dev->dev, bedata);
1180 pvcalls_front_dev = dev;
1181 init_waitqueue_head(&bedata->inflight_req);
1182 INIT_LIST_HEAD(&bedata->socket_mappings);
1183 spin_lock_init(&bedata->socket_lock);
1184 bedata->irq = -1;
1185 bedata->ref = -1;
1186
1187 for (i = 0; i < PVCALLS_NR_RSP_PER_RING; i++)
1188 bedata->rsp[i].req_id = PVCALLS_INVALID_ID;
1189
1190 sring = (struct xen_pvcalls_sring *) __get_free_page(GFP_KERNEL |
1191 __GFP_ZERO);
1192 if (!sring)
1193 goto error;
1194 SHARED_RING_INIT(sring);
1195 FRONT_RING_INIT(&bedata->ring, sring, XEN_PAGE_SIZE);
1196
1197 ret = xenbus_alloc_evtchn(dev, &evtchn);
1198 if (ret)
1199 goto error;
1200
1201 bedata->irq = bind_evtchn_to_irqhandler(evtchn,
1202 pvcalls_front_event_handler,
1203 0, "pvcalls-frontend", dev);
1204 if (bedata->irq < 0) {
1205 ret = bedata->irq;
1206 goto error;
1207 }
1208
1209 ret = gnttab_alloc_grant_references(1, &gref_head);
1210 if (ret < 0)
1211 goto error;
1212 ret = gnttab_claim_grant_reference(&gref_head);
1213 if (ret < 0)
1214 goto error;
1215 bedata->ref = ret;
1216 gnttab_grant_foreign_access_ref(bedata->ref, dev->otherend_id,
1217 virt_to_gfn((void *)sring), 0);
1218
1219 again:
1220 ret = xenbus_transaction_start(&xbt);
1221 if (ret) {
1222 xenbus_dev_fatal(dev, ret, "starting transaction");
1223 goto error;
1224 }
1225 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
1226 if (ret)
1227 goto error_xenbus;
1228 ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", bedata->ref);
1229 if (ret)
1230 goto error_xenbus;
1231 ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
1232 evtchn);
1233 if (ret)
1234 goto error_xenbus;
1235 ret = xenbus_transaction_end(xbt, 0);
1236 if (ret) {
1237 if (ret == -EAGAIN)
1238 goto again;
1239 xenbus_dev_fatal(dev, ret, "completing transaction");
1240 goto error;
1241 }
1242 xenbus_switch_state(dev, XenbusStateInitialised);
1243
1244 return 0;
1245
1246 error_xenbus:
1247 xenbus_transaction_end(xbt, 1);
1248 xenbus_dev_fatal(dev, ret, "writing xenstore");
1249 error:
1250 pvcalls_front_remove(dev);
1251 return ret;
1252}
1253
1254static void pvcalls_front_changed(struct xenbus_device *dev,
1255 enum xenbus_state backend_state)
1256{
1257 switch (backend_state) {
1258 case XenbusStateReconfiguring:
1259 case XenbusStateReconfigured:
1260 case XenbusStateInitialising:
1261 case XenbusStateInitialised:
1262 case XenbusStateUnknown:
1263 break;
1264
1265 case XenbusStateInitWait:
1266 break;
1267
1268 case XenbusStateConnected:
1269 xenbus_switch_state(dev, XenbusStateConnected);
1270 break;
1271
1272 case XenbusStateClosed:
1273 if (dev->state == XenbusStateClosed)
1274 break;
1275 /* Missed the backend's CLOSING state */
1276 /* fall through */
1277 case XenbusStateClosing:
1278 xenbus_frontend_closed(dev);
1279 break;
1280 }
1281}
1282
1283static struct xenbus_driver pvcalls_front_driver = {
1284 .ids = pvcalls_front_ids,
1285 .probe = pvcalls_front_probe,
1286 .remove = pvcalls_front_remove,
1287 .otherend_changed = pvcalls_front_changed,
1288};
1289
1290static int __init pvcalls_frontend_init(void)
1291{
1292 if (!xen_domain())
1293 return -ENODEV;
1294
1295 pr_info("Initialising Xen pvcalls frontend driver\n");
1296
1297 return xenbus_register_frontend(&pvcalls_front_driver);
1298}
1299
1300module_init(pvcalls_frontend_init);
1301
1302MODULE_DESCRIPTION("Xen PV Calls frontend driver");
1303MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>");
1304MODULE_LICENSE("GPL");
1305