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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
25static struct proto pvcalls_proto = {
26 .name = "PVCalls",
27 .owner = THIS_MODULE,
28 .obj_size = sizeof(struct sock),
29};
30
31struct 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. */
43static struct xenbus_device *pvcalls_front_dev;
44static 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
56struct 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
99static 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
116static 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
125static 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
134static 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
151static 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
165static 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
183again:
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
228static void free_active_ring(struct sock_mapping *map);
229
230static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
231 struct sock_mapping *map)
232{
233 int i;
234
235 unbind_from_irqhandler(map->active.irq, map);
236
237 spin_lock(&bedata->socket_lock);
238 if (!list_empty(&map->list))
239 list_del_init(&map->list);
240 spin_unlock(&bedata->socket_lock);
241
242 for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
243 gnttab_end_foreign_access(map->active.ring->ref[i], NULL);
244 gnttab_end_foreign_access(map->active.ref, NULL);
245 free_active_ring(map);
246
247 kfree(map);
248}
249
250static irqreturn_t pvcalls_front_conn_handler(int irq, void *sock_map)
251{
252 struct sock_mapping *map = sock_map;
253
254 if (map == NULL)
255 return IRQ_HANDLED;
256
257 wake_up_interruptible(&map->active.inflight_conn_req);
258
259 return IRQ_HANDLED;
260}
261
262int pvcalls_front_socket(struct socket *sock)
263{
264 struct pvcalls_bedata *bedata;
265 struct sock_mapping *map = NULL;
266 struct xen_pvcalls_request *req;
267 int notify, req_id, ret;
268
269 /*
270 * PVCalls only supports domain AF_INET,
271 * type SOCK_STREAM and protocol 0 sockets for now.
272 *
273 * Check socket type here, AF_INET and protocol checks are done
274 * by the caller.
275 */
276 if (sock->type != SOCK_STREAM)
277 return -EOPNOTSUPP;
278
279 pvcalls_enter();
280 if (!pvcalls_front_dev) {
281 pvcalls_exit();
282 return -EACCES;
283 }
284 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
285
286 map = kzalloc(sizeof(*map), GFP_KERNEL);
287 if (map == NULL) {
288 pvcalls_exit();
289 return -ENOMEM;
290 }
291
292 spin_lock(&bedata->socket_lock);
293
294 ret = get_request(bedata, &req_id);
295 if (ret < 0) {
296 kfree(map);
297 spin_unlock(&bedata->socket_lock);
298 pvcalls_exit();
299 return ret;
300 }
301
302 /*
303 * sock->sk->sk_send_head is not used for ip sockets: reuse the
304 * field to store a pointer to the struct sock_mapping
305 * corresponding to the socket. This way, we can easily get the
306 * struct sock_mapping from the struct socket.
307 */
308 sock->sk->sk_send_head = (void *)map;
309 list_add_tail(&map->list, &bedata->socket_mappings);
310
311 req = RING_GET_REQUEST(&bedata->ring, req_id);
312 req->req_id = req_id;
313 req->cmd = PVCALLS_SOCKET;
314 req->u.socket.id = (uintptr_t) map;
315 req->u.socket.domain = AF_INET;
316 req->u.socket.type = SOCK_STREAM;
317 req->u.socket.protocol = IPPROTO_IP;
318
319 bedata->ring.req_prod_pvt++;
320 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
321 spin_unlock(&bedata->socket_lock);
322 if (notify)
323 notify_remote_via_irq(bedata->irq);
324
325 wait_event(bedata->inflight_req,
326 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
327
328 /* read req_id, then the content */
329 smp_rmb();
330 ret = bedata->rsp[req_id].ret;
331 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
332
333 pvcalls_exit();
334 return ret;
335}
336
337static void free_active_ring(struct sock_mapping *map)
338{
339 if (!map->active.ring)
340 return;
341
342 free_pages_exact(map->active.data.in,
343 PAGE_SIZE << map->active.ring->ring_order);
344 free_page((unsigned long)map->active.ring);
345}
346
347static int alloc_active_ring(struct sock_mapping *map)
348{
349 void *bytes;
350
351 map->active.ring = (struct pvcalls_data_intf *)
352 get_zeroed_page(GFP_KERNEL);
353 if (!map->active.ring)
354 goto out;
355
356 map->active.ring->ring_order = PVCALLS_RING_ORDER;
357 bytes = alloc_pages_exact(PAGE_SIZE << PVCALLS_RING_ORDER,
358 GFP_KERNEL | __GFP_ZERO);
359 if (!bytes)
360 goto out;
361
362 map->active.data.in = bytes;
363 map->active.data.out = bytes +
364 XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
365
366 return 0;
367
368out:
369 free_active_ring(map);
370 return -ENOMEM;
371}
372
373static int create_active(struct sock_mapping *map, evtchn_port_t *evtchn)
374{
375 void *bytes;
376 int ret, irq = -1, i;
377
378 *evtchn = 0;
379 init_waitqueue_head(&map->active.inflight_conn_req);
380
381 bytes = map->active.data.in;
382 for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
383 map->active.ring->ref[i] = gnttab_grant_foreign_access(
384 pvcalls_front_dev->otherend_id,
385 pfn_to_gfn(virt_to_pfn(bytes) + i), 0);
386
387 map->active.ref = gnttab_grant_foreign_access(
388 pvcalls_front_dev->otherend_id,
389 pfn_to_gfn(virt_to_pfn((void *)map->active.ring)), 0);
390
391 ret = xenbus_alloc_evtchn(pvcalls_front_dev, evtchn);
392 if (ret)
393 goto out_error;
394 irq = bind_evtchn_to_irqhandler(*evtchn, pvcalls_front_conn_handler,
395 0, "pvcalls-frontend", map);
396 if (irq < 0) {
397 ret = irq;
398 goto out_error;
399 }
400
401 map->active.irq = irq;
402 map->active_socket = true;
403 mutex_init(&map->active.in_mutex);
404 mutex_init(&map->active.out_mutex);
405
406 return 0;
407
408out_error:
409 if (*evtchn > 0)
410 xenbus_free_evtchn(pvcalls_front_dev, *evtchn);
411 return ret;
412}
413
414int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
415 int addr_len, int flags)
416{
417 struct pvcalls_bedata *bedata;
418 struct sock_mapping *map = NULL;
419 struct xen_pvcalls_request *req;
420 int notify, req_id, ret;
421 evtchn_port_t evtchn;
422
423 if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
424 return -EOPNOTSUPP;
425
426 map = pvcalls_enter_sock(sock);
427 if (IS_ERR(map))
428 return PTR_ERR(map);
429
430 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
431 ret = alloc_active_ring(map);
432 if (ret < 0) {
433 pvcalls_exit_sock(sock);
434 return ret;
435 }
436
437 spin_lock(&bedata->socket_lock);
438 ret = get_request(bedata, &req_id);
439 if (ret < 0) {
440 spin_unlock(&bedata->socket_lock);
441 free_active_ring(map);
442 pvcalls_exit_sock(sock);
443 return ret;
444 }
445 ret = create_active(map, &evtchn);
446 if (ret < 0) {
447 spin_unlock(&bedata->socket_lock);
448 free_active_ring(map);
449 pvcalls_exit_sock(sock);
450 return ret;
451 }
452
453 req = RING_GET_REQUEST(&bedata->ring, req_id);
454 req->req_id = req_id;
455 req->cmd = PVCALLS_CONNECT;
456 req->u.connect.id = (uintptr_t)map;
457 req->u.connect.len = addr_len;
458 req->u.connect.flags = flags;
459 req->u.connect.ref = map->active.ref;
460 req->u.connect.evtchn = evtchn;
461 memcpy(req->u.connect.addr, addr, sizeof(*addr));
462
463 map->sock = sock;
464
465 bedata->ring.req_prod_pvt++;
466 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
467 spin_unlock(&bedata->socket_lock);
468
469 if (notify)
470 notify_remote_via_irq(bedata->irq);
471
472 wait_event(bedata->inflight_req,
473 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
474
475 /* read req_id, then the content */
476 smp_rmb();
477 ret = bedata->rsp[req_id].ret;
478 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
479 pvcalls_exit_sock(sock);
480 return ret;
481}
482
483static int __write_ring(struct pvcalls_data_intf *intf,
484 struct pvcalls_data *data,
485 struct iov_iter *msg_iter,
486 int len)
487{
488 RING_IDX cons, prod, size, masked_prod, masked_cons;
489 RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
490 int32_t error;
491
492 error = intf->out_error;
493 if (error < 0)
494 return error;
495 cons = intf->out_cons;
496 prod = intf->out_prod;
497 /* read indexes before continuing */
498 virt_mb();
499
500 size = pvcalls_queued(prod, cons, array_size);
501 if (size > array_size)
502 return -EINVAL;
503 if (size == array_size)
504 return 0;
505 if (len > array_size - size)
506 len = array_size - size;
507
508 masked_prod = pvcalls_mask(prod, array_size);
509 masked_cons = pvcalls_mask(cons, array_size);
510
511 if (masked_prod < masked_cons) {
512 len = copy_from_iter(data->out + masked_prod, len, msg_iter);
513 } else {
514 if (len > array_size - masked_prod) {
515 int ret = copy_from_iter(data->out + masked_prod,
516 array_size - masked_prod, msg_iter);
517 if (ret != array_size - masked_prod) {
518 len = ret;
519 goto out;
520 }
521 len = ret + copy_from_iter(data->out, len - ret, msg_iter);
522 } else {
523 len = copy_from_iter(data->out + masked_prod, len, msg_iter);
524 }
525 }
526out:
527 /* write to ring before updating pointer */
528 virt_wmb();
529 intf->out_prod += len;
530
531 return len;
532}
533
534int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg,
535 size_t len)
536{
537 struct sock_mapping *map;
538 int sent, tot_sent = 0;
539 int count = 0, flags;
540
541 flags = msg->msg_flags;
542 if (flags & (MSG_CONFIRM|MSG_DONTROUTE|MSG_EOR|MSG_OOB))
543 return -EOPNOTSUPP;
544
545 map = pvcalls_enter_sock(sock);
546 if (IS_ERR(map))
547 return PTR_ERR(map);
548
549 mutex_lock(&map->active.out_mutex);
550 if ((flags & MSG_DONTWAIT) && !pvcalls_front_write_todo(map)) {
551 mutex_unlock(&map->active.out_mutex);
552 pvcalls_exit_sock(sock);
553 return -EAGAIN;
554 }
555 if (len > INT_MAX)
556 len = INT_MAX;
557
558again:
559 count++;
560 sent = __write_ring(map->active.ring,
561 &map->active.data, &msg->msg_iter,
562 len);
563 if (sent > 0) {
564 len -= sent;
565 tot_sent += sent;
566 notify_remote_via_irq(map->active.irq);
567 }
568 if (sent >= 0 && len > 0 && count < PVCALLS_FRONT_MAX_SPIN)
569 goto again;
570 if (sent < 0)
571 tot_sent = sent;
572
573 mutex_unlock(&map->active.out_mutex);
574 pvcalls_exit_sock(sock);
575 return tot_sent;
576}
577
578static int __read_ring(struct pvcalls_data_intf *intf,
579 struct pvcalls_data *data,
580 struct iov_iter *msg_iter,
581 size_t len, int flags)
582{
583 RING_IDX cons, prod, size, masked_prod, masked_cons;
584 RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
585 int32_t error;
586
587 cons = intf->in_cons;
588 prod = intf->in_prod;
589 error = intf->in_error;
590 /* get pointers before reading from the ring */
591 virt_rmb();
592
593 size = pvcalls_queued(prod, cons, array_size);
594 masked_prod = pvcalls_mask(prod, array_size);
595 masked_cons = pvcalls_mask(cons, array_size);
596
597 if (size == 0)
598 return error ?: size;
599
600 if (len > size)
601 len = size;
602
603 if (masked_prod > masked_cons) {
604 len = copy_to_iter(data->in + masked_cons, len, msg_iter);
605 } else {
606 if (len > (array_size - masked_cons)) {
607 int ret = copy_to_iter(data->in + masked_cons,
608 array_size - masked_cons, msg_iter);
609 if (ret != array_size - masked_cons) {
610 len = ret;
611 goto out;
612 }
613 len = ret + copy_to_iter(data->in, len - ret, msg_iter);
614 } else {
615 len = copy_to_iter(data->in + masked_cons, len, msg_iter);
616 }
617 }
618out:
619 /* read data from the ring before increasing the index */
620 virt_mb();
621 if (!(flags & MSG_PEEK))
622 intf->in_cons += len;
623
624 return len;
625}
626
627int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
628 int flags)
629{
630 int ret;
631 struct sock_mapping *map;
632
633 if (flags & (MSG_CMSG_CLOEXEC|MSG_ERRQUEUE|MSG_OOB|MSG_TRUNC))
634 return -EOPNOTSUPP;
635
636 map = pvcalls_enter_sock(sock);
637 if (IS_ERR(map))
638 return PTR_ERR(map);
639
640 mutex_lock(&map->active.in_mutex);
641 if (len > XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER))
642 len = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
643
644 while (!(flags & MSG_DONTWAIT) && !pvcalls_front_read_todo(map)) {
645 wait_event_interruptible(map->active.inflight_conn_req,
646 pvcalls_front_read_todo(map));
647 }
648 ret = __read_ring(map->active.ring, &map->active.data,
649 &msg->msg_iter, len, flags);
650
651 if (ret > 0)
652 notify_remote_via_irq(map->active.irq);
653 if (ret == 0)
654 ret = (flags & MSG_DONTWAIT) ? -EAGAIN : 0;
655 if (ret == -ENOTCONN)
656 ret = 0;
657
658 mutex_unlock(&map->active.in_mutex);
659 pvcalls_exit_sock(sock);
660 return ret;
661}
662
663int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
664{
665 struct pvcalls_bedata *bedata;
666 struct sock_mapping *map = NULL;
667 struct xen_pvcalls_request *req;
668 int notify, req_id, ret;
669
670 if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
671 return -EOPNOTSUPP;
672
673 map = pvcalls_enter_sock(sock);
674 if (IS_ERR(map))
675 return PTR_ERR(map);
676 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
677
678 spin_lock(&bedata->socket_lock);
679 ret = get_request(bedata, &req_id);
680 if (ret < 0) {
681 spin_unlock(&bedata->socket_lock);
682 pvcalls_exit_sock(sock);
683 return ret;
684 }
685 req = RING_GET_REQUEST(&bedata->ring, req_id);
686 req->req_id = req_id;
687 map->sock = sock;
688 req->cmd = PVCALLS_BIND;
689 req->u.bind.id = (uintptr_t)map;
690 memcpy(req->u.bind.addr, addr, sizeof(*addr));
691 req->u.bind.len = addr_len;
692
693 init_waitqueue_head(&map->passive.inflight_accept_req);
694
695 map->active_socket = false;
696
697 bedata->ring.req_prod_pvt++;
698 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
699 spin_unlock(&bedata->socket_lock);
700 if (notify)
701 notify_remote_via_irq(bedata->irq);
702
703 wait_event(bedata->inflight_req,
704 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
705
706 /* read req_id, then the content */
707 smp_rmb();
708 ret = bedata->rsp[req_id].ret;
709 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
710
711 map->passive.status = PVCALLS_STATUS_BIND;
712 pvcalls_exit_sock(sock);
713 return 0;
714}
715
716int pvcalls_front_listen(struct socket *sock, int backlog)
717{
718 struct pvcalls_bedata *bedata;
719 struct sock_mapping *map;
720 struct xen_pvcalls_request *req;
721 int notify, req_id, ret;
722
723 map = pvcalls_enter_sock(sock);
724 if (IS_ERR(map))
725 return PTR_ERR(map);
726 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
727
728 if (map->passive.status != PVCALLS_STATUS_BIND) {
729 pvcalls_exit_sock(sock);
730 return -EOPNOTSUPP;
731 }
732
733 spin_lock(&bedata->socket_lock);
734 ret = get_request(bedata, &req_id);
735 if (ret < 0) {
736 spin_unlock(&bedata->socket_lock);
737 pvcalls_exit_sock(sock);
738 return ret;
739 }
740 req = RING_GET_REQUEST(&bedata->ring, req_id);
741 req->req_id = req_id;
742 req->cmd = PVCALLS_LISTEN;
743 req->u.listen.id = (uintptr_t) map;
744 req->u.listen.backlog = backlog;
745
746 bedata->ring.req_prod_pvt++;
747 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
748 spin_unlock(&bedata->socket_lock);
749 if (notify)
750 notify_remote_via_irq(bedata->irq);
751
752 wait_event(bedata->inflight_req,
753 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
754
755 /* read req_id, then the content */
756 smp_rmb();
757 ret = bedata->rsp[req_id].ret;
758 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
759
760 map->passive.status = PVCALLS_STATUS_LISTEN;
761 pvcalls_exit_sock(sock);
762 return ret;
763}
764
765int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
766{
767 struct pvcalls_bedata *bedata;
768 struct sock_mapping *map;
769 struct sock_mapping *map2 = NULL;
770 struct xen_pvcalls_request *req;
771 int notify, req_id, ret, nonblock;
772 evtchn_port_t evtchn;
773
774 map = pvcalls_enter_sock(sock);
775 if (IS_ERR(map))
776 return PTR_ERR(map);
777 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
778
779 if (map->passive.status != PVCALLS_STATUS_LISTEN) {
780 pvcalls_exit_sock(sock);
781 return -EINVAL;
782 }
783
784 nonblock = flags & SOCK_NONBLOCK;
785 /*
786 * Backend only supports 1 inflight accept request, will return
787 * errors for the others
788 */
789 if (test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
790 (void *)&map->passive.flags)) {
791 req_id = READ_ONCE(map->passive.inflight_req_id);
792 if (req_id != PVCALLS_INVALID_ID &&
793 READ_ONCE(bedata->rsp[req_id].req_id) == req_id) {
794 map2 = map->passive.accept_map;
795 goto received;
796 }
797 if (nonblock) {
798 pvcalls_exit_sock(sock);
799 return -EAGAIN;
800 }
801 if (wait_event_interruptible(map->passive.inflight_accept_req,
802 !test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
803 (void *)&map->passive.flags))) {
804 pvcalls_exit_sock(sock);
805 return -EINTR;
806 }
807 }
808
809 map2 = kzalloc(sizeof(*map2), GFP_KERNEL);
810 if (map2 == NULL) {
811 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
812 (void *)&map->passive.flags);
813 pvcalls_exit_sock(sock);
814 return -ENOMEM;
815 }
816 ret = alloc_active_ring(map2);
817 if (ret < 0) {
818 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
819 (void *)&map->passive.flags);
820 kfree(map2);
821 pvcalls_exit_sock(sock);
822 return ret;
823 }
824 spin_lock(&bedata->socket_lock);
825 ret = get_request(bedata, &req_id);
826 if (ret < 0) {
827 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
828 (void *)&map->passive.flags);
829 spin_unlock(&bedata->socket_lock);
830 free_active_ring(map2);
831 kfree(map2);
832 pvcalls_exit_sock(sock);
833 return ret;
834 }
835
836 ret = create_active(map2, &evtchn);
837 if (ret < 0) {
838 free_active_ring(map2);
839 kfree(map2);
840 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
841 (void *)&map->passive.flags);
842 spin_unlock(&bedata->socket_lock);
843 pvcalls_exit_sock(sock);
844 return ret;
845 }
846 list_add_tail(&map2->list, &bedata->socket_mappings);
847
848 req = RING_GET_REQUEST(&bedata->ring, req_id);
849 req->req_id = req_id;
850 req->cmd = PVCALLS_ACCEPT;
851 req->u.accept.id = (uintptr_t) map;
852 req->u.accept.ref = map2->active.ref;
853 req->u.accept.id_new = (uintptr_t) map2;
854 req->u.accept.evtchn = evtchn;
855 map->passive.accept_map = map2;
856
857 bedata->ring.req_prod_pvt++;
858 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
859 spin_unlock(&bedata->socket_lock);
860 if (notify)
861 notify_remote_via_irq(bedata->irq);
862 /* We could check if we have received a response before returning. */
863 if (nonblock) {
864 WRITE_ONCE(map->passive.inflight_req_id, req_id);
865 pvcalls_exit_sock(sock);
866 return -EAGAIN;
867 }
868
869 if (wait_event_interruptible(bedata->inflight_req,
870 READ_ONCE(bedata->rsp[req_id].req_id) == req_id)) {
871 pvcalls_exit_sock(sock);
872 return -EINTR;
873 }
874 /* read req_id, then the content */
875 smp_rmb();
876
877received:
878 map2->sock = newsock;
879 newsock->sk = sk_alloc(sock_net(sock->sk), PF_INET, GFP_KERNEL, &pvcalls_proto, false);
880 if (!newsock->sk) {
881 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
882 map->passive.inflight_req_id = PVCALLS_INVALID_ID;
883 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
884 (void *)&map->passive.flags);
885 pvcalls_front_free_map(bedata, map2);
886 pvcalls_exit_sock(sock);
887 return -ENOMEM;
888 }
889 newsock->sk->sk_send_head = (void *)map2;
890
891 ret = bedata->rsp[req_id].ret;
892 bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
893 map->passive.inflight_req_id = PVCALLS_INVALID_ID;
894
895 clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags);
896 wake_up(&map->passive.inflight_accept_req);
897
898 pvcalls_exit_sock(sock);
899 return ret;
900}
901
902static __poll_t pvcalls_front_poll_passive(struct file *file,
903 struct pvcalls_bedata *bedata,
904 struct sock_mapping *map,
905 poll_table *wait)
906{
907 int notify, req_id, ret;
908 struct xen_pvcalls_request *req;
909
910 if (test_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
911 (void *)&map->passive.flags)) {
912 uint32_t req_id = READ_ONCE(map->passive.inflight_req_id);
913
914 if (req_id != PVCALLS_INVALID_ID &&
915 READ_ONCE(bedata->rsp[req_id].req_id) == req_id)
916 return EPOLLIN | EPOLLRDNORM;
917
918 poll_wait(file, &map->passive.inflight_accept_req, wait);
919 return 0;
920 }
921
922 if (test_and_clear_bit(PVCALLS_FLAG_POLL_RET,
923 (void *)&map->passive.flags))
924 return EPOLLIN | EPOLLRDNORM;
925
926 /*
927 * First check RET, then INFLIGHT. No barriers necessary to
928 * ensure execution ordering because of the conditional
929 * instructions creating control dependencies.
930 */
931
932 if (test_and_set_bit(PVCALLS_FLAG_POLL_INFLIGHT,
933 (void *)&map->passive.flags)) {
934 poll_wait(file, &bedata->inflight_req, wait);
935 return 0;
936 }
937
938 spin_lock(&bedata->socket_lock);
939 ret = get_request(bedata, &req_id);
940 if (ret < 0) {
941 spin_unlock(&bedata->socket_lock);
942 return ret;
943 }
944 req = RING_GET_REQUEST(&bedata->ring, req_id);
945 req->req_id = req_id;
946 req->cmd = PVCALLS_POLL;
947 req->u.poll.id = (uintptr_t) map;
948
949 bedata->ring.req_prod_pvt++;
950 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
951 spin_unlock(&bedata->socket_lock);
952 if (notify)
953 notify_remote_via_irq(bedata->irq);
954
955 poll_wait(file, &bedata->inflight_req, wait);
956 return 0;
957}
958
959static __poll_t pvcalls_front_poll_active(struct file *file,
960 struct pvcalls_bedata *bedata,
961 struct sock_mapping *map,
962 poll_table *wait)
963{
964 __poll_t mask = 0;
965 int32_t in_error, out_error;
966 struct pvcalls_data_intf *intf = map->active.ring;
967
968 out_error = intf->out_error;
969 in_error = intf->in_error;
970
971 poll_wait(file, &map->active.inflight_conn_req, wait);
972 if (pvcalls_front_write_todo(map))
973 mask |= EPOLLOUT | EPOLLWRNORM;
974 if (pvcalls_front_read_todo(map))
975 mask |= EPOLLIN | EPOLLRDNORM;
976 if (in_error != 0 || out_error != 0)
977 mask |= EPOLLERR;
978
979 return mask;
980}
981
982__poll_t pvcalls_front_poll(struct file *file, struct socket *sock,
983 poll_table *wait)
984{
985 struct pvcalls_bedata *bedata;
986 struct sock_mapping *map;
987 __poll_t ret;
988
989 map = pvcalls_enter_sock(sock);
990 if (IS_ERR(map))
991 return EPOLLNVAL;
992 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
993
994 if (map->active_socket)
995 ret = pvcalls_front_poll_active(file, bedata, map, wait);
996 else
997 ret = pvcalls_front_poll_passive(file, bedata, map, wait);
998 pvcalls_exit_sock(sock);
999 return ret;
1000}
1001
1002int pvcalls_front_release(struct socket *sock)
1003{
1004 struct pvcalls_bedata *bedata;
1005 struct sock_mapping *map;
1006 int req_id, notify, ret;
1007 struct xen_pvcalls_request *req;
1008
1009 if (sock->sk == NULL)
1010 return 0;
1011
1012 map = pvcalls_enter_sock(sock);
1013 if (IS_ERR(map)) {
1014 if (PTR_ERR(map) == -ENOTCONN)
1015 return -EIO;
1016 else
1017 return 0;
1018 }
1019 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
1020
1021 spin_lock(&bedata->socket_lock);
1022 ret = get_request(bedata, &req_id);
1023 if (ret < 0) {
1024 spin_unlock(&bedata->socket_lock);
1025 pvcalls_exit_sock(sock);
1026 return ret;
1027 }
1028 sock->sk->sk_send_head = NULL;
1029
1030 req = RING_GET_REQUEST(&bedata->ring, req_id);
1031 req->req_id = req_id;
1032 req->cmd = PVCALLS_RELEASE;
1033 req->u.release.id = (uintptr_t)map;
1034
1035 bedata->ring.req_prod_pvt++;
1036 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
1037 spin_unlock(&bedata->socket_lock);
1038 if (notify)
1039 notify_remote_via_irq(bedata->irq);
1040
1041 wait_event(bedata->inflight_req,
1042 READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
1043
1044 if (map->active_socket) {
1045 /*
1046 * Set in_error and wake up inflight_conn_req to force
1047 * recvmsg waiters to exit.
1048 */
1049 map->active.ring->in_error = -EBADF;
1050 wake_up_interruptible(&map->active.inflight_conn_req);
1051
1052 /*
1053 * We need to make sure that sendmsg/recvmsg on this socket have
1054 * not started before we've cleared sk_send_head here. The
1055 * easiest way to guarantee this is to see that no pvcalls
1056 * (other than us) is in progress on this socket.
1057 */
1058 while (atomic_read(&map->refcount) > 1)
1059 cpu_relax();
1060
1061 pvcalls_front_free_map(bedata, map);
1062 } else {
1063 wake_up(&bedata->inflight_req);
1064 wake_up(&map->passive.inflight_accept_req);
1065
1066 while (atomic_read(&map->refcount) > 1)
1067 cpu_relax();
1068
1069 spin_lock(&bedata->socket_lock);
1070 list_del(&map->list);
1071 spin_unlock(&bedata->socket_lock);
1072 if (READ_ONCE(map->passive.inflight_req_id) != PVCALLS_INVALID_ID &&
1073 READ_ONCE(map->passive.inflight_req_id) != 0) {
1074 pvcalls_front_free_map(bedata,
1075 map->passive.accept_map);
1076 }
1077 kfree(map);
1078 }
1079 WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID);
1080
1081 pvcalls_exit();
1082 return 0;
1083}
1084
1085static const struct xenbus_device_id pvcalls_front_ids[] = {
1086 { "pvcalls" },
1087 { "" }
1088};
1089
1090static void pvcalls_front_remove(struct xenbus_device *dev)
1091{
1092 struct pvcalls_bedata *bedata;
1093 struct sock_mapping *map = NULL, *n;
1094
1095 bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
1096 dev_set_drvdata(&dev->dev, NULL);
1097 pvcalls_front_dev = NULL;
1098 if (bedata->irq >= 0)
1099 unbind_from_irqhandler(bedata->irq, dev);
1100
1101 list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
1102 map->sock->sk->sk_send_head = NULL;
1103 if (map->active_socket) {
1104 map->active.ring->in_error = -EBADF;
1105 wake_up_interruptible(&map->active.inflight_conn_req);
1106 }
1107 }
1108
1109 smp_mb();
1110 while (atomic_read(&pvcalls_refcount) > 0)
1111 cpu_relax();
1112 list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
1113 if (map->active_socket) {
1114 /* No need to lock, refcount is 0 */
1115 pvcalls_front_free_map(bedata, map);
1116 } else {
1117 list_del(&map->list);
1118 kfree(map);
1119 }
1120 }
1121 if (bedata->ref != -1)
1122 gnttab_end_foreign_access(bedata->ref, NULL);
1123 kfree(bedata->ring.sring);
1124 kfree(bedata);
1125 xenbus_switch_state(dev, XenbusStateClosed);
1126}
1127
1128static int pvcalls_front_probe(struct xenbus_device *dev,
1129 const struct xenbus_device_id *id)
1130{
1131 int ret = -ENOMEM, i;
1132 evtchn_port_t evtchn;
1133 unsigned int max_page_order, function_calls, len;
1134 char *versions;
1135 grant_ref_t gref_head = 0;
1136 struct xenbus_transaction xbt;
1137 struct pvcalls_bedata *bedata = NULL;
1138 struct xen_pvcalls_sring *sring;
1139
1140 if (pvcalls_front_dev != NULL) {
1141 dev_err(&dev->dev, "only one PV Calls connection supported\n");
1142 return -EINVAL;
1143 }
1144
1145 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
1146 if (IS_ERR(versions))
1147 return PTR_ERR(versions);
1148 if (!len)
1149 return -EINVAL;
1150 if (strcmp(versions, "1")) {
1151 kfree(versions);
1152 return -EINVAL;
1153 }
1154 kfree(versions);
1155 max_page_order = xenbus_read_unsigned(dev->otherend,
1156 "max-page-order", 0);
1157 if (max_page_order < PVCALLS_RING_ORDER)
1158 return -ENODEV;
1159 function_calls = xenbus_read_unsigned(dev->otherend,
1160 "function-calls", 0);
1161 /* See XENBUS_FUNCTIONS_CALLS in pvcalls.h */
1162 if (function_calls != 1)
1163 return -ENODEV;
1164 pr_info("%s max-page-order is %u\n", __func__, max_page_order);
1165
1166 bedata = kzalloc(sizeof(struct pvcalls_bedata), GFP_KERNEL);
1167 if (!bedata)
1168 return -ENOMEM;
1169
1170 dev_set_drvdata(&dev->dev, bedata);
1171 pvcalls_front_dev = dev;
1172 init_waitqueue_head(&bedata->inflight_req);
1173 INIT_LIST_HEAD(&bedata->socket_mappings);
1174 spin_lock_init(&bedata->socket_lock);
1175 bedata->irq = -1;
1176 bedata->ref = -1;
1177
1178 for (i = 0; i < PVCALLS_NR_RSP_PER_RING; i++)
1179 bedata->rsp[i].req_id = PVCALLS_INVALID_ID;
1180
1181 sring = (struct xen_pvcalls_sring *) __get_free_page(GFP_KERNEL |
1182 __GFP_ZERO);
1183 if (!sring)
1184 goto error;
1185 SHARED_RING_INIT(sring);
1186 FRONT_RING_INIT(&bedata->ring, sring, XEN_PAGE_SIZE);
1187
1188 ret = xenbus_alloc_evtchn(dev, &evtchn);
1189 if (ret)
1190 goto error;
1191
1192 bedata->irq = bind_evtchn_to_irqhandler(evtchn,
1193 pvcalls_front_event_handler,
1194 0, "pvcalls-frontend", dev);
1195 if (bedata->irq < 0) {
1196 ret = bedata->irq;
1197 goto error;
1198 }
1199
1200 ret = gnttab_alloc_grant_references(1, &gref_head);
1201 if (ret < 0)
1202 goto error;
1203 ret = gnttab_claim_grant_reference(&gref_head);
1204 if (ret < 0)
1205 goto error;
1206 bedata->ref = ret;
1207 gnttab_grant_foreign_access_ref(bedata->ref, dev->otherend_id,
1208 virt_to_gfn((void *)sring), 0);
1209
1210 again:
1211 ret = xenbus_transaction_start(&xbt);
1212 if (ret) {
1213 xenbus_dev_fatal(dev, ret, "starting transaction");
1214 goto error;
1215 }
1216 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
1217 if (ret)
1218 goto error_xenbus;
1219 ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", bedata->ref);
1220 if (ret)
1221 goto error_xenbus;
1222 ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
1223 evtchn);
1224 if (ret)
1225 goto error_xenbus;
1226 ret = xenbus_transaction_end(xbt, 0);
1227 if (ret) {
1228 if (ret == -EAGAIN)
1229 goto again;
1230 xenbus_dev_fatal(dev, ret, "completing transaction");
1231 goto error;
1232 }
1233 xenbus_switch_state(dev, XenbusStateInitialised);
1234
1235 return 0;
1236
1237 error_xenbus:
1238 xenbus_transaction_end(xbt, 1);
1239 xenbus_dev_fatal(dev, ret, "writing xenstore");
1240 error:
1241 pvcalls_front_remove(dev);
1242 return ret;
1243}
1244
1245static void pvcalls_front_changed(struct xenbus_device *dev,
1246 enum xenbus_state backend_state)
1247{
1248 switch (backend_state) {
1249 case XenbusStateReconfiguring:
1250 case XenbusStateReconfigured:
1251 case XenbusStateInitialising:
1252 case XenbusStateInitialised:
1253 case XenbusStateUnknown:
1254 break;
1255
1256 case XenbusStateInitWait:
1257 break;
1258
1259 case XenbusStateConnected:
1260 xenbus_switch_state(dev, XenbusStateConnected);
1261 break;
1262
1263 case XenbusStateClosed:
1264 if (dev->state == XenbusStateClosed)
1265 break;
1266 /* Missed the backend's CLOSING state */
1267 fallthrough;
1268 case XenbusStateClosing:
1269 xenbus_frontend_closed(dev);
1270 break;
1271 }
1272}
1273
1274static struct xenbus_driver pvcalls_front_driver = {
1275 .ids = pvcalls_front_ids,
1276 .probe = pvcalls_front_probe,
1277 .remove = pvcalls_front_remove,
1278 .otherend_changed = pvcalls_front_changed,
1279 .not_essential = true,
1280};
1281
1282static int __init pvcalls_frontend_init(void)
1283{
1284 if (!xen_domain())
1285 return -ENODEV;
1286
1287 pr_info("Initialising Xen pvcalls frontend driver\n");
1288
1289 return xenbus_register_frontend(&pvcalls_front_driver);
1290}
1291
1292module_init(pvcalls_frontend_init);
1293
1294MODULE_DESCRIPTION("Xen PV Calls frontend driver");
1295MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>");
1296MODULE_LICENSE("GPL");