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