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1 | /* |
2 | * AF_XDP network backend. | |
3 | * | |
4 | * Copyright (c) 2023 Red Hat, Inc. | |
5 | * | |
6 | * Authors: | |
7 | * Ilya Maximets <i.maximets@ovn.org> | |
8 | * | |
9 | * This work is licensed under the terms of the GNU GPL, version 2 or later. | |
10 | * See the COPYING file in the top-level directory. | |
11 | */ | |
12 | ||
13 | ||
14 | #include "qemu/osdep.h" | |
15 | #include <bpf/bpf.h> | |
16 | #include <inttypes.h> | |
17 | #include <linux/if_link.h> | |
18 | #include <linux/if_xdp.h> | |
19 | #include <net/if.h> | |
20 | #include <xdp/xsk.h> | |
21 | ||
22 | #include "clients.h" | |
23 | #include "monitor/monitor.h" | |
24 | #include "net/net.h" | |
25 | #include "qapi/error.h" | |
26 | #include "qemu/cutils.h" | |
27 | #include "qemu/error-report.h" | |
28 | #include "qemu/iov.h" | |
29 | #include "qemu/main-loop.h" | |
30 | #include "qemu/memalign.h" | |
31 | ||
32 | ||
33 | typedef struct AFXDPState { | |
34 | NetClientState nc; | |
35 | ||
36 | struct xsk_socket *xsk; | |
37 | struct xsk_ring_cons rx; | |
38 | struct xsk_ring_prod tx; | |
39 | struct xsk_ring_cons cq; | |
40 | struct xsk_ring_prod fq; | |
41 | ||
42 | char ifname[IFNAMSIZ]; | |
43 | int ifindex; | |
44 | bool read_poll; | |
45 | bool write_poll; | |
46 | uint32_t outstanding_tx; | |
47 | ||
48 | uint64_t *pool; | |
49 | uint32_t n_pool; | |
50 | char *buffer; | |
51 | struct xsk_umem *umem; | |
52 | ||
53 | uint32_t n_queues; | |
54 | uint32_t xdp_flags; | |
55 | bool inhibit; | |
56 | } AFXDPState; | |
57 | ||
58 | #define AF_XDP_BATCH_SIZE 64 | |
59 | ||
60 | static void af_xdp_send(void *opaque); | |
61 | static void af_xdp_writable(void *opaque); | |
62 | ||
63 | /* Set the event-loop handlers for the af-xdp backend. */ | |
64 | static void af_xdp_update_fd_handler(AFXDPState *s) | |
65 | { | |
66 | qemu_set_fd_handler(xsk_socket__fd(s->xsk), | |
67 | s->read_poll ? af_xdp_send : NULL, | |
68 | s->write_poll ? af_xdp_writable : NULL, | |
69 | s); | |
70 | } | |
71 | ||
72 | /* Update the read handler. */ | |
73 | static void af_xdp_read_poll(AFXDPState *s, bool enable) | |
74 | { | |
75 | if (s->read_poll != enable) { | |
76 | s->read_poll = enable; | |
77 | af_xdp_update_fd_handler(s); | |
78 | } | |
79 | } | |
80 | ||
81 | /* Update the write handler. */ | |
82 | static void af_xdp_write_poll(AFXDPState *s, bool enable) | |
83 | { | |
84 | if (s->write_poll != enable) { | |
85 | s->write_poll = enable; | |
86 | af_xdp_update_fd_handler(s); | |
87 | } | |
88 | } | |
89 | ||
90 | static void af_xdp_poll(NetClientState *nc, bool enable) | |
91 | { | |
92 | AFXDPState *s = DO_UPCAST(AFXDPState, nc, nc); | |
93 | ||
94 | if (s->read_poll != enable || s->write_poll != enable) { | |
95 | s->write_poll = enable; | |
96 | s->read_poll = enable; | |
97 | af_xdp_update_fd_handler(s); | |
98 | } | |
99 | } | |
100 | ||
101 | static void af_xdp_complete_tx(AFXDPState *s) | |
102 | { | |
103 | uint32_t idx = 0; | |
104 | uint32_t done, i; | |
105 | uint64_t *addr; | |
106 | ||
107 | done = xsk_ring_cons__peek(&s->cq, XSK_RING_CONS__DEFAULT_NUM_DESCS, &idx); | |
108 | ||
109 | for (i = 0; i < done; i++) { | |
110 | addr = (void *) xsk_ring_cons__comp_addr(&s->cq, idx++); | |
111 | s->pool[s->n_pool++] = *addr; | |
112 | s->outstanding_tx--; | |
113 | } | |
114 | ||
115 | if (done) { | |
116 | xsk_ring_cons__release(&s->cq, done); | |
117 | } | |
118 | } | |
119 | ||
120 | /* | |
121 | * The fd_write() callback, invoked if the fd is marked as writable | |
122 | * after a poll. | |
123 | */ | |
124 | static void af_xdp_writable(void *opaque) | |
125 | { | |
126 | AFXDPState *s = opaque; | |
127 | ||
128 | /* Try to recover buffers that are already sent. */ | |
129 | af_xdp_complete_tx(s); | |
130 | ||
131 | /* | |
132 | * Unregister the handler, unless we still have packets to transmit | |
133 | * and kernel needs a wake up. | |
134 | */ | |
135 | if (!s->outstanding_tx || !xsk_ring_prod__needs_wakeup(&s->tx)) { | |
136 | af_xdp_write_poll(s, false); | |
137 | } | |
138 | ||
139 | /* Flush any buffered packets. */ | |
140 | qemu_flush_queued_packets(&s->nc); | |
141 | } | |
142 | ||
143 | static ssize_t af_xdp_receive(NetClientState *nc, | |
144 | const uint8_t *buf, size_t size) | |
145 | { | |
146 | AFXDPState *s = DO_UPCAST(AFXDPState, nc, nc); | |
147 | struct xdp_desc *desc; | |
148 | uint32_t idx; | |
149 | void *data; | |
150 | ||
151 | /* Try to recover buffers that are already sent. */ | |
152 | af_xdp_complete_tx(s); | |
153 | ||
154 | if (size > XSK_UMEM__DEFAULT_FRAME_SIZE) { | |
155 | /* We can't transmit packet this size... */ | |
156 | return size; | |
157 | } | |
158 | ||
159 | if (!s->n_pool || !xsk_ring_prod__reserve(&s->tx, 1, &idx)) { | |
160 | /* | |
161 | * Out of buffers or space in tx ring. Poll until we can write. | |
162 | * This will also kick the Tx, if it was waiting on CQ. | |
163 | */ | |
164 | af_xdp_write_poll(s, true); | |
165 | return 0; | |
166 | } | |
167 | ||
168 | desc = xsk_ring_prod__tx_desc(&s->tx, idx); | |
169 | desc->addr = s->pool[--s->n_pool]; | |
170 | desc->len = size; | |
171 | ||
172 | data = xsk_umem__get_data(s->buffer, desc->addr); | |
173 | memcpy(data, buf, size); | |
174 | ||
175 | xsk_ring_prod__submit(&s->tx, 1); | |
176 | s->outstanding_tx++; | |
177 | ||
178 | if (xsk_ring_prod__needs_wakeup(&s->tx)) { | |
179 | af_xdp_write_poll(s, true); | |
180 | } | |
181 | ||
182 | return size; | |
183 | } | |
184 | ||
185 | /* | |
186 | * Complete a previous send (backend --> guest) and enable the | |
187 | * fd_read callback. | |
188 | */ | |
189 | static void af_xdp_send_completed(NetClientState *nc, ssize_t len) | |
190 | { | |
191 | AFXDPState *s = DO_UPCAST(AFXDPState, nc, nc); | |
192 | ||
193 | af_xdp_read_poll(s, true); | |
194 | } | |
195 | ||
196 | static void af_xdp_fq_refill(AFXDPState *s, uint32_t n) | |
197 | { | |
198 | uint32_t i, idx = 0; | |
199 | ||
200 | /* Leave one packet for Tx, just in case. */ | |
201 | if (s->n_pool < n + 1) { | |
202 | n = s->n_pool; | |
203 | } | |
204 | ||
205 | if (!n || !xsk_ring_prod__reserve(&s->fq, n, &idx)) { | |
206 | return; | |
207 | } | |
208 | ||
209 | for (i = 0; i < n; i++) { | |
210 | *xsk_ring_prod__fill_addr(&s->fq, idx++) = s->pool[--s->n_pool]; | |
211 | } | |
212 | xsk_ring_prod__submit(&s->fq, n); | |
213 | ||
214 | if (xsk_ring_prod__needs_wakeup(&s->fq)) { | |
215 | /* Receive was blocked by not having enough buffers. Wake it up. */ | |
216 | af_xdp_read_poll(s, true); | |
217 | } | |
218 | } | |
219 | ||
220 | static void af_xdp_send(void *opaque) | |
221 | { | |
222 | uint32_t i, n_rx, idx = 0; | |
223 | AFXDPState *s = opaque; | |
224 | ||
225 | n_rx = xsk_ring_cons__peek(&s->rx, AF_XDP_BATCH_SIZE, &idx); | |
226 | if (!n_rx) { | |
227 | return; | |
228 | } | |
229 | ||
230 | for (i = 0; i < n_rx; i++) { | |
231 | const struct xdp_desc *desc; | |
232 | struct iovec iov; | |
233 | ||
234 | desc = xsk_ring_cons__rx_desc(&s->rx, idx++); | |
235 | ||
236 | iov.iov_base = xsk_umem__get_data(s->buffer, desc->addr); | |
237 | iov.iov_len = desc->len; | |
238 | ||
239 | s->pool[s->n_pool++] = desc->addr; | |
240 | ||
241 | if (!qemu_sendv_packet_async(&s->nc, &iov, 1, | |
242 | af_xdp_send_completed)) { | |
243 | /* | |
244 | * The peer does not receive anymore. Packet is queued, stop | |
245 | * reading from the backend until af_xdp_send_completed(). | |
246 | */ | |
247 | af_xdp_read_poll(s, false); | |
248 | ||
249 | /* Return unused descriptors to not break the ring cache. */ | |
250 | xsk_ring_cons__cancel(&s->rx, n_rx - i - 1); | |
251 | n_rx = i + 1; | |
252 | break; | |
253 | } | |
254 | } | |
255 | ||
256 | /* Release actually sent descriptors and try to re-fill. */ | |
257 | xsk_ring_cons__release(&s->rx, n_rx); | |
258 | af_xdp_fq_refill(s, AF_XDP_BATCH_SIZE); | |
259 | } | |
260 | ||
261 | /* Flush and close. */ | |
262 | static void af_xdp_cleanup(NetClientState *nc) | |
263 | { | |
264 | AFXDPState *s = DO_UPCAST(AFXDPState, nc, nc); | |
265 | ||
266 | qemu_purge_queued_packets(nc); | |
267 | ||
268 | af_xdp_poll(nc, false); | |
269 | ||
270 | xsk_socket__delete(s->xsk); | |
271 | s->xsk = NULL; | |
272 | g_free(s->pool); | |
273 | s->pool = NULL; | |
274 | xsk_umem__delete(s->umem); | |
275 | s->umem = NULL; | |
276 | qemu_vfree(s->buffer); | |
277 | s->buffer = NULL; | |
278 | ||
279 | /* Remove the program if it's the last open queue. */ | |
280 | if (!s->inhibit && nc->queue_index == s->n_queues - 1 && s->xdp_flags | |
281 | && bpf_xdp_detach(s->ifindex, s->xdp_flags, NULL) != 0) { | |
282 | fprintf(stderr, | |
283 | "af-xdp: unable to remove XDP program from '%s', ifindex: %d\n", | |
284 | s->ifname, s->ifindex); | |
285 | } | |
286 | } | |
287 | ||
288 | static int af_xdp_umem_create(AFXDPState *s, int sock_fd, Error **errp) | |
289 | { | |
290 | struct xsk_umem_config config = { | |
291 | .fill_size = XSK_RING_PROD__DEFAULT_NUM_DESCS, | |
292 | .comp_size = XSK_RING_CONS__DEFAULT_NUM_DESCS, | |
293 | .frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE, | |
294 | .frame_headroom = 0, | |
295 | }; | |
296 | uint64_t n_descs; | |
297 | uint64_t size; | |
298 | int64_t i; | |
299 | int ret; | |
300 | ||
301 | /* Number of descriptors if all 4 queues (rx, tx, cq, fq) are full. */ | |
302 | n_descs = (XSK_RING_PROD__DEFAULT_NUM_DESCS | |
303 | + XSK_RING_CONS__DEFAULT_NUM_DESCS) * 2; | |
304 | size = n_descs * XSK_UMEM__DEFAULT_FRAME_SIZE; | |
305 | ||
306 | s->buffer = qemu_memalign(qemu_real_host_page_size(), size); | |
307 | memset(s->buffer, 0, size); | |
308 | ||
309 | if (sock_fd < 0) { | |
310 | ret = xsk_umem__create(&s->umem, s->buffer, size, | |
311 | &s->fq, &s->cq, &config); | |
312 | } else { | |
313 | ret = xsk_umem__create_with_fd(&s->umem, sock_fd, s->buffer, size, | |
314 | &s->fq, &s->cq, &config); | |
315 | } | |
316 | ||
317 | if (ret) { | |
318 | qemu_vfree(s->buffer); | |
319 | error_setg_errno(errp, errno, | |
320 | "failed to create umem for %s queue_index: %d", | |
321 | s->ifname, s->nc.queue_index); | |
322 | return -1; | |
323 | } | |
324 | ||
325 | s->pool = g_new(uint64_t, n_descs); | |
326 | /* Fill the pool in the opposite order, because it's a LIFO queue. */ | |
327 | for (i = n_descs; i >= 0; i--) { | |
328 | s->pool[i] = i * XSK_UMEM__DEFAULT_FRAME_SIZE; | |
329 | } | |
330 | s->n_pool = n_descs; | |
331 | ||
332 | af_xdp_fq_refill(s, XSK_RING_PROD__DEFAULT_NUM_DESCS); | |
333 | ||
334 | return 0; | |
335 | } | |
336 | ||
337 | static int af_xdp_socket_create(AFXDPState *s, | |
338 | const NetdevAFXDPOptions *opts, Error **errp) | |
339 | { | |
340 | struct xsk_socket_config cfg = { | |
341 | .rx_size = XSK_RING_CONS__DEFAULT_NUM_DESCS, | |
342 | .tx_size = XSK_RING_PROD__DEFAULT_NUM_DESCS, | |
343 | .libxdp_flags = 0, | |
344 | .bind_flags = XDP_USE_NEED_WAKEUP, | |
345 | .xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST, | |
346 | }; | |
347 | int queue_id, error = 0; | |
348 | ||
349 | s->inhibit = opts->has_inhibit && opts->inhibit; | |
350 | if (s->inhibit) { | |
351 | cfg.libxdp_flags |= XSK_LIBXDP_FLAGS__INHIBIT_PROG_LOAD; | |
352 | } | |
353 | ||
354 | if (opts->has_force_copy && opts->force_copy) { | |
355 | cfg.bind_flags |= XDP_COPY; | |
356 | } | |
357 | ||
358 | queue_id = s->nc.queue_index; | |
359 | if (opts->has_start_queue && opts->start_queue > 0) { | |
360 | queue_id += opts->start_queue; | |
361 | } | |
362 | ||
363 | if (opts->has_mode) { | |
364 | /* Specific mode requested. */ | |
365 | cfg.xdp_flags |= (opts->mode == AFXDP_MODE_NATIVE) | |
366 | ? XDP_FLAGS_DRV_MODE : XDP_FLAGS_SKB_MODE; | |
367 | if (xsk_socket__create(&s->xsk, s->ifname, queue_id, | |
368 | s->umem, &s->rx, &s->tx, &cfg)) { | |
369 | error = errno; | |
370 | } | |
371 | } else { | |
372 | /* No mode requested, try native first. */ | |
373 | cfg.xdp_flags |= XDP_FLAGS_DRV_MODE; | |
374 | ||
375 | if (xsk_socket__create(&s->xsk, s->ifname, queue_id, | |
376 | s->umem, &s->rx, &s->tx, &cfg)) { | |
377 | /* Can't use native mode, try skb. */ | |
378 | cfg.xdp_flags &= ~XDP_FLAGS_DRV_MODE; | |
379 | cfg.xdp_flags |= XDP_FLAGS_SKB_MODE; | |
380 | ||
381 | if (xsk_socket__create(&s->xsk, s->ifname, queue_id, | |
382 | s->umem, &s->rx, &s->tx, &cfg)) { | |
383 | error = errno; | |
384 | } | |
385 | } | |
386 | } | |
387 | ||
388 | if (error) { | |
389 | error_setg_errno(errp, error, | |
390 | "failed to create AF_XDP socket for %s queue_id: %d", | |
391 | s->ifname, queue_id); | |
392 | return -1; | |
393 | } | |
394 | ||
395 | s->xdp_flags = cfg.xdp_flags; | |
396 | ||
397 | return 0; | |
398 | } | |
399 | ||
400 | /* NetClientInfo methods. */ | |
401 | static NetClientInfo net_af_xdp_info = { | |
402 | .type = NET_CLIENT_DRIVER_AF_XDP, | |
403 | .size = sizeof(AFXDPState), | |
404 | .receive = af_xdp_receive, | |
405 | .poll = af_xdp_poll, | |
406 | .cleanup = af_xdp_cleanup, | |
407 | }; | |
408 | ||
409 | static int *parse_socket_fds(const char *sock_fds_str, | |
410 | int64_t n_expected, Error **errp) | |
411 | { | |
412 | gchar **substrings = g_strsplit(sock_fds_str, ":", -1); | |
413 | int64_t i, n_sock_fds = g_strv_length(substrings); | |
414 | int *sock_fds = NULL; | |
415 | ||
416 | if (n_sock_fds != n_expected) { | |
417 | error_setg(errp, "expected %"PRIi64" socket fds, got %"PRIi64, | |
418 | n_expected, n_sock_fds); | |
419 | goto exit; | |
420 | } | |
421 | ||
422 | sock_fds = g_new(int, n_sock_fds); | |
423 | ||
424 | for (i = 0; i < n_sock_fds; i++) { | |
425 | sock_fds[i] = monitor_fd_param(monitor_cur(), substrings[i], errp); | |
426 | if (sock_fds[i] < 0) { | |
427 | g_free(sock_fds); | |
428 | sock_fds = NULL; | |
429 | goto exit; | |
430 | } | |
431 | } | |
432 | ||
433 | exit: | |
434 | g_strfreev(substrings); | |
435 | return sock_fds; | |
436 | } | |
437 | ||
438 | /* | |
439 | * The exported init function. | |
440 | * | |
441 | * ... -netdev af-xdp,ifname="..." | |
442 | */ | |
443 | int net_init_af_xdp(const Netdev *netdev, | |
444 | const char *name, NetClientState *peer, Error **errp) | |
445 | { | |
446 | const NetdevAFXDPOptions *opts = &netdev->u.af_xdp; | |
447 | NetClientState *nc, *nc0 = NULL; | |
448 | unsigned int ifindex; | |
449 | uint32_t prog_id = 0; | |
450 | int *sock_fds = NULL; | |
451 | int64_t i, queues; | |
452 | Error *err = NULL; | |
453 | AFXDPState *s; | |
454 | ||
455 | ifindex = if_nametoindex(opts->ifname); | |
456 | if (!ifindex) { | |
457 | error_setg_errno(errp, errno, "failed to get ifindex for '%s'", | |
458 | opts->ifname); | |
459 | return -1; | |
460 | } | |
461 | ||
462 | queues = opts->has_queues ? opts->queues : 1; | |
463 | if (queues < 1) { | |
464 | error_setg(errp, "invalid number of queues (%" PRIi64 ") for '%s'", | |
465 | queues, opts->ifname); | |
466 | return -1; | |
467 | } | |
468 | ||
469 | if ((opts->has_inhibit && opts->inhibit) != !!opts->sock_fds) { | |
470 | error_setg(errp, "'inhibit=on' requires 'sock-fds' and vice versa"); | |
471 | return -1; | |
472 | } | |
473 | ||
474 | if (opts->sock_fds) { | |
475 | sock_fds = parse_socket_fds(opts->sock_fds, queues, errp); | |
476 | if (!sock_fds) { | |
477 | return -1; | |
478 | } | |
479 | } | |
480 | ||
481 | for (i = 0; i < queues; i++) { | |
482 | nc = qemu_new_net_client(&net_af_xdp_info, peer, "af-xdp", name); | |
483 | qemu_set_info_str(nc, "af-xdp%"PRIi64" to %s", i, opts->ifname); | |
484 | nc->queue_index = i; | |
485 | ||
486 | if (!nc0) { | |
487 | nc0 = nc; | |
488 | } | |
489 | ||
490 | s = DO_UPCAST(AFXDPState, nc, nc); | |
491 | ||
492 | pstrcpy(s->ifname, sizeof(s->ifname), opts->ifname); | |
493 | s->ifindex = ifindex; | |
494 | s->n_queues = queues; | |
495 | ||
496 | if (af_xdp_umem_create(s, sock_fds ? sock_fds[i] : -1, errp) | |
497 | || af_xdp_socket_create(s, opts, errp)) { | |
498 | /* Make sure the XDP program will be removed. */ | |
499 | s->n_queues = i; | |
500 | error_propagate(errp, err); | |
501 | goto err; | |
502 | } | |
503 | } | |
504 | ||
505 | if (nc0) { | |
506 | s = DO_UPCAST(AFXDPState, nc, nc0); | |
507 | if (bpf_xdp_query_id(s->ifindex, s->xdp_flags, &prog_id) || !prog_id) { | |
508 | error_setg_errno(errp, errno, | |
509 | "no XDP program loaded on '%s', ifindex: %d", | |
510 | s->ifname, s->ifindex); | |
511 | goto err; | |
512 | } | |
513 | } | |
514 | ||
515 | af_xdp_read_poll(s, true); /* Initially only poll for reads. */ | |
516 | ||
517 | return 0; | |
518 | ||
519 | err: | |
520 | g_free(sock_fds); | |
521 | if (nc0) { | |
522 | qemu_del_net_client(nc0); | |
523 | } | |
524 | ||
525 | return -1; | |
526 | } |