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1// SPDX-License-Identifier: GPL-2.0-only
2/* bpf/cpumap.c
3 *
4 * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
5 */
6
7/**
8 * DOC: cpu map
9 * The 'cpumap' is primarily used as a backend map for XDP BPF helper
10 * call bpf_redirect_map() and XDP_REDIRECT action, like 'devmap'.
11 *
12 * Unlike devmap which redirects XDP frames out to another NIC device,
13 * this map type redirects raw XDP frames to another CPU. The remote
14 * CPU will do SKB-allocation and call the normal network stack.
15 */
16/*
17 * This is a scalability and isolation mechanism, that allow
18 * separating the early driver network XDP layer, from the rest of the
19 * netstack, and assigning dedicated CPUs for this stage. This
20 * basically allows for 10G wirespeed pre-filtering via bpf.
21 */
22#include <linux/bitops.h>
23#include <linux/bpf.h>
24#include <linux/filter.h>
25#include <linux/ptr_ring.h>
26#include <net/xdp.h>
27
28#include <linux/sched.h>
29#include <linux/workqueue.h>
30#include <linux/kthread.h>
31#include <linux/completion.h>
32#include <trace/events/xdp.h>
33#include <linux/btf_ids.h>
34
35#include <linux/netdevice.h> /* netif_receive_skb_list */
36#include <linux/etherdevice.h> /* eth_type_trans */
37
38/* General idea: XDP packets getting XDP redirected to another CPU,
39 * will maximum be stored/queued for one driver ->poll() call. It is
40 * guaranteed that queueing the frame and the flush operation happen on
41 * same CPU. Thus, cpu_map_flush operation can deduct via this_cpu_ptr()
42 * which queue in bpf_cpu_map_entry contains packets.
43 */
44
45#define CPU_MAP_BULK_SIZE 8 /* 8 == one cacheline on 64-bit archs */
46struct bpf_cpu_map_entry;
47struct bpf_cpu_map;
48
49struct xdp_bulk_queue {
50 void *q[CPU_MAP_BULK_SIZE];
51 struct list_head flush_node;
52 struct bpf_cpu_map_entry *obj;
53 unsigned int count;
54};
55
56/* Struct for every remote "destination" CPU in map */
57struct bpf_cpu_map_entry {
58 u32 cpu; /* kthread CPU and map index */
59 int map_id; /* Back reference to map */
60
61 /* XDP can run multiple RX-ring queues, need __percpu enqueue store */
62 struct xdp_bulk_queue __percpu *bulkq;
63
64 /* Queue with potential multi-producers, and single-consumer kthread */
65 struct ptr_ring *queue;
66 struct task_struct *kthread;
67
68 struct bpf_cpumap_val value;
69 struct bpf_prog *prog;
70
71 struct completion kthread_running;
72 struct rcu_work free_work;
73};
74
75struct bpf_cpu_map {
76 struct bpf_map map;
77 /* Below members specific for map type */
78 struct bpf_cpu_map_entry __rcu **cpu_map;
79};
80
81static DEFINE_PER_CPU(struct list_head, cpu_map_flush_list);
82
83static struct bpf_map *cpu_map_alloc(union bpf_attr *attr)
84{
85 u32 value_size = attr->value_size;
86 struct bpf_cpu_map *cmap;
87
88 /* check sanity of attributes */
89 if (attr->max_entries == 0 || attr->key_size != 4 ||
90 (value_size != offsetofend(struct bpf_cpumap_val, qsize) &&
91 value_size != offsetofend(struct bpf_cpumap_val, bpf_prog.fd)) ||
92 attr->map_flags & ~BPF_F_NUMA_NODE)
93 return ERR_PTR(-EINVAL);
94
95 /* Pre-limit array size based on NR_CPUS, not final CPU check */
96 if (attr->max_entries > NR_CPUS)
97 return ERR_PTR(-E2BIG);
98
99 cmap = bpf_map_area_alloc(sizeof(*cmap), NUMA_NO_NODE);
100 if (!cmap)
101 return ERR_PTR(-ENOMEM);
102
103 bpf_map_init_from_attr(&cmap->map, attr);
104
105 /* Alloc array for possible remote "destination" CPUs */
106 cmap->cpu_map = bpf_map_area_alloc(cmap->map.max_entries *
107 sizeof(struct bpf_cpu_map_entry *),
108 cmap->map.numa_node);
109 if (!cmap->cpu_map) {
110 bpf_map_area_free(cmap);
111 return ERR_PTR(-ENOMEM);
112 }
113
114 return &cmap->map;
115}
116
117static void __cpu_map_ring_cleanup(struct ptr_ring *ring)
118{
119 /* The tear-down procedure should have made sure that queue is
120 * empty. See __cpu_map_entry_replace() and work-queue
121 * invoked cpu_map_kthread_stop(). Catch any broken behaviour
122 * gracefully and warn once.
123 */
124 void *ptr;
125
126 while ((ptr = ptr_ring_consume(ring))) {
127 WARN_ON_ONCE(1);
128 if (unlikely(__ptr_test_bit(0, &ptr))) {
129 __ptr_clear_bit(0, &ptr);
130 kfree_skb(ptr);
131 continue;
132 }
133 xdp_return_frame(ptr);
134 }
135}
136
137static void cpu_map_bpf_prog_run_skb(struct bpf_cpu_map_entry *rcpu,
138 struct list_head *listp,
139 struct xdp_cpumap_stats *stats)
140{
141 struct sk_buff *skb, *tmp;
142 struct xdp_buff xdp;
143 u32 act;
144 int err;
145
146 list_for_each_entry_safe(skb, tmp, listp, list) {
147 act = bpf_prog_run_generic_xdp(skb, &xdp, rcpu->prog);
148 switch (act) {
149 case XDP_PASS:
150 break;
151 case XDP_REDIRECT:
152 skb_list_del_init(skb);
153 err = xdp_do_generic_redirect(skb->dev, skb, &xdp,
154 rcpu->prog);
155 if (unlikely(err)) {
156 kfree_skb(skb);
157 stats->drop++;
158 } else {
159 stats->redirect++;
160 }
161 return;
162 default:
163 bpf_warn_invalid_xdp_action(NULL, rcpu->prog, act);
164 fallthrough;
165 case XDP_ABORTED:
166 trace_xdp_exception(skb->dev, rcpu->prog, act);
167 fallthrough;
168 case XDP_DROP:
169 skb_list_del_init(skb);
170 kfree_skb(skb);
171 stats->drop++;
172 return;
173 }
174 }
175}
176
177static int cpu_map_bpf_prog_run_xdp(struct bpf_cpu_map_entry *rcpu,
178 void **frames, int n,
179 struct xdp_cpumap_stats *stats)
180{
181 struct xdp_rxq_info rxq = {};
182 struct xdp_buff xdp;
183 int i, nframes = 0;
184
185 xdp_set_return_frame_no_direct();
186 xdp.rxq = &rxq;
187
188 for (i = 0; i < n; i++) {
189 struct xdp_frame *xdpf = frames[i];
190 u32 act;
191 int err;
192
193 rxq.dev = xdpf->dev_rx;
194 rxq.mem = xdpf->mem;
195 /* TODO: report queue_index to xdp_rxq_info */
196
197 xdp_convert_frame_to_buff(xdpf, &xdp);
198
199 act = bpf_prog_run_xdp(rcpu->prog, &xdp);
200 switch (act) {
201 case XDP_PASS:
202 err = xdp_update_frame_from_buff(&xdp, xdpf);
203 if (err < 0) {
204 xdp_return_frame(xdpf);
205 stats->drop++;
206 } else {
207 frames[nframes++] = xdpf;
208 stats->pass++;
209 }
210 break;
211 case XDP_REDIRECT:
212 err = xdp_do_redirect(xdpf->dev_rx, &xdp,
213 rcpu->prog);
214 if (unlikely(err)) {
215 xdp_return_frame(xdpf);
216 stats->drop++;
217 } else {
218 stats->redirect++;
219 }
220 break;
221 default:
222 bpf_warn_invalid_xdp_action(NULL, rcpu->prog, act);
223 fallthrough;
224 case XDP_DROP:
225 xdp_return_frame(xdpf);
226 stats->drop++;
227 break;
228 }
229 }
230
231 xdp_clear_return_frame_no_direct();
232
233 return nframes;
234}
235
236#define CPUMAP_BATCH 8
237
238static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entry *rcpu, void **frames,
239 int xdp_n, struct xdp_cpumap_stats *stats,
240 struct list_head *list)
241{
242 int nframes;
243
244 if (!rcpu->prog)
245 return xdp_n;
246
247 rcu_read_lock_bh();
248
249 nframes = cpu_map_bpf_prog_run_xdp(rcpu, frames, xdp_n, stats);
250
251 if (stats->redirect)
252 xdp_do_flush();
253
254 if (unlikely(!list_empty(list)))
255 cpu_map_bpf_prog_run_skb(rcpu, list, stats);
256
257 rcu_read_unlock_bh(); /* resched point, may call do_softirq() */
258
259 return nframes;
260}
261
262static int cpu_map_kthread_run(void *data)
263{
264 struct bpf_cpu_map_entry *rcpu = data;
265
266 complete(&rcpu->kthread_running);
267 set_current_state(TASK_INTERRUPTIBLE);
268
269 /* When kthread gives stop order, then rcpu have been disconnected
270 * from map, thus no new packets can enter. Remaining in-flight
271 * per CPU stored packets are flushed to this queue. Wait honoring
272 * kthread_stop signal until queue is empty.
273 */
274 while (!kthread_should_stop() || !__ptr_ring_empty(rcpu->queue)) {
275 struct xdp_cpumap_stats stats = {}; /* zero stats */
276 unsigned int kmem_alloc_drops = 0, sched = 0;
277 gfp_t gfp = __GFP_ZERO | GFP_ATOMIC;
278 int i, n, m, nframes, xdp_n;
279 void *frames[CPUMAP_BATCH];
280 void *skbs[CPUMAP_BATCH];
281 LIST_HEAD(list);
282
283 /* Release CPU reschedule checks */
284 if (__ptr_ring_empty(rcpu->queue)) {
285 set_current_state(TASK_INTERRUPTIBLE);
286 /* Recheck to avoid lost wake-up */
287 if (__ptr_ring_empty(rcpu->queue)) {
288 schedule();
289 sched = 1;
290 } else {
291 __set_current_state(TASK_RUNNING);
292 }
293 } else {
294 sched = cond_resched();
295 }
296
297 /*
298 * The bpf_cpu_map_entry is single consumer, with this
299 * kthread CPU pinned. Lockless access to ptr_ring
300 * consume side valid as no-resize allowed of queue.
301 */
302 n = __ptr_ring_consume_batched(rcpu->queue, frames,
303 CPUMAP_BATCH);
304 for (i = 0, xdp_n = 0; i < n; i++) {
305 void *f = frames[i];
306 struct page *page;
307
308 if (unlikely(__ptr_test_bit(0, &f))) {
309 struct sk_buff *skb = f;
310
311 __ptr_clear_bit(0, &skb);
312 list_add_tail(&skb->list, &list);
313 continue;
314 }
315
316 frames[xdp_n++] = f;
317 page = virt_to_page(f);
318
319 /* Bring struct page memory area to curr CPU. Read by
320 * build_skb_around via page_is_pfmemalloc(), and when
321 * freed written by page_frag_free call.
322 */
323 prefetchw(page);
324 }
325
326 /* Support running another XDP prog on this CPU */
327 nframes = cpu_map_bpf_prog_run(rcpu, frames, xdp_n, &stats, &list);
328 if (nframes) {
329 m = kmem_cache_alloc_bulk(skbuff_cache, gfp, nframes, skbs);
330 if (unlikely(m == 0)) {
331 for (i = 0; i < nframes; i++)
332 skbs[i] = NULL; /* effect: xdp_return_frame */
333 kmem_alloc_drops += nframes;
334 }
335 }
336
337 local_bh_disable();
338 for (i = 0; i < nframes; i++) {
339 struct xdp_frame *xdpf = frames[i];
340 struct sk_buff *skb = skbs[i];
341
342 skb = __xdp_build_skb_from_frame(xdpf, skb,
343 xdpf->dev_rx);
344 if (!skb) {
345 xdp_return_frame(xdpf);
346 continue;
347 }
348
349 list_add_tail(&skb->list, &list);
350 }
351 netif_receive_skb_list(&list);
352
353 /* Feedback loop via tracepoint */
354 trace_xdp_cpumap_kthread(rcpu->map_id, n, kmem_alloc_drops,
355 sched, &stats);
356
357 local_bh_enable(); /* resched point, may call do_softirq() */
358 }
359 __set_current_state(TASK_RUNNING);
360
361 return 0;
362}
363
364static int __cpu_map_load_bpf_program(struct bpf_cpu_map_entry *rcpu,
365 struct bpf_map *map, int fd)
366{
367 struct bpf_prog *prog;
368
369 prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_XDP);
370 if (IS_ERR(prog))
371 return PTR_ERR(prog);
372
373 if (prog->expected_attach_type != BPF_XDP_CPUMAP ||
374 !bpf_prog_map_compatible(map, prog)) {
375 bpf_prog_put(prog);
376 return -EINVAL;
377 }
378
379 rcpu->value.bpf_prog.id = prog->aux->id;
380 rcpu->prog = prog;
381
382 return 0;
383}
384
385static struct bpf_cpu_map_entry *
386__cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value,
387 u32 cpu)
388{
389 int numa, err, i, fd = value->bpf_prog.fd;
390 gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
391 struct bpf_cpu_map_entry *rcpu;
392 struct xdp_bulk_queue *bq;
393
394 /* Have map->numa_node, but choose node of redirect target CPU */
395 numa = cpu_to_node(cpu);
396
397 rcpu = bpf_map_kmalloc_node(map, sizeof(*rcpu), gfp | __GFP_ZERO, numa);
398 if (!rcpu)
399 return NULL;
400
401 /* Alloc percpu bulkq */
402 rcpu->bulkq = bpf_map_alloc_percpu(map, sizeof(*rcpu->bulkq),
403 sizeof(void *), gfp);
404 if (!rcpu->bulkq)
405 goto free_rcu;
406
407 for_each_possible_cpu(i) {
408 bq = per_cpu_ptr(rcpu->bulkq, i);
409 bq->obj = rcpu;
410 }
411
412 /* Alloc queue */
413 rcpu->queue = bpf_map_kmalloc_node(map, sizeof(*rcpu->queue), gfp,
414 numa);
415 if (!rcpu->queue)
416 goto free_bulkq;
417
418 err = ptr_ring_init(rcpu->queue, value->qsize, gfp);
419 if (err)
420 goto free_queue;
421
422 rcpu->cpu = cpu;
423 rcpu->map_id = map->id;
424 rcpu->value.qsize = value->qsize;
425
426 if (fd > 0 && __cpu_map_load_bpf_program(rcpu, map, fd))
427 goto free_ptr_ring;
428
429 /* Setup kthread */
430 init_completion(&rcpu->kthread_running);
431 rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa,
432 "cpumap/%d/map:%d", cpu,
433 map->id);
434 if (IS_ERR(rcpu->kthread))
435 goto free_prog;
436
437 /* Make sure kthread runs on a single CPU */
438 kthread_bind(rcpu->kthread, cpu);
439 wake_up_process(rcpu->kthread);
440
441 /* Make sure kthread has been running, so kthread_stop() will not
442 * stop the kthread prematurely and all pending frames or skbs
443 * will be handled by the kthread before kthread_stop() returns.
444 */
445 wait_for_completion(&rcpu->kthread_running);
446
447 return rcpu;
448
449free_prog:
450 if (rcpu->prog)
451 bpf_prog_put(rcpu->prog);
452free_ptr_ring:
453 ptr_ring_cleanup(rcpu->queue, NULL);
454free_queue:
455 kfree(rcpu->queue);
456free_bulkq:
457 free_percpu(rcpu->bulkq);
458free_rcu:
459 kfree(rcpu);
460 return NULL;
461}
462
463static void __cpu_map_entry_free(struct work_struct *work)
464{
465 struct bpf_cpu_map_entry *rcpu;
466
467 /* This cpu_map_entry have been disconnected from map and one
468 * RCU grace-period have elapsed. Thus, XDP cannot queue any
469 * new packets and cannot change/set flush_needed that can
470 * find this entry.
471 */
472 rcpu = container_of(to_rcu_work(work), struct bpf_cpu_map_entry, free_work);
473
474 /* kthread_stop will wake_up_process and wait for it to complete.
475 * cpu_map_kthread_run() makes sure the pointer ring is empty
476 * before exiting.
477 */
478 kthread_stop(rcpu->kthread);
479
480 if (rcpu->prog)
481 bpf_prog_put(rcpu->prog);
482 /* The queue should be empty at this point */
483 __cpu_map_ring_cleanup(rcpu->queue);
484 ptr_ring_cleanup(rcpu->queue, NULL);
485 kfree(rcpu->queue);
486 free_percpu(rcpu->bulkq);
487 kfree(rcpu);
488}
489
490/* After the xchg of the bpf_cpu_map_entry pointer, we need to make sure the old
491 * entry is no longer in use before freeing. We use queue_rcu_work() to call
492 * __cpu_map_entry_free() in a separate workqueue after waiting for an RCU grace
493 * period. This means that (a) all pending enqueue and flush operations have
494 * completed (because of the RCU callback), and (b) we are in a workqueue
495 * context where we can stop the kthread and wait for it to exit before freeing
496 * everything.
497 */
498static void __cpu_map_entry_replace(struct bpf_cpu_map *cmap,
499 u32 key_cpu, struct bpf_cpu_map_entry *rcpu)
500{
501 struct bpf_cpu_map_entry *old_rcpu;
502
503 old_rcpu = unrcu_pointer(xchg(&cmap->cpu_map[key_cpu], RCU_INITIALIZER(rcpu)));
504 if (old_rcpu) {
505 INIT_RCU_WORK(&old_rcpu->free_work, __cpu_map_entry_free);
506 queue_rcu_work(system_wq, &old_rcpu->free_work);
507 }
508}
509
510static long cpu_map_delete_elem(struct bpf_map *map, void *key)
511{
512 struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
513 u32 key_cpu = *(u32 *)key;
514
515 if (key_cpu >= map->max_entries)
516 return -EINVAL;
517
518 /* notice caller map_delete_elem() uses rcu_read_lock() */
519 __cpu_map_entry_replace(cmap, key_cpu, NULL);
520 return 0;
521}
522
523static long cpu_map_update_elem(struct bpf_map *map, void *key, void *value,
524 u64 map_flags)
525{
526 struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
527 struct bpf_cpumap_val cpumap_value = {};
528 struct bpf_cpu_map_entry *rcpu;
529 /* Array index key correspond to CPU number */
530 u32 key_cpu = *(u32 *)key;
531
532 memcpy(&cpumap_value, value, map->value_size);
533
534 if (unlikely(map_flags > BPF_EXIST))
535 return -EINVAL;
536 if (unlikely(key_cpu >= cmap->map.max_entries))
537 return -E2BIG;
538 if (unlikely(map_flags == BPF_NOEXIST))
539 return -EEXIST;
540 if (unlikely(cpumap_value.qsize > 16384)) /* sanity limit on qsize */
541 return -EOVERFLOW;
542
543 /* Make sure CPU is a valid possible cpu */
544 if (key_cpu >= nr_cpumask_bits || !cpu_possible(key_cpu))
545 return -ENODEV;
546
547 if (cpumap_value.qsize == 0) {
548 rcpu = NULL; /* Same as deleting */
549 } else {
550 /* Updating qsize cause re-allocation of bpf_cpu_map_entry */
551 rcpu = __cpu_map_entry_alloc(map, &cpumap_value, key_cpu);
552 if (!rcpu)
553 return -ENOMEM;
554 }
555 rcu_read_lock();
556 __cpu_map_entry_replace(cmap, key_cpu, rcpu);
557 rcu_read_unlock();
558 return 0;
559}
560
561static void cpu_map_free(struct bpf_map *map)
562{
563 struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
564 u32 i;
565
566 /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
567 * so the bpf programs (can be more than one that used this map) were
568 * disconnected from events. Wait for outstanding critical sections in
569 * these programs to complete. synchronize_rcu() below not only
570 * guarantees no further "XDP/bpf-side" reads against
571 * bpf_cpu_map->cpu_map, but also ensure pending flush operations
572 * (if any) are completed.
573 */
574 synchronize_rcu();
575
576 /* The only possible user of bpf_cpu_map_entry is
577 * cpu_map_kthread_run().
578 */
579 for (i = 0; i < cmap->map.max_entries; i++) {
580 struct bpf_cpu_map_entry *rcpu;
581
582 rcpu = rcu_dereference_raw(cmap->cpu_map[i]);
583 if (!rcpu)
584 continue;
585
586 /* Stop kthread and cleanup entry directly */
587 __cpu_map_entry_free(&rcpu->free_work.work);
588 }
589 bpf_map_area_free(cmap->cpu_map);
590 bpf_map_area_free(cmap);
591}
592
593/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
594 * by local_bh_disable() (from XDP calls inside NAPI). The
595 * rcu_read_lock_bh_held() below makes lockdep accept both.
596 */
597static void *__cpu_map_lookup_elem(struct bpf_map *map, u32 key)
598{
599 struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
600 struct bpf_cpu_map_entry *rcpu;
601
602 if (key >= map->max_entries)
603 return NULL;
604
605 rcpu = rcu_dereference_check(cmap->cpu_map[key],
606 rcu_read_lock_bh_held());
607 return rcpu;
608}
609
610static void *cpu_map_lookup_elem(struct bpf_map *map, void *key)
611{
612 struct bpf_cpu_map_entry *rcpu =
613 __cpu_map_lookup_elem(map, *(u32 *)key);
614
615 return rcpu ? &rcpu->value : NULL;
616}
617
618static int cpu_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
619{
620 struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
621 u32 index = key ? *(u32 *)key : U32_MAX;
622 u32 *next = next_key;
623
624 if (index >= cmap->map.max_entries) {
625 *next = 0;
626 return 0;
627 }
628
629 if (index == cmap->map.max_entries - 1)
630 return -ENOENT;
631 *next = index + 1;
632 return 0;
633}
634
635static long cpu_map_redirect(struct bpf_map *map, u64 index, u64 flags)
636{
637 return __bpf_xdp_redirect_map(map, index, flags, 0,
638 __cpu_map_lookup_elem);
639}
640
641static u64 cpu_map_mem_usage(const struct bpf_map *map)
642{
643 u64 usage = sizeof(struct bpf_cpu_map);
644
645 /* Currently the dynamically allocated elements are not counted */
646 usage += (u64)map->max_entries * sizeof(struct bpf_cpu_map_entry *);
647 return usage;
648}
649
650BTF_ID_LIST_SINGLE(cpu_map_btf_ids, struct, bpf_cpu_map)
651const struct bpf_map_ops cpu_map_ops = {
652 .map_meta_equal = bpf_map_meta_equal,
653 .map_alloc = cpu_map_alloc,
654 .map_free = cpu_map_free,
655 .map_delete_elem = cpu_map_delete_elem,
656 .map_update_elem = cpu_map_update_elem,
657 .map_lookup_elem = cpu_map_lookup_elem,
658 .map_get_next_key = cpu_map_get_next_key,
659 .map_check_btf = map_check_no_btf,
660 .map_mem_usage = cpu_map_mem_usage,
661 .map_btf_id = &cpu_map_btf_ids[0],
662 .map_redirect = cpu_map_redirect,
663};
664
665static void bq_flush_to_queue(struct xdp_bulk_queue *bq)
666{
667 struct bpf_cpu_map_entry *rcpu = bq->obj;
668 unsigned int processed = 0, drops = 0;
669 const int to_cpu = rcpu->cpu;
670 struct ptr_ring *q;
671 int i;
672
673 if (unlikely(!bq->count))
674 return;
675
676 q = rcpu->queue;
677 spin_lock(&q->producer_lock);
678
679 for (i = 0; i < bq->count; i++) {
680 struct xdp_frame *xdpf = bq->q[i];
681 int err;
682
683 err = __ptr_ring_produce(q, xdpf);
684 if (err) {
685 drops++;
686 xdp_return_frame_rx_napi(xdpf);
687 }
688 processed++;
689 }
690 bq->count = 0;
691 spin_unlock(&q->producer_lock);
692
693 __list_del_clearprev(&bq->flush_node);
694
695 /* Feedback loop via tracepoints */
696 trace_xdp_cpumap_enqueue(rcpu->map_id, processed, drops, to_cpu);
697}
698
699/* Runs under RCU-read-side, plus in softirq under NAPI protection.
700 * Thus, safe percpu variable access.
701 */
702static void bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf)
703{
704 struct list_head *flush_list = this_cpu_ptr(&cpu_map_flush_list);
705 struct xdp_bulk_queue *bq = this_cpu_ptr(rcpu->bulkq);
706
707 if (unlikely(bq->count == CPU_MAP_BULK_SIZE))
708 bq_flush_to_queue(bq);
709
710 /* Notice, xdp_buff/page MUST be queued here, long enough for
711 * driver to code invoking us to finished, due to driver
712 * (e.g. ixgbe) recycle tricks based on page-refcnt.
713 *
714 * Thus, incoming xdp_frame is always queued here (else we race
715 * with another CPU on page-refcnt and remaining driver code).
716 * Queue time is very short, as driver will invoke flush
717 * operation, when completing napi->poll call.
718 */
719 bq->q[bq->count++] = xdpf;
720
721 if (!bq->flush_node.prev)
722 list_add(&bq->flush_node, flush_list);
723}
724
725int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf,
726 struct net_device *dev_rx)
727{
728 /* Info needed when constructing SKB on remote CPU */
729 xdpf->dev_rx = dev_rx;
730
731 bq_enqueue(rcpu, xdpf);
732 return 0;
733}
734
735int cpu_map_generic_redirect(struct bpf_cpu_map_entry *rcpu,
736 struct sk_buff *skb)
737{
738 int ret;
739
740 __skb_pull(skb, skb->mac_len);
741 skb_set_redirected(skb, false);
742 __ptr_set_bit(0, &skb);
743
744 ret = ptr_ring_produce(rcpu->queue, skb);
745 if (ret < 0)
746 goto trace;
747
748 wake_up_process(rcpu->kthread);
749trace:
750 trace_xdp_cpumap_enqueue(rcpu->map_id, !ret, !!ret, rcpu->cpu);
751 return ret;
752}
753
754void __cpu_map_flush(void)
755{
756 struct list_head *flush_list = this_cpu_ptr(&cpu_map_flush_list);
757 struct xdp_bulk_queue *bq, *tmp;
758
759 list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
760 bq_flush_to_queue(bq);
761
762 /* If already running, costs spin_lock_irqsave + smb_mb */
763 wake_up_process(bq->obj->kthread);
764 }
765}
766
767#ifdef CONFIG_DEBUG_NET
768bool cpu_map_check_flush(void)
769{
770 if (list_empty(this_cpu_ptr(&cpu_map_flush_list)))
771 return false;
772 __cpu_map_flush();
773 return true;
774}
775#endif
776
777static int __init cpu_map_init(void)
778{
779 int cpu;
780
781 for_each_possible_cpu(cpu)
782 INIT_LIST_HEAD(&per_cpu(cpu_map_flush_list, cpu));
783 return 0;
784}
785
786subsys_initcall(cpu_map_init);