net/core/xdp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* net/core/xdp.c
   3  *
   4  * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
   5  */
   6 #include <linux/bpf.h>
   7 #include <linux/filter.h>
   8 #include <linux/types.h>
   9 #include <linux/mm.h>
  10 #include <linux/netdevice.h>
  11 #include <linux/slab.h>
  12 #include <linux/idr.h>
  13 #include <linux/rhashtable.h>
  14 #include <net/page_pool.h>
  15
  16 #include <net/xdp.h>
  17 #include <net/xdp_priv.h> /* struct xdp_mem_allocator */
  18 #include <trace/events/xdp.h>
  19
  20 #define REG_STATE_NEW           0x0
  21 #define REG_STATE_REGISTERED    0x1
  22 #define REG_STATE_UNREGISTERED  0x2
  23 #define REG_STATE_UNUSED        0x3
  24
  25 static DEFINE_IDA(mem_id_pool);
  26 static DEFINE_MUTEX(mem_id_lock);
  27 #define MEM_ID_MAX 0xFFFE
  28 #define MEM_ID_MIN 1
  29 static int mem_id_next = MEM_ID_MIN;
  30
  31 static bool mem_id_init; /* false */
  32 static struct rhashtable *mem_id_ht;
  33
  34 static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
  35 {
  36         const u32 *k = data;
  37         const u32 key = *k;
  38
  39         BUILD_BUG_ON(sizeof_field(struct xdp_mem_allocator, mem.id)
  40                      != sizeof(u32));
  41
  42         /* Use cyclic increasing ID as direct hash key */
  43         return key;
  44 }
  45
  46 static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,
  47                           const void *ptr)
  48 {
  49         const struct xdp_mem_allocator *xa = ptr;
  50         u32 mem_id = *(u32 *)arg->key;
  51
  52         return xa->mem.id != mem_id;
  53 }
  54
  55 static const struct rhashtable_params mem_id_rht_params = {
  56         .nelem_hint = 64,
  57         .head_offset = offsetof(struct xdp_mem_allocator, node),
  58         .key_offset  = offsetof(struct xdp_mem_allocator, mem.id),
  59         .key_len = sizeof_field(struct xdp_mem_allocator, mem.id),
  60         .max_size = MEM_ID_MAX,
  61         .min_size = 8,
  62         .automatic_shrinking = true,
  63         .hashfn    = xdp_mem_id_hashfn,
  64         .obj_cmpfn = xdp_mem_id_cmp,
  65 };
  66
  67 static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
  68 {
  69         struct xdp_mem_allocator *xa;
  70
  71         xa = container_of(rcu, struct xdp_mem_allocator, rcu);
  72
  73         /* Allow this ID to be reused */
  74         ida_simple_remove(&mem_id_pool, xa->mem.id);
  75
  76         kfree(xa);
  77 }
  78
  79 static void mem_xa_remove(struct xdp_mem_allocator *xa)
  80 {
  81         trace_mem_disconnect(xa);
  82
  83         if (!rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params))
  84                 call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
  85 }
  86
  87 static void mem_allocator_disconnect(void *allocator)
  88 {
  89         struct xdp_mem_allocator *xa;
  90         struct rhashtable_iter iter;
  91
  92         mutex_lock(&mem_id_lock);
  93
  94         rhashtable_walk_enter(mem_id_ht, &iter);
  95         do {
  96                 rhashtable_walk_start(&iter);
  97
  98                 while ((xa = rhashtable_walk_next(&iter)) && !IS_ERR(xa)) {
  99                         if (xa->allocator == allocator)
 100                                 mem_xa_remove(xa);
 101                 }
 102
 103                 rhashtable_walk_stop(&iter);
 104
 105         } while (xa == ERR_PTR(-EAGAIN));
 106         rhashtable_walk_exit(&iter);
 107
 108         mutex_unlock(&mem_id_lock);
 109 }
 110
 111 static void mem_id_disconnect(int id)
 112 {
 113         struct xdp_mem_allocator *xa;
 114
 115         mutex_lock(&mem_id_lock);
 116
 117         xa = rhashtable_lookup_fast(mem_id_ht, &id, mem_id_rht_params);
 118         if (!xa) {
 119                 mutex_unlock(&mem_id_lock);
 120                 WARN(1, "Request remove non-existing id(%d), driver bug?", id);
 121                 return;
 122         }
 123
 124         trace_mem_disconnect(xa);
 125
 126         if (!rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params))
 127                 call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
 128
 129         mutex_unlock(&mem_id_lock);
 130 }
 131
 132 void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
 133 {
 134         struct xdp_mem_allocator *xa;
 135         int id = xdp_rxq->mem.id;
 136
 137         if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
 138                 WARN(1, "Missing register, driver bug");
 139                 return;
 140         }
 141
 142         if (id == 0)
 143                 return;
 144
 145         if (xdp_rxq->mem.type == MEM_TYPE_ZERO_COPY)
 146                 return mem_id_disconnect(id);
 147
 148         if (xdp_rxq->mem.type == MEM_TYPE_PAGE_POOL) {
 149                 rcu_read_lock();
 150                 xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params);
 151                 page_pool_destroy(xa->page_pool);
 152                 rcu_read_unlock();
 153         }
 154 }
 155 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model);
 156
 157 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
 158 {
 159         /* Simplify driver cleanup code paths, allow unreg "unused" */
 160         if (xdp_rxq->reg_state == REG_STATE_UNUSED)
 161                 return;
 162
 163         WARN(!(xdp_rxq->reg_state == REG_STATE_REGISTERED), "Driver BUG");
 164
 165         xdp_rxq_info_unreg_mem_model(xdp_rxq);
 166
 167         xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
 168         xdp_rxq->dev = NULL;
 169
 170         /* Reset mem info to defaults */
 171         xdp_rxq->mem.id = 0;
 172         xdp_rxq->mem.type = 0;
 173 }
 174 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);
 175
 176 static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
 177 {
 178         memset(xdp_rxq, 0, sizeof(*xdp_rxq));
 179 }
 180
 181 /* Returns 0 on success, negative on failure */
 182 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
 183                      struct net_device *dev, u32 queue_index)
 184 {
 185         if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
 186                 WARN(1, "Driver promised not to register this");
 187                 return -EINVAL;
 188         }
 189
 190         if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
 191                 WARN(1, "Missing unregister, handled but fix driver");
 192                 xdp_rxq_info_unreg(xdp_rxq);
 193         }
 194
 195         if (!dev) {
 196                 WARN(1, "Missing net_device from driver");
 197                 return -ENODEV;
 198         }
 199
 200         /* State either UNREGISTERED or NEW */
 201         xdp_rxq_info_init(xdp_rxq);
 202         xdp_rxq->dev = dev;
 203         xdp_rxq->queue_index = queue_index;
 204
 205         xdp_rxq->reg_state = REG_STATE_REGISTERED;
 206         return 0;
 207 }
 208 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg);
 209
 210 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
 211 {
 212         xdp_rxq->reg_state = REG_STATE_UNUSED;
 213 }
 214 EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);
 215
 216 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
 217 {
 218         return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
 219 }
 220 EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);
 221
 222 static int __mem_id_init_hash_table(void)
 223 {
 224         struct rhashtable *rht;
 225         int ret;
 226
 227         if (unlikely(mem_id_init))
 228                 return 0;
 229
 230         rht = kzalloc(sizeof(*rht), GFP_KERNEL);
 231         if (!rht)
 232                 return -ENOMEM;
 233
 234         ret = rhashtable_init(rht, &mem_id_rht_params);
 235         if (ret < 0) {
 236                 kfree(rht);
 237                 return ret;
 238         }
 239         mem_id_ht = rht;
 240         smp_mb(); /* mutex lock should provide enough pairing */
 241         mem_id_init = true;
 242
 243         return 0;
 244 }
 245
 246 /* Allocate a cyclic ID that maps to allocator pointer.
 247  * See: https://www.kernel.org/doc/html/latest/core-api/idr.html
 248  *
 249  * Caller must lock mem_id_lock.
 250  */
 251 static int __mem_id_cyclic_get(gfp_t gfp)
 252 {
 253         int retries = 1;
 254         int id;
 255
 256 again:
 257         id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp);
 258         if (id < 0) {
 259                 if (id == -ENOSPC) {
 260                         /* Cyclic allocator, reset next id */
 261                         if (retries--) {
 262                                 mem_id_next = MEM_ID_MIN;
 263                                 goto again;
 264                         }
 265                 }
 266                 return id; /* errno */
 267         }
 268         mem_id_next = id + 1;
 269
 270         return id;
 271 }
 272
 273 static bool __is_supported_mem_type(enum xdp_mem_type type)
 274 {
 275         if (type == MEM_TYPE_PAGE_POOL)
 276                 return is_page_pool_compiled_in();
 277
 278         if (type >= MEM_TYPE_MAX)
 279                 return false;
 280
 281         return true;
 282 }
 283
 284 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 285                                enum xdp_mem_type type, void *allocator)
 286 {
 287         struct xdp_mem_allocator *xdp_alloc;
 288         gfp_t gfp = GFP_KERNEL;
 289         int id, errno, ret;
 290         void *ptr;
 291
 292         if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
 293                 WARN(1, "Missing register, driver bug");
 294                 return -EFAULT;
 295         }
 296
 297         if (!__is_supported_mem_type(type))
 298                 return -EOPNOTSUPP;
 299
 300         xdp_rxq->mem.type = type;
 301
 302         if (!allocator) {
 303                 if (type == MEM_TYPE_PAGE_POOL || type == MEM_TYPE_ZERO_COPY)
 304                         return -EINVAL; /* Setup time check page_pool req */
 305                 return 0;
 306         }
 307
 308         /* Delay init of rhashtable to save memory if feature isn't used */
 309         if (!mem_id_init) {
 310                 mutex_lock(&mem_id_lock);
 311                 ret = __mem_id_init_hash_table();
 312                 mutex_unlock(&mem_id_lock);
 313                 if (ret < 0) {
 314                         WARN_ON(1);
 315                         return ret;
 316                 }
 317         }
 318
 319         xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
 320         if (!xdp_alloc)
 321                 return -ENOMEM;
 322
 323         mutex_lock(&mem_id_lock);
 324         id = __mem_id_cyclic_get(gfp);
 325         if (id < 0) {
 326                 errno = id;
 327                 goto err;
 328         }
 329         xdp_rxq->mem.id = id;
 330         xdp_alloc->mem  = xdp_rxq->mem;
 331         xdp_alloc->allocator = allocator;
 332
 333         /* Insert allocator into ID lookup table */
 334         ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
 335         if (IS_ERR(ptr)) {
 336                 ida_simple_remove(&mem_id_pool, xdp_rxq->mem.id);
 337                 xdp_rxq->mem.id = 0;
 338                 errno = PTR_ERR(ptr);
 339                 goto err;
 340         }
 341
 342         if (type == MEM_TYPE_PAGE_POOL)
 343                 page_pool_use_xdp_mem(allocator, mem_allocator_disconnect);
 344
 345         mutex_unlock(&mem_id_lock);
 346
 347         trace_mem_connect(xdp_alloc, xdp_rxq);
 348         return 0;
 349 err:
 350         mutex_unlock(&mem_id_lock);
 351         kfree(xdp_alloc);
 352         return errno;
 353 }
 354 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
 355
 356 /* XDP RX runs under NAPI protection, and in different delivery error
 357  * scenarios (e.g. queue full), it is possible to return the xdp_frame
 358  * while still leveraging this protection.  The @napi_direct boolean
 359  * is used for those calls sites.  Thus, allowing for faster recycling
 360  * of xdp_frames/pages in those cases.
 361  */
 362 static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
 363                          unsigned long handle)
 364 {
 365         struct xdp_mem_allocator *xa;
 366         struct page *page;
 367
 368         switch (mem->type) {
 369         case MEM_TYPE_PAGE_POOL:
 370                 rcu_read_lock();
 371                 /* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
 372                 xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
 373                 page = virt_to_head_page(data);
 374                 napi_direct &= !xdp_return_frame_no_direct();
 375                 page_pool_put_full_page(xa->page_pool, page, napi_direct);
 376                 rcu_read_unlock();
 377                 break;
 378         case MEM_TYPE_PAGE_SHARED:
 379                 page_frag_free(data);
 380                 break;
 381         case MEM_TYPE_PAGE_ORDER0:
 382                 page = virt_to_page(data); /* Assumes order0 page*/
 383                 put_page(page);
 384                 break;
 385         case MEM_TYPE_ZERO_COPY:
 386                 /* NB! Only valid from an xdp_buff! */
 387                 rcu_read_lock();
 388                 /* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
 389                 xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
 390                 xa->zc_alloc->free(xa->zc_alloc, handle);
 391                 rcu_read_unlock();
 392         default:
 393                 /* Not possible, checked in xdp_rxq_info_reg_mem_model() */
 394                 break;
 395         }
 396 }
 397
 398 void xdp_return_frame(struct xdp_frame *xdpf)
 399 {
 400         __xdp_return(xdpf->data, &xdpf->mem, false, 0);
 401 }
 402 EXPORT_SYMBOL_GPL(xdp_return_frame);
 403
 404 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
 405 {
 406         __xdp_return(xdpf->data, &xdpf->mem, true, 0);
 407 }
 408 EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
 409
 410 void xdp_return_buff(struct xdp_buff *xdp)
 411 {
 412         __xdp_return(xdp->data, &xdp->rxq->mem, true, xdp->handle);
 413 }
 414 EXPORT_SYMBOL_GPL(xdp_return_buff);
 415
 416 /* Only called for MEM_TYPE_PAGE_POOL see xdp.h */
 417 void __xdp_release_frame(void *data, struct xdp_mem_info *mem)
 418 {
 419         struct xdp_mem_allocator *xa;
 420         struct page *page;
 421
 422         rcu_read_lock();
 423         xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
 424         page = virt_to_head_page(data);
 425         if (xa)
 426                 page_pool_release_page(xa->page_pool, page);
 427         rcu_read_unlock();
 428 }
 429 EXPORT_SYMBOL_GPL(__xdp_release_frame);
 430
 431 int xdp_attachment_query(struct xdp_attachment_info *info,
 432                          struct netdev_bpf *bpf)
 433 {
 434         bpf->prog_id = info->prog ? info->prog->aux->id : 0;
 435         bpf->prog_flags = info->prog ? info->flags : 0;
 436         return 0;
 437 }
 438 EXPORT_SYMBOL_GPL(xdp_attachment_query);
 439
 440 bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
 441                              struct netdev_bpf *bpf)
 442 {
 443         if (info->prog && (bpf->flags ^ info->flags) & XDP_FLAGS_MODES) {
 444                 NL_SET_ERR_MSG(bpf->extack,
 445                                "program loaded with different flags");
 446                 return false;
 447         }
 448         return true;
 449 }
 450 EXPORT_SYMBOL_GPL(xdp_attachment_flags_ok);
 451
 452 void xdp_attachment_setup(struct xdp_attachment_info *info,
 453                           struct netdev_bpf *bpf)
 454 {
 455         if (info->prog)
 456                 bpf_prog_put(info->prog);
 457         info->prog = bpf->prog;
 458         info->flags = bpf->flags;
 459 }
 460 EXPORT_SYMBOL_GPL(xdp_attachment_setup);
 461
 462 struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)
 463 {
 464         unsigned int metasize, totsize;
 465         void *addr, *data_to_copy;
 466         struct xdp_frame *xdpf;
 467         struct page *page;
 468
 469         /* Clone into a MEM_TYPE_PAGE_ORDER0 xdp_frame. */
 470         metasize = xdp_data_meta_unsupported(xdp) ? 0 :
 471                    xdp->data - xdp->data_meta;
 472         totsize = xdp->data_end - xdp->data + metasize;
 473
 474         if (sizeof(*xdpf) + totsize > PAGE_SIZE)
 475                 return NULL;
 476
 477         page = dev_alloc_page();
 478         if (!page)
 479                 return NULL;
 480
 481         addr = page_to_virt(page);
 482         xdpf = addr;
 483         memset(xdpf, 0, sizeof(*xdpf));
 484
 485         addr += sizeof(*xdpf);
 486         data_to_copy = metasize ? xdp->data_meta : xdp->data;
 487         memcpy(addr, data_to_copy, totsize);
 488
 489         xdpf->data = addr + metasize;
 490         xdpf->len = totsize - metasize;
 491         xdpf->headroom = 0;
 492         xdpf->metasize = metasize;
 493         xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
 494
 495         xdp_return_buff(xdp);
 496         return xdpf;
 497 }
 498 EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);