1 // SPDX-License-Identifier: GPL-2.0 2 /* XDP user-space packet buffer 3 * Copyright(c) 2018 Intel Corporation. 4 */ 5 6 #include <linux/init.h> 7 #include <linux/sched/mm.h> 8 #include <linux/sched/signal.h> 9 #include <linux/sched/task.h> 10 #include <linux/uaccess.h> 11 #include <linux/slab.h> 12 #include <linux/bpf.h> 13 #include <linux/mm.h> 14 #include <linux/netdevice.h> 15 #include <linux/rtnetlink.h> 16 #include <linux/idr.h> 17 18 #include "xdp_umem.h" 19 #include "xsk_queue.h" 20 21 #define XDP_UMEM_MIN_CHUNK_SIZE 2048 22 23 static DEFINE_IDA(umem_ida); 24 25 void xdp_add_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs) 26 { 27 unsigned long flags; 28 29 spin_lock_irqsave(&umem->xsk_list_lock, flags); 30 list_add_rcu(&xs->list, &umem->xsk_list); 31 spin_unlock_irqrestore(&umem->xsk_list_lock, flags); 32 } 33 34 void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs) 35 { 36 unsigned long flags; 37 38 spin_lock_irqsave(&umem->xsk_list_lock, flags); 39 list_del_rcu(&xs->list); 40 spin_unlock_irqrestore(&umem->xsk_list_lock, flags); 41 } 42 43 /* The umem is stored both in the _rx struct and the _tx struct as we do 44 * not know if the device has more tx queues than rx, or the opposite. 45 * This might also change during run time. 46 */ 47 static int xdp_reg_umem_at_qid(struct net_device *dev, struct xdp_umem *umem, 48 u16 queue_id) 49 { 50 if (queue_id >= max_t(unsigned int, 51 dev->real_num_rx_queues, 52 dev->real_num_tx_queues)) 53 return -EINVAL; 54 55 if (queue_id < dev->real_num_rx_queues) 56 dev->_rx[queue_id].umem = umem; 57 if (queue_id < dev->real_num_tx_queues) 58 dev->_tx[queue_id].umem = umem; 59 60 return 0; 61 } 62 63 struct xdp_umem *xdp_get_umem_from_qid(struct net_device *dev, 64 u16 queue_id) 65 { 66 if (queue_id < dev->real_num_rx_queues) 67 return dev->_rx[queue_id].umem; 68 if (queue_id < dev->real_num_tx_queues) 69 return dev->_tx[queue_id].umem; 70 71 return NULL; 72 } 73 EXPORT_SYMBOL(xdp_get_umem_from_qid); 74 75 static void xdp_clear_umem_at_qid(struct net_device *dev, u16 queue_id) 76 { 77 if (queue_id < dev->real_num_rx_queues) 78 dev->_rx[queue_id].umem = NULL; 79 if (queue_id < dev->real_num_tx_queues) 80 dev->_tx[queue_id].umem = NULL; 81 } 82 83 int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev, 84 u16 queue_id, u16 flags) 85 { 86 bool force_zc, force_copy; 87 struct netdev_bpf bpf; 88 int err = 0; 89 90 force_zc = flags & XDP_ZEROCOPY; 91 force_copy = flags & XDP_COPY; 92 93 if (force_zc && force_copy) 94 return -EINVAL; 95 96 rtnl_lock(); 97 if (xdp_get_umem_from_qid(dev, queue_id)) { 98 err = -EBUSY; 99 goto out_rtnl_unlock; 100 } 101 102 err = xdp_reg_umem_at_qid(dev, umem, queue_id); 103 if (err) 104 goto out_rtnl_unlock; 105 106 umem->dev = dev; 107 umem->queue_id = queue_id; 108 109 dev_hold(dev); 110 111 if (force_copy) 112 /* For copy-mode, we are done. */ 113 goto out_rtnl_unlock; 114 115 if (!dev->netdev_ops->ndo_bpf || 116 !dev->netdev_ops->ndo_xsk_async_xmit) { 117 err = -EOPNOTSUPP; 118 goto err_unreg_umem; 119 } 120 121 bpf.command = XDP_SETUP_XSK_UMEM; 122 bpf.xsk.umem = umem; 123 bpf.xsk.queue_id = queue_id; 124 125 err = dev->netdev_ops->ndo_bpf(dev, &bpf); 126 if (err) 127 goto err_unreg_umem; 128 rtnl_unlock(); 129 130 umem->zc = true; 131 return 0; 132 133 err_unreg_umem: 134 if (!force_zc) 135 err = 0; /* fallback to copy mode */ 136 if (err) 137 xdp_clear_umem_at_qid(dev, queue_id); 138 out_rtnl_unlock: 139 rtnl_unlock(); 140 return err; 141 } 142 143 void xdp_umem_clear_dev(struct xdp_umem *umem) 144 { 145 struct netdev_bpf bpf; 146 int err; 147 148 ASSERT_RTNL(); 149 150 if (!umem->dev) 151 return; 152 153 if (umem->zc) { 154 bpf.command = XDP_SETUP_XSK_UMEM; 155 bpf.xsk.umem = NULL; 156 bpf.xsk.queue_id = umem->queue_id; 157 158 err = umem->dev->netdev_ops->ndo_bpf(umem->dev, &bpf); 159 160 if (err) 161 WARN(1, "failed to disable umem!\n"); 162 } 163 164 xdp_clear_umem_at_qid(umem->dev, umem->queue_id); 165 166 dev_put(umem->dev); 167 umem->dev = NULL; 168 umem->zc = false; 169 } 170 171 static void xdp_umem_unpin_pages(struct xdp_umem *umem) 172 { 173 unsigned int i; 174 175 for (i = 0; i < umem->npgs; i++) { 176 struct page *page = umem->pgs[i]; 177 178 set_page_dirty_lock(page); 179 put_page(page); 180 } 181 182 kfree(umem->pgs); 183 umem->pgs = NULL; 184 } 185 186 static void xdp_umem_unaccount_pages(struct xdp_umem *umem) 187 { 188 if (umem->user) { 189 atomic_long_sub(umem->npgs, &umem->user->locked_vm); 190 free_uid(umem->user); 191 } 192 } 193 194 static void xdp_umem_release(struct xdp_umem *umem) 195 { 196 rtnl_lock(); 197 xdp_umem_clear_dev(umem); 198 rtnl_unlock(); 199 200 ida_simple_remove(&umem_ida, umem->id); 201 202 if (umem->fq) { 203 xskq_destroy(umem->fq); 204 umem->fq = NULL; 205 } 206 207 if (umem->cq) { 208 xskq_destroy(umem->cq); 209 umem->cq = NULL; 210 } 211 212 xsk_reuseq_destroy(umem); 213 214 xdp_umem_unpin_pages(umem); 215 216 kfree(umem->pages); 217 umem->pages = NULL; 218 219 xdp_umem_unaccount_pages(umem); 220 kfree(umem); 221 } 222 223 static void xdp_umem_release_deferred(struct work_struct *work) 224 { 225 struct xdp_umem *umem = container_of(work, struct xdp_umem, work); 226 227 xdp_umem_release(umem); 228 } 229 230 void xdp_get_umem(struct xdp_umem *umem) 231 { 232 refcount_inc(&umem->users); 233 } 234 235 void xdp_put_umem(struct xdp_umem *umem) 236 { 237 if (!umem) 238 return; 239 240 if (refcount_dec_and_test(&umem->users)) { 241 INIT_WORK(&umem->work, xdp_umem_release_deferred); 242 schedule_work(&umem->work); 243 } 244 } 245 246 static int xdp_umem_pin_pages(struct xdp_umem *umem) 247 { 248 unsigned int gup_flags = FOLL_WRITE; 249 long npgs; 250 int err; 251 252 umem->pgs = kcalloc(umem->npgs, sizeof(*umem->pgs), 253 GFP_KERNEL | __GFP_NOWARN); 254 if (!umem->pgs) 255 return -ENOMEM; 256 257 down_read(¤t->mm->mmap_sem); 258 npgs = get_user_pages(umem->address, umem->npgs, 259 gup_flags | FOLL_LONGTERM, &umem->pgs[0], NULL); 260 up_read(¤t->mm->mmap_sem); 261 262 if (npgs != umem->npgs) { 263 if (npgs >= 0) { 264 umem->npgs = npgs; 265 err = -ENOMEM; 266 goto out_pin; 267 } 268 err = npgs; 269 goto out_pgs; 270 } 271 return 0; 272 273 out_pin: 274 xdp_umem_unpin_pages(umem); 275 out_pgs: 276 kfree(umem->pgs); 277 umem->pgs = NULL; 278 return err; 279 } 280 281 static int xdp_umem_account_pages(struct xdp_umem *umem) 282 { 283 unsigned long lock_limit, new_npgs, old_npgs; 284 285 if (capable(CAP_IPC_LOCK)) 286 return 0; 287 288 lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; 289 umem->user = get_uid(current_user()); 290 291 do { 292 old_npgs = atomic_long_read(&umem->user->locked_vm); 293 new_npgs = old_npgs + umem->npgs; 294 if (new_npgs > lock_limit) { 295 free_uid(umem->user); 296 umem->user = NULL; 297 return -ENOBUFS; 298 } 299 } while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs, 300 new_npgs) != old_npgs); 301 return 0; 302 } 303 304 static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) 305 { 306 u32 chunk_size = mr->chunk_size, headroom = mr->headroom; 307 unsigned int chunks, chunks_per_page; 308 u64 addr = mr->addr, size = mr->len; 309 int size_chk, err, i; 310 311 if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) { 312 /* Strictly speaking we could support this, if: 313 * - huge pages, or* 314 * - using an IOMMU, or 315 * - making sure the memory area is consecutive 316 * but for now, we simply say "computer says no". 317 */ 318 return -EINVAL; 319 } 320 321 if (!is_power_of_2(chunk_size)) 322 return -EINVAL; 323 324 if (!PAGE_ALIGNED(addr)) { 325 /* Memory area has to be page size aligned. For 326 * simplicity, this might change. 327 */ 328 return -EINVAL; 329 } 330 331 if ((addr + size) < addr) 332 return -EINVAL; 333 334 chunks = (unsigned int)div_u64(size, chunk_size); 335 if (chunks == 0) 336 return -EINVAL; 337 338 chunks_per_page = PAGE_SIZE / chunk_size; 339 if (chunks < chunks_per_page || chunks % chunks_per_page) 340 return -EINVAL; 341 342 headroom = ALIGN(headroom, 64); 343 344 size_chk = chunk_size - headroom - XDP_PACKET_HEADROOM; 345 if (size_chk < 0) 346 return -EINVAL; 347 348 umem->address = (unsigned long)addr; 349 umem->chunk_mask = ~((u64)chunk_size - 1); 350 umem->size = size; 351 umem->headroom = headroom; 352 umem->chunk_size_nohr = chunk_size - headroom; 353 umem->npgs = size / PAGE_SIZE; 354 umem->pgs = NULL; 355 umem->user = NULL; 356 INIT_LIST_HEAD(&umem->xsk_list); 357 spin_lock_init(&umem->xsk_list_lock); 358 359 refcount_set(&umem->users, 1); 360 361 err = xdp_umem_account_pages(umem); 362 if (err) 363 return err; 364 365 err = xdp_umem_pin_pages(umem); 366 if (err) 367 goto out_account; 368 369 umem->pages = kcalloc(umem->npgs, sizeof(*umem->pages), GFP_KERNEL); 370 if (!umem->pages) { 371 err = -ENOMEM; 372 goto out_account; 373 } 374 375 for (i = 0; i < umem->npgs; i++) 376 umem->pages[i].addr = page_address(umem->pgs[i]); 377 378 return 0; 379 380 out_account: 381 xdp_umem_unaccount_pages(umem); 382 return err; 383 } 384 385 struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr) 386 { 387 struct xdp_umem *umem; 388 int err; 389 390 umem = kzalloc(sizeof(*umem), GFP_KERNEL); 391 if (!umem) 392 return ERR_PTR(-ENOMEM); 393 394 err = ida_simple_get(&umem_ida, 0, 0, GFP_KERNEL); 395 if (err < 0) { 396 kfree(umem); 397 return ERR_PTR(err); 398 } 399 umem->id = err; 400 401 err = xdp_umem_reg(umem, mr); 402 if (err) { 403 ida_simple_remove(&umem_ida, umem->id); 404 kfree(umem); 405 return ERR_PTR(err); 406 } 407 408 return umem; 409 } 410 411 bool xdp_umem_validate_queues(struct xdp_umem *umem) 412 { 413 return umem->fq && umem->cq; 414 } 415