net/xdp/xdp_umem.c

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