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