drivers/net/xen-netback/rx.c

   1 /*
   2  * Copyright (c) 2016 Citrix Systems Inc.
   3  * Copyright (c) 2002-2005, K A Fraser
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License version 2
   7  * as published by the Free Software Foundation; or, when distributed
   8  * separately from the Linux kernel or incorporated into other
   9  * software packages, subject to the following license:
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a copy
  12  * of this source file (the "Software"), to deal in the Software without
  13  * restriction, including without limitation the rights to use, copy, modify,
  14  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  15  * and to permit persons to whom the Software is furnished to do so, subject to
  16  * the following conditions:
  17  *
  18  * The above copyright notice and this permission notice shall be included in
  19  * all copies or substantial portions of the Software.
  20  *
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  26  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  27  * IN THE SOFTWARE.
  28  */
  29 #include "common.h"
  30
  31 #include <linux/kthread.h>
  32
  33 #include <xen/xen.h>
  34 #include <xen/events.h>
  35
  36 static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue)
  37 {
  38         RING_IDX prod, cons;
  39         struct sk_buff *skb;
  40         int needed;
  41
  42         skb = skb_peek(&queue->rx_queue);
  43         if (!skb)
  44                 return false;
  45
  46         needed = DIV_ROUND_UP(skb->len, XEN_PAGE_SIZE);
  47         if (skb_is_gso(skb))
  48                 needed++;
  49         if (skb->sw_hash)
  50                 needed++;
  51
  52         do {
  53                 prod = queue->rx.sring->req_prod;
  54                 cons = queue->rx.req_cons;
  55
  56                 if (prod - cons >= needed)
  57                         return true;
  58
  59                 queue->rx.sring->req_event = prod + 1;
  60
  61                 /* Make sure event is visible before we check prod
  62                  * again.
  63                  */
  64                 mb();
  65         } while (queue->rx.sring->req_prod != prod);
  66
  67         return false;
  68 }
  69
  70 void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb)
  71 {
  72         unsigned long flags;
  73
  74         spin_lock_irqsave(&queue->rx_queue.lock, flags);
  75
  76         __skb_queue_tail(&queue->rx_queue, skb);
  77
  78         queue->rx_queue_len += skb->len;
  79         if (queue->rx_queue_len > queue->rx_queue_max) {
  80                 struct net_device *dev = queue->vif->dev;
  81
  82                 netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id));
  83         }
  84
  85         spin_unlock_irqrestore(&queue->rx_queue.lock, flags);
  86 }
  87
  88 static struct sk_buff *xenvif_rx_dequeue(struct xenvif_queue *queue)
  89 {
  90         struct sk_buff *skb;
  91
  92         spin_lock_irq(&queue->rx_queue.lock);
  93
  94         skb = __skb_dequeue(&queue->rx_queue);
  95         if (skb) {
  96                 queue->rx_queue_len -= skb->len;
  97                 if (queue->rx_queue_len < queue->rx_queue_max) {
  98                         struct netdev_queue *txq;
  99
 100                         txq = netdev_get_tx_queue(queue->vif->dev, queue->id);
 101                         netif_tx_wake_queue(txq);
 102                 }
 103         }
 104
 105         spin_unlock_irq(&queue->rx_queue.lock);
 106
 107         return skb;
 108 }
 109
 110 static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
 111 {
 112         struct sk_buff *skb;
 113
 114         while ((skb = xenvif_rx_dequeue(queue)) != NULL)
 115                 kfree_skb(skb);
 116 }
 117
 118 static void xenvif_rx_queue_drop_expired(struct xenvif_queue *queue)
 119 {
 120         struct sk_buff *skb;
 121
 122         for (;;) {
 123                 skb = skb_peek(&queue->rx_queue);
 124                 if (!skb)
 125                         break;
 126                 if (time_before(jiffies, XENVIF_RX_CB(skb)->expires))
 127                         break;
 128                 xenvif_rx_dequeue(queue);
 129                 kfree_skb(skb);
 130         }
 131 }
 132
 133 static void xenvif_rx_copy_flush(struct xenvif_queue *queue)
 134 {
 135         unsigned int i;
 136         int notify;
 137
 138         gnttab_batch_copy(queue->rx_copy.op, queue->rx_copy.num);
 139
 140         for (i = 0; i < queue->rx_copy.num; i++) {
 141                 struct gnttab_copy *op;
 142
 143                 op = &queue->rx_copy.op[i];
 144
 145                 /* If the copy failed, overwrite the status field in
 146                  * the corresponding response.
 147                  */
 148                 if (unlikely(op->status != GNTST_okay)) {
 149                         struct xen_netif_rx_response *rsp;
 150
 151                         rsp = RING_GET_RESPONSE(&queue->rx,
 152                                                 queue->rx_copy.idx[i]);
 153                         rsp->status = op->status;
 154                 }
 155         }
 156
 157         queue->rx_copy.num = 0;
 158
 159         /* Push responses for all completed packets. */
 160         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->rx, notify);
 161         if (notify)
 162                 notify_remote_via_irq(queue->rx_irq);
 163
 164         __skb_queue_purge(queue->rx_copy.completed);
 165 }
 166
 167 static void xenvif_rx_copy_add(struct xenvif_queue *queue,
 168                                struct xen_netif_rx_request *req,
 169                                unsigned int offset, void *data, size_t len)
 170 {
 171         struct gnttab_copy *op;
 172         struct page *page;
 173         struct xen_page_foreign *foreign;
 174
 175         if (queue->rx_copy.num == COPY_BATCH_SIZE)
 176                 xenvif_rx_copy_flush(queue);
 177
 178         op = &queue->rx_copy.op[queue->rx_copy.num];
 179
 180         page = virt_to_page(data);
 181
 182         op->flags = GNTCOPY_dest_gref;
 183
 184         foreign = xen_page_foreign(page);
 185         if (foreign) {
 186                 op->source.domid = foreign->domid;
 187                 op->source.u.ref = foreign->gref;
 188                 op->flags |= GNTCOPY_source_gref;
 189         } else {
 190                 op->source.u.gmfn = virt_to_gfn(data);
 191                 op->source.domid  = DOMID_SELF;
 192         }
 193
 194         op->source.offset = xen_offset_in_page(data);
 195         op->dest.u.ref    = req->gref;
 196         op->dest.domid    = queue->vif->domid;
 197         op->dest.offset   = offset;
 198         op->len           = len;
 199
 200         queue->rx_copy.idx[queue->rx_copy.num] = queue->rx.req_cons;
 201         queue->rx_copy.num++;
 202 }
 203
 204 static unsigned int xenvif_gso_type(struct sk_buff *skb)
 205 {
 206         if (skb_is_gso(skb)) {
 207                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
 208                         return XEN_NETIF_GSO_TYPE_TCPV4;
 209                 else
 210                         return XEN_NETIF_GSO_TYPE_TCPV6;
 211         }
 212         return XEN_NETIF_GSO_TYPE_NONE;
 213 }
 214
 215 struct xenvif_pkt_state {
 216         struct sk_buff *skb;
 217         size_t remaining_len;
 218         struct sk_buff *frag_iter;
 219         int frag; /* frag == -1 => frag_iter->head */
 220         unsigned int frag_offset;
 221         struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX - 1];
 222         unsigned int extra_count;
 223         unsigned int slot;
 224 };
 225
 226 static void xenvif_rx_next_skb(struct xenvif_queue *queue,
 227                                struct xenvif_pkt_state *pkt)
 228 {
 229         struct sk_buff *skb;
 230         unsigned int gso_type;
 231
 232         skb = xenvif_rx_dequeue(queue);
 233
 234         queue->stats.tx_bytes += skb->len;
 235         queue->stats.tx_packets++;
 236
 237         /* Reset packet state. */
 238         memset(pkt, 0, sizeof(struct xenvif_pkt_state));
 239
 240         pkt->skb = skb;
 241         pkt->frag_iter = skb;
 242         pkt->remaining_len = skb->len;
 243         pkt->frag = -1;
 244
 245         gso_type = xenvif_gso_type(skb);
 246         if ((1 << gso_type) & queue->vif->gso_mask) {
 247                 struct xen_netif_extra_info *extra;
 248
 249                 extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
 250
 251                 extra->u.gso.type = gso_type;
 252                 extra->u.gso.size = skb_shinfo(skb)->gso_size;
 253                 extra->u.gso.pad = 0;
 254                 extra->u.gso.features = 0;
 255                 extra->type = XEN_NETIF_EXTRA_TYPE_GSO;
 256                 extra->flags = 0;
 257
 258                 pkt->extra_count++;
 259         }
 260
 261         if (skb->sw_hash) {
 262                 struct xen_netif_extra_info *extra;
 263
 264                 extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_HASH - 1];
 265
 266                 extra->u.hash.algorithm =
 267                         XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ;
 268
 269                 if (skb->l4_hash)
 270                         extra->u.hash.type =
 271                                 skb->protocol == htons(ETH_P_IP) ?
 272                                 _XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP :
 273                                 _XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP;
 274                 else
 275                         extra->u.hash.type =
 276                                 skb->protocol == htons(ETH_P_IP) ?
 277                                 _XEN_NETIF_CTRL_HASH_TYPE_IPV4 :
 278                                 _XEN_NETIF_CTRL_HASH_TYPE_IPV6;
 279
 280                 *(uint32_t *)extra->u.hash.value = skb_get_hash_raw(skb);
 281
 282                 extra->type = XEN_NETIF_EXTRA_TYPE_HASH;
 283                 extra->flags = 0;
 284
 285                 pkt->extra_count++;
 286         }
 287 }
 288
 289 static void xenvif_rx_complete(struct xenvif_queue *queue,
 290                                struct xenvif_pkt_state *pkt)
 291 {
 292         /* All responses are ready to be pushed. */
 293         queue->rx.rsp_prod_pvt = queue->rx.req_cons;
 294
 295         __skb_queue_tail(queue->rx_copy.completed, pkt->skb);
 296 }
 297
 298 static void xenvif_rx_next_frag(struct xenvif_pkt_state *pkt)
 299 {
 300         struct sk_buff *frag_iter = pkt->frag_iter;
 301         unsigned int nr_frags = skb_shinfo(frag_iter)->nr_frags;
 302
 303         pkt->frag++;
 304         pkt->frag_offset = 0;
 305
 306         if (pkt->frag >= nr_frags) {
 307                 if (frag_iter == pkt->skb)
 308                         pkt->frag_iter = skb_shinfo(frag_iter)->frag_list;
 309                 else
 310                         pkt->frag_iter = frag_iter->next;
 311
 312                 pkt->frag = -1;
 313         }
 314 }
 315
 316 static void xenvif_rx_next_chunk(struct xenvif_queue *queue,
 317                                  struct xenvif_pkt_state *pkt,
 318                                  unsigned int offset, void **data,
 319                                  size_t *len)
 320 {
 321         struct sk_buff *frag_iter = pkt->frag_iter;
 322         void *frag_data;
 323         size_t frag_len, chunk_len;
 324
 325         BUG_ON(!frag_iter);
 326
 327         if (pkt->frag == -1) {
 328                 frag_data = frag_iter->data;
 329                 frag_len = skb_headlen(frag_iter);
 330         } else {
 331                 skb_frag_t *frag = &skb_shinfo(frag_iter)->frags[pkt->frag];
 332
 333                 frag_data = skb_frag_address(frag);
 334                 frag_len = skb_frag_size(frag);
 335         }
 336
 337         frag_data += pkt->frag_offset;
 338         frag_len -= pkt->frag_offset;
 339
 340         chunk_len = min_t(size_t, frag_len, XEN_PAGE_SIZE - offset);
 341         chunk_len = min_t(size_t, chunk_len, XEN_PAGE_SIZE -
 342                                              xen_offset_in_page(frag_data));
 343
 344         pkt->frag_offset += chunk_len;
 345
 346         /* Advance to next frag? */
 347         if (frag_len == chunk_len)
 348                 xenvif_rx_next_frag(pkt);
 349
 350         *data = frag_data;
 351         *len = chunk_len;
 352 }
 353
 354 static void xenvif_rx_data_slot(struct xenvif_queue *queue,
 355                                 struct xenvif_pkt_state *pkt,
 356                                 struct xen_netif_rx_request *req,
 357                                 struct xen_netif_rx_response *rsp)
 358 {
 359         unsigned int offset = 0;
 360         unsigned int flags;
 361
 362         do {
 363                 size_t len;
 364                 void *data;
 365
 366                 xenvif_rx_next_chunk(queue, pkt, offset, &data, &len);
 367                 xenvif_rx_copy_add(queue, req, offset, data, len);
 368
 369                 offset += len;
 370                 pkt->remaining_len -= len;
 371
 372         } while (offset < XEN_PAGE_SIZE && pkt->remaining_len > 0);
 373
 374         if (pkt->remaining_len > 0)
 375                 flags = XEN_NETRXF_more_data;
 376         else
 377                 flags = 0;
 378
 379         if (pkt->slot == 0) {
 380                 struct sk_buff *skb = pkt->skb;
 381
 382                 if (skb->ip_summed == CHECKSUM_PARTIAL)
 383                         flags |= XEN_NETRXF_csum_blank |
 384                                  XEN_NETRXF_data_validated;
 385                 else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
 386                         flags |= XEN_NETRXF_data_validated;
 387
 388                 if (pkt->extra_count != 0)
 389                         flags |= XEN_NETRXF_extra_info;
 390         }
 391
 392         rsp->offset = 0;
 393         rsp->flags = flags;
 394         rsp->id = req->id;
 395         rsp->status = (s16)offset;
 396 }
 397
 398 static void xenvif_rx_extra_slot(struct xenvif_queue *queue,
 399                                  struct xenvif_pkt_state *pkt,
 400                                  struct xen_netif_rx_request *req,
 401                                  struct xen_netif_rx_response *rsp)
 402 {
 403         struct xen_netif_extra_info *extra = (void *)rsp;
 404         unsigned int i;
 405
 406         pkt->extra_count--;
 407
 408         for (i = 0; i < ARRAY_SIZE(pkt->extras); i++) {
 409                 if (pkt->extras[i].type) {
 410                         *extra = pkt->extras[i];
 411
 412                         if (pkt->extra_count != 0)
 413                                 extra->flags |= XEN_NETIF_EXTRA_FLAG_MORE;
 414
 415                         pkt->extras[i].type = 0;
 416                         return;
 417                 }
 418         }
 419         BUG();
 420 }
 421
 422 static void xenvif_rx_skb(struct xenvif_queue *queue)
 423 {
 424         struct xenvif_pkt_state pkt;
 425
 426         xenvif_rx_next_skb(queue, &pkt);
 427
 428         queue->last_rx_time = jiffies;
 429
 430         do {
 431                 struct xen_netif_rx_request *req;
 432                 struct xen_netif_rx_response *rsp;
 433
 434                 req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons);
 435                 rsp = RING_GET_RESPONSE(&queue->rx, queue->rx.req_cons);
 436
 437                 /* Extras must go after the first data slot */
 438                 if (pkt.slot != 0 && pkt.extra_count != 0)
 439                         xenvif_rx_extra_slot(queue, &pkt, req, rsp);
 440                 else
 441                         xenvif_rx_data_slot(queue, &pkt, req, rsp);
 442
 443                 queue->rx.req_cons++;
 444                 pkt.slot++;
 445         } while (pkt.remaining_len > 0 || pkt.extra_count != 0);
 446
 447         xenvif_rx_complete(queue, &pkt);
 448 }
 449
 450 #define RX_BATCH_SIZE 64
 451
 452 void xenvif_rx_action(struct xenvif_queue *queue)
 453 {
 454         struct sk_buff_head completed_skbs;
 455         unsigned int work_done = 0;
 456
 457         __skb_queue_head_init(&completed_skbs);
 458         queue->rx_copy.completed = &completed_skbs;
 459
 460         while (xenvif_rx_ring_slots_available(queue) &&
 461                work_done < RX_BATCH_SIZE) {
 462                 xenvif_rx_skb(queue);
 463                 work_done++;
 464         }
 465
 466         /* Flush any pending copies and complete all skbs. */
 467         xenvif_rx_copy_flush(queue);
 468 }
 469
 470 static bool xenvif_rx_queue_stalled(struct xenvif_queue *queue)
 471 {
 472         RING_IDX prod, cons;
 473
 474         prod = queue->rx.sring->req_prod;
 475         cons = queue->rx.req_cons;
 476
 477         return !queue->stalled &&
 478                 prod - cons < 1 &&
 479                 time_after(jiffies,
 480                            queue->last_rx_time + queue->vif->stall_timeout);
 481 }
 482
 483 static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
 484 {
 485         RING_IDX prod, cons;
 486
 487         prod = queue->rx.sring->req_prod;
 488         cons = queue->rx.req_cons;
 489
 490         return queue->stalled && prod - cons >= 1;
 491 }
 492
 493 static bool xenvif_have_rx_work(struct xenvif_queue *queue)
 494 {
 495         return xenvif_rx_ring_slots_available(queue) ||
 496                 (queue->vif->stall_timeout &&
 497                  (xenvif_rx_queue_stalled(queue) ||
 498                   xenvif_rx_queue_ready(queue))) ||
 499                 kthread_should_stop() ||
 500                 queue->vif->disabled;
 501 }
 502
 503 static long xenvif_rx_queue_timeout(struct xenvif_queue *queue)
 504 {
 505         struct sk_buff *skb;
 506         long timeout;
 507
 508         skb = skb_peek(&queue->rx_queue);
 509         if (!skb)
 510                 return MAX_SCHEDULE_TIMEOUT;
 511
 512         timeout = XENVIF_RX_CB(skb)->expires - jiffies;
 513         return timeout < 0 ? 0 : timeout;
 514 }
 515
 516 /* Wait until the guest Rx thread has work.
 517  *
 518  * The timeout needs to be adjusted based on the current head of the
 519  * queue (and not just the head at the beginning).  In particular, if
 520  * the queue is initially empty an infinite timeout is used and this
 521  * needs to be reduced when a skb is queued.
 522  *
 523  * This cannot be done with wait_event_timeout() because it only
 524  * calculates the timeout once.
 525  */
 526 static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
 527 {
 528         DEFINE_WAIT(wait);
 529
 530         if (xenvif_have_rx_work(queue))
 531                 return;
 532
 533         for (;;) {
 534                 long ret;
 535
 536                 prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
 537                 if (xenvif_have_rx_work(queue))
 538                         break;
 539                 ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
 540                 if (!ret)
 541                         break;
 542         }
 543         finish_wait(&queue->wq, &wait);
 544 }
 545
 546 static void xenvif_queue_carrier_off(struct xenvif_queue *queue)
 547 {
 548         struct xenvif *vif = queue->vif;
 549
 550         queue->stalled = true;
 551
 552         /* At least one queue has stalled? Disable the carrier. */
 553         spin_lock(&vif->lock);
 554         if (vif->stalled_queues++ == 0) {
 555                 netdev_info(vif->dev, "Guest Rx stalled");
 556                 netif_carrier_off(vif->dev);
 557         }
 558         spin_unlock(&vif->lock);
 559 }
 560
 561 static void xenvif_queue_carrier_on(struct xenvif_queue *queue)
 562 {
 563         struct xenvif *vif = queue->vif;
 564
 565         queue->last_rx_time = jiffies; /* Reset Rx stall detection. */
 566         queue->stalled = false;
 567
 568         /* All queues are ready? Enable the carrier. */
 569         spin_lock(&vif->lock);
 570         if (--vif->stalled_queues == 0) {
 571                 netdev_info(vif->dev, "Guest Rx ready");
 572                 netif_carrier_on(vif->dev);
 573         }
 574         spin_unlock(&vif->lock);
 575 }
 576
 577 int xenvif_kthread_guest_rx(void *data)
 578 {
 579         struct xenvif_queue *queue = data;
 580         struct xenvif *vif = queue->vif;
 581
 582         if (!vif->stall_timeout)
 583                 xenvif_queue_carrier_on(queue);
 584
 585         for (;;) {
 586                 xenvif_wait_for_rx_work(queue);
 587
 588                 if (kthread_should_stop())
 589                         break;
 590
 591                 /* This frontend is found to be rogue, disable it in
 592                  * kthread context. Currently this is only set when
 593                  * netback finds out frontend sends malformed packet,
 594                  * but we cannot disable the interface in softirq
 595                  * context so we defer it here, if this thread is
 596                  * associated with queue 0.
 597                  */
 598                 if (unlikely(vif->disabled && queue->id == 0)) {
 599                         xenvif_carrier_off(vif);
 600                         break;
 601                 }
 602
 603                 if (!skb_queue_empty(&queue->rx_queue))
 604                         xenvif_rx_action(queue);
 605
 606                 /* If the guest hasn't provided any Rx slots for a
 607                  * while it's probably not responsive, drop the
 608                  * carrier so packets are dropped earlier.
 609                  */
 610                 if (vif->stall_timeout) {
 611                         if (xenvif_rx_queue_stalled(queue))
 612                                 xenvif_queue_carrier_off(queue);
 613                         else if (xenvif_rx_queue_ready(queue))
 614                                 xenvif_queue_carrier_on(queue);
 615                 }
 616
 617                 /* Queued packets may have foreign pages from other
 618                  * domains.  These cannot be queued indefinitely as
 619                  * this would starve guests of grant refs and transmit
 620                  * slots.
 621                  */
 622                 xenvif_rx_queue_drop_expired(queue);
 623
 624                 cond_resched();
 625         }
 626
 627         /* Bin any remaining skbs */
 628         xenvif_rx_queue_purge(queue);
 629
 630         return 0;
 631 }