drivers/net/xen-netback/netback.c

   1 /*
   2  * Back-end of the driver for virtual network devices. This portion of the
   3  * driver exports a 'unified' network-device interface that can be accessed
   4  * by any operating system that implements a compatible front end. A
   5  * reference front-end implementation can be found in:
   6  *  drivers/net/xen-netfront.c
   7  *
   8  * Copyright (c) 2002-2005, K A Fraser
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License version 2
  12  * as published by the Free Software Foundation; or, when distributed
  13  * separately from the Linux kernel or incorporated into other
  14  * software packages, subject to the following license:
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a copy
  17  * of this source file (the "Software"), to deal in the Software without
  18  * restriction, including without limitation the rights to use, copy, modify,
  19  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  20  * and to permit persons to whom the Software is furnished to do so, subject to
  21  * the following conditions:
  22  *
  23  * The above copyright notice and this permission notice shall be included in
  24  * all copies or substantial portions of the Software.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  27  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  28  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  29  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  30  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  31  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  32  * IN THE SOFTWARE.
  33  */
  34
  35 #include "common.h"
  36
  37 #include <linux/kthread.h>
  38 #include <linux/if_vlan.h>
  39 #include <linux/udp.h>
  40 #include <linux/highmem.h>
  41
  42 #include <net/tcp.h>
  43
  44 #include <xen/xen.h>
  45 #include <xen/events.h>
  46 #include <xen/interface/memory.h>
  47 #include <xen/page.h>
  48
  49 #include <asm/xen/hypercall.h>
  50
  51 /* Provide an option to disable split event channels at load time as
  52  * event channels are limited resource. Split event channels are
  53  * enabled by default.
  54  */
  55 bool separate_tx_rx_irq = true;
  56 module_param(separate_tx_rx_irq, bool, 0644);
  57
  58 /* The time that packets can stay on the guest Rx internal queue
  59  * before they are dropped.
  60  */
  61 unsigned int rx_drain_timeout_msecs = 10000;
  62 module_param(rx_drain_timeout_msecs, uint, 0444);
  63
  64 /* The length of time before the frontend is considered unresponsive
  65  * because it isn't providing Rx slots.
  66  */
  67 unsigned int rx_stall_timeout_msecs = 60000;
  68 module_param(rx_stall_timeout_msecs, uint, 0444);
  69
  70 unsigned int xenvif_max_queues;
  71 module_param_named(max_queues, xenvif_max_queues, uint, 0644);
  72 MODULE_PARM_DESC(max_queues,
  73                  "Maximum number of queues per virtual interface");
  74
  75 /*
  76  * This is the maximum slots a skb can have. If a guest sends a skb
  77  * which exceeds this limit it is considered malicious.
  78  */
  79 #define FATAL_SKB_SLOTS_DEFAULT 20
  80 static unsigned int fatal_skb_slots = FATAL_SKB_SLOTS_DEFAULT;
  81 module_param(fatal_skb_slots, uint, 0444);
  82
  83 /* The amount to copy out of the first guest Tx slot into the skb's
  84  * linear area.  If the first slot has more data, it will be mapped
  85  * and put into the first frag.
  86  *
  87  * This is sized to avoid pulling headers from the frags for most
  88  * TCP/IP packets.
  89  */
  90 #define XEN_NETBACK_TX_COPY_LEN 128
  91
  92
  93 static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
  94                                u8 status);
  95
  96 static void make_tx_response(struct xenvif_queue *queue,
  97                              struct xen_netif_tx_request *txp,
  98                              s8       st);
  99 static void push_tx_responses(struct xenvif_queue *queue);
 100
 101 static inline int tx_work_todo(struct xenvif_queue *queue);
 102
 103 static struct xen_netif_rx_response *make_rx_response(struct xenvif_queue *queue,
 104                                              u16      id,
 105                                              s8       st,
 106                                              u16      offset,
 107                                              u16      size,
 108                                              u16      flags);
 109
 110 static inline unsigned long idx_to_pfn(struct xenvif_queue *queue,
 111                                        u16 idx)
 112 {
 113         return page_to_pfn(queue->mmap_pages[idx]);
 114 }
 115
 116 static inline unsigned long idx_to_kaddr(struct xenvif_queue *queue,
 117                                          u16 idx)
 118 {
 119         return (unsigned long)pfn_to_kaddr(idx_to_pfn(queue, idx));
 120 }
 121
 122 #define callback_param(vif, pending_idx) \
 123         (vif->pending_tx_info[pending_idx].callback_struct)
 124
 125 /* Find the containing VIF's structure from a pointer in pending_tx_info array
 126  */
 127 static inline struct xenvif_queue *ubuf_to_queue(const struct ubuf_info *ubuf)
 128 {
 129         u16 pending_idx = ubuf->desc;
 130         struct pending_tx_info *temp =
 131                 container_of(ubuf, struct pending_tx_info, callback_struct);
 132         return container_of(temp - pending_idx,
 133                             struct xenvif_queue,
 134                             pending_tx_info[0]);
 135 }
 136
 137 static u16 frag_get_pending_idx(skb_frag_t *frag)
 138 {
 139         return (u16)frag->page_offset;
 140 }
 141
 142 static void frag_set_pending_idx(skb_frag_t *frag, u16 pending_idx)
 143 {
 144         frag->page_offset = pending_idx;
 145 }
 146
 147 static inline pending_ring_idx_t pending_index(unsigned i)
 148 {
 149         return i & (MAX_PENDING_REQS-1);
 150 }
 151
 152 bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue, int needed)
 153 {
 154         RING_IDX prod, cons;
 155
 156         do {
 157                 prod = queue->rx.sring->req_prod;
 158                 cons = queue->rx.req_cons;
 159
 160                 if (prod - cons >= needed)
 161                         return true;
 162
 163                 queue->rx.sring->req_event = prod + 1;
 164
 165                 /* Make sure event is visible before we check prod
 166                  * again.
 167                  */
 168                 mb();
 169         } while (queue->rx.sring->req_prod != prod);
 170
 171         return false;
 172 }
 173
 174 void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb)
 175 {
 176         unsigned long flags;
 177
 178         spin_lock_irqsave(&queue->rx_queue.lock, flags);
 179
 180         __skb_queue_tail(&queue->rx_queue, skb);
 181
 182         queue->rx_queue_len += skb->len;
 183         if (queue->rx_queue_len > queue->rx_queue_max)
 184                 netif_tx_stop_queue(netdev_get_tx_queue(queue->vif->dev, queue->id));
 185
 186         spin_unlock_irqrestore(&queue->rx_queue.lock, flags);
 187 }
 188
 189 static struct sk_buff *xenvif_rx_dequeue(struct xenvif_queue *queue)
 190 {
 191         struct sk_buff *skb;
 192
 193         spin_lock_irq(&queue->rx_queue.lock);
 194
 195         skb = __skb_dequeue(&queue->rx_queue);
 196         if (skb)
 197                 queue->rx_queue_len -= skb->len;
 198
 199         spin_unlock_irq(&queue->rx_queue.lock);
 200
 201         return skb;
 202 }
 203
 204 static void xenvif_rx_queue_maybe_wake(struct xenvif_queue *queue)
 205 {
 206         spin_lock_irq(&queue->rx_queue.lock);
 207
 208         if (queue->rx_queue_len < queue->rx_queue_max)
 209                 netif_tx_wake_queue(netdev_get_tx_queue(queue->vif->dev, queue->id));
 210
 211         spin_unlock_irq(&queue->rx_queue.lock);
 212 }
 213
 214
 215 static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
 216 {
 217         struct sk_buff *skb;
 218         while ((skb = xenvif_rx_dequeue(queue)) != NULL)
 219                 kfree_skb(skb);
 220 }
 221
 222 static void xenvif_rx_queue_drop_expired(struct xenvif_queue *queue)
 223 {
 224         struct sk_buff *skb;
 225
 226         for(;;) {
 227                 skb = skb_peek(&queue->rx_queue);
 228                 if (!skb)
 229                         break;
 230                 if (time_before(jiffies, XENVIF_RX_CB(skb)->expires))
 231                         break;
 232                 xenvif_rx_dequeue(queue);
 233                 kfree_skb(skb);
 234         }
 235 }
 236
 237 struct netrx_pending_operations {
 238         unsigned copy_prod, copy_cons;
 239         unsigned meta_prod, meta_cons;
 240         struct gnttab_copy *copy;
 241         struct xenvif_rx_meta *meta;
 242         int copy_off;
 243         grant_ref_t copy_gref;
 244 };
 245
 246 static struct xenvif_rx_meta *get_next_rx_buffer(struct xenvif_queue *queue,
 247                                                  struct netrx_pending_operations *npo)
 248 {
 249         struct xenvif_rx_meta *meta;
 250         struct xen_netif_rx_request *req;
 251
 252         req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons++);
 253
 254         meta = npo->meta + npo->meta_prod++;
 255         meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
 256         meta->gso_size = 0;
 257         meta->size = 0;
 258         meta->id = req->id;
 259
 260         npo->copy_off = 0;
 261         npo->copy_gref = req->gref;
 262
 263         return meta;
 264 }
 265
 266 /*
 267  * Set up the grant operations for this fragment. If it's a flipping
 268  * interface, we also set up the unmap request from here.
 269  */
 270 static void xenvif_gop_frag_copy(struct xenvif_queue *queue, struct sk_buff *skb,
 271                                  struct netrx_pending_operations *npo,
 272                                  struct page *page, unsigned long size,
 273                                  unsigned long offset, int *head)
 274 {
 275         struct gnttab_copy *copy_gop;
 276         struct xenvif_rx_meta *meta;
 277         unsigned long bytes;
 278         int gso_type = XEN_NETIF_GSO_TYPE_NONE;
 279
 280         /* Data must not cross a page boundary. */
 281         BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
 282
 283         meta = npo->meta + npo->meta_prod - 1;
 284
 285         /* Skip unused frames from start of page */
 286         page += offset >> PAGE_SHIFT;
 287         offset &= ~PAGE_MASK;
 288
 289         while (size > 0) {
 290                 struct xen_page_foreign *foreign;
 291
 292                 BUG_ON(offset >= PAGE_SIZE);
 293                 BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
 294
 295                 if (npo->copy_off == MAX_BUFFER_OFFSET)
 296                         meta = get_next_rx_buffer(queue, npo);
 297
 298                 bytes = PAGE_SIZE - offset;
 299                 if (bytes > size)
 300                         bytes = size;
 301
 302                 if (npo->copy_off + bytes > MAX_BUFFER_OFFSET)
 303                         bytes = MAX_BUFFER_OFFSET - npo->copy_off;
 304
 305                 copy_gop = npo->copy + npo->copy_prod++;
 306                 copy_gop->flags = GNTCOPY_dest_gref;
 307                 copy_gop->len = bytes;
 308
 309                 foreign = xen_page_foreign(page);
 310                 if (foreign) {
 311                         copy_gop->source.domid = foreign->domid;
 312                         copy_gop->source.u.ref = foreign->gref;
 313                         copy_gop->flags |= GNTCOPY_source_gref;
 314                 } else {
 315                         copy_gop->source.domid = DOMID_SELF;
 316                         copy_gop->source.u.gmfn =
 317                                 virt_to_mfn(page_address(page));
 318                 }
 319                 copy_gop->source.offset = offset;
 320
 321                 copy_gop->dest.domid = queue->vif->domid;
 322                 copy_gop->dest.offset = npo->copy_off;
 323                 copy_gop->dest.u.ref = npo->copy_gref;
 324
 325                 npo->copy_off += bytes;
 326                 meta->size += bytes;
 327
 328                 offset += bytes;
 329                 size -= bytes;
 330
 331                 /* Next frame */
 332                 if (offset == PAGE_SIZE && size) {
 333                         BUG_ON(!PageCompound(page));
 334                         page++;
 335                         offset = 0;
 336                 }
 337
 338                 /* Leave a gap for the GSO descriptor. */
 339                 if (skb_is_gso(skb)) {
 340                         if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
 341                                 gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
 342                         else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
 343                                 gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
 344                 }
 345
 346                 if (*head && ((1 << gso_type) & queue->vif->gso_mask))
 347                         queue->rx.req_cons++;
 348
 349                 *head = 0; /* There must be something in this buffer now. */
 350
 351         }
 352 }
 353
 354 /*
 355  * Prepare an SKB to be transmitted to the frontend.
 356  *
 357  * This function is responsible for allocating grant operations, meta
 358  * structures, etc.
 359  *
 360  * It returns the number of meta structures consumed. The number of
 361  * ring slots used is always equal to the number of meta slots used
 362  * plus the number of GSO descriptors used. Currently, we use either
 363  * zero GSO descriptors (for non-GSO packets) or one descriptor (for
 364  * frontend-side LRO).
 365  */
 366 static int xenvif_gop_skb(struct sk_buff *skb,
 367                           struct netrx_pending_operations *npo,
 368                           struct xenvif_queue *queue)
 369 {
 370         struct xenvif *vif = netdev_priv(skb->dev);
 371         int nr_frags = skb_shinfo(skb)->nr_frags;
 372         int i;
 373         struct xen_netif_rx_request *req;
 374         struct xenvif_rx_meta *meta;
 375         unsigned char *data;
 376         int head = 1;
 377         int old_meta_prod;
 378         int gso_type;
 379
 380         old_meta_prod = npo->meta_prod;
 381
 382         gso_type = XEN_NETIF_GSO_TYPE_NONE;
 383         if (skb_is_gso(skb)) {
 384                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
 385                         gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
 386                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
 387                         gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
 388         }
 389
 390         /* Set up a GSO prefix descriptor, if necessary */
 391         if ((1 << gso_type) & vif->gso_prefix_mask) {
 392                 req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons++);
 393                 meta = npo->meta + npo->meta_prod++;
 394                 meta->gso_type = gso_type;
 395                 meta->gso_size = skb_shinfo(skb)->gso_size;
 396                 meta->size = 0;
 397                 meta->id = req->id;
 398         }
 399
 400         req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons++);
 401         meta = npo->meta + npo->meta_prod++;
 402
 403         if ((1 << gso_type) & vif->gso_mask) {
 404                 meta->gso_type = gso_type;
 405                 meta->gso_size = skb_shinfo(skb)->gso_size;
 406         } else {
 407                 meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
 408                 meta->gso_size = 0;
 409         }
 410
 411         meta->size = 0;
 412         meta->id = req->id;
 413         npo->copy_off = 0;
 414         npo->copy_gref = req->gref;
 415
 416         data = skb->data;
 417         while (data < skb_tail_pointer(skb)) {
 418                 unsigned int offset = offset_in_page(data);
 419                 unsigned int len = PAGE_SIZE - offset;
 420
 421                 if (data + len > skb_tail_pointer(skb))
 422                         len = skb_tail_pointer(skb) - data;
 423
 424                 xenvif_gop_frag_copy(queue, skb, npo,
 425                                      virt_to_page(data), len, offset, &head);
 426                 data += len;
 427         }
 428
 429         for (i = 0; i < nr_frags; i++) {
 430                 xenvif_gop_frag_copy(queue, skb, npo,
 431                                      skb_frag_page(&skb_shinfo(skb)->frags[i]),
 432                                      skb_frag_size(&skb_shinfo(skb)->frags[i]),
 433                                      skb_shinfo(skb)->frags[i].page_offset,
 434                                      &head);
 435         }
 436
 437         return npo->meta_prod - old_meta_prod;
 438 }
 439
 440 /*
 441  * This is a twin to xenvif_gop_skb.  Assume that xenvif_gop_skb was
 442  * used to set up the operations on the top of
 443  * netrx_pending_operations, which have since been done.  Check that
 444  * they didn't give any errors and advance over them.
 445  */
 446 static int xenvif_check_gop(struct xenvif *vif, int nr_meta_slots,
 447                             struct netrx_pending_operations *npo)
 448 {
 449         struct gnttab_copy     *copy_op;
 450         int status = XEN_NETIF_RSP_OKAY;
 451         int i;
 452
 453         for (i = 0; i < nr_meta_slots; i++) {
 454                 copy_op = npo->copy + npo->copy_cons++;
 455                 if (copy_op->status != GNTST_okay) {
 456                         netdev_dbg(vif->dev,
 457                                    "Bad status %d from copy to DOM%d.\n",
 458                                    copy_op->status, vif->domid);
 459                         status = XEN_NETIF_RSP_ERROR;
 460                 }
 461         }
 462
 463         return status;
 464 }
 465
 466 static void xenvif_add_frag_responses(struct xenvif_queue *queue, int status,
 467                                       struct xenvif_rx_meta *meta,
 468                                       int nr_meta_slots)
 469 {
 470         int i;
 471         unsigned long offset;
 472
 473         /* No fragments used */
 474         if (nr_meta_slots <= 1)
 475                 return;
 476
 477         nr_meta_slots--;
 478
 479         for (i = 0; i < nr_meta_slots; i++) {
 480                 int flags;
 481                 if (i == nr_meta_slots - 1)
 482                         flags = 0;
 483                 else
 484                         flags = XEN_NETRXF_more_data;
 485
 486                 offset = 0;
 487                 make_rx_response(queue, meta[i].id, status, offset,
 488                                  meta[i].size, flags);
 489         }
 490 }
 491
 492 void xenvif_kick_thread(struct xenvif_queue *queue)
 493 {
 494         wake_up(&queue->wq);
 495 }
 496
 497 static void xenvif_rx_action(struct xenvif_queue *queue)
 498 {
 499         s8 status;
 500         u16 flags;
 501         struct xen_netif_rx_response *resp;
 502         struct sk_buff_head rxq;
 503         struct sk_buff *skb;
 504         LIST_HEAD(notify);
 505         int ret;
 506         unsigned long offset;
 507         bool need_to_notify = false;
 508
 509         struct netrx_pending_operations npo = {
 510                 .copy  = queue->grant_copy_op,
 511                 .meta  = queue->meta,
 512         };
 513
 514         skb_queue_head_init(&rxq);
 515
 516         while (xenvif_rx_ring_slots_available(queue, XEN_NETBK_RX_SLOTS_MAX)
 517                && (skb = xenvif_rx_dequeue(queue)) != NULL) {
 518                 queue->last_rx_time = jiffies;
 519
 520                 XENVIF_RX_CB(skb)->meta_slots_used = xenvif_gop_skb(skb, &npo, queue);
 521
 522                 __skb_queue_tail(&rxq, skb);
 523         }
 524
 525         BUG_ON(npo.meta_prod > ARRAY_SIZE(queue->meta));
 526
 527         if (!npo.copy_prod)
 528                 goto done;
 529
 530         BUG_ON(npo.copy_prod > MAX_GRANT_COPY_OPS);
 531         gnttab_batch_copy(queue->grant_copy_op, npo.copy_prod);
 532
 533         while ((skb = __skb_dequeue(&rxq)) != NULL) {
 534
 535                 if ((1 << queue->meta[npo.meta_cons].gso_type) &
 536                     queue->vif->gso_prefix_mask) {
 537                         resp = RING_GET_RESPONSE(&queue->rx,
 538                                                  queue->rx.rsp_prod_pvt++);
 539
 540                         resp->flags = XEN_NETRXF_gso_prefix | XEN_NETRXF_more_data;
 541
 542                         resp->offset = queue->meta[npo.meta_cons].gso_size;
 543                         resp->id = queue->meta[npo.meta_cons].id;
 544                         resp->status = XENVIF_RX_CB(skb)->meta_slots_used;
 545
 546                         npo.meta_cons++;
 547                         XENVIF_RX_CB(skb)->meta_slots_used--;
 548                 }
 549
 550
 551                 queue->stats.tx_bytes += skb->len;
 552                 queue->stats.tx_packets++;
 553
 554                 status = xenvif_check_gop(queue->vif,
 555                                           XENVIF_RX_CB(skb)->meta_slots_used,
 556                                           &npo);
 557
 558                 if (XENVIF_RX_CB(skb)->meta_slots_used == 1)
 559                         flags = 0;
 560                 else
 561                         flags = XEN_NETRXF_more_data;
 562
 563                 if (skb->ip_summed == CHECKSUM_PARTIAL) /* local packet? */
 564                         flags |= XEN_NETRXF_csum_blank | XEN_NETRXF_data_validated;
 565                 else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
 566                         /* remote but checksummed. */
 567                         flags |= XEN_NETRXF_data_validated;
 568
 569                 offset = 0;
 570                 resp = make_rx_response(queue, queue->meta[npo.meta_cons].id,
 571                                         status, offset,
 572                                         queue->meta[npo.meta_cons].size,
 573                                         flags);
 574
 575                 if ((1 << queue->meta[npo.meta_cons].gso_type) &
 576                     queue->vif->gso_mask) {
 577                         struct xen_netif_extra_info *gso =
 578                                 (struct xen_netif_extra_info *)
 579                                 RING_GET_RESPONSE(&queue->rx,
 580                                                   queue->rx.rsp_prod_pvt++);
 581
 582                         resp->flags |= XEN_NETRXF_extra_info;
 583
 584                         gso->u.gso.type = queue->meta[npo.meta_cons].gso_type;
 585                         gso->u.gso.size = queue->meta[npo.meta_cons].gso_size;
 586                         gso->u.gso.pad = 0;
 587                         gso->u.gso.features = 0;
 588
 589                         gso->type = XEN_NETIF_EXTRA_TYPE_GSO;
 590                         gso->flags = 0;
 591                 }
 592
 593                 xenvif_add_frag_responses(queue, status,
 594                                           queue->meta + npo.meta_cons + 1,
 595                                           XENVIF_RX_CB(skb)->meta_slots_used);
 596
 597                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->rx, ret);
 598
 599                 need_to_notify |= !!ret;
 600
 601                 npo.meta_cons += XENVIF_RX_CB(skb)->meta_slots_used;
 602                 dev_kfree_skb(skb);
 603         }
 604
 605 done:
 606         if (need_to_notify)
 607                 notify_remote_via_irq(queue->rx_irq);
 608 }
 609
 610 void xenvif_napi_schedule_or_enable_events(struct xenvif_queue *queue)
 611 {
 612         int more_to_do;
 613
 614         RING_FINAL_CHECK_FOR_REQUESTS(&queue->tx, more_to_do);
 615
 616         if (more_to_do)
 617                 napi_schedule(&queue->napi);
 618 }
 619
 620 static void tx_add_credit(struct xenvif_queue *queue)
 621 {
 622         unsigned long max_burst, max_credit;
 623
 624         /*
 625          * Allow a burst big enough to transmit a jumbo packet of up to 128kB.
 626          * Otherwise the interface can seize up due to insufficient credit.
 627          */
 628         max_burst = RING_GET_REQUEST(&queue->tx, queue->tx.req_cons)->size;
 629         max_burst = min(max_burst, 131072UL);
 630         max_burst = max(max_burst, queue->credit_bytes);
 631
 632         /* Take care that adding a new chunk of credit doesn't wrap to zero. */
 633         max_credit = queue->remaining_credit + queue->credit_bytes;
 634         if (max_credit < queue->remaining_credit)
 635                 max_credit = ULONG_MAX; /* wrapped: clamp to ULONG_MAX */
 636
 637         queue->remaining_credit = min(max_credit, max_burst);
 638 }
 639
 640 void xenvif_tx_credit_callback(unsigned long data)
 641 {
 642         struct xenvif_queue *queue = (struct xenvif_queue *)data;
 643         tx_add_credit(queue);
 644         xenvif_napi_schedule_or_enable_events(queue);
 645 }
 646
 647 static void xenvif_tx_err(struct xenvif_queue *queue,
 648                           struct xen_netif_tx_request *txp, RING_IDX end)
 649 {
 650         RING_IDX cons = queue->tx.req_cons;
 651         unsigned long flags;
 652
 653         do {
 654                 spin_lock_irqsave(&queue->response_lock, flags);
 655                 make_tx_response(queue, txp, XEN_NETIF_RSP_ERROR);
 656                 push_tx_responses(queue);
 657                 spin_unlock_irqrestore(&queue->response_lock, flags);
 658                 if (cons == end)
 659                         break;
 660                 txp = RING_GET_REQUEST(&queue->tx, cons++);
 661         } while (1);
 662         queue->tx.req_cons = cons;
 663 }
 664
 665 static void xenvif_fatal_tx_err(struct xenvif *vif)
 666 {
 667         netdev_err(vif->dev, "fatal error; disabling device\n");
 668         vif->disabled = true;
 669         /* Disable the vif from queue 0's kthread */
 670         if (vif->queues)
 671                 xenvif_kick_thread(&vif->queues[0]);
 672 }
 673
 674 static int xenvif_count_requests(struct xenvif_queue *queue,
 675                                  struct xen_netif_tx_request *first,
 676                                  struct xen_netif_tx_request *txp,
 677                                  int work_to_do)
 678 {
 679         RING_IDX cons = queue->tx.req_cons;
 680         int slots = 0;
 681         int drop_err = 0;
 682         int more_data;
 683
 684         if (!(first->flags & XEN_NETTXF_more_data))
 685                 return 0;
 686
 687         do {
 688                 struct xen_netif_tx_request dropped_tx = { 0 };
 689
 690                 if (slots >= work_to_do) {
 691                         netdev_err(queue->vif->dev,
 692                                    "Asked for %d slots but exceeds this limit\n",
 693                                    work_to_do);
 694                         xenvif_fatal_tx_err(queue->vif);
 695                         return -ENODATA;
 696                 }
 697
 698                 /* This guest is really using too many slots and
 699                  * considered malicious.
 700                  */
 701                 if (unlikely(slots >= fatal_skb_slots)) {
 702                         netdev_err(queue->vif->dev,
 703                                    "Malicious frontend using %d slots, threshold %u\n",
 704                                    slots, fatal_skb_slots);
 705                         xenvif_fatal_tx_err(queue->vif);
 706                         return -E2BIG;
 707                 }
 708
 709                 /* Xen network protocol had implicit dependency on
 710                  * MAX_SKB_FRAGS. XEN_NETBK_LEGACY_SLOTS_MAX is set to
 711                  * the historical MAX_SKB_FRAGS value 18 to honor the
 712                  * same behavior as before. Any packet using more than
 713                  * 18 slots but less than fatal_skb_slots slots is
 714                  * dropped
 715                  */
 716                 if (!drop_err && slots >= XEN_NETBK_LEGACY_SLOTS_MAX) {
 717                         if (net_ratelimit())
 718                                 netdev_dbg(queue->vif->dev,
 719                                            "Too many slots (%d) exceeding limit (%d), dropping packet\n",
 720                                            slots, XEN_NETBK_LEGACY_SLOTS_MAX);
 721                         drop_err = -E2BIG;
 722                 }
 723
 724                 if (drop_err)
 725                         txp = &dropped_tx;
 726
 727                 memcpy(txp, RING_GET_REQUEST(&queue->tx, cons + slots),
 728                        sizeof(*txp));
 729
 730                 /* If the guest submitted a frame >= 64 KiB then
 731                  * first->size overflowed and following slots will
 732                  * appear to be larger than the frame.
 733                  *
 734                  * This cannot be fatal error as there are buggy
 735                  * frontends that do this.
 736                  *
 737                  * Consume all slots and drop the packet.
 738                  */
 739                 if (!drop_err && txp->size > first->size) {
 740                         if (net_ratelimit())
 741                                 netdev_dbg(queue->vif->dev,
 742                                            "Invalid tx request, slot size %u > remaining size %u\n",
 743                                            txp->size, first->size);
 744                         drop_err = -EIO;
 745                 }
 746
 747                 first->size -= txp->size;
 748                 slots++;
 749
 750                 if (unlikely((txp->offset + txp->size) > PAGE_SIZE)) {
 751                         netdev_err(queue->vif->dev, "Cross page boundary, txp->offset: %u, size: %u\n",
 752                                  txp->offset, txp->size);
 753                         xenvif_fatal_tx_err(queue->vif);
 754                         return -EINVAL;
 755                 }
 756
 757                 more_data = txp->flags & XEN_NETTXF_more_data;
 758
 759                 if (!drop_err)
 760                         txp++;
 761
 762         } while (more_data);
 763
 764         if (drop_err) {
 765                 xenvif_tx_err(queue, first, cons + slots);
 766                 return drop_err;
 767         }
 768
 769         return slots;
 770 }
 771
 772
 773 struct xenvif_tx_cb {
 774         u16 pending_idx;
 775 };
 776
 777 #define XENVIF_TX_CB(skb) ((struct xenvif_tx_cb *)(skb)->cb)
 778
 779 static inline void xenvif_tx_create_map_op(struct xenvif_queue *queue,
 780                                           u16 pending_idx,
 781                                           struct xen_netif_tx_request *txp,
 782                                           struct gnttab_map_grant_ref *mop)
 783 {
 784         queue->pages_to_map[mop-queue->tx_map_ops] = queue->mmap_pages[pending_idx];
 785         gnttab_set_map_op(mop, idx_to_kaddr(queue, pending_idx),
 786                           GNTMAP_host_map | GNTMAP_readonly,
 787                           txp->gref, queue->vif->domid);
 788
 789         memcpy(&queue->pending_tx_info[pending_idx].req, txp,
 790                sizeof(*txp));
 791 }
 792
 793 static inline struct sk_buff *xenvif_alloc_skb(unsigned int size)
 794 {
 795         struct sk_buff *skb =
 796                 alloc_skb(size + NET_SKB_PAD + NET_IP_ALIGN,
 797                           GFP_ATOMIC | __GFP_NOWARN);
 798         if (unlikely(skb == NULL))
 799                 return NULL;
 800
 801         /* Packets passed to netif_rx() must have some headroom. */
 802         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
 803
 804         /* Initialize it here to avoid later surprises */
 805         skb_shinfo(skb)->destructor_arg = NULL;
 806
 807         return skb;
 808 }
 809
 810 static struct gnttab_map_grant_ref *xenvif_get_requests(struct xenvif_queue *queue,
 811                                                         struct sk_buff *skb,
 812                                                         struct xen_netif_tx_request *txp,
 813                                                         struct gnttab_map_grant_ref *gop)
 814 {
 815         struct skb_shared_info *shinfo = skb_shinfo(skb);
 816         skb_frag_t *frags = shinfo->frags;
 817         u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
 818         int start;
 819         pending_ring_idx_t index;
 820         unsigned int nr_slots, frag_overflow = 0;
 821
 822         /* At this point shinfo->nr_frags is in fact the number of
 823          * slots, which can be as large as XEN_NETBK_LEGACY_SLOTS_MAX.
 824          */
 825         if (shinfo->nr_frags > MAX_SKB_FRAGS) {
 826                 frag_overflow = shinfo->nr_frags - MAX_SKB_FRAGS;
 827                 BUG_ON(frag_overflow > MAX_SKB_FRAGS);
 828                 shinfo->nr_frags = MAX_SKB_FRAGS;
 829         }
 830         nr_slots = shinfo->nr_frags;
 831
 832         /* Skip first skb fragment if it is on same page as header fragment. */
 833         start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
 834
 835         for (shinfo->nr_frags = start; shinfo->nr_frags < nr_slots;
 836              shinfo->nr_frags++, txp++, gop++) {
 837                 index = pending_index(queue->pending_cons++);
 838                 pending_idx = queue->pending_ring[index];
 839                 xenvif_tx_create_map_op(queue, pending_idx, txp, gop);
 840                 frag_set_pending_idx(&frags[shinfo->nr_frags], pending_idx);
 841         }
 842
 843         if (frag_overflow) {
 844                 struct sk_buff *nskb = xenvif_alloc_skb(0);
 845                 if (unlikely(nskb == NULL)) {
 846                         if (net_ratelimit())
 847                                 netdev_err(queue->vif->dev,
 848                                            "Can't allocate the frag_list skb.\n");
 849                         return NULL;
 850                 }
 851
 852                 shinfo = skb_shinfo(nskb);
 853                 frags = shinfo->frags;
 854
 855                 for (shinfo->nr_frags = 0; shinfo->nr_frags < frag_overflow;
 856                      shinfo->nr_frags++, txp++, gop++) {
 857                         index = pending_index(queue->pending_cons++);
 858                         pending_idx = queue->pending_ring[index];
 859                         xenvif_tx_create_map_op(queue, pending_idx, txp, gop);
 860                         frag_set_pending_idx(&frags[shinfo->nr_frags],
 861                                              pending_idx);
 862                 }
 863
 864                 skb_shinfo(skb)->frag_list = nskb;
 865         }
 866
 867         return gop;
 868 }
 869
 870 static inline void xenvif_grant_handle_set(struct xenvif_queue *queue,
 871                                            u16 pending_idx,
 872                                            grant_handle_t handle)
 873 {
 874         if (unlikely(queue->grant_tx_handle[pending_idx] !=
 875                      NETBACK_INVALID_HANDLE)) {
 876                 netdev_err(queue->vif->dev,
 877                            "Trying to overwrite active handle! pending_idx: 0x%x\n",
 878                            pending_idx);
 879                 BUG();
 880         }
 881         queue->grant_tx_handle[pending_idx] = handle;
 882 }
 883
 884 static inline void xenvif_grant_handle_reset(struct xenvif_queue *queue,
 885                                              u16 pending_idx)
 886 {
 887         if (unlikely(queue->grant_tx_handle[pending_idx] ==
 888                      NETBACK_INVALID_HANDLE)) {
 889                 netdev_err(queue->vif->dev,
 890                            "Trying to unmap invalid handle! pending_idx: 0x%x\n",
 891                            pending_idx);
 892                 BUG();
 893         }
 894         queue->grant_tx_handle[pending_idx] = NETBACK_INVALID_HANDLE;
 895 }
 896
 897 static int xenvif_tx_check_gop(struct xenvif_queue *queue,
 898                                struct sk_buff *skb,
 899                                struct gnttab_map_grant_ref **gopp_map,
 900                                struct gnttab_copy **gopp_copy)
 901 {
 902         struct gnttab_map_grant_ref *gop_map = *gopp_map;
 903         u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
 904         /* This always points to the shinfo of the skb being checked, which
 905          * could be either the first or the one on the frag_list
 906          */
 907         struct skb_shared_info *shinfo = skb_shinfo(skb);
 908         /* If this is non-NULL, we are currently checking the frag_list skb, and
 909          * this points to the shinfo of the first one
 910          */
 911         struct skb_shared_info *first_shinfo = NULL;
 912         int nr_frags = shinfo->nr_frags;
 913         const bool sharedslot = nr_frags &&
 914                                 frag_get_pending_idx(&shinfo->frags[0]) == pending_idx;
 915         int i, err;
 916
 917         /* Check status of header. */
 918         err = (*gopp_copy)->status;
 919         if (unlikely(err)) {
 920                 if (net_ratelimit())
 921                         netdev_dbg(queue->vif->dev,
 922                                    "Grant copy of header failed! status: %d pending_idx: %u ref: %u\n",
 923                                    (*gopp_copy)->status,
 924                                    pending_idx,
 925                                    (*gopp_copy)->source.u.ref);
 926                 /* The first frag might still have this slot mapped */
 927                 if (!sharedslot)
 928                         xenvif_idx_release(queue, pending_idx,
 929                                            XEN_NETIF_RSP_ERROR);
 930         }
 931         (*gopp_copy)++;
 932
 933 check_frags:
 934         for (i = 0; i < nr_frags; i++, gop_map++) {
 935                 int j, newerr;
 936
 937                 pending_idx = frag_get_pending_idx(&shinfo->frags[i]);
 938
 939                 /* Check error status: if okay then remember grant handle. */
 940                 newerr = gop_map->status;
 941
 942                 if (likely(!newerr)) {
 943                         xenvif_grant_handle_set(queue,
 944                                                 pending_idx,
 945                                                 gop_map->handle);
 946                         /* Had a previous error? Invalidate this fragment. */
 947                         if (unlikely(err)) {
 948                                 xenvif_idx_unmap(queue, pending_idx);
 949                                 /* If the mapping of the first frag was OK, but
 950                                  * the header's copy failed, and they are
 951                                  * sharing a slot, send an error
 952                                  */
 953                                 if (i == 0 && sharedslot)
 954                                         xenvif_idx_release(queue, pending_idx,
 955                                                            XEN_NETIF_RSP_ERROR);
 956                                 else
 957                                         xenvif_idx_release(queue, pending_idx,
 958                                                            XEN_NETIF_RSP_OKAY);
 959                         }
 960                         continue;
 961                 }
 962
 963                 /* Error on this fragment: respond to client with an error. */
 964                 if (net_ratelimit())
 965                         netdev_dbg(queue->vif->dev,
 966                                    "Grant map of %d. frag failed! status: %d pending_idx: %u ref: %u\n",
 967                                    i,
 968                                    gop_map->status,
 969                                    pending_idx,
 970                                    gop_map->ref);
 971
 972                 xenvif_idx_release(queue, pending_idx, XEN_NETIF_RSP_ERROR);
 973
 974                 /* Not the first error? Preceding frags already invalidated. */
 975                 if (err)
 976                         continue;
 977
 978                 /* First error: if the header haven't shared a slot with the
 979                  * first frag, release it as well.
 980                  */
 981                 if (!sharedslot)
 982                         xenvif_idx_release(queue,
 983                                            XENVIF_TX_CB(skb)->pending_idx,
 984                                            XEN_NETIF_RSP_OKAY);
 985
 986                 /* Invalidate preceding fragments of this skb. */
 987                 for (j = 0; j < i; j++) {
 988                         pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
 989                         xenvif_idx_unmap(queue, pending_idx);
 990                         xenvif_idx_release(queue, pending_idx,
 991                                            XEN_NETIF_RSP_OKAY);
 992                 }
 993
 994                 /* And if we found the error while checking the frag_list, unmap
 995                  * the first skb's frags
 996                  */
 997                 if (first_shinfo) {
 998                         for (j = 0; j < first_shinfo->nr_frags; j++) {
 999                                 pending_idx = frag_get_pending_idx(&first_shinfo->frags[j]);
1000                                 xenvif_idx_unmap(queue, pending_idx);
1001                                 xenvif_idx_release(queue, pending_idx,
1002                                                    XEN_NETIF_RSP_OKAY);
1003                         }
1004                 }
1005
1006                 /* Remember the error: invalidate all subsequent fragments. */
1007                 err = newerr;
1008         }
1009
1010         if (skb_has_frag_list(skb) && !first_shinfo) {
1011                 first_shinfo = skb_shinfo(skb);
1012                 shinfo = skb_shinfo(skb_shinfo(skb)->frag_list);
1013                 nr_frags = shinfo->nr_frags;
1014
1015                 goto check_frags;
1016         }
1017
1018         *gopp_map = gop_map;
1019         return err;
1020 }
1021
1022 static void xenvif_fill_frags(struct xenvif_queue *queue, struct sk_buff *skb)
1023 {
1024         struct skb_shared_info *shinfo = skb_shinfo(skb);
1025         int nr_frags = shinfo->nr_frags;
1026         int i;
1027         u16 prev_pending_idx = INVALID_PENDING_IDX;
1028
1029         for (i = 0; i < nr_frags; i++) {
1030                 skb_frag_t *frag = shinfo->frags + i;
1031                 struct xen_netif_tx_request *txp;
1032                 struct page *page;
1033                 u16 pending_idx;
1034
1035                 pending_idx = frag_get_pending_idx(frag);
1036
1037                 /* If this is not the first frag, chain it to the previous*/
1038                 if (prev_pending_idx == INVALID_PENDING_IDX)
1039                         skb_shinfo(skb)->destructor_arg =
1040                                 &callback_param(queue, pending_idx);
1041                 else
1042                         callback_param(queue, prev_pending_idx).ctx =
1043                                 &callback_param(queue, pending_idx);
1044
1045                 callback_param(queue, pending_idx).ctx = NULL;
1046                 prev_pending_idx = pending_idx;
1047
1048                 txp = &queue->pending_tx_info[pending_idx].req;
1049                 page = virt_to_page(idx_to_kaddr(queue, pending_idx));
1050                 __skb_fill_page_desc(skb, i, page, txp->offset, txp->size);
1051                 skb->len += txp->size;
1052                 skb->data_len += txp->size;
1053                 skb->truesize += txp->size;
1054
1055                 /* Take an extra reference to offset network stack's put_page */
1056                 get_page(queue->mmap_pages[pending_idx]);
1057         }
1058 }
1059
1060 static int xenvif_get_extras(struct xenvif_queue *queue,
1061                                 struct xen_netif_extra_info *extras,
1062                                 int work_to_do)
1063 {
1064         struct xen_netif_extra_info extra;
1065         RING_IDX cons = queue->tx.req_cons;
1066
1067         do {
1068                 if (unlikely(work_to_do-- <= 0)) {
1069                         netdev_err(queue->vif->dev, "Missing extra info\n");
1070                         xenvif_fatal_tx_err(queue->vif);
1071                         return -EBADR;
1072                 }
1073
1074                 memcpy(&extra, RING_GET_REQUEST(&queue->tx, cons),
1075                        sizeof(extra));
1076                 if (unlikely(!extra.type ||
1077                              extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
1078                         queue->tx.req_cons = ++cons;
1079                         netdev_err(queue->vif->dev,
1080                                    "Invalid extra type: %d\n", extra.type);
1081                         xenvif_fatal_tx_err(queue->vif);
1082                         return -EINVAL;
1083                 }
1084
1085                 memcpy(&extras[extra.type - 1], &extra, sizeof(extra));
1086                 queue->tx.req_cons = ++cons;
1087         } while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE);
1088
1089         return work_to_do;
1090 }
1091
1092 static int xenvif_set_skb_gso(struct xenvif *vif,
1093                               struct sk_buff *skb,
1094                               struct xen_netif_extra_info *gso)
1095 {
1096         if (!gso->u.gso.size) {
1097                 netdev_err(vif->dev, "GSO size must not be zero.\n");
1098                 xenvif_fatal_tx_err(vif);
1099                 return -EINVAL;
1100         }
1101
1102         switch (gso->u.gso.type) {
1103         case XEN_NETIF_GSO_TYPE_TCPV4:
1104                 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
1105                 break;
1106         case XEN_NETIF_GSO_TYPE_TCPV6:
1107                 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
1108                 break;
1109         default:
1110                 netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
1111                 xenvif_fatal_tx_err(vif);
1112                 return -EINVAL;
1113         }
1114
1115         skb_shinfo(skb)->gso_size = gso->u.gso.size;
1116         /* gso_segs will be calculated later */
1117
1118         return 0;
1119 }
1120
1121 static int checksum_setup(struct xenvif_queue *queue, struct sk_buff *skb)
1122 {
1123         bool recalculate_partial_csum = false;
1124
1125         /* A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
1126          * peers can fail to set NETRXF_csum_blank when sending a GSO
1127          * frame. In this case force the SKB to CHECKSUM_PARTIAL and
1128          * recalculate the partial checksum.
1129          */
1130         if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
1131                 queue->stats.rx_gso_checksum_fixup++;
1132                 skb->ip_summed = CHECKSUM_PARTIAL;
1133                 recalculate_partial_csum = true;
1134         }
1135
1136         /* A non-CHECKSUM_PARTIAL SKB does not require setup. */
1137         if (skb->ip_summed != CHECKSUM_PARTIAL)
1138                 return 0;
1139
1140         return skb_checksum_setup(skb, recalculate_partial_csum);
1141 }
1142
1143 static bool tx_credit_exceeded(struct xenvif_queue *queue, unsigned size)
1144 {
1145         u64 now = get_jiffies_64();
1146         u64 next_credit = queue->credit_window_start +
1147                 msecs_to_jiffies(queue->credit_usec / 1000);
1148
1149         /* Timer could already be pending in rare cases. */
1150         if (timer_pending(&queue->credit_timeout))
1151                 return true;
1152
1153         /* Passed the point where we can replenish credit? */
1154         if (time_after_eq64(now, next_credit)) {
1155                 queue->credit_window_start = now;
1156                 tx_add_credit(queue);
1157         }
1158
1159         /* Still too big to send right now? Set a callback. */
1160         if (size > queue->remaining_credit) {
1161                 queue->credit_timeout.data     =
1162                         (unsigned long)queue;
1163                 mod_timer(&queue->credit_timeout,
1164                           next_credit);
1165                 queue->credit_window_start = next_credit;
1166
1167                 return true;
1168         }
1169
1170         return false;
1171 }
1172
1173 static void xenvif_tx_build_gops(struct xenvif_queue *queue,
1174                                      int budget,
1175                                      unsigned *copy_ops,
1176                                      unsigned *map_ops)
1177 {
1178         struct gnttab_map_grant_ref *gop = queue->tx_map_ops, *request_gop;
1179         struct sk_buff *skb;
1180         int ret;
1181
1182         while (skb_queue_len(&queue->tx_queue) < budget) {
1183                 struct xen_netif_tx_request txreq;
1184                 struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX];
1185                 struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
1186                 u16 pending_idx;
1187                 RING_IDX idx;
1188                 int work_to_do;
1189                 unsigned int data_len;
1190                 pending_ring_idx_t index;
1191
1192                 if (queue->tx.sring->req_prod - queue->tx.req_cons >
1193                     XEN_NETIF_TX_RING_SIZE) {
1194                         netdev_err(queue->vif->dev,
1195                                    "Impossible number of requests. "
1196                                    "req_prod %d, req_cons %d, size %ld\n",
1197                                    queue->tx.sring->req_prod, queue->tx.req_cons,
1198                                    XEN_NETIF_TX_RING_SIZE);
1199                         xenvif_fatal_tx_err(queue->vif);
1200                         break;
1201                 }
1202
1203                 work_to_do = RING_HAS_UNCONSUMED_REQUESTS(&queue->tx);
1204                 if (!work_to_do)
1205                         break;
1206
1207                 idx = queue->tx.req_cons;
1208                 rmb(); /* Ensure that we see the request before we copy it. */
1209                 memcpy(&txreq, RING_GET_REQUEST(&queue->tx, idx), sizeof(txreq));
1210
1211                 /* Credit-based scheduling. */
1212                 if (txreq.size > queue->remaining_credit &&
1213                     tx_credit_exceeded(queue, txreq.size))
1214                         break;
1215
1216                 queue->remaining_credit -= txreq.size;
1217
1218                 work_to_do--;
1219                 queue->tx.req_cons = ++idx;
1220
1221                 memset(extras, 0, sizeof(extras));
1222                 if (txreq.flags & XEN_NETTXF_extra_info) {
1223                         work_to_do = xenvif_get_extras(queue, extras,
1224                                                        work_to_do);
1225                         idx = queue->tx.req_cons;
1226                         if (unlikely(work_to_do < 0))
1227                                 break;
1228                 }
1229
1230                 ret = xenvif_count_requests(queue, &txreq, txfrags, work_to_do);
1231                 if (unlikely(ret < 0))
1232                         break;
1233
1234                 idx += ret;
1235
1236                 if (unlikely(txreq.size < ETH_HLEN)) {
1237                         netdev_dbg(queue->vif->dev,
1238                                    "Bad packet size: %d\n", txreq.size);
1239                         xenvif_tx_err(queue, &txreq, idx);
1240                         break;
1241                 }
1242
1243                 /* No crossing a page as the payload mustn't fragment. */
1244                 if (unlikely((txreq.offset + txreq.size) > PAGE_SIZE)) {
1245                         netdev_err(queue->vif->dev,
1246                                    "txreq.offset: %u, size: %u, end: %lu\n",
1247                                    txreq.offset, txreq.size,
1248                                    (unsigned long)(txreq.offset&~PAGE_MASK) + txreq.size);
1249                         xenvif_fatal_tx_err(queue->vif);
1250                         break;
1251                 }
1252
1253                 index = pending_index(queue->pending_cons);
1254                 pending_idx = queue->pending_ring[index];
1255
1256                 data_len = (txreq.size > XEN_NETBACK_TX_COPY_LEN &&
1257                             ret < XEN_NETBK_LEGACY_SLOTS_MAX) ?
1258                         XEN_NETBACK_TX_COPY_LEN : txreq.size;
1259
1260                 skb = xenvif_alloc_skb(data_len);
1261                 if (unlikely(skb == NULL)) {
1262                         netdev_dbg(queue->vif->dev,
1263                                    "Can't allocate a skb in start_xmit.\n");
1264                         xenvif_tx_err(queue, &txreq, idx);
1265                         break;
1266                 }
1267
1268                 if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type) {
1269                         struct xen_netif_extra_info *gso;
1270                         gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
1271
1272                         if (xenvif_set_skb_gso(queue->vif, skb, gso)) {
1273                                 /* Failure in xenvif_set_skb_gso is fatal. */
1274                                 kfree_skb(skb);
1275                                 break;
1276                         }
1277                 }
1278
1279                 XENVIF_TX_CB(skb)->pending_idx = pending_idx;
1280
1281                 __skb_put(skb, data_len);
1282                 queue->tx_copy_ops[*copy_ops].source.u.ref = txreq.gref;
1283                 queue->tx_copy_ops[*copy_ops].source.domid = queue->vif->domid;
1284                 queue->tx_copy_ops[*copy_ops].source.offset = txreq.offset;
1285
1286                 queue->tx_copy_ops[*copy_ops].dest.u.gmfn =
1287                         virt_to_mfn(skb->data);
1288                 queue->tx_copy_ops[*copy_ops].dest.domid = DOMID_SELF;
1289                 queue->tx_copy_ops[*copy_ops].dest.offset =
1290                         offset_in_page(skb->data);
1291
1292                 queue->tx_copy_ops[*copy_ops].len = data_len;
1293                 queue->tx_copy_ops[*copy_ops].flags = GNTCOPY_source_gref;
1294
1295                 (*copy_ops)++;
1296
1297                 skb_shinfo(skb)->nr_frags = ret;
1298                 if (data_len < txreq.size) {
1299                         skb_shinfo(skb)->nr_frags++;
1300                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1301                                              pending_idx);
1302                         xenvif_tx_create_map_op(queue, pending_idx, &txreq, gop);
1303                         gop++;
1304                 } else {
1305                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1306                                              INVALID_PENDING_IDX);
1307                         memcpy(&queue->pending_tx_info[pending_idx].req, &txreq,
1308                                sizeof(txreq));
1309                 }
1310
1311                 queue->pending_cons++;
1312
1313                 request_gop = xenvif_get_requests(queue, skb, txfrags, gop);
1314                 if (request_gop == NULL) {
1315                         kfree_skb(skb);
1316                         xenvif_tx_err(queue, &txreq, idx);
1317                         break;
1318                 }
1319                 gop = request_gop;
1320
1321                 __skb_queue_tail(&queue->tx_queue, skb);
1322
1323                 queue->tx.req_cons = idx;
1324
1325                 if (((gop-queue->tx_map_ops) >= ARRAY_SIZE(queue->tx_map_ops)) ||
1326                     (*copy_ops >= ARRAY_SIZE(queue->tx_copy_ops)))
1327                         break;
1328         }
1329
1330         (*map_ops) = gop - queue->tx_map_ops;
1331         return;
1332 }
1333
1334 /* Consolidate skb with a frag_list into a brand new one with local pages on
1335  * frags. Returns 0 or -ENOMEM if can't allocate new pages.
1336  */
1337 static int xenvif_handle_frag_list(struct xenvif_queue *queue, struct sk_buff *skb)
1338 {
1339         unsigned int offset = skb_headlen(skb);
1340         skb_frag_t frags[MAX_SKB_FRAGS];
1341         int i, f;
1342         struct ubuf_info *uarg;
1343         struct sk_buff *nskb = skb_shinfo(skb)->frag_list;
1344
1345         queue->stats.tx_zerocopy_sent += 2;
1346         queue->stats.tx_frag_overflow++;
1347
1348         xenvif_fill_frags(queue, nskb);
1349         /* Subtract frags size, we will correct it later */
1350         skb->truesize -= skb->data_len;
1351         skb->len += nskb->len;
1352         skb->data_len += nskb->len;
1353
1354         /* create a brand new frags array and coalesce there */
1355         for (i = 0; offset < skb->len; i++) {
1356                 struct page *page;
1357                 unsigned int len;
1358
1359                 BUG_ON(i >= MAX_SKB_FRAGS);
1360                 page = alloc_page(GFP_ATOMIC);
1361                 if (!page) {
1362                         int j;
1363                         skb->truesize += skb->data_len;
1364                         for (j = 0; j < i; j++)
1365                                 put_page(frags[j].page.p);
1366                         return -ENOMEM;
1367                 }
1368
1369                 if (offset + PAGE_SIZE < skb->len)
1370                         len = PAGE_SIZE;
1371                 else
1372                         len = skb->len - offset;
1373                 if (skb_copy_bits(skb, offset, page_address(page), len))
1374                         BUG();
1375
1376                 offset += len;
1377                 frags[i].page.p = page;
1378                 frags[i].page_offset = 0;
1379                 skb_frag_size_set(&frags[i], len);
1380         }
1381
1382         /* Copied all the bits from the frag list -- free it. */
1383         skb_frag_list_init(skb);
1384         xenvif_skb_zerocopy_prepare(queue, nskb);
1385         kfree_skb(nskb);
1386
1387         /* Release all the original (foreign) frags. */
1388         for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
1389                 skb_frag_unref(skb, f);
1390         uarg = skb_shinfo(skb)->destructor_arg;
1391         /* increase inflight counter to offset decrement in callback */
1392         atomic_inc(&queue->inflight_packets);
1393         uarg->callback(uarg, true);
1394         skb_shinfo(skb)->destructor_arg = NULL;
1395
1396         /* Fill the skb with the new (local) frags. */
1397         memcpy(skb_shinfo(skb)->frags, frags, i * sizeof(skb_frag_t));
1398         skb_shinfo(skb)->nr_frags = i;
1399         skb->truesize += i * PAGE_SIZE;
1400
1401         return 0;
1402 }
1403
1404 static int xenvif_tx_submit(struct xenvif_queue *queue)
1405 {
1406         struct gnttab_map_grant_ref *gop_map = queue->tx_map_ops;
1407         struct gnttab_copy *gop_copy = queue->tx_copy_ops;
1408         struct sk_buff *skb;
1409         int work_done = 0;
1410
1411         while ((skb = __skb_dequeue(&queue->tx_queue)) != NULL) {
1412                 struct xen_netif_tx_request *txp;
1413                 u16 pending_idx;
1414                 unsigned data_len;
1415
1416                 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
1417                 txp = &queue->pending_tx_info[pending_idx].req;
1418
1419                 /* Check the remap error code. */
1420                 if (unlikely(xenvif_tx_check_gop(queue, skb, &gop_map, &gop_copy))) {
1421                         /* If there was an error, xenvif_tx_check_gop is
1422                          * expected to release all the frags which were mapped,
1423                          * so kfree_skb shouldn't do it again
1424                          */
1425                         skb_shinfo(skb)->nr_frags = 0;
1426                         if (skb_has_frag_list(skb)) {
1427                                 struct sk_buff *nskb =
1428                                                 skb_shinfo(skb)->frag_list;
1429                                 skb_shinfo(nskb)->nr_frags = 0;
1430                         }
1431                         kfree_skb(skb);
1432                         continue;
1433                 }
1434
1435                 data_len = skb->len;
1436                 callback_param(queue, pending_idx).ctx = NULL;
1437                 if (data_len < txp->size) {
1438                         /* Append the packet payload as a fragment. */
1439                         txp->offset += data_len;
1440                         txp->size -= data_len;
1441                 } else {
1442                         /* Schedule a response immediately. */
1443                         xenvif_idx_release(queue, pending_idx,
1444                                            XEN_NETIF_RSP_OKAY);
1445                 }
1446
1447                 if (txp->flags & XEN_NETTXF_csum_blank)
1448                         skb->ip_summed = CHECKSUM_PARTIAL;
1449                 else if (txp->flags & XEN_NETTXF_data_validated)
1450                         skb->ip_summed = CHECKSUM_UNNECESSARY;
1451
1452                 xenvif_fill_frags(queue, skb);
1453
1454                 if (unlikely(skb_has_frag_list(skb))) {
1455                         if (xenvif_handle_frag_list(queue, skb)) {
1456                                 if (net_ratelimit())
1457                                         netdev_err(queue->vif->dev,
1458                                                    "Not enough memory to consolidate frag_list!\n");
1459                                 xenvif_skb_zerocopy_prepare(queue, skb);
1460                                 kfree_skb(skb);
1461                                 continue;
1462                         }
1463                 }
1464
1465                 skb->dev      = queue->vif->dev;
1466                 skb->protocol = eth_type_trans(skb, skb->dev);
1467                 skb_reset_network_header(skb);
1468
1469                 if (checksum_setup(queue, skb)) {
1470                         netdev_dbg(queue->vif->dev,
1471                                    "Can't setup checksum in net_tx_action\n");
1472                         /* We have to set this flag to trigger the callback */
1473                         if (skb_shinfo(skb)->destructor_arg)
1474                                 xenvif_skb_zerocopy_prepare(queue, skb);
1475                         kfree_skb(skb);
1476                         continue;
1477                 }
1478
1479                 skb_probe_transport_header(skb, 0);
1480
1481                 /* If the packet is GSO then we will have just set up the
1482                  * transport header offset in checksum_setup so it's now
1483                  * straightforward to calculate gso_segs.
1484                  */
1485                 if (skb_is_gso(skb)) {
1486                         int mss = skb_shinfo(skb)->gso_size;
1487                         int hdrlen = skb_transport_header(skb) -
1488                                 skb_mac_header(skb) +
1489                                 tcp_hdrlen(skb);
1490
1491                         skb_shinfo(skb)->gso_segs =
1492                                 DIV_ROUND_UP(skb->len - hdrlen, mss);
1493                 }
1494
1495                 queue->stats.rx_bytes += skb->len;
1496                 queue->stats.rx_packets++;
1497
1498                 work_done++;
1499
1500                 /* Set this flag right before netif_receive_skb, otherwise
1501                  * someone might think this packet already left netback, and
1502                  * do a skb_copy_ubufs while we are still in control of the
1503                  * skb. E.g. the __pskb_pull_tail earlier can do such thing.
1504                  */
1505                 if (skb_shinfo(skb)->destructor_arg) {
1506                         xenvif_skb_zerocopy_prepare(queue, skb);
1507                         queue->stats.tx_zerocopy_sent++;
1508                 }
1509
1510                 netif_receive_skb(skb);
1511         }
1512
1513         return work_done;
1514 }
1515
1516 void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success)
1517 {
1518         unsigned long flags;
1519         pending_ring_idx_t index;
1520         struct xenvif_queue *queue = ubuf_to_queue(ubuf);
1521
1522         /* This is the only place where we grab this lock, to protect callbacks
1523          * from each other.
1524          */
1525         spin_lock_irqsave(&queue->callback_lock, flags);
1526         do {
1527                 u16 pending_idx = ubuf->desc;
1528                 ubuf = (struct ubuf_info *) ubuf->ctx;
1529                 BUG_ON(queue->dealloc_prod - queue->dealloc_cons >=
1530                         MAX_PENDING_REQS);
1531                 index = pending_index(queue->dealloc_prod);
1532                 queue->dealloc_ring[index] = pending_idx;
1533                 /* Sync with xenvif_tx_dealloc_action:
1534                  * insert idx then incr producer.
1535                  */
1536                 smp_wmb();
1537                 queue->dealloc_prod++;
1538         } while (ubuf);
1539         wake_up(&queue->dealloc_wq);
1540         spin_unlock_irqrestore(&queue->callback_lock, flags);
1541
1542         if (likely(zerocopy_success))
1543                 queue->stats.tx_zerocopy_success++;
1544         else
1545                 queue->stats.tx_zerocopy_fail++;
1546         xenvif_skb_zerocopy_complete(queue);
1547 }
1548
1549 static inline void xenvif_tx_dealloc_action(struct xenvif_queue *queue)
1550 {
1551         struct gnttab_unmap_grant_ref *gop;
1552         pending_ring_idx_t dc, dp;
1553         u16 pending_idx, pending_idx_release[MAX_PENDING_REQS];
1554         unsigned int i = 0;
1555
1556         dc = queue->dealloc_cons;
1557         gop = queue->tx_unmap_ops;
1558
1559         /* Free up any grants we have finished using */
1560         do {
1561                 dp = queue->dealloc_prod;
1562
1563                 /* Ensure we see all indices enqueued by all
1564                  * xenvif_zerocopy_callback().
1565                  */
1566                 smp_rmb();
1567
1568                 while (dc != dp) {
1569                         BUG_ON(gop - queue->tx_unmap_ops >= MAX_PENDING_REQS);
1570                         pending_idx =
1571                                 queue->dealloc_ring[pending_index(dc++)];
1572
1573                         pending_idx_release[gop - queue->tx_unmap_ops] =
1574                                 pending_idx;
1575                         queue->pages_to_unmap[gop - queue->tx_unmap_ops] =
1576                                 queue->mmap_pages[pending_idx];
1577                         gnttab_set_unmap_op(gop,
1578                                             idx_to_kaddr(queue, pending_idx),
1579                                             GNTMAP_host_map,
1580                                             queue->grant_tx_handle[pending_idx]);
1581                         xenvif_grant_handle_reset(queue, pending_idx);
1582                         ++gop;
1583                 }
1584
1585         } while (dp != queue->dealloc_prod);
1586
1587         queue->dealloc_cons = dc;
1588
1589         if (gop - queue->tx_unmap_ops > 0) {
1590                 int ret;
1591                 ret = gnttab_unmap_refs(queue->tx_unmap_ops,
1592                                         NULL,
1593                                         queue->pages_to_unmap,
1594                                         gop - queue->tx_unmap_ops);
1595                 if (ret) {
1596                         netdev_err(queue->vif->dev, "Unmap fail: nr_ops %tu ret %d\n",
1597                                    gop - queue->tx_unmap_ops, ret);
1598                         for (i = 0; i < gop - queue->tx_unmap_ops; ++i) {
1599                                 if (gop[i].status != GNTST_okay)
1600                                         netdev_err(queue->vif->dev,
1601                                                    " host_addr: 0x%llx handle: 0x%x status: %d\n",
1602                                                    gop[i].host_addr,
1603                                                    gop[i].handle,
1604                                                    gop[i].status);
1605                         }
1606                         BUG();
1607                 }
1608         }
1609
1610         for (i = 0; i < gop - queue->tx_unmap_ops; ++i)
1611                 xenvif_idx_release(queue, pending_idx_release[i],
1612                                    XEN_NETIF_RSP_OKAY);
1613 }
1614
1615
1616 /* Called after netfront has transmitted */
1617 int xenvif_tx_action(struct xenvif_queue *queue, int budget)
1618 {
1619         unsigned nr_mops, nr_cops = 0;
1620         int work_done, ret;
1621
1622         if (unlikely(!tx_work_todo(queue)))
1623                 return 0;
1624
1625         xenvif_tx_build_gops(queue, budget, &nr_cops, &nr_mops);
1626
1627         if (nr_cops == 0)
1628                 return 0;
1629
1630         gnttab_batch_copy(queue->tx_copy_ops, nr_cops);
1631         if (nr_mops != 0) {
1632                 ret = gnttab_map_refs(queue->tx_map_ops,
1633                                       NULL,
1634                                       queue->pages_to_map,
1635                                       nr_mops);
1636                 BUG_ON(ret);
1637         }
1638
1639         work_done = xenvif_tx_submit(queue);
1640
1641         return work_done;
1642 }
1643
1644 static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
1645                                u8 status)
1646 {
1647         struct pending_tx_info *pending_tx_info;
1648         pending_ring_idx_t index;
1649         unsigned long flags;
1650
1651         pending_tx_info = &queue->pending_tx_info[pending_idx];
1652
1653         spin_lock_irqsave(&queue->response_lock, flags);
1654
1655         make_tx_response(queue, &pending_tx_info->req, status);
1656
1657         /* Release the pending index before pusing the Tx response so
1658          * its available before a new Tx request is pushed by the
1659          * frontend.
1660          */
1661         index = pending_index(queue->pending_prod++);
1662         queue->pending_ring[index] = pending_idx;
1663
1664         push_tx_responses(queue);
1665
1666         spin_unlock_irqrestore(&queue->response_lock, flags);
1667 }
1668
1669
1670 static void make_tx_response(struct xenvif_queue *queue,
1671                              struct xen_netif_tx_request *txp,
1672                              s8       st)
1673 {
1674         RING_IDX i = queue->tx.rsp_prod_pvt;
1675         struct xen_netif_tx_response *resp;
1676
1677         resp = RING_GET_RESPONSE(&queue->tx, i);
1678         resp->id     = txp->id;
1679         resp->status = st;
1680
1681         if (txp->flags & XEN_NETTXF_extra_info)
1682                 RING_GET_RESPONSE(&queue->tx, ++i)->status = XEN_NETIF_RSP_NULL;
1683
1684         queue->tx.rsp_prod_pvt = ++i;
1685 }
1686
1687 static void push_tx_responses(struct xenvif_queue *queue)
1688 {
1689         int notify;
1690
1691         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->tx, notify);
1692         if (notify)
1693                 notify_remote_via_irq(queue->tx_irq);
1694 }
1695
1696 static struct xen_netif_rx_response *make_rx_response(struct xenvif_queue *queue,
1697                                              u16      id,
1698                                              s8       st,
1699                                              u16      offset,
1700                                              u16      size,
1701                                              u16      flags)
1702 {
1703         RING_IDX i = queue->rx.rsp_prod_pvt;
1704         struct xen_netif_rx_response *resp;
1705
1706         resp = RING_GET_RESPONSE(&queue->rx, i);
1707         resp->offset     = offset;
1708         resp->flags      = flags;
1709         resp->id         = id;
1710         resp->status     = (s16)size;
1711         if (st < 0)
1712                 resp->status = (s16)st;
1713
1714         queue->rx.rsp_prod_pvt = ++i;
1715
1716         return resp;
1717 }
1718
1719 void xenvif_idx_unmap(struct xenvif_queue *queue, u16 pending_idx)
1720 {
1721         int ret;
1722         struct gnttab_unmap_grant_ref tx_unmap_op;
1723
1724         gnttab_set_unmap_op(&tx_unmap_op,
1725                             idx_to_kaddr(queue, pending_idx),
1726                             GNTMAP_host_map,
1727                             queue->grant_tx_handle[pending_idx]);
1728         xenvif_grant_handle_reset(queue, pending_idx);
1729
1730         ret = gnttab_unmap_refs(&tx_unmap_op, NULL,
1731                                 &queue->mmap_pages[pending_idx], 1);
1732         if (ret) {
1733                 netdev_err(queue->vif->dev,
1734                            "Unmap fail: ret: %d pending_idx: %d host_addr: %llx handle: 0x%x status: %d\n",
1735                            ret,
1736                            pending_idx,
1737                            tx_unmap_op.host_addr,
1738                            tx_unmap_op.handle,
1739                            tx_unmap_op.status);
1740                 BUG();
1741         }
1742 }
1743
1744 static inline int tx_work_todo(struct xenvif_queue *queue)
1745 {
1746         if (likely(RING_HAS_UNCONSUMED_REQUESTS(&queue->tx)))
1747                 return 1;
1748
1749         return 0;
1750 }
1751
1752 static inline bool tx_dealloc_work_todo(struct xenvif_queue *queue)
1753 {
1754         return queue->dealloc_cons != queue->dealloc_prod;
1755 }
1756
1757 void xenvif_unmap_frontend_rings(struct xenvif_queue *queue)
1758 {
1759         if (queue->tx.sring)
1760                 xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(queue->vif),
1761                                         queue->tx.sring);
1762         if (queue->rx.sring)
1763                 xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(queue->vif),
1764                                         queue->rx.sring);
1765 }
1766
1767 int xenvif_map_frontend_rings(struct xenvif_queue *queue,
1768                               grant_ref_t tx_ring_ref,
1769                               grant_ref_t rx_ring_ref)
1770 {
1771         void *addr;
1772         struct xen_netif_tx_sring *txs;
1773         struct xen_netif_rx_sring *rxs;
1774
1775         int err = -ENOMEM;
1776
1777         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
1778                                      &tx_ring_ref, 1, &addr);
1779         if (err)
1780                 goto err;
1781
1782         txs = (struct xen_netif_tx_sring *)addr;
1783         BACK_RING_INIT(&queue->tx, txs, PAGE_SIZE);
1784
1785         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
1786                                      &rx_ring_ref, 1, &addr);
1787         if (err)
1788                 goto err;
1789
1790         rxs = (struct xen_netif_rx_sring *)addr;
1791         BACK_RING_INIT(&queue->rx, rxs, PAGE_SIZE);
1792
1793         return 0;
1794
1795 err:
1796         xenvif_unmap_frontend_rings(queue);
1797         return err;
1798 }
1799
1800 static void xenvif_queue_carrier_off(struct xenvif_queue *queue)
1801 {
1802         struct xenvif *vif = queue->vif;
1803
1804         queue->stalled = true;
1805
1806         /* At least one queue has stalled? Disable the carrier. */
1807         spin_lock(&vif->lock);
1808         if (vif->stalled_queues++ == 0) {
1809                 netdev_info(vif->dev, "Guest Rx stalled");
1810                 netif_carrier_off(vif->dev);
1811         }
1812         spin_unlock(&vif->lock);
1813 }
1814
1815 static void xenvif_queue_carrier_on(struct xenvif_queue *queue)
1816 {
1817         struct xenvif *vif = queue->vif;
1818
1819         queue->last_rx_time = jiffies; /* Reset Rx stall detection. */
1820         queue->stalled = false;
1821
1822         /* All queues are ready? Enable the carrier. */
1823         spin_lock(&vif->lock);
1824         if (--vif->stalled_queues == 0) {
1825                 netdev_info(vif->dev, "Guest Rx ready");
1826                 netif_carrier_on(vif->dev);
1827         }
1828         spin_unlock(&vif->lock);
1829 }
1830
1831 static bool xenvif_rx_queue_stalled(struct xenvif_queue *queue)
1832 {
1833         RING_IDX prod, cons;
1834
1835         prod = queue->rx.sring->req_prod;
1836         cons = queue->rx.req_cons;
1837
1838         return !queue->stalled
1839                 && prod - cons < XEN_NETBK_RX_SLOTS_MAX
1840                 && time_after(jiffies,
1841                               queue->last_rx_time + queue->vif->stall_timeout);
1842 }
1843
1844 static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
1845 {
1846         RING_IDX prod, cons;
1847
1848         prod = queue->rx.sring->req_prod;
1849         cons = queue->rx.req_cons;
1850
1851         return queue->stalled
1852                 && prod - cons >= XEN_NETBK_RX_SLOTS_MAX;
1853 }
1854
1855 static bool xenvif_have_rx_work(struct xenvif_queue *queue)
1856 {
1857         return (!skb_queue_empty(&queue->rx_queue)
1858                 && xenvif_rx_ring_slots_available(queue, XEN_NETBK_RX_SLOTS_MAX))
1859                 || (queue->vif->stall_timeout &&
1860                     (xenvif_rx_queue_stalled(queue)
1861                      || xenvif_rx_queue_ready(queue)))
1862                 || kthread_should_stop()
1863                 || queue->vif->disabled;
1864 }
1865
1866 static long xenvif_rx_queue_timeout(struct xenvif_queue *queue)
1867 {
1868         struct sk_buff *skb;
1869         long timeout;
1870
1871         skb = skb_peek(&queue->rx_queue);
1872         if (!skb)
1873                 return MAX_SCHEDULE_TIMEOUT;
1874
1875         timeout = XENVIF_RX_CB(skb)->expires - jiffies;
1876         return timeout < 0 ? 0 : timeout;
1877 }
1878
1879 /* Wait until the guest Rx thread has work.
1880  *
1881  * The timeout needs to be adjusted based on the current head of the
1882  * queue (and not just the head at the beginning).  In particular, if
1883  * the queue is initially empty an infinite timeout is used and this
1884  * needs to be reduced when a skb is queued.
1885  *
1886  * This cannot be done with wait_event_timeout() because it only
1887  * calculates the timeout once.
1888  */
1889 static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
1890 {
1891         DEFINE_WAIT(wait);
1892
1893         if (xenvif_have_rx_work(queue))
1894                 return;
1895
1896         for (;;) {
1897                 long ret;
1898
1899                 prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
1900                 if (xenvif_have_rx_work(queue))
1901                         break;
1902                 ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
1903                 if (!ret)
1904                         break;
1905         }
1906         finish_wait(&queue->wq, &wait);
1907 }
1908
1909 int xenvif_kthread_guest_rx(void *data)
1910 {
1911         struct xenvif_queue *queue = data;
1912         struct xenvif *vif = queue->vif;
1913
1914         if (!vif->stall_timeout)
1915                 xenvif_queue_carrier_on(queue);
1916
1917         for (;;) {
1918                 xenvif_wait_for_rx_work(queue);
1919
1920                 if (kthread_should_stop())
1921                         break;
1922
1923                 /* This frontend is found to be rogue, disable it in
1924                  * kthread context. Currently this is only set when
1925                  * netback finds out frontend sends malformed packet,
1926                  * but we cannot disable the interface in softirq
1927                  * context so we defer it here, if this thread is
1928                  * associated with queue 0.
1929                  */
1930                 if (unlikely(vif->disabled && queue->id == 0)) {
1931                         xenvif_carrier_off(vif);
1932                         break;
1933                 }
1934
1935                 if (!skb_queue_empty(&queue->rx_queue))
1936                         xenvif_rx_action(queue);
1937
1938                 /* If the guest hasn't provided any Rx slots for a
1939                  * while it's probably not responsive, drop the
1940                  * carrier so packets are dropped earlier.
1941                  */
1942                 if (vif->stall_timeout) {
1943                         if (xenvif_rx_queue_stalled(queue))
1944                                 xenvif_queue_carrier_off(queue);
1945                         else if (xenvif_rx_queue_ready(queue))
1946                                 xenvif_queue_carrier_on(queue);
1947                 }
1948
1949                 /* Queued packets may have foreign pages from other
1950                  * domains.  These cannot be queued indefinitely as
1951                  * this would starve guests of grant refs and transmit
1952                  * slots.
1953                  */
1954                 xenvif_rx_queue_drop_expired(queue);
1955
1956                 xenvif_rx_queue_maybe_wake(queue);
1957
1958                 cond_resched();
1959         }
1960
1961         /* Bin any remaining skbs */
1962         xenvif_rx_queue_purge(queue);
1963
1964         return 0;
1965 }
1966
1967 static bool xenvif_dealloc_kthread_should_stop(struct xenvif_queue *queue)
1968 {
1969         /* Dealloc thread must remain running until all inflight
1970          * packets complete.
1971          */
1972         return kthread_should_stop() &&
1973                 !atomic_read(&queue->inflight_packets);
1974 }
1975
1976 int xenvif_dealloc_kthread(void *data)
1977 {
1978         struct xenvif_queue *queue = data;
1979
1980         for (;;) {
1981                 wait_event_interruptible(queue->dealloc_wq,
1982                                          tx_dealloc_work_todo(queue) ||
1983                                          xenvif_dealloc_kthread_should_stop(queue));
1984                 if (xenvif_dealloc_kthread_should_stop(queue))
1985                         break;
1986
1987                 xenvif_tx_dealloc_action(queue);
1988                 cond_resched();
1989         }
1990
1991         /* Unmap anything remaining*/
1992         if (tx_dealloc_work_todo(queue))
1993                 xenvif_tx_dealloc_action(queue);
1994
1995         return 0;
1996 }
1997
1998 static int __init netback_init(void)
1999 {
2000         int rc = 0;
2001
2002         if (!xen_domain())
2003                 return -ENODEV;
2004
2005         /* Allow as many queues as there are CPUs, by default */
2006         xenvif_max_queues = num_online_cpus();
2007
2008         if (fatal_skb_slots < XEN_NETBK_LEGACY_SLOTS_MAX) {
2009                 pr_info("fatal_skb_slots too small (%d), bump it to XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n",
2010                         fatal_skb_slots, XEN_NETBK_LEGACY_SLOTS_MAX);
2011                 fatal_skb_slots = XEN_NETBK_LEGACY_SLOTS_MAX;
2012         }
2013
2014         rc = xenvif_xenbus_init();
2015         if (rc)
2016                 goto failed_init;
2017
2018 #ifdef CONFIG_DEBUG_FS
2019         xen_netback_dbg_root = debugfs_create_dir("xen-netback", NULL);
2020         if (IS_ERR_OR_NULL(xen_netback_dbg_root))
2021                 pr_warn("Init of debugfs returned %ld!\n",
2022                         PTR_ERR(xen_netback_dbg_root));
2023 #endif /* CONFIG_DEBUG_FS */
2024
2025         return 0;
2026
2027 failed_init:
2028         return rc;
2029 }
2030
2031 module_init(netback_init);
2032
2033 static void __exit netback_fini(void)
2034 {
2035 #ifdef CONFIG_DEBUG_FS
2036         if (!IS_ERR_OR_NULL(xen_netback_dbg_root))
2037                 debugfs_remove_recursive(xen_netback_dbg_root);
2038 #endif /* CONFIG_DEBUG_FS */
2039         xenvif_xenbus_fini();
2040 }
2041 module_exit(netback_fini);
2042
2043 MODULE_LICENSE("Dual BSD/GPL");
2044 MODULE_ALIAS("xen-backend:vif");