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
  48 #include <asm/xen/hypercall.h>
  49 #include <asm/xen/page.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 = 1;
  56 module_param(separate_tx_rx_irq, bool, 0644);
  57
  58 /* When guest ring is filled up, qdisc queues the packets for us, but we have
  59  * to timeout them, otherwise other guests' packets can get stuck there
  60  */
  61 unsigned int rx_drain_timeout_msecs = 10000;
  62 module_param(rx_drain_timeout_msecs, uint, 0444);
  63 unsigned int rx_drain_timeout_jiffies;
  64
  65 unsigned int xenvif_max_queues;
  66 module_param_named(max_queues, xenvif_max_queues, uint, 0644);
  67 MODULE_PARM_DESC(max_queues,
  68                  "Maximum number of queues per virtual interface");
  69
  70 /*
  71  * This is the maximum slots a skb can have. If a guest sends a skb
  72  * which exceeds this limit it is considered malicious.
  73  */
  74 #define FATAL_SKB_SLOTS_DEFAULT 20
  75 static unsigned int fatal_skb_slots = FATAL_SKB_SLOTS_DEFAULT;
  76 module_param(fatal_skb_slots, uint, 0444);
  77
  78 static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
  79                                u8 status);
  80
  81 static void make_tx_response(struct xenvif_queue *queue,
  82                              struct xen_netif_tx_request *txp,
  83                              s8       st);
  84
  85 static inline int tx_work_todo(struct xenvif_queue *queue);
  86 static inline int rx_work_todo(struct xenvif_queue *queue);
  87
  88 static struct xen_netif_rx_response *make_rx_response(struct xenvif_queue *queue,
  89                                              u16      id,
  90                                              s8       st,
  91                                              u16      offset,
  92                                              u16      size,
  93                                              u16      flags);
  94
  95 static inline unsigned long idx_to_pfn(struct xenvif_queue *queue,
  96                                        u16 idx)
  97 {
  98         return page_to_pfn(queue->mmap_pages[idx]);
  99 }
 100
 101 static inline unsigned long idx_to_kaddr(struct xenvif_queue *queue,
 102                                          u16 idx)
 103 {
 104         return (unsigned long)pfn_to_kaddr(idx_to_pfn(queue, idx));
 105 }
 106
 107 #define callback_param(vif, pending_idx) \
 108         (vif->pending_tx_info[pending_idx].callback_struct)
 109
 110 /* Find the containing VIF's structure from a pointer in pending_tx_info array
 111  */
 112 static inline struct xenvif_queue *ubuf_to_queue(const struct ubuf_info *ubuf)
 113 {
 114         u16 pending_idx = ubuf->desc;
 115         struct pending_tx_info *temp =
 116                 container_of(ubuf, struct pending_tx_info, callback_struct);
 117         return container_of(temp - pending_idx,
 118                             struct xenvif_queue,
 119                             pending_tx_info[0]);
 120 }
 121
 122 /* This is a miniumum size for the linear area to avoid lots of
 123  * calls to __pskb_pull_tail() as we set up checksum offsets. The
 124  * value 128 was chosen as it covers all IPv4 and most likely
 125  * IPv6 headers.
 126  */
 127 #define PKT_PROT_LEN 128
 128
 129 static u16 frag_get_pending_idx(skb_frag_t *frag)
 130 {
 131         return (u16)frag->page_offset;
 132 }
 133
 134 static void frag_set_pending_idx(skb_frag_t *frag, u16 pending_idx)
 135 {
 136         frag->page_offset = pending_idx;
 137 }
 138
 139 static inline pending_ring_idx_t pending_index(unsigned i)
 140 {
 141         return i & (MAX_PENDING_REQS-1);
 142 }
 143
 144 bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue, int needed)
 145 {
 146         RING_IDX prod, cons;
 147
 148         do {
 149                 prod = queue->rx.sring->req_prod;
 150                 cons = queue->rx.req_cons;
 151
 152                 if (prod - cons >= needed)
 153                         return true;
 154
 155                 queue->rx.sring->req_event = prod + 1;
 156
 157                 /* Make sure event is visible before we check prod
 158                  * again.
 159                  */
 160                 mb();
 161         } while (queue->rx.sring->req_prod != prod);
 162
 163         return false;
 164 }
 165
 166 /*
 167  * Returns true if we should start a new receive buffer instead of
 168  * adding 'size' bytes to a buffer which currently contains 'offset'
 169  * bytes.
 170  */
 171 static bool start_new_rx_buffer(int offset, unsigned long size, int head,
 172                                 bool full_coalesce)
 173 {
 174         /* simple case: we have completely filled the current buffer. */
 175         if (offset == MAX_BUFFER_OFFSET)
 176                 return true;
 177
 178         /*
 179          * complex case: start a fresh buffer if the current frag
 180          * would overflow the current buffer but only if:
 181          *     (i)   this frag would fit completely in the next buffer
 182          * and (ii)  there is already some data in the current buffer
 183          * and (iii) this is not the head buffer.
 184          * and (iv)  there is no need to fully utilize the buffers
 185          *
 186          * Where:
 187          * - (i) stops us splitting a frag into two copies
 188          *   unless the frag is too large for a single buffer.
 189          * - (ii) stops us from leaving a buffer pointlessly empty.
 190          * - (iii) stops us leaving the first buffer
 191          *   empty. Strictly speaking this is already covered
 192          *   by (ii) but is explicitly checked because
 193          *   netfront relies on the first buffer being
 194          *   non-empty and can crash otherwise.
 195          * - (iv) is needed for skbs which can use up more than MAX_SKB_FRAGS
 196          *   slot
 197          *
 198          * This means we will effectively linearise small
 199          * frags but do not needlessly split large buffers
 200          * into multiple copies tend to give large frags their
 201          * own buffers as before.
 202          */
 203         BUG_ON(size > MAX_BUFFER_OFFSET);
 204         if ((offset + size > MAX_BUFFER_OFFSET) && offset && !head &&
 205             !full_coalesce)
 206                 return true;
 207
 208         return false;
 209 }
 210
 211 struct netrx_pending_operations {
 212         unsigned copy_prod, copy_cons;
 213         unsigned meta_prod, meta_cons;
 214         struct gnttab_copy *copy;
 215         struct xenvif_rx_meta *meta;
 216         int copy_off;
 217         grant_ref_t copy_gref;
 218 };
 219
 220 static struct xenvif_rx_meta *get_next_rx_buffer(struct xenvif_queue *queue,
 221                                                  struct netrx_pending_operations *npo)
 222 {
 223         struct xenvif_rx_meta *meta;
 224         struct xen_netif_rx_request *req;
 225
 226         req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons++);
 227
 228         meta = npo->meta + npo->meta_prod++;
 229         meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
 230         meta->gso_size = 0;
 231         meta->size = 0;
 232         meta->id = req->id;
 233
 234         npo->copy_off = 0;
 235         npo->copy_gref = req->gref;
 236
 237         return meta;
 238 }
 239
 240 struct xenvif_rx_cb {
 241         int meta_slots_used;
 242         bool full_coalesce;
 243 };
 244
 245 #define XENVIF_RX_CB(skb) ((struct xenvif_rx_cb *)(skb)->cb)
 246
 247 /*
 248  * Set up the grant operations for this fragment. If it's a flipping
 249  * interface, we also set up the unmap request from here.
 250  */
 251 static void xenvif_gop_frag_copy(struct xenvif_queue *queue, struct sk_buff *skb,
 252                                  struct netrx_pending_operations *npo,
 253                                  struct page *page, unsigned long size,
 254                                  unsigned long offset, int *head,
 255                                  struct xenvif_queue *foreign_queue,
 256                                  grant_ref_t foreign_gref)
 257 {
 258         struct gnttab_copy *copy_gop;
 259         struct xenvif_rx_meta *meta;
 260         unsigned long bytes;
 261         int gso_type = XEN_NETIF_GSO_TYPE_NONE;
 262
 263         /* Data must not cross a page boundary. */
 264         BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
 265
 266         meta = npo->meta + npo->meta_prod - 1;
 267
 268         /* Skip unused frames from start of page */
 269         page += offset >> PAGE_SHIFT;
 270         offset &= ~PAGE_MASK;
 271
 272         while (size > 0) {
 273                 BUG_ON(offset >= PAGE_SIZE);
 274                 BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
 275
 276                 bytes = PAGE_SIZE - offset;
 277
 278                 if (bytes > size)
 279                         bytes = size;
 280
 281                 if (start_new_rx_buffer(npo->copy_off,
 282                                         bytes,
 283                                         *head,
 284                                         XENVIF_RX_CB(skb)->full_coalesce)) {
 285                         /*
 286                          * Netfront requires there to be some data in the head
 287                          * buffer.
 288                          */
 289                         BUG_ON(*head);
 290
 291                         meta = get_next_rx_buffer(queue, npo);
 292                 }
 293
 294                 if (npo->copy_off + bytes > MAX_BUFFER_OFFSET)
 295                         bytes = MAX_BUFFER_OFFSET - npo->copy_off;
 296
 297                 copy_gop = npo->copy + npo->copy_prod++;
 298                 copy_gop->flags = GNTCOPY_dest_gref;
 299                 copy_gop->len = bytes;
 300
 301                 if (foreign_queue) {
 302                         copy_gop->source.domid = foreign_queue->vif->domid;
 303                         copy_gop->source.u.ref = foreign_gref;
 304                         copy_gop->flags |= GNTCOPY_source_gref;
 305                 } else {
 306                         copy_gop->source.domid = DOMID_SELF;
 307                         copy_gop->source.u.gmfn =
 308                                 virt_to_mfn(page_address(page));
 309                 }
 310                 copy_gop->source.offset = offset;
 311
 312                 copy_gop->dest.domid = queue->vif->domid;
 313                 copy_gop->dest.offset = npo->copy_off;
 314                 copy_gop->dest.u.ref = npo->copy_gref;
 315
 316                 npo->copy_off += bytes;
 317                 meta->size += bytes;
 318
 319                 offset += bytes;
 320                 size -= bytes;
 321
 322                 /* Next frame */
 323                 if (offset == PAGE_SIZE && size) {
 324                         BUG_ON(!PageCompound(page));
 325                         page++;
 326                         offset = 0;
 327                 }
 328
 329                 /* Leave a gap for the GSO descriptor. */
 330                 if (skb_is_gso(skb)) {
 331                         if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
 332                                 gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
 333                         else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
 334                                 gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
 335                 }
 336
 337                 if (*head && ((1 << gso_type) & queue->vif->gso_mask))
 338                         queue->rx.req_cons++;
 339
 340                 *head = 0; /* There must be something in this buffer now. */
 341
 342         }
 343 }
 344
 345 /*
 346  * Find the grant ref for a given frag in a chain of struct ubuf_info's
 347  * skb: the skb itself
 348  * i: the frag's number
 349  * ubuf: a pointer to an element in the chain. It should not be NULL
 350  *
 351  * Returns a pointer to the element in the chain where the page were found. If
 352  * not found, returns NULL.
 353  * See the definition of callback_struct in common.h for more details about
 354  * the chain.
 355  */
 356 static const struct ubuf_info *xenvif_find_gref(const struct sk_buff *const skb,
 357                                                 const int i,
 358                                                 const struct ubuf_info *ubuf)
 359 {
 360         struct xenvif_queue *foreign_queue = ubuf_to_queue(ubuf);
 361
 362         do {
 363                 u16 pending_idx = ubuf->desc;
 364
 365                 if (skb_shinfo(skb)->frags[i].page.p ==
 366                     foreign_queue->mmap_pages[pending_idx])
 367                         break;
 368                 ubuf = (struct ubuf_info *) ubuf->ctx;
 369         } while (ubuf);
 370
 371         return ubuf;
 372 }
 373
 374 /*
 375  * Prepare an SKB to be transmitted to the frontend.
 376  *
 377  * This function is responsible for allocating grant operations, meta
 378  * structures, etc.
 379  *
 380  * It returns the number of meta structures consumed. The number of
 381  * ring slots used is always equal to the number of meta slots used
 382  * plus the number of GSO descriptors used. Currently, we use either
 383  * zero GSO descriptors (for non-GSO packets) or one descriptor (for
 384  * frontend-side LRO).
 385  */
 386 static int xenvif_gop_skb(struct sk_buff *skb,
 387                           struct netrx_pending_operations *npo,
 388                           struct xenvif_queue *queue)
 389 {
 390         struct xenvif *vif = netdev_priv(skb->dev);
 391         int nr_frags = skb_shinfo(skb)->nr_frags;
 392         int i;
 393         struct xen_netif_rx_request *req;
 394         struct xenvif_rx_meta *meta;
 395         unsigned char *data;
 396         int head = 1;
 397         int old_meta_prod;
 398         int gso_type;
 399         const struct ubuf_info *ubuf = skb_shinfo(skb)->destructor_arg;
 400         const struct ubuf_info *const head_ubuf = ubuf;
 401
 402         old_meta_prod = npo->meta_prod;
 403
 404         gso_type = XEN_NETIF_GSO_TYPE_NONE;
 405         if (skb_is_gso(skb)) {
 406                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
 407                         gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
 408                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
 409                         gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
 410         }
 411
 412         /* Set up a GSO prefix descriptor, if necessary */
 413         if ((1 << gso_type) & vif->gso_prefix_mask) {
 414                 req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons++);
 415                 meta = npo->meta + npo->meta_prod++;
 416                 meta->gso_type = gso_type;
 417                 meta->gso_size = skb_shinfo(skb)->gso_size;
 418                 meta->size = 0;
 419                 meta->id = req->id;
 420         }
 421
 422         req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons++);
 423         meta = npo->meta + npo->meta_prod++;
 424
 425         if ((1 << gso_type) & vif->gso_mask) {
 426                 meta->gso_type = gso_type;
 427                 meta->gso_size = skb_shinfo(skb)->gso_size;
 428         } else {
 429                 meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
 430                 meta->gso_size = 0;
 431         }
 432
 433         meta->size = 0;
 434         meta->id = req->id;
 435         npo->copy_off = 0;
 436         npo->copy_gref = req->gref;
 437
 438         data = skb->data;
 439         while (data < skb_tail_pointer(skb)) {
 440                 unsigned int offset = offset_in_page(data);
 441                 unsigned int len = PAGE_SIZE - offset;
 442
 443                 if (data + len > skb_tail_pointer(skb))
 444                         len = skb_tail_pointer(skb) - data;
 445
 446                 xenvif_gop_frag_copy(queue, skb, npo,
 447                                      virt_to_page(data), len, offset, &head,
 448                                      NULL,
 449                                      0);
 450                 data += len;
 451         }
 452
 453         for (i = 0; i < nr_frags; i++) {
 454                 /* This variable also signals whether foreign_gref has a real
 455                  * value or not.
 456                  */
 457                 struct xenvif_queue *foreign_queue = NULL;
 458                 grant_ref_t foreign_gref;
 459
 460                 if ((skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) &&
 461                         (ubuf->callback == &xenvif_zerocopy_callback)) {
 462                         const struct ubuf_info *const startpoint = ubuf;
 463
 464                         /* Ideally ubuf points to the chain element which
 465                          * belongs to this frag. Or if frags were removed from
 466                          * the beginning, then shortly before it.
 467                          */
 468                         ubuf = xenvif_find_gref(skb, i, ubuf);
 469
 470                         /* Try again from the beginning of the list, if we
 471                          * haven't tried from there. This only makes sense in
 472                          * the unlikely event of reordering the original frags.
 473                          * For injected local pages it's an unnecessary second
 474                          * run.
 475                          */
 476                         if (unlikely(!ubuf) && startpoint != head_ubuf)
 477                                 ubuf = xenvif_find_gref(skb, i, head_ubuf);
 478
 479                         if (likely(ubuf)) {
 480                                 u16 pending_idx = ubuf->desc;
 481
 482                                 foreign_queue = ubuf_to_queue(ubuf);
 483                                 foreign_gref =
 484                                         foreign_queue->pending_tx_info[pending_idx].req.gref;
 485                                 /* Just a safety measure. If this was the last
 486                                  * element on the list, the for loop will
 487                                  * iterate again if a local page were added to
 488                                  * the end. Using head_ubuf here prevents the
 489                                  * second search on the chain. Or the original
 490                                  * frags changed order, but that's less likely.
 491                                  * In any way, ubuf shouldn't be NULL.
 492                                  */
 493                                 ubuf = ubuf->ctx ?
 494                                         (struct ubuf_info *) ubuf->ctx :
 495                                         head_ubuf;
 496                         } else
 497                                 /* This frag was a local page, added to the
 498                                  * array after the skb left netback.
 499                                  */
 500                                 ubuf = head_ubuf;
 501                 }
 502                 xenvif_gop_frag_copy(queue, skb, npo,
 503                                      skb_frag_page(&skb_shinfo(skb)->frags[i]),
 504                                      skb_frag_size(&skb_shinfo(skb)->frags[i]),
 505                                      skb_shinfo(skb)->frags[i].page_offset,
 506                                      &head,
 507                                      foreign_queue,
 508                                      foreign_queue ? foreign_gref : UINT_MAX);
 509         }
 510
 511         return npo->meta_prod - old_meta_prod;
 512 }
 513
 514 /*
 515  * This is a twin to xenvif_gop_skb.  Assume that xenvif_gop_skb was
 516  * used to set up the operations on the top of
 517  * netrx_pending_operations, which have since been done.  Check that
 518  * they didn't give any errors and advance over them.
 519  */
 520 static int xenvif_check_gop(struct xenvif *vif, int nr_meta_slots,
 521                             struct netrx_pending_operations *npo)
 522 {
 523         struct gnttab_copy     *copy_op;
 524         int status = XEN_NETIF_RSP_OKAY;
 525         int i;
 526
 527         for (i = 0; i < nr_meta_slots; i++) {
 528                 copy_op = npo->copy + npo->copy_cons++;
 529                 if (copy_op->status != GNTST_okay) {
 530                         netdev_dbg(vif->dev,
 531                                    "Bad status %d from copy to DOM%d.\n",
 532                                    copy_op->status, vif->domid);
 533                         status = XEN_NETIF_RSP_ERROR;
 534                 }
 535         }
 536
 537         return status;
 538 }
 539
 540 static void xenvif_add_frag_responses(struct xenvif_queue *queue, int status,
 541                                       struct xenvif_rx_meta *meta,
 542                                       int nr_meta_slots)
 543 {
 544         int i;
 545         unsigned long offset;
 546
 547         /* No fragments used */
 548         if (nr_meta_slots <= 1)
 549                 return;
 550
 551         nr_meta_slots--;
 552
 553         for (i = 0; i < nr_meta_slots; i++) {
 554                 int flags;
 555                 if (i == nr_meta_slots - 1)
 556                         flags = 0;
 557                 else
 558                         flags = XEN_NETRXF_more_data;
 559
 560                 offset = 0;
 561                 make_rx_response(queue, meta[i].id, status, offset,
 562                                  meta[i].size, flags);
 563         }
 564 }
 565
 566 void xenvif_kick_thread(struct xenvif_queue *queue)
 567 {
 568         wake_up(&queue->wq);
 569 }
 570
 571 static void xenvif_rx_action(struct xenvif_queue *queue)
 572 {
 573         s8 status;
 574         u16 flags;
 575         struct xen_netif_rx_response *resp;
 576         struct sk_buff_head rxq;
 577         struct sk_buff *skb;
 578         LIST_HEAD(notify);
 579         int ret;
 580         unsigned long offset;
 581         bool need_to_notify = false;
 582
 583         struct netrx_pending_operations npo = {
 584                 .copy  = queue->grant_copy_op,
 585                 .meta  = queue->meta,
 586         };
 587
 588         skb_queue_head_init(&rxq);
 589
 590         while ((skb = skb_dequeue(&queue->rx_queue)) != NULL) {
 591                 RING_IDX max_slots_needed;
 592                 RING_IDX old_req_cons;
 593                 RING_IDX ring_slots_used;
 594                 int i;
 595
 596                 /* We need a cheap worse case estimate for the number of
 597                  * slots we'll use.
 598                  */
 599
 600                 max_slots_needed = DIV_ROUND_UP(offset_in_page(skb->data) +
 601                                                 skb_headlen(skb),
 602                                                 PAGE_SIZE);
 603                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 604                         unsigned int size;
 605                         unsigned int offset;
 606
 607                         size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
 608                         offset = skb_shinfo(skb)->frags[i].page_offset;
 609
 610                         /* For a worse-case estimate we need to factor in
 611                          * the fragment page offset as this will affect the
 612                          * number of times xenvif_gop_frag_copy() will
 613                          * call start_new_rx_buffer().
 614                          */
 615                         max_slots_needed += DIV_ROUND_UP(offset + size,
 616                                                          PAGE_SIZE);
 617                 }
 618
 619                 /* To avoid the estimate becoming too pessimal for some
 620                  * frontends that limit posted rx requests, cap the estimate
 621                  * at MAX_SKB_FRAGS. In this case netback will fully coalesce
 622                  * the skb into the provided slots.
 623                  */
 624                 if (max_slots_needed > MAX_SKB_FRAGS) {
 625                         max_slots_needed = MAX_SKB_FRAGS;
 626                         XENVIF_RX_CB(skb)->full_coalesce = true;
 627                 } else {
 628                         XENVIF_RX_CB(skb)->full_coalesce = false;
 629                 }
 630
 631                 /* We may need one more slot for GSO metadata */
 632                 if (skb_is_gso(skb) &&
 633                    (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4 ||
 634                     skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6))
 635                         max_slots_needed++;
 636
 637                 /* If the skb may not fit then bail out now */
 638                 if (!xenvif_rx_ring_slots_available(queue, max_slots_needed)) {
 639                         skb_queue_head(&queue->rx_queue, skb);
 640                         need_to_notify = true;
 641                         queue->rx_last_skb_slots = max_slots_needed;
 642                         break;
 643                 } else
 644                         queue->rx_last_skb_slots = 0;
 645
 646                 old_req_cons = queue->rx.req_cons;
 647                 XENVIF_RX_CB(skb)->meta_slots_used = xenvif_gop_skb(skb, &npo, queue);
 648                 ring_slots_used = queue->rx.req_cons - old_req_cons;
 649
 650                 BUG_ON(ring_slots_used > max_slots_needed);
 651
 652                 __skb_queue_tail(&rxq, skb);
 653         }
 654
 655         BUG_ON(npo.meta_prod > ARRAY_SIZE(queue->meta));
 656
 657         if (!npo.copy_prod)
 658                 goto done;
 659
 660         BUG_ON(npo.copy_prod > MAX_GRANT_COPY_OPS);
 661         gnttab_batch_copy(queue->grant_copy_op, npo.copy_prod);
 662
 663         while ((skb = __skb_dequeue(&rxq)) != NULL) {
 664
 665                 if ((1 << queue->meta[npo.meta_cons].gso_type) &
 666                     queue->vif->gso_prefix_mask) {
 667                         resp = RING_GET_RESPONSE(&queue->rx,
 668                                                  queue->rx.rsp_prod_pvt++);
 669
 670                         resp->flags = XEN_NETRXF_gso_prefix | XEN_NETRXF_more_data;
 671
 672                         resp->offset = queue->meta[npo.meta_cons].gso_size;
 673                         resp->id = queue->meta[npo.meta_cons].id;
 674                         resp->status = XENVIF_RX_CB(skb)->meta_slots_used;
 675
 676                         npo.meta_cons++;
 677                         XENVIF_RX_CB(skb)->meta_slots_used--;
 678                 }
 679
 680
 681                 queue->stats.tx_bytes += skb->len;
 682                 queue->stats.tx_packets++;
 683
 684                 status = xenvif_check_gop(queue->vif,
 685                                           XENVIF_RX_CB(skb)->meta_slots_used,
 686                                           &npo);
 687
 688                 if (XENVIF_RX_CB(skb)->meta_slots_used == 1)
 689                         flags = 0;
 690                 else
 691                         flags = XEN_NETRXF_more_data;
 692
 693                 if (skb->ip_summed == CHECKSUM_PARTIAL) /* local packet? */
 694                         flags |= XEN_NETRXF_csum_blank | XEN_NETRXF_data_validated;
 695                 else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
 696                         /* remote but checksummed. */
 697                         flags |= XEN_NETRXF_data_validated;
 698
 699                 offset = 0;
 700                 resp = make_rx_response(queue, queue->meta[npo.meta_cons].id,
 701                                         status, offset,
 702                                         queue->meta[npo.meta_cons].size,
 703                                         flags);
 704
 705                 if ((1 << queue->meta[npo.meta_cons].gso_type) &
 706                     queue->vif->gso_mask) {
 707                         struct xen_netif_extra_info *gso =
 708                                 (struct xen_netif_extra_info *)
 709                                 RING_GET_RESPONSE(&queue->rx,
 710                                                   queue->rx.rsp_prod_pvt++);
 711
 712                         resp->flags |= XEN_NETRXF_extra_info;
 713
 714                         gso->u.gso.type = queue->meta[npo.meta_cons].gso_type;
 715                         gso->u.gso.size = queue->meta[npo.meta_cons].gso_size;
 716                         gso->u.gso.pad = 0;
 717                         gso->u.gso.features = 0;
 718
 719                         gso->type = XEN_NETIF_EXTRA_TYPE_GSO;
 720                         gso->flags = 0;
 721                 }
 722
 723                 xenvif_add_frag_responses(queue, status,
 724                                           queue->meta + npo.meta_cons + 1,
 725                                           XENVIF_RX_CB(skb)->meta_slots_used);
 726
 727                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->rx, ret);
 728
 729                 need_to_notify |= !!ret;
 730
 731                 npo.meta_cons += XENVIF_RX_CB(skb)->meta_slots_used;
 732                 dev_kfree_skb(skb);
 733         }
 734
 735 done:
 736         if (need_to_notify)
 737                 notify_remote_via_irq(queue->rx_irq);
 738 }
 739
 740 void xenvif_napi_schedule_or_enable_events(struct xenvif_queue *queue)
 741 {
 742         int more_to_do;
 743
 744         RING_FINAL_CHECK_FOR_REQUESTS(&queue->tx, more_to_do);
 745
 746         if (more_to_do)
 747                 napi_schedule(&queue->napi);
 748 }
 749
 750 static void tx_add_credit(struct xenvif_queue *queue)
 751 {
 752         unsigned long max_burst, max_credit;
 753
 754         /*
 755          * Allow a burst big enough to transmit a jumbo packet of up to 128kB.
 756          * Otherwise the interface can seize up due to insufficient credit.
 757          */
 758         max_burst = RING_GET_REQUEST(&queue->tx, queue->tx.req_cons)->size;
 759         max_burst = min(max_burst, 131072UL);
 760         max_burst = max(max_burst, queue->credit_bytes);
 761
 762         /* Take care that adding a new chunk of credit doesn't wrap to zero. */
 763         max_credit = queue->remaining_credit + queue->credit_bytes;
 764         if (max_credit < queue->remaining_credit)
 765                 max_credit = ULONG_MAX; /* wrapped: clamp to ULONG_MAX */
 766
 767         queue->remaining_credit = min(max_credit, max_burst);
 768 }
 769
 770 static void tx_credit_callback(unsigned long data)
 771 {
 772         struct xenvif_queue *queue = (struct xenvif_queue *)data;
 773         tx_add_credit(queue);
 774         xenvif_napi_schedule_or_enable_events(queue);
 775 }
 776
 777 static void xenvif_tx_err(struct xenvif_queue *queue,
 778                           struct xen_netif_tx_request *txp, RING_IDX end)
 779 {
 780         RING_IDX cons = queue->tx.req_cons;
 781         unsigned long flags;
 782
 783         do {
 784                 spin_lock_irqsave(&queue->response_lock, flags);
 785                 make_tx_response(queue, txp, XEN_NETIF_RSP_ERROR);
 786                 spin_unlock_irqrestore(&queue->response_lock, flags);
 787                 if (cons == end)
 788                         break;
 789                 txp = RING_GET_REQUEST(&queue->tx, cons++);
 790         } while (1);
 791         queue->tx.req_cons = cons;
 792 }
 793
 794 static void xenvif_fatal_tx_err(struct xenvif *vif)
 795 {
 796         netdev_err(vif->dev, "fatal error; disabling device\n");
 797         vif->disabled = true;
 798         /* Disable the vif from queue 0's kthread */
 799         if (vif->queues)
 800                 xenvif_kick_thread(&vif->queues[0]);
 801 }
 802
 803 static int xenvif_count_requests(struct xenvif_queue *queue,
 804                                  struct xen_netif_tx_request *first,
 805                                  struct xen_netif_tx_request *txp,
 806                                  int work_to_do)
 807 {
 808         RING_IDX cons = queue->tx.req_cons;
 809         int slots = 0;
 810         int drop_err = 0;
 811         int more_data;
 812
 813         if (!(first->flags & XEN_NETTXF_more_data))
 814                 return 0;
 815
 816         do {
 817                 struct xen_netif_tx_request dropped_tx = { 0 };
 818
 819                 if (slots >= work_to_do) {
 820                         netdev_err(queue->vif->dev,
 821                                    "Asked for %d slots but exceeds this limit\n",
 822                                    work_to_do);
 823                         xenvif_fatal_tx_err(queue->vif);
 824                         return -ENODATA;
 825                 }
 826
 827                 /* This guest is really using too many slots and
 828                  * considered malicious.
 829                  */
 830                 if (unlikely(slots >= fatal_skb_slots)) {
 831                         netdev_err(queue->vif->dev,
 832                                    "Malicious frontend using %d slots, threshold %u\n",
 833                                    slots, fatal_skb_slots);
 834                         xenvif_fatal_tx_err(queue->vif);
 835                         return -E2BIG;
 836                 }
 837
 838                 /* Xen network protocol had implicit dependency on
 839                  * MAX_SKB_FRAGS. XEN_NETBK_LEGACY_SLOTS_MAX is set to
 840                  * the historical MAX_SKB_FRAGS value 18 to honor the
 841                  * same behavior as before. Any packet using more than
 842                  * 18 slots but less than fatal_skb_slots slots is
 843                  * dropped
 844                  */
 845                 if (!drop_err && slots >= XEN_NETBK_LEGACY_SLOTS_MAX) {
 846                         if (net_ratelimit())
 847                                 netdev_dbg(queue->vif->dev,
 848                                            "Too many slots (%d) exceeding limit (%d), dropping packet\n",
 849                                            slots, XEN_NETBK_LEGACY_SLOTS_MAX);
 850                         drop_err = -E2BIG;
 851                 }
 852
 853                 if (drop_err)
 854                         txp = &dropped_tx;
 855
 856                 memcpy(txp, RING_GET_REQUEST(&queue->tx, cons + slots),
 857                        sizeof(*txp));
 858
 859                 /* If the guest submitted a frame >= 64 KiB then
 860                  * first->size overflowed and following slots will
 861                  * appear to be larger than the frame.
 862                  *
 863                  * This cannot be fatal error as there are buggy
 864                  * frontends that do this.
 865                  *
 866                  * Consume all slots and drop the packet.
 867                  */
 868                 if (!drop_err && txp->size > first->size) {
 869                         if (net_ratelimit())
 870                                 netdev_dbg(queue->vif->dev,
 871                                            "Invalid tx request, slot size %u > remaining size %u\n",
 872                                            txp->size, first->size);
 873                         drop_err = -EIO;
 874                 }
 875
 876                 first->size -= txp->size;
 877                 slots++;
 878
 879                 if (unlikely((txp->offset + txp->size) > PAGE_SIZE)) {
 880                         netdev_err(queue->vif->dev, "Cross page boundary, txp->offset: %x, size: %u\n",
 881                                  txp->offset, txp->size);
 882                         xenvif_fatal_tx_err(queue->vif);
 883                         return -EINVAL;
 884                 }
 885
 886                 more_data = txp->flags & XEN_NETTXF_more_data;
 887
 888                 if (!drop_err)
 889                         txp++;
 890
 891         } while (more_data);
 892
 893         if (drop_err) {
 894                 xenvif_tx_err(queue, first, cons + slots);
 895                 return drop_err;
 896         }
 897
 898         return slots;
 899 }
 900
 901
 902 struct xenvif_tx_cb {
 903         u16 pending_idx;
 904 };
 905
 906 #define XENVIF_TX_CB(skb) ((struct xenvif_tx_cb *)(skb)->cb)
 907
 908 static inline void xenvif_tx_create_map_op(struct xenvif_queue *queue,
 909                                           u16 pending_idx,
 910                                           struct xen_netif_tx_request *txp,
 911                                           struct gnttab_map_grant_ref *mop)
 912 {
 913         queue->pages_to_map[mop-queue->tx_map_ops] = queue->mmap_pages[pending_idx];
 914         gnttab_set_map_op(mop, idx_to_kaddr(queue, pending_idx),
 915                           GNTMAP_host_map | GNTMAP_readonly,
 916                           txp->gref, queue->vif->domid);
 917
 918         memcpy(&queue->pending_tx_info[pending_idx].req, txp,
 919                sizeof(*txp));
 920 }
 921
 922 static inline struct sk_buff *xenvif_alloc_skb(unsigned int size)
 923 {
 924         struct sk_buff *skb =
 925                 alloc_skb(size + NET_SKB_PAD + NET_IP_ALIGN,
 926                           GFP_ATOMIC | __GFP_NOWARN);
 927         if (unlikely(skb == NULL))
 928                 return NULL;
 929
 930         /* Packets passed to netif_rx() must have some headroom. */
 931         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
 932
 933         /* Initialize it here to avoid later surprises */
 934         skb_shinfo(skb)->destructor_arg = NULL;
 935
 936         return skb;
 937 }
 938
 939 static struct gnttab_map_grant_ref *xenvif_get_requests(struct xenvif_queue *queue,
 940                                                         struct sk_buff *skb,
 941                                                         struct xen_netif_tx_request *txp,
 942                                                         struct gnttab_map_grant_ref *gop)
 943 {
 944         struct skb_shared_info *shinfo = skb_shinfo(skb);
 945         skb_frag_t *frags = shinfo->frags;
 946         u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
 947         int start;
 948         pending_ring_idx_t index;
 949         unsigned int nr_slots, frag_overflow = 0;
 950
 951         /* At this point shinfo->nr_frags is in fact the number of
 952          * slots, which can be as large as XEN_NETBK_LEGACY_SLOTS_MAX.
 953          */
 954         if (shinfo->nr_frags > MAX_SKB_FRAGS) {
 955                 frag_overflow = shinfo->nr_frags - MAX_SKB_FRAGS;
 956                 BUG_ON(frag_overflow > MAX_SKB_FRAGS);
 957                 shinfo->nr_frags = MAX_SKB_FRAGS;
 958         }
 959         nr_slots = shinfo->nr_frags;
 960
 961         /* Skip first skb fragment if it is on same page as header fragment. */
 962         start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
 963
 964         for (shinfo->nr_frags = start; shinfo->nr_frags < nr_slots;
 965              shinfo->nr_frags++, txp++, gop++) {
 966                 index = pending_index(queue->pending_cons++);
 967                 pending_idx = queue->pending_ring[index];
 968                 xenvif_tx_create_map_op(queue, pending_idx, txp, gop);
 969                 frag_set_pending_idx(&frags[shinfo->nr_frags], pending_idx);
 970         }
 971
 972         if (frag_overflow) {
 973                 struct sk_buff *nskb = xenvif_alloc_skb(0);
 974                 if (unlikely(nskb == NULL)) {
 975                         if (net_ratelimit())
 976                                 netdev_err(queue->vif->dev,
 977                                            "Can't allocate the frag_list skb.\n");
 978                         return NULL;
 979                 }
 980
 981                 shinfo = skb_shinfo(nskb);
 982                 frags = shinfo->frags;
 983
 984                 for (shinfo->nr_frags = 0; shinfo->nr_frags < frag_overflow;
 985                      shinfo->nr_frags++, txp++, gop++) {
 986                         index = pending_index(queue->pending_cons++);
 987                         pending_idx = queue->pending_ring[index];
 988                         xenvif_tx_create_map_op(queue, pending_idx, txp, gop);
 989                         frag_set_pending_idx(&frags[shinfo->nr_frags],
 990                                              pending_idx);
 991                 }
 992
 993                 skb_shinfo(skb)->frag_list = nskb;
 994         }
 995
 996         return gop;
 997 }
 998
 999 static inline void xenvif_grant_handle_set(struct xenvif_queue *queue,
1000                                            u16 pending_idx,
1001                                            grant_handle_t handle)
1002 {
1003         if (unlikely(queue->grant_tx_handle[pending_idx] !=
1004                      NETBACK_INVALID_HANDLE)) {
1005                 netdev_err(queue->vif->dev,
1006                            "Trying to overwrite active handle! pending_idx: %x\n",
1007                            pending_idx);
1008                 BUG();
1009         }
1010         queue->grant_tx_handle[pending_idx] = handle;
1011 }
1012
1013 static inline void xenvif_grant_handle_reset(struct xenvif_queue *queue,
1014                                              u16 pending_idx)
1015 {
1016         if (unlikely(queue->grant_tx_handle[pending_idx] ==
1017                      NETBACK_INVALID_HANDLE)) {
1018                 netdev_err(queue->vif->dev,
1019                            "Trying to unmap invalid handle! pending_idx: %x\n",
1020                            pending_idx);
1021                 BUG();
1022         }
1023         queue->grant_tx_handle[pending_idx] = NETBACK_INVALID_HANDLE;
1024 }
1025
1026 static int xenvif_tx_check_gop(struct xenvif_queue *queue,
1027                                struct sk_buff *skb,
1028                                struct gnttab_map_grant_ref **gopp_map,
1029                                struct gnttab_copy **gopp_copy)
1030 {
1031         struct gnttab_map_grant_ref *gop_map = *gopp_map;
1032         u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
1033         /* This always points to the shinfo of the skb being checked, which
1034          * could be either the first or the one on the frag_list
1035          */
1036         struct skb_shared_info *shinfo = skb_shinfo(skb);
1037         /* If this is non-NULL, we are currently checking the frag_list skb, and
1038          * this points to the shinfo of the first one
1039          */
1040         struct skb_shared_info *first_shinfo = NULL;
1041         int nr_frags = shinfo->nr_frags;
1042         const bool sharedslot = nr_frags &&
1043                                 frag_get_pending_idx(&shinfo->frags[0]) == pending_idx;
1044         int i, err;
1045
1046         /* Check status of header. */
1047         err = (*gopp_copy)->status;
1048         if (unlikely(err)) {
1049                 if (net_ratelimit())
1050                         netdev_dbg(queue->vif->dev,
1051                                    "Grant copy of header failed! status: %d pending_idx: %u ref: %u\n",
1052                                    (*gopp_copy)->status,
1053                                    pending_idx,
1054                                    (*gopp_copy)->source.u.ref);
1055                 /* The first frag might still have this slot mapped */
1056                 if (!sharedslot)
1057                         xenvif_idx_release(queue, pending_idx,
1058                                            XEN_NETIF_RSP_ERROR);
1059         }
1060         (*gopp_copy)++;
1061
1062 check_frags:
1063         for (i = 0; i < nr_frags; i++, gop_map++) {
1064                 int j, newerr;
1065
1066                 pending_idx = frag_get_pending_idx(&shinfo->frags[i]);
1067
1068                 /* Check error status: if okay then remember grant handle. */
1069                 newerr = gop_map->status;
1070
1071                 if (likely(!newerr)) {
1072                         xenvif_grant_handle_set(queue,
1073                                                 pending_idx,
1074                                                 gop_map->handle);
1075                         /* Had a previous error? Invalidate this fragment. */
1076                         if (unlikely(err)) {
1077                                 xenvif_idx_unmap(queue, pending_idx);
1078                                 /* If the mapping of the first frag was OK, but
1079                                  * the header's copy failed, and they are
1080                                  * sharing a slot, send an error
1081                                  */
1082                                 if (i == 0 && sharedslot)
1083                                         xenvif_idx_release(queue, pending_idx,
1084                                                            XEN_NETIF_RSP_ERROR);
1085                                 else
1086                                         xenvif_idx_release(queue, pending_idx,
1087                                                            XEN_NETIF_RSP_OKAY);
1088                         }
1089                         continue;
1090                 }
1091
1092                 /* Error on this fragment: respond to client with an error. */
1093                 if (net_ratelimit())
1094                         netdev_dbg(queue->vif->dev,
1095                                    "Grant map of %d. frag failed! status: %d pending_idx: %u ref: %u\n",
1096                                    i,
1097                                    gop_map->status,
1098                                    pending_idx,
1099                                    gop_map->ref);
1100
1101                 xenvif_idx_release(queue, pending_idx, XEN_NETIF_RSP_ERROR);
1102
1103                 /* Not the first error? Preceding frags already invalidated. */
1104                 if (err)
1105                         continue;
1106
1107                 /* First error: if the header haven't shared a slot with the
1108                  * first frag, release it as well.
1109                  */
1110                 if (!sharedslot)
1111                         xenvif_idx_release(queue,
1112                                            XENVIF_TX_CB(skb)->pending_idx,
1113                                            XEN_NETIF_RSP_OKAY);
1114
1115                 /* Invalidate preceding fragments of this skb. */
1116                 for (j = 0; j < i; j++) {
1117                         pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
1118                         xenvif_idx_unmap(queue, pending_idx);
1119                         xenvif_idx_release(queue, pending_idx,
1120                                            XEN_NETIF_RSP_OKAY);
1121                 }
1122
1123                 /* And if we found the error while checking the frag_list, unmap
1124                  * the first skb's frags
1125                  */
1126                 if (first_shinfo) {
1127                         for (j = 0; j < first_shinfo->nr_frags; j++) {
1128                                 pending_idx = frag_get_pending_idx(&first_shinfo->frags[j]);
1129                                 xenvif_idx_unmap(queue, pending_idx);
1130                                 xenvif_idx_release(queue, pending_idx,
1131                                                    XEN_NETIF_RSP_OKAY);
1132                         }
1133                 }
1134
1135                 /* Remember the error: invalidate all subsequent fragments. */
1136                 err = newerr;
1137         }
1138
1139         if (skb_has_frag_list(skb) && !first_shinfo) {
1140                 first_shinfo = skb_shinfo(skb);
1141                 shinfo = skb_shinfo(skb_shinfo(skb)->frag_list);
1142                 nr_frags = shinfo->nr_frags;
1143
1144                 goto check_frags;
1145         }
1146
1147         *gopp_map = gop_map;
1148         return err;
1149 }
1150
1151 static void xenvif_fill_frags(struct xenvif_queue *queue, struct sk_buff *skb)
1152 {
1153         struct skb_shared_info *shinfo = skb_shinfo(skb);
1154         int nr_frags = shinfo->nr_frags;
1155         int i;
1156         u16 prev_pending_idx = INVALID_PENDING_IDX;
1157
1158         for (i = 0; i < nr_frags; i++) {
1159                 skb_frag_t *frag = shinfo->frags + i;
1160                 struct xen_netif_tx_request *txp;
1161                 struct page *page;
1162                 u16 pending_idx;
1163
1164                 pending_idx = frag_get_pending_idx(frag);
1165
1166                 /* If this is not the first frag, chain it to the previous*/
1167                 if (prev_pending_idx == INVALID_PENDING_IDX)
1168                         skb_shinfo(skb)->destructor_arg =
1169                                 &callback_param(queue, pending_idx);
1170                 else
1171                         callback_param(queue, prev_pending_idx).ctx =
1172                                 &callback_param(queue, pending_idx);
1173
1174                 callback_param(queue, pending_idx).ctx = NULL;
1175                 prev_pending_idx = pending_idx;
1176
1177                 txp = &queue->pending_tx_info[pending_idx].req;
1178                 page = virt_to_page(idx_to_kaddr(queue, pending_idx));
1179                 __skb_fill_page_desc(skb, i, page, txp->offset, txp->size);
1180                 skb->len += txp->size;
1181                 skb->data_len += txp->size;
1182                 skb->truesize += txp->size;
1183
1184                 /* Take an extra reference to offset network stack's put_page */
1185                 get_page(queue->mmap_pages[pending_idx]);
1186         }
1187         /* FIXME: __skb_fill_page_desc set this to true because page->pfmemalloc
1188          * overlaps with "index", and "mapping" is not set. I think mapping
1189          * should be set. If delivered to local stack, it would drop this
1190          * skb in sk_filter unless the socket has the right to use it.
1191          */
1192         skb->pfmemalloc = false;
1193 }
1194
1195 static int xenvif_get_extras(struct xenvif_queue *queue,
1196                                 struct xen_netif_extra_info *extras,
1197                                 int work_to_do)
1198 {
1199         struct xen_netif_extra_info extra;
1200         RING_IDX cons = queue->tx.req_cons;
1201
1202         do {
1203                 if (unlikely(work_to_do-- <= 0)) {
1204                         netdev_err(queue->vif->dev, "Missing extra info\n");
1205                         xenvif_fatal_tx_err(queue->vif);
1206                         return -EBADR;
1207                 }
1208
1209                 memcpy(&extra, RING_GET_REQUEST(&queue->tx, cons),
1210                        sizeof(extra));
1211                 if (unlikely(!extra.type ||
1212                              extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
1213                         queue->tx.req_cons = ++cons;
1214                         netdev_err(queue->vif->dev,
1215                                    "Invalid extra type: %d\n", extra.type);
1216                         xenvif_fatal_tx_err(queue->vif);
1217                         return -EINVAL;
1218                 }
1219
1220                 memcpy(&extras[extra.type - 1], &extra, sizeof(extra));
1221                 queue->tx.req_cons = ++cons;
1222         } while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE);
1223
1224         return work_to_do;
1225 }
1226
1227 static int xenvif_set_skb_gso(struct xenvif *vif,
1228                               struct sk_buff *skb,
1229                               struct xen_netif_extra_info *gso)
1230 {
1231         if (!gso->u.gso.size) {
1232                 netdev_err(vif->dev, "GSO size must not be zero.\n");
1233                 xenvif_fatal_tx_err(vif);
1234                 return -EINVAL;
1235         }
1236
1237         switch (gso->u.gso.type) {
1238         case XEN_NETIF_GSO_TYPE_TCPV4:
1239                 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
1240                 break;
1241         case XEN_NETIF_GSO_TYPE_TCPV6:
1242                 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
1243                 break;
1244         default:
1245                 netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
1246                 xenvif_fatal_tx_err(vif);
1247                 return -EINVAL;
1248         }
1249
1250         skb_shinfo(skb)->gso_size = gso->u.gso.size;
1251         /* gso_segs will be calculated later */
1252
1253         return 0;
1254 }
1255
1256 static int checksum_setup(struct xenvif_queue *queue, struct sk_buff *skb)
1257 {
1258         bool recalculate_partial_csum = false;
1259
1260         /* A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
1261          * peers can fail to set NETRXF_csum_blank when sending a GSO
1262          * frame. In this case force the SKB to CHECKSUM_PARTIAL and
1263          * recalculate the partial checksum.
1264          */
1265         if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
1266                 queue->stats.rx_gso_checksum_fixup++;
1267                 skb->ip_summed = CHECKSUM_PARTIAL;
1268                 recalculate_partial_csum = true;
1269         }
1270
1271         /* A non-CHECKSUM_PARTIAL SKB does not require setup. */
1272         if (skb->ip_summed != CHECKSUM_PARTIAL)
1273                 return 0;
1274
1275         return skb_checksum_setup(skb, recalculate_partial_csum);
1276 }
1277
1278 static bool tx_credit_exceeded(struct xenvif_queue *queue, unsigned size)
1279 {
1280         u64 now = get_jiffies_64();
1281         u64 next_credit = queue->credit_window_start +
1282                 msecs_to_jiffies(queue->credit_usec / 1000);
1283
1284         /* Timer could already be pending in rare cases. */
1285         if (timer_pending(&queue->credit_timeout))
1286                 return true;
1287
1288         /* Passed the point where we can replenish credit? */
1289         if (time_after_eq64(now, next_credit)) {
1290                 queue->credit_window_start = now;
1291                 tx_add_credit(queue);
1292         }
1293
1294         /* Still too big to send right now? Set a callback. */
1295         if (size > queue->remaining_credit) {
1296                 queue->credit_timeout.data     =
1297                         (unsigned long)queue;
1298                 queue->credit_timeout.function =
1299                         tx_credit_callback;
1300                 mod_timer(&queue->credit_timeout,
1301                           next_credit);
1302                 queue->credit_window_start = next_credit;
1303
1304                 return true;
1305         }
1306
1307         return false;
1308 }
1309
1310 static void xenvif_tx_build_gops(struct xenvif_queue *queue,
1311                                      int budget,
1312                                      unsigned *copy_ops,
1313                                      unsigned *map_ops)
1314 {
1315         struct gnttab_map_grant_ref *gop = queue->tx_map_ops, *request_gop;
1316         struct sk_buff *skb;
1317         int ret;
1318
1319         while (skb_queue_len(&queue->tx_queue) < budget) {
1320                 struct xen_netif_tx_request txreq;
1321                 struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX];
1322                 struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
1323                 u16 pending_idx;
1324                 RING_IDX idx;
1325                 int work_to_do;
1326                 unsigned int data_len;
1327                 pending_ring_idx_t index;
1328
1329                 if (queue->tx.sring->req_prod - queue->tx.req_cons >
1330                     XEN_NETIF_TX_RING_SIZE) {
1331                         netdev_err(queue->vif->dev,
1332                                    "Impossible number of requests. "
1333                                    "req_prod %d, req_cons %d, size %ld\n",
1334                                    queue->tx.sring->req_prod, queue->tx.req_cons,
1335                                    XEN_NETIF_TX_RING_SIZE);
1336                         xenvif_fatal_tx_err(queue->vif);
1337                         break;
1338                 }
1339
1340                 work_to_do = RING_HAS_UNCONSUMED_REQUESTS(&queue->tx);
1341                 if (!work_to_do)
1342                         break;
1343
1344                 idx = queue->tx.req_cons;
1345                 rmb(); /* Ensure that we see the request before we copy it. */
1346                 memcpy(&txreq, RING_GET_REQUEST(&queue->tx, idx), sizeof(txreq));
1347
1348                 /* Credit-based scheduling. */
1349                 if (txreq.size > queue->remaining_credit &&
1350                     tx_credit_exceeded(queue, txreq.size))
1351                         break;
1352
1353                 queue->remaining_credit -= txreq.size;
1354
1355                 work_to_do--;
1356                 queue->tx.req_cons = ++idx;
1357
1358                 memset(extras, 0, sizeof(extras));
1359                 if (txreq.flags & XEN_NETTXF_extra_info) {
1360                         work_to_do = xenvif_get_extras(queue, extras,
1361                                                        work_to_do);
1362                         idx = queue->tx.req_cons;
1363                         if (unlikely(work_to_do < 0))
1364                                 break;
1365                 }
1366
1367                 ret = xenvif_count_requests(queue, &txreq, txfrags, work_to_do);
1368                 if (unlikely(ret < 0))
1369                         break;
1370
1371                 idx += ret;
1372
1373                 if (unlikely(txreq.size < ETH_HLEN)) {
1374                         netdev_dbg(queue->vif->dev,
1375                                    "Bad packet size: %d\n", txreq.size);
1376                         xenvif_tx_err(queue, &txreq, idx);
1377                         break;
1378                 }
1379
1380                 /* No crossing a page as the payload mustn't fragment. */
1381                 if (unlikely((txreq.offset + txreq.size) > PAGE_SIZE)) {
1382                         netdev_err(queue->vif->dev,
1383                                    "txreq.offset: %x, size: %u, end: %lu\n",
1384                                    txreq.offset, txreq.size,
1385                                    (txreq.offset&~PAGE_MASK) + txreq.size);
1386                         xenvif_fatal_tx_err(queue->vif);
1387                         break;
1388                 }
1389
1390                 index = pending_index(queue->pending_cons);
1391                 pending_idx = queue->pending_ring[index];
1392
1393                 data_len = (txreq.size > PKT_PROT_LEN &&
1394                             ret < XEN_NETBK_LEGACY_SLOTS_MAX) ?
1395                         PKT_PROT_LEN : txreq.size;
1396
1397                 skb = xenvif_alloc_skb(data_len);
1398                 if (unlikely(skb == NULL)) {
1399                         netdev_dbg(queue->vif->dev,
1400                                    "Can't allocate a skb in start_xmit.\n");
1401                         xenvif_tx_err(queue, &txreq, idx);
1402                         break;
1403                 }
1404
1405                 if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type) {
1406                         struct xen_netif_extra_info *gso;
1407                         gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
1408
1409                         if (xenvif_set_skb_gso(queue->vif, skb, gso)) {
1410                                 /* Failure in xenvif_set_skb_gso is fatal. */
1411                                 kfree_skb(skb);
1412                                 break;
1413                         }
1414                 }
1415
1416                 XENVIF_TX_CB(skb)->pending_idx = pending_idx;
1417
1418                 __skb_put(skb, data_len);
1419                 queue->tx_copy_ops[*copy_ops].source.u.ref = txreq.gref;
1420                 queue->tx_copy_ops[*copy_ops].source.domid = queue->vif->domid;
1421                 queue->tx_copy_ops[*copy_ops].source.offset = txreq.offset;
1422
1423                 queue->tx_copy_ops[*copy_ops].dest.u.gmfn =
1424                         virt_to_mfn(skb->data);
1425                 queue->tx_copy_ops[*copy_ops].dest.domid = DOMID_SELF;
1426                 queue->tx_copy_ops[*copy_ops].dest.offset =
1427                         offset_in_page(skb->data);
1428
1429                 queue->tx_copy_ops[*copy_ops].len = data_len;
1430                 queue->tx_copy_ops[*copy_ops].flags = GNTCOPY_source_gref;
1431
1432                 (*copy_ops)++;
1433
1434                 skb_shinfo(skb)->nr_frags = ret;
1435                 if (data_len < txreq.size) {
1436                         skb_shinfo(skb)->nr_frags++;
1437                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1438                                              pending_idx);
1439                         xenvif_tx_create_map_op(queue, pending_idx, &txreq, gop);
1440                         gop++;
1441                 } else {
1442                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1443                                              INVALID_PENDING_IDX);
1444                         memcpy(&queue->pending_tx_info[pending_idx].req, &txreq,
1445                                sizeof(txreq));
1446                 }
1447
1448                 queue->pending_cons++;
1449
1450                 request_gop = xenvif_get_requests(queue, skb, txfrags, gop);
1451                 if (request_gop == NULL) {
1452                         kfree_skb(skb);
1453                         xenvif_tx_err(queue, &txreq, idx);
1454                         break;
1455                 }
1456                 gop = request_gop;
1457
1458                 __skb_queue_tail(&queue->tx_queue, skb);
1459
1460                 queue->tx.req_cons = idx;
1461
1462                 if (((gop-queue->tx_map_ops) >= ARRAY_SIZE(queue->tx_map_ops)) ||
1463                     (*copy_ops >= ARRAY_SIZE(queue->tx_copy_ops)))
1464                         break;
1465         }
1466
1467         (*map_ops) = gop - queue->tx_map_ops;
1468         return;
1469 }
1470
1471 /* Consolidate skb with a frag_list into a brand new one with local pages on
1472  * frags. Returns 0 or -ENOMEM if can't allocate new pages.
1473  */
1474 static int xenvif_handle_frag_list(struct xenvif_queue *queue, struct sk_buff *skb)
1475 {
1476         unsigned int offset = skb_headlen(skb);
1477         skb_frag_t frags[MAX_SKB_FRAGS];
1478         int i;
1479         struct ubuf_info *uarg;
1480         struct sk_buff *nskb = skb_shinfo(skb)->frag_list;
1481
1482         queue->stats.tx_zerocopy_sent += 2;
1483         queue->stats.tx_frag_overflow++;
1484
1485         xenvif_fill_frags(queue, nskb);
1486         /* Subtract frags size, we will correct it later */
1487         skb->truesize -= skb->data_len;
1488         skb->len += nskb->len;
1489         skb->data_len += nskb->len;
1490
1491         /* create a brand new frags array and coalesce there */
1492         for (i = 0; offset < skb->len; i++) {
1493                 struct page *page;
1494                 unsigned int len;
1495
1496                 BUG_ON(i >= MAX_SKB_FRAGS);
1497                 page = alloc_page(GFP_ATOMIC|__GFP_COLD);
1498                 if (!page) {
1499                         int j;
1500                         skb->truesize += skb->data_len;
1501                         for (j = 0; j < i; j++)
1502                                 put_page(frags[j].page.p);
1503                         return -ENOMEM;
1504                 }
1505
1506                 if (offset + PAGE_SIZE < skb->len)
1507                         len = PAGE_SIZE;
1508                 else
1509                         len = skb->len - offset;
1510                 if (skb_copy_bits(skb, offset, page_address(page), len))
1511                         BUG();
1512
1513                 offset += len;
1514                 frags[i].page.p = page;
1515                 frags[i].page_offset = 0;
1516                 skb_frag_size_set(&frags[i], len);
1517         }
1518         /* swap out with old one */
1519         memcpy(skb_shinfo(skb)->frags,
1520                frags,
1521                i * sizeof(skb_frag_t));
1522         skb_shinfo(skb)->nr_frags = i;
1523         skb->truesize += i * PAGE_SIZE;
1524
1525         /* remove traces of mapped pages and frag_list */
1526         skb_frag_list_init(skb);
1527         uarg = skb_shinfo(skb)->destructor_arg;
1528         uarg->callback(uarg, true);
1529         skb_shinfo(skb)->destructor_arg = NULL;
1530
1531         skb_shinfo(nskb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
1532         kfree_skb(nskb);
1533
1534         return 0;
1535 }
1536
1537 static int xenvif_tx_submit(struct xenvif_queue *queue)
1538 {
1539         struct gnttab_map_grant_ref *gop_map = queue->tx_map_ops;
1540         struct gnttab_copy *gop_copy = queue->tx_copy_ops;
1541         struct sk_buff *skb;
1542         int work_done = 0;
1543
1544         while ((skb = __skb_dequeue(&queue->tx_queue)) != NULL) {
1545                 struct xen_netif_tx_request *txp;
1546                 u16 pending_idx;
1547                 unsigned data_len;
1548
1549                 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
1550                 txp = &queue->pending_tx_info[pending_idx].req;
1551
1552                 /* Check the remap error code. */
1553                 if (unlikely(xenvif_tx_check_gop(queue, skb, &gop_map, &gop_copy))) {
1554                         /* If there was an error, xenvif_tx_check_gop is
1555                          * expected to release all the frags which were mapped,
1556                          * so kfree_skb shouldn't do it again
1557                          */
1558                         skb_shinfo(skb)->nr_frags = 0;
1559                         if (skb_has_frag_list(skb)) {
1560                                 struct sk_buff *nskb =
1561                                                 skb_shinfo(skb)->frag_list;
1562                                 skb_shinfo(nskb)->nr_frags = 0;
1563                         }
1564                         kfree_skb(skb);
1565                         continue;
1566                 }
1567
1568                 data_len = skb->len;
1569                 callback_param(queue, pending_idx).ctx = NULL;
1570                 if (data_len < txp->size) {
1571                         /* Append the packet payload as a fragment. */
1572                         txp->offset += data_len;
1573                         txp->size -= data_len;
1574                 } else {
1575                         /* Schedule a response immediately. */
1576                         xenvif_idx_release(queue, pending_idx,
1577                                            XEN_NETIF_RSP_OKAY);
1578                 }
1579
1580                 if (txp->flags & XEN_NETTXF_csum_blank)
1581                         skb->ip_summed = CHECKSUM_PARTIAL;
1582                 else if (txp->flags & XEN_NETTXF_data_validated)
1583                         skb->ip_summed = CHECKSUM_UNNECESSARY;
1584
1585                 xenvif_fill_frags(queue, skb);
1586
1587                 if (unlikely(skb_has_frag_list(skb))) {
1588                         if (xenvif_handle_frag_list(queue, skb)) {
1589                                 if (net_ratelimit())
1590                                         netdev_err(queue->vif->dev,
1591                                                    "Not enough memory to consolidate frag_list!\n");
1592                                 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
1593                                 kfree_skb(skb);
1594                                 continue;
1595                         }
1596                 }
1597
1598                 if (skb_is_nonlinear(skb) && skb_headlen(skb) < PKT_PROT_LEN) {
1599                         int target = min_t(int, skb->len, PKT_PROT_LEN);
1600                         __pskb_pull_tail(skb, target - skb_headlen(skb));
1601                 }
1602
1603                 skb->dev      = queue->vif->dev;
1604                 skb->protocol = eth_type_trans(skb, skb->dev);
1605                 skb_reset_network_header(skb);
1606
1607                 if (checksum_setup(queue, skb)) {
1608                         netdev_dbg(queue->vif->dev,
1609                                    "Can't setup checksum in net_tx_action\n");
1610                         /* We have to set this flag to trigger the callback */
1611                         if (skb_shinfo(skb)->destructor_arg)
1612                                 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
1613                         kfree_skb(skb);
1614                         continue;
1615                 }
1616
1617                 skb_probe_transport_header(skb, 0);
1618
1619                 /* If the packet is GSO then we will have just set up the
1620                  * transport header offset in checksum_setup so it's now
1621                  * straightforward to calculate gso_segs.
1622                  */
1623                 if (skb_is_gso(skb)) {
1624                         int mss = skb_shinfo(skb)->gso_size;
1625                         int hdrlen = skb_transport_header(skb) -
1626                                 skb_mac_header(skb) +
1627                                 tcp_hdrlen(skb);
1628
1629                         skb_shinfo(skb)->gso_segs =
1630                                 DIV_ROUND_UP(skb->len - hdrlen, mss);
1631                 }
1632
1633                 queue->stats.rx_bytes += skb->len;
1634                 queue->stats.rx_packets++;
1635
1636                 work_done++;
1637
1638                 /* Set this flag right before netif_receive_skb, otherwise
1639                  * someone might think this packet already left netback, and
1640                  * do a skb_copy_ubufs while we are still in control of the
1641                  * skb. E.g. the __pskb_pull_tail earlier can do such thing.
1642                  */
1643                 if (skb_shinfo(skb)->destructor_arg) {
1644                         skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
1645                         queue->stats.tx_zerocopy_sent++;
1646                 }
1647
1648                 netif_receive_skb(skb);
1649         }
1650
1651         return work_done;
1652 }
1653
1654 void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success)
1655 {
1656         unsigned long flags;
1657         pending_ring_idx_t index;
1658         struct xenvif_queue *queue = ubuf_to_queue(ubuf);
1659
1660         /* This is the only place where we grab this lock, to protect callbacks
1661          * from each other.
1662          */
1663         spin_lock_irqsave(&queue->callback_lock, flags);
1664         do {
1665                 u16 pending_idx = ubuf->desc;
1666                 ubuf = (struct ubuf_info *) ubuf->ctx;
1667                 BUG_ON(queue->dealloc_prod - queue->dealloc_cons >=
1668                         MAX_PENDING_REQS);
1669                 index = pending_index(queue->dealloc_prod);
1670                 queue->dealloc_ring[index] = pending_idx;
1671                 /* Sync with xenvif_tx_dealloc_action:
1672                  * insert idx then incr producer.
1673                  */
1674                 smp_wmb();
1675                 queue->dealloc_prod++;
1676         } while (ubuf);
1677         wake_up(&queue->dealloc_wq);
1678         spin_unlock_irqrestore(&queue->callback_lock, flags);
1679
1680         if (likely(zerocopy_success))
1681                 queue->stats.tx_zerocopy_success++;
1682         else
1683                 queue->stats.tx_zerocopy_fail++;
1684 }
1685
1686 static inline void xenvif_tx_dealloc_action(struct xenvif_queue *queue)
1687 {
1688         struct gnttab_unmap_grant_ref *gop;
1689         pending_ring_idx_t dc, dp;
1690         u16 pending_idx, pending_idx_release[MAX_PENDING_REQS];
1691         unsigned int i = 0;
1692
1693         dc = queue->dealloc_cons;
1694         gop = queue->tx_unmap_ops;
1695
1696         /* Free up any grants we have finished using */
1697         do {
1698                 dp = queue->dealloc_prod;
1699
1700                 /* Ensure we see all indices enqueued by all
1701                  * xenvif_zerocopy_callback().
1702                  */
1703                 smp_rmb();
1704
1705                 while (dc != dp) {
1706                         BUG_ON(gop - queue->tx_unmap_ops > MAX_PENDING_REQS);
1707                         pending_idx =
1708                                 queue->dealloc_ring[pending_index(dc++)];
1709
1710                         pending_idx_release[gop-queue->tx_unmap_ops] =
1711                                 pending_idx;
1712                         queue->pages_to_unmap[gop-queue->tx_unmap_ops] =
1713                                 queue->mmap_pages[pending_idx];
1714                         gnttab_set_unmap_op(gop,
1715                                             idx_to_kaddr(queue, pending_idx),
1716                                             GNTMAP_host_map,
1717                                             queue->grant_tx_handle[pending_idx]);
1718                         xenvif_grant_handle_reset(queue, pending_idx);
1719                         ++gop;
1720                 }
1721
1722         } while (dp != queue->dealloc_prod);
1723
1724         queue->dealloc_cons = dc;
1725
1726         if (gop - queue->tx_unmap_ops > 0) {
1727                 int ret;
1728                 ret = gnttab_unmap_refs(queue->tx_unmap_ops,
1729                                         NULL,
1730                                         queue->pages_to_unmap,
1731                                         gop - queue->tx_unmap_ops);
1732                 if (ret) {
1733                         netdev_err(queue->vif->dev, "Unmap fail: nr_ops %tx ret %d\n",
1734                                    gop - queue->tx_unmap_ops, ret);
1735                         for (i = 0; i < gop - queue->tx_unmap_ops; ++i) {
1736                                 if (gop[i].status != GNTST_okay)
1737                                         netdev_err(queue->vif->dev,
1738                                                    " host_addr: %llx handle: %x status: %d\n",
1739                                                    gop[i].host_addr,
1740                                                    gop[i].handle,
1741                                                    gop[i].status);
1742                         }
1743                         BUG();
1744                 }
1745         }
1746
1747         for (i = 0; i < gop - queue->tx_unmap_ops; ++i)
1748                 xenvif_idx_release(queue, pending_idx_release[i],
1749                                    XEN_NETIF_RSP_OKAY);
1750 }
1751
1752
1753 /* Called after netfront has transmitted */
1754 int xenvif_tx_action(struct xenvif_queue *queue, int budget)
1755 {
1756         unsigned nr_mops, nr_cops = 0;
1757         int work_done, ret;
1758
1759         if (unlikely(!tx_work_todo(queue)))
1760                 return 0;
1761
1762         xenvif_tx_build_gops(queue, budget, &nr_cops, &nr_mops);
1763
1764         if (nr_cops == 0)
1765                 return 0;
1766
1767         gnttab_batch_copy(queue->tx_copy_ops, nr_cops);
1768         if (nr_mops != 0) {
1769                 ret = gnttab_map_refs(queue->tx_map_ops,
1770                                       NULL,
1771                                       queue->pages_to_map,
1772                                       nr_mops);
1773                 BUG_ON(ret);
1774         }
1775
1776         work_done = xenvif_tx_submit(queue);
1777
1778         return work_done;
1779 }
1780
1781 static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
1782                                u8 status)
1783 {
1784         struct pending_tx_info *pending_tx_info;
1785         pending_ring_idx_t index;
1786         unsigned long flags;
1787
1788         pending_tx_info = &queue->pending_tx_info[pending_idx];
1789         spin_lock_irqsave(&queue->response_lock, flags);
1790         make_tx_response(queue, &pending_tx_info->req, status);
1791         index = pending_index(queue->pending_prod);
1792         queue->pending_ring[index] = pending_idx;
1793         /* TX shouldn't use the index before we give it back here */
1794         mb();
1795         queue->pending_prod++;
1796         spin_unlock_irqrestore(&queue->response_lock, flags);
1797 }
1798
1799
1800 static void make_tx_response(struct xenvif_queue *queue,
1801                              struct xen_netif_tx_request *txp,
1802                              s8       st)
1803 {
1804         RING_IDX i = queue->tx.rsp_prod_pvt;
1805         struct xen_netif_tx_response *resp;
1806         int notify;
1807
1808         resp = RING_GET_RESPONSE(&queue->tx, i);
1809         resp->id     = txp->id;
1810         resp->status = st;
1811
1812         if (txp->flags & XEN_NETTXF_extra_info)
1813                 RING_GET_RESPONSE(&queue->tx, ++i)->status = XEN_NETIF_RSP_NULL;
1814
1815         queue->tx.rsp_prod_pvt = ++i;
1816         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->tx, notify);
1817         if (notify)
1818                 notify_remote_via_irq(queue->tx_irq);
1819 }
1820
1821 static struct xen_netif_rx_response *make_rx_response(struct xenvif_queue *queue,
1822                                              u16      id,
1823                                              s8       st,
1824                                              u16      offset,
1825                                              u16      size,
1826                                              u16      flags)
1827 {
1828         RING_IDX i = queue->rx.rsp_prod_pvt;
1829         struct xen_netif_rx_response *resp;
1830
1831         resp = RING_GET_RESPONSE(&queue->rx, i);
1832         resp->offset     = offset;
1833         resp->flags      = flags;
1834         resp->id         = id;
1835         resp->status     = (s16)size;
1836         if (st < 0)
1837                 resp->status = (s16)st;
1838
1839         queue->rx.rsp_prod_pvt = ++i;
1840
1841         return resp;
1842 }
1843
1844 void xenvif_idx_unmap(struct xenvif_queue *queue, u16 pending_idx)
1845 {
1846         int ret;
1847         struct gnttab_unmap_grant_ref tx_unmap_op;
1848
1849         gnttab_set_unmap_op(&tx_unmap_op,
1850                             idx_to_kaddr(queue, pending_idx),
1851                             GNTMAP_host_map,
1852                             queue->grant_tx_handle[pending_idx]);
1853         xenvif_grant_handle_reset(queue, pending_idx);
1854
1855         ret = gnttab_unmap_refs(&tx_unmap_op, NULL,
1856                                 &queue->mmap_pages[pending_idx], 1);
1857         if (ret) {
1858                 netdev_err(queue->vif->dev,
1859                            "Unmap fail: ret: %d pending_idx: %d host_addr: %llx handle: %x status: %d\n",
1860                            ret,
1861                            pending_idx,
1862                            tx_unmap_op.host_addr,
1863                            tx_unmap_op.handle,
1864                            tx_unmap_op.status);
1865                 BUG();
1866         }
1867 }
1868
1869 static inline int rx_work_todo(struct xenvif_queue *queue)
1870 {
1871         return (!skb_queue_empty(&queue->rx_queue) &&
1872                xenvif_rx_ring_slots_available(queue, queue->rx_last_skb_slots));
1873 }
1874
1875 static inline int tx_work_todo(struct xenvif_queue *queue)
1876 {
1877         if (likely(RING_HAS_UNCONSUMED_REQUESTS(&queue->tx)))
1878                 return 1;
1879
1880         return 0;
1881 }
1882
1883 static inline bool tx_dealloc_work_todo(struct xenvif_queue *queue)
1884 {
1885         return queue->dealloc_cons != queue->dealloc_prod;
1886 }
1887
1888 void xenvif_unmap_frontend_rings(struct xenvif_queue *queue)
1889 {
1890         if (queue->tx.sring)
1891                 xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(queue->vif),
1892                                         queue->tx.sring);
1893         if (queue->rx.sring)
1894                 xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(queue->vif),
1895                                         queue->rx.sring);
1896 }
1897
1898 int xenvif_map_frontend_rings(struct xenvif_queue *queue,
1899                               grant_ref_t tx_ring_ref,
1900                               grant_ref_t rx_ring_ref)
1901 {
1902         void *addr;
1903         struct xen_netif_tx_sring *txs;
1904         struct xen_netif_rx_sring *rxs;
1905
1906         int err = -ENOMEM;
1907
1908         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
1909                                      tx_ring_ref, &addr);
1910         if (err)
1911                 goto err;
1912
1913         txs = (struct xen_netif_tx_sring *)addr;
1914         BACK_RING_INIT(&queue->tx, txs, PAGE_SIZE);
1915
1916         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
1917                                      rx_ring_ref, &addr);
1918         if (err)
1919                 goto err;
1920
1921         rxs = (struct xen_netif_rx_sring *)addr;
1922         BACK_RING_INIT(&queue->rx, rxs, PAGE_SIZE);
1923
1924         return 0;
1925
1926 err:
1927         xenvif_unmap_frontend_rings(queue);
1928         return err;
1929 }
1930
1931 static void xenvif_start_queue(struct xenvif_queue *queue)
1932 {
1933         if (xenvif_schedulable(queue->vif))
1934                 xenvif_wake_queue(queue);
1935 }
1936
1937 /* Only called from the queue's thread, it handles the situation when the guest
1938  * doesn't post enough requests on the receiving ring.
1939  * First xenvif_start_xmit disables QDisc and start a timer, and then either the
1940  * timer fires, or the guest send an interrupt after posting new request. If it
1941  * is the timer, the carrier is turned off here.
1942  * */
1943 static void xenvif_rx_purge_event(struct xenvif_queue *queue)
1944 {
1945         /* Either the last unsuccesful skb or at least 1 slot should fit */
1946         int needed = queue->rx_last_skb_slots ?
1947                      queue->rx_last_skb_slots : 1;
1948
1949         /* It is assumed that if the guest post new slots after this, the RX
1950          * interrupt will set the QUEUE_STATUS_RX_PURGE_EVENT bit and wake up
1951          * the thread again
1952          */
1953         set_bit(QUEUE_STATUS_RX_STALLED, &queue->status);
1954         if (!xenvif_rx_ring_slots_available(queue, needed)) {
1955                 rtnl_lock();
1956                 if (netif_carrier_ok(queue->vif->dev)) {
1957                         /* Timer fired and there are still no slots. Turn off
1958                          * everything except the interrupts
1959                          */
1960                         netif_carrier_off(queue->vif->dev);
1961                         skb_queue_purge(&queue->rx_queue);
1962                         queue->rx_last_skb_slots = 0;
1963                         if (net_ratelimit())
1964                                 netdev_err(queue->vif->dev, "Carrier off due to lack of guest response on queue %d\n", queue->id);
1965                 } else {
1966                         /* Probably an another queue already turned the carrier
1967                          * off, make sure nothing is stucked in the internal
1968                          * queue of this queue
1969                          */
1970                         skb_queue_purge(&queue->rx_queue);
1971                         queue->rx_last_skb_slots = 0;
1972                 }
1973                 rtnl_unlock();
1974         } else if (!netif_carrier_ok(queue->vif->dev)) {
1975                 unsigned int num_queues = queue->vif->num_queues;
1976                 unsigned int i;
1977                 /* The carrier was down, but an interrupt kicked
1978                  * the thread again after new requests were
1979                  * posted
1980                  */
1981                 clear_bit(QUEUE_STATUS_RX_STALLED,
1982                           &queue->status);
1983                 rtnl_lock();
1984                 netif_carrier_on(queue->vif->dev);
1985                 netif_tx_wake_all_queues(queue->vif->dev);
1986                 rtnl_unlock();
1987
1988                 for (i = 0; i < num_queues; i++) {
1989                         struct xenvif_queue *temp = &queue->vif->queues[i];
1990
1991                         xenvif_napi_schedule_or_enable_events(temp);
1992                 }
1993                 if (net_ratelimit())
1994                         netdev_err(queue->vif->dev, "Carrier on again\n");
1995         } else {
1996                 /* Queuing were stopped, but the guest posted
1997                  * new requests and sent an interrupt
1998                  */
1999                 clear_bit(QUEUE_STATUS_RX_STALLED,
2000                           &queue->status);
2001                 del_timer_sync(&queue->rx_stalled);
2002                 xenvif_start_queue(queue);
2003         }
2004 }
2005
2006 int xenvif_kthread_guest_rx(void *data)
2007 {
2008         struct xenvif_queue *queue = data;
2009         struct sk_buff *skb;
2010
2011         while (!kthread_should_stop()) {
2012                 wait_event_interruptible(queue->wq,
2013                                          rx_work_todo(queue) ||
2014                                          queue->vif->disabled ||
2015                                          test_bit(QUEUE_STATUS_RX_PURGE_EVENT, &queue->status) ||
2016                                          kthread_should_stop());
2017
2018                 if (kthread_should_stop())
2019                         break;
2020
2021                 /* This frontend is found to be rogue, disable it in
2022                  * kthread context. Currently this is only set when
2023                  * netback finds out frontend sends malformed packet,
2024                  * but we cannot disable the interface in softirq
2025                  * context so we defer it here, if this thread is
2026                  * associated with queue 0.
2027                  */
2028                 if (unlikely(queue->vif->disabled && queue->id == 0))
2029                         xenvif_carrier_off(queue->vif);
2030                 else if (unlikely(test_and_clear_bit(QUEUE_STATUS_RX_PURGE_EVENT,
2031                                                      &queue->status))) {
2032                         xenvif_rx_purge_event(queue);
2033                 } else if (!netif_carrier_ok(queue->vif->dev)) {
2034                         /* Another queue stalled and turned the carrier off, so
2035                          * purge the internal queue of queues which were not
2036                          * blocked
2037                          */
2038                         skb_queue_purge(&queue->rx_queue);
2039                         queue->rx_last_skb_slots = 0;
2040                 }
2041
2042                 if (!skb_queue_empty(&queue->rx_queue))
2043                         xenvif_rx_action(queue);
2044
2045                 cond_resched();
2046         }
2047
2048         /* Bin any remaining skbs */
2049         while ((skb = skb_dequeue(&queue->rx_queue)) != NULL)
2050                 dev_kfree_skb(skb);
2051
2052         return 0;
2053 }
2054
2055 int xenvif_dealloc_kthread(void *data)
2056 {
2057         struct xenvif_queue *queue = data;
2058
2059         while (!kthread_should_stop()) {
2060                 wait_event_interruptible(queue->dealloc_wq,
2061                                          tx_dealloc_work_todo(queue) ||
2062                                          kthread_should_stop());
2063                 if (kthread_should_stop())
2064                         break;
2065
2066                 xenvif_tx_dealloc_action(queue);
2067                 cond_resched();
2068         }
2069
2070         /* Unmap anything remaining*/
2071         if (tx_dealloc_work_todo(queue))
2072                 xenvif_tx_dealloc_action(queue);
2073
2074         return 0;
2075 }
2076
2077 static int __init netback_init(void)
2078 {
2079         int rc = 0;
2080
2081         if (!xen_domain())
2082                 return -ENODEV;
2083
2084         /* Allow as many queues as there are CPUs, by default */
2085         xenvif_max_queues = num_online_cpus();
2086
2087         if (fatal_skb_slots < XEN_NETBK_LEGACY_SLOTS_MAX) {
2088                 pr_info("fatal_skb_slots too small (%d), bump it to XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n",
2089                         fatal_skb_slots, XEN_NETBK_LEGACY_SLOTS_MAX);
2090                 fatal_skb_slots = XEN_NETBK_LEGACY_SLOTS_MAX;
2091         }
2092
2093         rc = xenvif_xenbus_init();
2094         if (rc)
2095                 goto failed_init;
2096
2097         rx_drain_timeout_jiffies = msecs_to_jiffies(rx_drain_timeout_msecs);
2098
2099 #ifdef CONFIG_DEBUG_FS
2100         xen_netback_dbg_root = debugfs_create_dir("xen-netback", NULL);
2101         if (IS_ERR_OR_NULL(xen_netback_dbg_root))
2102                 pr_warn("Init of debugfs returned %ld!\n",
2103                         PTR_ERR(xen_netback_dbg_root));
2104 #endif /* CONFIG_DEBUG_FS */
2105
2106         return 0;
2107
2108 failed_init:
2109         return rc;
2110 }
2111
2112 module_init(netback_init);
2113
2114 static void __exit netback_fini(void)
2115 {
2116 #ifdef CONFIG_DEBUG_FS
2117         if (!IS_ERR_OR_NULL(xen_netback_dbg_root))
2118                 debugfs_remove_recursive(xen_netback_dbg_root);
2119 #endif /* CONFIG_DEBUG_FS */
2120         xenvif_xenbus_fini();
2121 }
2122 module_exit(netback_fini);
2123
2124 MODULE_LICENSE("Dual BSD/GPL");
2125 MODULE_ALIAS("xen-backend:vif");