1 /* 2 * Copyright (c) 2018 Citrix Systems Inc. 3 * (c) Gerd Hoffmann <kraxel@redhat.com> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; under version 2 of the License. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License along 15 * with this program; if not, see <http://www.gnu.org/licenses/>. 16 * 17 * Contributions after 2012-01-13 are licensed under the terms of the 18 * GNU GPL, version 2 or (at your option) any later version. 19 */ 20 21 #include "qemu/osdep.h" 22 #include "qemu/error-report.h" 23 #include "qemu/main-loop.h" 24 #include "qapi/error.h" 25 #include "hw/xen/xen_common.h" 26 #include "hw/block/xen_blkif.h" 27 #include "sysemu/block-backend.h" 28 #include "sysemu/iothread.h" 29 #include "xen-block.h" 30 31 typedef struct XenBlockRequest { 32 blkif_request_t req; 33 int16_t status; 34 off_t start; 35 QEMUIOVector v; 36 void *buf; 37 size_t size; 38 int presync; 39 int aio_inflight; 40 int aio_errors; 41 XenBlockDataPlane *dataplane; 42 QLIST_ENTRY(XenBlockRequest) list; 43 BlockAcctCookie acct; 44 } XenBlockRequest; 45 46 struct XenBlockDataPlane { 47 XenDevice *xendev; 48 XenEventChannel *event_channel; 49 unsigned int *ring_ref; 50 unsigned int nr_ring_ref; 51 void *sring; 52 int protocol; 53 blkif_back_rings_t rings; 54 int more_work; 55 QLIST_HEAD(inflight_head, XenBlockRequest) inflight; 56 QLIST_HEAD(freelist_head, XenBlockRequest) freelist; 57 int requests_total; 58 int requests_inflight; 59 unsigned int max_requests; 60 BlockBackend *blk; 61 unsigned int sector_size; 62 QEMUBH *bh; 63 IOThread *iothread; 64 AioContext *ctx; 65 }; 66 67 static void reset_request(XenBlockRequest *request) 68 { 69 memset(&request->req, 0, sizeof(request->req)); 70 request->status = 0; 71 request->start = 0; 72 request->size = 0; 73 request->presync = 0; 74 75 request->aio_inflight = 0; 76 request->aio_errors = 0; 77 78 request->dataplane = NULL; 79 memset(&request->list, 0, sizeof(request->list)); 80 memset(&request->acct, 0, sizeof(request->acct)); 81 82 qemu_iovec_reset(&request->v); 83 } 84 85 static XenBlockRequest *xen_block_start_request(XenBlockDataPlane *dataplane) 86 { 87 XenBlockRequest *request = NULL; 88 89 if (QLIST_EMPTY(&dataplane->freelist)) { 90 if (dataplane->requests_total >= dataplane->max_requests) { 91 goto out; 92 } 93 /* allocate new struct */ 94 request = g_malloc0(sizeof(*request)); 95 request->dataplane = dataplane; 96 /* 97 * We cannot need more pages per requests than this, and since we 98 * re-use requests, allocate the memory once here. It will be freed 99 * xen_block_dataplane_destroy() when the request list is freed. 100 */ 101 request->buf = qemu_memalign(XC_PAGE_SIZE, 102 BLKIF_MAX_SEGMENTS_PER_REQUEST * 103 XC_PAGE_SIZE); 104 dataplane->requests_total++; 105 qemu_iovec_init(&request->v, 1); 106 } else { 107 /* get one from freelist */ 108 request = QLIST_FIRST(&dataplane->freelist); 109 QLIST_REMOVE(request, list); 110 } 111 QLIST_INSERT_HEAD(&dataplane->inflight, request, list); 112 dataplane->requests_inflight++; 113 114 out: 115 return request; 116 } 117 118 static void xen_block_finish_request(XenBlockRequest *request) 119 { 120 XenBlockDataPlane *dataplane = request->dataplane; 121 122 QLIST_REMOVE(request, list); 123 dataplane->requests_inflight--; 124 } 125 126 static void xen_block_release_request(XenBlockRequest *request) 127 { 128 XenBlockDataPlane *dataplane = request->dataplane; 129 130 QLIST_REMOVE(request, list); 131 reset_request(request); 132 request->dataplane = dataplane; 133 QLIST_INSERT_HEAD(&dataplane->freelist, request, list); 134 dataplane->requests_inflight--; 135 } 136 137 /* 138 * translate request into iovec + start offset 139 * do sanity checks along the way 140 */ 141 static int xen_block_parse_request(XenBlockRequest *request) 142 { 143 XenBlockDataPlane *dataplane = request->dataplane; 144 size_t len; 145 int i; 146 147 switch (request->req.operation) { 148 case BLKIF_OP_READ: 149 break; 150 case BLKIF_OP_FLUSH_DISKCACHE: 151 request->presync = 1; 152 if (!request->req.nr_segments) { 153 return 0; 154 } 155 /* fall through */ 156 case BLKIF_OP_WRITE: 157 break; 158 case BLKIF_OP_DISCARD: 159 return 0; 160 default: 161 error_report("error: unknown operation (%d)", request->req.operation); 162 goto err; 163 }; 164 165 if (request->req.operation != BLKIF_OP_READ && 166 blk_is_read_only(dataplane->blk)) { 167 error_report("error: write req for ro device"); 168 goto err; 169 } 170 171 request->start = request->req.sector_number * dataplane->sector_size; 172 for (i = 0; i < request->req.nr_segments; i++) { 173 if (i == BLKIF_MAX_SEGMENTS_PER_REQUEST) { 174 error_report("error: nr_segments too big"); 175 goto err; 176 } 177 if (request->req.seg[i].first_sect > request->req.seg[i].last_sect) { 178 error_report("error: first > last sector"); 179 goto err; 180 } 181 if (request->req.seg[i].last_sect * dataplane->sector_size >= 182 XC_PAGE_SIZE) { 183 error_report("error: page crossing"); 184 goto err; 185 } 186 187 len = (request->req.seg[i].last_sect - 188 request->req.seg[i].first_sect + 1) * dataplane->sector_size; 189 request->size += len; 190 } 191 if (request->start + request->size > blk_getlength(dataplane->blk)) { 192 error_report("error: access beyond end of file"); 193 goto err; 194 } 195 return 0; 196 197 err: 198 request->status = BLKIF_RSP_ERROR; 199 return -1; 200 } 201 202 static int xen_block_copy_request(XenBlockRequest *request) 203 { 204 XenBlockDataPlane *dataplane = request->dataplane; 205 XenDevice *xendev = dataplane->xendev; 206 XenDeviceGrantCopySegment segs[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 207 int i, count; 208 bool to_domain = (request->req.operation == BLKIF_OP_READ); 209 void *virt = request->buf; 210 Error *local_err = NULL; 211 212 if (request->req.nr_segments == 0) { 213 return 0; 214 } 215 216 count = request->req.nr_segments; 217 218 for (i = 0; i < count; i++) { 219 if (to_domain) { 220 segs[i].dest.foreign.ref = request->req.seg[i].gref; 221 segs[i].dest.foreign.offset = request->req.seg[i].first_sect * 222 dataplane->sector_size; 223 segs[i].source.virt = virt; 224 } else { 225 segs[i].source.foreign.ref = request->req.seg[i].gref; 226 segs[i].source.foreign.offset = request->req.seg[i].first_sect * 227 dataplane->sector_size; 228 segs[i].dest.virt = virt; 229 } 230 segs[i].len = (request->req.seg[i].last_sect - 231 request->req.seg[i].first_sect + 1) * 232 dataplane->sector_size; 233 virt += segs[i].len; 234 } 235 236 xen_device_copy_grant_refs(xendev, to_domain, segs, count, &local_err); 237 238 if (local_err) { 239 error_reportf_err(local_err, "failed to copy data: "); 240 241 request->aio_errors++; 242 return -1; 243 } 244 245 return 0; 246 } 247 248 static int xen_block_do_aio(XenBlockRequest *request); 249 static int xen_block_send_response(XenBlockRequest *request); 250 251 static void xen_block_complete_aio(void *opaque, int ret) 252 { 253 XenBlockRequest *request = opaque; 254 XenBlockDataPlane *dataplane = request->dataplane; 255 256 aio_context_acquire(dataplane->ctx); 257 258 if (ret != 0) { 259 error_report("%s I/O error", 260 request->req.operation == BLKIF_OP_READ ? 261 "read" : "write"); 262 request->aio_errors++; 263 } 264 265 request->aio_inflight--; 266 if (request->presync) { 267 request->presync = 0; 268 xen_block_do_aio(request); 269 goto done; 270 } 271 if (request->aio_inflight > 0) { 272 goto done; 273 } 274 275 switch (request->req.operation) { 276 case BLKIF_OP_READ: 277 /* in case of failure request->aio_errors is increased */ 278 if (ret == 0) { 279 xen_block_copy_request(request); 280 } 281 break; 282 case BLKIF_OP_WRITE: 283 case BLKIF_OP_FLUSH_DISKCACHE: 284 default: 285 break; 286 } 287 288 request->status = request->aio_errors ? BLKIF_RSP_ERROR : BLKIF_RSP_OKAY; 289 xen_block_finish_request(request); 290 291 switch (request->req.operation) { 292 case BLKIF_OP_WRITE: 293 case BLKIF_OP_FLUSH_DISKCACHE: 294 if (!request->req.nr_segments) { 295 break; 296 } 297 /* fall through */ 298 case BLKIF_OP_READ: 299 if (request->status == BLKIF_RSP_OKAY) { 300 block_acct_done(blk_get_stats(dataplane->blk), &request->acct); 301 } else { 302 block_acct_failed(blk_get_stats(dataplane->blk), &request->acct); 303 } 304 break; 305 case BLKIF_OP_DISCARD: 306 default: 307 break; 308 } 309 if (xen_block_send_response(request)) { 310 Error *local_err = NULL; 311 312 xen_device_notify_event_channel(dataplane->xendev, 313 dataplane->event_channel, 314 &local_err); 315 if (local_err) { 316 error_report_err(local_err); 317 } 318 } 319 xen_block_release_request(request); 320 321 if (dataplane->more_work) { 322 qemu_bh_schedule(dataplane->bh); 323 } 324 325 done: 326 aio_context_release(dataplane->ctx); 327 } 328 329 static bool xen_block_split_discard(XenBlockRequest *request, 330 blkif_sector_t sector_number, 331 uint64_t nr_sectors) 332 { 333 XenBlockDataPlane *dataplane = request->dataplane; 334 int64_t byte_offset; 335 int byte_chunk; 336 uint64_t byte_remaining; 337 uint64_t sec_start = sector_number; 338 uint64_t sec_count = nr_sectors; 339 340 /* Wrap around, or overflowing byte limit? */ 341 if (sec_start + sec_count < sec_count || 342 sec_start + sec_count > INT64_MAX / dataplane->sector_size) { 343 return false; 344 } 345 346 byte_offset = sec_start * dataplane->sector_size; 347 byte_remaining = sec_count * dataplane->sector_size; 348 349 do { 350 byte_chunk = byte_remaining > BDRV_REQUEST_MAX_BYTES ? 351 BDRV_REQUEST_MAX_BYTES : byte_remaining; 352 request->aio_inflight++; 353 blk_aio_pdiscard(dataplane->blk, byte_offset, byte_chunk, 354 xen_block_complete_aio, request); 355 byte_remaining -= byte_chunk; 356 byte_offset += byte_chunk; 357 } while (byte_remaining > 0); 358 359 return true; 360 } 361 362 static int xen_block_do_aio(XenBlockRequest *request) 363 { 364 XenBlockDataPlane *dataplane = request->dataplane; 365 366 if (request->req.nr_segments && 367 (request->req.operation == BLKIF_OP_WRITE || 368 request->req.operation == BLKIF_OP_FLUSH_DISKCACHE) && 369 xen_block_copy_request(request)) { 370 goto err; 371 } 372 373 request->aio_inflight++; 374 if (request->presync) { 375 blk_aio_flush(request->dataplane->blk, xen_block_complete_aio, 376 request); 377 return 0; 378 } 379 380 switch (request->req.operation) { 381 case BLKIF_OP_READ: 382 qemu_iovec_add(&request->v, request->buf, request->size); 383 block_acct_start(blk_get_stats(dataplane->blk), &request->acct, 384 request->v.size, BLOCK_ACCT_READ); 385 request->aio_inflight++; 386 blk_aio_preadv(dataplane->blk, request->start, &request->v, 0, 387 xen_block_complete_aio, request); 388 break; 389 case BLKIF_OP_WRITE: 390 case BLKIF_OP_FLUSH_DISKCACHE: 391 if (!request->req.nr_segments) { 392 break; 393 } 394 395 qemu_iovec_add(&request->v, request->buf, request->size); 396 block_acct_start(blk_get_stats(dataplane->blk), &request->acct, 397 request->v.size, 398 request->req.operation == BLKIF_OP_WRITE ? 399 BLOCK_ACCT_WRITE : BLOCK_ACCT_FLUSH); 400 request->aio_inflight++; 401 blk_aio_pwritev(dataplane->blk, request->start, &request->v, 0, 402 xen_block_complete_aio, request); 403 break; 404 case BLKIF_OP_DISCARD: 405 { 406 struct blkif_request_discard *req = (void *)&request->req; 407 if (!xen_block_split_discard(request, req->sector_number, 408 req->nr_sectors)) { 409 goto err; 410 } 411 break; 412 } 413 default: 414 /* unknown operation (shouldn't happen -- parse catches this) */ 415 goto err; 416 } 417 418 xen_block_complete_aio(request, 0); 419 420 return 0; 421 422 err: 423 xen_block_finish_request(request); 424 request->status = BLKIF_RSP_ERROR; 425 return -1; 426 } 427 428 static int xen_block_send_response(XenBlockRequest *request) 429 { 430 XenBlockDataPlane *dataplane = request->dataplane; 431 int send_notify = 0; 432 int have_requests = 0; 433 blkif_response_t *resp; 434 435 /* Place on the response ring for the relevant domain. */ 436 switch (dataplane->protocol) { 437 case BLKIF_PROTOCOL_NATIVE: 438 resp = (blkif_response_t *)RING_GET_RESPONSE( 439 &dataplane->rings.native, 440 dataplane->rings.native.rsp_prod_pvt); 441 break; 442 case BLKIF_PROTOCOL_X86_32: 443 resp = (blkif_response_t *)RING_GET_RESPONSE( 444 &dataplane->rings.x86_32_part, 445 dataplane->rings.x86_32_part.rsp_prod_pvt); 446 break; 447 case BLKIF_PROTOCOL_X86_64: 448 resp = (blkif_response_t *)RING_GET_RESPONSE( 449 &dataplane->rings.x86_64_part, 450 dataplane->rings.x86_64_part.rsp_prod_pvt); 451 break; 452 default: 453 return 0; 454 } 455 456 resp->id = request->req.id; 457 resp->operation = request->req.operation; 458 resp->status = request->status; 459 460 dataplane->rings.common.rsp_prod_pvt++; 461 462 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&dataplane->rings.common, 463 send_notify); 464 if (dataplane->rings.common.rsp_prod_pvt == 465 dataplane->rings.common.req_cons) { 466 /* 467 * Tail check for pending requests. Allows frontend to avoid 468 * notifications if requests are already in flight (lower 469 * overheads and promotes batching). 470 */ 471 RING_FINAL_CHECK_FOR_REQUESTS(&dataplane->rings.common, 472 have_requests); 473 } else if (RING_HAS_UNCONSUMED_REQUESTS(&dataplane->rings.common)) { 474 have_requests = 1; 475 } 476 477 if (have_requests) { 478 dataplane->more_work++; 479 } 480 return send_notify; 481 } 482 483 static int xen_block_get_request(XenBlockDataPlane *dataplane, 484 XenBlockRequest *request, RING_IDX rc) 485 { 486 switch (dataplane->protocol) { 487 case BLKIF_PROTOCOL_NATIVE: { 488 blkif_request_t *req = 489 RING_GET_REQUEST(&dataplane->rings.native, rc); 490 491 memcpy(&request->req, req, sizeof(request->req)); 492 break; 493 } 494 case BLKIF_PROTOCOL_X86_32: { 495 blkif_x86_32_request_t *req = 496 RING_GET_REQUEST(&dataplane->rings.x86_32_part, rc); 497 498 blkif_get_x86_32_req(&request->req, req); 499 break; 500 } 501 case BLKIF_PROTOCOL_X86_64: { 502 blkif_x86_64_request_t *req = 503 RING_GET_REQUEST(&dataplane->rings.x86_64_part, rc); 504 505 blkif_get_x86_64_req(&request->req, req); 506 break; 507 } 508 } 509 /* Prevent the compiler from accessing the on-ring fields instead. */ 510 barrier(); 511 return 0; 512 } 513 514 /* 515 * Threshold of in-flight requests above which we will start using 516 * blk_io_plug()/blk_io_unplug() to batch requests. 517 */ 518 #define IO_PLUG_THRESHOLD 1 519 520 static bool xen_block_handle_requests(XenBlockDataPlane *dataplane) 521 { 522 RING_IDX rc, rp; 523 XenBlockRequest *request; 524 int inflight_atstart = dataplane->requests_inflight; 525 int batched = 0; 526 bool done_something = false; 527 528 dataplane->more_work = 0; 529 530 rc = dataplane->rings.common.req_cons; 531 rp = dataplane->rings.common.sring->req_prod; 532 xen_rmb(); /* Ensure we see queued requests up to 'rp'. */ 533 534 /* 535 * If there was more than IO_PLUG_THRESHOLD requests in flight 536 * when we got here, this is an indication that there the bottleneck 537 * is below us, so it's worth beginning to batch up I/O requests 538 * rather than submitting them immediately. The maximum number 539 * of requests we're willing to batch is the number already in 540 * flight, so it can grow up to max_requests when the bottleneck 541 * is below us. 542 */ 543 if (inflight_atstart > IO_PLUG_THRESHOLD) { 544 blk_io_plug(dataplane->blk); 545 } 546 while (rc != rp) { 547 /* pull request from ring */ 548 if (RING_REQUEST_CONS_OVERFLOW(&dataplane->rings.common, rc)) { 549 break; 550 } 551 request = xen_block_start_request(dataplane); 552 if (request == NULL) { 553 dataplane->more_work++; 554 break; 555 } 556 xen_block_get_request(dataplane, request, rc); 557 dataplane->rings.common.req_cons = ++rc; 558 done_something = true; 559 560 /* parse them */ 561 if (xen_block_parse_request(request) != 0) { 562 switch (request->req.operation) { 563 case BLKIF_OP_READ: 564 block_acct_invalid(blk_get_stats(dataplane->blk), 565 BLOCK_ACCT_READ); 566 break; 567 case BLKIF_OP_WRITE: 568 block_acct_invalid(blk_get_stats(dataplane->blk), 569 BLOCK_ACCT_WRITE); 570 break; 571 case BLKIF_OP_FLUSH_DISKCACHE: 572 block_acct_invalid(blk_get_stats(dataplane->blk), 573 BLOCK_ACCT_FLUSH); 574 default: 575 break; 576 }; 577 578 if (xen_block_send_response(request)) { 579 Error *local_err = NULL; 580 581 xen_device_notify_event_channel(dataplane->xendev, 582 dataplane->event_channel, 583 &local_err); 584 if (local_err) { 585 error_report_err(local_err); 586 } 587 } 588 xen_block_release_request(request); 589 continue; 590 } 591 592 if (inflight_atstart > IO_PLUG_THRESHOLD && 593 batched >= inflight_atstart) { 594 blk_io_unplug(dataplane->blk); 595 } 596 xen_block_do_aio(request); 597 if (inflight_atstart > IO_PLUG_THRESHOLD) { 598 if (batched >= inflight_atstart) { 599 blk_io_plug(dataplane->blk); 600 batched = 0; 601 } else { 602 batched++; 603 } 604 } 605 } 606 if (inflight_atstart > IO_PLUG_THRESHOLD) { 607 blk_io_unplug(dataplane->blk); 608 } 609 610 return done_something; 611 } 612 613 static void xen_block_dataplane_bh(void *opaque) 614 { 615 XenBlockDataPlane *dataplane = opaque; 616 617 aio_context_acquire(dataplane->ctx); 618 xen_block_handle_requests(dataplane); 619 aio_context_release(dataplane->ctx); 620 } 621 622 static bool xen_block_dataplane_event(void *opaque) 623 { 624 XenBlockDataPlane *dataplane = opaque; 625 626 return xen_block_handle_requests(dataplane); 627 } 628 629 XenBlockDataPlane *xen_block_dataplane_create(XenDevice *xendev, 630 BlockBackend *blk, 631 unsigned int sector_size, 632 IOThread *iothread) 633 { 634 XenBlockDataPlane *dataplane = g_new0(XenBlockDataPlane, 1); 635 636 dataplane->xendev = xendev; 637 dataplane->blk = blk; 638 dataplane->sector_size = sector_size; 639 640 QLIST_INIT(&dataplane->inflight); 641 QLIST_INIT(&dataplane->freelist); 642 643 if (iothread) { 644 dataplane->iothread = iothread; 645 object_ref(OBJECT(dataplane->iothread)); 646 dataplane->ctx = iothread_get_aio_context(dataplane->iothread); 647 } else { 648 dataplane->ctx = qemu_get_aio_context(); 649 } 650 dataplane->bh = aio_bh_new(dataplane->ctx, xen_block_dataplane_bh, 651 dataplane); 652 653 return dataplane; 654 } 655 656 void xen_block_dataplane_destroy(XenBlockDataPlane *dataplane) 657 { 658 XenBlockRequest *request; 659 660 if (!dataplane) { 661 return; 662 } 663 664 while (!QLIST_EMPTY(&dataplane->freelist)) { 665 request = QLIST_FIRST(&dataplane->freelist); 666 QLIST_REMOVE(request, list); 667 qemu_iovec_destroy(&request->v); 668 qemu_vfree(request->buf); 669 g_free(request); 670 } 671 672 qemu_bh_delete(dataplane->bh); 673 if (dataplane->iothread) { 674 object_unref(OBJECT(dataplane->iothread)); 675 } 676 677 g_free(dataplane); 678 } 679 680 void xen_block_dataplane_stop(XenBlockDataPlane *dataplane) 681 { 682 XenDevice *xendev; 683 684 if (!dataplane) { 685 return; 686 } 687 688 aio_context_acquire(dataplane->ctx); 689 /* Xen doesn't have multiple users for nodes, so this can't fail */ 690 blk_set_aio_context(dataplane->blk, qemu_get_aio_context(), &error_abort); 691 aio_context_release(dataplane->ctx); 692 693 xendev = dataplane->xendev; 694 695 if (dataplane->event_channel) { 696 Error *local_err = NULL; 697 698 xen_device_unbind_event_channel(xendev, dataplane->event_channel, 699 &local_err); 700 dataplane->event_channel = NULL; 701 702 if (local_err) { 703 error_report_err(local_err); 704 } 705 } 706 707 if (dataplane->sring) { 708 Error *local_err = NULL; 709 710 xen_device_unmap_grant_refs(xendev, dataplane->sring, 711 dataplane->nr_ring_ref, &local_err); 712 dataplane->sring = NULL; 713 714 if (local_err) { 715 error_report_err(local_err); 716 } 717 } 718 719 g_free(dataplane->ring_ref); 720 dataplane->ring_ref = NULL; 721 } 722 723 void xen_block_dataplane_start(XenBlockDataPlane *dataplane, 724 const unsigned int ring_ref[], 725 unsigned int nr_ring_ref, 726 unsigned int event_channel, 727 unsigned int protocol, 728 Error **errp) 729 { 730 XenDevice *xendev = dataplane->xendev; 731 Error *local_err = NULL; 732 unsigned int ring_size; 733 unsigned int i; 734 735 dataplane->nr_ring_ref = nr_ring_ref; 736 dataplane->ring_ref = g_new(unsigned int, nr_ring_ref); 737 738 for (i = 0; i < nr_ring_ref; i++) { 739 dataplane->ring_ref[i] = ring_ref[i]; 740 } 741 742 dataplane->protocol = protocol; 743 744 ring_size = XC_PAGE_SIZE * dataplane->nr_ring_ref; 745 switch (dataplane->protocol) { 746 case BLKIF_PROTOCOL_NATIVE: 747 { 748 dataplane->max_requests = __CONST_RING_SIZE(blkif, ring_size); 749 break; 750 } 751 case BLKIF_PROTOCOL_X86_32: 752 { 753 dataplane->max_requests = __CONST_RING_SIZE(blkif_x86_32, ring_size); 754 break; 755 } 756 case BLKIF_PROTOCOL_X86_64: 757 { 758 dataplane->max_requests = __CONST_RING_SIZE(blkif_x86_64, ring_size); 759 break; 760 } 761 default: 762 error_setg(errp, "unknown protocol %u", dataplane->protocol); 763 return; 764 } 765 766 xen_device_set_max_grant_refs(xendev, dataplane->nr_ring_ref, 767 &local_err); 768 if (local_err) { 769 error_propagate(errp, local_err); 770 goto stop; 771 } 772 773 dataplane->sring = xen_device_map_grant_refs(xendev, 774 dataplane->ring_ref, 775 dataplane->nr_ring_ref, 776 PROT_READ | PROT_WRITE, 777 &local_err); 778 if (local_err) { 779 error_propagate(errp, local_err); 780 goto stop; 781 } 782 783 switch (dataplane->protocol) { 784 case BLKIF_PROTOCOL_NATIVE: 785 { 786 blkif_sring_t *sring_native = dataplane->sring; 787 788 BACK_RING_INIT(&dataplane->rings.native, sring_native, ring_size); 789 break; 790 } 791 case BLKIF_PROTOCOL_X86_32: 792 { 793 blkif_x86_32_sring_t *sring_x86_32 = dataplane->sring; 794 795 BACK_RING_INIT(&dataplane->rings.x86_32_part, sring_x86_32, 796 ring_size); 797 break; 798 } 799 case BLKIF_PROTOCOL_X86_64: 800 { 801 blkif_x86_64_sring_t *sring_x86_64 = dataplane->sring; 802 803 BACK_RING_INIT(&dataplane->rings.x86_64_part, sring_x86_64, 804 ring_size); 805 break; 806 } 807 } 808 809 dataplane->event_channel = 810 xen_device_bind_event_channel(xendev, dataplane->ctx, event_channel, 811 xen_block_dataplane_event, dataplane, 812 &local_err); 813 if (local_err) { 814 error_propagate(errp, local_err); 815 goto stop; 816 } 817 818 aio_context_acquire(dataplane->ctx); 819 /* If other users keep the BlockBackend in the iothread, that's ok */ 820 blk_set_aio_context(dataplane->blk, dataplane->ctx, NULL); 821 aio_context_release(dataplane->ctx); 822 return; 823 824 stop: 825 xen_block_dataplane_stop(dataplane); 826 } 827