sys/dev/xen/blkfront/blkfront.c

   1 /*
   2  * XenBSD block device driver
   3  *
   4  * Copyright (c) 2010-2013 Spectra Logic Corporation
   5  * Copyright (c) 2009 Scott Long, Yahoo!
   6  * Copyright (c) 2009 Frank Suchomel, Citrix
   7  * Copyright (c) 2009 Doug F. Rabson, Citrix
   8  * Copyright (c) 2005 Kip Macy
   9  * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
  10  * Modifications by Mark A. Williamson are (c) Intel Research Cambridge
  11  *
  12  *
  13  * Permission is hereby granted, free of charge, to any person obtaining a copy
  14  * of this software and associated documentation files (the "Software"), to
  15  * deal in the Software without restriction, including without limitation the
  16  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  17  * sell copies of the Software, and to permit persons to whom the Software is
  18  * furnished to do so, subject to the following conditions:
  19  *
  20  * The above copyright notice and this permission notice shall be included in
  21  * all copies or substantial portions of the Software.
  22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  25  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  26  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  27  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  28  * DEALINGS IN THE SOFTWARE.
  29  */
  30
  31 #include <sys/cdefs.h>
  32 __FBSDID("$FreeBSD$");
  33
  34 #include <sys/param.h>
  35 #include <sys/systm.h>
  36 #include <sys/malloc.h>
  37 #include <sys/kernel.h>
  38 #include <vm/vm.h>
  39 #include <vm/pmap.h>
  40
  41 #include <sys/bio.h>
  42 #include <sys/bus.h>
  43 #include <sys/conf.h>
  44 #include <sys/module.h>
  45 #include <sys/sysctl.h>
  46
  47 #include <machine/bus.h>
  48 #include <sys/rman.h>
  49 #include <machine/resource.h>
  50 #include <machine/intr_machdep.h>
  51 #include <machine/vmparam.h>
  52
  53 #include <xen/xen-os.h>
  54 #include <xen/hypervisor.h>
  55 #include <xen/xen_intr.h>
  56 #include <xen/gnttab.h>
  57 #include <xen/interface/grant_table.h>
  58 #include <xen/interface/io/protocols.h>
  59 #include <xen/xenbus/xenbusvar.h>
  60
  61 #include <machine/_inttypes.h>
  62
  63 #include <geom/geom_disk.h>
  64
  65 #include <dev/xen/blkfront/block.h>
  66
  67 #include "xenbus_if.h"
  68
  69 /*--------------------------- Forward Declarations ---------------------------*/
  70 static void xbd_closing(device_t);
  71 static void xbd_startio(struct xbd_softc *sc);
  72
  73 /*---------------------------------- Macros ----------------------------------*/
  74 #if 0
  75 #define DPRINTK(fmt, args...) printf("[XEN] %s:%d: " fmt ".\n", __func__, __LINE__, ##args)
  76 #else
  77 #define DPRINTK(fmt, args...)
  78 #endif
  79
  80 #define XBD_SECTOR_SHFT         9
  81
  82 /*---------------------------- Global Static Data ----------------------------*/
  83 static MALLOC_DEFINE(M_XENBLOCKFRONT, "xbd", "Xen Block Front driver data");
  84
  85 static int xbd_enable_indirect = 1;
  86 SYSCTL_NODE(_hw, OID_AUTO, xbd, CTLFLAG_RD, 0, "xbd driver parameters");
  87 SYSCTL_INT(_hw_xbd, OID_AUTO, xbd_enable_indirect, CTLFLAG_RDTUN,
  88     &xbd_enable_indirect, 0, "Enable xbd indirect segments");
  89
  90 /*---------------------------- Command Processing ----------------------------*/
  91 static void
  92 xbd_freeze(struct xbd_softc *sc, xbd_flag_t xbd_flag)
  93 {
  94         if (xbd_flag != XBDF_NONE && (sc->xbd_flags & xbd_flag) != 0)
  95                 return;
  96
  97         sc->xbd_flags |= xbd_flag;
  98         sc->xbd_qfrozen_cnt++;
  99 }
 100
 101 static void
 102 xbd_thaw(struct xbd_softc *sc, xbd_flag_t xbd_flag)
 103 {
 104         if (xbd_flag != XBDF_NONE && (sc->xbd_flags & xbd_flag) == 0)
 105                 return;
 106
 107         if (sc->xbd_qfrozen_cnt == 0)
 108                 panic("%s: Thaw with flag 0x%x while not frozen.",
 109                     __func__, xbd_flag);
 110
 111         sc->xbd_flags &= ~xbd_flag;
 112         sc->xbd_qfrozen_cnt--;
 113 }
 114
 115 static void
 116 xbd_cm_freeze(struct xbd_softc *sc, struct xbd_command *cm, xbdc_flag_t cm_flag)
 117 {
 118         if ((cm->cm_flags & XBDCF_FROZEN) != 0)
 119                 return;
 120
 121         cm->cm_flags |= XBDCF_FROZEN|cm_flag;
 122         xbd_freeze(sc, XBDF_NONE);
 123 }
 124
 125 static void
 126 xbd_cm_thaw(struct xbd_softc *sc, struct xbd_command *cm)
 127 {
 128         if ((cm->cm_flags & XBDCF_FROZEN) == 0)
 129                 return;
 130
 131         cm->cm_flags &= ~XBDCF_FROZEN;
 132         xbd_thaw(sc, XBDF_NONE);
 133 }
 134
 135 static inline void
 136 xbd_flush_requests(struct xbd_softc *sc)
 137 {
 138         int notify;
 139
 140         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&sc->xbd_ring, notify);
 141
 142         if (notify)
 143                 xen_intr_signal(sc->xen_intr_handle);
 144 }
 145
 146 static void
 147 xbd_free_command(struct xbd_command *cm)
 148 {
 149
 150         KASSERT((cm->cm_flags & XBDCF_Q_MASK) == XBD_Q_NONE,
 151             ("Freeing command that is still on queue %d.",
 152             cm->cm_flags & XBDCF_Q_MASK));
 153
 154         cm->cm_flags = XBDCF_INITIALIZER;
 155         cm->cm_bp = NULL;
 156         cm->cm_complete = NULL;
 157         xbd_enqueue_cm(cm, XBD_Q_FREE);
 158         xbd_thaw(cm->cm_sc, XBDF_CM_SHORTAGE);
 159 }
 160
 161 static void
 162 xbd_mksegarray(bus_dma_segment_t *segs, int nsegs,
 163     grant_ref_t * gref_head, int otherend_id, int readonly,
 164     grant_ref_t * sg_ref, struct blkif_request_segment *sg)
 165 {
 166         struct blkif_request_segment *last_block_sg = sg + nsegs;
 167         vm_paddr_t buffer_ma;
 168         uint64_t fsect, lsect;
 169         int ref;
 170
 171         while (sg < last_block_sg) {
 172                 KASSERT(segs->ds_addr % (1 << XBD_SECTOR_SHFT) == 0,
 173                     ("XEN disk driver I/O must be sector aligned"));
 174                 KASSERT(segs->ds_len % (1 << XBD_SECTOR_SHFT) == 0,
 175                     ("XEN disk driver I/Os must be a multiple of "
 176                     "the sector length"));
 177                 buffer_ma = segs->ds_addr;
 178                 fsect = (buffer_ma & PAGE_MASK) >> XBD_SECTOR_SHFT;
 179                 lsect = fsect + (segs->ds_len  >> XBD_SECTOR_SHFT) - 1;
 180
 181                 KASSERT(lsect <= 7, ("XEN disk driver data cannot "
 182                     "cross a page boundary"));
 183
 184                 /* install a grant reference. */
 185                 ref = gnttab_claim_grant_reference(gref_head);
 186
 187                 /*
 188                  * GNTTAB_LIST_END == 0xffffffff, but it is private
 189                  * to gnttab.c.
 190                  */
 191                 KASSERT(ref != ~0, ("grant_reference failed"));
 192
 193                 gnttab_grant_foreign_access_ref(
 194                     ref,
 195                     otherend_id,
 196                     buffer_ma >> PAGE_SHIFT,
 197                     readonly);
 198
 199                 *sg_ref = ref;
 200                 *sg = (struct blkif_request_segment) {
 201                         .gref       = ref,
 202                         .first_sect = fsect,
 203                         .last_sect  = lsect
 204                 };
 205                 sg++;
 206                 sg_ref++;
 207                 segs++;
 208         }
 209 }
 210
 211 static void
 212 xbd_queue_cb(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
 213 {
 214         struct xbd_softc *sc;
 215         struct xbd_command *cm;
 216         int op;
 217
 218         cm = arg;
 219         sc = cm->cm_sc;
 220
 221         if (error) {
 222                 cm->cm_bp->bio_error = EIO;
 223                 biodone(cm->cm_bp);
 224                 xbd_free_command(cm);
 225                 return;
 226         }
 227
 228         KASSERT(nsegs <= sc->xbd_max_request_segments,
 229             ("Too many segments in a blkfront I/O"));
 230
 231         if (nsegs <= BLKIF_MAX_SEGMENTS_PER_REQUEST) {
 232                 blkif_request_t *ring_req;
 233
 234                 /* Fill out a blkif_request_t structure. */
 235                 ring_req = (blkif_request_t *)
 236                     RING_GET_REQUEST(&sc->xbd_ring, sc->xbd_ring.req_prod_pvt);
 237                 sc->xbd_ring.req_prod_pvt++;
 238                 ring_req->id = cm->cm_id;
 239                 ring_req->operation = cm->cm_operation;
 240                 ring_req->sector_number = cm->cm_sector_number;
 241                 ring_req->handle = (blkif_vdev_t)(uintptr_t)sc->xbd_disk;
 242                 ring_req->nr_segments = nsegs;
 243                 cm->cm_nseg = nsegs;
 244                 xbd_mksegarray(segs, nsegs, &cm->cm_gref_head,
 245                     xenbus_get_otherend_id(sc->xbd_dev),
 246                     cm->cm_operation == BLKIF_OP_WRITE,
 247                     cm->cm_sg_refs, ring_req->seg);
 248         } else {
 249                 blkif_request_indirect_t *ring_req;
 250
 251                 /* Fill out a blkif_request_indirect_t structure. */
 252                 ring_req = (blkif_request_indirect_t *)
 253                     RING_GET_REQUEST(&sc->xbd_ring, sc->xbd_ring.req_prod_pvt);
 254                 sc->xbd_ring.req_prod_pvt++;
 255                 ring_req->id = cm->cm_id;
 256                 ring_req->operation = BLKIF_OP_INDIRECT;
 257                 ring_req->indirect_op = cm->cm_operation;
 258                 ring_req->sector_number = cm->cm_sector_number;
 259                 ring_req->handle = (blkif_vdev_t)(uintptr_t)sc->xbd_disk;
 260                 ring_req->nr_segments = nsegs;
 261                 cm->cm_nseg = nsegs;
 262                 xbd_mksegarray(segs, nsegs, &cm->cm_gref_head,
 263                     xenbus_get_otherend_id(sc->xbd_dev),
 264                     cm->cm_operation == BLKIF_OP_WRITE,
 265                     cm->cm_sg_refs, cm->cm_indirectionpages);
 266                 memcpy(ring_req->indirect_grefs, &cm->cm_indirectionrefs,
 267                     sizeof(grant_ref_t) * sc->xbd_max_request_indirectpages);
 268         }
 269
 270         if (cm->cm_operation == BLKIF_OP_READ)
 271                 op = BUS_DMASYNC_PREREAD;
 272         else if (cm->cm_operation == BLKIF_OP_WRITE)
 273                 op = BUS_DMASYNC_PREWRITE;
 274         else
 275                 op = 0;
 276         bus_dmamap_sync(sc->xbd_io_dmat, cm->cm_map, op);
 277
 278         gnttab_free_grant_references(cm->cm_gref_head);
 279
 280         xbd_enqueue_cm(cm, XBD_Q_BUSY);
 281
 282         /*
 283          * If bus dma had to asynchronously call us back to dispatch
 284          * this command, we are no longer executing in the context of
 285          * xbd_startio().  Thus we cannot rely on xbd_startio()'s call to
 286          * xbd_flush_requests() to publish this command to the backend
 287          * along with any other commands that it could batch.
 288          */
 289         if ((cm->cm_flags & XBDCF_ASYNC_MAPPING) != 0)
 290                 xbd_flush_requests(sc);
 291
 292         return;
 293 }
 294
 295 static int
 296 xbd_queue_request(struct xbd_softc *sc, struct xbd_command *cm)
 297 {
 298         int error;
 299
 300         if (cm->cm_bp != NULL)
 301                 error = bus_dmamap_load_bio(sc->xbd_io_dmat, cm->cm_map,
 302                     cm->cm_bp, xbd_queue_cb, cm, 0);
 303         else
 304                 error = bus_dmamap_load(sc->xbd_io_dmat, cm->cm_map,
 305                     cm->cm_data, cm->cm_datalen, xbd_queue_cb, cm, 0);
 306         if (error == EINPROGRESS) {
 307                 /*
 308                  * Maintain queuing order by freezing the queue.  The next
 309                  * command may not require as many resources as the command
 310                  * we just attempted to map, so we can't rely on bus dma
 311                  * blocking for it too.
 312                  */
 313                 xbd_cm_freeze(sc, cm, XBDCF_ASYNC_MAPPING);
 314                 return (0);
 315         }
 316
 317         return (error);
 318 }
 319
 320 static void
 321 xbd_restart_queue_callback(void *arg)
 322 {
 323         struct xbd_softc *sc = arg;
 324
 325         mtx_lock(&sc->xbd_io_lock);
 326
 327         xbd_thaw(sc, XBDF_GNT_SHORTAGE);
 328
 329         xbd_startio(sc);
 330
 331         mtx_unlock(&sc->xbd_io_lock);
 332 }
 333
 334 static struct xbd_command *
 335 xbd_bio_command(struct xbd_softc *sc)
 336 {
 337         struct xbd_command *cm;
 338         struct bio *bp;
 339
 340         if (__predict_false(sc->xbd_state != XBD_STATE_CONNECTED))
 341                 return (NULL);
 342
 343         bp = xbd_dequeue_bio(sc);
 344         if (bp == NULL)
 345                 return (NULL);
 346
 347         if ((cm = xbd_dequeue_cm(sc, XBD_Q_FREE)) == NULL) {
 348                 xbd_freeze(sc, XBDF_CM_SHORTAGE);
 349                 xbd_requeue_bio(sc, bp);
 350                 return (NULL);
 351         }
 352
 353         if (gnttab_alloc_grant_references(sc->xbd_max_request_segments,
 354             &cm->cm_gref_head) != 0) {
 355                 gnttab_request_free_callback(&sc->xbd_callback,
 356                     xbd_restart_queue_callback, sc,
 357                     sc->xbd_max_request_segments);
 358                 xbd_freeze(sc, XBDF_GNT_SHORTAGE);
 359                 xbd_requeue_bio(sc, bp);
 360                 xbd_enqueue_cm(cm, XBD_Q_FREE);
 361                 return (NULL);
 362         }
 363
 364         cm->cm_bp = bp;
 365         cm->cm_sector_number = (blkif_sector_t)bp->bio_pblkno;
 366
 367         switch (bp->bio_cmd) {
 368         case BIO_READ:
 369                 cm->cm_operation = BLKIF_OP_READ;
 370                 break;
 371         case BIO_WRITE:
 372                 cm->cm_operation = BLKIF_OP_WRITE;
 373                 if ((bp->bio_flags & BIO_ORDERED) != 0) {
 374                         if ((sc->xbd_flags & XBDF_BARRIER) != 0) {
 375                                 cm->cm_operation = BLKIF_OP_WRITE_BARRIER;
 376                         } else {
 377                                 /*
 378                                  * Single step this command.
 379                                  */
 380                                 cm->cm_flags |= XBDCF_Q_FREEZE;
 381                                 if (xbd_queue_length(sc, XBD_Q_BUSY) != 0) {
 382                                         /*
 383                                          * Wait for in-flight requests to
 384                                          * finish.
 385                                          */
 386                                         xbd_freeze(sc, XBDF_WAIT_IDLE);
 387                                         xbd_requeue_cm(cm, XBD_Q_READY);
 388                                         return (NULL);
 389                                 }
 390                         }
 391                 }
 392                 break;
 393         case BIO_FLUSH:
 394                 if ((sc->xbd_flags & XBDF_FLUSH) != 0)
 395                         cm->cm_operation = BLKIF_OP_FLUSH_DISKCACHE;
 396                 else if ((sc->xbd_flags & XBDF_BARRIER) != 0)
 397                         cm->cm_operation = BLKIF_OP_WRITE_BARRIER;
 398                 else
 399                         panic("flush request, but no flush support available");
 400                 break;
 401         default:
 402                 panic("unknown bio command %d", bp->bio_cmd);
 403         }
 404
 405         return (cm);
 406 }
 407
 408 /*
 409  * Dequeue buffers and place them in the shared communication ring.
 410  * Return when no more requests can be accepted or all buffers have
 411  * been queued.
 412  *
 413  * Signal XEN once the ring has been filled out.
 414  */
 415 static void
 416 xbd_startio(struct xbd_softc *sc)
 417 {
 418         struct xbd_command *cm;
 419         int error, queued = 0;
 420
 421         mtx_assert(&sc->xbd_io_lock, MA_OWNED);
 422
 423         if (sc->xbd_state != XBD_STATE_CONNECTED)
 424                 return;
 425
 426         while (!RING_FULL(&sc->xbd_ring)) {
 427
 428                 if (sc->xbd_qfrozen_cnt != 0)
 429                         break;
 430
 431                 cm = xbd_dequeue_cm(sc, XBD_Q_READY);
 432
 433                 if (cm == NULL)
 434                     cm = xbd_bio_command(sc);
 435
 436                 if (cm == NULL)
 437                         break;
 438
 439                 if ((cm->cm_flags & XBDCF_Q_FREEZE) != 0) {
 440                         /*
 441                          * Single step command.  Future work is
 442                          * held off until this command completes.
 443                          */
 444                         xbd_cm_freeze(sc, cm, XBDCF_Q_FREEZE);
 445                 }
 446
 447                 if ((error = xbd_queue_request(sc, cm)) != 0) {
 448                         printf("xbd_queue_request returned %d\n", error);
 449                         break;
 450                 }
 451                 queued++;
 452         }
 453
 454         if (queued != 0)
 455                 xbd_flush_requests(sc);
 456 }
 457
 458 static void
 459 xbd_bio_complete(struct xbd_softc *sc, struct xbd_command *cm)
 460 {
 461         struct bio *bp;
 462
 463         bp = cm->cm_bp;
 464
 465         if (__predict_false(cm->cm_status != BLKIF_RSP_OKAY)) {
 466                 disk_err(bp, "disk error" , -1, 0);
 467                 printf(" status: %x\n", cm->cm_status);
 468                 bp->bio_flags |= BIO_ERROR;
 469         }
 470
 471         if (bp->bio_flags & BIO_ERROR)
 472                 bp->bio_error = EIO;
 473         else
 474                 bp->bio_resid = 0;
 475
 476         xbd_free_command(cm);
 477         biodone(bp);
 478 }
 479
 480 static void
 481 xbd_int(void *xsc)
 482 {
 483         struct xbd_softc *sc = xsc;
 484         struct xbd_command *cm;
 485         blkif_response_t *bret;
 486         RING_IDX i, rp;
 487         int op;
 488
 489         mtx_lock(&sc->xbd_io_lock);
 490
 491         if (__predict_false(sc->xbd_state == XBD_STATE_DISCONNECTED)) {
 492                 mtx_unlock(&sc->xbd_io_lock);
 493                 return;
 494         }
 495
 496  again:
 497         rp = sc->xbd_ring.sring->rsp_prod;
 498         rmb(); /* Ensure we see queued responses up to 'rp'. */
 499
 500         for (i = sc->xbd_ring.rsp_cons; i != rp;) {
 501                 bret = RING_GET_RESPONSE(&sc->xbd_ring, i);
 502                 cm   = &sc->xbd_shadow[bret->id];
 503
 504                 xbd_remove_cm(cm, XBD_Q_BUSY);
 505                 gnttab_end_foreign_access_references(cm->cm_nseg,
 506                     cm->cm_sg_refs);
 507                 i++;
 508
 509                 if (cm->cm_operation == BLKIF_OP_READ)
 510                         op = BUS_DMASYNC_POSTREAD;
 511                 else if (cm->cm_operation == BLKIF_OP_WRITE ||
 512                     cm->cm_operation == BLKIF_OP_WRITE_BARRIER)
 513                         op = BUS_DMASYNC_POSTWRITE;
 514                 else
 515                         op = 0;
 516                 bus_dmamap_sync(sc->xbd_io_dmat, cm->cm_map, op);
 517                 bus_dmamap_unload(sc->xbd_io_dmat, cm->cm_map);
 518
 519                 /*
 520                  * Release any hold this command has on future command
 521                  * dispatch.
 522                  */
 523                 xbd_cm_thaw(sc, cm);
 524
 525                 /*
 526                  * Directly call the i/o complete routine to save an
 527                  * an indirection in the common case.
 528                  */
 529                 cm->cm_status = bret->status;
 530                 if (cm->cm_bp)
 531                         xbd_bio_complete(sc, cm);
 532                 else if (cm->cm_complete != NULL)
 533                         cm->cm_complete(cm);
 534                 else
 535                         xbd_free_command(cm);
 536         }
 537
 538         sc->xbd_ring.rsp_cons = i;
 539
 540         if (i != sc->xbd_ring.req_prod_pvt) {
 541                 int more_to_do;
 542                 RING_FINAL_CHECK_FOR_RESPONSES(&sc->xbd_ring, more_to_do);
 543                 if (more_to_do)
 544                         goto again;
 545         } else {
 546                 sc->xbd_ring.sring->rsp_event = i + 1;
 547         }
 548
 549         if (xbd_queue_length(sc, XBD_Q_BUSY) == 0)
 550                 xbd_thaw(sc, XBDF_WAIT_IDLE);
 551
 552         xbd_startio(sc);
 553
 554         if (__predict_false(sc->xbd_state == XBD_STATE_SUSPENDED))
 555                 wakeup(&sc->xbd_cm_q[XBD_Q_BUSY]);
 556
 557         mtx_unlock(&sc->xbd_io_lock);
 558 }
 559
 560 /*------------------------------- Dump Support -------------------------------*/
 561 /**
 562  * Quiesce the disk writes for a dump file before allowing the next buffer.
 563  */
 564 static void
 565 xbd_quiesce(struct xbd_softc *sc)
 566 {
 567         int mtd;
 568
 569         // While there are outstanding requests
 570         while (xbd_queue_length(sc, XBD_Q_BUSY) != 0) {
 571                 RING_FINAL_CHECK_FOR_RESPONSES(&sc->xbd_ring, mtd);
 572                 if (mtd) {
 573                         /* Received request completions, update queue. */
 574                         xbd_int(sc);
 575                 }
 576                 if (xbd_queue_length(sc, XBD_Q_BUSY) != 0) {
 577                         /*
 578                          * Still pending requests, wait for the disk i/o
 579                          * to complete.
 580                          */
 581                         HYPERVISOR_yield();
 582                 }
 583         }
 584 }
 585
 586 /* Kernel dump function for a paravirtualized disk device */
 587 static void
 588 xbd_dump_complete(struct xbd_command *cm)
 589 {
 590
 591         xbd_enqueue_cm(cm, XBD_Q_COMPLETE);
 592 }
 593
 594 static int
 595 xbd_dump(void *arg, void *virtual, vm_offset_t physical, off_t offset,
 596     size_t length)
 597 {
 598         struct disk *dp = arg;
 599         struct xbd_softc *sc = dp->d_drv1;
 600         struct xbd_command *cm;
 601         size_t chunk;
 602         int sbp;
 603         int rc = 0;
 604
 605         if (length == 0)
 606                 return (0);
 607
 608         xbd_quiesce(sc);        /* All quiet on the western front. */
 609
 610         /*
 611          * If this lock is held, then this module is failing, and a
 612          * successful kernel dump is highly unlikely anyway.
 613          */
 614         mtx_lock(&sc->xbd_io_lock);
 615
 616         /* Split the 64KB block as needed */
 617         for (sbp=0; length > 0; sbp++) {
 618                 cm = xbd_dequeue_cm(sc, XBD_Q_FREE);
 619                 if (cm == NULL) {
 620                         mtx_unlock(&sc->xbd_io_lock);
 621                         device_printf(sc->xbd_dev, "dump: no more commands?\n");
 622                         return (EBUSY);
 623                 }
 624
 625                 if (gnttab_alloc_grant_references(sc->xbd_max_request_segments,
 626                     &cm->cm_gref_head) != 0) {
 627                         xbd_free_command(cm);
 628                         mtx_unlock(&sc->xbd_io_lock);
 629                         device_printf(sc->xbd_dev, "no more grant allocs?\n");
 630                         return (EBUSY);
 631                 }
 632
 633                 chunk = length > sc->xbd_max_request_size ?
 634                     sc->xbd_max_request_size : length;
 635                 cm->cm_data = virtual;
 636                 cm->cm_datalen = chunk;
 637                 cm->cm_operation = BLKIF_OP_WRITE;
 638                 cm->cm_sector_number = offset / dp->d_sectorsize;
 639                 cm->cm_complete = xbd_dump_complete;
 640
 641                 xbd_enqueue_cm(cm, XBD_Q_READY);
 642
 643                 length -= chunk;
 644                 offset += chunk;
 645                 virtual = (char *) virtual + chunk;
 646         }
 647
 648         /* Tell DOM0 to do the I/O */
 649         xbd_startio(sc);
 650         mtx_unlock(&sc->xbd_io_lock);
 651
 652         /* Poll for the completion. */
 653         xbd_quiesce(sc);        /* All quite on the eastern front */
 654
 655         /* If there were any errors, bail out... */
 656         while ((cm = xbd_dequeue_cm(sc, XBD_Q_COMPLETE)) != NULL) {
 657                 if (cm->cm_status != BLKIF_RSP_OKAY) {
 658                         device_printf(sc->xbd_dev,
 659                             "Dump I/O failed at sector %jd\n",
 660                             cm->cm_sector_number);
 661                         rc = EIO;
 662                 }
 663                 xbd_free_command(cm);
 664         }
 665
 666         return (rc);
 667 }
 668
 669 /*----------------------------- Disk Entrypoints -----------------------------*/
 670 static int
 671 xbd_open(struct disk *dp)
 672 {
 673         struct xbd_softc *sc = dp->d_drv1;
 674
 675         if (sc == NULL) {
 676                 printf("xbd%d: not found", dp->d_unit);
 677                 return (ENXIO);
 678         }
 679
 680         sc->xbd_flags |= XBDF_OPEN;
 681         sc->xbd_users++;
 682         return (0);
 683 }
 684
 685 static int
 686 xbd_close(struct disk *dp)
 687 {
 688         struct xbd_softc *sc = dp->d_drv1;
 689
 690         if (sc == NULL)
 691                 return (ENXIO);
 692         sc->xbd_flags &= ~XBDF_OPEN;
 693         if (--(sc->xbd_users) == 0) {
 694                 /*
 695                  * Check whether we have been instructed to close.  We will
 696                  * have ignored this request initially, as the device was
 697                  * still mounted.
 698                  */
 699                 if (xenbus_get_otherend_state(sc->xbd_dev) ==
 700                     XenbusStateClosing)
 701                         xbd_closing(sc->xbd_dev);
 702         }
 703         return (0);
 704 }
 705
 706 static int
 707 xbd_ioctl(struct disk *dp, u_long cmd, void *addr, int flag, struct thread *td)
 708 {
 709         struct xbd_softc *sc = dp->d_drv1;
 710
 711         if (sc == NULL)
 712                 return (ENXIO);
 713
 714         return (ENOTTY);
 715 }
 716
 717 /*
 718  * Read/write routine for a buffer.  Finds the proper unit, place it on
 719  * the sortq and kick the controller.
 720  */
 721 static void
 722 xbd_strategy(struct bio *bp)
 723 {
 724         struct xbd_softc *sc = bp->bio_disk->d_drv1;
 725
 726         /* bogus disk? */
 727         if (sc == NULL) {
 728                 bp->bio_error = EINVAL;
 729                 bp->bio_flags |= BIO_ERROR;
 730                 bp->bio_resid = bp->bio_bcount;
 731                 biodone(bp);
 732                 return;
 733         }
 734
 735         /*
 736          * Place it in the queue of disk activities for this disk
 737          */
 738         mtx_lock(&sc->xbd_io_lock);
 739
 740         xbd_enqueue_bio(sc, bp);
 741         xbd_startio(sc);
 742
 743         mtx_unlock(&sc->xbd_io_lock);
 744         return;
 745 }
 746
 747 /*------------------------------ Ring Management -----------------------------*/
 748 static int
 749 xbd_alloc_ring(struct xbd_softc *sc)
 750 {
 751         blkif_sring_t *sring;
 752         uintptr_t sring_page_addr;
 753         int error;
 754         int i;
 755
 756         sring = malloc(sc->xbd_ring_pages * PAGE_SIZE, M_XENBLOCKFRONT,
 757             M_NOWAIT|M_ZERO);
 758         if (sring == NULL) {
 759                 xenbus_dev_fatal(sc->xbd_dev, ENOMEM, "allocating shared ring");
 760                 return (ENOMEM);
 761         }
 762         SHARED_RING_INIT(sring);
 763         FRONT_RING_INIT(&sc->xbd_ring, sring, sc->xbd_ring_pages * PAGE_SIZE);
 764
 765         for (i = 0, sring_page_addr = (uintptr_t)sring;
 766              i < sc->xbd_ring_pages;
 767              i++, sring_page_addr += PAGE_SIZE) {
 768
 769                 error = xenbus_grant_ring(sc->xbd_dev,
 770                     (vtophys(sring_page_addr) >> PAGE_SHIFT),
 771                     &sc->xbd_ring_ref[i]);
 772                 if (error) {
 773                         xenbus_dev_fatal(sc->xbd_dev, error,
 774                             "granting ring_ref(%d)", i);
 775                         return (error);
 776                 }
 777         }
 778         if (sc->xbd_ring_pages == 1) {
 779                 error = xs_printf(XST_NIL, xenbus_get_node(sc->xbd_dev),
 780                     "ring-ref", "%u", sc->xbd_ring_ref[0]);
 781                 if (error) {
 782                         xenbus_dev_fatal(sc->xbd_dev, error,
 783                             "writing %s/ring-ref",
 784                             xenbus_get_node(sc->xbd_dev));
 785                         return (error);
 786                 }
 787         } else {
 788                 for (i = 0; i < sc->xbd_ring_pages; i++) {
 789                         char ring_ref_name[]= "ring_refXX";
 790
 791                         snprintf(ring_ref_name, sizeof(ring_ref_name),
 792                             "ring-ref%u", i);
 793                         error = xs_printf(XST_NIL, xenbus_get_node(sc->xbd_dev),
 794                              ring_ref_name, "%u", sc->xbd_ring_ref[i]);
 795                         if (error) {
 796                                 xenbus_dev_fatal(sc->xbd_dev, error,
 797                                     "writing %s/%s",
 798                                     xenbus_get_node(sc->xbd_dev),
 799                                     ring_ref_name);
 800                                 return (error);
 801                         }
 802                 }
 803         }
 804
 805         error = xen_intr_alloc_and_bind_local_port(sc->xbd_dev,
 806             xenbus_get_otherend_id(sc->xbd_dev), NULL, xbd_int, sc,
 807             INTR_TYPE_BIO | INTR_MPSAFE, &sc->xen_intr_handle);
 808         if (error) {
 809                 xenbus_dev_fatal(sc->xbd_dev, error,
 810                     "xen_intr_alloc_and_bind_local_port failed");
 811                 return (error);
 812         }
 813
 814         return (0);
 815 }
 816
 817 static void
 818 xbd_free_ring(struct xbd_softc *sc)
 819 {
 820         int i;
 821
 822         if (sc->xbd_ring.sring == NULL)
 823                 return;
 824
 825         for (i = 0; i < sc->xbd_ring_pages; i++) {
 826                 if (sc->xbd_ring_ref[i] != GRANT_REF_INVALID) {
 827                         gnttab_end_foreign_access_ref(sc->xbd_ring_ref[i]);
 828                         sc->xbd_ring_ref[i] = GRANT_REF_INVALID;
 829                 }
 830         }
 831         free(sc->xbd_ring.sring, M_XENBLOCKFRONT);
 832         sc->xbd_ring.sring = NULL;
 833 }
 834
 835 /*-------------------------- Initialization/Teardown -------------------------*/
 836 static int
 837 xbd_feature_string(struct xbd_softc *sc, char *features, size_t len)
 838 {
 839         struct sbuf sb;
 840         int feature_cnt;
 841
 842         sbuf_new(&sb, features, len, SBUF_FIXEDLEN);
 843
 844         feature_cnt = 0;
 845         if ((sc->xbd_flags & XBDF_FLUSH) != 0) {
 846                 sbuf_printf(&sb, "flush");
 847                 feature_cnt++;
 848         }
 849
 850         if ((sc->xbd_flags & XBDF_BARRIER) != 0) {
 851                 if (feature_cnt != 0)
 852                         sbuf_printf(&sb, ", ");
 853                 sbuf_printf(&sb, "write_barrier");
 854                 feature_cnt++;
 855         }
 856
 857         if ((sc->xbd_flags & XBDF_DISCARD) != 0) {
 858                 if (feature_cnt != 0)
 859                         sbuf_printf(&sb, ", ");
 860                 sbuf_printf(&sb, "discard");
 861                 feature_cnt++;
 862         }
 863
 864         if ((sc->xbd_flags & XBDF_PERSISTENT) != 0) {
 865                 if (feature_cnt != 0)
 866                         sbuf_printf(&sb, ", ");
 867                 sbuf_printf(&sb, "persistent_grants");
 868                 feature_cnt++;
 869         }
 870
 871         (void) sbuf_finish(&sb);
 872         return (sbuf_len(&sb));
 873 }
 874
 875 static int
 876 xbd_sysctl_features(SYSCTL_HANDLER_ARGS)
 877 {
 878         char features[80];
 879         struct xbd_softc *sc = arg1;
 880         int error;
 881         int len;
 882
 883         error = sysctl_wire_old_buffer(req, 0);
 884         if (error != 0)
 885                 return (error);
 886
 887         len = xbd_feature_string(sc, features, sizeof(features));
 888
 889         /* len is -1 on error, which will make the SYSCTL_OUT a no-op. */
 890         return (SYSCTL_OUT(req, features, len + 1/*NUL*/));
 891 }
 892
 893 static void
 894 xbd_setup_sysctl(struct xbd_softc *xbd)
 895 {
 896         struct sysctl_ctx_list *sysctl_ctx = NULL;
 897         struct sysctl_oid *sysctl_tree = NULL;
 898         struct sysctl_oid_list *children;
 899
 900         sysctl_ctx = device_get_sysctl_ctx(xbd->xbd_dev);
 901         if (sysctl_ctx == NULL)
 902                 return;
 903
 904         sysctl_tree = device_get_sysctl_tree(xbd->xbd_dev);
 905         if (sysctl_tree == NULL)
 906                 return;
 907
 908         children = SYSCTL_CHILDREN(sysctl_tree);
 909         SYSCTL_ADD_UINT(sysctl_ctx, children, OID_AUTO,
 910             "max_requests", CTLFLAG_RD, &xbd->xbd_max_requests, -1,
 911             "maximum outstanding requests (negotiated)");
 912
 913         SYSCTL_ADD_UINT(sysctl_ctx, children, OID_AUTO,
 914             "max_request_segments", CTLFLAG_RD,
 915             &xbd->xbd_max_request_segments, 0,
 916             "maximum number of pages per requests (negotiated)");
 917
 918         SYSCTL_ADD_UINT(sysctl_ctx, children, OID_AUTO,
 919             "max_request_size", CTLFLAG_RD, &xbd->xbd_max_request_size, 0,
 920             "maximum size in bytes of a request (negotiated)");
 921
 922         SYSCTL_ADD_UINT(sysctl_ctx, children, OID_AUTO,
 923             "ring_pages", CTLFLAG_RD, &xbd->xbd_ring_pages, 0,
 924             "communication channel pages (negotiated)");
 925
 926         SYSCTL_ADD_PROC(sysctl_ctx, children, OID_AUTO,
 927             "features", CTLTYPE_STRING|CTLFLAG_RD, xbd, 0,
 928             xbd_sysctl_features, "A", "protocol features (negotiated)");
 929 }
 930
 931 /*
 932  * Translate Linux major/minor to an appropriate name and unit
 933  * number. For HVM guests, this allows us to use the same drive names
 934  * with blkfront as the emulated drives, easing transition slightly.
 935  */
 936 static void
 937 xbd_vdevice_to_unit(uint32_t vdevice, int *unit, const char **name)
 938 {
 939         static struct vdev_info {
 940                 int major;
 941                 int shift;
 942                 int base;
 943                 const char *name;
 944         } info[] = {
 945                 {3,     6,      0,      "ada"}, /* ide0 */
 946                 {22,    6,      2,      "ada"}, /* ide1 */
 947                 {33,    6,      4,      "ada"}, /* ide2 */
 948                 {34,    6,      6,      "ada"}, /* ide3 */
 949                 {56,    6,      8,      "ada"}, /* ide4 */
 950                 {57,    6,      10,     "ada"}, /* ide5 */
 951                 {88,    6,      12,     "ada"}, /* ide6 */
 952                 {89,    6,      14,     "ada"}, /* ide7 */
 953                 {90,    6,      16,     "ada"}, /* ide8 */
 954                 {91,    6,      18,     "ada"}, /* ide9 */
 955
 956                 {8,     4,      0,      "da"},  /* scsi disk0 */
 957                 {65,    4,      16,     "da"},  /* scsi disk1 */
 958                 {66,    4,      32,     "da"},  /* scsi disk2 */
 959                 {67,    4,      48,     "da"},  /* scsi disk3 */
 960                 {68,    4,      64,     "da"},  /* scsi disk4 */
 961                 {69,    4,      80,     "da"},  /* scsi disk5 */
 962                 {70,    4,      96,     "da"},  /* scsi disk6 */
 963                 {71,    4,      112,    "da"},  /* scsi disk7 */
 964                 {128,   4,      128,    "da"},  /* scsi disk8 */
 965                 {129,   4,      144,    "da"},  /* scsi disk9 */
 966                 {130,   4,      160,    "da"},  /* scsi disk10 */
 967                 {131,   4,      176,    "da"},  /* scsi disk11 */
 968                 {132,   4,      192,    "da"},  /* scsi disk12 */
 969                 {133,   4,      208,    "da"},  /* scsi disk13 */
 970                 {134,   4,      224,    "da"},  /* scsi disk14 */
 971                 {135,   4,      240,    "da"},  /* scsi disk15 */
 972
 973                 {202,   4,      0,      "xbd"}, /* xbd */
 974
 975                 {0,     0,      0,      NULL},
 976         };
 977         int major = vdevice >> 8;
 978         int minor = vdevice & 0xff;
 979         int i;
 980
 981         if (vdevice & (1 << 28)) {
 982                 *unit = (vdevice & ((1 << 28) - 1)) >> 8;
 983                 *name = "xbd";
 984                 return;
 985         }
 986
 987         for (i = 0; info[i].major; i++) {
 988                 if (info[i].major == major) {
 989                         *unit = info[i].base + (minor >> info[i].shift);
 990                         *name = info[i].name;
 991                         return;
 992                 }
 993         }
 994
 995         *unit = minor >> 4;
 996         *name = "xbd";
 997 }
 998
 999 int
1000 xbd_instance_create(struct xbd_softc *sc, blkif_sector_t sectors,
1001     int vdevice, uint16_t vdisk_info, unsigned long sector_size,
1002     unsigned long phys_sector_size)
1003 {
1004         char features[80];
1005         int unit, error = 0;
1006         const char *name;
1007
1008         xbd_vdevice_to_unit(vdevice, &unit, &name);
1009
1010         sc->xbd_unit = unit;
1011
1012         if (strcmp(name, "xbd") != 0)
1013                 device_printf(sc->xbd_dev, "attaching as %s%d\n", name, unit);
1014
1015         if (xbd_feature_string(sc, features, sizeof(features)) > 0) {
1016                 device_printf(sc->xbd_dev, "features: %s\n",
1017                     features);
1018         }
1019
1020         sc->xbd_disk = disk_alloc();
1021         sc->xbd_disk->d_unit = sc->xbd_unit;
1022         sc->xbd_disk->d_open = xbd_open;
1023         sc->xbd_disk->d_close = xbd_close;
1024         sc->xbd_disk->d_ioctl = xbd_ioctl;
1025         sc->xbd_disk->d_strategy = xbd_strategy;
1026         sc->xbd_disk->d_dump = xbd_dump;
1027         sc->xbd_disk->d_name = name;
1028         sc->xbd_disk->d_drv1 = sc;
1029         sc->xbd_disk->d_sectorsize = sector_size;
1030         sc->xbd_disk->d_stripesize = phys_sector_size;
1031         sc->xbd_disk->d_stripeoffset = 0;
1032
1033         sc->xbd_disk->d_mediasize = sectors * sector_size;
1034         sc->xbd_disk->d_maxsize = sc->xbd_max_request_size;
1035         sc->xbd_disk->d_flags = DISKFLAG_UNMAPPED_BIO;
1036         if ((sc->xbd_flags & (XBDF_FLUSH|XBDF_BARRIER)) != 0) {
1037                 sc->xbd_disk->d_flags |= DISKFLAG_CANFLUSHCACHE;
1038                 device_printf(sc->xbd_dev,
1039                     "synchronize cache commands enabled.\n");
1040         }
1041         disk_create(sc->xbd_disk, DISK_VERSION);
1042
1043         return error;
1044 }
1045
1046 static void
1047 xbd_free(struct xbd_softc *sc)
1048 {
1049         int i;
1050
1051         /* Prevent new requests being issued until we fix things up. */
1052         mtx_lock(&sc->xbd_io_lock);
1053         sc->xbd_state = XBD_STATE_DISCONNECTED;
1054         mtx_unlock(&sc->xbd_io_lock);
1055
1056         /* Free resources associated with old device channel. */
1057         xbd_free_ring(sc);
1058         if (sc->xbd_shadow) {
1059
1060                 for (i = 0; i < sc->xbd_max_requests; i++) {
1061                         struct xbd_command *cm;
1062
1063                         cm = &sc->xbd_shadow[i];
1064                         if (cm->cm_sg_refs != NULL) {
1065                                 free(cm->cm_sg_refs, M_XENBLOCKFRONT);
1066                                 cm->cm_sg_refs = NULL;
1067                         }
1068
1069                         if (cm->cm_indirectionpages != NULL) {
1070                                 gnttab_end_foreign_access_references(
1071                                     sc->xbd_max_request_indirectpages,
1072                                     &cm->cm_indirectionrefs[0]);
1073                                 contigfree(cm->cm_indirectionpages, PAGE_SIZE *
1074                                     sc->xbd_max_request_indirectpages,
1075                                     M_XENBLOCKFRONT);
1076                                 cm->cm_indirectionpages = NULL;
1077                         }
1078
1079                         bus_dmamap_destroy(sc->xbd_io_dmat, cm->cm_map);
1080                 }
1081                 free(sc->xbd_shadow, M_XENBLOCKFRONT);
1082                 sc->xbd_shadow = NULL;
1083
1084                 bus_dma_tag_destroy(sc->xbd_io_dmat);
1085
1086                 xbd_initq_cm(sc, XBD_Q_FREE);
1087                 xbd_initq_cm(sc, XBD_Q_READY);
1088                 xbd_initq_cm(sc, XBD_Q_COMPLETE);
1089         }
1090
1091         xen_intr_unbind(&sc->xen_intr_handle);
1092
1093 }
1094
1095 /*--------------------------- State Change Handlers --------------------------*/
1096 static void
1097 xbd_initialize(struct xbd_softc *sc)
1098 {
1099         const char *otherend_path;
1100         const char *node_path;
1101         uint32_t max_ring_page_order;
1102         int error;
1103
1104         if (xenbus_get_state(sc->xbd_dev) != XenbusStateInitialising) {
1105                 /* Initialization has already been performed. */
1106                 return;
1107         }
1108
1109         /*
1110          * Protocol defaults valid even if negotiation for a
1111          * setting fails.
1112          */
1113         max_ring_page_order = 0;
1114         sc->xbd_ring_pages = 1;
1115
1116         /*
1117          * Protocol negotiation.
1118          *
1119          * \note xs_gather() returns on the first encountered error, so
1120          *       we must use independent calls in order to guarantee
1121          *       we don't miss information in a sparsly populated back-end
1122          *       tree.
1123          *
1124          * \note xs_scanf() does not update variables for unmatched
1125          *       fields.
1126          */
1127         otherend_path = xenbus_get_otherend_path(sc->xbd_dev);
1128         node_path = xenbus_get_node(sc->xbd_dev);
1129
1130         /* Support both backend schemes for relaying ring page limits. */
1131         (void)xs_scanf(XST_NIL, otherend_path,
1132             "max-ring-page-order", NULL, "%" PRIu32,
1133             &max_ring_page_order);
1134         sc->xbd_ring_pages = 1 << max_ring_page_order;
1135         (void)xs_scanf(XST_NIL, otherend_path,
1136             "max-ring-pages", NULL, "%" PRIu32,
1137             &sc->xbd_ring_pages);
1138         if (sc->xbd_ring_pages < 1)
1139                 sc->xbd_ring_pages = 1;
1140
1141         if (sc->xbd_ring_pages > XBD_MAX_RING_PAGES) {
1142                 device_printf(sc->xbd_dev,
1143                     "Back-end specified ring-pages of %u "
1144                     "limited to front-end limit of %u.\n",
1145                     sc->xbd_ring_pages, XBD_MAX_RING_PAGES);
1146                 sc->xbd_ring_pages = XBD_MAX_RING_PAGES;
1147         }
1148
1149         if (powerof2(sc->xbd_ring_pages) == 0) {
1150                 uint32_t new_page_limit;
1151
1152                 new_page_limit = 0x01 << (fls(sc->xbd_ring_pages) - 1);
1153                 device_printf(sc->xbd_dev,
1154                     "Back-end specified ring-pages of %u "
1155                     "is not a power of 2. Limited to %u.\n",
1156                     sc->xbd_ring_pages, new_page_limit);
1157                 sc->xbd_ring_pages = new_page_limit;
1158         }
1159
1160         sc->xbd_max_requests =
1161             BLKIF_MAX_RING_REQUESTS(sc->xbd_ring_pages * PAGE_SIZE);
1162         if (sc->xbd_max_requests > XBD_MAX_REQUESTS) {
1163                 device_printf(sc->xbd_dev,
1164                     "Back-end specified max_requests of %u "
1165                     "limited to front-end limit of %zu.\n",
1166                     sc->xbd_max_requests, XBD_MAX_REQUESTS);
1167                 sc->xbd_max_requests = XBD_MAX_REQUESTS;
1168         }
1169
1170         if (xbd_alloc_ring(sc) != 0)
1171                 return;
1172
1173         /* Support both backend schemes for relaying ring page limits. */
1174         if (sc->xbd_ring_pages > 1) {
1175                 error = xs_printf(XST_NIL, node_path,
1176                     "num-ring-pages","%u",
1177                     sc->xbd_ring_pages);
1178                 if (error) {
1179                         xenbus_dev_fatal(sc->xbd_dev, error,
1180                             "writing %s/num-ring-pages",
1181                             node_path);
1182                         return;
1183                 }
1184
1185                 error = xs_printf(XST_NIL, node_path,
1186                     "ring-page-order", "%u",
1187                     fls(sc->xbd_ring_pages) - 1);
1188                 if (error) {
1189                         xenbus_dev_fatal(sc->xbd_dev, error,
1190                             "writing %s/ring-page-order",
1191                             node_path);
1192                         return;
1193                 }
1194         }
1195
1196         error = xs_printf(XST_NIL, node_path, "event-channel",
1197             "%u", xen_intr_port(sc->xen_intr_handle));
1198         if (error) {
1199                 xenbus_dev_fatal(sc->xbd_dev, error,
1200                     "writing %s/event-channel",
1201                     node_path);
1202                 return;
1203         }
1204
1205         error = xs_printf(XST_NIL, node_path, "protocol",
1206             "%s", XEN_IO_PROTO_ABI_NATIVE);
1207         if (error) {
1208                 xenbus_dev_fatal(sc->xbd_dev, error,
1209                     "writing %s/protocol",
1210                     node_path);
1211                 return;
1212         }
1213
1214         xenbus_set_state(sc->xbd_dev, XenbusStateInitialised);
1215 }
1216
1217 /*
1218  * Invoked when the backend is finally 'ready' (and has published
1219  * the details about the physical device - #sectors, size, etc).
1220  */
1221 static void
1222 xbd_connect(struct xbd_softc *sc)
1223 {
1224         device_t dev = sc->xbd_dev;
1225         unsigned long sectors, sector_size, phys_sector_size;
1226         unsigned int binfo;
1227         int err, feature_barrier, feature_flush;
1228         int i, j;
1229
1230         if (sc->xbd_state == XBD_STATE_CONNECTED ||
1231             sc->xbd_state == XBD_STATE_SUSPENDED)
1232                 return;
1233
1234         DPRINTK("blkfront.c:connect:%s.\n", xenbus_get_otherend_path(dev));
1235
1236         err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
1237             "sectors", "%lu", &sectors,
1238             "info", "%u", &binfo,
1239             "sector-size", "%lu", &sector_size,
1240             NULL);
1241         if (err) {
1242                 xenbus_dev_fatal(dev, err,
1243                     "reading backend fields at %s",
1244                     xenbus_get_otherend_path(dev));
1245                 return;
1246         }
1247         if ((sectors == 0) || (sector_size == 0)) {
1248                 xenbus_dev_fatal(dev, 0,
1249                     "invalid parameters from %s:"
1250                     " sectors = %lu, sector_size = %lu",
1251                     xenbus_get_otherend_path(dev),
1252                     sectors, sector_size);
1253                 return;
1254         }
1255         err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
1256              "physical-sector-size", "%lu", &phys_sector_size,
1257              NULL);
1258         if (err || phys_sector_size <= sector_size)
1259                 phys_sector_size = 0;
1260         err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
1261              "feature-barrier", "%d", &feature_barrier,
1262              NULL);
1263         if (err == 0 && feature_barrier != 0)
1264                 sc->xbd_flags |= XBDF_BARRIER;
1265
1266         err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
1267              "feature-flush-cache", "%d", &feature_flush,
1268              NULL);
1269         if (err == 0 && feature_flush != 0)
1270                 sc->xbd_flags |= XBDF_FLUSH;
1271
1272         err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
1273             "feature-max-indirect-segments", "%" PRIu32,
1274             &sc->xbd_max_request_segments, NULL);
1275         if ((err != 0) || (xbd_enable_indirect == 0))
1276                 sc->xbd_max_request_segments = 0;
1277         if (sc->xbd_max_request_segments > XBD_MAX_INDIRECT_SEGMENTS)
1278                 sc->xbd_max_request_segments = XBD_MAX_INDIRECT_SEGMENTS;
1279         if (sc->xbd_max_request_segments > XBD_SIZE_TO_SEGS(MAXPHYS))
1280                 sc->xbd_max_request_segments = XBD_SIZE_TO_SEGS(MAXPHYS);
1281         sc->xbd_max_request_indirectpages =
1282             XBD_INDIRECT_SEGS_TO_PAGES(sc->xbd_max_request_segments);
1283         if (sc->xbd_max_request_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
1284                 sc->xbd_max_request_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
1285         sc->xbd_max_request_size =
1286             XBD_SEGS_TO_SIZE(sc->xbd_max_request_segments);
1287
1288         /* Allocate datastructures based on negotiated values. */
1289         err = bus_dma_tag_create(
1290             bus_get_dma_tag(sc->xbd_dev),       /* parent */
1291             512, PAGE_SIZE,                     /* algnmnt, boundary */
1292             BUS_SPACE_MAXADDR,                  /* lowaddr */
1293             BUS_SPACE_MAXADDR,                  /* highaddr */
1294             NULL, NULL,                         /* filter, filterarg */
1295             sc->xbd_max_request_size,
1296             sc->xbd_max_request_segments,
1297             PAGE_SIZE,                          /* maxsegsize */
1298             BUS_DMA_ALLOCNOW,                   /* flags */
1299             busdma_lock_mutex,                  /* lockfunc */
1300             &sc->xbd_io_lock,                   /* lockarg */
1301             &sc->xbd_io_dmat);
1302         if (err != 0) {
1303                 xenbus_dev_fatal(sc->xbd_dev, err,
1304                     "Cannot allocate parent DMA tag\n");
1305                 return;
1306         }
1307
1308         /* Per-transaction data allocation. */
1309         sc->xbd_shadow = malloc(sizeof(*sc->xbd_shadow) * sc->xbd_max_requests,
1310             M_XENBLOCKFRONT, M_NOWAIT|M_ZERO);
1311         if (sc->xbd_shadow == NULL) {
1312                 bus_dma_tag_destroy(sc->xbd_io_dmat);
1313                 xenbus_dev_fatal(sc->xbd_dev, ENOMEM,
1314                     "Cannot allocate request structures\n");
1315                 return;
1316         }
1317
1318         for (i = 0; i < sc->xbd_max_requests; i++) {
1319                 struct xbd_command *cm;
1320                 void * indirectpages;
1321
1322                 cm = &sc->xbd_shadow[i];
1323                 cm->cm_sg_refs = malloc(
1324                     sizeof(grant_ref_t) * sc->xbd_max_request_segments,
1325                     M_XENBLOCKFRONT, M_NOWAIT);
1326                 if (cm->cm_sg_refs == NULL)
1327                         break;
1328                 cm->cm_id = i;
1329                 cm->cm_flags = XBDCF_INITIALIZER;
1330                 cm->cm_sc = sc;
1331                 if (bus_dmamap_create(sc->xbd_io_dmat, 0, &cm->cm_map) != 0)
1332                         break;
1333                 if (sc->xbd_max_request_indirectpages > 0) {
1334                         indirectpages = contigmalloc(
1335                             PAGE_SIZE * sc->xbd_max_request_indirectpages,
1336                             M_XENBLOCKFRONT, M_ZERO | M_NOWAIT, 0, ~0,
1337                             PAGE_SIZE, 0);
1338                         if (indirectpages == NULL)
1339                                 sc->xbd_max_request_indirectpages = 0;
1340                 } else {
1341                         indirectpages = NULL;
1342                 }
1343                 for (j = 0; j < sc->xbd_max_request_indirectpages; j++) {
1344                         if (gnttab_grant_foreign_access(
1345                             xenbus_get_otherend_id(sc->xbd_dev),
1346                             (vtophys(indirectpages) >> PAGE_SHIFT) + j,
1347                             1 /* grant read-only access */,
1348                             &cm->cm_indirectionrefs[j]))
1349                                 break;
1350                 }
1351                 if (j < sc->xbd_max_request_indirectpages) {
1352                         contigfree(indirectpages,
1353                             PAGE_SIZE * sc->xbd_max_request_indirectpages,
1354                             M_XENBLOCKFRONT);
1355                         break;
1356                 }
1357                 cm->cm_indirectionpages = indirectpages;
1358                 xbd_free_command(cm);
1359         }
1360
1361         if (sc->xbd_disk == NULL) {
1362                 device_printf(dev, "%juMB <%s> at %s",
1363                     (uintmax_t) sectors / (1048576 / sector_size),
1364                     device_get_desc(dev),
1365                     xenbus_get_node(dev));
1366                 bus_print_child_footer(device_get_parent(dev), dev);
1367
1368                 xbd_instance_create(sc, sectors, sc->xbd_vdevice, binfo,
1369                     sector_size, phys_sector_size);
1370         }
1371
1372         (void)xenbus_set_state(dev, XenbusStateConnected);
1373
1374         /* Kick pending requests. */
1375         mtx_lock(&sc->xbd_io_lock);
1376         sc->xbd_state = XBD_STATE_CONNECTED;
1377         xbd_startio(sc);
1378         sc->xbd_flags |= XBDF_READY;
1379         mtx_unlock(&sc->xbd_io_lock);
1380 }
1381
1382 /**
1383  * Handle the change of state of the backend to Closing.  We must delete our
1384  * device-layer structures now, to ensure that writes are flushed through to
1385  * the backend.  Once this is done, we can switch to Closed in
1386  * acknowledgement.
1387  */
1388 static void
1389 xbd_closing(device_t dev)
1390 {
1391         struct xbd_softc *sc = device_get_softc(dev);
1392
1393         xenbus_set_state(dev, XenbusStateClosing);
1394
1395         DPRINTK("xbd_closing: %s removed\n", xenbus_get_node(dev));
1396
1397         if (sc->xbd_disk != NULL) {
1398                 disk_destroy(sc->xbd_disk);
1399                 sc->xbd_disk = NULL;
1400         }
1401
1402         xenbus_set_state(dev, XenbusStateClosed);
1403 }
1404
1405 /*---------------------------- NewBus Entrypoints ----------------------------*/
1406 static int
1407 xbd_probe(device_t dev)
1408 {
1409         if (strcmp(xenbus_get_type(dev), "vbd") != 0)
1410                 return (ENXIO);
1411
1412         if (xen_hvm_domain() && xen_disable_pv_disks != 0)
1413                 return (ENXIO);
1414
1415         if (xen_hvm_domain()) {
1416                 int error;
1417                 char *type;
1418
1419                 /*
1420                  * When running in an HVM domain, IDE disk emulation is
1421                  * disabled early in boot so that native drivers will
1422                  * not see emulated hardware.  However, CDROM device
1423                  * emulation cannot be disabled.
1424                  *
1425                  * Through use of FreeBSD's vm_guest and xen_hvm_domain()
1426                  * APIs, we could modify the native CDROM driver to fail its
1427                  * probe when running under Xen.  Unfortunatlely, the PV
1428                  * CDROM support in XenServer (up through at least version
1429                  * 6.2) isn't functional, so we instead rely on the emulated
1430                  * CDROM instance, and fail to attach the PV one here in
1431                  * the blkfront driver.
1432                  */
1433                 error = xs_read(XST_NIL, xenbus_get_node(dev),
1434                     "device-type", NULL, (void **) &type);
1435                 if (error)
1436                         return (ENXIO);
1437
1438                 if (strncmp(type, "cdrom", 5) == 0) {
1439                         free(type, M_XENSTORE);
1440                         return (ENXIO);
1441                 }
1442                 free(type, M_XENSTORE);
1443         }
1444
1445         device_set_desc(dev, "Virtual Block Device");
1446         device_quiet(dev);
1447         return (0);
1448 }
1449
1450 /*
1451  * Setup supplies the backend dir, virtual device.  We place an event
1452  * channel and shared frame entries.  We watch backend to wait if it's
1453  * ok.
1454  */
1455 static int
1456 xbd_attach(device_t dev)
1457 {
1458         struct xbd_softc *sc;
1459         const char *name;
1460         uint32_t vdevice;
1461         int error;
1462         int i;
1463         int unit;
1464
1465         /* FIXME: Use dynamic device id if this is not set. */
1466         error = xs_scanf(XST_NIL, xenbus_get_node(dev),
1467             "virtual-device", NULL, "%" PRIu32, &vdevice);
1468         if (error)
1469                 error = xs_scanf(XST_NIL, xenbus_get_node(dev),
1470                     "virtual-device-ext", NULL, "%" PRIu32, &vdevice);
1471         if (error) {
1472                 xenbus_dev_fatal(dev, error, "reading virtual-device");
1473                 device_printf(dev, "Couldn't determine virtual device.\n");
1474                 return (error);
1475         }
1476
1477         xbd_vdevice_to_unit(vdevice, &unit, &name);
1478         if (!strcmp(name, "xbd"))
1479                 device_set_unit(dev, unit);
1480
1481         sc = device_get_softc(dev);
1482         mtx_init(&sc->xbd_io_lock, "blkfront i/o lock", NULL, MTX_DEF);
1483         xbd_initqs(sc);
1484         for (i = 0; i < XBD_MAX_RING_PAGES; i++)
1485                 sc->xbd_ring_ref[i] = GRANT_REF_INVALID;
1486
1487         sc->xbd_dev = dev;
1488         sc->xbd_vdevice = vdevice;
1489         sc->xbd_state = XBD_STATE_DISCONNECTED;
1490
1491         xbd_setup_sysctl(sc);
1492
1493         /* Wait for backend device to publish its protocol capabilities. */
1494         xenbus_set_state(dev, XenbusStateInitialising);
1495
1496         return (0);
1497 }
1498
1499 static int
1500 xbd_detach(device_t dev)
1501 {
1502         struct xbd_softc *sc = device_get_softc(dev);
1503
1504         DPRINTK("%s: %s removed\n", __func__, xenbus_get_node(dev));
1505
1506         xbd_free(sc);
1507         mtx_destroy(&sc->xbd_io_lock);
1508
1509         return 0;
1510 }
1511
1512 static int
1513 xbd_suspend(device_t dev)
1514 {
1515         struct xbd_softc *sc = device_get_softc(dev);
1516         int retval;
1517         int saved_state;
1518
1519         /* Prevent new requests being issued until we fix things up. */
1520         mtx_lock(&sc->xbd_io_lock);
1521         saved_state = sc->xbd_state;
1522         sc->xbd_state = XBD_STATE_SUSPENDED;
1523
1524         /* Wait for outstanding I/O to drain. */
1525         retval = 0;
1526         while (xbd_queue_length(sc, XBD_Q_BUSY) != 0) {
1527                 if (msleep(&sc->xbd_cm_q[XBD_Q_BUSY], &sc->xbd_io_lock,
1528                     PRIBIO, "blkf_susp", 30 * hz) == EWOULDBLOCK) {
1529                         retval = EBUSY;
1530                         break;
1531                 }
1532         }
1533         mtx_unlock(&sc->xbd_io_lock);
1534
1535         if (retval != 0)
1536                 sc->xbd_state = saved_state;
1537
1538         return (retval);
1539 }
1540
1541 static int
1542 xbd_resume(device_t dev)
1543 {
1544         struct xbd_softc *sc = device_get_softc(dev);
1545
1546         if (xen_suspend_cancelled) {
1547                 sc->xbd_state = XBD_STATE_CONNECTED;
1548                 return (0);
1549         }
1550
1551         DPRINTK("xbd_resume: %s\n", xenbus_get_node(dev));
1552
1553         xbd_free(sc);
1554         xbd_initialize(sc);
1555         return (0);
1556 }
1557
1558 /**
1559  * Callback received when the backend's state changes.
1560  */
1561 static void
1562 xbd_backend_changed(device_t dev, XenbusState backend_state)
1563 {
1564         struct xbd_softc *sc = device_get_softc(dev);
1565
1566         DPRINTK("backend_state=%d\n", backend_state);
1567
1568         switch (backend_state) {
1569         case XenbusStateUnknown:
1570         case XenbusStateInitialising:
1571         case XenbusStateReconfigured:
1572         case XenbusStateReconfiguring:
1573         case XenbusStateClosed:
1574                 break;
1575
1576         case XenbusStateInitWait:
1577         case XenbusStateInitialised:
1578                 xbd_initialize(sc);
1579                 break;
1580
1581         case XenbusStateConnected:
1582                 xbd_initialize(sc);
1583                 xbd_connect(sc);
1584                 break;
1585
1586         case XenbusStateClosing:
1587                 if (sc->xbd_users > 0) {
1588                         device_printf(dev, "detaching with pending users\n");
1589                         KASSERT(sc->xbd_disk != NULL,
1590                             ("NULL disk with pending users\n"));
1591                         disk_gone(sc->xbd_disk);
1592                 } else {
1593                         xbd_closing(dev);
1594                 }
1595                 break;
1596         }
1597 }
1598
1599 /*---------------------------- NewBus Registration ---------------------------*/
1600 static device_method_t xbd_methods[] = {
1601         /* Device interface */
1602         DEVMETHOD(device_probe,         xbd_probe),
1603         DEVMETHOD(device_attach,        xbd_attach),
1604         DEVMETHOD(device_detach,        xbd_detach),
1605         DEVMETHOD(device_shutdown,      bus_generic_shutdown),
1606         DEVMETHOD(device_suspend,       xbd_suspend),
1607         DEVMETHOD(device_resume,        xbd_resume),
1608
1609         /* Xenbus interface */
1610         DEVMETHOD(xenbus_otherend_changed, xbd_backend_changed),
1611
1612         { 0, 0 }
1613 };
1614
1615 static driver_t xbd_driver = {
1616         "xbd",
1617         xbd_methods,
1618         sizeof(struct xbd_softc),
1619 };
1620 devclass_t xbd_devclass;
1621
1622 DRIVER_MODULE(xbd, xenbusb_front, xbd_driver, xbd_devclass, 0, 0);