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