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