sys/dev/xen/blkfront/blkfront.c

   1 /*
   2  * XenBSD block device driver
   3  *
   4  * Copyright (c) 2009 Scott Long, Yahoo!
   5  * Copyright (c) 2009 Frank Suchomel, Citrix
   6  * Copyright (c) 2009 Doug F. Rabson, Citrix
   7  * Copyright (c) 2005 Kip Macy
   8  * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
   9  * Modifications by Mark A. Williamson are (c) Intel Research Cambridge
  10  *
  11  *
  12  * Permission is hereby granted, free of charge, to any person obtaining a copy
  13  * of this software and associated documentation files (the "Software"), to
  14  * deal in the Software without restriction, including without limitation the
  15  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  16  * sell copies of the Software, and to permit persons to whom the Software is
  17  * furnished to do so, subject to the following conditions:
  18  *
  19  * The above copyright notice and this permission notice shall be included in
  20  * all copies or substantial portions of the Software.
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  26  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  27  * DEALINGS IN THE SOFTWARE.
  28  */
  29
  30 #include <sys/cdefs.h>
  31 __FBSDID("$FreeBSD$");
  32
  33 #include <sys/param.h>
  34 #include <sys/systm.h>
  35 #include <sys/malloc.h>
  36 #include <sys/kernel.h>
  37 #include <vm/vm.h>
  38 #include <vm/pmap.h>
  39
  40 #include <sys/bio.h>
  41 #include <sys/bus.h>
  42 #include <sys/conf.h>
  43 #include <sys/module.h>
  44 #include <sys/sysctl.h>
  45
  46 #include <machine/bus.h>
  47 #include <sys/rman.h>
  48 #include <machine/resource.h>
  49 #include <machine/intr_machdep.h>
  50 #include <machine/vmparam.h>
  51 #include <sys/bus_dma.h>
  52
  53 #include <machine/_inttypes.h>
  54 #include <machine/xen/xen-os.h>
  55 #include <machine/xen/xenvar.h>
  56 #include <machine/xen/xenfunc.h>
  57
  58 #include <xen/hypervisor.h>
  59 #include <xen/xen_intr.h>
  60 #include <xen/evtchn.h>
  61 #include <xen/gnttab.h>
  62 #include <xen/interface/grant_table.h>
  63 #include <xen/interface/io/protocols.h>
  64 #include <xen/xenbus/xenbusvar.h>
  65
  66 #include <geom/geom_disk.h>
  67
  68 #include <dev/xen/blkfront/block.h>
  69
  70 #include "xenbus_if.h"
  71
  72 /* prototypes */
  73 static void xb_free_command(struct xb_command *cm);
  74 static void xb_startio(struct xb_softc *sc);
  75 static void blkfront_connect(struct xb_softc *);
  76 static void blkfront_closing(device_t);
  77 static int blkfront_detach(device_t);
  78 static int setup_blkring(struct xb_softc *);
  79 static void blkif_int(void *);
  80 static void blkfront_initialize(struct xb_softc *);
  81 static int blkif_completion(struct xb_command *);
  82 static void blkif_free(struct xb_softc *);
  83 static void blkif_queue_cb(void *, bus_dma_segment_t *, int, int);
  84
  85 static MALLOC_DEFINE(M_XENBLOCKFRONT, "xbd", "Xen Block Front driver data");
  86
  87 #define GRANT_INVALID_REF 0
  88
  89 /* Control whether runtime update of vbds is enabled. */
  90 #define ENABLE_VBD_UPDATE 0
  91
  92 #if ENABLE_VBD_UPDATE
  93 static void vbd_update(void);
  94 #endif
  95
  96 #define BLKIF_STATE_DISCONNECTED 0
  97 #define BLKIF_STATE_CONNECTED    1
  98 #define BLKIF_STATE_SUSPENDED    2
  99
 100 #ifdef notyet
 101 static char *blkif_state_name[] = {
 102         [BLKIF_STATE_DISCONNECTED] = "disconnected",
 103         [BLKIF_STATE_CONNECTED]    = "connected",
 104         [BLKIF_STATE_SUSPENDED]    = "closed",
 105 };
 106
 107 static char * blkif_status_name[] = {
 108         [BLKIF_INTERFACE_STATUS_CLOSED]       = "closed",
 109         [BLKIF_INTERFACE_STATUS_DISCONNECTED] = "disconnected",
 110         [BLKIF_INTERFACE_STATUS_CONNECTED]    = "connected",
 111         [BLKIF_INTERFACE_STATUS_CHANGED]      = "changed",
 112 };
 113 #endif
 114
 115 #if 0
 116 #define DPRINTK(fmt, args...) printf("[XEN] %s:%d: " fmt ".\n", __func__, __LINE__, ##args)
 117 #else
 118 #define DPRINTK(fmt, args...)
 119 #endif
 120
 121 static int blkif_open(struct disk *dp);
 122 static int blkif_close(struct disk *dp);
 123 static int blkif_ioctl(struct disk *dp, u_long cmd, void *addr, int flag, struct thread *td);
 124 static int blkif_queue_request(struct xb_softc *sc, struct xb_command *cm);
 125 static void xb_strategy(struct bio *bp);
 126
 127 // In order to quiesce the device during kernel dumps, outstanding requests to
 128 // DOM0 for disk reads/writes need to be accounted for.
 129 static  int     xb_dump(void *, void *, vm_offset_t, off_t, size_t);
 130
 131 /* XXX move to xb_vbd.c when VBD update support is added */
 132 #define MAX_VBDS 64
 133
 134 #define XBD_SECTOR_SIZE         512     /* XXX: assume for now */
 135 #define XBD_SECTOR_SHFT         9
 136
 137 /*
 138  * Translate Linux major/minor to an appropriate name and unit
 139  * number. For HVM guests, this allows us to use the same drive names
 140  * with blkfront as the emulated drives, easing transition slightly.
 141  */
 142 static void
 143 blkfront_vdevice_to_unit(uint32_t vdevice, int *unit, const char **name)
 144 {
 145         static struct vdev_info {
 146                 int major;
 147                 int shift;
 148                 int base;
 149                 const char *name;
 150         } info[] = {
 151                 {3,     6,      0,      "ada"}, /* ide0 */
 152                 {22,    6,      2,      "ada"}, /* ide1 */
 153                 {33,    6,      4,      "ada"}, /* ide2 */
 154                 {34,    6,      6,      "ada"}, /* ide3 */
 155                 {56,    6,      8,      "ada"}, /* ide4 */
 156                 {57,    6,      10,     "ada"}, /* ide5 */
 157                 {88,    6,      12,     "ada"}, /* ide6 */
 158                 {89,    6,      14,     "ada"}, /* ide7 */
 159                 {90,    6,      16,     "ada"}, /* ide8 */
 160                 {91,    6,      18,     "ada"}, /* ide9 */
 161
 162                 {8,     4,      0,      "da"},  /* scsi disk0 */
 163                 {65,    4,      16,     "da"},  /* scsi disk1 */
 164                 {66,    4,      32,     "da"},  /* scsi disk2 */
 165                 {67,    4,      48,     "da"},  /* scsi disk3 */
 166                 {68,    4,      64,     "da"},  /* scsi disk4 */
 167                 {69,    4,      80,     "da"},  /* scsi disk5 */
 168                 {70,    4,      96,     "da"},  /* scsi disk6 */
 169                 {71,    4,      112,    "da"},  /* scsi disk7 */
 170                 {128,   4,      128,    "da"},  /* scsi disk8 */
 171                 {129,   4,      144,    "da"},  /* scsi disk9 */
 172                 {130,   4,      160,    "da"},  /* scsi disk10 */
 173                 {131,   4,      176,    "da"},  /* scsi disk11 */
 174                 {132,   4,      192,    "da"},  /* scsi disk12 */
 175                 {133,   4,      208,    "da"},  /* scsi disk13 */
 176                 {134,   4,      224,    "da"},  /* scsi disk14 */
 177                 {135,   4,      240,    "da"},  /* scsi disk15 */
 178
 179                 {202,   4,      0,      "xbd"}, /* xbd */
 180
 181                 {0,     0,      0,      NULL},
 182         };
 183         int major = vdevice >> 8;
 184         int minor = vdevice & 0xff;
 185         int i;
 186
 187         if (vdevice & (1 << 28)) {
 188                 *unit = (vdevice & ((1 << 28) - 1)) >> 8;
 189                 *name = "xbd";
 190                 return;
 191         }
 192
 193         for (i = 0; info[i].major; i++) {
 194                 if (info[i].major == major) {
 195                         *unit = info[i].base + (minor >> info[i].shift);
 196                         *name = info[i].name;
 197                         return;
 198                 }
 199         }
 200
 201         *unit = minor >> 4;
 202         *name = "xbd";
 203 }
 204
 205 int
 206 xlvbd_add(struct xb_softc *sc, blkif_sector_t sectors,
 207     int vdevice, uint16_t vdisk_info, unsigned long sector_size)
 208 {
 209         int     unit, error = 0;
 210         const char *name;
 211
 212         blkfront_vdevice_to_unit(vdevice, &unit, &name);
 213
 214         sc->xb_unit = unit;
 215
 216         if (strcmp(name, "xbd"))
 217                 device_printf(sc->xb_dev, "attaching as %s%d\n", name, unit);
 218
 219         sc->xb_disk = disk_alloc();
 220         sc->xb_disk->d_unit = sc->xb_unit;
 221         sc->xb_disk->d_open = blkif_open;
 222         sc->xb_disk->d_close = blkif_close;
 223         sc->xb_disk->d_ioctl = blkif_ioctl;
 224         sc->xb_disk->d_strategy = xb_strategy;
 225         sc->xb_disk->d_dump = xb_dump;
 226         sc->xb_disk->d_name = name;
 227         sc->xb_disk->d_drv1 = sc;
 228         sc->xb_disk->d_sectorsize = sector_size;
 229
 230         sc->xb_disk->d_mediasize = sectors * sector_size;
 231         sc->xb_disk->d_maxsize = sc->max_request_size;
 232         sc->xb_disk->d_flags = 0;
 233         disk_create(sc->xb_disk, DISK_VERSION);
 234
 235         return error;
 236 }
 237
 238 /************************ end VBD support *****************/
 239
 240 /*
 241  * Read/write routine for a buffer.  Finds the proper unit, place it on
 242  * the sortq and kick the controller.
 243  */
 244 static void
 245 xb_strategy(struct bio *bp)
 246 {
 247         struct xb_softc *sc = (struct xb_softc *)bp->bio_disk->d_drv1;
 248
 249         /* bogus disk? */
 250         if (sc == NULL) {
 251                 bp->bio_error = EINVAL;
 252                 bp->bio_flags |= BIO_ERROR;
 253                 bp->bio_resid = bp->bio_bcount;
 254                 biodone(bp);
 255                 return;
 256         }
 257
 258         /*
 259          * Place it in the queue of disk activities for this disk
 260          */
 261         mtx_lock(&sc->xb_io_lock);
 262
 263         xb_enqueue_bio(sc, bp);
 264         xb_startio(sc);
 265
 266         mtx_unlock(&sc->xb_io_lock);
 267         return;
 268 }
 269
 270 static void
 271 xb_bio_complete(struct xb_softc *sc, struct xb_command *cm)
 272 {
 273         struct bio *bp;
 274
 275         bp = cm->bp;
 276
 277         if ( unlikely(cm->status != BLKIF_RSP_OKAY) ) {
 278                 disk_err(bp, "disk error" , -1, 0);
 279                 printf(" status: %x\n", cm->status);
 280                 bp->bio_flags |= BIO_ERROR;
 281         }
 282
 283         if (bp->bio_flags & BIO_ERROR)
 284                 bp->bio_error = EIO;
 285         else
 286                 bp->bio_resid = 0;
 287
 288         xb_free_command(cm);
 289         biodone(bp);
 290 }
 291
 292 // Quiesce the disk writes for a dump file before allowing the next buffer.
 293 static void
 294 xb_quiesce(struct xb_softc *sc)
 295 {
 296         int             mtd;
 297
 298         // While there are outstanding requests
 299         while (!TAILQ_EMPTY(&sc->cm_busy)) {
 300                 RING_FINAL_CHECK_FOR_RESPONSES(&sc->ring, mtd);
 301                 if (mtd) {
 302                         /* Recieved request completions, update queue. */
 303                         blkif_int(sc);
 304                 }
 305                 if (!TAILQ_EMPTY(&sc->cm_busy)) {
 306                         /*
 307                          * Still pending requests, wait for the disk i/o
 308                          * to complete.
 309                          */
 310                         HYPERVISOR_yield();
 311                 }
 312         }
 313 }
 314
 315 /* Kernel dump function for a paravirtualized disk device */
 316 static void
 317 xb_dump_complete(struct xb_command *cm)
 318 {
 319
 320         xb_enqueue_complete(cm);
 321 }
 322
 323 static int
 324 xb_dump(void *arg, void *virtual, vm_offset_t physical, off_t offset,
 325         size_t length)
 326 {
 327         struct  disk    *dp = arg;
 328         struct xb_softc *sc = (struct xb_softc *) dp->d_drv1;
 329         struct xb_command *cm;
 330         size_t          chunk;
 331         int             sbp;
 332         int             rc = 0;
 333
 334         if (length <= 0)
 335                 return (rc);
 336
 337         xb_quiesce(sc); /* All quiet on the western front. */
 338
 339         /*
 340          * If this lock is held, then this module is failing, and a
 341          * successful kernel dump is highly unlikely anyway.
 342          */
 343         mtx_lock(&sc->xb_io_lock);
 344
 345         /* Split the 64KB block as needed */
 346         for (sbp=0; length > 0; sbp++) {
 347                 cm = xb_dequeue_free(sc);
 348                 if (cm == NULL) {
 349                         mtx_unlock(&sc->xb_io_lock);
 350                         device_printf(sc->xb_dev, "dump: no more commands?\n");
 351                         return (EBUSY);
 352                 }
 353
 354                 if (gnttab_alloc_grant_references(sc->max_request_segments,
 355                                                   &cm->gref_head) != 0) {
 356                         xb_free_command(cm);
 357                         mtx_unlock(&sc->xb_io_lock);
 358                         device_printf(sc->xb_dev, "no more grant allocs?\n");
 359                         return (EBUSY);
 360                 }
 361
 362                 chunk = length > sc->max_request_size
 363                       ? sc->max_request_size : length;
 364                 cm->data = virtual;
 365                 cm->datalen = chunk;
 366                 cm->operation = BLKIF_OP_WRITE;
 367                 cm->sector_number = offset / dp->d_sectorsize;
 368                 cm->cm_complete = xb_dump_complete;
 369
 370                 xb_enqueue_ready(cm);
 371
 372                 length -= chunk;
 373                 offset += chunk;
 374                 virtual = (char *) virtual + chunk;
 375         }
 376
 377         /* Tell DOM0 to do the I/O */
 378         xb_startio(sc);
 379         mtx_unlock(&sc->xb_io_lock);
 380
 381         /* Poll for the completion. */
 382         xb_quiesce(sc); /* All quite on the eastern front */
 383
 384         /* If there were any errors, bail out... */
 385         while ((cm = xb_dequeue_complete(sc)) != NULL) {
 386                 if (cm->status != BLKIF_RSP_OKAY) {
 387                         device_printf(sc->xb_dev,
 388                             "Dump I/O failed at sector %jd\n",
 389                             cm->sector_number);
 390                         rc = EIO;
 391                 }
 392                 xb_free_command(cm);
 393         }
 394
 395         return (rc);
 396 }
 397
 398
 399 static int
 400 blkfront_probe(device_t dev)
 401 {
 402 #ifdef XENHVM
 403         int error;
 404         char *type;
 405 #endif
 406
 407         if (strcmp(xenbus_get_type(dev), "vbd") != 0)
 408                 return (ENXIO);
 409
 410 #ifdef XENHVM
 411         /*
 412          * When running in an HVM domain, IDE disk emulation is
 413          * disabled early in boot so that native drivers will
 414          * not see emulated hardware.  However, CDROM device
 415          * emulation cannot be disabled.
 416          *
 417          * Through use of FreeBSD's vm_guest and xen_hvm_domain()
 418          * APIs, we could modify the native CDROM driver to fail its
 419          * probe when running under Xen.  Unfortunatlely, the PV
 420          * CDROM support in XenServer (up through at least version
 421          * 6.2) isn't functional, so we instead rely on the emulated
 422          * CDROM instance, and fail to attach the PV one here in
 423          * the blkfront driver.
 424          */
 425         error = xs_read(XST_NIL, xenbus_get_node(dev),
 426             "device-type", NULL, (void **) &type);
 427         if (error)
 428                 return (ENXIO);
 429
 430         if (strncmp(type, "cdrom", 5) == 0) {
 431                 free(type, M_XENSTORE);
 432                 return (ENXIO);
 433         }
 434         free(type, M_XENSTORE);
 435 #endif
 436
 437         device_set_desc(dev, "Virtual Block Device");
 438         device_quiet(dev);
 439         return (0);
 440 }
 441
 442 static void
 443 xb_setup_sysctl(struct xb_softc *xb)
 444 {
 445         struct sysctl_ctx_list *sysctl_ctx = NULL;
 446         struct sysctl_oid      *sysctl_tree = NULL;
 447
 448         sysctl_ctx = device_get_sysctl_ctx(xb->xb_dev);
 449         if (sysctl_ctx == NULL)
 450                 return;
 451
 452         sysctl_tree = device_get_sysctl_tree(xb->xb_dev);
 453         if (sysctl_tree == NULL)
 454                 return;
 455
 456         SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
 457                         "max_requests", CTLFLAG_RD, &xb->max_requests, -1,
 458                         "maximum outstanding requests (negotiated)");
 459
 460         SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
 461                         "max_request_segments", CTLFLAG_RD,
 462                         &xb->max_request_segments, 0,
 463                         "maximum number of pages per requests (negotiated)");
 464
 465         SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
 466                         "max_request_size", CTLFLAG_RD,
 467                         &xb->max_request_size, 0,
 468                         "maximum size in bytes of a request (negotiated)");
 469
 470         SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
 471                         "ring_pages", CTLFLAG_RD,
 472                         &xb->ring_pages, 0,
 473                         "communication channel pages (negotiated)");
 474 }
 475
 476 /*
 477  * Setup supplies the backend dir, virtual device.  We place an event
 478  * channel and shared frame entries.  We watch backend to wait if it's
 479  * ok.
 480  */
 481 static int
 482 blkfront_attach(device_t dev)
 483 {
 484         struct xb_softc *sc;
 485         const char *name;
 486         uint32_t vdevice;
 487         int error;
 488         int i;
 489         int unit;
 490
 491         /* FIXME: Use dynamic device id if this is not set. */
 492         error = xs_scanf(XST_NIL, xenbus_get_node(dev),
 493             "virtual-device", NULL, "%" PRIu32, &vdevice);
 494         if (error) {
 495                 xenbus_dev_fatal(dev, error, "reading virtual-device");
 496                 device_printf(dev, "Couldn't determine virtual device.\n");
 497                 return (error);
 498         }
 499
 500         blkfront_vdevice_to_unit(vdevice, &unit, &name);
 501         if (!strcmp(name, "xbd"))
 502                 device_set_unit(dev, unit);
 503
 504         sc = device_get_softc(dev);
 505         mtx_init(&sc->xb_io_lock, "blkfront i/o lock", NULL, MTX_DEF);
 506         xb_initq_free(sc);
 507         xb_initq_busy(sc);
 508         xb_initq_ready(sc);
 509         xb_initq_complete(sc);
 510         xb_initq_bio(sc);
 511         for (i = 0; i < XBF_MAX_RING_PAGES; i++)
 512                 sc->ring_ref[i] = GRANT_INVALID_REF;
 513
 514         sc->xb_dev = dev;
 515         sc->vdevice = vdevice;
 516         sc->connected = BLKIF_STATE_DISCONNECTED;
 517
 518         xb_setup_sysctl(sc);
 519
 520         /* Wait for backend device to publish its protocol capabilities. */
 521         xenbus_set_state(dev, XenbusStateInitialising);
 522
 523         return (0);
 524 }
 525
 526 static int
 527 blkfront_suspend(device_t dev)
 528 {
 529         struct xb_softc *sc = device_get_softc(dev);
 530         int retval;
 531         int saved_state;
 532
 533         /* Prevent new requests being issued until we fix things up. */
 534         mtx_lock(&sc->xb_io_lock);
 535         saved_state = sc->connected;
 536         sc->connected = BLKIF_STATE_SUSPENDED;
 537
 538         /* Wait for outstanding I/O to drain. */
 539         retval = 0;
 540         while (TAILQ_EMPTY(&sc->cm_busy) == 0) {
 541                 if (msleep(&sc->cm_busy, &sc->xb_io_lock,
 542                            PRIBIO, "blkf_susp", 30 * hz) == EWOULDBLOCK) {
 543                         retval = EBUSY;
 544                         break;
 545                 }
 546         }
 547         mtx_unlock(&sc->xb_io_lock);
 548
 549         if (retval != 0)
 550                 sc->connected = saved_state;
 551
 552         return (retval);
 553 }
 554
 555 static int
 556 blkfront_resume(device_t dev)
 557 {
 558         struct xb_softc *sc = device_get_softc(dev);
 559
 560         DPRINTK("blkfront_resume: %s\n", xenbus_get_node(dev));
 561
 562         blkif_free(sc);
 563         blkfront_initialize(sc);
 564         return (0);
 565 }
 566
 567 static void
 568 blkfront_initialize(struct xb_softc *sc)
 569 {
 570         const char *otherend_path;
 571         const char *node_path;
 572         uint32_t max_ring_page_order;
 573         int error;
 574         int i;
 575
 576         if (xenbus_get_state(sc->xb_dev) != XenbusStateInitialising) {
 577                 /* Initialization has already been performed. */
 578                 return;
 579         }
 580
 581         /*
 582          * Protocol defaults valid even if negotiation for a
 583          * setting fails.
 584          */
 585         max_ring_page_order = 0;
 586         sc->ring_pages = 1;
 587         sc->max_request_segments = BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK;
 588         sc->max_request_size = XBF_SEGS_TO_SIZE(sc->max_request_segments);
 589         sc->max_request_blocks = BLKIF_SEGS_TO_BLOCKS(sc->max_request_segments);
 590
 591         /*
 592          * Protocol negotiation.
 593          *
 594          * \note xs_gather() returns on the first encountered error, so
 595          *       we must use independant calls in order to guarantee
 596          *       we don't miss information in a sparsly populated back-end
 597          *       tree.
 598          *
 599          * \note xs_scanf() does not update variables for unmatched
 600          *       fields.
 601          */
 602         otherend_path = xenbus_get_otherend_path(sc->xb_dev);
 603         node_path = xenbus_get_node(sc->xb_dev);
 604
 605         /* Support both backend schemes for relaying ring page limits. */
 606         (void)xs_scanf(XST_NIL, otherend_path,
 607                        "max-ring-page-order", NULL, "%" PRIu32,
 608                        &max_ring_page_order);
 609         sc->ring_pages = 1 << max_ring_page_order;
 610         (void)xs_scanf(XST_NIL, otherend_path,
 611                        "max-ring-pages", NULL, "%" PRIu32,
 612                        &sc->ring_pages);
 613         if (sc->ring_pages < 1)
 614                 sc->ring_pages = 1;
 615
 616         sc->max_requests = BLKIF_MAX_RING_REQUESTS(sc->ring_pages * PAGE_SIZE);
 617         (void)xs_scanf(XST_NIL, otherend_path,
 618                        "max-requests", NULL, "%" PRIu32,
 619                        &sc->max_requests);
 620
 621         (void)xs_scanf(XST_NIL, otherend_path,
 622                        "max-request-segments", NULL, "%" PRIu32,
 623                        &sc->max_request_segments);
 624
 625         (void)xs_scanf(XST_NIL, otherend_path,
 626                        "max-request-size", NULL, "%" PRIu32,
 627                        &sc->max_request_size);
 628
 629         if (sc->ring_pages > XBF_MAX_RING_PAGES) {
 630                 device_printf(sc->xb_dev, "Back-end specified ring-pages of "
 631                               "%u limited to front-end limit of %zu.\n",
 632                               sc->ring_pages, XBF_MAX_RING_PAGES);
 633                 sc->ring_pages = XBF_MAX_RING_PAGES;
 634         }
 635
 636         if (powerof2(sc->ring_pages) == 0) {
 637                 uint32_t new_page_limit;
 638
 639                 new_page_limit = 0x01 << (fls(sc->ring_pages) - 1);
 640                 device_printf(sc->xb_dev, "Back-end specified ring-pages of "
 641                               "%u is not a power of 2. Limited to %u.\n",
 642                               sc->ring_pages, new_page_limit);
 643                 sc->ring_pages = new_page_limit;
 644         }
 645
 646         if (sc->max_requests > XBF_MAX_REQUESTS) {
 647                 device_printf(sc->xb_dev, "Back-end specified max_requests of "
 648                               "%u limited to front-end limit of %u.\n",
 649                               sc->max_requests, XBF_MAX_REQUESTS);
 650                 sc->max_requests = XBF_MAX_REQUESTS;
 651         }
 652
 653         if (sc->max_request_segments > XBF_MAX_SEGMENTS_PER_REQUEST) {
 654                 device_printf(sc->xb_dev, "Back-end specified "
 655                               "max_request_segments of %u limited to "
 656                               "front-end limit of %u.\n",
 657                               sc->max_request_segments,
 658                               XBF_MAX_SEGMENTS_PER_REQUEST);
 659                 sc->max_request_segments = XBF_MAX_SEGMENTS_PER_REQUEST;
 660         }
 661
 662         if (sc->max_request_size > XBF_MAX_REQUEST_SIZE) {
 663                 device_printf(sc->xb_dev, "Back-end specified "
 664                               "max_request_size of %u limited to front-end "
 665                               "limit of %u.\n", sc->max_request_size,
 666                               XBF_MAX_REQUEST_SIZE);
 667                 sc->max_request_size = XBF_MAX_REQUEST_SIZE;
 668         }
 669
 670         if (sc->max_request_size > XBF_SEGS_TO_SIZE(sc->max_request_segments)) {
 671                 device_printf(sc->xb_dev, "Back-end specified "
 672                               "max_request_size of %u limited to front-end "
 673                               "limit of %u.  (Too few segments.)\n",
 674                               sc->max_request_size,
 675                               XBF_SEGS_TO_SIZE(sc->max_request_segments));
 676                 sc->max_request_size =
 677                     XBF_SEGS_TO_SIZE(sc->max_request_segments);
 678         }
 679
 680         sc->max_request_blocks = BLKIF_SEGS_TO_BLOCKS(sc->max_request_segments);
 681
 682         /* Allocate datastructures based on negotiated values. */
 683         error = bus_dma_tag_create(bus_get_dma_tag(sc->xb_dev), /* parent */
 684                                    512, PAGE_SIZE,      /* algnmnt, boundary */
 685                                    BUS_SPACE_MAXADDR,   /* lowaddr */
 686                                    BUS_SPACE_MAXADDR,   /* highaddr */
 687                                    NULL, NULL,          /* filter, filterarg */
 688                                    sc->max_request_size,
 689                                    sc->max_request_segments,
 690                                    PAGE_SIZE,           /* maxsegsize */
 691                                    BUS_DMA_ALLOCNOW,    /* flags */
 692                                    busdma_lock_mutex,   /* lockfunc */
 693                                    &sc->xb_io_lock,     /* lockarg */
 694                                    &sc->xb_io_dmat);
 695         if (error != 0) {
 696                 xenbus_dev_fatal(sc->xb_dev, error,
 697                                  "Cannot allocate parent DMA tag\n");
 698                 return;
 699         }
 700
 701         /* Per-transaction data allocation. */
 702         sc->shadow = malloc(sizeof(*sc->shadow) * sc->max_requests,
 703                             M_XENBLOCKFRONT, M_NOWAIT|M_ZERO);
 704         if (sc->shadow == NULL) {
 705                 bus_dma_tag_destroy(sc->xb_io_dmat);
 706                 xenbus_dev_fatal(sc->xb_dev, error,
 707                                  "Cannot allocate request structures\n");
 708                 return;
 709         }
 710
 711         for (i = 0; i < sc->max_requests; i++) {
 712                 struct xb_command *cm;
 713
 714                 cm = &sc->shadow[i];
 715                 cm->sg_refs = malloc(sizeof(grant_ref_t)
 716                                    * sc->max_request_segments,
 717                                      M_XENBLOCKFRONT, M_NOWAIT);
 718                 if (cm->sg_refs == NULL)
 719                         break;
 720                 cm->id = i;
 721                 cm->cm_sc = sc;
 722                 if (bus_dmamap_create(sc->xb_io_dmat, 0, &cm->map) != 0)
 723                         break;
 724                 xb_free_command(cm);
 725         }
 726
 727         if (setup_blkring(sc) != 0)
 728                 return;
 729
 730         /* Support both backend schemes for relaying ring page limits. */
 731         if (sc->ring_pages > 1) {
 732                 error = xs_printf(XST_NIL, node_path,
 733                                  "num-ring-pages","%u", sc->ring_pages);
 734                 if (error) {
 735                         xenbus_dev_fatal(sc->xb_dev, error,
 736                                          "writing %s/num-ring-pages",
 737                                          node_path);
 738                         return;
 739                 }
 740
 741                 error = xs_printf(XST_NIL, node_path,
 742                                  "ring-page-order", "%u",
 743                                  fls(sc->ring_pages) - 1);
 744                 if (error) {
 745                         xenbus_dev_fatal(sc->xb_dev, error,
 746                                          "writing %s/ring-page-order",
 747                                          node_path);
 748                         return;
 749                 }
 750         }
 751
 752         error = xs_printf(XST_NIL, node_path,
 753                          "max-requests","%u", sc->max_requests);
 754         if (error) {
 755                 xenbus_dev_fatal(sc->xb_dev, error,
 756                                  "writing %s/max-requests",
 757                                  node_path);
 758                 return;
 759         }
 760
 761         error = xs_printf(XST_NIL, node_path,
 762                          "max-request-segments","%u", sc->max_request_segments);
 763         if (error) {
 764                 xenbus_dev_fatal(sc->xb_dev, error,
 765                                  "writing %s/max-request-segments",
 766                                  node_path);
 767                 return;
 768         }
 769
 770         error = xs_printf(XST_NIL, node_path,
 771                          "max-request-size","%u", sc->max_request_size);
 772         if (error) {
 773                 xenbus_dev_fatal(sc->xb_dev, error,
 774                                  "writing %s/max-request-size",
 775                                  node_path);
 776                 return;
 777         }
 778
 779         error = xs_printf(XST_NIL, node_path, "event-channel",
 780                           "%u", irq_to_evtchn_port(sc->irq));
 781         if (error) {
 782                 xenbus_dev_fatal(sc->xb_dev, error,
 783                                  "writing %s/event-channel",
 784                                  node_path);
 785                 return;
 786         }
 787
 788         error = xs_printf(XST_NIL, node_path,
 789                           "protocol", "%s", XEN_IO_PROTO_ABI_NATIVE);
 790         if (error) {
 791                 xenbus_dev_fatal(sc->xb_dev, error,
 792                                  "writing %s/protocol",
 793                                  node_path);
 794                 return;
 795         }
 796
 797         xenbus_set_state(sc->xb_dev, XenbusStateInitialised);
 798 }
 799
 800 static int
 801 setup_blkring(struct xb_softc *sc)
 802 {
 803         blkif_sring_t *sring;
 804         uintptr_t sring_page_addr;
 805         int error;
 806         int i;
 807
 808         sring = malloc(sc->ring_pages * PAGE_SIZE, M_XENBLOCKFRONT,
 809                        M_NOWAIT|M_ZERO);
 810         if (sring == NULL) {
 811                 xenbus_dev_fatal(sc->xb_dev, ENOMEM, "allocating shared ring");
 812                 return (ENOMEM);
 813         }
 814         SHARED_RING_INIT(sring);
 815         FRONT_RING_INIT(&sc->ring, sring, sc->ring_pages * PAGE_SIZE);
 816
 817         for (i = 0, sring_page_addr = (uintptr_t)sring;
 818              i < sc->ring_pages;
 819              i++, sring_page_addr += PAGE_SIZE) {
 820
 821                 error = xenbus_grant_ring(sc->xb_dev,
 822                     (vtomach(sring_page_addr) >> PAGE_SHIFT), &sc->ring_ref[i]);
 823                 if (error) {
 824                         xenbus_dev_fatal(sc->xb_dev, error,
 825                                          "granting ring_ref(%d)", i);
 826                         return (error);
 827                 }
 828         }
 829         if (sc->ring_pages == 1) {
 830                 error = xs_printf(XST_NIL, xenbus_get_node(sc->xb_dev),
 831                                   "ring-ref", "%u", sc->ring_ref[0]);
 832                 if (error) {
 833                         xenbus_dev_fatal(sc->xb_dev, error,
 834                                          "writing %s/ring-ref",
 835                                          xenbus_get_node(sc->xb_dev));
 836                         return (error);
 837                 }
 838         } else {
 839                 for (i = 0; i < sc->ring_pages; i++) {
 840                         char ring_ref_name[]= "ring_refXX";
 841
 842                         snprintf(ring_ref_name, sizeof(ring_ref_name),
 843                                  "ring-ref%u", i);
 844                         error = xs_printf(XST_NIL, xenbus_get_node(sc->xb_dev),
 845                                          ring_ref_name, "%u", sc->ring_ref[i]);
 846                         if (error) {
 847                                 xenbus_dev_fatal(sc->xb_dev, error,
 848                                                  "writing %s/%s",
 849                                                  xenbus_get_node(sc->xb_dev),
 850                                                  ring_ref_name);
 851                                 return (error);
 852                         }
 853                 }
 854         }
 855
 856         error = bind_listening_port_to_irqhandler(
 857             xenbus_get_otherend_id(sc->xb_dev),
 858             "xbd", (driver_intr_t *)blkif_int, sc,
 859             INTR_TYPE_BIO | INTR_MPSAFE, &sc->irq);
 860         if (error) {
 861                 xenbus_dev_fatal(sc->xb_dev, error,
 862                     "bind_evtchn_to_irqhandler failed");
 863                 return (error);
 864         }
 865
 866         return (0);
 867 }
 868
 869 /**
 870  * Callback received when the backend's state changes.
 871  */
 872 static void
 873 blkfront_backend_changed(device_t dev, XenbusState backend_state)
 874 {
 875         struct xb_softc *sc = device_get_softc(dev);
 876
 877         DPRINTK("backend_state=%d\n", backend_state);
 878
 879         switch (backend_state) {
 880         case XenbusStateUnknown:
 881         case XenbusStateInitialising:
 882         case XenbusStateReconfigured:
 883         case XenbusStateReconfiguring:
 884         case XenbusStateClosed:
 885                 break;
 886
 887         case XenbusStateInitWait:
 888         case XenbusStateInitialised:
 889                 blkfront_initialize(sc);
 890                 break;
 891
 892         case XenbusStateConnected:
 893                 blkfront_initialize(sc);
 894                 blkfront_connect(sc);
 895                 break;
 896
 897         case XenbusStateClosing:
 898                 if (sc->users > 0)
 899                         xenbus_dev_error(dev, -EBUSY,
 900                                          "Device in use; refusing to close");
 901                 else
 902                         blkfront_closing(dev);
 903                 break;
 904         }
 905 }
 906
 907 /*
 908 ** Invoked when the backend is finally 'ready' (and has published
 909 ** the details about the physical device - #sectors, size, etc).
 910 */
 911 static void
 912 blkfront_connect(struct xb_softc *sc)
 913 {
 914         device_t dev = sc->xb_dev;
 915         unsigned long sectors, sector_size;
 916         unsigned int binfo;
 917         int err, feature_barrier;
 918
 919         if( (sc->connected == BLKIF_STATE_CONNECTED) ||
 920             (sc->connected == BLKIF_STATE_SUSPENDED) )
 921                 return;
 922
 923         DPRINTK("blkfront.c:connect:%s.\n", xenbus_get_otherend_path(dev));
 924
 925         err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
 926                         "sectors", "%lu", &sectors,
 927                         "info", "%u", &binfo,
 928                         "sector-size", "%lu", &sector_size,
 929                         NULL);
 930         if (err) {
 931                 xenbus_dev_fatal(dev, err,
 932                     "reading backend fields at %s",
 933                     xenbus_get_otherend_path(dev));
 934                 return;
 935         }
 936         if ((sectors == 0) || (sector_size == 0)) {
 937                 xenbus_dev_fatal(dev, 0,
 938                     "invalid parameters from %s:"
 939                     " sectors = %lu, sector_size = %lu",
 940                     xenbus_get_otherend_path(dev),
 941                     sectors, sector_size);
 942                 return;
 943         }
 944         err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
 945                         "feature-barrier", "%d", &feature_barrier,
 946                         NULL);
 947         if (!err || feature_barrier)
 948                 sc->xb_flags |= XB_BARRIER;
 949
 950         if (sc->xb_disk == NULL) {
 951                 device_printf(dev, "%juMB <%s> at %s",
 952                     (uintmax_t) sectors / (1048576 / sector_size),
 953                     device_get_desc(dev),
 954                     xenbus_get_node(dev));
 955                 bus_print_child_footer(device_get_parent(dev), dev);
 956
 957                 xlvbd_add(sc, sectors, sc->vdevice, binfo, sector_size);
 958         }
 959
 960         (void)xenbus_set_state(dev, XenbusStateConnected);
 961
 962         /* Kick pending requests. */
 963         mtx_lock(&sc->xb_io_lock);
 964         sc->connected = BLKIF_STATE_CONNECTED;
 965         xb_startio(sc);
 966         sc->xb_flags |= XB_READY;
 967         mtx_unlock(&sc->xb_io_lock);
 968 }
 969
 970 /**
 971  * Handle the change of state of the backend to Closing.  We must delete our
 972  * device-layer structures now, to ensure that writes are flushed through to
 973  * the backend.  Once this is done, we can switch to Closed in
 974  * acknowledgement.
 975  */
 976 static void
 977 blkfront_closing(device_t dev)
 978 {
 979         struct xb_softc *sc = device_get_softc(dev);
 980
 981         xenbus_set_state(dev, XenbusStateClosing);
 982
 983         DPRINTK("blkfront_closing: %s removed\n", xenbus_get_node(dev));
 984
 985         if (sc->xb_disk != NULL) {
 986                 disk_destroy(sc->xb_disk);
 987                 sc->xb_disk = NULL;
 988         }
 989
 990         xenbus_set_state(dev, XenbusStateClosed);
 991 }
 992
 993
 994 static int
 995 blkfront_detach(device_t dev)
 996 {
 997         struct xb_softc *sc = device_get_softc(dev);
 998
 999         DPRINTK("blkfront_remove: %s removed\n", xenbus_get_node(dev));
1000
1001         blkif_free(sc);
1002         mtx_destroy(&sc->xb_io_lock);
1003
1004         return 0;
1005 }
1006
1007
1008 static inline void
1009 flush_requests(struct xb_softc *sc)
1010 {
1011         int notify;
1012
1013         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&sc->ring, notify);
1014
1015         if (notify)
1016                 notify_remote_via_irq(sc->irq);
1017 }
1018
1019 static void
1020 blkif_restart_queue_callback(void *arg)
1021 {
1022         struct xb_softc *sc = arg;
1023
1024         mtx_lock(&sc->xb_io_lock);
1025
1026         xb_startio(sc);
1027
1028         mtx_unlock(&sc->xb_io_lock);
1029 }
1030
1031 static int
1032 blkif_open(struct disk *dp)
1033 {
1034         struct xb_softc *sc = (struct xb_softc *)dp->d_drv1;
1035
1036         if (sc == NULL) {
1037                 printf("xb%d: not found", sc->xb_unit);
1038                 return (ENXIO);
1039         }
1040
1041         sc->xb_flags |= XB_OPEN;
1042         sc->users++;
1043         return (0);
1044 }
1045
1046 static int
1047 blkif_close(struct disk *dp)
1048 {
1049         struct xb_softc *sc = (struct xb_softc *)dp->d_drv1;
1050
1051         if (sc == NULL)
1052                 return (ENXIO);
1053         sc->xb_flags &= ~XB_OPEN;
1054         if (--(sc->users) == 0) {
1055                 /*
1056                  * Check whether we have been instructed to close.  We will
1057                  * have ignored this request initially, as the device was
1058                  * still mounted.
1059                  */
1060                 if (xenbus_get_otherend_state(sc->xb_dev) == XenbusStateClosing)
1061                         blkfront_closing(sc->xb_dev);
1062         }
1063         return (0);
1064 }
1065
1066 static int
1067 blkif_ioctl(struct disk *dp, u_long cmd, void *addr, int flag, struct thread *td)
1068 {
1069         struct xb_softc *sc = (struct xb_softc *)dp->d_drv1;
1070
1071         if (sc == NULL)
1072                 return (ENXIO);
1073
1074         return (ENOTTY);
1075 }
1076
1077 static void
1078 xb_free_command(struct xb_command *cm)
1079 {
1080
1081         KASSERT((cm->cm_flags & XB_ON_XBQ_MASK) == 0,
1082             ("Freeing command that is still on a queue\n"));
1083
1084         cm->cm_flags = 0;
1085         cm->bp = NULL;
1086         cm->cm_complete = NULL;
1087         xb_enqueue_free(cm);
1088 }
1089
1090 /*
1091  * blkif_queue_request
1092  *
1093  * request block io
1094  *
1095  * id: for guest use only.
1096  * operation: BLKIF_OP_{READ,WRITE,PROBE}
1097  * buffer: buffer to read/write into. this should be a
1098  *   virtual address in the guest os.
1099  */
1100 static struct xb_command *
1101 xb_bio_command(struct xb_softc *sc)
1102 {
1103         struct xb_command *cm;
1104         struct bio *bp;
1105
1106         if (unlikely(sc->connected != BLKIF_STATE_CONNECTED))
1107                 return (NULL);
1108
1109         bp = xb_dequeue_bio(sc);
1110         if (bp == NULL)
1111                 return (NULL);
1112
1113         if ((cm = xb_dequeue_free(sc)) == NULL) {
1114                 xb_requeue_bio(sc, bp);
1115                 return (NULL);
1116         }
1117
1118         if (gnttab_alloc_grant_references(sc->max_request_segments,
1119             &cm->gref_head) != 0) {
1120                 gnttab_request_free_callback(&sc->callback,
1121                         blkif_restart_queue_callback, sc,
1122                         sc->max_request_segments);
1123                 xb_requeue_bio(sc, bp);
1124                 xb_enqueue_free(cm);
1125                 sc->xb_flags |= XB_FROZEN;
1126                 return (NULL);
1127         }
1128
1129         cm->bp = bp;
1130         cm->data = bp->bio_data;
1131         cm->datalen = bp->bio_bcount;
1132         cm->operation = (bp->bio_cmd == BIO_READ) ? BLKIF_OP_READ :
1133             BLKIF_OP_WRITE;
1134         cm->sector_number = (blkif_sector_t)bp->bio_pblkno;
1135
1136         return (cm);
1137 }
1138
1139 static int
1140 blkif_queue_request(struct xb_softc *sc, struct xb_command *cm)
1141 {
1142         int     error;
1143
1144         error = bus_dmamap_load(sc->xb_io_dmat, cm->map, cm->data, cm->datalen,
1145             blkif_queue_cb, cm, 0);
1146         if (error == EINPROGRESS) {
1147                 printf("EINPROGRESS\n");
1148                 sc->xb_flags |= XB_FROZEN;
1149                 cm->cm_flags |= XB_CMD_FROZEN;
1150                 return (0);
1151         }
1152
1153         return (error);
1154 }
1155
1156 static void
1157 blkif_queue_cb(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
1158 {
1159         struct xb_softc *sc;
1160         struct xb_command *cm;
1161         blkif_request_t *ring_req;
1162         struct blkif_request_segment *sg;
1163         struct blkif_request_segment *last_block_sg;
1164         grant_ref_t *sg_ref;
1165         vm_paddr_t buffer_ma;
1166         uint64_t fsect, lsect;
1167         int ref;
1168         int op;
1169         int block_segs;
1170
1171         cm = arg;
1172         sc = cm->cm_sc;
1173
1174 //printf("%s: Start\n", __func__);
1175         if (error) {
1176                 printf("error %d in blkif_queue_cb\n", error);
1177                 cm->bp->bio_error = EIO;
1178                 biodone(cm->bp);
1179                 xb_free_command(cm);
1180                 return;
1181         }
1182
1183         /* Fill out a communications ring structure. */
1184         ring_req = RING_GET_REQUEST(&sc->ring, sc->ring.req_prod_pvt);
1185         sc->ring.req_prod_pvt++;
1186         ring_req->id = cm->id;
1187         ring_req->operation = cm->operation;
1188         ring_req->sector_number = cm->sector_number;
1189         ring_req->handle = (blkif_vdev_t)(uintptr_t)sc->xb_disk;
1190         ring_req->nr_segments = nsegs;
1191         cm->nseg = nsegs;
1192
1193         block_segs    = MIN(nsegs, BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK);
1194         sg            = ring_req->seg;
1195         last_block_sg = sg + block_segs;
1196         sg_ref        = cm->sg_refs;
1197
1198         while (1) {
1199
1200                 while (sg < last_block_sg) {
1201                         buffer_ma = segs->ds_addr;
1202                         fsect = (buffer_ma & PAGE_MASK) >> XBD_SECTOR_SHFT;
1203                         lsect = fsect + (segs->ds_len  >> XBD_SECTOR_SHFT) - 1;
1204
1205                         KASSERT(lsect <= 7, ("XEN disk driver data cannot "
1206                                 "cross a page boundary"));
1207
1208                         /* install a grant reference. */
1209                         ref = gnttab_claim_grant_reference(&cm->gref_head);
1210
1211                         /*
1212                          * GNTTAB_LIST_END == 0xffffffff, but it is private
1213                          * to gnttab.c.
1214                          */
1215                         KASSERT(ref != ~0, ("grant_reference failed"));
1216
1217                         gnttab_grant_foreign_access_ref(
1218                                 ref,
1219                                 xenbus_get_otherend_id(sc->xb_dev),
1220                                 buffer_ma >> PAGE_SHIFT,
1221                                 ring_req->operation == BLKIF_OP_WRITE);
1222
1223                         *sg_ref = ref;
1224                         *sg = (struct blkif_request_segment) {
1225                                 .gref       = ref,
1226                                 .first_sect = fsect,
1227                                 .last_sect  = lsect };
1228                         sg++;
1229                         sg_ref++;
1230                         segs++;
1231                         nsegs--;
1232                 }
1233                 block_segs = MIN(nsegs, BLKIF_MAX_SEGMENTS_PER_SEGMENT_BLOCK);
1234                 if (block_segs == 0)
1235                         break;
1236
1237                 sg = BLKRING_GET_SEG_BLOCK(&sc->ring, sc->ring.req_prod_pvt);
1238                 sc->ring.req_prod_pvt++;
1239                 last_block_sg = sg + block_segs;
1240         }
1241
1242         if (cm->operation == BLKIF_OP_READ)
1243                 op = BUS_DMASYNC_PREREAD;
1244         else if (cm->operation == BLKIF_OP_WRITE)
1245                 op = BUS_DMASYNC_PREWRITE;
1246         else
1247                 op = 0;
1248         bus_dmamap_sync(sc->xb_io_dmat, cm->map, op);
1249
1250         gnttab_free_grant_references(cm->gref_head);
1251
1252         xb_enqueue_busy(cm);
1253
1254         /*
1255          * This flag means that we're probably executing in the busdma swi
1256          * instead of in the startio context, so an explicit flush is needed.
1257          */
1258         if (cm->cm_flags & XB_CMD_FROZEN)
1259                 flush_requests(sc);
1260
1261 //printf("%s: Done\n", __func__);
1262         return;
1263 }
1264
1265 /*
1266  * Dequeue buffers and place them in the shared communication ring.
1267  * Return when no more requests can be accepted or all buffers have
1268  * been queued.
1269  *
1270  * Signal XEN once the ring has been filled out.
1271  */
1272 static void
1273 xb_startio(struct xb_softc *sc)
1274 {
1275         struct xb_command *cm;
1276         int error, queued = 0;
1277
1278         mtx_assert(&sc->xb_io_lock, MA_OWNED);
1279
1280         if (sc->connected != BLKIF_STATE_CONNECTED)
1281                 return;
1282
1283         while (RING_FREE_REQUESTS(&sc->ring) >= sc->max_request_blocks) {
1284                 if (sc->xb_flags & XB_FROZEN)
1285                         break;
1286
1287                 cm = xb_dequeue_ready(sc);
1288
1289                 if (cm == NULL)
1290                     cm = xb_bio_command(sc);
1291
1292                 if (cm == NULL)
1293                         break;
1294
1295                 if ((error = blkif_queue_request(sc, cm)) != 0) {
1296                         printf("blkif_queue_request returned %d\n", error);
1297                         break;
1298                 }
1299                 queued++;
1300         }
1301
1302         if (queued != 0)
1303                 flush_requests(sc);
1304 }
1305
1306 static void
1307 blkif_int(void *xsc)
1308 {
1309         struct xb_softc *sc = xsc;
1310         struct xb_command *cm;
1311         blkif_response_t *bret;
1312         RING_IDX i, rp;
1313         int op;
1314
1315         mtx_lock(&sc->xb_io_lock);
1316
1317         if (unlikely(sc->connected == BLKIF_STATE_DISCONNECTED)) {
1318                 mtx_unlock(&sc->xb_io_lock);
1319                 return;
1320         }
1321
1322  again:
1323         rp = sc->ring.sring->rsp_prod;
1324         rmb(); /* Ensure we see queued responses up to 'rp'. */
1325
1326         for (i = sc->ring.rsp_cons; i != rp;) {
1327                 bret = RING_GET_RESPONSE(&sc->ring, i);
1328                 cm   = &sc->shadow[bret->id];
1329
1330                 xb_remove_busy(cm);
1331                 i += blkif_completion(cm);
1332
1333                 if (cm->operation == BLKIF_OP_READ)
1334                         op = BUS_DMASYNC_POSTREAD;
1335                 else if (cm->operation == BLKIF_OP_WRITE)
1336                         op = BUS_DMASYNC_POSTWRITE;
1337                 else
1338                         op = 0;
1339                 bus_dmamap_sync(sc->xb_io_dmat, cm->map, op);
1340                 bus_dmamap_unload(sc->xb_io_dmat, cm->map);
1341
1342                 /*
1343                  * If commands are completing then resources are probably
1344                  * being freed as well.  It's a cheap assumption even when
1345                  * wrong.
1346                  */
1347                 sc->xb_flags &= ~XB_FROZEN;
1348
1349                 /*
1350                  * Directly call the i/o complete routine to save an
1351                  * an indirection in the common case.
1352                  */
1353                 cm->status = bret->status;
1354                 if (cm->bp)
1355                         xb_bio_complete(sc, cm);
1356                 else if (cm->cm_complete)
1357                         (cm->cm_complete)(cm);
1358                 else
1359                         xb_free_command(cm);
1360         }
1361
1362         sc->ring.rsp_cons = i;
1363
1364         if (i != sc->ring.req_prod_pvt) {
1365                 int more_to_do;
1366                 RING_FINAL_CHECK_FOR_RESPONSES(&sc->ring, more_to_do);
1367                 if (more_to_do)
1368                         goto again;
1369         } else {
1370                 sc->ring.sring->rsp_event = i + 1;
1371         }
1372
1373         xb_startio(sc);
1374
1375         if (unlikely(sc->connected == BLKIF_STATE_SUSPENDED))
1376                 wakeup(&sc->cm_busy);
1377
1378         mtx_unlock(&sc->xb_io_lock);
1379 }
1380
1381 static void
1382 blkif_free(struct xb_softc *sc)
1383 {
1384         uint8_t *sring_page_ptr;
1385         int i;
1386
1387         /* Prevent new requests being issued until we fix things up. */
1388         mtx_lock(&sc->xb_io_lock);
1389         sc->connected = BLKIF_STATE_DISCONNECTED;
1390         mtx_unlock(&sc->xb_io_lock);
1391
1392         /* Free resources associated with old device channel. */
1393         if (sc->ring.sring != NULL) {
1394                 sring_page_ptr = (uint8_t *)sc->ring.sring;
1395                 for (i = 0; i < sc->ring_pages; i++) {
1396                         if (sc->ring_ref[i] != GRANT_INVALID_REF) {
1397                                 gnttab_end_foreign_access_ref(sc->ring_ref[i]);
1398                                 sc->ring_ref[i] = GRANT_INVALID_REF;
1399                         }
1400                         sring_page_ptr += PAGE_SIZE;
1401                 }
1402                 free(sc->ring.sring, M_XENBLOCKFRONT);
1403                 sc->ring.sring = NULL;
1404         }
1405
1406         if (sc->shadow) {
1407
1408                 for (i = 0; i < sc->max_requests; i++) {
1409                         struct xb_command *cm;
1410
1411                         cm = &sc->shadow[i];
1412                         if (cm->sg_refs != NULL) {
1413                                 free(cm->sg_refs, M_XENBLOCKFRONT);
1414                                 cm->sg_refs = NULL;
1415                         }
1416
1417                         bus_dmamap_destroy(sc->xb_io_dmat, cm->map);
1418                 }
1419                 free(sc->shadow, M_XENBLOCKFRONT);
1420                 sc->shadow = NULL;
1421
1422                 bus_dma_tag_destroy(sc->xb_io_dmat);
1423
1424                 xb_initq_free(sc);
1425                 xb_initq_ready(sc);
1426                 xb_initq_complete(sc);
1427         }
1428
1429         if (sc->irq) {
1430                 unbind_from_irqhandler(sc->irq);
1431                 sc->irq = 0;
1432         }
1433 }
1434
1435 static int
1436 blkif_completion(struct xb_command *s)
1437 {
1438 //printf("%s: Req %p(%d)\n", __func__, s, s->nseg);
1439         gnttab_end_foreign_access_references(s->nseg, s->sg_refs);
1440         return (BLKIF_SEGS_TO_BLOCKS(s->nseg));
1441 }
1442
1443 /* ** Driver registration ** */
1444 static device_method_t blkfront_methods[] = {
1445         /* Device interface */
1446         DEVMETHOD(device_probe,         blkfront_probe),
1447         DEVMETHOD(device_attach,        blkfront_attach),
1448         DEVMETHOD(device_detach,        blkfront_detach),
1449         DEVMETHOD(device_shutdown,      bus_generic_shutdown),
1450         DEVMETHOD(device_suspend,       blkfront_suspend),
1451         DEVMETHOD(device_resume,        blkfront_resume),
1452
1453         /* Xenbus interface */
1454         DEVMETHOD(xenbus_otherend_changed, blkfront_backend_changed),
1455
1456         { 0, 0 }
1457 };
1458
1459 static driver_t blkfront_driver = {
1460         "xbd",
1461         blkfront_methods,
1462         sizeof(struct xb_softc),
1463 };
1464 devclass_t blkfront_devclass;
1465
1466 DRIVER_MODULE(xbd, xenbusb_front, blkfront_driver, blkfront_devclass, 0, 0);