drivers/scsi/xen-scsifront.c

   1 /*
   2  * Xen SCSI frontend driver
   3  *
   4  * Copyright (c) 2008, FUJITSU Limited
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License version 2
   8  * as published by the Free Software Foundation; or, when distributed
   9  * separately from the Linux kernel or incorporated into other
  10  * software packages, subject to the following license:
  11  *
  12  * Permission is hereby granted, free of charge, to any person obtaining a copy
  13  * of this source file (the "Software"), to deal in the Software without
  14  * restriction, including without limitation the rights to use, copy, modify,
  15  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  16  * and to permit persons to whom the Software is furnished to do so, subject to
  17  * 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  *
  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 DEALINGS
  28  * IN THE SOFTWARE.
  29  */
  30
  31 #include <linux/module.h>
  32 #include <linux/kernel.h>
  33 #include <linux/device.h>
  34 #include <linux/wait.h>
  35 #include <linux/interrupt.h>
  36 #include <linux/mutex.h>
  37 #include <linux/spinlock.h>
  38 #include <linux/sched.h>
  39 #include <linux/blkdev.h>
  40 #include <linux/pfn.h>
  41 #include <linux/slab.h>
  42 #include <linux/bitops.h>
  43
  44 #include <scsi/scsi_cmnd.h>
  45 #include <scsi/scsi_device.h>
  46 #include <scsi/scsi.h>
  47 #include <scsi/scsi_host.h>
  48
  49 #include <xen/xen.h>
  50 #include <xen/xenbus.h>
  51 #include <xen/grant_table.h>
  52 #include <xen/events.h>
  53 #include <xen/page.h>
  54
  55 #include <xen/interface/grant_table.h>
  56 #include <xen/interface/io/vscsiif.h>
  57 #include <xen/interface/io/protocols.h>
  58
  59 #include <asm/xen/hypervisor.h>
  60
  61
  62 #define GRANT_INVALID_REF       0
  63
  64 #define VSCSIFRONT_OP_ADD_LUN   1
  65 #define VSCSIFRONT_OP_DEL_LUN   2
  66 #define VSCSIFRONT_OP_READD_LUN 3
  67
  68 /* Tuning point. */
  69 #define VSCSIIF_DEFAULT_CMD_PER_LUN 10
  70 #define VSCSIIF_MAX_TARGET          64
  71 #define VSCSIIF_MAX_LUN             255
  72
  73 #define VSCSIIF_RING_SIZE       __CONST_RING_SIZE(vscsiif, PAGE_SIZE)
  74 #define VSCSIIF_MAX_REQS        VSCSIIF_RING_SIZE
  75
  76 #define vscsiif_grants_sg(_sg)  (PFN_UP((_sg) *         \
  77                                 sizeof(struct scsiif_request_segment)))
  78
  79 struct vscsifrnt_shadow {
  80         /* command between backend and frontend */
  81         unsigned char act;
  82         uint8_t nr_segments;
  83         uint16_t rqid;
  84         uint16_t ref_rqid;
  85
  86         unsigned int nr_grants;         /* number of grants in gref[] */
  87         struct scsiif_request_segment *sg;      /* scatter/gather elements */
  88         struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE];
  89
  90         /* Do reset or abort function. */
  91         wait_queue_head_t wq_reset;     /* reset work queue           */
  92         int wait_reset;                 /* reset work queue condition */
  93         int32_t rslt_reset;             /* reset response status:     */
  94                                         /* SUCCESS or FAILED or:      */
  95 #define RSLT_RESET_WAITING      0
  96 #define RSLT_RESET_ERR          -1
  97
  98         /* Requested struct scsi_cmnd is stored from kernel. */
  99         struct scsi_cmnd *sc;
 100         int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL];
 101 };
 102
 103 struct vscsifrnt_info {
 104         struct xenbus_device *dev;
 105
 106         struct Scsi_Host *host;
 107         int host_active;
 108
 109         unsigned int evtchn;
 110         unsigned int irq;
 111
 112         grant_ref_t ring_ref;
 113         struct vscsiif_front_ring ring;
 114         struct vscsiif_response ring_rsp;
 115
 116         spinlock_t shadow_lock;
 117         DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS);
 118         struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS];
 119
 120         /* Following items are protected by the host lock. */
 121         wait_queue_head_t wq_sync;
 122         wait_queue_head_t wq_pause;
 123         unsigned int wait_ring_available:1;
 124         unsigned int waiting_pause:1;
 125         unsigned int pause:1;
 126         unsigned callers;
 127
 128         char dev_state_path[64];
 129         struct task_struct *curr;
 130 };
 131
 132 static DEFINE_MUTEX(scsifront_mutex);
 133
 134 static void scsifront_wake_up(struct vscsifrnt_info *info)
 135 {
 136         info->wait_ring_available = 0;
 137         wake_up(&info->wq_sync);
 138 }
 139
 140 static int scsifront_get_rqid(struct vscsifrnt_info *info)
 141 {
 142         unsigned long flags;
 143         int free;
 144
 145         spin_lock_irqsave(&info->shadow_lock, flags);
 146
 147         free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
 148         __clear_bit(free, info->shadow_free_bitmap);
 149
 150         spin_unlock_irqrestore(&info->shadow_lock, flags);
 151
 152         return free;
 153 }
 154
 155 static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
 156 {
 157         int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
 158
 159         __set_bit(id, info->shadow_free_bitmap);
 160         info->shadow[id] = NULL;
 161
 162         return empty || info->wait_ring_available;
 163 }
 164
 165 static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
 166 {
 167         unsigned long flags;
 168         int kick;
 169
 170         spin_lock_irqsave(&info->shadow_lock, flags);
 171         kick = _scsifront_put_rqid(info, id);
 172         spin_unlock_irqrestore(&info->shadow_lock, flags);
 173
 174         if (kick)
 175                 scsifront_wake_up(info);
 176 }
 177
 178 static int scsifront_do_request(struct vscsifrnt_info *info,
 179                                 struct vscsifrnt_shadow *shadow)
 180 {
 181         struct vscsiif_front_ring *ring = &(info->ring);
 182         struct vscsiif_request *ring_req;
 183         struct scsi_cmnd *sc = shadow->sc;
 184         uint32_t id;
 185         int i, notify;
 186
 187         if (RING_FULL(&info->ring))
 188                 return -EBUSY;
 189
 190         id = scsifront_get_rqid(info);  /* use id in response */
 191         if (id >= VSCSIIF_MAX_REQS)
 192                 return -EBUSY;
 193
 194         info->shadow[id] = shadow;
 195         shadow->rqid = id;
 196
 197         ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt);
 198         ring->req_prod_pvt++;
 199
 200         ring_req->rqid        = id;
 201         ring_req->act         = shadow->act;
 202         ring_req->ref_rqid    = shadow->ref_rqid;
 203         ring_req->nr_segments = shadow->nr_segments;
 204
 205         ring_req->id      = sc->device->id;
 206         ring_req->lun     = sc->device->lun;
 207         ring_req->channel = sc->device->channel;
 208         ring_req->cmd_len = sc->cmd_len;
 209
 210         BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE);
 211
 212         memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len);
 213
 214         ring_req->sc_data_direction   = (uint8_t)sc->sc_data_direction;
 215         ring_req->timeout_per_command = scsi_cmd_to_rq(sc)->timeout / HZ;
 216
 217         for (i = 0; i < (shadow->nr_segments & ~VSCSIIF_SG_GRANT); i++)
 218                 ring_req->seg[i] = shadow->seg[i];
 219
 220         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify);
 221         if (notify)
 222                 notify_remote_via_irq(info->irq);
 223
 224         return 0;
 225 }
 226
 227 static void scsifront_gnttab_done(struct vscsifrnt_info *info,
 228                                   struct vscsifrnt_shadow *shadow)
 229 {
 230         int i;
 231
 232         if (shadow->sc->sc_data_direction == DMA_NONE)
 233                 return;
 234
 235         for (i = 0; i < shadow->nr_grants; i++) {
 236                 if (unlikely(!gnttab_try_end_foreign_access(shadow->gref[i]))) {
 237                         shost_printk(KERN_ALERT, info->host, KBUILD_MODNAME
 238                                      "grant still in use by backend\n");
 239                         BUG();
 240                 }
 241         }
 242
 243         kfree(shadow->sg);
 244 }
 245
 246 static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info,
 247                                    struct vscsiif_response *ring_rsp)
 248 {
 249         struct vscsifrnt_shadow *shadow;
 250         struct scsi_cmnd *sc;
 251         uint32_t id;
 252         uint8_t sense_len;
 253         int result;
 254
 255         id = ring_rsp->rqid;
 256         shadow = info->shadow[id];
 257         sc = shadow->sc;
 258
 259         BUG_ON(sc == NULL);
 260
 261         scsifront_gnttab_done(info, shadow);
 262         scsifront_put_rqid(info, id);
 263
 264         result = ring_rsp->rslt;
 265         if (result >> 24)
 266                 set_host_byte(sc, DID_ERROR);
 267         else
 268                 set_host_byte(sc, host_byte(result));
 269         set_status_byte(sc, result & 0xff);
 270         scsi_set_resid(sc, ring_rsp->residual_len);
 271
 272         sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE,
 273                           ring_rsp->sense_len);
 274
 275         if (sense_len)
 276                 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len);
 277
 278         sc->scsi_done(sc);
 279 }
 280
 281 static void scsifront_sync_cmd_done(struct vscsifrnt_info *info,
 282                                     struct vscsiif_response *ring_rsp)
 283 {
 284         uint16_t id = ring_rsp->rqid;
 285         unsigned long flags;
 286         struct vscsifrnt_shadow *shadow = info->shadow[id];
 287         int kick;
 288
 289         spin_lock_irqsave(&info->shadow_lock, flags);
 290         shadow->wait_reset = 1;
 291         switch (shadow->rslt_reset) {
 292         case RSLT_RESET_WAITING:
 293                 shadow->rslt_reset = ring_rsp->rslt;
 294                 break;
 295         case RSLT_RESET_ERR:
 296                 kick = _scsifront_put_rqid(info, id);
 297                 spin_unlock_irqrestore(&info->shadow_lock, flags);
 298                 kfree(shadow);
 299                 if (kick)
 300                         scsifront_wake_up(info);
 301                 return;
 302         default:
 303                 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
 304                              "bad reset state %d, possibly leaking %u\n",
 305                              shadow->rslt_reset, id);
 306                 break;
 307         }
 308         spin_unlock_irqrestore(&info->shadow_lock, flags);
 309
 310         wake_up(&shadow->wq_reset);
 311 }
 312
 313 static void scsifront_do_response(struct vscsifrnt_info *info,
 314                                   struct vscsiif_response *ring_rsp)
 315 {
 316         if (WARN(ring_rsp->rqid >= VSCSIIF_MAX_REQS ||
 317                  test_bit(ring_rsp->rqid, info->shadow_free_bitmap),
 318                  "illegal rqid %u returned by backend!\n", ring_rsp->rqid))
 319                 return;
 320
 321         if (info->shadow[ring_rsp->rqid]->act == VSCSIIF_ACT_SCSI_CDB)
 322                 scsifront_cdb_cmd_done(info, ring_rsp);
 323         else
 324                 scsifront_sync_cmd_done(info, ring_rsp);
 325 }
 326
 327 static int scsifront_ring_drain(struct vscsifrnt_info *info)
 328 {
 329         struct vscsiif_response *ring_rsp;
 330         RING_IDX i, rp;
 331         int more_to_do = 0;
 332
 333         rp = info->ring.sring->rsp_prod;
 334         rmb();  /* ordering required respective to dom0 */
 335         for (i = info->ring.rsp_cons; i != rp; i++) {
 336                 ring_rsp = RING_GET_RESPONSE(&info->ring, i);
 337                 scsifront_do_response(info, ring_rsp);
 338         }
 339
 340         info->ring.rsp_cons = i;
 341
 342         if (i != info->ring.req_prod_pvt)
 343                 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
 344         else
 345                 info->ring.sring->rsp_event = i + 1;
 346
 347         return more_to_do;
 348 }
 349
 350 static int scsifront_cmd_done(struct vscsifrnt_info *info)
 351 {
 352         int more_to_do;
 353         unsigned long flags;
 354
 355         spin_lock_irqsave(info->host->host_lock, flags);
 356
 357         more_to_do = scsifront_ring_drain(info);
 358
 359         info->wait_ring_available = 0;
 360
 361         spin_unlock_irqrestore(info->host->host_lock, flags);
 362
 363         wake_up(&info->wq_sync);
 364
 365         return more_to_do;
 366 }
 367
 368 static irqreturn_t scsifront_irq_fn(int irq, void *dev_id)
 369 {
 370         struct vscsifrnt_info *info = dev_id;
 371
 372         while (scsifront_cmd_done(info))
 373                 /* Yield point for this unbounded loop. */
 374                 cond_resched();
 375
 376         return IRQ_HANDLED;
 377 }
 378
 379 static void scsifront_finish_all(struct vscsifrnt_info *info)
 380 {
 381         unsigned i;
 382         struct vscsiif_response resp;
 383
 384         scsifront_ring_drain(info);
 385
 386         for (i = 0; i < VSCSIIF_MAX_REQS; i++) {
 387                 if (test_bit(i, info->shadow_free_bitmap))
 388                         continue;
 389                 resp.rqid = i;
 390                 resp.sense_len = 0;
 391                 resp.rslt = DID_RESET << 16;
 392                 resp.residual_len = 0;
 393                 scsifront_do_response(info, &resp);
 394         }
 395 }
 396
 397 static int map_data_for_request(struct vscsifrnt_info *info,
 398                                 struct scsi_cmnd *sc,
 399                                 struct vscsifrnt_shadow *shadow)
 400 {
 401         grant_ref_t gref_head;
 402         struct page *page;
 403         int err, ref, ref_cnt = 0;
 404         int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE);
 405         unsigned int i, off, len, bytes;
 406         unsigned int data_len = scsi_bufflen(sc);
 407         unsigned int data_grants = 0, seg_grants = 0;
 408         struct scatterlist *sg;
 409         struct scsiif_request_segment *seg;
 410
 411         if (sc->sc_data_direction == DMA_NONE || !data_len)
 412                 return 0;
 413
 414         scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)
 415                 data_grants += PFN_UP(sg->offset + sg->length);
 416
 417         if (data_grants > VSCSIIF_SG_TABLESIZE) {
 418                 if (data_grants > info->host->sg_tablesize) {
 419                         shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
 420                              "Unable to map request_buffer for command!\n");
 421                         return -E2BIG;
 422                 }
 423                 seg_grants = vscsiif_grants_sg(data_grants);
 424                 shadow->sg = kcalloc(data_grants,
 425                         sizeof(struct scsiif_request_segment), GFP_ATOMIC);
 426                 if (!shadow->sg)
 427                         return -ENOMEM;
 428         }
 429         seg = shadow->sg ? : shadow->seg;
 430
 431         err = gnttab_alloc_grant_references(seg_grants + data_grants,
 432                                             &gref_head);
 433         if (err) {
 434                 kfree(shadow->sg);
 435                 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
 436                              "gnttab_alloc_grant_references() error\n");
 437                 return -ENOMEM;
 438         }
 439
 440         if (seg_grants) {
 441                 page = virt_to_page(seg);
 442                 off = offset_in_page(seg);
 443                 len = sizeof(struct scsiif_request_segment) * data_grants;
 444                 while (len > 0) {
 445                         bytes = min_t(unsigned int, len, PAGE_SIZE - off);
 446
 447                         ref = gnttab_claim_grant_reference(&gref_head);
 448                         BUG_ON(ref == -ENOSPC);
 449
 450                         gnttab_grant_foreign_access_ref(ref,
 451                                 info->dev->otherend_id,
 452                                 xen_page_to_gfn(page), 1);
 453                         shadow->gref[ref_cnt] = ref;
 454                         shadow->seg[ref_cnt].gref   = ref;
 455                         shadow->seg[ref_cnt].offset = (uint16_t)off;
 456                         shadow->seg[ref_cnt].length = (uint16_t)bytes;
 457
 458                         page++;
 459                         len -= bytes;
 460                         off = 0;
 461                         ref_cnt++;
 462                 }
 463                 BUG_ON(seg_grants < ref_cnt);
 464                 seg_grants = ref_cnt;
 465         }
 466
 467         scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {
 468                 page = sg_page(sg);
 469                 off = sg->offset;
 470                 len = sg->length;
 471
 472                 while (len > 0 && data_len > 0) {
 473                         /*
 474                          * sg sends a scatterlist that is larger than
 475                          * the data_len it wants transferred for certain
 476                          * IO sizes.
 477                          */
 478                         bytes = min_t(unsigned int, len, PAGE_SIZE - off);
 479                         bytes = min(bytes, data_len);
 480
 481                         ref = gnttab_claim_grant_reference(&gref_head);
 482                         BUG_ON(ref == -ENOSPC);
 483
 484                         gnttab_grant_foreign_access_ref(ref,
 485                                 info->dev->otherend_id,
 486                                 xen_page_to_gfn(page),
 487                                 grant_ro);
 488
 489                         shadow->gref[ref_cnt] = ref;
 490                         seg->gref   = ref;
 491                         seg->offset = (uint16_t)off;
 492                         seg->length = (uint16_t)bytes;
 493
 494                         page++;
 495                         seg++;
 496                         len -= bytes;
 497                         data_len -= bytes;
 498                         off = 0;
 499                         ref_cnt++;
 500                 }
 501         }
 502
 503         if (seg_grants)
 504                 shadow->nr_segments = VSCSIIF_SG_GRANT | seg_grants;
 505         else
 506                 shadow->nr_segments = (uint8_t)ref_cnt;
 507         shadow->nr_grants = ref_cnt;
 508
 509         return 0;
 510 }
 511
 512 static int scsifront_enter(struct vscsifrnt_info *info)
 513 {
 514         if (info->pause)
 515                 return 1;
 516         info->callers++;
 517         return 0;
 518 }
 519
 520 static void scsifront_return(struct vscsifrnt_info *info)
 521 {
 522         info->callers--;
 523         if (info->callers)
 524                 return;
 525
 526         if (!info->waiting_pause)
 527                 return;
 528
 529         info->waiting_pause = 0;
 530         wake_up(&info->wq_pause);
 531 }
 532
 533 static int scsifront_queuecommand(struct Scsi_Host *shost,
 534                                   struct scsi_cmnd *sc)
 535 {
 536         struct vscsifrnt_info *info = shost_priv(shost);
 537         struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc);
 538         unsigned long flags;
 539         int err;
 540
 541         sc->result = 0;
 542
 543         shadow->sc  = sc;
 544         shadow->act = VSCSIIF_ACT_SCSI_CDB;
 545
 546         spin_lock_irqsave(shost->host_lock, flags);
 547         if (scsifront_enter(info)) {
 548                 spin_unlock_irqrestore(shost->host_lock, flags);
 549                 return SCSI_MLQUEUE_HOST_BUSY;
 550         }
 551
 552         err = map_data_for_request(info, sc, shadow);
 553         if (err < 0) {
 554                 pr_debug("%s: err %d\n", __func__, err);
 555                 scsifront_return(info);
 556                 spin_unlock_irqrestore(shost->host_lock, flags);
 557                 if (err == -ENOMEM)
 558                         return SCSI_MLQUEUE_HOST_BUSY;
 559                 sc->result = DID_ERROR << 16;
 560                 sc->scsi_done(sc);
 561                 return 0;
 562         }
 563
 564         if (scsifront_do_request(info, shadow)) {
 565                 scsifront_gnttab_done(info, shadow);
 566                 goto busy;
 567         }
 568
 569         scsifront_return(info);
 570         spin_unlock_irqrestore(shost->host_lock, flags);
 571
 572         return 0;
 573
 574 busy:
 575         scsifront_return(info);
 576         spin_unlock_irqrestore(shost->host_lock, flags);
 577         pr_debug("%s: busy\n", __func__);
 578         return SCSI_MLQUEUE_HOST_BUSY;
 579 }
 580
 581 /*
 582  * Any exception handling (reset or abort) must be forwarded to the backend.
 583  * We have to wait until an answer is returned. This answer contains the
 584  * result to be returned to the requestor.
 585  */
 586 static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)
 587 {
 588         struct Scsi_Host *host = sc->device->host;
 589         struct vscsifrnt_info *info = shost_priv(host);
 590         struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
 591         int err = 0;
 592
 593         shadow = kzalloc(sizeof(*shadow), GFP_NOIO);
 594         if (!shadow)
 595                 return FAILED;
 596
 597         shadow->act = act;
 598         shadow->rslt_reset = RSLT_RESET_WAITING;
 599         shadow->sc = sc;
 600         shadow->ref_rqid = s->rqid;
 601         init_waitqueue_head(&shadow->wq_reset);
 602
 603         spin_lock_irq(host->host_lock);
 604
 605         for (;;) {
 606                 if (scsifront_enter(info))
 607                         goto fail;
 608
 609                 if (!scsifront_do_request(info, shadow))
 610                         break;
 611
 612                 scsifront_return(info);
 613                 if (err)
 614                         goto fail;
 615                 info->wait_ring_available = 1;
 616                 spin_unlock_irq(host->host_lock);
 617                 err = wait_event_interruptible(info->wq_sync,
 618                                                !info->wait_ring_available);
 619                 spin_lock_irq(host->host_lock);
 620         }
 621
 622         spin_unlock_irq(host->host_lock);
 623         err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
 624         spin_lock_irq(host->host_lock);
 625
 626         if (!err) {
 627                 err = shadow->rslt_reset;
 628                 scsifront_put_rqid(info, shadow->rqid);
 629                 kfree(shadow);
 630         } else {
 631                 spin_lock(&info->shadow_lock);
 632                 shadow->rslt_reset = RSLT_RESET_ERR;
 633                 spin_unlock(&info->shadow_lock);
 634                 err = FAILED;
 635         }
 636
 637         scsifront_return(info);
 638         spin_unlock_irq(host->host_lock);
 639         return err;
 640
 641 fail:
 642         spin_unlock_irq(host->host_lock);
 643         kfree(shadow);
 644         return FAILED;
 645 }
 646
 647 static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
 648 {
 649         pr_debug("%s\n", __func__);
 650         return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);
 651 }
 652
 653 static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
 654 {
 655         pr_debug("%s\n", __func__);
 656         return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);
 657 }
 658
 659 static int scsifront_sdev_configure(struct scsi_device *sdev)
 660 {
 661         struct vscsifrnt_info *info = shost_priv(sdev->host);
 662         int err;
 663
 664         if (info && current == info->curr) {
 665                 err = xenbus_printf(XBT_NIL, info->dev->nodename,
 666                               info->dev_state_path, "%d", XenbusStateConnected);
 667                 if (err) {
 668                         xenbus_dev_error(info->dev, err,
 669                                 "%s: writing dev_state_path", __func__);
 670                         return err;
 671                 }
 672         }
 673
 674         return 0;
 675 }
 676
 677 static void scsifront_sdev_destroy(struct scsi_device *sdev)
 678 {
 679         struct vscsifrnt_info *info = shost_priv(sdev->host);
 680         int err;
 681
 682         if (info && current == info->curr) {
 683                 err = xenbus_printf(XBT_NIL, info->dev->nodename,
 684                               info->dev_state_path, "%d", XenbusStateClosed);
 685                 if (err)
 686                         xenbus_dev_error(info->dev, err,
 687                                 "%s: writing dev_state_path", __func__);
 688         }
 689 }
 690
 691 static struct scsi_host_template scsifront_sht = {
 692         .module                 = THIS_MODULE,
 693         .name                   = "Xen SCSI frontend driver",
 694         .queuecommand           = scsifront_queuecommand,
 695         .eh_abort_handler       = scsifront_eh_abort_handler,
 696         .eh_device_reset_handler = scsifront_dev_reset_handler,
 697         .slave_configure        = scsifront_sdev_configure,
 698         .slave_destroy          = scsifront_sdev_destroy,
 699         .cmd_per_lun            = VSCSIIF_DEFAULT_CMD_PER_LUN,
 700         .can_queue              = VSCSIIF_MAX_REQS,
 701         .this_id                = -1,
 702         .cmd_size               = sizeof(struct vscsifrnt_shadow),
 703         .sg_tablesize           = VSCSIIF_SG_TABLESIZE,
 704         .proc_name              = "scsifront",
 705 };
 706
 707 static int scsifront_alloc_ring(struct vscsifrnt_info *info)
 708 {
 709         struct xenbus_device *dev = info->dev;
 710         struct vscsiif_sring *sring;
 711         grant_ref_t gref;
 712         int err = -ENOMEM;
 713
 714         /***** Frontend to Backend ring start *****/
 715         sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL);
 716         if (!sring) {
 717                 xenbus_dev_fatal(dev, err,
 718                         "fail to allocate shared ring (Front to Back)");
 719                 return err;
 720         }
 721         SHARED_RING_INIT(sring);
 722         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 723
 724         err = xenbus_grant_ring(dev, sring, 1, &gref);
 725         if (err < 0) {
 726                 free_page((unsigned long)sring);
 727                 xenbus_dev_fatal(dev, err,
 728                         "fail to grant shared ring (Front to Back)");
 729                 return err;
 730         }
 731         info->ring_ref = gref;
 732
 733         err = xenbus_alloc_evtchn(dev, &info->evtchn);
 734         if (err) {
 735                 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
 736                 goto free_gnttab;
 737         }
 738
 739         err = bind_evtchn_to_irq(info->evtchn);
 740         if (err <= 0) {
 741                 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
 742                 goto free_gnttab;
 743         }
 744
 745         info->irq = err;
 746
 747         err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
 748                                    IRQF_ONESHOT, "scsifront", info);
 749         if (err) {
 750                 xenbus_dev_fatal(dev, err, "request_threaded_irq");
 751                 goto free_irq;
 752         }
 753
 754         return 0;
 755
 756 /* free resource */
 757 free_irq:
 758         unbind_from_irqhandler(info->irq, info);
 759 free_gnttab:
 760         gnttab_end_foreign_access(info->ring_ref, 0,
 761                                   (unsigned long)info->ring.sring);
 762
 763         return err;
 764 }
 765
 766 static void scsifront_free_ring(struct vscsifrnt_info *info)
 767 {
 768         unbind_from_irqhandler(info->irq, info);
 769         gnttab_end_foreign_access(info->ring_ref, 0,
 770                                   (unsigned long)info->ring.sring);
 771 }
 772
 773 static int scsifront_init_ring(struct vscsifrnt_info *info)
 774 {
 775         struct xenbus_device *dev = info->dev;
 776         struct xenbus_transaction xbt;
 777         int err;
 778
 779         pr_debug("%s\n", __func__);
 780
 781         err = scsifront_alloc_ring(info);
 782         if (err)
 783                 return err;
 784         pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
 785
 786 again:
 787         err = xenbus_transaction_start(&xbt);
 788         if (err)
 789                 xenbus_dev_fatal(dev, err, "starting transaction");
 790
 791         err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
 792                             info->ring_ref);
 793         if (err) {
 794                 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
 795                 goto fail;
 796         }
 797
 798         err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
 799                             info->evtchn);
 800
 801         if (err) {
 802                 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
 803                 goto fail;
 804         }
 805
 806         err = xenbus_transaction_end(xbt, 0);
 807         if (err) {
 808                 if (err == -EAGAIN)
 809                         goto again;
 810                 xenbus_dev_fatal(dev, err, "completing transaction");
 811                 goto free_sring;
 812         }
 813
 814         return 0;
 815
 816 fail:
 817         xenbus_transaction_end(xbt, 1);
 818 free_sring:
 819         scsifront_free_ring(info);
 820
 821         return err;
 822 }
 823
 824
 825 static int scsifront_probe(struct xenbus_device *dev,
 826                            const struct xenbus_device_id *id)
 827 {
 828         struct vscsifrnt_info *info;
 829         struct Scsi_Host *host;
 830         int err = -ENOMEM;
 831         char name[TASK_COMM_LEN];
 832
 833         host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
 834         if (!host) {
 835                 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
 836                 return err;
 837         }
 838         info = (struct vscsifrnt_info *)host->hostdata;
 839
 840         dev_set_drvdata(&dev->dev, info);
 841         info->dev = dev;
 842
 843         bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
 844
 845         err = scsifront_init_ring(info);
 846         if (err) {
 847                 scsi_host_put(host);
 848                 return err;
 849         }
 850
 851         init_waitqueue_head(&info->wq_sync);
 852         init_waitqueue_head(&info->wq_pause);
 853         spin_lock_init(&info->shadow_lock);
 854
 855         snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
 856
 857         host->max_id      = VSCSIIF_MAX_TARGET;
 858         host->max_channel = 0;
 859         host->max_lun     = VSCSIIF_MAX_LUN;
 860         host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
 861         host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
 862
 863         err = scsi_add_host(host, &dev->dev);
 864         if (err) {
 865                 dev_err(&dev->dev, "fail to add scsi host %d\n", err);
 866                 goto free_sring;
 867         }
 868         info->host = host;
 869         info->host_active = 1;
 870
 871         xenbus_switch_state(dev, XenbusStateInitialised);
 872
 873         return 0;
 874
 875 free_sring:
 876         scsifront_free_ring(info);
 877         scsi_host_put(host);
 878         return err;
 879 }
 880
 881 static int scsifront_resume(struct xenbus_device *dev)
 882 {
 883         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 884         struct Scsi_Host *host = info->host;
 885         int err;
 886
 887         spin_lock_irq(host->host_lock);
 888
 889         /* Finish all still pending commands. */
 890         scsifront_finish_all(info);
 891
 892         spin_unlock_irq(host->host_lock);
 893
 894         /* Reconnect to dom0. */
 895         scsifront_free_ring(info);
 896         err = scsifront_init_ring(info);
 897         if (err) {
 898                 dev_err(&dev->dev, "fail to resume %d\n", err);
 899                 scsi_host_put(host);
 900                 return err;
 901         }
 902
 903         xenbus_switch_state(dev, XenbusStateInitialised);
 904
 905         return 0;
 906 }
 907
 908 static int scsifront_suspend(struct xenbus_device *dev)
 909 {
 910         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 911         struct Scsi_Host *host = info->host;
 912         int err = 0;
 913
 914         /* No new commands for the backend. */
 915         spin_lock_irq(host->host_lock);
 916         info->pause = 1;
 917         while (info->callers && !err) {
 918                 info->waiting_pause = 1;
 919                 info->wait_ring_available = 0;
 920                 spin_unlock_irq(host->host_lock);
 921                 wake_up(&info->wq_sync);
 922                 err = wait_event_interruptible(info->wq_pause,
 923                                                !info->waiting_pause);
 924                 spin_lock_irq(host->host_lock);
 925         }
 926         spin_unlock_irq(host->host_lock);
 927         return err;
 928 }
 929
 930 static int scsifront_remove(struct xenbus_device *dev)
 931 {
 932         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 933
 934         pr_debug("%s: %s removed\n", __func__, dev->nodename);
 935
 936         mutex_lock(&scsifront_mutex);
 937         if (info->host_active) {
 938                 /* Scsi_host not yet removed */
 939                 scsi_remove_host(info->host);
 940                 info->host_active = 0;
 941         }
 942         mutex_unlock(&scsifront_mutex);
 943
 944         scsifront_free_ring(info);
 945         scsi_host_put(info->host);
 946
 947         return 0;
 948 }
 949
 950 static void scsifront_disconnect(struct vscsifrnt_info *info)
 951 {
 952         struct xenbus_device *dev = info->dev;
 953         struct Scsi_Host *host = info->host;
 954
 955         pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
 956
 957         /*
 958          * When this function is executed, all devices of
 959          * Frontend have been deleted.
 960          * Therefore, it need not block I/O before remove_host.
 961          */
 962
 963         mutex_lock(&scsifront_mutex);
 964         if (info->host_active) {
 965                 scsi_remove_host(host);
 966                 info->host_active = 0;
 967         }
 968         mutex_unlock(&scsifront_mutex);
 969
 970         xenbus_frontend_closed(dev);
 971 }
 972
 973 static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
 974 {
 975         struct xenbus_device *dev = info->dev;
 976         int i, err = 0;
 977         char str[64];
 978         char **dir;
 979         unsigned int dir_n = 0;
 980         unsigned int device_state;
 981         unsigned int hst, chn, tgt, lun;
 982         struct scsi_device *sdev;
 983
 984         dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
 985         if (IS_ERR(dir))
 986                 return;
 987
 988         /* mark current task as the one allowed to modify device states */
 989         BUG_ON(info->curr);
 990         info->curr = current;
 991
 992         for (i = 0; i < dir_n; i++) {
 993                 /* read status */
 994                 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
 995                 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
 996                                    &device_state);
 997                 if (XENBUS_EXIST_ERR(err))
 998                         continue;
 999
1000                 /* virtual SCSI device */
1001                 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
1002                 err = xenbus_scanf(XBT_NIL, dev->otherend, str,
1003                                    "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
1004                 if (XENBUS_EXIST_ERR(err))
1005                         continue;
1006
1007                 /*
1008                  * Front device state path, used in slave_configure called
1009                  * on successfull scsi_add_device, and in slave_destroy called
1010                  * on remove of a device.
1011                  */
1012                 snprintf(info->dev_state_path, sizeof(info->dev_state_path),
1013                          "vscsi-devs/%s/state", dir[i]);
1014
1015                 switch (op) {
1016                 case VSCSIFRONT_OP_ADD_LUN:
1017                         if (device_state != XenbusStateInitialised)
1018                                 break;
1019
1020                         if (scsi_add_device(info->host, chn, tgt, lun)) {
1021                                 dev_err(&dev->dev, "scsi_add_device\n");
1022                                 err = xenbus_printf(XBT_NIL, dev->nodename,
1023                                               info->dev_state_path,
1024                                               "%d", XenbusStateClosed);
1025                                 if (err)
1026                                         xenbus_dev_error(dev, err,
1027                                                 "%s: writing dev_state_path", __func__);
1028                         }
1029                         break;
1030                 case VSCSIFRONT_OP_DEL_LUN:
1031                         if (device_state != XenbusStateClosing)
1032                                 break;
1033
1034                         sdev = scsi_device_lookup(info->host, chn, tgt, lun);
1035                         if (sdev) {
1036                                 scsi_remove_device(sdev);
1037                                 scsi_device_put(sdev);
1038                         }
1039                         break;
1040                 case VSCSIFRONT_OP_READD_LUN:
1041                         if (device_state == XenbusStateConnected) {
1042                                 err = xenbus_printf(XBT_NIL, dev->nodename,
1043                                               info->dev_state_path,
1044                                               "%d", XenbusStateConnected);
1045                                 if (err)
1046                                         xenbus_dev_error(dev, err,
1047                                                 "%s: writing dev_state_path", __func__);
1048                         }
1049                         break;
1050                 default:
1051                         break;
1052                 }
1053         }
1054
1055         info->curr = NULL;
1056
1057         kfree(dir);
1058 }
1059
1060 static void scsifront_read_backend_params(struct xenbus_device *dev,
1061                                           struct vscsifrnt_info *info)
1062 {
1063         unsigned int sg_grant, nr_segs;
1064         struct Scsi_Host *host = info->host;
1065
1066         sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0);
1067         nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
1068         nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
1069         nr_segs = min_t(unsigned int, nr_segs,
1070                         VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
1071                         sizeof(struct scsiif_request_segment));
1072
1073         if (!info->pause && sg_grant)
1074                 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);
1075         else if (info->pause && nr_segs < host->sg_tablesize)
1076                 dev_warn(&dev->dev,
1077                          "SG entries decreased from %d to %u - device may not work properly anymore\n",
1078                          host->sg_tablesize, nr_segs);
1079
1080         host->sg_tablesize = nr_segs;
1081         host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;
1082 }
1083
1084 static void scsifront_backend_changed(struct xenbus_device *dev,
1085                                       enum xenbus_state backend_state)
1086 {
1087         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1088
1089         pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
1090
1091         switch (backend_state) {
1092         case XenbusStateUnknown:
1093         case XenbusStateInitialising:
1094         case XenbusStateInitWait:
1095         case XenbusStateInitialised:
1096                 break;
1097
1098         case XenbusStateConnected:
1099                 scsifront_read_backend_params(dev, info);
1100
1101                 if (info->pause) {
1102                         scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);
1103                         xenbus_switch_state(dev, XenbusStateConnected);
1104                         info->pause = 0;
1105                         return;
1106                 }
1107
1108                 if (xenbus_read_driver_state(dev->nodename) ==
1109                     XenbusStateInitialised)
1110                         scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1111
1112                 if (dev->state != XenbusStateConnected)
1113                         xenbus_switch_state(dev, XenbusStateConnected);
1114                 break;
1115
1116         case XenbusStateClosed:
1117                 if (dev->state == XenbusStateClosed)
1118                         break;
1119                 fallthrough;    /* Missed the backend's Closing state */
1120         case XenbusStateClosing:
1121                 scsifront_disconnect(info);
1122                 break;
1123
1124         case XenbusStateReconfiguring:
1125                 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
1126                 xenbus_switch_state(dev, XenbusStateReconfiguring);
1127                 break;
1128
1129         case XenbusStateReconfigured:
1130                 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1131                 xenbus_switch_state(dev, XenbusStateConnected);
1132                 break;
1133         }
1134 }
1135
1136 static const struct xenbus_device_id scsifront_ids[] = {
1137         { "vscsi" },
1138         { "" }
1139 };
1140
1141 static struct xenbus_driver scsifront_driver = {
1142         .ids                    = scsifront_ids,
1143         .probe                  = scsifront_probe,
1144         .remove                 = scsifront_remove,
1145         .resume                 = scsifront_resume,
1146         .suspend                = scsifront_suspend,
1147         .otherend_changed       = scsifront_backend_changed,
1148 };
1149
1150 static int __init scsifront_init(void)
1151 {
1152         if (!xen_domain())
1153                 return -ENODEV;
1154
1155         return xenbus_register_frontend(&scsifront_driver);
1156 }
1157 module_init(scsifront_init);
1158
1159 static void __exit scsifront_exit(void)
1160 {
1161         xenbus_unregister_driver(&scsifront_driver);
1162 }
1163 module_exit(scsifront_exit);
1164
1165 MODULE_DESCRIPTION("Xen SCSI frontend driver");
1166 MODULE_LICENSE("GPL");
1167 MODULE_ALIAS("xen:vscsi");
1168 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");