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 = sc->request->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
 254         id = ring_rsp->rqid;
 255         shadow = info->shadow[id];
 256         sc = shadow->sc;
 257
 258         BUG_ON(sc == NULL);
 259
 260         scsifront_gnttab_done(info, shadow);
 261         scsifront_put_rqid(info, id);
 262
 263         sc->result = ring_rsp->rslt;
 264         scsi_set_resid(sc, ring_rsp->residual_len);
 265
 266         sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE,
 267                           ring_rsp->sense_len);
 268
 269         if (sense_len)
 270                 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len);
 271
 272         sc->scsi_done(sc);
 273 }
 274
 275 static void scsifront_sync_cmd_done(struct vscsifrnt_info *info,
 276                                     struct vscsiif_response *ring_rsp)
 277 {
 278         uint16_t id = ring_rsp->rqid;
 279         unsigned long flags;
 280         struct vscsifrnt_shadow *shadow = info->shadow[id];
 281         int kick;
 282
 283         spin_lock_irqsave(&info->shadow_lock, flags);
 284         shadow->wait_reset = 1;
 285         switch (shadow->rslt_reset) {
 286         case RSLT_RESET_WAITING:
 287                 shadow->rslt_reset = ring_rsp->rslt;
 288                 break;
 289         case RSLT_RESET_ERR:
 290                 kick = _scsifront_put_rqid(info, id);
 291                 spin_unlock_irqrestore(&info->shadow_lock, flags);
 292                 kfree(shadow);
 293                 if (kick)
 294                         scsifront_wake_up(info);
 295                 return;
 296         default:
 297                 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
 298                              "bad reset state %d, possibly leaking %u\n",
 299                              shadow->rslt_reset, id);
 300                 break;
 301         }
 302         spin_unlock_irqrestore(&info->shadow_lock, flags);
 303
 304         wake_up(&shadow->wq_reset);
 305 }
 306
 307 static void scsifront_do_response(struct vscsifrnt_info *info,
 308                                   struct vscsiif_response *ring_rsp)
 309 {
 310         if (WARN(ring_rsp->rqid >= VSCSIIF_MAX_REQS ||
 311                  test_bit(ring_rsp->rqid, info->shadow_free_bitmap),
 312                  "illegal rqid %u returned by backend!\n", ring_rsp->rqid))
 313                 return;
 314
 315         if (info->shadow[ring_rsp->rqid]->act == VSCSIIF_ACT_SCSI_CDB)
 316                 scsifront_cdb_cmd_done(info, ring_rsp);
 317         else
 318                 scsifront_sync_cmd_done(info, ring_rsp);
 319 }
 320
 321 static int scsifront_ring_drain(struct vscsifrnt_info *info)
 322 {
 323         struct vscsiif_response *ring_rsp;
 324         RING_IDX i, rp;
 325         int more_to_do = 0;
 326
 327         rp = info->ring.sring->rsp_prod;
 328         rmb();  /* ordering required respective to dom0 */
 329         for (i = info->ring.rsp_cons; i != rp; i++) {
 330                 ring_rsp = RING_GET_RESPONSE(&info->ring, i);
 331                 scsifront_do_response(info, ring_rsp);
 332         }
 333
 334         info->ring.rsp_cons = i;
 335
 336         if (i != info->ring.req_prod_pvt)
 337                 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
 338         else
 339                 info->ring.sring->rsp_event = i + 1;
 340
 341         return more_to_do;
 342 }
 343
 344 static int scsifront_cmd_done(struct vscsifrnt_info *info)
 345 {
 346         int more_to_do;
 347         unsigned long flags;
 348
 349         spin_lock_irqsave(info->host->host_lock, flags);
 350
 351         more_to_do = scsifront_ring_drain(info);
 352
 353         info->wait_ring_available = 0;
 354
 355         spin_unlock_irqrestore(info->host->host_lock, flags);
 356
 357         wake_up(&info->wq_sync);
 358
 359         return more_to_do;
 360 }
 361
 362 static irqreturn_t scsifront_irq_fn(int irq, void *dev_id)
 363 {
 364         struct vscsifrnt_info *info = dev_id;
 365
 366         while (scsifront_cmd_done(info))
 367                 /* Yield point for this unbounded loop. */
 368                 cond_resched();
 369
 370         return IRQ_HANDLED;
 371 }
 372
 373 static void scsifront_finish_all(struct vscsifrnt_info *info)
 374 {
 375         unsigned i;
 376         struct vscsiif_response resp;
 377
 378         scsifront_ring_drain(info);
 379
 380         for (i = 0; i < VSCSIIF_MAX_REQS; i++) {
 381                 if (test_bit(i, info->shadow_free_bitmap))
 382                         continue;
 383                 resp.rqid = i;
 384                 resp.sense_len = 0;
 385                 resp.rslt = DID_RESET << 16;
 386                 resp.residual_len = 0;
 387                 scsifront_do_response(info, &resp);
 388         }
 389 }
 390
 391 static int map_data_for_request(struct vscsifrnt_info *info,
 392                                 struct scsi_cmnd *sc,
 393                                 struct vscsifrnt_shadow *shadow)
 394 {
 395         grant_ref_t gref_head;
 396         struct page *page;
 397         int err, ref, ref_cnt = 0;
 398         int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE);
 399         unsigned int i, off, len, bytes;
 400         unsigned int data_len = scsi_bufflen(sc);
 401         unsigned int data_grants = 0, seg_grants = 0;
 402         struct scatterlist *sg;
 403         struct scsiif_request_segment *seg;
 404
 405         if (sc->sc_data_direction == DMA_NONE || !data_len)
 406                 return 0;
 407
 408         scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)
 409                 data_grants += PFN_UP(sg->offset + sg->length);
 410
 411         if (data_grants > VSCSIIF_SG_TABLESIZE) {
 412                 if (data_grants > info->host->sg_tablesize) {
 413                         shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
 414                              "Unable to map request_buffer for command!\n");
 415                         return -E2BIG;
 416                 }
 417                 seg_grants = vscsiif_grants_sg(data_grants);
 418                 shadow->sg = kcalloc(data_grants,
 419                         sizeof(struct scsiif_request_segment), GFP_ATOMIC);
 420                 if (!shadow->sg)
 421                         return -ENOMEM;
 422         }
 423         seg = shadow->sg ? : shadow->seg;
 424
 425         err = gnttab_alloc_grant_references(seg_grants + data_grants,
 426                                             &gref_head);
 427         if (err) {
 428                 kfree(shadow->sg);
 429                 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
 430                              "gnttab_alloc_grant_references() error\n");
 431                 return -ENOMEM;
 432         }
 433
 434         if (seg_grants) {
 435                 page = virt_to_page(seg);
 436                 off = offset_in_page(seg);
 437                 len = sizeof(struct scsiif_request_segment) * data_grants;
 438                 while (len > 0) {
 439                         bytes = min_t(unsigned int, len, PAGE_SIZE - off);
 440
 441                         ref = gnttab_claim_grant_reference(&gref_head);
 442                         BUG_ON(ref == -ENOSPC);
 443
 444                         gnttab_grant_foreign_access_ref(ref,
 445                                 info->dev->otherend_id,
 446                                 xen_page_to_gfn(page), 1);
 447                         shadow->gref[ref_cnt] = ref;
 448                         shadow->seg[ref_cnt].gref   = ref;
 449                         shadow->seg[ref_cnt].offset = (uint16_t)off;
 450                         shadow->seg[ref_cnt].length = (uint16_t)bytes;
 451
 452                         page++;
 453                         len -= bytes;
 454                         off = 0;
 455                         ref_cnt++;
 456                 }
 457                 BUG_ON(seg_grants < ref_cnt);
 458                 seg_grants = ref_cnt;
 459         }
 460
 461         scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {
 462                 page = sg_page(sg);
 463                 off = sg->offset;
 464                 len = sg->length;
 465
 466                 while (len > 0 && data_len > 0) {
 467                         /*
 468                          * sg sends a scatterlist that is larger than
 469                          * the data_len it wants transferred for certain
 470                          * IO sizes.
 471                          */
 472                         bytes = min_t(unsigned int, len, PAGE_SIZE - off);
 473                         bytes = min(bytes, data_len);
 474
 475                         ref = gnttab_claim_grant_reference(&gref_head);
 476                         BUG_ON(ref == -ENOSPC);
 477
 478                         gnttab_grant_foreign_access_ref(ref,
 479                                 info->dev->otherend_id,
 480                                 xen_page_to_gfn(page),
 481                                 grant_ro);
 482
 483                         shadow->gref[ref_cnt] = ref;
 484                         seg->gref   = ref;
 485                         seg->offset = (uint16_t)off;
 486                         seg->length = (uint16_t)bytes;
 487
 488                         page++;
 489                         seg++;
 490                         len -= bytes;
 491                         data_len -= bytes;
 492                         off = 0;
 493                         ref_cnt++;
 494                 }
 495         }
 496
 497         if (seg_grants)
 498                 shadow->nr_segments = VSCSIIF_SG_GRANT | seg_grants;
 499         else
 500                 shadow->nr_segments = (uint8_t)ref_cnt;
 501         shadow->nr_grants = ref_cnt;
 502
 503         return 0;
 504 }
 505
 506 static int scsifront_enter(struct vscsifrnt_info *info)
 507 {
 508         if (info->pause)
 509                 return 1;
 510         info->callers++;
 511         return 0;
 512 }
 513
 514 static void scsifront_return(struct vscsifrnt_info *info)
 515 {
 516         info->callers--;
 517         if (info->callers)
 518                 return;
 519
 520         if (!info->waiting_pause)
 521                 return;
 522
 523         info->waiting_pause = 0;
 524         wake_up(&info->wq_pause);
 525 }
 526
 527 static int scsifront_queuecommand(struct Scsi_Host *shost,
 528                                   struct scsi_cmnd *sc)
 529 {
 530         struct vscsifrnt_info *info = shost_priv(shost);
 531         struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc);
 532         unsigned long flags;
 533         int err;
 534
 535         sc->result = 0;
 536
 537         shadow->sc  = sc;
 538         shadow->act = VSCSIIF_ACT_SCSI_CDB;
 539
 540         spin_lock_irqsave(shost->host_lock, flags);
 541         if (scsifront_enter(info)) {
 542                 spin_unlock_irqrestore(shost->host_lock, flags);
 543                 return SCSI_MLQUEUE_HOST_BUSY;
 544         }
 545
 546         err = map_data_for_request(info, sc, shadow);
 547         if (err < 0) {
 548                 pr_debug("%s: err %d\n", __func__, err);
 549                 scsifront_return(info);
 550                 spin_unlock_irqrestore(shost->host_lock, flags);
 551                 if (err == -ENOMEM)
 552                         return SCSI_MLQUEUE_HOST_BUSY;
 553                 sc->result = DID_ERROR << 16;
 554                 sc->scsi_done(sc);
 555                 return 0;
 556         }
 557
 558         if (scsifront_do_request(info, shadow)) {
 559                 scsifront_gnttab_done(info, shadow);
 560                 goto busy;
 561         }
 562
 563         scsifront_return(info);
 564         spin_unlock_irqrestore(shost->host_lock, flags);
 565
 566         return 0;
 567
 568 busy:
 569         scsifront_return(info);
 570         spin_unlock_irqrestore(shost->host_lock, flags);
 571         pr_debug("%s: busy\n", __func__);
 572         return SCSI_MLQUEUE_HOST_BUSY;
 573 }
 574
 575 /*
 576  * Any exception handling (reset or abort) must be forwarded to the backend.
 577  * We have to wait until an answer is returned. This answer contains the
 578  * result to be returned to the requestor.
 579  */
 580 static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)
 581 {
 582         struct Scsi_Host *host = sc->device->host;
 583         struct vscsifrnt_info *info = shost_priv(host);
 584         struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
 585         int err = 0;
 586
 587         shadow = kzalloc(sizeof(*shadow), GFP_NOIO);
 588         if (!shadow)
 589                 return FAILED;
 590
 591         shadow->act = act;
 592         shadow->rslt_reset = RSLT_RESET_WAITING;
 593         shadow->sc = sc;
 594         shadow->ref_rqid = s->rqid;
 595         init_waitqueue_head(&shadow->wq_reset);
 596
 597         spin_lock_irq(host->host_lock);
 598
 599         for (;;) {
 600                 if (scsifront_enter(info))
 601                         goto fail;
 602
 603                 if (!scsifront_do_request(info, shadow))
 604                         break;
 605
 606                 scsifront_return(info);
 607                 if (err)
 608                         goto fail;
 609                 info->wait_ring_available = 1;
 610                 spin_unlock_irq(host->host_lock);
 611                 err = wait_event_interruptible(info->wq_sync,
 612                                                !info->wait_ring_available);
 613                 spin_lock_irq(host->host_lock);
 614         }
 615
 616         spin_unlock_irq(host->host_lock);
 617         err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
 618         spin_lock_irq(host->host_lock);
 619
 620         if (!err) {
 621                 err = shadow->rslt_reset;
 622                 scsifront_put_rqid(info, shadow->rqid);
 623                 kfree(shadow);
 624         } else {
 625                 spin_lock(&info->shadow_lock);
 626                 shadow->rslt_reset = RSLT_RESET_ERR;
 627                 spin_unlock(&info->shadow_lock);
 628                 err = FAILED;
 629         }
 630
 631         scsifront_return(info);
 632         spin_unlock_irq(host->host_lock);
 633         return err;
 634
 635 fail:
 636         spin_unlock_irq(host->host_lock);
 637         kfree(shadow);
 638         return FAILED;
 639 }
 640
 641 static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
 642 {
 643         pr_debug("%s\n", __func__);
 644         return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);
 645 }
 646
 647 static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
 648 {
 649         pr_debug("%s\n", __func__);
 650         return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);
 651 }
 652
 653 static int scsifront_sdev_configure(struct scsi_device *sdev)
 654 {
 655         struct vscsifrnt_info *info = shost_priv(sdev->host);
 656         int err;
 657
 658         if (info && current == info->curr) {
 659                 err = xenbus_printf(XBT_NIL, info->dev->nodename,
 660                               info->dev_state_path, "%d", XenbusStateConnected);
 661                 if (err) {
 662                         xenbus_dev_error(info->dev, err,
 663                                 "%s: writing dev_state_path", __func__);
 664                         return err;
 665                 }
 666         }
 667
 668         return 0;
 669 }
 670
 671 static void scsifront_sdev_destroy(struct scsi_device *sdev)
 672 {
 673         struct vscsifrnt_info *info = shost_priv(sdev->host);
 674         int err;
 675
 676         if (info && current == info->curr) {
 677                 err = xenbus_printf(XBT_NIL, info->dev->nodename,
 678                               info->dev_state_path, "%d", XenbusStateClosed);
 679                 if (err)
 680                         xenbus_dev_error(info->dev, err,
 681                                 "%s: writing dev_state_path", __func__);
 682         }
 683 }
 684
 685 static struct scsi_host_template scsifront_sht = {
 686         .module                 = THIS_MODULE,
 687         .name                   = "Xen SCSI frontend driver",
 688         .queuecommand           = scsifront_queuecommand,
 689         .eh_abort_handler       = scsifront_eh_abort_handler,
 690         .eh_device_reset_handler = scsifront_dev_reset_handler,
 691         .slave_configure        = scsifront_sdev_configure,
 692         .slave_destroy          = scsifront_sdev_destroy,
 693         .cmd_per_lun            = VSCSIIF_DEFAULT_CMD_PER_LUN,
 694         .can_queue              = VSCSIIF_MAX_REQS,
 695         .this_id                = -1,
 696         .cmd_size               = sizeof(struct vscsifrnt_shadow),
 697         .sg_tablesize           = VSCSIIF_SG_TABLESIZE,
 698         .proc_name              = "scsifront",
 699 };
 700
 701 static int scsifront_alloc_ring(struct vscsifrnt_info *info)
 702 {
 703         struct xenbus_device *dev = info->dev;
 704         struct vscsiif_sring *sring;
 705         grant_ref_t gref;
 706         int err = -ENOMEM;
 707
 708         /***** Frontend to Backend ring start *****/
 709         sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL);
 710         if (!sring) {
 711                 xenbus_dev_fatal(dev, err,
 712                         "fail to allocate shared ring (Front to Back)");
 713                 return err;
 714         }
 715         SHARED_RING_INIT(sring);
 716         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 717
 718         err = xenbus_grant_ring(dev, sring, 1, &gref);
 719         if (err < 0) {
 720                 free_page((unsigned long)sring);
 721                 xenbus_dev_fatal(dev, err,
 722                         "fail to grant shared ring (Front to Back)");
 723                 return err;
 724         }
 725         info->ring_ref = gref;
 726
 727         err = xenbus_alloc_evtchn(dev, &info->evtchn);
 728         if (err) {
 729                 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
 730                 goto free_gnttab;
 731         }
 732
 733         err = bind_evtchn_to_irq(info->evtchn);
 734         if (err <= 0) {
 735                 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
 736                 goto free_gnttab;
 737         }
 738
 739         info->irq = err;
 740
 741         err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
 742                                    IRQF_ONESHOT, "scsifront", info);
 743         if (err) {
 744                 xenbus_dev_fatal(dev, err, "request_threaded_irq");
 745                 goto free_irq;
 746         }
 747
 748         return 0;
 749
 750 /* free resource */
 751 free_irq:
 752         unbind_from_irqhandler(info->irq, info);
 753 free_gnttab:
 754         gnttab_end_foreign_access(info->ring_ref, 0,
 755                                   (unsigned long)info->ring.sring);
 756
 757         return err;
 758 }
 759
 760 static void scsifront_free_ring(struct vscsifrnt_info *info)
 761 {
 762         unbind_from_irqhandler(info->irq, info);
 763         gnttab_end_foreign_access(info->ring_ref, 0,
 764                                   (unsigned long)info->ring.sring);
 765 }
 766
 767 static int scsifront_init_ring(struct vscsifrnt_info *info)
 768 {
 769         struct xenbus_device *dev = info->dev;
 770         struct xenbus_transaction xbt;
 771         int err;
 772
 773         pr_debug("%s\n", __func__);
 774
 775         err = scsifront_alloc_ring(info);
 776         if (err)
 777                 return err;
 778         pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
 779
 780 again:
 781         err = xenbus_transaction_start(&xbt);
 782         if (err)
 783                 xenbus_dev_fatal(dev, err, "starting transaction");
 784
 785         err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
 786                             info->ring_ref);
 787         if (err) {
 788                 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
 789                 goto fail;
 790         }
 791
 792         err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
 793                             info->evtchn);
 794
 795         if (err) {
 796                 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
 797                 goto fail;
 798         }
 799
 800         err = xenbus_transaction_end(xbt, 0);
 801         if (err) {
 802                 if (err == -EAGAIN)
 803                         goto again;
 804                 xenbus_dev_fatal(dev, err, "completing transaction");
 805                 goto free_sring;
 806         }
 807
 808         return 0;
 809
 810 fail:
 811         xenbus_transaction_end(xbt, 1);
 812 free_sring:
 813         scsifront_free_ring(info);
 814
 815         return err;
 816 }
 817
 818
 819 static int scsifront_probe(struct xenbus_device *dev,
 820                            const struct xenbus_device_id *id)
 821 {
 822         struct vscsifrnt_info *info;
 823         struct Scsi_Host *host;
 824         int err = -ENOMEM;
 825         char name[TASK_COMM_LEN];
 826
 827         host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
 828         if (!host) {
 829                 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
 830                 return err;
 831         }
 832         info = (struct vscsifrnt_info *)host->hostdata;
 833
 834         dev_set_drvdata(&dev->dev, info);
 835         info->dev = dev;
 836
 837         bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
 838
 839         err = scsifront_init_ring(info);
 840         if (err) {
 841                 scsi_host_put(host);
 842                 return err;
 843         }
 844
 845         init_waitqueue_head(&info->wq_sync);
 846         init_waitqueue_head(&info->wq_pause);
 847         spin_lock_init(&info->shadow_lock);
 848
 849         snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
 850
 851         host->max_id      = VSCSIIF_MAX_TARGET;
 852         host->max_channel = 0;
 853         host->max_lun     = VSCSIIF_MAX_LUN;
 854         host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
 855         host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
 856
 857         err = scsi_add_host(host, &dev->dev);
 858         if (err) {
 859                 dev_err(&dev->dev, "fail to add scsi host %d\n", err);
 860                 goto free_sring;
 861         }
 862         info->host = host;
 863         info->host_active = 1;
 864
 865         xenbus_switch_state(dev, XenbusStateInitialised);
 866
 867         return 0;
 868
 869 free_sring:
 870         scsifront_free_ring(info);
 871         scsi_host_put(host);
 872         return err;
 873 }
 874
 875 static int scsifront_resume(struct xenbus_device *dev)
 876 {
 877         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 878         struct Scsi_Host *host = info->host;
 879         int err;
 880
 881         spin_lock_irq(host->host_lock);
 882
 883         /* Finish all still pending commands. */
 884         scsifront_finish_all(info);
 885
 886         spin_unlock_irq(host->host_lock);
 887
 888         /* Reconnect to dom0. */
 889         scsifront_free_ring(info);
 890         err = scsifront_init_ring(info);
 891         if (err) {
 892                 dev_err(&dev->dev, "fail to resume %d\n", err);
 893                 scsi_host_put(host);
 894                 return err;
 895         }
 896
 897         xenbus_switch_state(dev, XenbusStateInitialised);
 898
 899         return 0;
 900 }
 901
 902 static int scsifront_suspend(struct xenbus_device *dev)
 903 {
 904         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 905         struct Scsi_Host *host = info->host;
 906         int err = 0;
 907
 908         /* No new commands for the backend. */
 909         spin_lock_irq(host->host_lock);
 910         info->pause = 1;
 911         while (info->callers && !err) {
 912                 info->waiting_pause = 1;
 913                 info->wait_ring_available = 0;
 914                 spin_unlock_irq(host->host_lock);
 915                 wake_up(&info->wq_sync);
 916                 err = wait_event_interruptible(info->wq_pause,
 917                                                !info->waiting_pause);
 918                 spin_lock_irq(host->host_lock);
 919         }
 920         spin_unlock_irq(host->host_lock);
 921         return err;
 922 }
 923
 924 static int scsifront_remove(struct xenbus_device *dev)
 925 {
 926         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 927
 928         pr_debug("%s: %s removed\n", __func__, dev->nodename);
 929
 930         mutex_lock(&scsifront_mutex);
 931         if (info->host_active) {
 932                 /* Scsi_host not yet removed */
 933                 scsi_remove_host(info->host);
 934                 info->host_active = 0;
 935         }
 936         mutex_unlock(&scsifront_mutex);
 937
 938         scsifront_free_ring(info);
 939         scsi_host_put(info->host);
 940
 941         return 0;
 942 }
 943
 944 static void scsifront_disconnect(struct vscsifrnt_info *info)
 945 {
 946         struct xenbus_device *dev = info->dev;
 947         struct Scsi_Host *host = info->host;
 948
 949         pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
 950
 951         /*
 952          * When this function is executed, all devices of
 953          * Frontend have been deleted.
 954          * Therefore, it need not block I/O before remove_host.
 955          */
 956
 957         mutex_lock(&scsifront_mutex);
 958         if (info->host_active) {
 959                 scsi_remove_host(host);
 960                 info->host_active = 0;
 961         }
 962         mutex_unlock(&scsifront_mutex);
 963
 964         xenbus_frontend_closed(dev);
 965 }
 966
 967 static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
 968 {
 969         struct xenbus_device *dev = info->dev;
 970         int i, err = 0;
 971         char str[64];
 972         char **dir;
 973         unsigned int dir_n = 0;
 974         unsigned int device_state;
 975         unsigned int hst, chn, tgt, lun;
 976         struct scsi_device *sdev;
 977
 978         dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
 979         if (IS_ERR(dir))
 980                 return;
 981
 982         /* mark current task as the one allowed to modify device states */
 983         BUG_ON(info->curr);
 984         info->curr = current;
 985
 986         for (i = 0; i < dir_n; i++) {
 987                 /* read status */
 988                 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
 989                 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
 990                                    &device_state);
 991                 if (XENBUS_EXIST_ERR(err))
 992                         continue;
 993
 994                 /* virtual SCSI device */
 995                 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
 996                 err = xenbus_scanf(XBT_NIL, dev->otherend, str,
 997                                    "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
 998                 if (XENBUS_EXIST_ERR(err))
 999                         continue;
1000
1001                 /*
1002                  * Front device state path, used in slave_configure called
1003                  * on successfull scsi_add_device, and in slave_destroy called
1004                  * on remove of a device.
1005                  */
1006                 snprintf(info->dev_state_path, sizeof(info->dev_state_path),
1007                          "vscsi-devs/%s/state", dir[i]);
1008
1009                 switch (op) {
1010                 case VSCSIFRONT_OP_ADD_LUN:
1011                         if (device_state != XenbusStateInitialised)
1012                                 break;
1013
1014                         if (scsi_add_device(info->host, chn, tgt, lun)) {
1015                                 dev_err(&dev->dev, "scsi_add_device\n");
1016                                 err = xenbus_printf(XBT_NIL, dev->nodename,
1017                                               info->dev_state_path,
1018                                               "%d", XenbusStateClosed);
1019                                 if (err)
1020                                         xenbus_dev_error(dev, err,
1021                                                 "%s: writing dev_state_path", __func__);
1022                         }
1023                         break;
1024                 case VSCSIFRONT_OP_DEL_LUN:
1025                         if (device_state != XenbusStateClosing)
1026                                 break;
1027
1028                         sdev = scsi_device_lookup(info->host, chn, tgt, lun);
1029                         if (sdev) {
1030                                 scsi_remove_device(sdev);
1031                                 scsi_device_put(sdev);
1032                         }
1033                         break;
1034                 case VSCSIFRONT_OP_READD_LUN:
1035                         if (device_state == XenbusStateConnected) {
1036                                 err = xenbus_printf(XBT_NIL, dev->nodename,
1037                                               info->dev_state_path,
1038                                               "%d", XenbusStateConnected);
1039                                 if (err)
1040                                         xenbus_dev_error(dev, err,
1041                                                 "%s: writing dev_state_path", __func__);
1042                         }
1043                         break;
1044                 default:
1045                         break;
1046                 }
1047         }
1048
1049         info->curr = NULL;
1050
1051         kfree(dir);
1052 }
1053
1054 static void scsifront_read_backend_params(struct xenbus_device *dev,
1055                                           struct vscsifrnt_info *info)
1056 {
1057         unsigned int sg_grant, nr_segs;
1058         struct Scsi_Host *host = info->host;
1059
1060         sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0);
1061         nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
1062         nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
1063         nr_segs = min_t(unsigned int, nr_segs,
1064                         VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
1065                         sizeof(struct scsiif_request_segment));
1066
1067         if (!info->pause && sg_grant)
1068                 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);
1069         else if (info->pause && nr_segs < host->sg_tablesize)
1070                 dev_warn(&dev->dev,
1071                          "SG entries decreased from %d to %u - device may not work properly anymore\n",
1072                          host->sg_tablesize, nr_segs);
1073
1074         host->sg_tablesize = nr_segs;
1075         host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;
1076 }
1077
1078 static void scsifront_backend_changed(struct xenbus_device *dev,
1079                                       enum xenbus_state backend_state)
1080 {
1081         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1082
1083         pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
1084
1085         switch (backend_state) {
1086         case XenbusStateUnknown:
1087         case XenbusStateInitialising:
1088         case XenbusStateInitWait:
1089         case XenbusStateInitialised:
1090                 break;
1091
1092         case XenbusStateConnected:
1093                 scsifront_read_backend_params(dev, info);
1094
1095                 if (info->pause) {
1096                         scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);
1097                         xenbus_switch_state(dev, XenbusStateConnected);
1098                         info->pause = 0;
1099                         return;
1100                 }
1101
1102                 if (xenbus_read_driver_state(dev->nodename) ==
1103                     XenbusStateInitialised)
1104                         scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1105
1106                 if (dev->state != XenbusStateConnected)
1107                         xenbus_switch_state(dev, XenbusStateConnected);
1108                 break;
1109
1110         case XenbusStateClosed:
1111                 if (dev->state == XenbusStateClosed)
1112                         break;
1113                 fallthrough;    /* Missed the backend's Closing state */
1114         case XenbusStateClosing:
1115                 scsifront_disconnect(info);
1116                 break;
1117
1118         case XenbusStateReconfiguring:
1119                 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
1120                 xenbus_switch_state(dev, XenbusStateReconfiguring);
1121                 break;
1122
1123         case XenbusStateReconfigured:
1124                 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1125                 xenbus_switch_state(dev, XenbusStateConnected);
1126                 break;
1127         }
1128 }
1129
1130 static const struct xenbus_device_id scsifront_ids[] = {
1131         { "vscsi" },
1132         { "" }
1133 };
1134
1135 static struct xenbus_driver scsifront_driver = {
1136         .ids                    = scsifront_ids,
1137         .probe                  = scsifront_probe,
1138         .remove                 = scsifront_remove,
1139         .resume                 = scsifront_resume,
1140         .suspend                = scsifront_suspend,
1141         .otherend_changed       = scsifront_backend_changed,
1142 };
1143
1144 static int __init scsifront_init(void)
1145 {
1146         if (!xen_domain())
1147                 return -ENODEV;
1148
1149         return xenbus_register_frontend(&scsifront_driver);
1150 }
1151 module_init(scsifront_init);
1152
1153 static void __exit scsifront_exit(void)
1154 {
1155         xenbus_unregister_driver(&scsifront_driver);
1156 }
1157 module_exit(scsifront_exit);
1158
1159 MODULE_DESCRIPTION("Xen SCSI frontend driver");
1160 MODULE_LICENSE("GPL");
1161 MODULE_ALIAS("xen:vscsi");
1162 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");