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_query_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                 gnttab_end_foreign_access(shadow->gref[i], 0, 0UL);
 242         }
 243
 244         kfree(shadow->sg);
 245 }
 246
 247 static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info,
 248                                    struct vscsiif_response *ring_rsp)
 249 {
 250         struct vscsifrnt_shadow *shadow;
 251         struct scsi_cmnd *sc;
 252         uint32_t id;
 253         uint8_t sense_len;
 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         sc->result = ring_rsp->rslt;
 265         scsi_set_resid(sc, ring_rsp->residual_len);
 266
 267         sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE,
 268                           ring_rsp->sense_len);
 269
 270         if (sense_len)
 271                 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len);
 272
 273         sc->scsi_done(sc);
 274 }
 275
 276 static void scsifront_sync_cmd_done(struct vscsifrnt_info *info,
 277                                     struct vscsiif_response *ring_rsp)
 278 {
 279         uint16_t id = ring_rsp->rqid;
 280         unsigned long flags;
 281         struct vscsifrnt_shadow *shadow = info->shadow[id];
 282         int kick;
 283
 284         spin_lock_irqsave(&info->shadow_lock, flags);
 285         shadow->wait_reset = 1;
 286         switch (shadow->rslt_reset) {
 287         case RSLT_RESET_WAITING:
 288                 shadow->rslt_reset = ring_rsp->rslt;
 289                 break;
 290         case RSLT_RESET_ERR:
 291                 kick = _scsifront_put_rqid(info, id);
 292                 spin_unlock_irqrestore(&info->shadow_lock, flags);
 293                 kfree(shadow);
 294                 if (kick)
 295                         scsifront_wake_up(info);
 296                 return;
 297         default:
 298                 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
 299                              "bad reset state %d, possibly leaking %u\n",
 300                              shadow->rslt_reset, id);
 301                 break;
 302         }
 303         spin_unlock_irqrestore(&info->shadow_lock, flags);
 304
 305         wake_up(&shadow->wq_reset);
 306 }
 307
 308 static void scsifront_do_response(struct vscsifrnt_info *info,
 309                                   struct vscsiif_response *ring_rsp)
 310 {
 311         if (WARN(ring_rsp->rqid >= VSCSIIF_MAX_REQS ||
 312                  test_bit(ring_rsp->rqid, info->shadow_free_bitmap),
 313                  "illegal rqid %u returned by backend!\n", ring_rsp->rqid))
 314                 return;
 315
 316         if (info->shadow[ring_rsp->rqid]->act == VSCSIIF_ACT_SCSI_CDB)
 317                 scsifront_cdb_cmd_done(info, ring_rsp);
 318         else
 319                 scsifront_sync_cmd_done(info, ring_rsp);
 320 }
 321
 322 static int scsifront_ring_drain(struct vscsifrnt_info *info)
 323 {
 324         struct vscsiif_response *ring_rsp;
 325         RING_IDX i, rp;
 326         int more_to_do = 0;
 327
 328         rp = info->ring.sring->rsp_prod;
 329         rmb();  /* ordering required respective to dom0 */
 330         for (i = info->ring.rsp_cons; i != rp; i++) {
 331                 ring_rsp = RING_GET_RESPONSE(&info->ring, i);
 332                 scsifront_do_response(info, ring_rsp);
 333         }
 334
 335         info->ring.rsp_cons = i;
 336
 337         if (i != info->ring.req_prod_pvt)
 338                 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
 339         else
 340                 info->ring.sring->rsp_event = i + 1;
 341
 342         return more_to_do;
 343 }
 344
 345 static int scsifront_cmd_done(struct vscsifrnt_info *info)
 346 {
 347         int more_to_do;
 348         unsigned long flags;
 349
 350         spin_lock_irqsave(info->host->host_lock, flags);
 351
 352         more_to_do = scsifront_ring_drain(info);
 353
 354         info->wait_ring_available = 0;
 355
 356         spin_unlock_irqrestore(info->host->host_lock, flags);
 357
 358         wake_up(&info->wq_sync);
 359
 360         return more_to_do;
 361 }
 362
 363 static irqreturn_t scsifront_irq_fn(int irq, void *dev_id)
 364 {
 365         struct vscsifrnt_info *info = dev_id;
 366
 367         while (scsifront_cmd_done(info))
 368                 /* Yield point for this unbounded loop. */
 369                 cond_resched();
 370
 371         return IRQ_HANDLED;
 372 }
 373
 374 static void scsifront_finish_all(struct vscsifrnt_info *info)
 375 {
 376         unsigned i;
 377         struct vscsiif_response resp;
 378
 379         scsifront_ring_drain(info);
 380
 381         for (i = 0; i < VSCSIIF_MAX_REQS; i++) {
 382                 if (test_bit(i, info->shadow_free_bitmap))
 383                         continue;
 384                 resp.rqid = i;
 385                 resp.sense_len = 0;
 386                 resp.rslt = DID_RESET << 16;
 387                 resp.residual_len = 0;
 388                 scsifront_do_response(info, &resp);
 389         }
 390 }
 391
 392 static int map_data_for_request(struct vscsifrnt_info *info,
 393                                 struct scsi_cmnd *sc,
 394                                 struct vscsifrnt_shadow *shadow)
 395 {
 396         grant_ref_t gref_head;
 397         struct page *page;
 398         int err, ref, ref_cnt = 0;
 399         int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE);
 400         unsigned int i, off, len, bytes;
 401         unsigned int data_len = scsi_bufflen(sc);
 402         unsigned int data_grants = 0, seg_grants = 0;
 403         struct scatterlist *sg;
 404         struct scsiif_request_segment *seg;
 405
 406         if (sc->sc_data_direction == DMA_NONE || !data_len)
 407                 return 0;
 408
 409         scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)
 410                 data_grants += PFN_UP(sg->offset + sg->length);
 411
 412         if (data_grants > VSCSIIF_SG_TABLESIZE) {
 413                 if (data_grants > info->host->sg_tablesize) {
 414                         shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
 415                              "Unable to map request_buffer for command!\n");
 416                         return -E2BIG;
 417                 }
 418                 seg_grants = vscsiif_grants_sg(data_grants);
 419                 shadow->sg = kcalloc(data_grants,
 420                         sizeof(struct scsiif_request_segment), GFP_ATOMIC);
 421                 if (!shadow->sg)
 422                         return -ENOMEM;
 423         }
 424         seg = shadow->sg ? : shadow->seg;
 425
 426         err = gnttab_alloc_grant_references(seg_grants + data_grants,
 427                                             &gref_head);
 428         if (err) {
 429                 kfree(shadow->sg);
 430                 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
 431                              "gnttab_alloc_grant_references() error\n");
 432                 return -ENOMEM;
 433         }
 434
 435         if (seg_grants) {
 436                 page = virt_to_page(seg);
 437                 off = offset_in_page(seg);
 438                 len = sizeof(struct scsiif_request_segment) * data_grants;
 439                 while (len > 0) {
 440                         bytes = min_t(unsigned int, len, PAGE_SIZE - off);
 441
 442                         ref = gnttab_claim_grant_reference(&gref_head);
 443                         BUG_ON(ref == -ENOSPC);
 444
 445                         gnttab_grant_foreign_access_ref(ref,
 446                                 info->dev->otherend_id,
 447                                 xen_page_to_gfn(page), 1);
 448                         shadow->gref[ref_cnt] = ref;
 449                         shadow->seg[ref_cnt].gref   = ref;
 450                         shadow->seg[ref_cnt].offset = (uint16_t)off;
 451                         shadow->seg[ref_cnt].length = (uint16_t)bytes;
 452
 453                         page++;
 454                         len -= bytes;
 455                         off = 0;
 456                         ref_cnt++;
 457                 }
 458                 BUG_ON(seg_grants < ref_cnt);
 459                 seg_grants = ref_cnt;
 460         }
 461
 462         scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {
 463                 page = sg_page(sg);
 464                 off = sg->offset;
 465                 len = sg->length;
 466
 467                 while (len > 0 && data_len > 0) {
 468                         /*
 469                          * sg sends a scatterlist that is larger than
 470                          * the data_len it wants transferred for certain
 471                          * IO sizes.
 472                          */
 473                         bytes = min_t(unsigned int, len, PAGE_SIZE - off);
 474                         bytes = min(bytes, data_len);
 475
 476                         ref = gnttab_claim_grant_reference(&gref_head);
 477                         BUG_ON(ref == -ENOSPC);
 478
 479                         gnttab_grant_foreign_access_ref(ref,
 480                                 info->dev->otherend_id,
 481                                 xen_page_to_gfn(page),
 482                                 grant_ro);
 483
 484                         shadow->gref[ref_cnt] = ref;
 485                         seg->gref   = ref;
 486                         seg->offset = (uint16_t)off;
 487                         seg->length = (uint16_t)bytes;
 488
 489                         page++;
 490                         seg++;
 491                         len -= bytes;
 492                         data_len -= bytes;
 493                         off = 0;
 494                         ref_cnt++;
 495                 }
 496         }
 497
 498         if (seg_grants)
 499                 shadow->nr_segments = VSCSIIF_SG_GRANT | seg_grants;
 500         else
 501                 shadow->nr_segments = (uint8_t)ref_cnt;
 502         shadow->nr_grants = ref_cnt;
 503
 504         return 0;
 505 }
 506
 507 static int scsifront_enter(struct vscsifrnt_info *info)
 508 {
 509         if (info->pause)
 510                 return 1;
 511         info->callers++;
 512         return 0;
 513 }
 514
 515 static void scsifront_return(struct vscsifrnt_info *info)
 516 {
 517         info->callers--;
 518         if (info->callers)
 519                 return;
 520
 521         if (!info->waiting_pause)
 522                 return;
 523
 524         info->waiting_pause = 0;
 525         wake_up(&info->wq_pause);
 526 }
 527
 528 static int scsifront_queuecommand(struct Scsi_Host *shost,
 529                                   struct scsi_cmnd *sc)
 530 {
 531         struct vscsifrnt_info *info = shost_priv(shost);
 532         struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc);
 533         unsigned long flags;
 534         int err;
 535
 536         sc->result = 0;
 537         memset(shadow, 0, sizeof(*shadow));
 538
 539         shadow->sc  = sc;
 540         shadow->act = VSCSIIF_ACT_SCSI_CDB;
 541
 542         spin_lock_irqsave(shost->host_lock, flags);
 543         if (scsifront_enter(info)) {
 544                 spin_unlock_irqrestore(shost->host_lock, flags);
 545                 return SCSI_MLQUEUE_HOST_BUSY;
 546         }
 547
 548         err = map_data_for_request(info, sc, shadow);
 549         if (err < 0) {
 550                 pr_debug("%s: err %d\n", __func__, err);
 551                 scsifront_return(info);
 552                 spin_unlock_irqrestore(shost->host_lock, flags);
 553                 if (err == -ENOMEM)
 554                         return SCSI_MLQUEUE_HOST_BUSY;
 555                 sc->result = DID_ERROR << 16;
 556                 sc->scsi_done(sc);
 557                 return 0;
 558         }
 559
 560         if (scsifront_do_request(info, shadow)) {
 561                 scsifront_gnttab_done(info, shadow);
 562                 goto busy;
 563         }
 564
 565         scsifront_return(info);
 566         spin_unlock_irqrestore(shost->host_lock, flags);
 567
 568         return 0;
 569
 570 busy:
 571         scsifront_return(info);
 572         spin_unlock_irqrestore(shost->host_lock, flags);
 573         pr_debug("%s: busy\n", __func__);
 574         return SCSI_MLQUEUE_HOST_BUSY;
 575 }
 576
 577 /*
 578  * Any exception handling (reset or abort) must be forwarded to the backend.
 579  * We have to wait until an answer is returned. This answer contains the
 580  * result to be returned to the requestor.
 581  */
 582 static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)
 583 {
 584         struct Scsi_Host *host = sc->device->host;
 585         struct vscsifrnt_info *info = shost_priv(host);
 586         struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
 587         int err = 0;
 588
 589         shadow = kzalloc(sizeof(*shadow), GFP_NOIO);
 590         if (!shadow)
 591                 return FAILED;
 592
 593         shadow->act = act;
 594         shadow->rslt_reset = RSLT_RESET_WAITING;
 595         shadow->sc = sc;
 596         shadow->ref_rqid = s->rqid;
 597         init_waitqueue_head(&shadow->wq_reset);
 598
 599         spin_lock_irq(host->host_lock);
 600
 601         for (;;) {
 602                 if (scsifront_enter(info))
 603                         goto fail;
 604
 605                 if (!scsifront_do_request(info, shadow))
 606                         break;
 607
 608                 scsifront_return(info);
 609                 if (err)
 610                         goto fail;
 611                 info->wait_ring_available = 1;
 612                 spin_unlock_irq(host->host_lock);
 613                 err = wait_event_interruptible(info->wq_sync,
 614                                                !info->wait_ring_available);
 615                 spin_lock_irq(host->host_lock);
 616         }
 617
 618         spin_unlock_irq(host->host_lock);
 619         err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
 620         spin_lock_irq(host->host_lock);
 621
 622         if (!err) {
 623                 err = shadow->rslt_reset;
 624                 scsifront_put_rqid(info, shadow->rqid);
 625                 kfree(shadow);
 626         } else {
 627                 spin_lock(&info->shadow_lock);
 628                 shadow->rslt_reset = RSLT_RESET_ERR;
 629                 spin_unlock(&info->shadow_lock);
 630                 err = FAILED;
 631         }
 632
 633         scsifront_return(info);
 634         spin_unlock_irq(host->host_lock);
 635         return err;
 636
 637 fail:
 638         spin_unlock_irq(host->host_lock);
 639         kfree(shadow);
 640         return FAILED;
 641 }
 642
 643 static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
 644 {
 645         pr_debug("%s\n", __func__);
 646         return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);
 647 }
 648
 649 static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
 650 {
 651         pr_debug("%s\n", __func__);
 652         return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);
 653 }
 654
 655 static int scsifront_sdev_configure(struct scsi_device *sdev)
 656 {
 657         struct vscsifrnt_info *info = shost_priv(sdev->host);
 658
 659         if (info && current == info->curr)
 660                 xenbus_printf(XBT_NIL, info->dev->nodename,
 661                               info->dev_state_path, "%d", XenbusStateConnected);
 662
 663         return 0;
 664 }
 665
 666 static void scsifront_sdev_destroy(struct scsi_device *sdev)
 667 {
 668         struct vscsifrnt_info *info = shost_priv(sdev->host);
 669
 670         if (info && current == info->curr)
 671                 xenbus_printf(XBT_NIL, info->dev->nodename,
 672                               info->dev_state_path, "%d", XenbusStateClosed);
 673 }
 674
 675 static struct scsi_host_template scsifront_sht = {
 676         .module                 = THIS_MODULE,
 677         .name                   = "Xen SCSI frontend driver",
 678         .queuecommand           = scsifront_queuecommand,
 679         .eh_abort_handler       = scsifront_eh_abort_handler,
 680         .eh_device_reset_handler = scsifront_dev_reset_handler,
 681         .slave_configure        = scsifront_sdev_configure,
 682         .slave_destroy          = scsifront_sdev_destroy,
 683         .cmd_per_lun            = VSCSIIF_DEFAULT_CMD_PER_LUN,
 684         .can_queue              = VSCSIIF_MAX_REQS,
 685         .this_id                = -1,
 686         .cmd_size               = sizeof(struct vscsifrnt_shadow),
 687         .sg_tablesize           = VSCSIIF_SG_TABLESIZE,
 688         .use_clustering         = DISABLE_CLUSTERING,
 689         .proc_name              = "scsifront",
 690 };
 691
 692 static int scsifront_alloc_ring(struct vscsifrnt_info *info)
 693 {
 694         struct xenbus_device *dev = info->dev;
 695         struct vscsiif_sring *sring;
 696         grant_ref_t gref;
 697         int err = -ENOMEM;
 698
 699         /***** Frontend to Backend ring start *****/
 700         sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL);
 701         if (!sring) {
 702                 xenbus_dev_fatal(dev, err,
 703                         "fail to allocate shared ring (Front to Back)");
 704                 return err;
 705         }
 706         SHARED_RING_INIT(sring);
 707         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 708
 709         err = xenbus_grant_ring(dev, sring, 1, &gref);
 710         if (err < 0) {
 711                 free_page((unsigned long)sring);
 712                 xenbus_dev_fatal(dev, err,
 713                         "fail to grant shared ring (Front to Back)");
 714                 return err;
 715         }
 716         info->ring_ref = gref;
 717
 718         err = xenbus_alloc_evtchn(dev, &info->evtchn);
 719         if (err) {
 720                 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
 721                 goto free_gnttab;
 722         }
 723
 724         err = bind_evtchn_to_irq(info->evtchn);
 725         if (err <= 0) {
 726                 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
 727                 goto free_gnttab;
 728         }
 729
 730         info->irq = err;
 731
 732         err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
 733                                    IRQF_ONESHOT, "scsifront", info);
 734         if (err) {
 735                 xenbus_dev_fatal(dev, err, "request_threaded_irq");
 736                 goto free_irq;
 737         }
 738
 739         return 0;
 740
 741 /* free resource */
 742 free_irq:
 743         unbind_from_irqhandler(info->irq, info);
 744 free_gnttab:
 745         gnttab_end_foreign_access(info->ring_ref, 0,
 746                                   (unsigned long)info->ring.sring);
 747
 748         return err;
 749 }
 750
 751 static void scsifront_free_ring(struct vscsifrnt_info *info)
 752 {
 753         unbind_from_irqhandler(info->irq, info);
 754         gnttab_end_foreign_access(info->ring_ref, 0,
 755                                   (unsigned long)info->ring.sring);
 756 }
 757
 758 static int scsifront_init_ring(struct vscsifrnt_info *info)
 759 {
 760         struct xenbus_device *dev = info->dev;
 761         struct xenbus_transaction xbt;
 762         int err;
 763
 764         pr_debug("%s\n", __func__);
 765
 766         err = scsifront_alloc_ring(info);
 767         if (err)
 768                 return err;
 769         pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
 770
 771 again:
 772         err = xenbus_transaction_start(&xbt);
 773         if (err)
 774                 xenbus_dev_fatal(dev, err, "starting transaction");
 775
 776         err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
 777                             info->ring_ref);
 778         if (err) {
 779                 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
 780                 goto fail;
 781         }
 782
 783         err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
 784                             info->evtchn);
 785
 786         if (err) {
 787                 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
 788                 goto fail;
 789         }
 790
 791         err = xenbus_transaction_end(xbt, 0);
 792         if (err) {
 793                 if (err == -EAGAIN)
 794                         goto again;
 795                 xenbus_dev_fatal(dev, err, "completing transaction");
 796                 goto free_sring;
 797         }
 798
 799         return 0;
 800
 801 fail:
 802         xenbus_transaction_end(xbt, 1);
 803 free_sring:
 804         scsifront_free_ring(info);
 805
 806         return err;
 807 }
 808
 809
 810 static int scsifront_probe(struct xenbus_device *dev,
 811                            const struct xenbus_device_id *id)
 812 {
 813         struct vscsifrnt_info *info;
 814         struct Scsi_Host *host;
 815         int err = -ENOMEM;
 816         char name[TASK_COMM_LEN];
 817
 818         host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
 819         if (!host) {
 820                 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
 821                 return err;
 822         }
 823         info = (struct vscsifrnt_info *)host->hostdata;
 824
 825         dev_set_drvdata(&dev->dev, info);
 826         info->dev = dev;
 827
 828         bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
 829
 830         err = scsifront_init_ring(info);
 831         if (err) {
 832                 scsi_host_put(host);
 833                 return err;
 834         }
 835
 836         init_waitqueue_head(&info->wq_sync);
 837         init_waitqueue_head(&info->wq_pause);
 838         spin_lock_init(&info->shadow_lock);
 839
 840         snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
 841
 842         host->max_id      = VSCSIIF_MAX_TARGET;
 843         host->max_channel = 0;
 844         host->max_lun     = VSCSIIF_MAX_LUN;
 845         host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
 846         host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
 847
 848         err = scsi_add_host(host, &dev->dev);
 849         if (err) {
 850                 dev_err(&dev->dev, "fail to add scsi host %d\n", err);
 851                 goto free_sring;
 852         }
 853         info->host = host;
 854         info->host_active = 1;
 855
 856         xenbus_switch_state(dev, XenbusStateInitialised);
 857
 858         return 0;
 859
 860 free_sring:
 861         scsifront_free_ring(info);
 862         scsi_host_put(host);
 863         return err;
 864 }
 865
 866 static int scsifront_resume(struct xenbus_device *dev)
 867 {
 868         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 869         struct Scsi_Host *host = info->host;
 870         int err;
 871
 872         spin_lock_irq(host->host_lock);
 873
 874         /* Finish all still pending commands. */
 875         scsifront_finish_all(info);
 876
 877         spin_unlock_irq(host->host_lock);
 878
 879         /* Reconnect to dom0. */
 880         scsifront_free_ring(info);
 881         err = scsifront_init_ring(info);
 882         if (err) {
 883                 dev_err(&dev->dev, "fail to resume %d\n", err);
 884                 scsi_host_put(host);
 885                 return err;
 886         }
 887
 888         xenbus_switch_state(dev, XenbusStateInitialised);
 889
 890         return 0;
 891 }
 892
 893 static int scsifront_suspend(struct xenbus_device *dev)
 894 {
 895         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 896         struct Scsi_Host *host = info->host;
 897         int err = 0;
 898
 899         /* No new commands for the backend. */
 900         spin_lock_irq(host->host_lock);
 901         info->pause = 1;
 902         while (info->callers && !err) {
 903                 info->waiting_pause = 1;
 904                 info->wait_ring_available = 0;
 905                 spin_unlock_irq(host->host_lock);
 906                 wake_up(&info->wq_sync);
 907                 err = wait_event_interruptible(info->wq_pause,
 908                                                !info->waiting_pause);
 909                 spin_lock_irq(host->host_lock);
 910         }
 911         spin_unlock_irq(host->host_lock);
 912         return err;
 913 }
 914
 915 static int scsifront_remove(struct xenbus_device *dev)
 916 {
 917         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 918
 919         pr_debug("%s: %s removed\n", __func__, dev->nodename);
 920
 921         mutex_lock(&scsifront_mutex);
 922         if (info->host_active) {
 923                 /* Scsi_host not yet removed */
 924                 scsi_remove_host(info->host);
 925                 info->host_active = 0;
 926         }
 927         mutex_unlock(&scsifront_mutex);
 928
 929         scsifront_free_ring(info);
 930         scsi_host_put(info->host);
 931
 932         return 0;
 933 }
 934
 935 static void scsifront_disconnect(struct vscsifrnt_info *info)
 936 {
 937         struct xenbus_device *dev = info->dev;
 938         struct Scsi_Host *host = info->host;
 939
 940         pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
 941
 942         /*
 943          * When this function is executed, all devices of
 944          * Frontend have been deleted.
 945          * Therefore, it need not block I/O before remove_host.
 946          */
 947
 948         mutex_lock(&scsifront_mutex);
 949         if (info->host_active) {
 950                 scsi_remove_host(host);
 951                 info->host_active = 0;
 952         }
 953         mutex_unlock(&scsifront_mutex);
 954
 955         xenbus_frontend_closed(dev);
 956 }
 957
 958 static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
 959 {
 960         struct xenbus_device *dev = info->dev;
 961         int i, err = 0;
 962         char str[64];
 963         char **dir;
 964         unsigned int dir_n = 0;
 965         unsigned int device_state;
 966         unsigned int hst, chn, tgt, lun;
 967         struct scsi_device *sdev;
 968
 969         dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
 970         if (IS_ERR(dir))
 971                 return;
 972
 973         /* mark current task as the one allowed to modify device states */
 974         BUG_ON(info->curr);
 975         info->curr = current;
 976
 977         for (i = 0; i < dir_n; i++) {
 978                 /* read status */
 979                 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
 980                 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
 981                                    &device_state);
 982                 if (XENBUS_EXIST_ERR(err))
 983                         continue;
 984
 985                 /* virtual SCSI device */
 986                 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
 987                 err = xenbus_scanf(XBT_NIL, dev->otherend, str,
 988                                    "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
 989                 if (XENBUS_EXIST_ERR(err))
 990                         continue;
 991
 992                 /*
 993                  * Front device state path, used in slave_configure called
 994                  * on successfull scsi_add_device, and in slave_destroy called
 995                  * on remove of a device.
 996                  */
 997                 snprintf(info->dev_state_path, sizeof(info->dev_state_path),
 998                          "vscsi-devs/%s/state", dir[i]);
 999
1000                 switch (op) {
1001                 case VSCSIFRONT_OP_ADD_LUN:
1002                         if (device_state != XenbusStateInitialised)
1003                                 break;
1004
1005                         if (scsi_add_device(info->host, chn, tgt, lun)) {
1006                                 dev_err(&dev->dev, "scsi_add_device\n");
1007                                 xenbus_printf(XBT_NIL, dev->nodename,
1008                                               info->dev_state_path,
1009                                               "%d", XenbusStateClosed);
1010                         }
1011                         break;
1012                 case VSCSIFRONT_OP_DEL_LUN:
1013                         if (device_state != XenbusStateClosing)
1014                                 break;
1015
1016                         sdev = scsi_device_lookup(info->host, chn, tgt, lun);
1017                         if (sdev) {
1018                                 scsi_remove_device(sdev);
1019                                 scsi_device_put(sdev);
1020                         }
1021                         break;
1022                 case VSCSIFRONT_OP_READD_LUN:
1023                         if (device_state == XenbusStateConnected)
1024                                 xenbus_printf(XBT_NIL, dev->nodename,
1025                                               info->dev_state_path,
1026                                               "%d", XenbusStateConnected);
1027                         break;
1028                 default:
1029                         break;
1030                 }
1031         }
1032
1033         info->curr = NULL;
1034
1035         kfree(dir);
1036 }
1037
1038 static void scsifront_read_backend_params(struct xenbus_device *dev,
1039                                           struct vscsifrnt_info *info)
1040 {
1041         unsigned int sg_grant, nr_segs;
1042         struct Scsi_Host *host = info->host;
1043
1044         sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0);
1045         nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
1046         nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
1047         nr_segs = min_t(unsigned int, nr_segs,
1048                         VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
1049                         sizeof(struct scsiif_request_segment));
1050
1051         if (!info->pause && sg_grant)
1052                 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);
1053         else if (info->pause && nr_segs < host->sg_tablesize)
1054                 dev_warn(&dev->dev,
1055                          "SG entries decreased from %d to %u - device may not work properly anymore\n",
1056                          host->sg_tablesize, nr_segs);
1057
1058         host->sg_tablesize = nr_segs;
1059         host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;
1060 }
1061
1062 static void scsifront_backend_changed(struct xenbus_device *dev,
1063                                       enum xenbus_state backend_state)
1064 {
1065         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1066
1067         pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
1068
1069         switch (backend_state) {
1070         case XenbusStateUnknown:
1071         case XenbusStateInitialising:
1072         case XenbusStateInitWait:
1073         case XenbusStateInitialised:
1074                 break;
1075
1076         case XenbusStateConnected:
1077                 scsifront_read_backend_params(dev, info);
1078
1079                 if (info->pause) {
1080                         scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);
1081                         xenbus_switch_state(dev, XenbusStateConnected);
1082                         info->pause = 0;
1083                         return;
1084                 }
1085
1086                 if (xenbus_read_driver_state(dev->nodename) ==
1087                     XenbusStateInitialised)
1088                         scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1089
1090                 if (dev->state != XenbusStateConnected)
1091                         xenbus_switch_state(dev, XenbusStateConnected);
1092                 break;
1093
1094         case XenbusStateClosed:
1095                 if (dev->state == XenbusStateClosed)
1096                         break;
1097                 /* Missed the backend's Closing state -- fallthrough */
1098         case XenbusStateClosing:
1099                 scsifront_disconnect(info);
1100                 break;
1101
1102         case XenbusStateReconfiguring:
1103                 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
1104                 xenbus_switch_state(dev, XenbusStateReconfiguring);
1105                 break;
1106
1107         case XenbusStateReconfigured:
1108                 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1109                 xenbus_switch_state(dev, XenbusStateConnected);
1110                 break;
1111         }
1112 }
1113
1114 static const struct xenbus_device_id scsifront_ids[] = {
1115         { "vscsi" },
1116         { "" }
1117 };
1118
1119 static struct xenbus_driver scsifront_driver = {
1120         .ids                    = scsifront_ids,
1121         .probe                  = scsifront_probe,
1122         .remove                 = scsifront_remove,
1123         .resume                 = scsifront_resume,
1124         .suspend                = scsifront_suspend,
1125         .otherend_changed       = scsifront_backend_changed,
1126 };
1127
1128 static int __init scsifront_init(void)
1129 {
1130         if (!xen_domain())
1131                 return -ENODEV;
1132
1133         return xenbus_register_frontend(&scsifront_driver);
1134 }
1135 module_init(scsifront_init);
1136
1137 static void __exit scsifront_exit(void)
1138 {
1139         xenbus_unregister_driver(&scsifront_driver);
1140 }
1141 module_exit(scsifront_exit);
1142
1143 MODULE_DESCRIPTION("Xen SCSI frontend driver");
1144 MODULE_LICENSE("GPL");
1145 MODULE_ALIAS("xen:vscsi");
1146 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");