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
 538         shadow->sc  = sc;
 539         shadow->act = VSCSIIF_ACT_SCSI_CDB;
 540
 541         spin_lock_irqsave(shost->host_lock, flags);
 542         if (scsifront_enter(info)) {
 543                 spin_unlock_irqrestore(shost->host_lock, flags);
 544                 return SCSI_MLQUEUE_HOST_BUSY;
 545         }
 546
 547         err = map_data_for_request(info, sc, shadow);
 548         if (err < 0) {
 549                 pr_debug("%s: err %d\n", __func__, err);
 550                 scsifront_return(info);
 551                 spin_unlock_irqrestore(shost->host_lock, flags);
 552                 if (err == -ENOMEM)
 553                         return SCSI_MLQUEUE_HOST_BUSY;
 554                 sc->result = DID_ERROR << 16;
 555                 sc->scsi_done(sc);
 556                 return 0;
 557         }
 558
 559         if (scsifront_do_request(info, shadow)) {
 560                 scsifront_gnttab_done(info, shadow);
 561                 goto busy;
 562         }
 563
 564         scsifront_return(info);
 565         spin_unlock_irqrestore(shost->host_lock, flags);
 566
 567         return 0;
 568
 569 busy:
 570         scsifront_return(info);
 571         spin_unlock_irqrestore(shost->host_lock, flags);
 572         pr_debug("%s: busy\n", __func__);
 573         return SCSI_MLQUEUE_HOST_BUSY;
 574 }
 575
 576 /*
 577  * Any exception handling (reset or abort) must be forwarded to the backend.
 578  * We have to wait until an answer is returned. This answer contains the
 579  * result to be returned to the requestor.
 580  */
 581 static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)
 582 {
 583         struct Scsi_Host *host = sc->device->host;
 584         struct vscsifrnt_info *info = shost_priv(host);
 585         struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
 586         int err = 0;
 587
 588         shadow = kzalloc(sizeof(*shadow), GFP_NOIO);
 589         if (!shadow)
 590                 return FAILED;
 591
 592         shadow->act = act;
 593         shadow->rslt_reset = RSLT_RESET_WAITING;
 594         shadow->sc = sc;
 595         shadow->ref_rqid = s->rqid;
 596         init_waitqueue_head(&shadow->wq_reset);
 597
 598         spin_lock_irq(host->host_lock);
 599
 600         for (;;) {
 601                 if (scsifront_enter(info))
 602                         goto fail;
 603
 604                 if (!scsifront_do_request(info, shadow))
 605                         break;
 606
 607                 scsifront_return(info);
 608                 if (err)
 609                         goto fail;
 610                 info->wait_ring_available = 1;
 611                 spin_unlock_irq(host->host_lock);
 612                 err = wait_event_interruptible(info->wq_sync,
 613                                                !info->wait_ring_available);
 614                 spin_lock_irq(host->host_lock);
 615         }
 616
 617         spin_unlock_irq(host->host_lock);
 618         err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
 619         spin_lock_irq(host->host_lock);
 620
 621         if (!err) {
 622                 err = shadow->rslt_reset;
 623                 scsifront_put_rqid(info, shadow->rqid);
 624                 kfree(shadow);
 625         } else {
 626                 spin_lock(&info->shadow_lock);
 627                 shadow->rslt_reset = RSLT_RESET_ERR;
 628                 spin_unlock(&info->shadow_lock);
 629                 err = FAILED;
 630         }
 631
 632         scsifront_return(info);
 633         spin_unlock_irq(host->host_lock);
 634         return err;
 635
 636 fail:
 637         spin_unlock_irq(host->host_lock);
 638         kfree(shadow);
 639         return FAILED;
 640 }
 641
 642 static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
 643 {
 644         pr_debug("%s\n", __func__);
 645         return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);
 646 }
 647
 648 static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
 649 {
 650         pr_debug("%s\n", __func__);
 651         return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);
 652 }
 653
 654 static int scsifront_sdev_configure(struct scsi_device *sdev)
 655 {
 656         struct vscsifrnt_info *info = shost_priv(sdev->host);
 657         int err;
 658
 659         if (info && current == info->curr) {
 660                 err = xenbus_printf(XBT_NIL, info->dev->nodename,
 661                               info->dev_state_path, "%d", XenbusStateConnected);
 662                 if (err) {
 663                         xenbus_dev_error(info->dev, err,
 664                                 "%s: writing dev_state_path", __func__);
 665                         return err;
 666                 }
 667         }
 668
 669         return 0;
 670 }
 671
 672 static void scsifront_sdev_destroy(struct scsi_device *sdev)
 673 {
 674         struct vscsifrnt_info *info = shost_priv(sdev->host);
 675         int err;
 676
 677         if (info && current == info->curr) {
 678                 err = xenbus_printf(XBT_NIL, info->dev->nodename,
 679                               info->dev_state_path, "%d", XenbusStateClosed);
 680                 if (err)
 681                         xenbus_dev_error(info->dev, err,
 682                                 "%s: writing dev_state_path", __func__);
 683         }
 684 }
 685
 686 static struct scsi_host_template scsifront_sht = {
 687         .module                 = THIS_MODULE,
 688         .name                   = "Xen SCSI frontend driver",
 689         .queuecommand           = scsifront_queuecommand,
 690         .eh_abort_handler       = scsifront_eh_abort_handler,
 691         .eh_device_reset_handler = scsifront_dev_reset_handler,
 692         .slave_configure        = scsifront_sdev_configure,
 693         .slave_destroy          = scsifront_sdev_destroy,
 694         .cmd_per_lun            = VSCSIIF_DEFAULT_CMD_PER_LUN,
 695         .can_queue              = VSCSIIF_MAX_REQS,
 696         .this_id                = -1,
 697         .cmd_size               = sizeof(struct vscsifrnt_shadow),
 698         .sg_tablesize           = VSCSIIF_SG_TABLESIZE,
 699         .use_clustering         = DISABLE_CLUSTERING,
 700         .proc_name              = "scsifront",
 701 };
 702
 703 static int scsifront_alloc_ring(struct vscsifrnt_info *info)
 704 {
 705         struct xenbus_device *dev = info->dev;
 706         struct vscsiif_sring *sring;
 707         grant_ref_t gref;
 708         int err = -ENOMEM;
 709
 710         /***** Frontend to Backend ring start *****/
 711         sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL);
 712         if (!sring) {
 713                 xenbus_dev_fatal(dev, err,
 714                         "fail to allocate shared ring (Front to Back)");
 715                 return err;
 716         }
 717         SHARED_RING_INIT(sring);
 718         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 719
 720         err = xenbus_grant_ring(dev, sring, 1, &gref);
 721         if (err < 0) {
 722                 free_page((unsigned long)sring);
 723                 xenbus_dev_fatal(dev, err,
 724                         "fail to grant shared ring (Front to Back)");
 725                 return err;
 726         }
 727         info->ring_ref = gref;
 728
 729         err = xenbus_alloc_evtchn(dev, &info->evtchn);
 730         if (err) {
 731                 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
 732                 goto free_gnttab;
 733         }
 734
 735         err = bind_evtchn_to_irq(info->evtchn);
 736         if (err <= 0) {
 737                 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
 738                 goto free_gnttab;
 739         }
 740
 741         info->irq = err;
 742
 743         err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
 744                                    IRQF_ONESHOT, "scsifront", info);
 745         if (err) {
 746                 xenbus_dev_fatal(dev, err, "request_threaded_irq");
 747                 goto free_irq;
 748         }
 749
 750         return 0;
 751
 752 /* free resource */
 753 free_irq:
 754         unbind_from_irqhandler(info->irq, info);
 755 free_gnttab:
 756         gnttab_end_foreign_access(info->ring_ref, 0,
 757                                   (unsigned long)info->ring.sring);
 758
 759         return err;
 760 }
 761
 762 static void scsifront_free_ring(struct vscsifrnt_info *info)
 763 {
 764         unbind_from_irqhandler(info->irq, info);
 765         gnttab_end_foreign_access(info->ring_ref, 0,
 766                                   (unsigned long)info->ring.sring);
 767 }
 768
 769 static int scsifront_init_ring(struct vscsifrnt_info *info)
 770 {
 771         struct xenbus_device *dev = info->dev;
 772         struct xenbus_transaction xbt;
 773         int err;
 774
 775         pr_debug("%s\n", __func__);
 776
 777         err = scsifront_alloc_ring(info);
 778         if (err)
 779                 return err;
 780         pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
 781
 782 again:
 783         err = xenbus_transaction_start(&xbt);
 784         if (err)
 785                 xenbus_dev_fatal(dev, err, "starting transaction");
 786
 787         err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
 788                             info->ring_ref);
 789         if (err) {
 790                 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
 791                 goto fail;
 792         }
 793
 794         err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
 795                             info->evtchn);
 796
 797         if (err) {
 798                 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
 799                 goto fail;
 800         }
 801
 802         err = xenbus_transaction_end(xbt, 0);
 803         if (err) {
 804                 if (err == -EAGAIN)
 805                         goto again;
 806                 xenbus_dev_fatal(dev, err, "completing transaction");
 807                 goto free_sring;
 808         }
 809
 810         return 0;
 811
 812 fail:
 813         xenbus_transaction_end(xbt, 1);
 814 free_sring:
 815         scsifront_free_ring(info);
 816
 817         return err;
 818 }
 819
 820
 821 static int scsifront_probe(struct xenbus_device *dev,
 822                            const struct xenbus_device_id *id)
 823 {
 824         struct vscsifrnt_info *info;
 825         struct Scsi_Host *host;
 826         int err = -ENOMEM;
 827         char name[TASK_COMM_LEN];
 828
 829         host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
 830         if (!host) {
 831                 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
 832                 return err;
 833         }
 834         info = (struct vscsifrnt_info *)host->hostdata;
 835
 836         dev_set_drvdata(&dev->dev, info);
 837         info->dev = dev;
 838
 839         bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
 840
 841         err = scsifront_init_ring(info);
 842         if (err) {
 843                 scsi_host_put(host);
 844                 return err;
 845         }
 846
 847         init_waitqueue_head(&info->wq_sync);
 848         init_waitqueue_head(&info->wq_pause);
 849         spin_lock_init(&info->shadow_lock);
 850
 851         snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
 852
 853         host->max_id      = VSCSIIF_MAX_TARGET;
 854         host->max_channel = 0;
 855         host->max_lun     = VSCSIIF_MAX_LUN;
 856         host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
 857         host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
 858
 859         err = scsi_add_host(host, &dev->dev);
 860         if (err) {
 861                 dev_err(&dev->dev, "fail to add scsi host %d\n", err);
 862                 goto free_sring;
 863         }
 864         info->host = host;
 865         info->host_active = 1;
 866
 867         xenbus_switch_state(dev, XenbusStateInitialised);
 868
 869         return 0;
 870
 871 free_sring:
 872         scsifront_free_ring(info);
 873         scsi_host_put(host);
 874         return err;
 875 }
 876
 877 static int scsifront_resume(struct xenbus_device *dev)
 878 {
 879         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 880         struct Scsi_Host *host = info->host;
 881         int err;
 882
 883         spin_lock_irq(host->host_lock);
 884
 885         /* Finish all still pending commands. */
 886         scsifront_finish_all(info);
 887
 888         spin_unlock_irq(host->host_lock);
 889
 890         /* Reconnect to dom0. */
 891         scsifront_free_ring(info);
 892         err = scsifront_init_ring(info);
 893         if (err) {
 894                 dev_err(&dev->dev, "fail to resume %d\n", err);
 895                 scsi_host_put(host);
 896                 return err;
 897         }
 898
 899         xenbus_switch_state(dev, XenbusStateInitialised);
 900
 901         return 0;
 902 }
 903
 904 static int scsifront_suspend(struct xenbus_device *dev)
 905 {
 906         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 907         struct Scsi_Host *host = info->host;
 908         int err = 0;
 909
 910         /* No new commands for the backend. */
 911         spin_lock_irq(host->host_lock);
 912         info->pause = 1;
 913         while (info->callers && !err) {
 914                 info->waiting_pause = 1;
 915                 info->wait_ring_available = 0;
 916                 spin_unlock_irq(host->host_lock);
 917                 wake_up(&info->wq_sync);
 918                 err = wait_event_interruptible(info->wq_pause,
 919                                                !info->waiting_pause);
 920                 spin_lock_irq(host->host_lock);
 921         }
 922         spin_unlock_irq(host->host_lock);
 923         return err;
 924 }
 925
 926 static int scsifront_remove(struct xenbus_device *dev)
 927 {
 928         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 929
 930         pr_debug("%s: %s removed\n", __func__, dev->nodename);
 931
 932         mutex_lock(&scsifront_mutex);
 933         if (info->host_active) {
 934                 /* Scsi_host not yet removed */
 935                 scsi_remove_host(info->host);
 936                 info->host_active = 0;
 937         }
 938         mutex_unlock(&scsifront_mutex);
 939
 940         scsifront_free_ring(info);
 941         scsi_host_put(info->host);
 942
 943         return 0;
 944 }
 945
 946 static void scsifront_disconnect(struct vscsifrnt_info *info)
 947 {
 948         struct xenbus_device *dev = info->dev;
 949         struct Scsi_Host *host = info->host;
 950
 951         pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
 952
 953         /*
 954          * When this function is executed, all devices of
 955          * Frontend have been deleted.
 956          * Therefore, it need not block I/O before remove_host.
 957          */
 958
 959         mutex_lock(&scsifront_mutex);
 960         if (info->host_active) {
 961                 scsi_remove_host(host);
 962                 info->host_active = 0;
 963         }
 964         mutex_unlock(&scsifront_mutex);
 965
 966         xenbus_frontend_closed(dev);
 967 }
 968
 969 static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
 970 {
 971         struct xenbus_device *dev = info->dev;
 972         int i, err = 0;
 973         char str[64];
 974         char **dir;
 975         unsigned int dir_n = 0;
 976         unsigned int device_state;
 977         unsigned int hst, chn, tgt, lun;
 978         struct scsi_device *sdev;
 979
 980         dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
 981         if (IS_ERR(dir))
 982                 return;
 983
 984         /* mark current task as the one allowed to modify device states */
 985         BUG_ON(info->curr);
 986         info->curr = current;
 987
 988         for (i = 0; i < dir_n; i++) {
 989                 /* read status */
 990                 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
 991                 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
 992                                    &device_state);
 993                 if (XENBUS_EXIST_ERR(err))
 994                         continue;
 995
 996                 /* virtual SCSI device */
 997                 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
 998                 err = xenbus_scanf(XBT_NIL, dev->otherend, str,
 999                                    "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
1000                 if (XENBUS_EXIST_ERR(err))
1001                         continue;
1002
1003                 /*
1004                  * Front device state path, used in slave_configure called
1005                  * on successfull scsi_add_device, and in slave_destroy called
1006                  * on remove of a device.
1007                  */
1008                 snprintf(info->dev_state_path, sizeof(info->dev_state_path),
1009                          "vscsi-devs/%s/state", dir[i]);
1010
1011                 switch (op) {
1012                 case VSCSIFRONT_OP_ADD_LUN:
1013                         if (device_state != XenbusStateInitialised)
1014                                 break;
1015
1016                         if (scsi_add_device(info->host, chn, tgt, lun)) {
1017                                 dev_err(&dev->dev, "scsi_add_device\n");
1018                                 err = xenbus_printf(XBT_NIL, dev->nodename,
1019                                               info->dev_state_path,
1020                                               "%d", XenbusStateClosed);
1021                                 if (err)
1022                                         xenbus_dev_error(dev, err,
1023                                                 "%s: writing dev_state_path", __func__);
1024                         }
1025                         break;
1026                 case VSCSIFRONT_OP_DEL_LUN:
1027                         if (device_state != XenbusStateClosing)
1028                                 break;
1029
1030                         sdev = scsi_device_lookup(info->host, chn, tgt, lun);
1031                         if (sdev) {
1032                                 scsi_remove_device(sdev);
1033                                 scsi_device_put(sdev);
1034                         }
1035                         break;
1036                 case VSCSIFRONT_OP_READD_LUN:
1037                         if (device_state == XenbusStateConnected) {
1038                                 err = xenbus_printf(XBT_NIL, dev->nodename,
1039                                               info->dev_state_path,
1040                                               "%d", XenbusStateConnected);
1041                                 if (err)
1042                                         xenbus_dev_error(dev, err,
1043                                                 "%s: writing dev_state_path", __func__);
1044                         }
1045                         break;
1046                 default:
1047                         break;
1048                 }
1049         }
1050
1051         info->curr = NULL;
1052
1053         kfree(dir);
1054 }
1055
1056 static void scsifront_read_backend_params(struct xenbus_device *dev,
1057                                           struct vscsifrnt_info *info)
1058 {
1059         unsigned int sg_grant, nr_segs;
1060         struct Scsi_Host *host = info->host;
1061
1062         sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0);
1063         nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
1064         nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
1065         nr_segs = min_t(unsigned int, nr_segs,
1066                         VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
1067                         sizeof(struct scsiif_request_segment));
1068
1069         if (!info->pause && sg_grant)
1070                 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);
1071         else if (info->pause && nr_segs < host->sg_tablesize)
1072                 dev_warn(&dev->dev,
1073                          "SG entries decreased from %d to %u - device may not work properly anymore\n",
1074                          host->sg_tablesize, nr_segs);
1075
1076         host->sg_tablesize = nr_segs;
1077         host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;
1078 }
1079
1080 static void scsifront_backend_changed(struct xenbus_device *dev,
1081                                       enum xenbus_state backend_state)
1082 {
1083         struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1084
1085         pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
1086
1087         switch (backend_state) {
1088         case XenbusStateUnknown:
1089         case XenbusStateInitialising:
1090         case XenbusStateInitWait:
1091         case XenbusStateInitialised:
1092                 break;
1093
1094         case XenbusStateConnected:
1095                 scsifront_read_backend_params(dev, info);
1096
1097                 if (info->pause) {
1098                         scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);
1099                         xenbus_switch_state(dev, XenbusStateConnected);
1100                         info->pause = 0;
1101                         return;
1102                 }
1103
1104                 if (xenbus_read_driver_state(dev->nodename) ==
1105                     XenbusStateInitialised)
1106                         scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1107
1108                 if (dev->state != XenbusStateConnected)
1109                         xenbus_switch_state(dev, XenbusStateConnected);
1110                 break;
1111
1112         case XenbusStateClosed:
1113                 if (dev->state == XenbusStateClosed)
1114                         break;
1115                 /* Missed the backend's Closing state -- fallthrough */
1116         case XenbusStateClosing:
1117                 scsifront_disconnect(info);
1118                 break;
1119
1120         case XenbusStateReconfiguring:
1121                 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
1122                 xenbus_switch_state(dev, XenbusStateReconfiguring);
1123                 break;
1124
1125         case XenbusStateReconfigured:
1126                 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1127                 xenbus_switch_state(dev, XenbusStateConnected);
1128                 break;
1129         }
1130 }
1131
1132 static const struct xenbus_device_id scsifront_ids[] = {
1133         { "vscsi" },
1134         { "" }
1135 };
1136
1137 static struct xenbus_driver scsifront_driver = {
1138         .ids                    = scsifront_ids,
1139         .probe                  = scsifront_probe,
1140         .remove                 = scsifront_remove,
1141         .resume                 = scsifront_resume,
1142         .suspend                = scsifront_suspend,
1143         .otherend_changed       = scsifront_backend_changed,
1144 };
1145
1146 static int __init scsifront_init(void)
1147 {
1148         if (!xen_domain())
1149                 return -ENODEV;
1150
1151         return xenbus_register_frontend(&scsifront_driver);
1152 }
1153 module_init(scsifront_init);
1154
1155 static void __exit scsifront_exit(void)
1156 {
1157         xenbus_unregister_driver(&scsifront_driver);
1158 }
1159 module_exit(scsifront_exit);
1160
1161 MODULE_DESCRIPTION("Xen SCSI frontend driver");
1162 MODULE_LICENSE("GPL");
1163 MODULE_ALIAS("xen:vscsi");
1164 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");