drivers/xen/xen-scsiback.c

   1 /*
   2  * Xen SCSI backend driver
   3  *
   4  * Copyright (c) 2008, FUJITSU Limited
   5  *
   6  * Based on the blkback driver code.
   7  * Adaption to kernel taget core infrastructure taken from vhost/scsi.c
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License version 2
  11  * as published by the Free Software Foundation; or, when distributed
  12  * separately from the Linux kernel or incorporated into other
  13  * software packages, subject to the following license:
  14  *
  15  * Permission is hereby granted, free of charge, to any person obtaining a copy
  16  * of this source file (the "Software"), to deal in the Software without
  17  * restriction, including without limitation the rights to use, copy, modify,
  18  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  19  * and to permit persons to whom the Software is furnished to do so, subject to
  20  * the following conditions:
  21  *
  22  * The above copyright notice and this permission notice shall be included in
  23  * all copies or substantial portions of the Software.
  24  *
  25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  26  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  27  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  28  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  29  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  30  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  31  * IN THE SOFTWARE.
  32  */
  33
  34 #define pr_fmt(fmt) "xen-pvscsi: " fmt
  35
  36 #include <stdarg.h>
  37
  38 #include <linux/module.h>
  39 #include <linux/utsname.h>
  40 #include <linux/interrupt.h>
  41 #include <linux/slab.h>
  42 #include <linux/wait.h>
  43 #include <linux/sched.h>
  44 #include <linux/list.h>
  45 #include <linux/gfp.h>
  46 #include <linux/delay.h>
  47 #include <linux/spinlock.h>
  48 #include <linux/configfs.h>
  49
  50 #include <generated/utsrelease.h>
  51
  52 #include <scsi/scsi_host.h> /* SG_ALL */
  53
  54 #include <target/target_core_base.h>
  55 #include <target/target_core_fabric.h>
  56
  57 #include <asm/hypervisor.h>
  58
  59 #include <xen/xen.h>
  60 #include <xen/balloon.h>
  61 #include <xen/events.h>
  62 #include <xen/xenbus.h>
  63 #include <xen/grant_table.h>
  64 #include <xen/page.h>
  65
  66 #include <xen/interface/grant_table.h>
  67 #include <xen/interface/io/vscsiif.h>
  68
  69 #define VSCSI_VERSION   "v0.1"
  70 #define VSCSI_NAMELEN   32
  71
  72 struct ids_tuple {
  73         unsigned int hst;               /* host    */
  74         unsigned int chn;               /* channel */
  75         unsigned int tgt;               /* target  */
  76         unsigned int lun;               /* LUN     */
  77 };
  78
  79 struct v2p_entry {
  80         struct ids_tuple v;             /* translate from */
  81         struct scsiback_tpg *tpg;       /* translate to   */
  82         unsigned int lun;
  83         struct kref kref;
  84         struct list_head l;
  85 };
  86
  87 struct vscsibk_info {
  88         struct xenbus_device *dev;
  89
  90         domid_t domid;
  91         unsigned int irq;
  92
  93         struct vscsiif_back_ring ring;
  94
  95         spinlock_t ring_lock;
  96         atomic_t nr_unreplied_reqs;
  97
  98         spinlock_t v2p_lock;
  99         struct list_head v2p_entry_lists;
 100
 101         wait_queue_head_t waiting_to_free;
 102 };
 103
 104 /* theoretical maximum of grants for one request */
 105 #define VSCSI_MAX_GRANTS        (SG_ALL + VSCSIIF_SG_TABLESIZE)
 106
 107 /*
 108  * VSCSI_GRANT_BATCH is the maximum number of grants to be processed in one
 109  * call to map/unmap grants. Don't choose it too large, as there are arrays
 110  * with VSCSI_GRANT_BATCH elements allocated on the stack.
 111  */
 112 #define VSCSI_GRANT_BATCH       16
 113
 114 struct vscsibk_pend {
 115         uint16_t rqid;
 116
 117         uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE];
 118         uint8_t cmd_len;
 119
 120         uint8_t sc_data_direction;
 121         uint16_t n_sg;          /* real length of SG list */
 122         uint16_t n_grants;      /* SG pages and potentially SG list */
 123         uint32_t data_len;
 124         uint32_t result;
 125
 126         struct vscsibk_info *info;
 127         struct v2p_entry *v2p;
 128         struct scatterlist *sgl;
 129
 130         uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE];
 131
 132         grant_handle_t grant_handles[VSCSI_MAX_GRANTS];
 133         struct page *pages[VSCSI_MAX_GRANTS];
 134
 135         struct se_cmd se_cmd;
 136
 137         atomic_t tmr_complete;
 138         wait_queue_head_t tmr_wait;
 139 };
 140
 141 #define VSCSI_DEFAULT_SESSION_TAGS      128
 142
 143 struct scsiback_nexus {
 144         /* Pointer to TCM session for I_T Nexus */
 145         struct se_session *tvn_se_sess;
 146 };
 147
 148 struct scsiback_tport {
 149         /* SCSI protocol the tport is providing */
 150         u8 tport_proto_id;
 151         /* Binary World Wide unique Port Name for pvscsi Target port */
 152         u64 tport_wwpn;
 153         /* ASCII formatted WWPN for pvscsi Target port */
 154         char tport_name[VSCSI_NAMELEN];
 155         /* Returned by scsiback_make_tport() */
 156         struct se_wwn tport_wwn;
 157 };
 158
 159 struct scsiback_tpg {
 160         /* scsiback port target portal group tag for TCM */
 161         u16 tport_tpgt;
 162         /* track number of TPG Port/Lun Links wrt explicit I_T Nexus shutdown */
 163         int tv_tpg_port_count;
 164         /* xen-pvscsi references to tpg_nexus, protected by tv_tpg_mutex */
 165         int tv_tpg_fe_count;
 166         /* list for scsiback_list */
 167         struct list_head tv_tpg_list;
 168         /* Used to protect access for tpg_nexus */
 169         struct mutex tv_tpg_mutex;
 170         /* Pointer to the TCM pvscsi I_T Nexus for this TPG endpoint */
 171         struct scsiback_nexus *tpg_nexus;
 172         /* Pointer back to scsiback_tport */
 173         struct scsiback_tport *tport;
 174         /* Returned by scsiback_make_tpg() */
 175         struct se_portal_group se_tpg;
 176         /* alias used in xenstore */
 177         char param_alias[VSCSI_NAMELEN];
 178         /* list of info structures related to this target portal group */
 179         struct list_head info_list;
 180 };
 181
 182 #define SCSIBACK_INVALID_HANDLE (~0)
 183
 184 static bool log_print_stat;
 185 module_param(log_print_stat, bool, 0644);
 186
 187 static int scsiback_max_buffer_pages = 1024;
 188 module_param_named(max_buffer_pages, scsiback_max_buffer_pages, int, 0644);
 189 MODULE_PARM_DESC(max_buffer_pages,
 190 "Maximum number of free pages to keep in backend buffer");
 191
 192 static DEFINE_SPINLOCK(free_pages_lock);
 193 static int free_pages_num;
 194 static LIST_HEAD(scsiback_free_pages);
 195
 196 /* Global spinlock to protect scsiback TPG list */
 197 static DEFINE_MUTEX(scsiback_mutex);
 198 static LIST_HEAD(scsiback_list);
 199
 200 static void scsiback_get(struct vscsibk_info *info)
 201 {
 202         atomic_inc(&info->nr_unreplied_reqs);
 203 }
 204
 205 static void scsiback_put(struct vscsibk_info *info)
 206 {
 207         if (atomic_dec_and_test(&info->nr_unreplied_reqs))
 208                 wake_up(&info->waiting_to_free);
 209 }
 210
 211 static void put_free_pages(struct page **page, int num)
 212 {
 213         unsigned long flags;
 214         int i = free_pages_num + num, n = num;
 215
 216         if (num == 0)
 217                 return;
 218         if (i > scsiback_max_buffer_pages) {
 219                 n = min(num, i - scsiback_max_buffer_pages);
 220                 gnttab_free_pages(n, page + num - n);
 221                 n = num - n;
 222         }
 223         spin_lock_irqsave(&free_pages_lock, flags);
 224         for (i = 0; i < n; i++)
 225                 list_add(&page[i]->lru, &scsiback_free_pages);
 226         free_pages_num += n;
 227         spin_unlock_irqrestore(&free_pages_lock, flags);
 228 }
 229
 230 static int get_free_page(struct page **page)
 231 {
 232         unsigned long flags;
 233
 234         spin_lock_irqsave(&free_pages_lock, flags);
 235         if (list_empty(&scsiback_free_pages)) {
 236                 spin_unlock_irqrestore(&free_pages_lock, flags);
 237                 return gnttab_alloc_pages(1, page);
 238         }
 239         page[0] = list_first_entry(&scsiback_free_pages, struct page, lru);
 240         list_del(&page[0]->lru);
 241         free_pages_num--;
 242         spin_unlock_irqrestore(&free_pages_lock, flags);
 243         return 0;
 244 }
 245
 246 static unsigned long vaddr_page(struct page *page)
 247 {
 248         unsigned long pfn = page_to_pfn(page);
 249
 250         return (unsigned long)pfn_to_kaddr(pfn);
 251 }
 252
 253 static unsigned long vaddr(struct vscsibk_pend *req, int seg)
 254 {
 255         return vaddr_page(req->pages[seg]);
 256 }
 257
 258 static void scsiback_print_status(char *sense_buffer, int errors,
 259                                         struct vscsibk_pend *pending_req)
 260 {
 261         struct scsiback_tpg *tpg = pending_req->v2p->tpg;
 262
 263         pr_err("[%s:%d] cmnd[0]=%02x -> st=%02x msg=%02x host=%02x drv=%02x\n",
 264                tpg->tport->tport_name, pending_req->v2p->lun,
 265                pending_req->cmnd[0], status_byte(errors), msg_byte(errors),
 266                host_byte(errors), driver_byte(errors));
 267 }
 268
 269 static void scsiback_fast_flush_area(struct vscsibk_pend *req)
 270 {
 271         struct gnttab_unmap_grant_ref unmap[VSCSI_GRANT_BATCH];
 272         struct page *pages[VSCSI_GRANT_BATCH];
 273         unsigned int i, invcount = 0;
 274         grant_handle_t handle;
 275         int err;
 276
 277         kfree(req->sgl);
 278         req->sgl = NULL;
 279         req->n_sg = 0;
 280
 281         if (!req->n_grants)
 282                 return;
 283
 284         for (i = 0; i < req->n_grants; i++) {
 285                 handle = req->grant_handles[i];
 286                 if (handle == SCSIBACK_INVALID_HANDLE)
 287                         continue;
 288                 gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
 289                                     GNTMAP_host_map, handle);
 290                 req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
 291                 pages[invcount] = req->pages[i];
 292                 put_page(pages[invcount]);
 293                 invcount++;
 294                 if (invcount < VSCSI_GRANT_BATCH)
 295                         continue;
 296                 err = gnttab_unmap_refs(unmap, NULL, pages, invcount);
 297                 BUG_ON(err);
 298                 invcount = 0;
 299         }
 300
 301         if (invcount) {
 302                 err = gnttab_unmap_refs(unmap, NULL, pages, invcount);
 303                 BUG_ON(err);
 304         }
 305
 306         put_free_pages(req->pages, req->n_grants);
 307         req->n_grants = 0;
 308 }
 309
 310 static void scsiback_free_translation_entry(struct kref *kref)
 311 {
 312         struct v2p_entry *entry = container_of(kref, struct v2p_entry, kref);
 313         struct scsiback_tpg *tpg = entry->tpg;
 314
 315         mutex_lock(&tpg->tv_tpg_mutex);
 316         tpg->tv_tpg_fe_count--;
 317         mutex_unlock(&tpg->tv_tpg_mutex);
 318
 319         kfree(entry);
 320 }
 321
 322 static void scsiback_send_response(struct vscsibk_info *info,
 323                         char *sense_buffer, int32_t result, uint32_t resid,
 324                         uint16_t rqid)
 325 {
 326         struct vscsiif_response *ring_res;
 327         int notify;
 328         struct scsi_sense_hdr sshdr;
 329         unsigned long flags;
 330         unsigned len;
 331
 332         spin_lock_irqsave(&info->ring_lock, flags);
 333
 334         ring_res = RING_GET_RESPONSE(&info->ring, info->ring.rsp_prod_pvt);
 335         info->ring.rsp_prod_pvt++;
 336
 337         ring_res->rslt   = result;
 338         ring_res->rqid   = rqid;
 339
 340         if (sense_buffer != NULL &&
 341             scsi_normalize_sense(sense_buffer, VSCSIIF_SENSE_BUFFERSIZE,
 342                                  &sshdr)) {
 343                 len = min_t(unsigned, 8 + sense_buffer[7],
 344                             VSCSIIF_SENSE_BUFFERSIZE);
 345                 memcpy(ring_res->sense_buffer, sense_buffer, len);
 346                 ring_res->sense_len = len;
 347         } else {
 348                 ring_res->sense_len = 0;
 349         }
 350
 351         ring_res->residual_len = resid;
 352
 353         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&info->ring, notify);
 354         spin_unlock_irqrestore(&info->ring_lock, flags);
 355
 356         if (notify)
 357                 notify_remote_via_irq(info->irq);
 358 }
 359
 360 static void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result,
 361                         uint32_t resid, struct vscsibk_pend *pending_req)
 362 {
 363         scsiback_send_response(pending_req->info, sense_buffer, result,
 364                                resid, pending_req->rqid);
 365
 366         if (pending_req->v2p)
 367                 kref_put(&pending_req->v2p->kref,
 368                          scsiback_free_translation_entry);
 369 }
 370
 371 static void scsiback_cmd_done(struct vscsibk_pend *pending_req)
 372 {
 373         struct vscsibk_info *info = pending_req->info;
 374         unsigned char *sense_buffer;
 375         unsigned int resid;
 376         int errors;
 377
 378         sense_buffer = pending_req->sense_buffer;
 379         resid        = pending_req->se_cmd.residual_count;
 380         errors       = pending_req->result;
 381
 382         if (errors && log_print_stat)
 383                 scsiback_print_status(sense_buffer, errors, pending_req);
 384
 385         scsiback_fast_flush_area(pending_req);
 386         scsiback_do_resp_with_sense(sense_buffer, errors, resid, pending_req);
 387         scsiback_put(info);
 388         /*
 389          * Drop the extra KREF_ACK reference taken by target_submit_cmd_map_sgls()
 390          * ahead of scsiback_check_stop_free() ->  transport_generic_free_cmd()
 391          * final se_cmd->cmd_kref put.
 392          */
 393         target_put_sess_cmd(&pending_req->se_cmd);
 394 }
 395
 396 static void scsiback_cmd_exec(struct vscsibk_pend *pending_req)
 397 {
 398         struct se_cmd *se_cmd = &pending_req->se_cmd;
 399         struct se_session *sess = pending_req->v2p->tpg->tpg_nexus->tvn_se_sess;
 400         int rc;
 401
 402         scsiback_get(pending_req->info);
 403         se_cmd->tag = pending_req->rqid;
 404         rc = target_submit_cmd_map_sgls(se_cmd, sess, pending_req->cmnd,
 405                         pending_req->sense_buffer, pending_req->v2p->lun,
 406                         pending_req->data_len, 0,
 407                         pending_req->sc_data_direction, TARGET_SCF_ACK_KREF,
 408                         pending_req->sgl, pending_req->n_sg,
 409                         NULL, 0, NULL, 0);
 410         if (rc < 0) {
 411                 transport_send_check_condition_and_sense(se_cmd,
 412                                 TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
 413                 transport_generic_free_cmd(se_cmd, 0);
 414         }
 415 }
 416
 417 static int scsiback_gnttab_data_map_batch(struct gnttab_map_grant_ref *map,
 418         struct page **pg, grant_handle_t *grant, int cnt)
 419 {
 420         int err, i;
 421
 422         if (!cnt)
 423                 return 0;
 424
 425         err = gnttab_map_refs(map, NULL, pg, cnt);
 426         for (i = 0; i < cnt; i++) {
 427                 if (unlikely(map[i].status != GNTST_okay)) {
 428                         pr_err("invalid buffer -- could not remap it\n");
 429                         map[i].handle = SCSIBACK_INVALID_HANDLE;
 430                         if (!err)
 431                                 err = -ENOMEM;
 432                 } else {
 433                         get_page(pg[i]);
 434                 }
 435                 grant[i] = map[i].handle;
 436         }
 437         return err;
 438 }
 439
 440 static int scsiback_gnttab_data_map_list(struct vscsibk_pend *pending_req,
 441                         struct scsiif_request_segment *seg, struct page **pg,
 442                         grant_handle_t *grant, int cnt, u32 flags)
 443 {
 444         int mapcount = 0, i, err = 0;
 445         struct gnttab_map_grant_ref map[VSCSI_GRANT_BATCH];
 446         struct vscsibk_info *info = pending_req->info;
 447
 448         for (i = 0; i < cnt; i++) {
 449                 if (get_free_page(pg + mapcount)) {
 450                         put_free_pages(pg, mapcount);
 451                         pr_err("no grant page\n");
 452                         return -ENOMEM;
 453                 }
 454                 gnttab_set_map_op(&map[mapcount], vaddr_page(pg[mapcount]),
 455                                   flags, seg[i].gref, info->domid);
 456                 mapcount++;
 457                 if (mapcount < VSCSI_GRANT_BATCH)
 458                         continue;
 459                 err = scsiback_gnttab_data_map_batch(map, pg, grant, mapcount);
 460                 pg += mapcount;
 461                 grant += mapcount;
 462                 pending_req->n_grants += mapcount;
 463                 if (err)
 464                         return err;
 465                 mapcount = 0;
 466         }
 467         err = scsiback_gnttab_data_map_batch(map, pg, grant, mapcount);
 468         pending_req->n_grants += mapcount;
 469         return err;
 470 }
 471
 472 static int scsiback_gnttab_data_map(struct vscsiif_request *ring_req,
 473                                         struct vscsibk_pend *pending_req)
 474 {
 475         u32 flags;
 476         int i, err, n_segs, i_seg = 0;
 477         struct page **pg;
 478         struct scsiif_request_segment *seg;
 479         unsigned long end_seg = 0;
 480         unsigned int nr_segments = (unsigned int)ring_req->nr_segments;
 481         unsigned int nr_sgl = 0;
 482         struct scatterlist *sg;
 483         grant_handle_t *grant;
 484
 485         pending_req->n_sg = 0;
 486         pending_req->n_grants = 0;
 487         pending_req->data_len = 0;
 488
 489         nr_segments &= ~VSCSIIF_SG_GRANT;
 490         if (!nr_segments)
 491                 return 0;
 492
 493         if (nr_segments > VSCSIIF_SG_TABLESIZE) {
 494                 pr_debug("invalid parameter nr_seg = %d\n",
 495                         ring_req->nr_segments);
 496                 return -EINVAL;
 497         }
 498
 499         if (ring_req->nr_segments & VSCSIIF_SG_GRANT) {
 500                 err = scsiback_gnttab_data_map_list(pending_req, ring_req->seg,
 501                         pending_req->pages, pending_req->grant_handles,
 502                         nr_segments, GNTMAP_host_map | GNTMAP_readonly);
 503                 if (err)
 504                         return err;
 505                 nr_sgl = nr_segments;
 506                 nr_segments = 0;
 507                 for (i = 0; i < nr_sgl; i++) {
 508                         n_segs = ring_req->seg[i].length /
 509                                  sizeof(struct scsiif_request_segment);
 510                         if ((unsigned)ring_req->seg[i].offset +
 511                             (unsigned)ring_req->seg[i].length > PAGE_SIZE ||
 512                             n_segs * sizeof(struct scsiif_request_segment) !=
 513                             ring_req->seg[i].length)
 514                                 return -EINVAL;
 515                         nr_segments += n_segs;
 516                 }
 517                 if (nr_segments > SG_ALL) {
 518                         pr_debug("invalid nr_seg = %d\n", nr_segments);
 519                         return -EINVAL;
 520                 }
 521         }
 522
 523         /* free of (sgl) in fast_flush_area() */
 524         pending_req->sgl = kmalloc_array(nr_segments,
 525                                         sizeof(struct scatterlist), GFP_KERNEL);
 526         if (!pending_req->sgl)
 527                 return -ENOMEM;
 528
 529         sg_init_table(pending_req->sgl, nr_segments);
 530         pending_req->n_sg = nr_segments;
 531
 532         flags = GNTMAP_host_map;
 533         if (pending_req->sc_data_direction == DMA_TO_DEVICE)
 534                 flags |= GNTMAP_readonly;
 535
 536         pg = pending_req->pages + nr_sgl;
 537         grant = pending_req->grant_handles + nr_sgl;
 538         if (!nr_sgl) {
 539                 seg = ring_req->seg;
 540                 err = scsiback_gnttab_data_map_list(pending_req, seg,
 541                         pg, grant, nr_segments, flags);
 542                 if (err)
 543                         return err;
 544         } else {
 545                 for (i = 0; i < nr_sgl; i++) {
 546                         seg = (struct scsiif_request_segment *)(
 547                               vaddr(pending_req, i) + ring_req->seg[i].offset);
 548                         n_segs = ring_req->seg[i].length /
 549                                  sizeof(struct scsiif_request_segment);
 550                         err = scsiback_gnttab_data_map_list(pending_req, seg,
 551                                 pg, grant, n_segs, flags);
 552                         if (err)
 553                                 return err;
 554                         pg += n_segs;
 555                         grant += n_segs;
 556                 }
 557                 end_seg = vaddr(pending_req, 0) + ring_req->seg[0].offset;
 558                 seg = (struct scsiif_request_segment *)end_seg;
 559                 end_seg += ring_req->seg[0].length;
 560                 pg = pending_req->pages + nr_sgl;
 561         }
 562
 563         for_each_sg(pending_req->sgl, sg, nr_segments, i) {
 564                 sg_set_page(sg, pg[i], seg->length, seg->offset);
 565                 pending_req->data_len += seg->length;
 566                 seg++;
 567                 if (nr_sgl && (unsigned long)seg >= end_seg) {
 568                         i_seg++;
 569                         end_seg = vaddr(pending_req, i_seg) +
 570                                   ring_req->seg[i_seg].offset;
 571                         seg = (struct scsiif_request_segment *)end_seg;
 572                         end_seg += ring_req->seg[i_seg].length;
 573                 }
 574                 if (sg->offset >= PAGE_SIZE ||
 575                     sg->length > PAGE_SIZE ||
 576                     sg->offset + sg->length > PAGE_SIZE)
 577                         return -EINVAL;
 578         }
 579
 580         return 0;
 581 }
 582
 583 static void scsiback_disconnect(struct vscsibk_info *info)
 584 {
 585         wait_event(info->waiting_to_free,
 586                 atomic_read(&info->nr_unreplied_reqs) == 0);
 587
 588         unbind_from_irqhandler(info->irq, info);
 589         info->irq = 0;
 590         xenbus_unmap_ring_vfree(info->dev, info->ring.sring);
 591 }
 592
 593 static void scsiback_device_action(struct vscsibk_pend *pending_req,
 594         enum tcm_tmreq_table act, int tag)
 595 {
 596         struct scsiback_tpg *tpg = pending_req->v2p->tpg;
 597         struct scsiback_nexus *nexus = tpg->tpg_nexus;
 598         struct se_cmd *se_cmd = &pending_req->se_cmd;
 599         u64 unpacked_lun = pending_req->v2p->lun;
 600         int rc, err = FAILED;
 601
 602         init_waitqueue_head(&pending_req->tmr_wait);
 603
 604         rc = target_submit_tmr(&pending_req->se_cmd, nexus->tvn_se_sess,
 605                                &pending_req->sense_buffer[0],
 606                                unpacked_lun, NULL, act, GFP_KERNEL,
 607                                tag, TARGET_SCF_ACK_KREF);
 608         if (rc)
 609                 goto err;
 610
 611         wait_event(pending_req->tmr_wait,
 612                    atomic_read(&pending_req->tmr_complete));
 613
 614         err = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ?
 615                 SUCCESS : FAILED;
 616
 617         scsiback_do_resp_with_sense(NULL, err, 0, pending_req);
 618         transport_generic_free_cmd(&pending_req->se_cmd, 1);
 619         return;
 620
 621 err:
 622         scsiback_do_resp_with_sense(NULL, err, 0, pending_req);
 623 }
 624
 625 /*
 626   Perform virtual to physical translation
 627 */
 628 static struct v2p_entry *scsiback_do_translation(struct vscsibk_info *info,
 629                         struct ids_tuple *v)
 630 {
 631         struct v2p_entry *entry;
 632         struct list_head *head = &(info->v2p_entry_lists);
 633         unsigned long flags;
 634
 635         spin_lock_irqsave(&info->v2p_lock, flags);
 636         list_for_each_entry(entry, head, l) {
 637                 if ((entry->v.chn == v->chn) &&
 638                     (entry->v.tgt == v->tgt) &&
 639                     (entry->v.lun == v->lun)) {
 640                         kref_get(&entry->kref);
 641                         goto out;
 642                 }
 643         }
 644         entry = NULL;
 645
 646 out:
 647         spin_unlock_irqrestore(&info->v2p_lock, flags);
 648         return entry;
 649 }
 650
 651 static struct vscsibk_pend *scsiback_get_pend_req(struct vscsiif_back_ring *ring,
 652                                 struct v2p_entry *v2p)
 653 {
 654         struct scsiback_tpg *tpg = v2p->tpg;
 655         struct scsiback_nexus *nexus = tpg->tpg_nexus;
 656         struct se_session *se_sess = nexus->tvn_se_sess;
 657         struct vscsibk_pend *req;
 658         int tag, i;
 659
 660         tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
 661         if (tag < 0) {
 662                 pr_err("Unable to obtain tag for vscsiif_request\n");
 663                 return ERR_PTR(-ENOMEM);
 664         }
 665
 666         req = &((struct vscsibk_pend *)se_sess->sess_cmd_map)[tag];
 667         memset(req, 0, sizeof(*req));
 668         req->se_cmd.map_tag = tag;
 669
 670         for (i = 0; i < VSCSI_MAX_GRANTS; i++)
 671                 req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
 672
 673         return req;
 674 }
 675
 676 static struct vscsibk_pend *prepare_pending_reqs(struct vscsibk_info *info,
 677                                 struct vscsiif_back_ring *ring,
 678                                 struct vscsiif_request *ring_req)
 679 {
 680         struct vscsibk_pend *pending_req;
 681         struct v2p_entry *v2p;
 682         struct ids_tuple vir;
 683
 684         /* request range check from frontend */
 685         if ((ring_req->sc_data_direction != DMA_BIDIRECTIONAL) &&
 686                 (ring_req->sc_data_direction != DMA_TO_DEVICE) &&
 687                 (ring_req->sc_data_direction != DMA_FROM_DEVICE) &&
 688                 (ring_req->sc_data_direction != DMA_NONE)) {
 689                 pr_debug("invalid parameter data_dir = %d\n",
 690                         ring_req->sc_data_direction);
 691                 return ERR_PTR(-EINVAL);
 692         }
 693         if (ring_req->cmd_len > VSCSIIF_MAX_COMMAND_SIZE) {
 694                 pr_debug("invalid parameter cmd_len = %d\n",
 695                         ring_req->cmd_len);
 696                 return ERR_PTR(-EINVAL);
 697         }
 698
 699         vir.chn = ring_req->channel;
 700         vir.tgt = ring_req->id;
 701         vir.lun = ring_req->lun;
 702
 703         v2p = scsiback_do_translation(info, &vir);
 704         if (!v2p) {
 705                 pr_debug("the v2p of (chn:%d, tgt:%d, lun:%d) doesn't exist.\n",
 706                          vir.chn, vir.tgt, vir.lun);
 707                 return ERR_PTR(-ENODEV);
 708         }
 709
 710         pending_req = scsiback_get_pend_req(ring, v2p);
 711         if (IS_ERR(pending_req)) {
 712                 kref_put(&v2p->kref, scsiback_free_translation_entry);
 713                 return ERR_PTR(-ENOMEM);
 714         }
 715         pending_req->rqid = ring_req->rqid;
 716         pending_req->info = info;
 717         pending_req->v2p = v2p;
 718         pending_req->sc_data_direction = ring_req->sc_data_direction;
 719         pending_req->cmd_len = ring_req->cmd_len;
 720         memcpy(pending_req->cmnd, ring_req->cmnd, pending_req->cmd_len);
 721
 722         return pending_req;
 723 }
 724
 725 static int scsiback_do_cmd_fn(struct vscsibk_info *info,
 726                               unsigned int *eoi_flags)
 727 {
 728         struct vscsiif_back_ring *ring = &info->ring;
 729         struct vscsiif_request ring_req;
 730         struct vscsibk_pend *pending_req;
 731         RING_IDX rc, rp;
 732         int more_to_do;
 733         uint32_t result;
 734
 735         rc = ring->req_cons;
 736         rp = ring->sring->req_prod;
 737         rmb();  /* guest system is accessing ring, too */
 738
 739         if (RING_REQUEST_PROD_OVERFLOW(ring, rp)) {
 740                 rc = ring->rsp_prod_pvt;
 741                 pr_warn("Dom%d provided bogus ring requests (%#x - %#x = %u). Halting ring processing\n",
 742                            info->domid, rp, rc, rp - rc);
 743                 return -EINVAL;
 744         }
 745
 746         while ((rc != rp)) {
 747                 *eoi_flags &= ~XEN_EOI_FLAG_SPURIOUS;
 748
 749                 if (RING_REQUEST_CONS_OVERFLOW(ring, rc))
 750                         break;
 751
 752                 RING_COPY_REQUEST(ring, rc, &ring_req);
 753                 ring->req_cons = ++rc;
 754
 755                 pending_req = prepare_pending_reqs(info, ring, &ring_req);
 756                 if (IS_ERR(pending_req)) {
 757                         switch (PTR_ERR(pending_req)) {
 758                         case -ENODEV:
 759                                 result = DID_NO_CONNECT;
 760                                 break;
 761                         default:
 762                                 result = DRIVER_ERROR;
 763                                 break;
 764                         }
 765                         scsiback_send_response(info, NULL, result << 24, 0,
 766                                                ring_req.rqid);
 767                         return 1;
 768                 }
 769
 770                 switch (ring_req.act) {
 771                 case VSCSIIF_ACT_SCSI_CDB:
 772                         if (scsiback_gnttab_data_map(&ring_req, pending_req)) {
 773                                 scsiback_fast_flush_area(pending_req);
 774                                 scsiback_do_resp_with_sense(NULL,
 775                                                 DRIVER_ERROR << 24, 0, pending_req);
 776                                 transport_generic_free_cmd(&pending_req->se_cmd, 0);
 777                         } else {
 778                                 scsiback_cmd_exec(pending_req);
 779                         }
 780                         break;
 781                 case VSCSIIF_ACT_SCSI_ABORT:
 782                         scsiback_device_action(pending_req, TMR_ABORT_TASK,
 783                                 ring_req.ref_rqid);
 784                         break;
 785                 case VSCSIIF_ACT_SCSI_RESET:
 786                         scsiback_device_action(pending_req, TMR_LUN_RESET, 0);
 787                         break;
 788                 default:
 789                         pr_err_ratelimited("invalid request\n");
 790                         scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24, 0,
 791                                                     pending_req);
 792                         transport_generic_free_cmd(&pending_req->se_cmd, 0);
 793                         break;
 794                 }
 795
 796                 /* Yield point for this unbounded loop. */
 797                 cond_resched();
 798         }
 799
 800         RING_FINAL_CHECK_FOR_REQUESTS(&info->ring, more_to_do);
 801         return more_to_do;
 802 }
 803
 804 static irqreturn_t scsiback_irq_fn(int irq, void *dev_id)
 805 {
 806         struct vscsibk_info *info = dev_id;
 807         int rc;
 808         unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 809
 810         while ((rc = scsiback_do_cmd_fn(info, &eoi_flags)) > 0)
 811                 cond_resched();
 812
 813         /* In case of a ring error we keep the event channel masked. */
 814         if (!rc)
 815                 xen_irq_lateeoi(irq, eoi_flags);
 816
 817         return IRQ_HANDLED;
 818 }
 819
 820 static int scsiback_init_sring(struct vscsibk_info *info, grant_ref_t ring_ref,
 821                         evtchn_port_t evtchn)
 822 {
 823         void *area;
 824         struct vscsiif_sring *sring;
 825         int err;
 826
 827         if (info->irq)
 828                 return -1;
 829
 830         err = xenbus_map_ring_valloc(info->dev, &ring_ref, 1, &area);
 831         if (err)
 832                 return err;
 833
 834         sring = (struct vscsiif_sring *)area;
 835         BACK_RING_INIT(&info->ring, sring, PAGE_SIZE);
 836
 837         err = bind_interdomain_evtchn_to_irq_lateeoi(info->domid, evtchn);
 838         if (err < 0)
 839                 goto unmap_page;
 840
 841         info->irq = err;
 842
 843         err = request_threaded_irq(info->irq, NULL, scsiback_irq_fn,
 844                                    IRQF_ONESHOT, "vscsiif-backend", info);
 845         if (err)
 846                 goto free_irq;
 847
 848         return 0;
 849
 850 free_irq:
 851         unbind_from_irqhandler(info->irq, info);
 852         info->irq = 0;
 853 unmap_page:
 854         xenbus_unmap_ring_vfree(info->dev, area);
 855
 856         return err;
 857 }
 858
 859 static int scsiback_map(struct vscsibk_info *info)
 860 {
 861         struct xenbus_device *dev = info->dev;
 862         unsigned int ring_ref, evtchn;
 863         int err;
 864
 865         err = xenbus_gather(XBT_NIL, dev->otherend,
 866                         "ring-ref", "%u", &ring_ref,
 867                         "event-channel", "%u", &evtchn, NULL);
 868         if (err) {
 869                 xenbus_dev_fatal(dev, err, "reading %s ring", dev->otherend);
 870                 return err;
 871         }
 872
 873         return scsiback_init_sring(info, ring_ref, evtchn);
 874 }
 875
 876 /*
 877   Check for a translation entry being present
 878 */
 879 static struct v2p_entry *scsiback_chk_translation_entry(
 880         struct vscsibk_info *info, struct ids_tuple *v)
 881 {
 882         struct list_head *head = &(info->v2p_entry_lists);
 883         struct v2p_entry *entry;
 884
 885         list_for_each_entry(entry, head, l)
 886                 if ((entry->v.chn == v->chn) &&
 887                     (entry->v.tgt == v->tgt) &&
 888                     (entry->v.lun == v->lun))
 889                         return entry;
 890
 891         return NULL;
 892 }
 893
 894 /*
 895   Add a new translation entry
 896 */
 897 static int scsiback_add_translation_entry(struct vscsibk_info *info,
 898                                           char *phy, struct ids_tuple *v)
 899 {
 900         int err = 0;
 901         struct v2p_entry *new;
 902         unsigned long flags;
 903         char *lunp;
 904         unsigned long long unpacked_lun;
 905         struct se_lun *se_lun;
 906         struct scsiback_tpg *tpg_entry, *tpg = NULL;
 907         char *error = "doesn't exist";
 908
 909         lunp = strrchr(phy, ':');
 910         if (!lunp) {
 911                 pr_err("illegal format of physical device %s\n", phy);
 912                 return -EINVAL;
 913         }
 914         *lunp = 0;
 915         lunp++;
 916         err = kstrtoull(lunp, 10, &unpacked_lun);
 917         if (err < 0) {
 918                 pr_err("lun number not valid: %s\n", lunp);
 919                 return err;
 920         }
 921
 922         mutex_lock(&scsiback_mutex);
 923         list_for_each_entry(tpg_entry, &scsiback_list, tv_tpg_list) {
 924                 if (!strcmp(phy, tpg_entry->tport->tport_name) ||
 925                     !strcmp(phy, tpg_entry->param_alias)) {
 926                         mutex_lock(&tpg_entry->se_tpg.tpg_lun_mutex);
 927                         hlist_for_each_entry(se_lun, &tpg_entry->se_tpg.tpg_lun_hlist, link) {
 928                                 if (se_lun->unpacked_lun == unpacked_lun) {
 929                                         if (!tpg_entry->tpg_nexus)
 930                                                 error = "nexus undefined";
 931                                         else
 932                                                 tpg = tpg_entry;
 933                                         break;
 934                                 }
 935                         }
 936                         mutex_unlock(&tpg_entry->se_tpg.tpg_lun_mutex);
 937                         break;
 938                 }
 939         }
 940         if (tpg) {
 941                 mutex_lock(&tpg->tv_tpg_mutex);
 942                 tpg->tv_tpg_fe_count++;
 943                 mutex_unlock(&tpg->tv_tpg_mutex);
 944         }
 945         mutex_unlock(&scsiback_mutex);
 946
 947         if (!tpg) {
 948                 pr_err("%s:%llu %s\n", phy, unpacked_lun, error);
 949                 return -ENODEV;
 950         }
 951
 952         new = kmalloc(sizeof(struct v2p_entry), GFP_KERNEL);
 953         if (new == NULL) {
 954                 err = -ENOMEM;
 955                 goto out_free;
 956         }
 957
 958         spin_lock_irqsave(&info->v2p_lock, flags);
 959
 960         /* Check double assignment to identical virtual ID */
 961         if (scsiback_chk_translation_entry(info, v)) {
 962                 pr_warn("Virtual ID is already used. Assignment was not performed.\n");
 963                 err = -EEXIST;
 964                 goto out;
 965         }
 966
 967         /* Create a new translation entry and add to the list */
 968         kref_init(&new->kref);
 969         new->v = *v;
 970         new->tpg = tpg;
 971         new->lun = unpacked_lun;
 972         list_add_tail(&new->l, &info->v2p_entry_lists);
 973
 974 out:
 975         spin_unlock_irqrestore(&info->v2p_lock, flags);
 976
 977 out_free:
 978         if (err) {
 979                 mutex_lock(&tpg->tv_tpg_mutex);
 980                 tpg->tv_tpg_fe_count--;
 981                 mutex_unlock(&tpg->tv_tpg_mutex);
 982                 kfree(new);
 983         }
 984
 985         return err;
 986 }
 987
 988 static void __scsiback_del_translation_entry(struct v2p_entry *entry)
 989 {
 990         list_del(&entry->l);
 991         kref_put(&entry->kref, scsiback_free_translation_entry);
 992 }
 993
 994 /*
 995   Delete the translation entry specified
 996 */
 997 static int scsiback_del_translation_entry(struct vscsibk_info *info,
 998                                           struct ids_tuple *v)
 999 {
1000         struct v2p_entry *entry;
1001         unsigned long flags;
1002         int ret = 0;
1003
1004         spin_lock_irqsave(&info->v2p_lock, flags);
1005         /* Find out the translation entry specified */
1006         entry = scsiback_chk_translation_entry(info, v);
1007         if (entry)
1008                 __scsiback_del_translation_entry(entry);
1009         else
1010                 ret = -ENOENT;
1011
1012         spin_unlock_irqrestore(&info->v2p_lock, flags);
1013         return ret;
1014 }
1015
1016 static void scsiback_do_add_lun(struct vscsibk_info *info, const char *state,
1017                                 char *phy, struct ids_tuple *vir, int try)
1018 {
1019         struct v2p_entry *entry;
1020         unsigned long flags;
1021         int err;
1022
1023         if (try) {
1024                 spin_lock_irqsave(&info->v2p_lock, flags);
1025                 entry = scsiback_chk_translation_entry(info, vir);
1026                 spin_unlock_irqrestore(&info->v2p_lock, flags);
1027                 if (entry)
1028                         return;
1029         }
1030         if (!scsiback_add_translation_entry(info, phy, vir)) {
1031                 if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
1032                                   "%d", XenbusStateInitialised)) {
1033                         pr_err("xenbus_printf error %s\n", state);
1034                         scsiback_del_translation_entry(info, vir);
1035                 }
1036         } else if (!try) {
1037                 err = xenbus_printf(XBT_NIL, info->dev->nodename, state,
1038                               "%d", XenbusStateClosed);
1039                 if (err)
1040                         xenbus_dev_error(info->dev, err,
1041                                 "%s: writing %s", __func__, state);
1042         }
1043 }
1044
1045 static void scsiback_do_del_lun(struct vscsibk_info *info, const char *state,
1046                                 struct ids_tuple *vir)
1047 {
1048         if (!scsiback_del_translation_entry(info, vir)) {
1049                 if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
1050                                   "%d", XenbusStateClosed))
1051                         pr_err("xenbus_printf error %s\n", state);
1052         }
1053 }
1054
1055 #define VSCSIBACK_OP_ADD_OR_DEL_LUN     1
1056 #define VSCSIBACK_OP_UPDATEDEV_STATE    2
1057
1058 static void scsiback_do_1lun_hotplug(struct vscsibk_info *info, int op,
1059                                      char *ent)
1060 {
1061         int err;
1062         struct ids_tuple vir;
1063         char *val;
1064         int device_state;
1065         char phy[VSCSI_NAMELEN];
1066         char str[64];
1067         char state[64];
1068         struct xenbus_device *dev = info->dev;
1069
1070         /* read status */
1071         snprintf(state, sizeof(state), "vscsi-devs/%s/state", ent);
1072         err = xenbus_scanf(XBT_NIL, dev->nodename, state, "%u", &device_state);
1073         if (XENBUS_EXIST_ERR(err))
1074                 return;
1075
1076         /* physical SCSI device */
1077         snprintf(str, sizeof(str), "vscsi-devs/%s/p-dev", ent);
1078         val = xenbus_read(XBT_NIL, dev->nodename, str, NULL);
1079         if (IS_ERR(val)) {
1080                 err = xenbus_printf(XBT_NIL, dev->nodename, state,
1081                               "%d", XenbusStateClosed);
1082                 if (err)
1083                         xenbus_dev_error(info->dev, err,
1084                                 "%s: writing %s", __func__, state);
1085                 return;
1086         }
1087         strlcpy(phy, val, VSCSI_NAMELEN);
1088         kfree(val);
1089
1090         /* virtual SCSI device */
1091         snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", ent);
1092         err = xenbus_scanf(XBT_NIL, dev->nodename, str, "%u:%u:%u:%u",
1093                            &vir.hst, &vir.chn, &vir.tgt, &vir.lun);
1094         if (XENBUS_EXIST_ERR(err)) {
1095                 err = xenbus_printf(XBT_NIL, dev->nodename, state,
1096                               "%d", XenbusStateClosed);
1097                 if (err)
1098                         xenbus_dev_error(info->dev, err,
1099                                 "%s: writing %s", __func__, state);
1100                 return;
1101         }
1102
1103         switch (op) {
1104         case VSCSIBACK_OP_ADD_OR_DEL_LUN:
1105                 switch (device_state) {
1106                 case XenbusStateInitialising:
1107                         scsiback_do_add_lun(info, state, phy, &vir, 0);
1108                         break;
1109                 case XenbusStateConnected:
1110                         scsiback_do_add_lun(info, state, phy, &vir, 1);
1111                         break;
1112                 case XenbusStateClosing:
1113                         scsiback_do_del_lun(info, state, &vir);
1114                         break;
1115                 default:
1116                         break;
1117                 }
1118                 break;
1119
1120         case VSCSIBACK_OP_UPDATEDEV_STATE:
1121                 if (device_state == XenbusStateInitialised) {
1122                         /* modify vscsi-devs/dev-x/state */
1123                         if (xenbus_printf(XBT_NIL, dev->nodename, state,
1124                                           "%d", XenbusStateConnected)) {
1125                                 pr_err("xenbus_printf error %s\n", str);
1126                                 scsiback_del_translation_entry(info, &vir);
1127                                 xenbus_printf(XBT_NIL, dev->nodename, state,
1128                                               "%d", XenbusStateClosed);
1129                         }
1130                 }
1131                 break;
1132         /* When it is necessary, processing is added here. */
1133         default:
1134                 break;
1135         }
1136 }
1137
1138 static void scsiback_do_lun_hotplug(struct vscsibk_info *info, int op)
1139 {
1140         int i;
1141         char **dir;
1142         unsigned int ndir = 0;
1143
1144         dir = xenbus_directory(XBT_NIL, info->dev->nodename, "vscsi-devs",
1145                                &ndir);
1146         if (IS_ERR(dir))
1147                 return;
1148
1149         for (i = 0; i < ndir; i++)
1150                 scsiback_do_1lun_hotplug(info, op, dir[i]);
1151
1152         kfree(dir);
1153 }
1154
1155 static void scsiback_frontend_changed(struct xenbus_device *dev,
1156                                         enum xenbus_state frontend_state)
1157 {
1158         struct vscsibk_info *info = dev_get_drvdata(&dev->dev);
1159
1160         switch (frontend_state) {
1161         case XenbusStateInitialising:
1162                 break;
1163
1164         case XenbusStateInitialised:
1165                 if (scsiback_map(info))
1166                         break;
1167
1168                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
1169                 xenbus_switch_state(dev, XenbusStateConnected);
1170                 break;
1171
1172         case XenbusStateConnected:
1173                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_UPDATEDEV_STATE);
1174
1175                 if (dev->state == XenbusStateConnected)
1176                         break;
1177
1178                 xenbus_switch_state(dev, XenbusStateConnected);
1179                 break;
1180
1181         case XenbusStateClosing:
1182                 if (info->irq)
1183                         scsiback_disconnect(info);
1184
1185                 xenbus_switch_state(dev, XenbusStateClosing);
1186                 break;
1187
1188         case XenbusStateClosed:
1189                 xenbus_switch_state(dev, XenbusStateClosed);
1190                 if (xenbus_dev_is_online(dev))
1191                         break;
1192                 /* fall through if not online */
1193         case XenbusStateUnknown:
1194                 device_unregister(&dev->dev);
1195                 break;
1196
1197         case XenbusStateReconfiguring:
1198                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
1199                 xenbus_switch_state(dev, XenbusStateReconfigured);
1200
1201                 break;
1202
1203         default:
1204                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
1205                                         frontend_state);
1206                 break;
1207         }
1208 }
1209
1210 /*
1211   Release the translation entry specfied
1212 */
1213 static void scsiback_release_translation_entry(struct vscsibk_info *info)
1214 {
1215         struct v2p_entry *entry, *tmp;
1216         struct list_head *head = &(info->v2p_entry_lists);
1217         unsigned long flags;
1218
1219         spin_lock_irqsave(&info->v2p_lock, flags);
1220
1221         list_for_each_entry_safe(entry, tmp, head, l)
1222                 __scsiback_del_translation_entry(entry);
1223
1224         spin_unlock_irqrestore(&info->v2p_lock, flags);
1225 }
1226
1227 static int scsiback_remove(struct xenbus_device *dev)
1228 {
1229         struct vscsibk_info *info = dev_get_drvdata(&dev->dev);
1230
1231         if (info->irq)
1232                 scsiback_disconnect(info);
1233
1234         scsiback_release_translation_entry(info);
1235
1236         dev_set_drvdata(&dev->dev, NULL);
1237
1238         return 0;
1239 }
1240
1241 static int scsiback_probe(struct xenbus_device *dev,
1242                            const struct xenbus_device_id *id)
1243 {
1244         int err;
1245
1246         struct vscsibk_info *info = kzalloc(sizeof(struct vscsibk_info),
1247                                             GFP_KERNEL);
1248
1249         pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
1250
1251         if (!info) {
1252                 xenbus_dev_fatal(dev, -ENOMEM, "allocating backend structure");
1253                 return -ENOMEM;
1254         }
1255         info->dev = dev;
1256         dev_set_drvdata(&dev->dev, info);
1257
1258         info->domid = dev->otherend_id;
1259         spin_lock_init(&info->ring_lock);
1260         atomic_set(&info->nr_unreplied_reqs, 0);
1261         init_waitqueue_head(&info->waiting_to_free);
1262         info->dev = dev;
1263         info->irq = 0;
1264         INIT_LIST_HEAD(&info->v2p_entry_lists);
1265         spin_lock_init(&info->v2p_lock);
1266
1267         err = xenbus_printf(XBT_NIL, dev->nodename, "feature-sg-grant", "%u",
1268                             SG_ALL);
1269         if (err)
1270                 xenbus_dev_error(dev, err, "writing feature-sg-grant");
1271
1272         err = xenbus_switch_state(dev, XenbusStateInitWait);
1273         if (err)
1274                 goto fail;
1275
1276         return 0;
1277
1278 fail:
1279         pr_warn("%s failed\n", __func__);
1280         scsiback_remove(dev);
1281
1282         return err;
1283 }
1284
1285 static char *scsiback_dump_proto_id(struct scsiback_tport *tport)
1286 {
1287         switch (tport->tport_proto_id) {
1288         case SCSI_PROTOCOL_SAS:
1289                 return "SAS";
1290         case SCSI_PROTOCOL_FCP:
1291                 return "FCP";
1292         case SCSI_PROTOCOL_ISCSI:
1293                 return "iSCSI";
1294         default:
1295                 break;
1296         }
1297
1298         return "Unknown";
1299 }
1300
1301 static char *scsiback_get_fabric_wwn(struct se_portal_group *se_tpg)
1302 {
1303         struct scsiback_tpg *tpg = container_of(se_tpg,
1304                                 struct scsiback_tpg, se_tpg);
1305         struct scsiback_tport *tport = tpg->tport;
1306
1307         return &tport->tport_name[0];
1308 }
1309
1310 static u16 scsiback_get_tag(struct se_portal_group *se_tpg)
1311 {
1312         struct scsiback_tpg *tpg = container_of(se_tpg,
1313                                 struct scsiback_tpg, se_tpg);
1314         return tpg->tport_tpgt;
1315 }
1316
1317 static struct se_wwn *
1318 scsiback_make_tport(struct target_fabric_configfs *tf,
1319                      struct config_group *group,
1320                      const char *name)
1321 {
1322         struct scsiback_tport *tport;
1323         char *ptr;
1324         u64 wwpn = 0;
1325         int off = 0;
1326
1327         tport = kzalloc(sizeof(struct scsiback_tport), GFP_KERNEL);
1328         if (!tport)
1329                 return ERR_PTR(-ENOMEM);
1330
1331         tport->tport_wwpn = wwpn;
1332         /*
1333          * Determine the emulated Protocol Identifier and Target Port Name
1334          * based on the incoming configfs directory name.
1335          */
1336         ptr = strstr(name, "naa.");
1337         if (ptr) {
1338                 tport->tport_proto_id = SCSI_PROTOCOL_SAS;
1339                 goto check_len;
1340         }
1341         ptr = strstr(name, "fc.");
1342         if (ptr) {
1343                 tport->tport_proto_id = SCSI_PROTOCOL_FCP;
1344                 off = 3; /* Skip over "fc." */
1345                 goto check_len;
1346         }
1347         ptr = strstr(name, "iqn.");
1348         if (ptr) {
1349                 tport->tport_proto_id = SCSI_PROTOCOL_ISCSI;
1350                 goto check_len;
1351         }
1352
1353         pr_err("Unable to locate prefix for emulated Target Port: %s\n", name);
1354         kfree(tport);
1355         return ERR_PTR(-EINVAL);
1356
1357 check_len:
1358         if (strlen(name) >= VSCSI_NAMELEN) {
1359                 pr_err("Emulated %s Address: %s, exceeds max: %d\n", name,
1360                         scsiback_dump_proto_id(tport), VSCSI_NAMELEN);
1361                 kfree(tport);
1362                 return ERR_PTR(-EINVAL);
1363         }
1364         snprintf(&tport->tport_name[0], VSCSI_NAMELEN, "%s", &name[off]);
1365
1366         pr_debug("Allocated emulated Target %s Address: %s\n",
1367                  scsiback_dump_proto_id(tport), name);
1368
1369         return &tport->tport_wwn;
1370 }
1371
1372 static void scsiback_drop_tport(struct se_wwn *wwn)
1373 {
1374         struct scsiback_tport *tport = container_of(wwn,
1375                                 struct scsiback_tport, tport_wwn);
1376
1377         pr_debug("Deallocating emulated Target %s Address: %s\n",
1378                  scsiback_dump_proto_id(tport), tport->tport_name);
1379
1380         kfree(tport);
1381 }
1382
1383 static u32 scsiback_tpg_get_inst_index(struct se_portal_group *se_tpg)
1384 {
1385         return 1;
1386 }
1387
1388 static int scsiback_check_stop_free(struct se_cmd *se_cmd)
1389 {
1390         return transport_generic_free_cmd(se_cmd, 0);
1391 }
1392
1393 static void scsiback_release_cmd(struct se_cmd *se_cmd)
1394 {
1395         struct se_session *se_sess = se_cmd->se_sess;
1396
1397         percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag);
1398 }
1399
1400 static u32 scsiback_sess_get_index(struct se_session *se_sess)
1401 {
1402         return 0;
1403 }
1404
1405 static int scsiback_write_pending(struct se_cmd *se_cmd)
1406 {
1407         /* Go ahead and process the write immediately */
1408         target_execute_cmd(se_cmd);
1409
1410         return 0;
1411 }
1412
1413 static int scsiback_write_pending_status(struct se_cmd *se_cmd)
1414 {
1415         return 0;
1416 }
1417
1418 static void scsiback_set_default_node_attrs(struct se_node_acl *nacl)
1419 {
1420 }
1421
1422 static int scsiback_get_cmd_state(struct se_cmd *se_cmd)
1423 {
1424         return 0;
1425 }
1426
1427 static int scsiback_queue_data_in(struct se_cmd *se_cmd)
1428 {
1429         struct vscsibk_pend *pending_req = container_of(se_cmd,
1430                                 struct vscsibk_pend, se_cmd);
1431
1432         pending_req->result = SAM_STAT_GOOD;
1433         scsiback_cmd_done(pending_req);
1434         return 0;
1435 }
1436
1437 static int scsiback_queue_status(struct se_cmd *se_cmd)
1438 {
1439         struct vscsibk_pend *pending_req = container_of(se_cmd,
1440                                 struct vscsibk_pend, se_cmd);
1441
1442         if (se_cmd->sense_buffer &&
1443             ((se_cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
1444              (se_cmd->se_cmd_flags & SCF_EMULATED_TASK_SENSE)))
1445                 pending_req->result = (DRIVER_SENSE << 24) |
1446                                       SAM_STAT_CHECK_CONDITION;
1447         else
1448                 pending_req->result = se_cmd->scsi_status;
1449
1450         scsiback_cmd_done(pending_req);
1451         return 0;
1452 }
1453
1454 static void scsiback_queue_tm_rsp(struct se_cmd *se_cmd)
1455 {
1456         struct vscsibk_pend *pending_req = container_of(se_cmd,
1457                                 struct vscsibk_pend, se_cmd);
1458
1459         atomic_set(&pending_req->tmr_complete, 1);
1460         wake_up(&pending_req->tmr_wait);
1461 }
1462
1463 static void scsiback_aborted_task(struct se_cmd *se_cmd)
1464 {
1465 }
1466
1467 static ssize_t scsiback_tpg_param_alias_show(struct config_item *item,
1468                                              char *page)
1469 {
1470         struct se_portal_group *se_tpg = param_to_tpg(item);
1471         struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
1472                                                 se_tpg);
1473         ssize_t rb;
1474
1475         mutex_lock(&tpg->tv_tpg_mutex);
1476         rb = snprintf(page, PAGE_SIZE, "%s\n", tpg->param_alias);
1477         mutex_unlock(&tpg->tv_tpg_mutex);
1478
1479         return rb;
1480 }
1481
1482 static ssize_t scsiback_tpg_param_alias_store(struct config_item *item,
1483                                               const char *page, size_t count)
1484 {
1485         struct se_portal_group *se_tpg = param_to_tpg(item);
1486         struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
1487                                                 se_tpg);
1488         int len;
1489
1490         if (strlen(page) >= VSCSI_NAMELEN) {
1491                 pr_err("param alias: %s, exceeds max: %d\n", page,
1492                         VSCSI_NAMELEN);
1493                 return -EINVAL;
1494         }
1495
1496         mutex_lock(&tpg->tv_tpg_mutex);
1497         len = snprintf(tpg->param_alias, VSCSI_NAMELEN, "%s", page);
1498         if (tpg->param_alias[len - 1] == '\n')
1499                 tpg->param_alias[len - 1] = '\0';
1500         mutex_unlock(&tpg->tv_tpg_mutex);
1501
1502         return count;
1503 }
1504
1505 CONFIGFS_ATTR(scsiback_tpg_param_, alias);
1506
1507 static struct configfs_attribute *scsiback_param_attrs[] = {
1508         &scsiback_tpg_param_attr_alias,
1509         NULL,
1510 };
1511
1512 static int scsiback_alloc_sess_cb(struct se_portal_group *se_tpg,
1513                                   struct se_session *se_sess, void *p)
1514 {
1515         struct scsiback_tpg *tpg = container_of(se_tpg,
1516                                 struct scsiback_tpg, se_tpg);
1517
1518         tpg->tpg_nexus = p;
1519         return 0;
1520 }
1521
1522 static int scsiback_make_nexus(struct scsiback_tpg *tpg,
1523                                 const char *name)
1524 {
1525         struct scsiback_nexus *tv_nexus;
1526         int ret = 0;
1527
1528         mutex_lock(&tpg->tv_tpg_mutex);
1529         if (tpg->tpg_nexus) {
1530                 pr_debug("tpg->tpg_nexus already exists\n");
1531                 ret = -EEXIST;
1532                 goto out_unlock;
1533         }
1534
1535         tv_nexus = kzalloc(sizeof(struct scsiback_nexus), GFP_KERNEL);
1536         if (!tv_nexus) {
1537                 ret = -ENOMEM;
1538                 goto out_unlock;
1539         }
1540
1541         tv_nexus->tvn_se_sess = target_alloc_session(&tpg->se_tpg,
1542                                                      VSCSI_DEFAULT_SESSION_TAGS,
1543                                                      sizeof(struct vscsibk_pend),
1544                                                      TARGET_PROT_NORMAL, name,
1545                                                      tv_nexus, scsiback_alloc_sess_cb);
1546         if (IS_ERR(tv_nexus->tvn_se_sess)) {
1547                 kfree(tv_nexus);
1548                 ret = -ENOMEM;
1549                 goto out_unlock;
1550         }
1551
1552 out_unlock:
1553         mutex_unlock(&tpg->tv_tpg_mutex);
1554         return ret;
1555 }
1556
1557 static int scsiback_drop_nexus(struct scsiback_tpg *tpg)
1558 {
1559         struct se_session *se_sess;
1560         struct scsiback_nexus *tv_nexus;
1561
1562         mutex_lock(&tpg->tv_tpg_mutex);
1563         tv_nexus = tpg->tpg_nexus;
1564         if (!tv_nexus) {
1565                 mutex_unlock(&tpg->tv_tpg_mutex);
1566                 return -ENODEV;
1567         }
1568
1569         se_sess = tv_nexus->tvn_se_sess;
1570         if (!se_sess) {
1571                 mutex_unlock(&tpg->tv_tpg_mutex);
1572                 return -ENODEV;
1573         }
1574
1575         if (tpg->tv_tpg_port_count != 0) {
1576                 mutex_unlock(&tpg->tv_tpg_mutex);
1577                 pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG port count: %d\n",
1578                         tpg->tv_tpg_port_count);
1579                 return -EBUSY;
1580         }
1581
1582         if (tpg->tv_tpg_fe_count != 0) {
1583                 mutex_unlock(&tpg->tv_tpg_mutex);
1584                 pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG frontend count: %d\n",
1585                         tpg->tv_tpg_fe_count);
1586                 return -EBUSY;
1587         }
1588
1589         pr_debug("Removing I_T Nexus to emulated %s Initiator Port: %s\n",
1590                 scsiback_dump_proto_id(tpg->tport),
1591                 tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
1592
1593         /*
1594          * Release the SCSI I_T Nexus to the emulated xen-pvscsi Target Port
1595          */
1596         transport_deregister_session(tv_nexus->tvn_se_sess);
1597         tpg->tpg_nexus = NULL;
1598         mutex_unlock(&tpg->tv_tpg_mutex);
1599
1600         kfree(tv_nexus);
1601         return 0;
1602 }
1603
1604 static ssize_t scsiback_tpg_nexus_show(struct config_item *item, char *page)
1605 {
1606         struct se_portal_group *se_tpg = to_tpg(item);
1607         struct scsiback_tpg *tpg = container_of(se_tpg,
1608                                 struct scsiback_tpg, se_tpg);
1609         struct scsiback_nexus *tv_nexus;
1610         ssize_t ret;
1611
1612         mutex_lock(&tpg->tv_tpg_mutex);
1613         tv_nexus = tpg->tpg_nexus;
1614         if (!tv_nexus) {
1615                 mutex_unlock(&tpg->tv_tpg_mutex);
1616                 return -ENODEV;
1617         }
1618         ret = snprintf(page, PAGE_SIZE, "%s\n",
1619                         tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
1620         mutex_unlock(&tpg->tv_tpg_mutex);
1621
1622         return ret;
1623 }
1624
1625 static ssize_t scsiback_tpg_nexus_store(struct config_item *item,
1626                 const char *page, size_t count)
1627 {
1628         struct se_portal_group *se_tpg = to_tpg(item);
1629         struct scsiback_tpg *tpg = container_of(se_tpg,
1630                                 struct scsiback_tpg, se_tpg);
1631         struct scsiback_tport *tport_wwn = tpg->tport;
1632         unsigned char i_port[VSCSI_NAMELEN], *ptr, *port_ptr;
1633         int ret;
1634         /*
1635          * Shutdown the active I_T nexus if 'NULL' is passed.
1636          */
1637         if (!strncmp(page, "NULL", 4)) {
1638                 ret = scsiback_drop_nexus(tpg);
1639                 return (!ret) ? count : ret;
1640         }
1641         /*
1642          * Otherwise make sure the passed virtual Initiator port WWN matches
1643          * the fabric protocol_id set in scsiback_make_tport(), and call
1644          * scsiback_make_nexus().
1645          */
1646         if (strlen(page) >= VSCSI_NAMELEN) {
1647                 pr_err("Emulated NAA Sas Address: %s, exceeds max: %d\n",
1648                         page, VSCSI_NAMELEN);
1649                 return -EINVAL;
1650         }
1651         snprintf(&i_port[0], VSCSI_NAMELEN, "%s", page);
1652
1653         ptr = strstr(i_port, "naa.");
1654         if (ptr) {
1655                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_SAS) {
1656                         pr_err("Passed SAS Initiator Port %s does not match target port protoid: %s\n",
1657                                 i_port, scsiback_dump_proto_id(tport_wwn));
1658                         return -EINVAL;
1659                 }
1660                 port_ptr = &i_port[0];
1661                 goto check_newline;
1662         }
1663         ptr = strstr(i_port, "fc.");
1664         if (ptr) {
1665                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_FCP) {
1666                         pr_err("Passed FCP Initiator Port %s does not match target port protoid: %s\n",
1667                                 i_port, scsiback_dump_proto_id(tport_wwn));
1668                         return -EINVAL;
1669                 }
1670                 port_ptr = &i_port[3]; /* Skip over "fc." */
1671                 goto check_newline;
1672         }
1673         ptr = strstr(i_port, "iqn.");
1674         if (ptr) {
1675                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_ISCSI) {
1676                         pr_err("Passed iSCSI Initiator Port %s does not match target port protoid: %s\n",
1677                                 i_port, scsiback_dump_proto_id(tport_wwn));
1678                         return -EINVAL;
1679                 }
1680                 port_ptr = &i_port[0];
1681                 goto check_newline;
1682         }
1683         pr_err("Unable to locate prefix for emulated Initiator Port: %s\n",
1684                 i_port);
1685         return -EINVAL;
1686         /*
1687          * Clear any trailing newline for the NAA WWN
1688          */
1689 check_newline:
1690         if (i_port[strlen(i_port) - 1] == '\n')
1691                 i_port[strlen(i_port) - 1] = '\0';
1692
1693         ret = scsiback_make_nexus(tpg, port_ptr);
1694         if (ret < 0)
1695                 return ret;
1696
1697         return count;
1698 }
1699
1700 CONFIGFS_ATTR(scsiback_tpg_, nexus);
1701
1702 static struct configfs_attribute *scsiback_tpg_attrs[] = {
1703         &scsiback_tpg_attr_nexus,
1704         NULL,
1705 };
1706
1707 static ssize_t
1708 scsiback_wwn_version_show(struct config_item *item, char *page)
1709 {
1710         return sprintf(page, "xen-pvscsi fabric module %s on %s/%s on "
1711                 UTS_RELEASE"\n",
1712                 VSCSI_VERSION, utsname()->sysname, utsname()->machine);
1713 }
1714
1715 CONFIGFS_ATTR_RO(scsiback_wwn_, version);
1716
1717 static struct configfs_attribute *scsiback_wwn_attrs[] = {
1718         &scsiback_wwn_attr_version,
1719         NULL,
1720 };
1721
1722 static char *scsiback_get_fabric_name(void)
1723 {
1724         return "xen-pvscsi";
1725 }
1726
1727 static int scsiback_port_link(struct se_portal_group *se_tpg,
1728                                struct se_lun *lun)
1729 {
1730         struct scsiback_tpg *tpg = container_of(se_tpg,
1731                                 struct scsiback_tpg, se_tpg);
1732
1733         mutex_lock(&tpg->tv_tpg_mutex);
1734         tpg->tv_tpg_port_count++;
1735         mutex_unlock(&tpg->tv_tpg_mutex);
1736
1737         return 0;
1738 }
1739
1740 static void scsiback_port_unlink(struct se_portal_group *se_tpg,
1741                                   struct se_lun *lun)
1742 {
1743         struct scsiback_tpg *tpg = container_of(se_tpg,
1744                                 struct scsiback_tpg, se_tpg);
1745
1746         mutex_lock(&tpg->tv_tpg_mutex);
1747         tpg->tv_tpg_port_count--;
1748         mutex_unlock(&tpg->tv_tpg_mutex);
1749 }
1750
1751 static struct se_portal_group *
1752 scsiback_make_tpg(struct se_wwn *wwn,
1753                    struct config_group *group,
1754                    const char *name)
1755 {
1756         struct scsiback_tport *tport = container_of(wwn,
1757                         struct scsiback_tport, tport_wwn);
1758
1759         struct scsiback_tpg *tpg;
1760         u16 tpgt;
1761         int ret;
1762
1763         if (strstr(name, "tpgt_") != name)
1764                 return ERR_PTR(-EINVAL);
1765         ret = kstrtou16(name + 5, 10, &tpgt);
1766         if (ret)
1767                 return ERR_PTR(ret);
1768
1769         tpg = kzalloc(sizeof(struct scsiback_tpg), GFP_KERNEL);
1770         if (!tpg)
1771                 return ERR_PTR(-ENOMEM);
1772
1773         mutex_init(&tpg->tv_tpg_mutex);
1774         INIT_LIST_HEAD(&tpg->tv_tpg_list);
1775         INIT_LIST_HEAD(&tpg->info_list);
1776         tpg->tport = tport;
1777         tpg->tport_tpgt = tpgt;
1778
1779         ret = core_tpg_register(wwn, &tpg->se_tpg, tport->tport_proto_id);
1780         if (ret < 0) {
1781                 kfree(tpg);
1782                 return NULL;
1783         }
1784         mutex_lock(&scsiback_mutex);
1785         list_add_tail(&tpg->tv_tpg_list, &scsiback_list);
1786         mutex_unlock(&scsiback_mutex);
1787
1788         return &tpg->se_tpg;
1789 }
1790
1791 static void scsiback_drop_tpg(struct se_portal_group *se_tpg)
1792 {
1793         struct scsiback_tpg *tpg = container_of(se_tpg,
1794                                 struct scsiback_tpg, se_tpg);
1795
1796         mutex_lock(&scsiback_mutex);
1797         list_del(&tpg->tv_tpg_list);
1798         mutex_unlock(&scsiback_mutex);
1799         /*
1800          * Release the virtual I_T Nexus for this xen-pvscsi TPG
1801          */
1802         scsiback_drop_nexus(tpg);
1803         /*
1804          * Deregister the se_tpg from TCM.
1805          */
1806         core_tpg_deregister(se_tpg);
1807         kfree(tpg);
1808 }
1809
1810 static int scsiback_check_true(struct se_portal_group *se_tpg)
1811 {
1812         return 1;
1813 }
1814
1815 static int scsiback_check_false(struct se_portal_group *se_tpg)
1816 {
1817         return 0;
1818 }
1819
1820 static const struct target_core_fabric_ops scsiback_ops = {
1821         .module                         = THIS_MODULE,
1822         .name                           = "xen-pvscsi",
1823         .get_fabric_name                = scsiback_get_fabric_name,
1824         .tpg_get_wwn                    = scsiback_get_fabric_wwn,
1825         .tpg_get_tag                    = scsiback_get_tag,
1826         .tpg_check_demo_mode            = scsiback_check_true,
1827         .tpg_check_demo_mode_cache      = scsiback_check_true,
1828         .tpg_check_demo_mode_write_protect = scsiback_check_false,
1829         .tpg_check_prod_mode_write_protect = scsiback_check_false,
1830         .tpg_get_inst_index             = scsiback_tpg_get_inst_index,
1831         .check_stop_free                = scsiback_check_stop_free,
1832         .release_cmd                    = scsiback_release_cmd,
1833         .sess_get_index                 = scsiback_sess_get_index,
1834         .sess_get_initiator_sid         = NULL,
1835         .write_pending                  = scsiback_write_pending,
1836         .write_pending_status           = scsiback_write_pending_status,
1837         .set_default_node_attributes    = scsiback_set_default_node_attrs,
1838         .get_cmd_state                  = scsiback_get_cmd_state,
1839         .queue_data_in                  = scsiback_queue_data_in,
1840         .queue_status                   = scsiback_queue_status,
1841         .queue_tm_rsp                   = scsiback_queue_tm_rsp,
1842         .aborted_task                   = scsiback_aborted_task,
1843         /*
1844          * Setup callers for generic logic in target_core_fabric_configfs.c
1845          */
1846         .fabric_make_wwn                = scsiback_make_tport,
1847         .fabric_drop_wwn                = scsiback_drop_tport,
1848         .fabric_make_tpg                = scsiback_make_tpg,
1849         .fabric_drop_tpg                = scsiback_drop_tpg,
1850         .fabric_post_link               = scsiback_port_link,
1851         .fabric_pre_unlink              = scsiback_port_unlink,
1852
1853         .tfc_wwn_attrs                  = scsiback_wwn_attrs,
1854         .tfc_tpg_base_attrs             = scsiback_tpg_attrs,
1855         .tfc_tpg_param_attrs            = scsiback_param_attrs,
1856 };
1857
1858 static const struct xenbus_device_id scsiback_ids[] = {
1859         { "vscsi" },
1860         { "" }
1861 };
1862
1863 static struct xenbus_driver scsiback_driver = {
1864         .ids                    = scsiback_ids,
1865         .probe                  = scsiback_probe,
1866         .remove                 = scsiback_remove,
1867         .otherend_changed       = scsiback_frontend_changed
1868 };
1869
1870 static int __init scsiback_init(void)
1871 {
1872         int ret;
1873
1874         if (!xen_domain())
1875                 return -ENODEV;
1876
1877         pr_debug("xen-pvscsi: fabric module %s on %s/%s on "UTS_RELEASE"\n",
1878                  VSCSI_VERSION, utsname()->sysname, utsname()->machine);
1879
1880         ret = xenbus_register_backend(&scsiback_driver);
1881         if (ret)
1882                 goto out;
1883
1884         ret = target_register_template(&scsiback_ops);
1885         if (ret)
1886                 goto out_unregister_xenbus;
1887
1888         return 0;
1889
1890 out_unregister_xenbus:
1891         xenbus_unregister_driver(&scsiback_driver);
1892 out:
1893         pr_err("%s: error %d\n", __func__, ret);
1894         return ret;
1895 }
1896
1897 static void __exit scsiback_exit(void)
1898 {
1899         struct page *page;
1900
1901         while (free_pages_num) {
1902                 if (get_free_page(&page))
1903                         BUG();
1904                 gnttab_free_pages(1, &page);
1905         }
1906         target_unregister_template(&scsiback_ops);
1907         xenbus_unregister_driver(&scsiback_driver);
1908 }
1909
1910 module_init(scsiback_init);
1911 module_exit(scsiback_exit);
1912
1913 MODULE_DESCRIPTION("Xen SCSI backend driver");
1914 MODULE_LICENSE("Dual BSD/GPL");
1915 MODULE_ALIAS("xen-backend:vscsi");
1916 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");