drivers/scsi/virtio_scsi.c

   1 /*
   2  * Virtio SCSI HBA driver
   3  *
   4  * Copyright IBM Corp. 2010
   5  * Copyright Red Hat, Inc. 2011
   6  *
   7  * Authors:
   8  *  Stefan Hajnoczi   <stefanha@linux.vnet.ibm.com>
   9  *  Paolo Bonzini   <pbonzini@redhat.com>
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  12  * See the COPYING file in the top-level directory.
  13  *
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/slab.h>
  18 #include <linux/mempool.h>
  19 #include <linux/virtio.h>
  20 #include <linux/virtio_ids.h>
  21 #include <linux/virtio_config.h>
  22 #include <linux/virtio_scsi.h>
  23 #include <scsi/scsi_host.h>
  24 #include <scsi/scsi_device.h>
  25 #include <scsi/scsi_cmnd.h>
  26
  27 #define VIRTIO_SCSI_MEMPOOL_SZ 64
  28 #define VIRTIO_SCSI_EVENT_LEN 8
  29
  30 /* Command queue element */
  31 struct virtio_scsi_cmd {
  32         struct scsi_cmnd *sc;
  33         struct completion *comp;
  34         union {
  35                 struct virtio_scsi_cmd_req       cmd;
  36                 struct virtio_scsi_ctrl_tmf_req  tmf;
  37                 struct virtio_scsi_ctrl_an_req   an;
  38         } req;
  39         union {
  40                 struct virtio_scsi_cmd_resp      cmd;
  41                 struct virtio_scsi_ctrl_tmf_resp tmf;
  42                 struct virtio_scsi_ctrl_an_resp  an;
  43                 struct virtio_scsi_event         evt;
  44         } resp;
  45 } ____cacheline_aligned_in_smp;
  46
  47 struct virtio_scsi_event_node {
  48         struct virtio_scsi *vscsi;
  49         struct virtio_scsi_event event;
  50         struct work_struct work;
  51 };
  52
  53 struct virtio_scsi_vq {
  54         /* Protects vq */
  55         spinlock_t vq_lock;
  56
  57         struct virtqueue *vq;
  58 };
  59
  60 /* Per-target queue state */
  61 struct virtio_scsi_target_state {
  62         /* Protects sg.  Lock hierarchy is tgt_lock -> vq_lock.  */
  63         spinlock_t tgt_lock;
  64
  65         /* For sglist construction when adding commands to the virtqueue.  */
  66         struct scatterlist sg[];
  67 };
  68
  69 /* Driver instance state */
  70 struct virtio_scsi {
  71         struct virtio_device *vdev;
  72
  73         struct virtio_scsi_vq ctrl_vq;
  74         struct virtio_scsi_vq event_vq;
  75         struct virtio_scsi_vq req_vq;
  76
  77         /* Get some buffers ready for event vq */
  78         struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN];
  79
  80         struct virtio_scsi_target_state *tgt[];
  81 };
  82
  83 static struct kmem_cache *virtscsi_cmd_cache;
  84 static mempool_t *virtscsi_cmd_pool;
  85
  86 static inline struct Scsi_Host *virtio_scsi_host(struct virtio_device *vdev)
  87 {
  88         return vdev->priv;
  89 }
  90
  91 static void virtscsi_compute_resid(struct scsi_cmnd *sc, u32 resid)
  92 {
  93         if (!resid)
  94                 return;
  95
  96         if (!scsi_bidi_cmnd(sc)) {
  97                 scsi_set_resid(sc, resid);
  98                 return;
  99         }
 100
 101         scsi_in(sc)->resid = min(resid, scsi_in(sc)->length);
 102         scsi_out(sc)->resid = resid - scsi_in(sc)->resid;
 103 }
 104
 105 /**
 106  * virtscsi_complete_cmd - finish a scsi_cmd and invoke scsi_done
 107  *
 108  * Called with vq_lock held.
 109  */
 110 static void virtscsi_complete_cmd(void *buf)
 111 {
 112         struct virtio_scsi_cmd *cmd = buf;
 113         struct scsi_cmnd *sc = cmd->sc;
 114         struct virtio_scsi_cmd_resp *resp = &cmd->resp.cmd;
 115
 116         dev_dbg(&sc->device->sdev_gendev,
 117                 "cmd %p response %u status %#02x sense_len %u\n",
 118                 sc, resp->response, resp->status, resp->sense_len);
 119
 120         sc->result = resp->status;
 121         virtscsi_compute_resid(sc, resp->resid);
 122         switch (resp->response) {
 123         case VIRTIO_SCSI_S_OK:
 124                 set_host_byte(sc, DID_OK);
 125                 break;
 126         case VIRTIO_SCSI_S_OVERRUN:
 127                 set_host_byte(sc, DID_ERROR);
 128                 break;
 129         case VIRTIO_SCSI_S_ABORTED:
 130                 set_host_byte(sc, DID_ABORT);
 131                 break;
 132         case VIRTIO_SCSI_S_BAD_TARGET:
 133                 set_host_byte(sc, DID_BAD_TARGET);
 134                 break;
 135         case VIRTIO_SCSI_S_RESET:
 136                 set_host_byte(sc, DID_RESET);
 137                 break;
 138         case VIRTIO_SCSI_S_BUSY:
 139                 set_host_byte(sc, DID_BUS_BUSY);
 140                 break;
 141         case VIRTIO_SCSI_S_TRANSPORT_FAILURE:
 142                 set_host_byte(sc, DID_TRANSPORT_DISRUPTED);
 143                 break;
 144         case VIRTIO_SCSI_S_TARGET_FAILURE:
 145                 set_host_byte(sc, DID_TARGET_FAILURE);
 146                 break;
 147         case VIRTIO_SCSI_S_NEXUS_FAILURE:
 148                 set_host_byte(sc, DID_NEXUS_FAILURE);
 149                 break;
 150         default:
 151                 scmd_printk(KERN_WARNING, sc, "Unknown response %d",
 152                             resp->response);
 153                 /* fall through */
 154         case VIRTIO_SCSI_S_FAILURE:
 155                 set_host_byte(sc, DID_ERROR);
 156                 break;
 157         }
 158
 159         WARN_ON(resp->sense_len > VIRTIO_SCSI_SENSE_SIZE);
 160         if (sc->sense_buffer) {
 161                 memcpy(sc->sense_buffer, resp->sense,
 162                        min_t(u32, resp->sense_len, VIRTIO_SCSI_SENSE_SIZE));
 163                 if (resp->sense_len)
 164                         set_driver_byte(sc, DRIVER_SENSE);
 165         }
 166
 167         mempool_free(cmd, virtscsi_cmd_pool);
 168         sc->scsi_done(sc);
 169 }
 170
 171 static void virtscsi_vq_done(struct virtqueue *vq, void (*fn)(void *buf))
 172 {
 173         void *buf;
 174         unsigned int len;
 175
 176         do {
 177                 virtqueue_disable_cb(vq);
 178                 while ((buf = virtqueue_get_buf(vq, &len)) != NULL)
 179                         fn(buf);
 180         } while (!virtqueue_enable_cb(vq));
 181 }
 182
 183 static void virtscsi_req_done(struct virtqueue *vq)
 184 {
 185         struct Scsi_Host *sh = virtio_scsi_host(vq->vdev);
 186         struct virtio_scsi *vscsi = shost_priv(sh);
 187         unsigned long flags;
 188
 189         spin_lock_irqsave(&vscsi->req_vq.vq_lock, flags);
 190         virtscsi_vq_done(vq, virtscsi_complete_cmd);
 191         spin_unlock_irqrestore(&vscsi->req_vq.vq_lock, flags);
 192 };
 193
 194 static void virtscsi_complete_free(void *buf)
 195 {
 196         struct virtio_scsi_cmd *cmd = buf;
 197
 198         if (cmd->comp)
 199                 complete_all(cmd->comp);
 200         else
 201                 mempool_free(cmd, virtscsi_cmd_pool);
 202 }
 203
 204 static void virtscsi_ctrl_done(struct virtqueue *vq)
 205 {
 206         struct Scsi_Host *sh = virtio_scsi_host(vq->vdev);
 207         struct virtio_scsi *vscsi = shost_priv(sh);
 208         unsigned long flags;
 209
 210         spin_lock_irqsave(&vscsi->ctrl_vq.vq_lock, flags);
 211         virtscsi_vq_done(vq, virtscsi_complete_free);
 212         spin_unlock_irqrestore(&vscsi->ctrl_vq.vq_lock, flags);
 213 };
 214
 215 static int virtscsi_kick_event(struct virtio_scsi *vscsi,
 216                                struct virtio_scsi_event_node *event_node)
 217 {
 218         int err;
 219         struct scatterlist sg;
 220         unsigned long flags;
 221
 222         sg_init_one(&sg, &event_node->event, sizeof(struct virtio_scsi_event));
 223
 224         spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags);
 225
 226         err = virtqueue_add_buf(vscsi->event_vq.vq, &sg, 0, 1, event_node,
 227                                 GFP_ATOMIC);
 228         if (!err)
 229                 virtqueue_kick(vscsi->event_vq.vq);
 230
 231         spin_unlock_irqrestore(&vscsi->event_vq.vq_lock, flags);
 232
 233         return err;
 234 }
 235
 236 static int virtscsi_kick_event_all(struct virtio_scsi *vscsi)
 237 {
 238         int i;
 239
 240         for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++) {
 241                 vscsi->event_list[i].vscsi = vscsi;
 242                 virtscsi_kick_event(vscsi, &vscsi->event_list[i]);
 243         }
 244
 245         return 0;
 246 }
 247
 248 static void virtscsi_cancel_event_work(struct virtio_scsi *vscsi)
 249 {
 250         int i;
 251
 252         for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++)
 253                 cancel_work_sync(&vscsi->event_list[i].work);
 254 }
 255
 256 static void virtscsi_handle_transport_reset(struct virtio_scsi *vscsi,
 257                                                 struct virtio_scsi_event *event)
 258 {
 259         struct scsi_device *sdev;
 260         struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
 261         unsigned int target = event->lun[1];
 262         unsigned int lun = (event->lun[2] << 8) | event->lun[3];
 263
 264         switch (event->reason) {
 265         case VIRTIO_SCSI_EVT_RESET_RESCAN:
 266                 scsi_add_device(shost, 0, target, lun);
 267                 break;
 268         case VIRTIO_SCSI_EVT_RESET_REMOVED:
 269                 sdev = scsi_device_lookup(shost, 0, target, lun);
 270                 if (sdev) {
 271                         scsi_remove_device(sdev);
 272                         scsi_device_put(sdev);
 273                 } else {
 274                         pr_err("SCSI device %d 0 %d %d not found\n",
 275                                 shost->host_no, target, lun);
 276                 }
 277                 break;
 278         default:
 279                 pr_info("Unsupport virtio scsi event reason %x\n", event->reason);
 280         }
 281 }
 282
 283 static void virtscsi_handle_param_change(struct virtio_scsi *vscsi,
 284                                          struct virtio_scsi_event *event)
 285 {
 286         struct scsi_device *sdev;
 287         struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
 288         unsigned int target = event->lun[1];
 289         unsigned int lun = (event->lun[2] << 8) | event->lun[3];
 290         u8 asc = event->reason & 255;
 291         u8 ascq = event->reason >> 8;
 292
 293         sdev = scsi_device_lookup(shost, 0, target, lun);
 294         if (!sdev) {
 295                 pr_err("SCSI device %d 0 %d %d not found\n",
 296                         shost->host_no, target, lun);
 297                 return;
 298         }
 299
 300         /* Handle "Parameters changed", "Mode parameters changed", and
 301            "Capacity data has changed".  */
 302         if (asc == 0x2a && (ascq == 0x00 || ascq == 0x01 || ascq == 0x09))
 303                 scsi_rescan_device(&sdev->sdev_gendev);
 304
 305         scsi_device_put(sdev);
 306 }
 307
 308 static void virtscsi_handle_event(struct work_struct *work)
 309 {
 310         struct virtio_scsi_event_node *event_node =
 311                 container_of(work, struct virtio_scsi_event_node, work);
 312         struct virtio_scsi *vscsi = event_node->vscsi;
 313         struct virtio_scsi_event *event = &event_node->event;
 314
 315         if (event->event & VIRTIO_SCSI_T_EVENTS_MISSED) {
 316                 event->event &= ~VIRTIO_SCSI_T_EVENTS_MISSED;
 317                 scsi_scan_host(virtio_scsi_host(vscsi->vdev));
 318         }
 319
 320         switch (event->event) {
 321         case VIRTIO_SCSI_T_NO_EVENT:
 322                 break;
 323         case VIRTIO_SCSI_T_TRANSPORT_RESET:
 324                 virtscsi_handle_transport_reset(vscsi, event);
 325                 break;
 326         case VIRTIO_SCSI_T_PARAM_CHANGE:
 327                 virtscsi_handle_param_change(vscsi, event);
 328                 break;
 329         default:
 330                 pr_err("Unsupport virtio scsi event %x\n", event->event);
 331         }
 332         virtscsi_kick_event(vscsi, event_node);
 333 }
 334
 335 static void virtscsi_complete_event(void *buf)
 336 {
 337         struct virtio_scsi_event_node *event_node = buf;
 338
 339         INIT_WORK(&event_node->work, virtscsi_handle_event);
 340         schedule_work(&event_node->work);
 341 }
 342
 343 static void virtscsi_event_done(struct virtqueue *vq)
 344 {
 345         struct Scsi_Host *sh = virtio_scsi_host(vq->vdev);
 346         struct virtio_scsi *vscsi = shost_priv(sh);
 347         unsigned long flags;
 348
 349         spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags);
 350         virtscsi_vq_done(vq, virtscsi_complete_event);
 351         spin_unlock_irqrestore(&vscsi->event_vq.vq_lock, flags);
 352 };
 353
 354 static void virtscsi_map_sgl(struct scatterlist *sg, unsigned int *p_idx,
 355                              struct scsi_data_buffer *sdb)
 356 {
 357         struct sg_table *table = &sdb->table;
 358         struct scatterlist *sg_elem;
 359         unsigned int idx = *p_idx;
 360         int i;
 361
 362         for_each_sg(table->sgl, sg_elem, table->nents, i)
 363                 sg[idx++] = *sg_elem;
 364
 365         *p_idx = idx;
 366 }
 367
 368 /**
 369  * virtscsi_map_cmd - map a scsi_cmd to a virtqueue scatterlist
 370  * @vscsi       : virtio_scsi state
 371  * @cmd         : command structure
 372  * @out_num     : number of read-only elements
 373  * @in_num      : number of write-only elements
 374  * @req_size    : size of the request buffer
 375  * @resp_size   : size of the response buffer
 376  *
 377  * Called with tgt_lock held.
 378  */
 379 static void virtscsi_map_cmd(struct virtio_scsi_target_state *tgt,
 380                              struct virtio_scsi_cmd *cmd,
 381                              unsigned *out_num, unsigned *in_num,
 382                              size_t req_size, size_t resp_size)
 383 {
 384         struct scsi_cmnd *sc = cmd->sc;
 385         struct scatterlist *sg = tgt->sg;
 386         unsigned int idx = 0;
 387
 388         /* Request header.  */
 389         sg_set_buf(&sg[idx++], &cmd->req, req_size);
 390
 391         /* Data-out buffer.  */
 392         if (sc && sc->sc_data_direction != DMA_FROM_DEVICE)
 393                 virtscsi_map_sgl(sg, &idx, scsi_out(sc));
 394
 395         *out_num = idx;
 396
 397         /* Response header.  */
 398         sg_set_buf(&sg[idx++], &cmd->resp, resp_size);
 399
 400         /* Data-in buffer */
 401         if (sc && sc->sc_data_direction != DMA_TO_DEVICE)
 402                 virtscsi_map_sgl(sg, &idx, scsi_in(sc));
 403
 404         *in_num = idx - *out_num;
 405 }
 406
 407 static int virtscsi_kick_cmd(struct virtio_scsi_target_state *tgt,
 408                              struct virtio_scsi_vq *vq,
 409                              struct virtio_scsi_cmd *cmd,
 410                              size_t req_size, size_t resp_size, gfp_t gfp)
 411 {
 412         unsigned int out_num, in_num;
 413         unsigned long flags;
 414         int err;
 415         bool needs_kick = false;
 416
 417         spin_lock_irqsave(&tgt->tgt_lock, flags);
 418         virtscsi_map_cmd(tgt, cmd, &out_num, &in_num, req_size, resp_size);
 419
 420         spin_lock(&vq->vq_lock);
 421         err = virtqueue_add_buf(vq->vq, tgt->sg, out_num, in_num, cmd, gfp);
 422         spin_unlock(&tgt->tgt_lock);
 423         if (!err)
 424                 needs_kick = virtqueue_kick_prepare(vq->vq);
 425
 426         spin_unlock_irqrestore(&vq->vq_lock, flags);
 427
 428         if (needs_kick)
 429                 virtqueue_notify(vq->vq);
 430         return err;
 431 }
 432
 433 static int virtscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc)
 434 {
 435         struct virtio_scsi *vscsi = shost_priv(sh);
 436         struct virtio_scsi_target_state *tgt = vscsi->tgt[sc->device->id];
 437         struct virtio_scsi_cmd *cmd;
 438         int ret;
 439
 440         struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
 441         BUG_ON(scsi_sg_count(sc) > shost->sg_tablesize);
 442
 443         /* TODO: check feature bit and fail if unsupported?  */
 444         BUG_ON(sc->sc_data_direction == DMA_BIDIRECTIONAL);
 445
 446         dev_dbg(&sc->device->sdev_gendev,
 447                 "cmd %p CDB: %#02x\n", sc, sc->cmnd[0]);
 448
 449         ret = SCSI_MLQUEUE_HOST_BUSY;
 450         cmd = mempool_alloc(virtscsi_cmd_pool, GFP_ATOMIC);
 451         if (!cmd)
 452                 goto out;
 453
 454         memset(cmd, 0, sizeof(*cmd));
 455         cmd->sc = sc;
 456         cmd->req.cmd = (struct virtio_scsi_cmd_req){
 457                 .lun[0] = 1,
 458                 .lun[1] = sc->device->id,
 459                 .lun[2] = (sc->device->lun >> 8) | 0x40,
 460                 .lun[3] = sc->device->lun & 0xff,
 461                 .tag = (unsigned long)sc,
 462                 .task_attr = VIRTIO_SCSI_S_SIMPLE,
 463                 .prio = 0,
 464                 .crn = 0,
 465         };
 466
 467         BUG_ON(sc->cmd_len > VIRTIO_SCSI_CDB_SIZE);
 468         memcpy(cmd->req.cmd.cdb, sc->cmnd, sc->cmd_len);
 469
 470         if (virtscsi_kick_cmd(tgt, &vscsi->req_vq, cmd,
 471                               sizeof cmd->req.cmd, sizeof cmd->resp.cmd,
 472                               GFP_ATOMIC) == 0)
 473                 ret = 0;
 474         else
 475                 mempool_free(cmd, virtscsi_cmd_pool);
 476
 477 out:
 478         return ret;
 479 }
 480
 481 static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)
 482 {
 483         DECLARE_COMPLETION_ONSTACK(comp);
 484         struct virtio_scsi_target_state *tgt = vscsi->tgt[cmd->sc->device->id];
 485         int ret = FAILED;
 486
 487         cmd->comp = &comp;
 488         if (virtscsi_kick_cmd(tgt, &vscsi->ctrl_vq, cmd,
 489                               sizeof cmd->req.tmf, sizeof cmd->resp.tmf,
 490                               GFP_NOIO) < 0)
 491                 goto out;
 492
 493         wait_for_completion(&comp);
 494         if (cmd->resp.tmf.response == VIRTIO_SCSI_S_OK ||
 495             cmd->resp.tmf.response == VIRTIO_SCSI_S_FUNCTION_SUCCEEDED)
 496                 ret = SUCCESS;
 497
 498 out:
 499         mempool_free(cmd, virtscsi_cmd_pool);
 500         return ret;
 501 }
 502
 503 static int virtscsi_device_reset(struct scsi_cmnd *sc)
 504 {
 505         struct virtio_scsi *vscsi = shost_priv(sc->device->host);
 506         struct virtio_scsi_cmd *cmd;
 507
 508         sdev_printk(KERN_INFO, sc->device, "device reset\n");
 509         cmd = mempool_alloc(virtscsi_cmd_pool, GFP_NOIO);
 510         if (!cmd)
 511                 return FAILED;
 512
 513         memset(cmd, 0, sizeof(*cmd));
 514         cmd->sc = sc;
 515         cmd->req.tmf = (struct virtio_scsi_ctrl_tmf_req){
 516                 .type = VIRTIO_SCSI_T_TMF,
 517                 .subtype = VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET,
 518                 .lun[0] = 1,
 519                 .lun[1] = sc->device->id,
 520                 .lun[2] = (sc->device->lun >> 8) | 0x40,
 521                 .lun[3] = sc->device->lun & 0xff,
 522         };
 523         return virtscsi_tmf(vscsi, cmd);
 524 }
 525
 526 static int virtscsi_abort(struct scsi_cmnd *sc)
 527 {
 528         struct virtio_scsi *vscsi = shost_priv(sc->device->host);
 529         struct virtio_scsi_cmd *cmd;
 530
 531         scmd_printk(KERN_INFO, sc, "abort\n");
 532         cmd = mempool_alloc(virtscsi_cmd_pool, GFP_NOIO);
 533         if (!cmd)
 534                 return FAILED;
 535
 536         memset(cmd, 0, sizeof(*cmd));
 537         cmd->sc = sc;
 538         cmd->req.tmf = (struct virtio_scsi_ctrl_tmf_req){
 539                 .type = VIRTIO_SCSI_T_TMF,
 540                 .subtype = VIRTIO_SCSI_T_TMF_ABORT_TASK,
 541                 .lun[0] = 1,
 542                 .lun[1] = sc->device->id,
 543                 .lun[2] = (sc->device->lun >> 8) | 0x40,
 544                 .lun[3] = sc->device->lun & 0xff,
 545                 .tag = (unsigned long)sc,
 546         };
 547         return virtscsi_tmf(vscsi, cmd);
 548 }
 549
 550 static struct scsi_host_template virtscsi_host_template = {
 551         .module = THIS_MODULE,
 552         .name = "Virtio SCSI HBA",
 553         .proc_name = "virtio_scsi",
 554         .queuecommand = virtscsi_queuecommand,
 555         .this_id = -1,
 556         .eh_abort_handler = virtscsi_abort,
 557         .eh_device_reset_handler = virtscsi_device_reset,
 558
 559         .can_queue = 1024,
 560         .dma_boundary = UINT_MAX,
 561         .use_clustering = ENABLE_CLUSTERING,
 562 };
 563
 564 #define virtscsi_config_get(vdev, fld) \
 565         ({ \
 566                 typeof(((struct virtio_scsi_config *)0)->fld) __val; \
 567                 vdev->config->get(vdev, \
 568                                   offsetof(struct virtio_scsi_config, fld), \
 569                                   &__val, sizeof(__val)); \
 570                 __val; \
 571         })
 572
 573 #define virtscsi_config_set(vdev, fld, val) \
 574         (void)({ \
 575                 typeof(((struct virtio_scsi_config *)0)->fld) __val = (val); \
 576                 vdev->config->set(vdev, \
 577                                   offsetof(struct virtio_scsi_config, fld), \
 578                                   &__val, sizeof(__val)); \
 579         })
 580
 581 static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
 582                              struct virtqueue *vq)
 583 {
 584         spin_lock_init(&virtscsi_vq->vq_lock);
 585         virtscsi_vq->vq = vq;
 586 }
 587
 588 static struct virtio_scsi_target_state *virtscsi_alloc_tgt(
 589         struct virtio_device *vdev, int sg_elems)
 590 {
 591         struct virtio_scsi_target_state *tgt;
 592         gfp_t gfp_mask = GFP_KERNEL;
 593
 594         /* We need extra sg elements at head and tail.  */
 595         tgt = kmalloc(sizeof(*tgt) + sizeof(tgt->sg[0]) * (sg_elems + 2),
 596                       gfp_mask);
 597
 598         if (!tgt)
 599                 return NULL;
 600
 601         spin_lock_init(&tgt->tgt_lock);
 602         sg_init_table(tgt->sg, sg_elems + 2);
 603         return tgt;
 604 }
 605
 606 static void virtscsi_scan(struct virtio_device *vdev)
 607 {
 608         struct Scsi_Host *shost = (struct Scsi_Host *)vdev->priv;
 609
 610         scsi_scan_host(shost);
 611 }
 612
 613 static void virtscsi_remove_vqs(struct virtio_device *vdev)
 614 {
 615         struct Scsi_Host *sh = virtio_scsi_host(vdev);
 616         struct virtio_scsi *vscsi = shost_priv(sh);
 617         u32 i, num_targets;
 618
 619         /* Stop all the virtqueues. */
 620         vdev->config->reset(vdev);
 621
 622         num_targets = sh->max_id;
 623         for (i = 0; i < num_targets; i++) {
 624                 kfree(vscsi->tgt[i]);
 625                 vscsi->tgt[i] = NULL;
 626         }
 627
 628         vdev->config->del_vqs(vdev);
 629 }
 630
 631 static int virtscsi_init(struct virtio_device *vdev,
 632                          struct virtio_scsi *vscsi, int num_targets)
 633 {
 634         int err;
 635         struct virtqueue *vqs[3];
 636         u32 i, sg_elems;
 637
 638         vq_callback_t *callbacks[] = {
 639                 virtscsi_ctrl_done,
 640                 virtscsi_event_done,
 641                 virtscsi_req_done
 642         };
 643         const char *names[] = {
 644                 "control",
 645                 "event",
 646                 "request"
 647         };
 648
 649         /* Discover virtqueues and write information to configuration.  */
 650         err = vdev->config->find_vqs(vdev, 3, vqs, callbacks, names);
 651         if (err)
 652                 return err;
 653
 654         virtscsi_init_vq(&vscsi->ctrl_vq, vqs[0]);
 655         virtscsi_init_vq(&vscsi->event_vq, vqs[1]);
 656         virtscsi_init_vq(&vscsi->req_vq, vqs[2]);
 657
 658         virtscsi_config_set(vdev, cdb_size, VIRTIO_SCSI_CDB_SIZE);
 659         virtscsi_config_set(vdev, sense_size, VIRTIO_SCSI_SENSE_SIZE);
 660
 661         if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
 662                 virtscsi_kick_event_all(vscsi);
 663
 664         /* We need to know how many segments before we allocate.  */
 665         sg_elems = virtscsi_config_get(vdev, seg_max) ?: 1;
 666
 667         for (i = 0; i < num_targets; i++) {
 668                 vscsi->tgt[i] = virtscsi_alloc_tgt(vdev, sg_elems);
 669                 if (!vscsi->tgt[i]) {
 670                         err = -ENOMEM;
 671                         goto out;
 672                 }
 673         }
 674         err = 0;
 675
 676 out:
 677         if (err)
 678                 virtscsi_remove_vqs(vdev);
 679         return err;
 680 }
 681
 682 static int __devinit virtscsi_probe(struct virtio_device *vdev)
 683 {
 684         struct Scsi_Host *shost;
 685         struct virtio_scsi *vscsi;
 686         int err;
 687         u32 sg_elems, num_targets;
 688         u32 cmd_per_lun;
 689
 690         /* Allocate memory and link the structs together.  */
 691         num_targets = virtscsi_config_get(vdev, max_target) + 1;
 692         shost = scsi_host_alloc(&virtscsi_host_template,
 693                 sizeof(*vscsi)
 694                 + num_targets * sizeof(struct virtio_scsi_target_state));
 695
 696         if (!shost)
 697                 return -ENOMEM;
 698
 699         sg_elems = virtscsi_config_get(vdev, seg_max) ?: 1;
 700         shost->sg_tablesize = sg_elems;
 701         vscsi = shost_priv(shost);
 702         vscsi->vdev = vdev;
 703         vdev->priv = shost;
 704
 705         err = virtscsi_init(vdev, vscsi, num_targets);
 706         if (err)
 707                 goto virtscsi_init_failed;
 708
 709         cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1;
 710         shost->cmd_per_lun = min_t(u32, cmd_per_lun, shost->can_queue);
 711         shost->max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0xFFFF;
 712
 713         /* LUNs > 256 are reported with format 1, so they go in the range
 714          * 16640-32767.
 715          */
 716         shost->max_lun = virtscsi_config_get(vdev, max_lun) + 1 + 0x4000;
 717         shost->max_id = num_targets;
 718         shost->max_channel = 0;
 719         shost->max_cmd_len = VIRTIO_SCSI_CDB_SIZE;
 720         err = scsi_add_host(shost, &vdev->dev);
 721         if (err)
 722                 goto scsi_add_host_failed;
 723         /*
 724          * scsi_scan_host() happens in virtscsi_scan() via virtio_driver->scan()
 725          * after VIRTIO_CONFIG_S_DRIVER_OK has been set..
 726          */
 727         return 0;
 728
 729 scsi_add_host_failed:
 730         vdev->config->del_vqs(vdev);
 731 virtscsi_init_failed:
 732         scsi_host_put(shost);
 733         return err;
 734 }
 735
 736 static void __devexit virtscsi_remove(struct virtio_device *vdev)
 737 {
 738         struct Scsi_Host *shost = virtio_scsi_host(vdev);
 739         struct virtio_scsi *vscsi = shost_priv(shost);
 740
 741         if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
 742                 virtscsi_cancel_event_work(vscsi);
 743
 744         scsi_remove_host(shost);
 745
 746         virtscsi_remove_vqs(vdev);
 747         scsi_host_put(shost);
 748 }
 749
 750 #ifdef CONFIG_PM
 751 static int virtscsi_freeze(struct virtio_device *vdev)
 752 {
 753         virtscsi_remove_vqs(vdev);
 754         return 0;
 755 }
 756
 757 static int virtscsi_restore(struct virtio_device *vdev)
 758 {
 759         struct Scsi_Host *sh = virtio_scsi_host(vdev);
 760         struct virtio_scsi *vscsi = shost_priv(sh);
 761
 762         return virtscsi_init(vdev, vscsi, sh->max_id);
 763 }
 764 #endif
 765
 766 static struct virtio_device_id id_table[] = {
 767         { VIRTIO_ID_SCSI, VIRTIO_DEV_ANY_ID },
 768         { 0 },
 769 };
 770
 771 static unsigned int features[] = {
 772         VIRTIO_SCSI_F_HOTPLUG,
 773         VIRTIO_SCSI_F_CHANGE,
 774 };
 775
 776 static struct virtio_driver virtio_scsi_driver = {
 777         .feature_table = features,
 778         .feature_table_size = ARRAY_SIZE(features),
 779         .driver.name = KBUILD_MODNAME,
 780         .driver.owner = THIS_MODULE,
 781         .id_table = id_table,
 782         .probe = virtscsi_probe,
 783         .scan = virtscsi_scan,
 784 #ifdef CONFIG_PM
 785         .freeze = virtscsi_freeze,
 786         .restore = virtscsi_restore,
 787 #endif
 788         .remove = __devexit_p(virtscsi_remove),
 789 };
 790
 791 static int __init init(void)
 792 {
 793         int ret = -ENOMEM;
 794
 795         virtscsi_cmd_cache = KMEM_CACHE(virtio_scsi_cmd, 0);
 796         if (!virtscsi_cmd_cache) {
 797                 printk(KERN_ERR "kmem_cache_create() for "
 798                                 "virtscsi_cmd_cache failed\n");
 799                 goto error;
 800         }
 801
 802
 803         virtscsi_cmd_pool =
 804                 mempool_create_slab_pool(VIRTIO_SCSI_MEMPOOL_SZ,
 805                                          virtscsi_cmd_cache);
 806         if (!virtscsi_cmd_pool) {
 807                 printk(KERN_ERR "mempool_create() for"
 808                                 "virtscsi_cmd_pool failed\n");
 809                 goto error;
 810         }
 811         ret = register_virtio_driver(&virtio_scsi_driver);
 812         if (ret < 0)
 813                 goto error;
 814
 815         return 0;
 816
 817 error:
 818         if (virtscsi_cmd_pool) {
 819                 mempool_destroy(virtscsi_cmd_pool);
 820                 virtscsi_cmd_pool = NULL;
 821         }
 822         if (virtscsi_cmd_cache) {
 823                 kmem_cache_destroy(virtscsi_cmd_cache);
 824                 virtscsi_cmd_cache = NULL;
 825         }
 826         return ret;
 827 }
 828
 829 static void __exit fini(void)
 830 {
 831         unregister_virtio_driver(&virtio_scsi_driver);
 832         mempool_destroy(virtscsi_cmd_pool);
 833         kmem_cache_destroy(virtscsi_cmd_cache);
 834 }
 835 module_init(init);
 836 module_exit(fini);
 837
 838 MODULE_DEVICE_TABLE(virtio, id_table);
 839 MODULE_DESCRIPTION("Virtio SCSI HBA driver");
 840 MODULE_LICENSE("GPL");