1 /* 2 * Xen SCSI frontend driver 3 * 4 * Copyright (c) 2008, FUJITSU Limited 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License version 2 8 * as published by the Free Software Foundation; or, when distributed 9 * separately from the Linux kernel or incorporated into other 10 * software packages, subject to the following license: 11 * 12 * Permission is hereby granted, free of charge, to any person obtaining a copy 13 * of this source file (the "Software"), to deal in the Software without 14 * restriction, including without limitation the rights to use, copy, modify, 15 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 16 * and to permit persons to whom the Software is furnished to do so, subject to 17 * the following conditions: 18 * 19 * The above copyright notice and this permission notice shall be included in 20 * all copies or substantial portions of the Software. 21 * 22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 27 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 28 * IN THE SOFTWARE. 29 */ 30 31 #include <linux/module.h> 32 #include <linux/kernel.h> 33 #include <linux/device.h> 34 #include <linux/wait.h> 35 #include <linux/interrupt.h> 36 #include <linux/mutex.h> 37 #include <linux/spinlock.h> 38 #include <linux/sched.h> 39 #include <linux/blkdev.h> 40 #include <linux/pfn.h> 41 #include <linux/slab.h> 42 #include <linux/bitops.h> 43 44 #include <scsi/scsi_cmnd.h> 45 #include <scsi/scsi_device.h> 46 #include <scsi/scsi.h> 47 #include <scsi/scsi_host.h> 48 49 #include <xen/xen.h> 50 #include <xen/xenbus.h> 51 #include <xen/grant_table.h> 52 #include <xen/events.h> 53 #include <xen/page.h> 54 55 #include <xen/interface/grant_table.h> 56 #include <xen/interface/io/vscsiif.h> 57 #include <xen/interface/io/protocols.h> 58 59 #include <asm/xen/hypervisor.h> 60 61 62 #define GRANT_INVALID_REF 0 63 64 #define VSCSIFRONT_OP_ADD_LUN 1 65 #define VSCSIFRONT_OP_DEL_LUN 2 66 #define VSCSIFRONT_OP_READD_LUN 3 67 68 /* Tuning point. */ 69 #define VSCSIIF_DEFAULT_CMD_PER_LUN 10 70 #define VSCSIIF_MAX_TARGET 64 71 #define VSCSIIF_MAX_LUN 255 72 73 #define VSCSIIF_RING_SIZE __CONST_RING_SIZE(vscsiif, PAGE_SIZE) 74 #define VSCSIIF_MAX_REQS VSCSIIF_RING_SIZE 75 76 #define vscsiif_grants_sg(_sg) (PFN_UP((_sg) * \ 77 sizeof(struct scsiif_request_segment))) 78 79 struct vscsifrnt_shadow { 80 /* command between backend and frontend */ 81 unsigned char act; 82 uint8_t nr_segments; 83 uint16_t rqid; 84 uint16_t ref_rqid; 85 86 unsigned int nr_grants; /* number of grants in gref[] */ 87 struct scsiif_request_segment *sg; /* scatter/gather elements */ 88 struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE]; 89 90 /* Do reset or abort function. */ 91 wait_queue_head_t wq_reset; /* reset work queue */ 92 int wait_reset; /* reset work queue condition */ 93 int32_t rslt_reset; /* reset response status: */ 94 /* SUCCESS or FAILED or: */ 95 #define RSLT_RESET_WAITING 0 96 #define RSLT_RESET_ERR -1 97 98 /* Requested struct scsi_cmnd is stored from kernel. */ 99 struct scsi_cmnd *sc; 100 int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL]; 101 }; 102 103 struct vscsifrnt_info { 104 struct xenbus_device *dev; 105 106 struct Scsi_Host *host; 107 int host_active; 108 109 unsigned int evtchn; 110 unsigned int irq; 111 112 grant_ref_t ring_ref; 113 struct vscsiif_front_ring ring; 114 struct vscsiif_response ring_rsp; 115 116 spinlock_t shadow_lock; 117 DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS); 118 struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS]; 119 120 /* Following items are protected by the host lock. */ 121 wait_queue_head_t wq_sync; 122 wait_queue_head_t wq_pause; 123 unsigned int wait_ring_available:1; 124 unsigned int waiting_pause:1; 125 unsigned int pause:1; 126 unsigned callers; 127 128 char dev_state_path[64]; 129 struct task_struct *curr; 130 }; 131 132 static DEFINE_MUTEX(scsifront_mutex); 133 134 static void scsifront_wake_up(struct vscsifrnt_info *info) 135 { 136 info->wait_ring_available = 0; 137 wake_up(&info->wq_sync); 138 } 139 140 static int scsifront_get_rqid(struct vscsifrnt_info *info) 141 { 142 unsigned long flags; 143 int free; 144 145 spin_lock_irqsave(&info->shadow_lock, flags); 146 147 free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); 148 __clear_bit(free, info->shadow_free_bitmap); 149 150 spin_unlock_irqrestore(&info->shadow_lock, flags); 151 152 return free; 153 } 154 155 static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id) 156 { 157 int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); 158 159 __set_bit(id, info->shadow_free_bitmap); 160 info->shadow[id] = NULL; 161 162 return empty || info->wait_ring_available; 163 } 164 165 static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id) 166 { 167 unsigned long flags; 168 int kick; 169 170 spin_lock_irqsave(&info->shadow_lock, flags); 171 kick = _scsifront_put_rqid(info, id); 172 spin_unlock_irqrestore(&info->shadow_lock, flags); 173 174 if (kick) 175 scsifront_wake_up(info); 176 } 177 178 static int scsifront_do_request(struct vscsifrnt_info *info, 179 struct vscsifrnt_shadow *shadow) 180 { 181 struct vscsiif_front_ring *ring = &(info->ring); 182 struct vscsiif_request *ring_req; 183 struct scsi_cmnd *sc = shadow->sc; 184 uint32_t id; 185 int i, notify; 186 187 if (RING_FULL(&info->ring)) 188 return -EBUSY; 189 190 id = scsifront_get_rqid(info); /* use id in response */ 191 if (id >= VSCSIIF_MAX_REQS) 192 return -EBUSY; 193 194 info->shadow[id] = shadow; 195 shadow->rqid = id; 196 197 ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt); 198 ring->req_prod_pvt++; 199 200 ring_req->rqid = id; 201 ring_req->act = shadow->act; 202 ring_req->ref_rqid = shadow->ref_rqid; 203 ring_req->nr_segments = shadow->nr_segments; 204 205 ring_req->id = sc->device->id; 206 ring_req->lun = sc->device->lun; 207 ring_req->channel = sc->device->channel; 208 ring_req->cmd_len = sc->cmd_len; 209 210 BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE); 211 212 memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len); 213 214 ring_req->sc_data_direction = (uint8_t)sc->sc_data_direction; 215 ring_req->timeout_per_command = sc->request->timeout / HZ; 216 217 for (i = 0; i < (shadow->nr_segments & ~VSCSIIF_SG_GRANT); i++) 218 ring_req->seg[i] = shadow->seg[i]; 219 220 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify); 221 if (notify) 222 notify_remote_via_irq(info->irq); 223 224 return 0; 225 } 226 227 static void scsifront_gnttab_done(struct vscsifrnt_info *info, 228 struct vscsifrnt_shadow *shadow) 229 { 230 int i; 231 232 if (shadow->sc->sc_data_direction == DMA_NONE) 233 return; 234 235 for (i = 0; i < shadow->nr_grants; i++) { 236 if (unlikely(gnttab_query_foreign_access(shadow->gref[i]))) { 237 shost_printk(KERN_ALERT, info->host, KBUILD_MODNAME 238 "grant still in use by backend\n"); 239 BUG(); 240 } 241 gnttab_end_foreign_access(shadow->gref[i], 0, 0UL); 242 } 243 244 kfree(shadow->sg); 245 } 246 247 static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info, 248 struct vscsiif_response *ring_rsp) 249 { 250 struct vscsifrnt_shadow *shadow; 251 struct scsi_cmnd *sc; 252 uint32_t id; 253 uint8_t sense_len; 254 255 id = ring_rsp->rqid; 256 shadow = info->shadow[id]; 257 sc = shadow->sc; 258 259 BUG_ON(sc == NULL); 260 261 scsifront_gnttab_done(info, shadow); 262 scsifront_put_rqid(info, id); 263 264 sc->result = ring_rsp->rslt; 265 scsi_set_resid(sc, ring_rsp->residual_len); 266 267 sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE, 268 ring_rsp->sense_len); 269 270 if (sense_len) 271 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len); 272 273 sc->scsi_done(sc); 274 } 275 276 static void scsifront_sync_cmd_done(struct vscsifrnt_info *info, 277 struct vscsiif_response *ring_rsp) 278 { 279 uint16_t id = ring_rsp->rqid; 280 unsigned long flags; 281 struct vscsifrnt_shadow *shadow = info->shadow[id]; 282 int kick; 283 284 spin_lock_irqsave(&info->shadow_lock, flags); 285 shadow->wait_reset = 1; 286 switch (shadow->rslt_reset) { 287 case RSLT_RESET_WAITING: 288 shadow->rslt_reset = ring_rsp->rslt; 289 break; 290 case RSLT_RESET_ERR: 291 kick = _scsifront_put_rqid(info, id); 292 spin_unlock_irqrestore(&info->shadow_lock, flags); 293 kfree(shadow); 294 if (kick) 295 scsifront_wake_up(info); 296 return; 297 default: 298 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME 299 "bad reset state %d, possibly leaking %u\n", 300 shadow->rslt_reset, id); 301 break; 302 } 303 spin_unlock_irqrestore(&info->shadow_lock, flags); 304 305 wake_up(&shadow->wq_reset); 306 } 307 308 static void scsifront_do_response(struct vscsifrnt_info *info, 309 struct vscsiif_response *ring_rsp) 310 { 311 if (WARN(ring_rsp->rqid >= VSCSIIF_MAX_REQS || 312 test_bit(ring_rsp->rqid, info->shadow_free_bitmap), 313 "illegal rqid %u returned by backend!\n", ring_rsp->rqid)) 314 return; 315 316 if (info->shadow[ring_rsp->rqid]->act == VSCSIIF_ACT_SCSI_CDB) 317 scsifront_cdb_cmd_done(info, ring_rsp); 318 else 319 scsifront_sync_cmd_done(info, ring_rsp); 320 } 321 322 static int scsifront_ring_drain(struct vscsifrnt_info *info) 323 { 324 struct vscsiif_response *ring_rsp; 325 RING_IDX i, rp; 326 int more_to_do = 0; 327 328 rp = info->ring.sring->rsp_prod; 329 rmb(); /* ordering required respective to dom0 */ 330 for (i = info->ring.rsp_cons; i != rp; i++) { 331 ring_rsp = RING_GET_RESPONSE(&info->ring, i); 332 scsifront_do_response(info, ring_rsp); 333 } 334 335 info->ring.rsp_cons = i; 336 337 if (i != info->ring.req_prod_pvt) 338 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); 339 else 340 info->ring.sring->rsp_event = i + 1; 341 342 return more_to_do; 343 } 344 345 static int scsifront_cmd_done(struct vscsifrnt_info *info) 346 { 347 int more_to_do; 348 unsigned long flags; 349 350 spin_lock_irqsave(info->host->host_lock, flags); 351 352 more_to_do = scsifront_ring_drain(info); 353 354 info->wait_ring_available = 0; 355 356 spin_unlock_irqrestore(info->host->host_lock, flags); 357 358 wake_up(&info->wq_sync); 359 360 return more_to_do; 361 } 362 363 static irqreturn_t scsifront_irq_fn(int irq, void *dev_id) 364 { 365 struct vscsifrnt_info *info = dev_id; 366 367 while (scsifront_cmd_done(info)) 368 /* Yield point for this unbounded loop. */ 369 cond_resched(); 370 371 return IRQ_HANDLED; 372 } 373 374 static void scsifront_finish_all(struct vscsifrnt_info *info) 375 { 376 unsigned i; 377 struct vscsiif_response resp; 378 379 scsifront_ring_drain(info); 380 381 for (i = 0; i < VSCSIIF_MAX_REQS; i++) { 382 if (test_bit(i, info->shadow_free_bitmap)) 383 continue; 384 resp.rqid = i; 385 resp.sense_len = 0; 386 resp.rslt = DID_RESET << 16; 387 resp.residual_len = 0; 388 scsifront_do_response(info, &resp); 389 } 390 } 391 392 static int map_data_for_request(struct vscsifrnt_info *info, 393 struct scsi_cmnd *sc, 394 struct vscsifrnt_shadow *shadow) 395 { 396 grant_ref_t gref_head; 397 struct page *page; 398 int err, ref, ref_cnt = 0; 399 int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE); 400 unsigned int i, off, len, bytes; 401 unsigned int data_len = scsi_bufflen(sc); 402 unsigned int data_grants = 0, seg_grants = 0; 403 struct scatterlist *sg; 404 struct scsiif_request_segment *seg; 405 406 if (sc->sc_data_direction == DMA_NONE || !data_len) 407 return 0; 408 409 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) 410 data_grants += PFN_UP(sg->offset + sg->length); 411 412 if (data_grants > VSCSIIF_SG_TABLESIZE) { 413 if (data_grants > info->host->sg_tablesize) { 414 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME 415 "Unable to map request_buffer for command!\n"); 416 return -E2BIG; 417 } 418 seg_grants = vscsiif_grants_sg(data_grants); 419 shadow->sg = kcalloc(data_grants, 420 sizeof(struct scsiif_request_segment), GFP_ATOMIC); 421 if (!shadow->sg) 422 return -ENOMEM; 423 } 424 seg = shadow->sg ? : shadow->seg; 425 426 err = gnttab_alloc_grant_references(seg_grants + data_grants, 427 &gref_head); 428 if (err) { 429 kfree(shadow->sg); 430 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME 431 "gnttab_alloc_grant_references() error\n"); 432 return -ENOMEM; 433 } 434 435 if (seg_grants) { 436 page = virt_to_page(seg); 437 off = offset_in_page(seg); 438 len = sizeof(struct scsiif_request_segment) * data_grants; 439 while (len > 0) { 440 bytes = min_t(unsigned int, len, PAGE_SIZE - off); 441 442 ref = gnttab_claim_grant_reference(&gref_head); 443 BUG_ON(ref == -ENOSPC); 444 445 gnttab_grant_foreign_access_ref(ref, 446 info->dev->otherend_id, 447 xen_page_to_gfn(page), 1); 448 shadow->gref[ref_cnt] = ref; 449 shadow->seg[ref_cnt].gref = ref; 450 shadow->seg[ref_cnt].offset = (uint16_t)off; 451 shadow->seg[ref_cnt].length = (uint16_t)bytes; 452 453 page++; 454 len -= bytes; 455 off = 0; 456 ref_cnt++; 457 } 458 BUG_ON(seg_grants < ref_cnt); 459 seg_grants = ref_cnt; 460 } 461 462 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) { 463 page = sg_page(sg); 464 off = sg->offset; 465 len = sg->length; 466 467 while (len > 0 && data_len > 0) { 468 /* 469 * sg sends a scatterlist that is larger than 470 * the data_len it wants transferred for certain 471 * IO sizes. 472 */ 473 bytes = min_t(unsigned int, len, PAGE_SIZE - off); 474 bytes = min(bytes, data_len); 475 476 ref = gnttab_claim_grant_reference(&gref_head); 477 BUG_ON(ref == -ENOSPC); 478 479 gnttab_grant_foreign_access_ref(ref, 480 info->dev->otherend_id, 481 xen_page_to_gfn(page), 482 grant_ro); 483 484 shadow->gref[ref_cnt] = ref; 485 seg->gref = ref; 486 seg->offset = (uint16_t)off; 487 seg->length = (uint16_t)bytes; 488 489 page++; 490 seg++; 491 len -= bytes; 492 data_len -= bytes; 493 off = 0; 494 ref_cnt++; 495 } 496 } 497 498 if (seg_grants) 499 shadow->nr_segments = VSCSIIF_SG_GRANT | seg_grants; 500 else 501 shadow->nr_segments = (uint8_t)ref_cnt; 502 shadow->nr_grants = ref_cnt; 503 504 return 0; 505 } 506 507 static int scsifront_enter(struct vscsifrnt_info *info) 508 { 509 if (info->pause) 510 return 1; 511 info->callers++; 512 return 0; 513 } 514 515 static void scsifront_return(struct vscsifrnt_info *info) 516 { 517 info->callers--; 518 if (info->callers) 519 return; 520 521 if (!info->waiting_pause) 522 return; 523 524 info->waiting_pause = 0; 525 wake_up(&info->wq_pause); 526 } 527 528 static int scsifront_queuecommand(struct Scsi_Host *shost, 529 struct scsi_cmnd *sc) 530 { 531 struct vscsifrnt_info *info = shost_priv(shost); 532 struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc); 533 unsigned long flags; 534 int err; 535 536 sc->result = 0; 537 538 shadow->sc = sc; 539 shadow->act = VSCSIIF_ACT_SCSI_CDB; 540 541 spin_lock_irqsave(shost->host_lock, flags); 542 if (scsifront_enter(info)) { 543 spin_unlock_irqrestore(shost->host_lock, flags); 544 return SCSI_MLQUEUE_HOST_BUSY; 545 } 546 547 err = map_data_for_request(info, sc, shadow); 548 if (err < 0) { 549 pr_debug("%s: err %d\n", __func__, err); 550 scsifront_return(info); 551 spin_unlock_irqrestore(shost->host_lock, flags); 552 if (err == -ENOMEM) 553 return SCSI_MLQUEUE_HOST_BUSY; 554 sc->result = DID_ERROR << 16; 555 sc->scsi_done(sc); 556 return 0; 557 } 558 559 if (scsifront_do_request(info, shadow)) { 560 scsifront_gnttab_done(info, shadow); 561 goto busy; 562 } 563 564 scsifront_return(info); 565 spin_unlock_irqrestore(shost->host_lock, flags); 566 567 return 0; 568 569 busy: 570 scsifront_return(info); 571 spin_unlock_irqrestore(shost->host_lock, flags); 572 pr_debug("%s: busy\n", __func__); 573 return SCSI_MLQUEUE_HOST_BUSY; 574 } 575 576 /* 577 * Any exception handling (reset or abort) must be forwarded to the backend. 578 * We have to wait until an answer is returned. This answer contains the 579 * result to be returned to the requestor. 580 */ 581 static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act) 582 { 583 struct Scsi_Host *host = sc->device->host; 584 struct vscsifrnt_info *info = shost_priv(host); 585 struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc); 586 int err = 0; 587 588 shadow = kzalloc(sizeof(*shadow), GFP_NOIO); 589 if (!shadow) 590 return FAILED; 591 592 shadow->act = act; 593 shadow->rslt_reset = RSLT_RESET_WAITING; 594 shadow->sc = sc; 595 shadow->ref_rqid = s->rqid; 596 init_waitqueue_head(&shadow->wq_reset); 597 598 spin_lock_irq(host->host_lock); 599 600 for (;;) { 601 if (scsifront_enter(info)) 602 goto fail; 603 604 if (!scsifront_do_request(info, shadow)) 605 break; 606 607 scsifront_return(info); 608 if (err) 609 goto fail; 610 info->wait_ring_available = 1; 611 spin_unlock_irq(host->host_lock); 612 err = wait_event_interruptible(info->wq_sync, 613 !info->wait_ring_available); 614 spin_lock_irq(host->host_lock); 615 } 616 617 spin_unlock_irq(host->host_lock); 618 err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset); 619 spin_lock_irq(host->host_lock); 620 621 if (!err) { 622 err = shadow->rslt_reset; 623 scsifront_put_rqid(info, shadow->rqid); 624 kfree(shadow); 625 } else { 626 spin_lock(&info->shadow_lock); 627 shadow->rslt_reset = RSLT_RESET_ERR; 628 spin_unlock(&info->shadow_lock); 629 err = FAILED; 630 } 631 632 scsifront_return(info); 633 spin_unlock_irq(host->host_lock); 634 return err; 635 636 fail: 637 spin_unlock_irq(host->host_lock); 638 kfree(shadow); 639 return FAILED; 640 } 641 642 static int scsifront_eh_abort_handler(struct scsi_cmnd *sc) 643 { 644 pr_debug("%s\n", __func__); 645 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT); 646 } 647 648 static int scsifront_dev_reset_handler(struct scsi_cmnd *sc) 649 { 650 pr_debug("%s\n", __func__); 651 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET); 652 } 653 654 static int scsifront_sdev_configure(struct scsi_device *sdev) 655 { 656 struct vscsifrnt_info *info = shost_priv(sdev->host); 657 int err; 658 659 if (info && current == info->curr) { 660 err = xenbus_printf(XBT_NIL, info->dev->nodename, 661 info->dev_state_path, "%d", XenbusStateConnected); 662 if (err) { 663 xenbus_dev_error(info->dev, err, 664 "%s: writing dev_state_path", __func__); 665 return err; 666 } 667 } 668 669 return 0; 670 } 671 672 static void scsifront_sdev_destroy(struct scsi_device *sdev) 673 { 674 struct vscsifrnt_info *info = shost_priv(sdev->host); 675 int err; 676 677 if (info && current == info->curr) { 678 err = xenbus_printf(XBT_NIL, info->dev->nodename, 679 info->dev_state_path, "%d", XenbusStateClosed); 680 if (err) 681 xenbus_dev_error(info->dev, err, 682 "%s: writing dev_state_path", __func__); 683 } 684 } 685 686 static struct scsi_host_template scsifront_sht = { 687 .module = THIS_MODULE, 688 .name = "Xen SCSI frontend driver", 689 .queuecommand = scsifront_queuecommand, 690 .eh_abort_handler = scsifront_eh_abort_handler, 691 .eh_device_reset_handler = scsifront_dev_reset_handler, 692 .slave_configure = scsifront_sdev_configure, 693 .slave_destroy = scsifront_sdev_destroy, 694 .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN, 695 .can_queue = VSCSIIF_MAX_REQS, 696 .this_id = -1, 697 .cmd_size = sizeof(struct vscsifrnt_shadow), 698 .sg_tablesize = VSCSIIF_SG_TABLESIZE, 699 .proc_name = "scsifront", 700 }; 701 702 static int scsifront_alloc_ring(struct vscsifrnt_info *info) 703 { 704 struct xenbus_device *dev = info->dev; 705 struct vscsiif_sring *sring; 706 grant_ref_t gref; 707 int err = -ENOMEM; 708 709 /***** Frontend to Backend ring start *****/ 710 sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL); 711 if (!sring) { 712 xenbus_dev_fatal(dev, err, 713 "fail to allocate shared ring (Front to Back)"); 714 return err; 715 } 716 SHARED_RING_INIT(sring); 717 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); 718 719 err = xenbus_grant_ring(dev, sring, 1, &gref); 720 if (err < 0) { 721 free_page((unsigned long)sring); 722 xenbus_dev_fatal(dev, err, 723 "fail to grant shared ring (Front to Back)"); 724 return err; 725 } 726 info->ring_ref = gref; 727 728 err = xenbus_alloc_evtchn(dev, &info->evtchn); 729 if (err) { 730 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn"); 731 goto free_gnttab; 732 } 733 734 err = bind_evtchn_to_irq(info->evtchn); 735 if (err <= 0) { 736 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq"); 737 goto free_gnttab; 738 } 739 740 info->irq = err; 741 742 err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn, 743 IRQF_ONESHOT, "scsifront", info); 744 if (err) { 745 xenbus_dev_fatal(dev, err, "request_threaded_irq"); 746 goto free_irq; 747 } 748 749 return 0; 750 751 /* free resource */ 752 free_irq: 753 unbind_from_irqhandler(info->irq, info); 754 free_gnttab: 755 gnttab_end_foreign_access(info->ring_ref, 0, 756 (unsigned long)info->ring.sring); 757 758 return err; 759 } 760 761 static void scsifront_free_ring(struct vscsifrnt_info *info) 762 { 763 unbind_from_irqhandler(info->irq, info); 764 gnttab_end_foreign_access(info->ring_ref, 0, 765 (unsigned long)info->ring.sring); 766 } 767 768 static int scsifront_init_ring(struct vscsifrnt_info *info) 769 { 770 struct xenbus_device *dev = info->dev; 771 struct xenbus_transaction xbt; 772 int err; 773 774 pr_debug("%s\n", __func__); 775 776 err = scsifront_alloc_ring(info); 777 if (err) 778 return err; 779 pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn); 780 781 again: 782 err = xenbus_transaction_start(&xbt); 783 if (err) 784 xenbus_dev_fatal(dev, err, "starting transaction"); 785 786 err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u", 787 info->ring_ref); 788 if (err) { 789 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref"); 790 goto fail; 791 } 792 793 err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u", 794 info->evtchn); 795 796 if (err) { 797 xenbus_dev_fatal(dev, err, "%s", "writing event-channel"); 798 goto fail; 799 } 800 801 err = xenbus_transaction_end(xbt, 0); 802 if (err) { 803 if (err == -EAGAIN) 804 goto again; 805 xenbus_dev_fatal(dev, err, "completing transaction"); 806 goto free_sring; 807 } 808 809 return 0; 810 811 fail: 812 xenbus_transaction_end(xbt, 1); 813 free_sring: 814 scsifront_free_ring(info); 815 816 return err; 817 } 818 819 820 static int scsifront_probe(struct xenbus_device *dev, 821 const struct xenbus_device_id *id) 822 { 823 struct vscsifrnt_info *info; 824 struct Scsi_Host *host; 825 int err = -ENOMEM; 826 char name[TASK_COMM_LEN]; 827 828 host = scsi_host_alloc(&scsifront_sht, sizeof(*info)); 829 if (!host) { 830 xenbus_dev_fatal(dev, err, "fail to allocate scsi host"); 831 return err; 832 } 833 info = (struct vscsifrnt_info *)host->hostdata; 834 835 dev_set_drvdata(&dev->dev, info); 836 info->dev = dev; 837 838 bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); 839 840 err = scsifront_init_ring(info); 841 if (err) { 842 scsi_host_put(host); 843 return err; 844 } 845 846 init_waitqueue_head(&info->wq_sync); 847 init_waitqueue_head(&info->wq_pause); 848 spin_lock_init(&info->shadow_lock); 849 850 snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no); 851 852 host->max_id = VSCSIIF_MAX_TARGET; 853 host->max_channel = 0; 854 host->max_lun = VSCSIIF_MAX_LUN; 855 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512; 856 host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE; 857 858 err = scsi_add_host(host, &dev->dev); 859 if (err) { 860 dev_err(&dev->dev, "fail to add scsi host %d\n", err); 861 goto free_sring; 862 } 863 info->host = host; 864 info->host_active = 1; 865 866 xenbus_switch_state(dev, XenbusStateInitialised); 867 868 return 0; 869 870 free_sring: 871 scsifront_free_ring(info); 872 scsi_host_put(host); 873 return err; 874 } 875 876 static int scsifront_resume(struct xenbus_device *dev) 877 { 878 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 879 struct Scsi_Host *host = info->host; 880 int err; 881 882 spin_lock_irq(host->host_lock); 883 884 /* Finish all still pending commands. */ 885 scsifront_finish_all(info); 886 887 spin_unlock_irq(host->host_lock); 888 889 /* Reconnect to dom0. */ 890 scsifront_free_ring(info); 891 err = scsifront_init_ring(info); 892 if (err) { 893 dev_err(&dev->dev, "fail to resume %d\n", err); 894 scsi_host_put(host); 895 return err; 896 } 897 898 xenbus_switch_state(dev, XenbusStateInitialised); 899 900 return 0; 901 } 902 903 static int scsifront_suspend(struct xenbus_device *dev) 904 { 905 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 906 struct Scsi_Host *host = info->host; 907 int err = 0; 908 909 /* No new commands for the backend. */ 910 spin_lock_irq(host->host_lock); 911 info->pause = 1; 912 while (info->callers && !err) { 913 info->waiting_pause = 1; 914 info->wait_ring_available = 0; 915 spin_unlock_irq(host->host_lock); 916 wake_up(&info->wq_sync); 917 err = wait_event_interruptible(info->wq_pause, 918 !info->waiting_pause); 919 spin_lock_irq(host->host_lock); 920 } 921 spin_unlock_irq(host->host_lock); 922 return err; 923 } 924 925 static int scsifront_remove(struct xenbus_device *dev) 926 { 927 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 928 929 pr_debug("%s: %s removed\n", __func__, dev->nodename); 930 931 mutex_lock(&scsifront_mutex); 932 if (info->host_active) { 933 /* Scsi_host not yet removed */ 934 scsi_remove_host(info->host); 935 info->host_active = 0; 936 } 937 mutex_unlock(&scsifront_mutex); 938 939 scsifront_free_ring(info); 940 scsi_host_put(info->host); 941 942 return 0; 943 } 944 945 static void scsifront_disconnect(struct vscsifrnt_info *info) 946 { 947 struct xenbus_device *dev = info->dev; 948 struct Scsi_Host *host = info->host; 949 950 pr_debug("%s: %s disconnect\n", __func__, dev->nodename); 951 952 /* 953 * When this function is executed, all devices of 954 * Frontend have been deleted. 955 * Therefore, it need not block I/O before remove_host. 956 */ 957 958 mutex_lock(&scsifront_mutex); 959 if (info->host_active) { 960 scsi_remove_host(host); 961 info->host_active = 0; 962 } 963 mutex_unlock(&scsifront_mutex); 964 965 xenbus_frontend_closed(dev); 966 } 967 968 static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op) 969 { 970 struct xenbus_device *dev = info->dev; 971 int i, err = 0; 972 char str[64]; 973 char **dir; 974 unsigned int dir_n = 0; 975 unsigned int device_state; 976 unsigned int hst, chn, tgt, lun; 977 struct scsi_device *sdev; 978 979 dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n); 980 if (IS_ERR(dir)) 981 return; 982 983 /* mark current task as the one allowed to modify device states */ 984 BUG_ON(info->curr); 985 info->curr = current; 986 987 for (i = 0; i < dir_n; i++) { 988 /* read status */ 989 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]); 990 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u", 991 &device_state); 992 if (XENBUS_EXIST_ERR(err)) 993 continue; 994 995 /* virtual SCSI device */ 996 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]); 997 err = xenbus_scanf(XBT_NIL, dev->otherend, str, 998 "%u:%u:%u:%u", &hst, &chn, &tgt, &lun); 999 if (XENBUS_EXIST_ERR(err)) 1000 continue; 1001 1002 /* 1003 * Front device state path, used in slave_configure called 1004 * on successfull scsi_add_device, and in slave_destroy called 1005 * on remove of a device. 1006 */ 1007 snprintf(info->dev_state_path, sizeof(info->dev_state_path), 1008 "vscsi-devs/%s/state", dir[i]); 1009 1010 switch (op) { 1011 case VSCSIFRONT_OP_ADD_LUN: 1012 if (device_state != XenbusStateInitialised) 1013 break; 1014 1015 if (scsi_add_device(info->host, chn, tgt, lun)) { 1016 dev_err(&dev->dev, "scsi_add_device\n"); 1017 err = xenbus_printf(XBT_NIL, dev->nodename, 1018 info->dev_state_path, 1019 "%d", XenbusStateClosed); 1020 if (err) 1021 xenbus_dev_error(dev, err, 1022 "%s: writing dev_state_path", __func__); 1023 } 1024 break; 1025 case VSCSIFRONT_OP_DEL_LUN: 1026 if (device_state != XenbusStateClosing) 1027 break; 1028 1029 sdev = scsi_device_lookup(info->host, chn, tgt, lun); 1030 if (sdev) { 1031 scsi_remove_device(sdev); 1032 scsi_device_put(sdev); 1033 } 1034 break; 1035 case VSCSIFRONT_OP_READD_LUN: 1036 if (device_state == XenbusStateConnected) { 1037 err = xenbus_printf(XBT_NIL, dev->nodename, 1038 info->dev_state_path, 1039 "%d", XenbusStateConnected); 1040 if (err) 1041 xenbus_dev_error(dev, err, 1042 "%s: writing dev_state_path", __func__); 1043 } 1044 break; 1045 default: 1046 break; 1047 } 1048 } 1049 1050 info->curr = NULL; 1051 1052 kfree(dir); 1053 } 1054 1055 static void scsifront_read_backend_params(struct xenbus_device *dev, 1056 struct vscsifrnt_info *info) 1057 { 1058 unsigned int sg_grant, nr_segs; 1059 struct Scsi_Host *host = info->host; 1060 1061 sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0); 1062 nr_segs = min_t(unsigned int, sg_grant, SG_ALL); 1063 nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE); 1064 nr_segs = min_t(unsigned int, nr_segs, 1065 VSCSIIF_SG_TABLESIZE * PAGE_SIZE / 1066 sizeof(struct scsiif_request_segment)); 1067 1068 if (!info->pause && sg_grant) 1069 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs); 1070 else if (info->pause && nr_segs < host->sg_tablesize) 1071 dev_warn(&dev->dev, 1072 "SG entries decreased from %d to %u - device may not work properly anymore\n", 1073 host->sg_tablesize, nr_segs); 1074 1075 host->sg_tablesize = nr_segs; 1076 host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512; 1077 } 1078 1079 static void scsifront_backend_changed(struct xenbus_device *dev, 1080 enum xenbus_state backend_state) 1081 { 1082 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 1083 1084 pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state); 1085 1086 switch (backend_state) { 1087 case XenbusStateUnknown: 1088 case XenbusStateInitialising: 1089 case XenbusStateInitWait: 1090 case XenbusStateInitialised: 1091 break; 1092 1093 case XenbusStateConnected: 1094 scsifront_read_backend_params(dev, info); 1095 1096 if (info->pause) { 1097 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN); 1098 xenbus_switch_state(dev, XenbusStateConnected); 1099 info->pause = 0; 1100 return; 1101 } 1102 1103 if (xenbus_read_driver_state(dev->nodename) == 1104 XenbusStateInitialised) 1105 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN); 1106 1107 if (dev->state != XenbusStateConnected) 1108 xenbus_switch_state(dev, XenbusStateConnected); 1109 break; 1110 1111 case XenbusStateClosed: 1112 if (dev->state == XenbusStateClosed) 1113 break; 1114 fallthrough; /* Missed the backend's Closing state */ 1115 case XenbusStateClosing: 1116 scsifront_disconnect(info); 1117 break; 1118 1119 case XenbusStateReconfiguring: 1120 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN); 1121 xenbus_switch_state(dev, XenbusStateReconfiguring); 1122 break; 1123 1124 case XenbusStateReconfigured: 1125 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN); 1126 xenbus_switch_state(dev, XenbusStateConnected); 1127 break; 1128 } 1129 } 1130 1131 static const struct xenbus_device_id scsifront_ids[] = { 1132 { "vscsi" }, 1133 { "" } 1134 }; 1135 1136 static struct xenbus_driver scsifront_driver = { 1137 .ids = scsifront_ids, 1138 .probe = scsifront_probe, 1139 .remove = scsifront_remove, 1140 .resume = scsifront_resume, 1141 .suspend = scsifront_suspend, 1142 .otherend_changed = scsifront_backend_changed, 1143 }; 1144 1145 static int __init scsifront_init(void) 1146 { 1147 if (!xen_domain()) 1148 return -ENODEV; 1149 1150 return xenbus_register_frontend(&scsifront_driver); 1151 } 1152 module_init(scsifront_init); 1153 1154 static void __exit scsifront_exit(void) 1155 { 1156 xenbus_unregister_driver(&scsifront_driver); 1157 } 1158 module_exit(scsifront_exit); 1159 1160 MODULE_DESCRIPTION("Xen SCSI frontend driver"); 1161 MODULE_LICENSE("GPL"); 1162 MODULE_ALIAS("xen:vscsi"); 1163 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>"); 1164