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 79struct vscsifrnt_shadow { 80 /* command between backend and frontend */ 81 unsigned char act; 82 uint16_t rqid; 83 84 unsigned int nr_grants; /* number of grants in gref[] */ 85 struct scsiif_request_segment *sg; /* scatter/gather elements */ 86 87 /* Do reset or abort function. */ 88 wait_queue_head_t wq_reset; /* reset work queue */ 89 int wait_reset; /* reset work queue condition */ 90 int32_t rslt_reset; /* reset response status: */ 91 /* SUCCESS or FAILED or: */ 92#define RSLT_RESET_WAITING 0 93#define RSLT_RESET_ERR -1 94 95 /* Requested struct scsi_cmnd is stored from kernel. */ 96 struct scsi_cmnd *sc; 97 int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL]; 98}; 99 100struct vscsifrnt_info { 101 struct xenbus_device *dev; 102 103 struct Scsi_Host *host; 104 int host_active; 105 106 unsigned int evtchn; 107 unsigned int irq; 108 109 grant_ref_t ring_ref; 110 struct vscsiif_front_ring ring; 111 struct vscsiif_response ring_rsp; 112 113 spinlock_t shadow_lock; 114 DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS); 115 struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS]; 116 117 /* Following items are protected by the host lock. */ 118 wait_queue_head_t wq_sync; 119 wait_queue_head_t wq_pause; 120 unsigned int wait_ring_available:1; 121 unsigned int waiting_pause:1; 122 unsigned int pause:1; 123 unsigned callers; 124 125 char dev_state_path[64]; 126 struct task_struct *curr; 127}; 128 129static DEFINE_MUTEX(scsifront_mutex); 130 131static void scsifront_wake_up(struct vscsifrnt_info *info) 132{ 133 info->wait_ring_available = 0; 134 wake_up(&info->wq_sync); 135} 136 137static int scsifront_get_rqid(struct vscsifrnt_info *info) 138{ 139 unsigned long flags; 140 int free; 141 142 spin_lock_irqsave(&info->shadow_lock, flags); 143 144 free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); 145 __clear_bit(free, info->shadow_free_bitmap); 146 147 spin_unlock_irqrestore(&info->shadow_lock, flags); 148 149 return free; 150} 151 152static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id) 153{ 154 int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); 155 156 __set_bit(id, info->shadow_free_bitmap); 157 info->shadow[id] = NULL; 158 159 return empty || info->wait_ring_available; 160} 161 162static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id) 163{ 164 unsigned long flags; 165 int kick; 166 167 spin_lock_irqsave(&info->shadow_lock, flags); 168 kick = _scsifront_put_rqid(info, id); 169 spin_unlock_irqrestore(&info->shadow_lock, flags); 170 171 if (kick) 172 scsifront_wake_up(info); 173} 174 175static struct vscsiif_request *scsifront_pre_req(struct vscsifrnt_info *info) 176{ 177 struct vscsiif_front_ring *ring = &(info->ring); 178 struct vscsiif_request *ring_req; 179 uint32_t id; 180 181 id = scsifront_get_rqid(info); /* use id in response */ 182 if (id >= VSCSIIF_MAX_REQS) 183 return NULL; 184 185 ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt); 186 187 ring->req_prod_pvt++; 188 189 ring_req->rqid = (uint16_t)id; 190 191 return ring_req; 192} 193 194static void scsifront_do_request(struct vscsifrnt_info *info) 195{ 196 struct vscsiif_front_ring *ring = &(info->ring); 197 int notify; 198 199 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify); 200 if (notify) 201 notify_remote_via_irq(info->irq); 202} 203 204static void scsifront_gnttab_done(struct vscsifrnt_info *info, uint32_t id) 205{ 206 struct vscsifrnt_shadow *s = info->shadow[id]; 207 int i; 208 209 if (s->sc->sc_data_direction == DMA_NONE) 210 return; 211 212 for (i = 0; i < s->nr_grants; i++) { 213 if (unlikely(gnttab_query_foreign_access(s->gref[i]) != 0)) { 214 shost_printk(KERN_ALERT, info->host, KBUILD_MODNAME 215 "grant still in use by backend\n"); 216 BUG(); 217 } 218 gnttab_end_foreign_access(s->gref[i], 0, 0UL); 219 } 220 221 kfree(s->sg); 222} 223 224static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info, 225 struct vscsiif_response *ring_rsp) 226{ 227 struct scsi_cmnd *sc; 228 uint32_t id; 229 uint8_t sense_len; 230 231 id = ring_rsp->rqid; 232 sc = info->shadow[id]->sc; 233 234 BUG_ON(sc == NULL); 235 236 scsifront_gnttab_done(info, id); 237 scsifront_put_rqid(info, id); 238 239 sc->result = ring_rsp->rslt; 240 scsi_set_resid(sc, ring_rsp->residual_len); 241 242 sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE, 243 ring_rsp->sense_len); 244 245 if (sense_len) 246 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len); 247 248 sc->scsi_done(sc); 249} 250 251static void scsifront_sync_cmd_done(struct vscsifrnt_info *info, 252 struct vscsiif_response *ring_rsp) 253{ 254 uint16_t id = ring_rsp->rqid; 255 unsigned long flags; 256 struct vscsifrnt_shadow *shadow = info->shadow[id]; 257 int kick; 258 259 spin_lock_irqsave(&info->shadow_lock, flags); 260 shadow->wait_reset = 1; 261 switch (shadow->rslt_reset) { 262 case RSLT_RESET_WAITING: 263 shadow->rslt_reset = ring_rsp->rslt; 264 break; 265 case RSLT_RESET_ERR: 266 kick = _scsifront_put_rqid(info, id); 267 spin_unlock_irqrestore(&info->shadow_lock, flags); 268 kfree(shadow); 269 if (kick) 270 scsifront_wake_up(info); 271 return; 272 default: 273 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME 274 "bad reset state %d, possibly leaking %u\n", 275 shadow->rslt_reset, id); 276 break; 277 } 278 spin_unlock_irqrestore(&info->shadow_lock, flags); 279 280 wake_up(&shadow->wq_reset); 281} 282 283static void scsifront_do_response(struct vscsifrnt_info *info, 284 struct vscsiif_response *ring_rsp) 285{ 286 if (WARN(ring_rsp->rqid >= VSCSIIF_MAX_REQS || 287 test_bit(ring_rsp->rqid, info->shadow_free_bitmap), 288 "illegal rqid %u returned by backend!\n", ring_rsp->rqid)) 289 return; 290 291 if (info->shadow[ring_rsp->rqid]->act == VSCSIIF_ACT_SCSI_CDB) 292 scsifront_cdb_cmd_done(info, ring_rsp); 293 else 294 scsifront_sync_cmd_done(info, ring_rsp); 295} 296 297static int scsifront_ring_drain(struct vscsifrnt_info *info) 298{ 299 struct vscsiif_response *ring_rsp; 300 RING_IDX i, rp; 301 int more_to_do = 0; 302 303 rp = info->ring.sring->rsp_prod; 304 rmb(); /* ordering required respective to dom0 */ 305 for (i = info->ring.rsp_cons; i != rp; i++) { 306 ring_rsp = RING_GET_RESPONSE(&info->ring, i); 307 scsifront_do_response(info, ring_rsp); 308 } 309 310 info->ring.rsp_cons = i; 311 312 if (i != info->ring.req_prod_pvt) 313 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); 314 else 315 info->ring.sring->rsp_event = i + 1; 316 317 return more_to_do; 318} 319 320static int scsifront_cmd_done(struct vscsifrnt_info *info) 321{ 322 int more_to_do; 323 unsigned long flags; 324 325 spin_lock_irqsave(info->host->host_lock, flags); 326 327 more_to_do = scsifront_ring_drain(info); 328 329 info->wait_ring_available = 0; 330 331 spin_unlock_irqrestore(info->host->host_lock, flags); 332 333 wake_up(&info->wq_sync); 334 335 return more_to_do; 336} 337 338static irqreturn_t scsifront_irq_fn(int irq, void *dev_id) 339{ 340 struct vscsifrnt_info *info = dev_id; 341 342 while (scsifront_cmd_done(info)) 343 /* Yield point for this unbounded loop. */ 344 cond_resched(); 345 346 return IRQ_HANDLED; 347} 348 349static void scsifront_finish_all(struct vscsifrnt_info *info) 350{ 351 unsigned i; 352 struct vscsiif_response resp; 353 354 scsifront_ring_drain(info); 355 356 for (i = 0; i < VSCSIIF_MAX_REQS; i++) { 357 if (test_bit(i, info->shadow_free_bitmap)) 358 continue; 359 resp.rqid = i; 360 resp.sense_len = 0; 361 resp.rslt = DID_RESET << 16; 362 resp.residual_len = 0; 363 scsifront_do_response(info, &resp); 364 } 365} 366 367static int map_data_for_request(struct vscsifrnt_info *info, 368 struct scsi_cmnd *sc, 369 struct vscsiif_request *ring_req, 370 struct vscsifrnt_shadow *shadow) 371{ 372 grant_ref_t gref_head; 373 struct page *page; 374 int err, ref, ref_cnt = 0; 375 int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE); 376 unsigned int i, off, len, bytes; 377 unsigned int data_len = scsi_bufflen(sc); 378 unsigned int data_grants = 0, seg_grants = 0; 379 struct scatterlist *sg; 380 struct scsiif_request_segment *seg; 381 382 ring_req->nr_segments = 0; 383 if (sc->sc_data_direction == DMA_NONE || !data_len) 384 return 0; 385 386 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) 387 data_grants += PFN_UP(sg->offset + sg->length); 388 389 if (data_grants > VSCSIIF_SG_TABLESIZE) { 390 if (data_grants > info->host->sg_tablesize) { 391 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME 392 "Unable to map request_buffer for command!\n"); 393 return -E2BIG; 394 } 395 seg_grants = vscsiif_grants_sg(data_grants); 396 shadow->sg = kcalloc(data_grants, 397 sizeof(struct scsiif_request_segment), GFP_ATOMIC); 398 if (!shadow->sg) 399 return -ENOMEM; 400 } 401 seg = shadow->sg ? : ring_req->seg; 402 403 err = gnttab_alloc_grant_references(seg_grants + data_grants, 404 &gref_head); 405 if (err) { 406 kfree(shadow->sg); 407 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME 408 "gnttab_alloc_grant_references() error\n"); 409 return -ENOMEM; 410 } 411 412 if (seg_grants) { 413 page = virt_to_page(seg); 414 off = (unsigned long)seg & ~PAGE_MASK; 415 len = sizeof(struct scsiif_request_segment) * data_grants; 416 while (len > 0) { 417 bytes = min_t(unsigned int, len, PAGE_SIZE - off); 418 419 ref = gnttab_claim_grant_reference(&gref_head); 420 BUG_ON(ref == -ENOSPC); 421 422 gnttab_grant_foreign_access_ref(ref, 423 info->dev->otherend_id, 424 xen_page_to_gfn(page), 1); 425 shadow->gref[ref_cnt] = ref; 426 ring_req->seg[ref_cnt].gref = ref; 427 ring_req->seg[ref_cnt].offset = (uint16_t)off; 428 ring_req->seg[ref_cnt].length = (uint16_t)bytes; 429 430 page++; 431 len -= bytes; 432 off = 0; 433 ref_cnt++; 434 } 435 BUG_ON(seg_grants < ref_cnt); 436 seg_grants = ref_cnt; 437 } 438 439 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) { 440 page = sg_page(sg); 441 off = sg->offset; 442 len = sg->length; 443 444 while (len > 0 && data_len > 0) { 445 /* 446 * sg sends a scatterlist that is larger than 447 * the data_len it wants transferred for certain 448 * IO sizes. 449 */ 450 bytes = min_t(unsigned int, len, PAGE_SIZE - off); 451 bytes = min(bytes, data_len); 452 453 ref = gnttab_claim_grant_reference(&gref_head); 454 BUG_ON(ref == -ENOSPC); 455 456 gnttab_grant_foreign_access_ref(ref, 457 info->dev->otherend_id, 458 xen_page_to_gfn(page), 459 grant_ro); 460 461 shadow->gref[ref_cnt] = ref; 462 seg->gref = ref; 463 seg->offset = (uint16_t)off; 464 seg->length = (uint16_t)bytes; 465 466 page++; 467 seg++; 468 len -= bytes; 469 data_len -= bytes; 470 off = 0; 471 ref_cnt++; 472 } 473 } 474 475 if (seg_grants) 476 ring_req->nr_segments = VSCSIIF_SG_GRANT | seg_grants; 477 else 478 ring_req->nr_segments = (uint8_t)ref_cnt; 479 shadow->nr_grants = ref_cnt; 480 481 return 0; 482} 483 484static struct vscsiif_request *scsifront_command2ring( 485 struct vscsifrnt_info *info, struct scsi_cmnd *sc, 486 struct vscsifrnt_shadow *shadow) 487{ 488 struct vscsiif_request *ring_req; 489 490 memset(shadow, 0, sizeof(*shadow)); 491 492 ring_req = scsifront_pre_req(info); 493 if (!ring_req) 494 return NULL; 495 496 info->shadow[ring_req->rqid] = shadow; 497 shadow->rqid = ring_req->rqid; 498 499 ring_req->id = sc->device->id; 500 ring_req->lun = sc->device->lun; 501 ring_req->channel = sc->device->channel; 502 ring_req->cmd_len = sc->cmd_len; 503 504 BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE); 505 506 memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len); 507 508 ring_req->sc_data_direction = (uint8_t)sc->sc_data_direction; 509 ring_req->timeout_per_command = sc->request->timeout / HZ; 510 511 return ring_req; 512} 513 514static int scsifront_enter(struct vscsifrnt_info *info) 515{ 516 if (info->pause) 517 return 1; 518 info->callers++; 519 return 0; 520} 521 522static void scsifront_return(struct vscsifrnt_info *info) 523{ 524 info->callers--; 525 if (info->callers) 526 return; 527 528 if (!info->waiting_pause) 529 return; 530 531 info->waiting_pause = 0; 532 wake_up(&info->wq_pause); 533} 534 535static int scsifront_queuecommand(struct Scsi_Host *shost, 536 struct scsi_cmnd *sc) 537{ 538 struct vscsifrnt_info *info = shost_priv(shost); 539 struct vscsiif_request *ring_req; 540 struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc); 541 unsigned long flags; 542 int err; 543 uint16_t rqid; 544 545 spin_lock_irqsave(shost->host_lock, flags); 546 if (scsifront_enter(info)) { 547 spin_unlock_irqrestore(shost->host_lock, flags); 548 return SCSI_MLQUEUE_HOST_BUSY; 549 } 550 if (RING_FULL(&info->ring)) 551 goto busy; 552 553 ring_req = scsifront_command2ring(info, sc, shadow); 554 if (!ring_req) 555 goto busy; 556 557 sc->result = 0; 558 559 rqid = ring_req->rqid; 560 ring_req->act = VSCSIIF_ACT_SCSI_CDB; 561 562 shadow->sc = sc; 563 shadow->act = VSCSIIF_ACT_SCSI_CDB; 564 565 err = map_data_for_request(info, sc, ring_req, shadow); 566 if (err < 0) { 567 pr_debug("%s: err %d\n", __func__, err); 568 scsifront_put_rqid(info, rqid); 569 scsifront_return(info); 570 spin_unlock_irqrestore(shost->host_lock, flags); 571 if (err == -ENOMEM) 572 return SCSI_MLQUEUE_HOST_BUSY; 573 sc->result = DID_ERROR << 16; 574 sc->scsi_done(sc); 575 return 0; 576 } 577 578 scsifront_do_request(info); 579 scsifront_return(info); 580 spin_unlock_irqrestore(shost->host_lock, flags); 581 582 return 0; 583 584busy: 585 scsifront_return(info); 586 spin_unlock_irqrestore(shost->host_lock, flags); 587 pr_debug("%s: busy\n", __func__); 588 return SCSI_MLQUEUE_HOST_BUSY; 589} 590 591/* 592 * Any exception handling (reset or abort) must be forwarded to the backend. 593 * We have to wait until an answer is returned. This answer contains the 594 * result to be returned to the requestor. 595 */ 596static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act) 597{ 598 struct Scsi_Host *host = sc->device->host; 599 struct vscsifrnt_info *info = shost_priv(host); 600 struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc); 601 struct vscsiif_request *ring_req; 602 int err = 0; 603 604 shadow = kmalloc(sizeof(*shadow), GFP_NOIO); 605 if (!shadow) 606 return FAILED; 607 608 spin_lock_irq(host->host_lock); 609 610 for (;;) { 611 if (!RING_FULL(&info->ring)) { 612 ring_req = scsifront_command2ring(info, sc, shadow); 613 if (ring_req) 614 break; 615 } 616 if (err || info->pause) { 617 spin_unlock_irq(host->host_lock); 618 kfree(shadow); 619 return FAILED; 620 } 621 info->wait_ring_available = 1; 622 spin_unlock_irq(host->host_lock); 623 err = wait_event_interruptible(info->wq_sync, 624 !info->wait_ring_available); 625 spin_lock_irq(host->host_lock); 626 } 627 628 if (scsifront_enter(info)) { 629 spin_unlock_irq(host->host_lock); 630 return FAILED; 631 } 632 633 ring_req->act = act; 634 ring_req->ref_rqid = s->rqid; 635 636 shadow->act = act; 637 shadow->rslt_reset = RSLT_RESET_WAITING; 638 init_waitqueue_head(&shadow->wq_reset); 639 640 ring_req->nr_segments = 0; 641 642 scsifront_do_request(info); 643 644 spin_unlock_irq(host->host_lock); 645 err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset); 646 spin_lock_irq(host->host_lock); 647 648 if (!err) { 649 err = shadow->rslt_reset; 650 scsifront_put_rqid(info, shadow->rqid); 651 kfree(shadow); 652 } else { 653 spin_lock(&info->shadow_lock); 654 shadow->rslt_reset = RSLT_RESET_ERR; 655 spin_unlock(&info->shadow_lock); 656 err = FAILED; 657 } 658 659 scsifront_return(info); 660 spin_unlock_irq(host->host_lock); 661 return err; 662} 663 664static int scsifront_eh_abort_handler(struct scsi_cmnd *sc) 665{ 666 pr_debug("%s\n", __func__); 667 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT); 668} 669 670static int scsifront_dev_reset_handler(struct scsi_cmnd *sc) 671{ 672 pr_debug("%s\n", __func__); 673 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET); 674} 675 676static int scsifront_sdev_configure(struct scsi_device *sdev) 677{ 678 struct vscsifrnt_info *info = shost_priv(sdev->host); 679 680 if (info && current == info->curr) 681 xenbus_printf(XBT_NIL, info->dev->nodename, 682 info->dev_state_path, "%d", XenbusStateConnected); 683 684 return 0; 685} 686 687static void scsifront_sdev_destroy(struct scsi_device *sdev) 688{ 689 struct vscsifrnt_info *info = shost_priv(sdev->host); 690 691 if (info && current == info->curr) 692 xenbus_printf(XBT_NIL, info->dev->nodename, 693 info->dev_state_path, "%d", XenbusStateClosed); 694} 695 696static struct scsi_host_template scsifront_sht = { 697 .module = THIS_MODULE, 698 .name = "Xen SCSI frontend driver", 699 .queuecommand = scsifront_queuecommand, 700 .eh_abort_handler = scsifront_eh_abort_handler, 701 .eh_device_reset_handler = scsifront_dev_reset_handler, 702 .slave_configure = scsifront_sdev_configure, 703 .slave_destroy = scsifront_sdev_destroy, 704 .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN, 705 .can_queue = VSCSIIF_MAX_REQS, 706 .this_id = -1, 707 .cmd_size = sizeof(struct vscsifrnt_shadow), 708 .sg_tablesize = VSCSIIF_SG_TABLESIZE, 709 .use_clustering = DISABLE_CLUSTERING, 710 .proc_name = "scsifront", 711}; 712 713static int scsifront_alloc_ring(struct vscsifrnt_info *info) 714{ 715 struct xenbus_device *dev = info->dev; 716 struct vscsiif_sring *sring; 717 grant_ref_t gref; 718 int err = -ENOMEM; 719 720 /***** Frontend to Backend ring start *****/ 721 sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL); 722 if (!sring) { 723 xenbus_dev_fatal(dev, err, 724 "fail to allocate shared ring (Front to Back)"); 725 return err; 726 } 727 SHARED_RING_INIT(sring); 728 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); 729 730 err = xenbus_grant_ring(dev, sring, 1, &gref); 731 if (err < 0) { 732 free_page((unsigned long)sring); 733 xenbus_dev_fatal(dev, err, 734 "fail to grant shared ring (Front to Back)"); 735 return err; 736 } 737 info->ring_ref = gref; 738 739 err = xenbus_alloc_evtchn(dev, &info->evtchn); 740 if (err) { 741 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn"); 742 goto free_gnttab; 743 } 744 745 err = bind_evtchn_to_irq(info->evtchn); 746 if (err <= 0) { 747 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq"); 748 goto free_gnttab; 749 } 750 751 info->irq = err; 752 753 err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn, 754 IRQF_ONESHOT, "scsifront", info); 755 if (err) { 756 xenbus_dev_fatal(dev, err, "request_threaded_irq"); 757 goto free_irq; 758 } 759 760 return 0; 761 762/* free resource */ 763free_irq: 764 unbind_from_irqhandler(info->irq, info); 765free_gnttab: 766 gnttab_end_foreign_access(info->ring_ref, 0, 767 (unsigned long)info->ring.sring); 768 769 return err; 770} 771 772static void scsifront_free_ring(struct vscsifrnt_info *info) 773{ 774 unbind_from_irqhandler(info->irq, info); 775 gnttab_end_foreign_access(info->ring_ref, 0, 776 (unsigned long)info->ring.sring); 777} 778 779static int scsifront_init_ring(struct vscsifrnt_info *info) 780{ 781 struct xenbus_device *dev = info->dev; 782 struct xenbus_transaction xbt; 783 int err; 784 785 pr_debug("%s\n", __func__); 786 787 err = scsifront_alloc_ring(info); 788 if (err) 789 return err; 790 pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn); 791 792again: 793 err = xenbus_transaction_start(&xbt); 794 if (err) 795 xenbus_dev_fatal(dev, err, "starting transaction"); 796 797 err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u", 798 info->ring_ref); 799 if (err) { 800 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref"); 801 goto fail; 802 } 803 804 err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u", 805 info->evtchn); 806 807 if (err) { 808 xenbus_dev_fatal(dev, err, "%s", "writing event-channel"); 809 goto fail; 810 } 811 812 err = xenbus_transaction_end(xbt, 0); 813 if (err) { 814 if (err == -EAGAIN) 815 goto again; 816 xenbus_dev_fatal(dev, err, "completing transaction"); 817 goto free_sring; 818 } 819 820 return 0; 821 822fail: 823 xenbus_transaction_end(xbt, 1); 824free_sring: 825 scsifront_free_ring(info); 826 827 return err; 828} 829 830 831static int scsifront_probe(struct xenbus_device *dev, 832 const struct xenbus_device_id *id) 833{ 834 struct vscsifrnt_info *info; 835 struct Scsi_Host *host; 836 int err = -ENOMEM; 837 char name[TASK_COMM_LEN]; 838 839 host = scsi_host_alloc(&scsifront_sht, sizeof(*info)); 840 if (!host) { 841 xenbus_dev_fatal(dev, err, "fail to allocate scsi host"); 842 return err; 843 } 844 info = (struct vscsifrnt_info *)host->hostdata; 845 846 dev_set_drvdata(&dev->dev, info); 847 info->dev = dev; 848 849 bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); 850 851 err = scsifront_init_ring(info); 852 if (err) { 853 scsi_host_put(host); 854 return err; 855 } 856 857 init_waitqueue_head(&info->wq_sync); 858 init_waitqueue_head(&info->wq_pause); 859 spin_lock_init(&info->shadow_lock); 860 861 snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no); 862 863 host->max_id = VSCSIIF_MAX_TARGET; 864 host->max_channel = 0; 865 host->max_lun = VSCSIIF_MAX_LUN; 866 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512; 867 host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE; 868 869 err = scsi_add_host(host, &dev->dev); 870 if (err) { 871 dev_err(&dev->dev, "fail to add scsi host %d\n", err); 872 goto free_sring; 873 } 874 info->host = host; 875 info->host_active = 1; 876 877 xenbus_switch_state(dev, XenbusStateInitialised); 878 879 return 0; 880 881free_sring: 882 scsifront_free_ring(info); 883 scsi_host_put(host); 884 return err; 885} 886 887static int scsifront_resume(struct xenbus_device *dev) 888{ 889 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 890 struct Scsi_Host *host = info->host; 891 int err; 892 893 spin_lock_irq(host->host_lock); 894 895 /* Finish all still pending commands. */ 896 scsifront_finish_all(info); 897 898 spin_unlock_irq(host->host_lock); 899 900 /* Reconnect to dom0. */ 901 scsifront_free_ring(info); 902 err = scsifront_init_ring(info); 903 if (err) { 904 dev_err(&dev->dev, "fail to resume %d\n", err); 905 scsi_host_put(host); 906 return err; 907 } 908 909 xenbus_switch_state(dev, XenbusStateInitialised); 910 911 return 0; 912} 913 914static int scsifront_suspend(struct xenbus_device *dev) 915{ 916 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 917 struct Scsi_Host *host = info->host; 918 int err = 0; 919 920 /* No new commands for the backend. */ 921 spin_lock_irq(host->host_lock); 922 info->pause = 1; 923 while (info->callers && !err) { 924 info->waiting_pause = 1; 925 info->wait_ring_available = 0; 926 spin_unlock_irq(host->host_lock); 927 wake_up(&info->wq_sync); 928 err = wait_event_interruptible(info->wq_pause, 929 !info->waiting_pause); 930 spin_lock_irq(host->host_lock); 931 } 932 spin_unlock_irq(host->host_lock); 933 return err; 934} 935 936static int scsifront_remove(struct xenbus_device *dev) 937{ 938 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 939 940 pr_debug("%s: %s removed\n", __func__, dev->nodename); 941 942 mutex_lock(&scsifront_mutex); 943 if (info->host_active) { 944 /* Scsi_host not yet removed */ 945 scsi_remove_host(info->host); 946 info->host_active = 0; 947 } 948 mutex_unlock(&scsifront_mutex); 949 950 scsifront_free_ring(info); 951 scsi_host_put(info->host); 952 953 return 0; 954} 955 956static void scsifront_disconnect(struct vscsifrnt_info *info) 957{ 958 struct xenbus_device *dev = info->dev; 959 struct Scsi_Host *host = info->host; 960 961 pr_debug("%s: %s disconnect\n", __func__, dev->nodename); 962 963 /* 964 * When this function is executed, all devices of 965 * Frontend have been deleted. 966 * Therefore, it need not block I/O before remove_host. 967 */ 968 969 mutex_lock(&scsifront_mutex); 970 if (info->host_active) { 971 scsi_remove_host(host); 972 info->host_active = 0; 973 } 974 mutex_unlock(&scsifront_mutex); 975 976 xenbus_frontend_closed(dev); 977} 978 979static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op) 980{ 981 struct xenbus_device *dev = info->dev; 982 int i, err = 0; 983 char str[64]; 984 char **dir; 985 unsigned int dir_n = 0; 986 unsigned int device_state; 987 unsigned int hst, chn, tgt, lun; 988 struct scsi_device *sdev; 989 990 dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n); 991 if (IS_ERR(dir)) 992 return; 993 994 /* mark current task as the one allowed to modify device states */ 995 BUG_ON(info->curr); 996 info->curr = current; 997 998 for (i = 0; i < dir_n; i++) { 999 /* read status */ 1000 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]); 1001 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u", 1002 &device_state); 1003 if (XENBUS_EXIST_ERR(err)) 1004 continue; 1005 1006 /* virtual SCSI device */ 1007 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]); 1008 err = xenbus_scanf(XBT_NIL, dev->otherend, str, 1009 "%u:%u:%u:%u", &hst, &chn, &tgt, &lun); 1010 if (XENBUS_EXIST_ERR(err)) 1011 continue; 1012 1013 /* 1014 * Front device state path, used in slave_configure called 1015 * on successfull scsi_add_device, and in slave_destroy called 1016 * on remove of a device. 1017 */ 1018 snprintf(info->dev_state_path, sizeof(info->dev_state_path), 1019 "vscsi-devs/%s/state", dir[i]); 1020 1021 switch (op) { 1022 case VSCSIFRONT_OP_ADD_LUN: 1023 if (device_state != XenbusStateInitialised) 1024 break; 1025 1026 if (scsi_add_device(info->host, chn, tgt, lun)) { 1027 dev_err(&dev->dev, "scsi_add_device\n"); 1028 xenbus_printf(XBT_NIL, dev->nodename, 1029 info->dev_state_path, 1030 "%d", XenbusStateClosed); 1031 } 1032 break; 1033 case VSCSIFRONT_OP_DEL_LUN: 1034 if (device_state != XenbusStateClosing) 1035 break; 1036 1037 sdev = scsi_device_lookup(info->host, chn, tgt, lun); 1038 if (sdev) { 1039 scsi_remove_device(sdev); 1040 scsi_device_put(sdev); 1041 } 1042 break; 1043 case VSCSIFRONT_OP_READD_LUN: 1044 if (device_state == XenbusStateConnected) 1045 xenbus_printf(XBT_NIL, dev->nodename, 1046 info->dev_state_path, 1047 "%d", XenbusStateConnected); 1048 break; 1049 default: 1050 break; 1051 } 1052 } 1053 1054 info->curr = NULL; 1055 1056 kfree(dir); 1057} 1058 1059static void scsifront_read_backend_params(struct xenbus_device *dev, 1060 struct vscsifrnt_info *info) 1061{ 1062 unsigned int sg_grant, nr_segs; 1063 int ret; 1064 struct Scsi_Host *host = info->host; 1065 1066 ret = xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg-grant", "%u", 1067 &sg_grant); 1068 if (ret != 1) 1069 sg_grant = 0; 1070 nr_segs = min_t(unsigned int, sg_grant, SG_ALL); 1071 nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE); 1072 nr_segs = min_t(unsigned int, nr_segs, 1073 VSCSIIF_SG_TABLESIZE * PAGE_SIZE / 1074 sizeof(struct scsiif_request_segment)); 1075 1076 if (!info->pause && sg_grant) 1077 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs); 1078 else if (info->pause && nr_segs < host->sg_tablesize) 1079 dev_warn(&dev->dev, 1080 "SG entries decreased from %d to %u - device may not work properly anymore\n", 1081 host->sg_tablesize, nr_segs); 1082 1083 host->sg_tablesize = nr_segs; 1084 host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512; 1085} 1086 1087static void scsifront_backend_changed(struct xenbus_device *dev, 1088 enum xenbus_state backend_state) 1089{ 1090 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 1091 1092 pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state); 1093 1094 switch (backend_state) { 1095 case XenbusStateUnknown: 1096 case XenbusStateInitialising: 1097 case XenbusStateInitWait: 1098 case XenbusStateInitialised: 1099 break; 1100 1101 case XenbusStateConnected: 1102 scsifront_read_backend_params(dev, info); 1103 1104 if (info->pause) { 1105 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN); 1106 xenbus_switch_state(dev, XenbusStateConnected); 1107 info->pause = 0; 1108 return; 1109 } 1110 1111 if (xenbus_read_driver_state(dev->nodename) == 1112 XenbusStateInitialised) 1113 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN); 1114 1115 if (dev->state != XenbusStateConnected) 1116 xenbus_switch_state(dev, XenbusStateConnected); 1117 break; 1118 1119 case XenbusStateClosed: 1120 if (dev->state == XenbusStateClosed) 1121 break; 1122 /* Missed the backend's Closing state -- fallthrough */ 1123 case XenbusStateClosing: 1124 scsifront_disconnect(info); 1125 break; 1126 1127 case XenbusStateReconfiguring: 1128 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN); 1129 xenbus_switch_state(dev, XenbusStateReconfiguring); 1130 break; 1131 1132 case XenbusStateReconfigured: 1133 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN); 1134 xenbus_switch_state(dev, XenbusStateConnected); 1135 break; 1136 } 1137} 1138 1139static const struct xenbus_device_id scsifront_ids[] = { 1140 { "vscsi" }, 1141 { "" } 1142}; 1143 1144static struct xenbus_driver scsifront_driver = { 1145 .ids = scsifront_ids, 1146 .probe = scsifront_probe, 1147 .remove = scsifront_remove, 1148 .resume = scsifront_resume, 1149 .suspend = scsifront_suspend, 1150 .otherend_changed = scsifront_backend_changed, 1151}; 1152 1153static int __init scsifront_init(void) 1154{ 1155 if (!xen_domain()) 1156 return -ENODEV; 1157 1158 return xenbus_register_frontend(&scsifront_driver); 1159} 1160module_init(scsifront_init); 1161 1162static void __exit scsifront_exit(void) 1163{ 1164 xenbus_unregister_driver(&scsifront_driver); 1165} 1166module_exit(scsifront_exit); 1167 1168MODULE_DESCRIPTION("Xen SCSI frontend driver"); 1169MODULE_LICENSE("GPL"); 1170MODULE_ALIAS("xen:vscsi"); 1171MODULE_AUTHOR("Juergen Gross <jgross@suse.com>"); 1172