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1/*2 * Xen SCSI frontend driver3 *4 * Copyright (c) 2008, FUJITSU Limited5 *6 * This program is free software; you can redistribute it and/or7 * modify it under the terms of the GNU General Public License version 28 * as published by the Free Software Foundation; or, when distributed9 * separately from the Linux kernel or incorporated into other10 * software packages, subject to the following license:11 *12 * Permission is hereby granted, free of charge, to any person obtaining a copy13 * of this source file (the "Software"), to deal in the Software without14 * 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 to17 * the following conditions:18 *19 * The above copyright notice and this permission notice shall be included in20 * all copies or substantial portions of the Software.21 *22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING27 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS28 * 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#define VSCSIFRONT_OP_ADD_LUN 162#define VSCSIFRONT_OP_DEL_LUN 263#define VSCSIFRONT_OP_READD_LUN 364 65/* Tuning point. */66#define VSCSIIF_DEFAULT_CMD_PER_LUN 1067#define VSCSIIF_MAX_TARGET 6468#define VSCSIIF_MAX_LUN 25569 70#define VSCSIIF_RING_SIZE __CONST_RING_SIZE(vscsiif, PAGE_SIZE)71#define VSCSIIF_MAX_REQS VSCSIIF_RING_SIZE72 73#define vscsiif_grants_sg(_sg) (PFN_UP((_sg) * \74 sizeof(struct scsiif_request_segment)))75 76struct vscsifrnt_shadow {77 /* command between backend and frontend */78 unsigned char act;79 uint8_t nr_segments;80 uint16_t rqid;81 uint16_t ref_rqid;82 83 bool inflight;84 85 unsigned int nr_grants; /* number of grants in gref[] */86 struct scsiif_request_segment *sg; /* scatter/gather elements */87 struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE];88 89 /* Do reset or abort function. */90 wait_queue_head_t wq_reset; /* reset work queue */91 int wait_reset; /* reset work queue condition */92 int32_t rslt_reset; /* reset response status: */93 /* SUCCESS or FAILED or: */94#define RSLT_RESET_WAITING 095#define RSLT_RESET_ERR -196 97 /* Requested struct scsi_cmnd is stored from kernel. */98 struct scsi_cmnd *sc;99 int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL];100};101 102struct vscsifrnt_info {103 struct xenbus_device *dev;104 105 struct Scsi_Host *host;106 enum {107 STATE_INACTIVE,108 STATE_ACTIVE,109 STATE_ERROR110 } host_active;111 112 unsigned int evtchn;113 unsigned int irq;114 115 grant_ref_t ring_ref;116 struct vscsiif_front_ring ring;117 struct vscsiif_response ring_rsp;118 119 spinlock_t shadow_lock;120 DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS);121 struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS];122 123 /* Following items are protected by the host lock. */124 wait_queue_head_t wq_sync;125 wait_queue_head_t wq_pause;126 unsigned int wait_ring_available:1;127 unsigned int waiting_pause:1;128 unsigned int pause:1;129 unsigned callers;130 131 char dev_state_path[64];132 struct task_struct *curr;133};134 135static DEFINE_MUTEX(scsifront_mutex);136 137static void scsifront_wake_up(struct vscsifrnt_info *info)138{139 info->wait_ring_available = 0;140 wake_up(&info->wq_sync);141}142 143static int scsifront_get_rqid(struct vscsifrnt_info *info)144{145 unsigned long flags;146 int free;147 148 spin_lock_irqsave(&info->shadow_lock, flags);149 150 free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);151 __clear_bit(free, info->shadow_free_bitmap);152 153 spin_unlock_irqrestore(&info->shadow_lock, flags);154 155 return free;156}157 158static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)159{160 int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);161 162 __set_bit(id, info->shadow_free_bitmap);163 info->shadow[id] = NULL;164 165 return empty || info->wait_ring_available;166}167 168static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)169{170 unsigned long flags;171 int kick;172 173 spin_lock_irqsave(&info->shadow_lock, flags);174 kick = _scsifront_put_rqid(info, id);175 spin_unlock_irqrestore(&info->shadow_lock, flags);176 177 if (kick)178 scsifront_wake_up(info);179}180 181static int scsifront_do_request(struct vscsifrnt_info *info,182 struct vscsifrnt_shadow *shadow)183{184 struct vscsiif_front_ring *ring = &(info->ring);185 struct vscsiif_request *ring_req;186 struct scsi_cmnd *sc = shadow->sc;187 uint32_t id;188 int i, notify;189 190 if (RING_FULL(&info->ring))191 return -EBUSY;192 193 id = scsifront_get_rqid(info); /* use id in response */194 if (id >= VSCSIIF_MAX_REQS)195 return -EBUSY;196 197 info->shadow[id] = shadow;198 shadow->rqid = id;199 200 ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt);201 ring->req_prod_pvt++;202 203 ring_req->rqid = id;204 ring_req->act = shadow->act;205 ring_req->ref_rqid = shadow->ref_rqid;206 ring_req->nr_segments = shadow->nr_segments;207 208 ring_req->id = sc->device->id;209 ring_req->lun = sc->device->lun;210 ring_req->channel = sc->device->channel;211 ring_req->cmd_len = sc->cmd_len;212 213 BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE);214 215 memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len);216 217 ring_req->sc_data_direction = (uint8_t)sc->sc_data_direction;218 ring_req->timeout_per_command = scsi_cmd_to_rq(sc)->timeout / HZ;219 220 for (i = 0; i < (shadow->nr_segments & ~VSCSIIF_SG_GRANT); i++)221 ring_req->seg[i] = shadow->seg[i];222 223 shadow->inflight = true;224 225 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify);226 if (notify)227 notify_remote_via_irq(info->irq);228 229 return 0;230}231 232static void scsifront_set_error(struct vscsifrnt_info *info, const char *msg)233{234 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME "%s\n"235 "Disabling device for further use\n", msg);236 info->host_active = STATE_ERROR;237}238 239static void scsifront_gnttab_done(struct vscsifrnt_info *info,240 struct vscsifrnt_shadow *shadow)241{242 int i;243 244 if (shadow->sc->sc_data_direction == DMA_NONE)245 return;246 247 for (i = 0; i < shadow->nr_grants; i++) {248 if (unlikely(!gnttab_try_end_foreign_access(shadow->gref[i]))) {249 scsifront_set_error(info, "grant still in use by backend");250 return;251 }252 }253 254 kfree(shadow->sg);255}256 257static unsigned int scsifront_host_byte(int32_t rslt)258{259 switch (XEN_VSCSIIF_RSLT_HOST(rslt)) {260 case XEN_VSCSIIF_RSLT_HOST_OK:261 return DID_OK;262 case XEN_VSCSIIF_RSLT_HOST_NO_CONNECT:263 return DID_NO_CONNECT;264 case XEN_VSCSIIF_RSLT_HOST_BUS_BUSY:265 return DID_BUS_BUSY;266 case XEN_VSCSIIF_RSLT_HOST_TIME_OUT:267 return DID_TIME_OUT;268 case XEN_VSCSIIF_RSLT_HOST_BAD_TARGET:269 return DID_BAD_TARGET;270 case XEN_VSCSIIF_RSLT_HOST_ABORT:271 return DID_ABORT;272 case XEN_VSCSIIF_RSLT_HOST_PARITY:273 return DID_PARITY;274 case XEN_VSCSIIF_RSLT_HOST_ERROR:275 return DID_ERROR;276 case XEN_VSCSIIF_RSLT_HOST_RESET:277 return DID_RESET;278 case XEN_VSCSIIF_RSLT_HOST_BAD_INTR:279 return DID_BAD_INTR;280 case XEN_VSCSIIF_RSLT_HOST_PASSTHROUGH:281 return DID_PASSTHROUGH;282 case XEN_VSCSIIF_RSLT_HOST_SOFT_ERROR:283 return DID_SOFT_ERROR;284 case XEN_VSCSIIF_RSLT_HOST_IMM_RETRY:285 return DID_IMM_RETRY;286 case XEN_VSCSIIF_RSLT_HOST_REQUEUE:287 return DID_REQUEUE;288 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_DISRUPTED:289 return DID_TRANSPORT_DISRUPTED;290 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_FAILFAST:291 return DID_TRANSPORT_FAILFAST;292 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_MARGINAL:293 return DID_TRANSPORT_MARGINAL;294 default:295 return DID_ERROR;296 }297}298 299static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info,300 struct vscsiif_response *ring_rsp)301{302 struct vscsifrnt_shadow *shadow;303 struct scsi_cmnd *sc;304 uint32_t id;305 uint8_t sense_len;306 307 id = ring_rsp->rqid;308 shadow = info->shadow[id];309 sc = shadow->sc;310 311 BUG_ON(sc == NULL);312 313 scsifront_gnttab_done(info, shadow);314 if (info->host_active == STATE_ERROR)315 return;316 scsifront_put_rqid(info, id);317 318 set_host_byte(sc, scsifront_host_byte(ring_rsp->rslt));319 set_status_byte(sc, XEN_VSCSIIF_RSLT_STATUS(ring_rsp->rslt));320 scsi_set_resid(sc, ring_rsp->residual_len);321 322 sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE,323 ring_rsp->sense_len);324 325 if (sense_len)326 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len);327 328 scsi_done(sc);329}330 331static void scsifront_sync_cmd_done(struct vscsifrnt_info *info,332 struct vscsiif_response *ring_rsp)333{334 uint16_t id = ring_rsp->rqid;335 unsigned long flags;336 struct vscsifrnt_shadow *shadow = info->shadow[id];337 int kick;338 339 spin_lock_irqsave(&info->shadow_lock, flags);340 shadow->wait_reset = 1;341 switch (shadow->rslt_reset) {342 case RSLT_RESET_WAITING:343 if (ring_rsp->rslt == XEN_VSCSIIF_RSLT_RESET_SUCCESS)344 shadow->rslt_reset = SUCCESS;345 else346 shadow->rslt_reset = FAILED;347 break;348 case RSLT_RESET_ERR:349 kick = _scsifront_put_rqid(info, id);350 spin_unlock_irqrestore(&info->shadow_lock, flags);351 kfree(shadow);352 if (kick)353 scsifront_wake_up(info);354 return;355 default:356 scsifront_set_error(info, "bad reset state");357 break;358 }359 spin_unlock_irqrestore(&info->shadow_lock, flags);360 361 wake_up(&shadow->wq_reset);362}363 364static void scsifront_do_response(struct vscsifrnt_info *info,365 struct vscsiif_response *ring_rsp)366{367 struct vscsifrnt_shadow *shadow;368 369 if (ring_rsp->rqid >= VSCSIIF_MAX_REQS ||370 !info->shadow[ring_rsp->rqid]->inflight) {371 scsifront_set_error(info, "illegal rqid returned by backend!");372 return;373 }374 shadow = info->shadow[ring_rsp->rqid];375 shadow->inflight = false;376 377 if (shadow->act == VSCSIIF_ACT_SCSI_CDB)378 scsifront_cdb_cmd_done(info, ring_rsp);379 else380 scsifront_sync_cmd_done(info, ring_rsp);381}382 383static int scsifront_ring_drain(struct vscsifrnt_info *info,384 unsigned int *eoiflag)385{386 struct vscsiif_response ring_rsp;387 RING_IDX i, rp;388 int more_to_do = 0;389 390 rp = READ_ONCE(info->ring.sring->rsp_prod);391 virt_rmb(); /* ordering required respective to backend */392 if (RING_RESPONSE_PROD_OVERFLOW(&info->ring, rp)) {393 scsifront_set_error(info, "illegal number of responses");394 return 0;395 }396 for (i = info->ring.rsp_cons; i != rp; i++) {397 RING_COPY_RESPONSE(&info->ring, i, &ring_rsp);398 scsifront_do_response(info, &ring_rsp);399 if (info->host_active == STATE_ERROR)400 return 0;401 *eoiflag &= ~XEN_EOI_FLAG_SPURIOUS;402 }403 404 info->ring.rsp_cons = i;405 406 if (i != info->ring.req_prod_pvt)407 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);408 else409 info->ring.sring->rsp_event = i + 1;410 411 return more_to_do;412}413 414static int scsifront_cmd_done(struct vscsifrnt_info *info,415 unsigned int *eoiflag)416{417 int more_to_do;418 unsigned long flags;419 420 spin_lock_irqsave(info->host->host_lock, flags);421 422 more_to_do = scsifront_ring_drain(info, eoiflag);423 424 info->wait_ring_available = 0;425 426 spin_unlock_irqrestore(info->host->host_lock, flags);427 428 wake_up(&info->wq_sync);429 430 return more_to_do;431}432 433static irqreturn_t scsifront_irq_fn(int irq, void *dev_id)434{435 struct vscsifrnt_info *info = dev_id;436 unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS;437 438 if (info->host_active == STATE_ERROR) {439 xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);440 return IRQ_HANDLED;441 }442 443 while (scsifront_cmd_done(info, &eoiflag))444 /* Yield point for this unbounded loop. */445 cond_resched();446 447 xen_irq_lateeoi(irq, eoiflag);448 449 return IRQ_HANDLED;450}451 452static void scsifront_finish_all(struct vscsifrnt_info *info)453{454 unsigned int i, dummy;455 struct vscsiif_response resp;456 457 scsifront_ring_drain(info, &dummy);458 459 for (i = 0; i < VSCSIIF_MAX_REQS; i++) {460 if (test_bit(i, info->shadow_free_bitmap))461 continue;462 resp.rqid = i;463 resp.sense_len = 0;464 resp.rslt = DID_RESET << 16;465 resp.residual_len = 0;466 scsifront_do_response(info, &resp);467 }468}469 470static int map_data_for_request(struct vscsifrnt_info *info,471 struct scsi_cmnd *sc,472 struct vscsifrnt_shadow *shadow)473{474 grant_ref_t gref_head;475 struct page *page;476 int err, ref, ref_cnt = 0;477 int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE);478 unsigned int i, off, len, bytes;479 unsigned int data_len = scsi_bufflen(sc);480 unsigned int data_grants = 0, seg_grants = 0;481 struct scatterlist *sg;482 struct scsiif_request_segment *seg;483 484 if (sc->sc_data_direction == DMA_NONE || !data_len)485 return 0;486 487 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)488 data_grants += PFN_UP(sg->offset + sg->length);489 490 if (data_grants > VSCSIIF_SG_TABLESIZE) {491 if (data_grants > info->host->sg_tablesize) {492 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME493 "Unable to map request_buffer for command!\n");494 return -E2BIG;495 }496 seg_grants = vscsiif_grants_sg(data_grants);497 shadow->sg = kcalloc(data_grants,498 sizeof(struct scsiif_request_segment), GFP_ATOMIC);499 if (!shadow->sg)500 return -ENOMEM;501 }502 seg = shadow->sg ? : shadow->seg;503 504 err = gnttab_alloc_grant_references(seg_grants + data_grants,505 &gref_head);506 if (err) {507 kfree(shadow->sg);508 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME509 "gnttab_alloc_grant_references() error\n");510 return -ENOMEM;511 }512 513 if (seg_grants) {514 page = virt_to_page(seg);515 off = offset_in_page(seg);516 len = sizeof(struct scsiif_request_segment) * data_grants;517 while (len > 0) {518 bytes = min_t(unsigned int, len, PAGE_SIZE - off);519 520 ref = gnttab_claim_grant_reference(&gref_head);521 BUG_ON(ref == -ENOSPC);522 523 gnttab_grant_foreign_access_ref(ref,524 info->dev->otherend_id,525 xen_page_to_gfn(page), 1);526 shadow->gref[ref_cnt] = ref;527 shadow->seg[ref_cnt].gref = ref;528 shadow->seg[ref_cnt].offset = (uint16_t)off;529 shadow->seg[ref_cnt].length = (uint16_t)bytes;530 531 page++;532 len -= bytes;533 off = 0;534 ref_cnt++;535 }536 BUG_ON(seg_grants < ref_cnt);537 seg_grants = ref_cnt;538 }539 540 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {541 page = sg_page(sg);542 off = sg->offset;543 len = sg->length;544 545 while (len > 0 && data_len > 0) {546 /*547 * sg sends a scatterlist that is larger than548 * the data_len it wants transferred for certain549 * IO sizes.550 */551 bytes = min_t(unsigned int, len, PAGE_SIZE - off);552 bytes = min(bytes, data_len);553 554 ref = gnttab_claim_grant_reference(&gref_head);555 BUG_ON(ref == -ENOSPC);556 557 gnttab_grant_foreign_access_ref(ref,558 info->dev->otherend_id,559 xen_page_to_gfn(page),560 grant_ro);561 562 shadow->gref[ref_cnt] = ref;563 seg->gref = ref;564 seg->offset = (uint16_t)off;565 seg->length = (uint16_t)bytes;566 567 page++;568 seg++;569 len -= bytes;570 data_len -= bytes;571 off = 0;572 ref_cnt++;573 }574 }575 576 if (seg_grants)577 shadow->nr_segments = VSCSIIF_SG_GRANT | seg_grants;578 else579 shadow->nr_segments = (uint8_t)ref_cnt;580 shadow->nr_grants = ref_cnt;581 582 return 0;583}584 585static int scsifront_enter(struct vscsifrnt_info *info)586{587 if (info->pause)588 return 1;589 info->callers++;590 return 0;591}592 593static void scsifront_return(struct vscsifrnt_info *info)594{595 info->callers--;596 if (info->callers)597 return;598 599 if (!info->waiting_pause)600 return;601 602 info->waiting_pause = 0;603 wake_up(&info->wq_pause);604}605 606static int scsifront_queuecommand(struct Scsi_Host *shost,607 struct scsi_cmnd *sc)608{609 struct vscsifrnt_info *info = shost_priv(shost);610 struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc);611 unsigned long flags;612 int err;613 614 if (info->host_active == STATE_ERROR)615 return SCSI_MLQUEUE_HOST_BUSY;616 617 sc->result = 0;618 619 shadow->sc = sc;620 shadow->act = VSCSIIF_ACT_SCSI_CDB;621 622 spin_lock_irqsave(shost->host_lock, flags);623 if (scsifront_enter(info)) {624 spin_unlock_irqrestore(shost->host_lock, flags);625 return SCSI_MLQUEUE_HOST_BUSY;626 }627 628 err = map_data_for_request(info, sc, shadow);629 if (err < 0) {630 pr_debug("%s: err %d\n", __func__, err);631 scsifront_return(info);632 spin_unlock_irqrestore(shost->host_lock, flags);633 if (err == -ENOMEM)634 return SCSI_MLQUEUE_HOST_BUSY;635 sc->result = DID_ERROR << 16;636 scsi_done(sc);637 return 0;638 }639 640 if (scsifront_do_request(info, shadow)) {641 scsifront_gnttab_done(info, shadow);642 goto busy;643 }644 645 scsifront_return(info);646 spin_unlock_irqrestore(shost->host_lock, flags);647 648 return 0;649 650busy:651 scsifront_return(info);652 spin_unlock_irqrestore(shost->host_lock, flags);653 pr_debug("%s: busy\n", __func__);654 return SCSI_MLQUEUE_HOST_BUSY;655}656 657/*658 * Any exception handling (reset or abort) must be forwarded to the backend.659 * We have to wait until an answer is returned. This answer contains the660 * result to be returned to the requestor.661 */662static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)663{664 struct Scsi_Host *host = sc->device->host;665 struct vscsifrnt_info *info = shost_priv(host);666 struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);667 int err = 0;668 669 if (info->host_active == STATE_ERROR)670 return FAILED;671 672 shadow = kzalloc(sizeof(*shadow), GFP_NOIO);673 if (!shadow)674 return FAILED;675 676 shadow->act = act;677 shadow->rslt_reset = RSLT_RESET_WAITING;678 shadow->sc = sc;679 shadow->ref_rqid = s->rqid;680 init_waitqueue_head(&shadow->wq_reset);681 682 spin_lock_irq(host->host_lock);683 684 for (;;) {685 if (scsifront_enter(info))686 goto fail;687 688 if (!scsifront_do_request(info, shadow))689 break;690 691 scsifront_return(info);692 if (err)693 goto fail;694 info->wait_ring_available = 1;695 spin_unlock_irq(host->host_lock);696 err = wait_event_interruptible(info->wq_sync,697 !info->wait_ring_available);698 spin_lock_irq(host->host_lock);699 }700 701 spin_unlock_irq(host->host_lock);702 err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);703 spin_lock_irq(host->host_lock);704 705 if (!err) {706 err = shadow->rslt_reset;707 scsifront_put_rqid(info, shadow->rqid);708 kfree(shadow);709 } else {710 spin_lock(&info->shadow_lock);711 shadow->rslt_reset = RSLT_RESET_ERR;712 spin_unlock(&info->shadow_lock);713 err = FAILED;714 }715 716 scsifront_return(info);717 spin_unlock_irq(host->host_lock);718 return err;719 720fail:721 spin_unlock_irq(host->host_lock);722 kfree(shadow);723 return FAILED;724}725 726static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)727{728 pr_debug("%s\n", __func__);729 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);730}731 732static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)733{734 pr_debug("%s\n", __func__);735 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);736}737 738static int scsifront_sdev_configure(struct scsi_device *sdev)739{740 struct vscsifrnt_info *info = shost_priv(sdev->host);741 int err;742 743 if (info->host_active == STATE_ERROR)744 return -EIO;745 746 if (current == info->curr) {747 err = xenbus_printf(XBT_NIL, info->dev->nodename,748 info->dev_state_path, "%d", XenbusStateConnected);749 if (err) {750 xenbus_dev_error(info->dev, err,751 "%s: writing dev_state_path", __func__);752 return err;753 }754 }755 756 return 0;757}758 759static void scsifront_sdev_destroy(struct scsi_device *sdev)760{761 struct vscsifrnt_info *info = shost_priv(sdev->host);762 int err;763 764 if (current == info->curr) {765 err = xenbus_printf(XBT_NIL, info->dev->nodename,766 info->dev_state_path, "%d", XenbusStateClosed);767 if (err)768 xenbus_dev_error(info->dev, err,769 "%s: writing dev_state_path", __func__);770 }771}772 773static const struct scsi_host_template scsifront_sht = {774 .module = THIS_MODULE,775 .name = "Xen SCSI frontend driver",776 .queuecommand = scsifront_queuecommand,777 .eh_abort_handler = scsifront_eh_abort_handler,778 .eh_device_reset_handler = scsifront_dev_reset_handler,779 .slave_configure = scsifront_sdev_configure,780 .slave_destroy = scsifront_sdev_destroy,781 .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN,782 .can_queue = VSCSIIF_MAX_REQS,783 .this_id = -1,784 .cmd_size = sizeof(struct vscsifrnt_shadow),785 .sg_tablesize = VSCSIIF_SG_TABLESIZE,786 .proc_name = "scsifront",787};788 789static int scsifront_alloc_ring(struct vscsifrnt_info *info)790{791 struct xenbus_device *dev = info->dev;792 struct vscsiif_sring *sring;793 int err;794 795 /***** Frontend to Backend ring start *****/796 err = xenbus_setup_ring(dev, GFP_KERNEL, (void **)&sring, 1,797 &info->ring_ref);798 if (err)799 return err;800 801 XEN_FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);802 803 err = xenbus_alloc_evtchn(dev, &info->evtchn);804 if (err) {805 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");806 goto free_gnttab;807 }808 809 err = bind_evtchn_to_irq_lateeoi(info->evtchn);810 if (err <= 0) {811 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");812 goto free_gnttab;813 }814 815 info->irq = err;816 817 err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,818 IRQF_ONESHOT, "scsifront", info);819 if (err) {820 xenbus_dev_fatal(dev, err, "request_threaded_irq");821 goto free_irq;822 }823 824 return 0;825 826/* free resource */827free_irq:828 unbind_from_irqhandler(info->irq, info);829free_gnttab:830 xenbus_teardown_ring((void **)&sring, 1, &info->ring_ref);831 832 return err;833}834 835static void scsifront_free_ring(struct vscsifrnt_info *info)836{837 unbind_from_irqhandler(info->irq, info);838 xenbus_teardown_ring((void **)&info->ring.sring, 1, &info->ring_ref);839}840 841static int scsifront_init_ring(struct vscsifrnt_info *info)842{843 struct xenbus_device *dev = info->dev;844 struct xenbus_transaction xbt;845 int err;846 847 pr_debug("%s\n", __func__);848 849 err = scsifront_alloc_ring(info);850 if (err)851 return err;852 pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);853 854again:855 err = xenbus_transaction_start(&xbt);856 if (err)857 xenbus_dev_fatal(dev, err, "starting transaction");858 859 err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",860 info->ring_ref);861 if (err) {862 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");863 goto fail;864 }865 866 err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",867 info->evtchn);868 869 if (err) {870 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");871 goto fail;872 }873 874 err = xenbus_transaction_end(xbt, 0);875 if (err) {876 if (err == -EAGAIN)877 goto again;878 xenbus_dev_fatal(dev, err, "completing transaction");879 goto free_sring;880 }881 882 return 0;883 884fail:885 xenbus_transaction_end(xbt, 1);886free_sring:887 scsifront_free_ring(info);888 889 return err;890}891 892 893static int scsifront_probe(struct xenbus_device *dev,894 const struct xenbus_device_id *id)895{896 struct vscsifrnt_info *info;897 struct Scsi_Host *host;898 int err = -ENOMEM;899 char name[TASK_COMM_LEN];900 901 host = scsi_host_alloc(&scsifront_sht, sizeof(*info));902 if (!host) {903 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");904 return err;905 }906 info = shost_priv(host);907 908 dev_set_drvdata(&dev->dev, info);909 info->dev = dev;910 911 bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);912 913 err = scsifront_init_ring(info);914 if (err) {915 scsi_host_put(host);916 return err;917 }918 919 init_waitqueue_head(&info->wq_sync);920 init_waitqueue_head(&info->wq_pause);921 spin_lock_init(&info->shadow_lock);922 923 snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);924 925 host->max_id = VSCSIIF_MAX_TARGET;926 host->max_channel = 0;927 host->max_lun = VSCSIIF_MAX_LUN;928 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;929 host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;930 931 err = scsi_add_host(host, &dev->dev);932 if (err) {933 dev_err(&dev->dev, "fail to add scsi host %d\n", err);934 goto free_sring;935 }936 info->host = host;937 info->host_active = STATE_ACTIVE;938 939 xenbus_switch_state(dev, XenbusStateInitialised);940 941 return 0;942 943free_sring:944 scsifront_free_ring(info);945 scsi_host_put(host);946 return err;947}948 949static int scsifront_resume(struct xenbus_device *dev)950{951 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);952 struct Scsi_Host *host = info->host;953 int err;954 955 spin_lock_irq(host->host_lock);956 957 /* Finish all still pending commands. */958 scsifront_finish_all(info);959 960 spin_unlock_irq(host->host_lock);961 962 /* Reconnect to dom0. */963 scsifront_free_ring(info);964 err = scsifront_init_ring(info);965 if (err) {966 dev_err(&dev->dev, "fail to resume %d\n", err);967 scsi_host_put(host);968 return err;969 }970 971 xenbus_switch_state(dev, XenbusStateInitialised);972 973 return 0;974}975 976static int scsifront_suspend(struct xenbus_device *dev)977{978 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);979 struct Scsi_Host *host = info->host;980 int err = 0;981 982 /* No new commands for the backend. */983 spin_lock_irq(host->host_lock);984 info->pause = 1;985 while (info->callers && !err) {986 info->waiting_pause = 1;987 info->wait_ring_available = 0;988 spin_unlock_irq(host->host_lock);989 wake_up(&info->wq_sync);990 err = wait_event_interruptible(info->wq_pause,991 !info->waiting_pause);992 spin_lock_irq(host->host_lock);993 }994 spin_unlock_irq(host->host_lock);995 return err;996}997 998static void scsifront_remove(struct xenbus_device *dev)999{1000 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);1001 1002 pr_debug("%s: %s removed\n", __func__, dev->nodename);1003 1004 mutex_lock(&scsifront_mutex);1005 if (info->host_active != STATE_INACTIVE) {1006 /* Scsi_host not yet removed */1007 scsi_remove_host(info->host);1008 info->host_active = STATE_INACTIVE;1009 }1010 mutex_unlock(&scsifront_mutex);1011 1012 scsifront_free_ring(info);1013 scsi_host_put(info->host);1014}1015 1016static void scsifront_disconnect(struct vscsifrnt_info *info)1017{1018 struct xenbus_device *dev = info->dev;1019 struct Scsi_Host *host = info->host;1020 1021 pr_debug("%s: %s disconnect\n", __func__, dev->nodename);1022 1023 /*1024 * When this function is executed, all devices of1025 * Frontend have been deleted.1026 * Therefore, it need not block I/O before remove_host.1027 */1028 1029 mutex_lock(&scsifront_mutex);1030 if (info->host_active != STATE_INACTIVE) {1031 scsi_remove_host(host);1032 info->host_active = STATE_INACTIVE;1033 }1034 mutex_unlock(&scsifront_mutex);1035 1036 xenbus_frontend_closed(dev);1037}1038 1039static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)1040{1041 struct xenbus_device *dev = info->dev;1042 int i, err = 0;1043 char str[64];1044 char **dir;1045 unsigned int dir_n = 0;1046 unsigned int device_state;1047 unsigned int hst, chn, tgt, lun;1048 struct scsi_device *sdev;1049 1050 if (info->host_active == STATE_ERROR)1051 return;1052 1053 dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);1054 if (IS_ERR(dir))1055 return;1056 1057 /* mark current task as the one allowed to modify device states */1058 BUG_ON(info->curr);1059 info->curr = current;1060 1061 for (i = 0; i < dir_n; i++) {1062 /* read status */1063 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);1064 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",1065 &device_state);1066 if (XENBUS_EXIST_ERR(err))1067 continue;1068 1069 /* virtual SCSI device */1070 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);1071 err = xenbus_scanf(XBT_NIL, dev->otherend, str,1072 "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);1073 if (XENBUS_EXIST_ERR(err))1074 continue;1075 1076 /*1077 * Front device state path, used in slave_configure called1078 * on successfull scsi_add_device, and in slave_destroy called1079 * on remove of a device.1080 */1081 snprintf(info->dev_state_path, sizeof(info->dev_state_path),1082 "vscsi-devs/%s/state", dir[i]);1083 1084 switch (op) {1085 case VSCSIFRONT_OP_ADD_LUN:1086 if (device_state != XenbusStateInitialised)1087 break;1088 1089 if (scsi_add_device(info->host, chn, tgt, lun)) {1090 dev_err(&dev->dev, "scsi_add_device\n");1091 err = xenbus_printf(XBT_NIL, dev->nodename,1092 info->dev_state_path,1093 "%d", XenbusStateClosed);1094 if (err)1095 xenbus_dev_error(dev, err,1096 "%s: writing dev_state_path", __func__);1097 }1098 break;1099 case VSCSIFRONT_OP_DEL_LUN:1100 if (device_state != XenbusStateClosing)1101 break;1102 1103 sdev = scsi_device_lookup(info->host, chn, tgt, lun);1104 if (sdev) {1105 scsi_remove_device(sdev);1106 scsi_device_put(sdev);1107 }1108 break;1109 case VSCSIFRONT_OP_READD_LUN:1110 if (device_state == XenbusStateConnected) {1111 err = xenbus_printf(XBT_NIL, dev->nodename,1112 info->dev_state_path,1113 "%d", XenbusStateConnected);1114 if (err)1115 xenbus_dev_error(dev, err,1116 "%s: writing dev_state_path", __func__);1117 }1118 break;1119 default:1120 break;1121 }1122 }1123 1124 info->curr = NULL;1125 1126 kfree(dir);1127}1128 1129static void scsifront_read_backend_params(struct xenbus_device *dev,1130 struct vscsifrnt_info *info)1131{1132 unsigned int sg_grant, nr_segs;1133 struct Scsi_Host *host = info->host;1134 1135 sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0);1136 nr_segs = min_t(unsigned int, sg_grant, SG_ALL);1137 nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);1138 nr_segs = min_t(unsigned int, nr_segs,1139 VSCSIIF_SG_TABLESIZE * PAGE_SIZE /1140 sizeof(struct scsiif_request_segment));1141 1142 if (!info->pause && sg_grant)1143 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);1144 else if (info->pause && nr_segs < host->sg_tablesize)1145 dev_warn(&dev->dev,1146 "SG entries decreased from %d to %u - device may not work properly anymore\n",1147 host->sg_tablesize, nr_segs);1148 1149 host->sg_tablesize = nr_segs;1150 host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;1151}1152 1153static void scsifront_backend_changed(struct xenbus_device *dev,1154 enum xenbus_state backend_state)1155{1156 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);1157 1158 pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);1159 1160 switch (backend_state) {1161 case XenbusStateUnknown:1162 case XenbusStateInitialising:1163 case XenbusStateInitWait:1164 case XenbusStateInitialised:1165 break;1166 1167 case XenbusStateConnected:1168 scsifront_read_backend_params(dev, info);1169 1170 if (info->pause) {1171 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);1172 xenbus_switch_state(dev, XenbusStateConnected);1173 info->pause = 0;1174 return;1175 }1176 1177 if (xenbus_read_driver_state(dev->nodename) ==1178 XenbusStateInitialised)1179 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);1180 1181 if (dev->state != XenbusStateConnected)1182 xenbus_switch_state(dev, XenbusStateConnected);1183 break;1184 1185 case XenbusStateClosed:1186 if (dev->state == XenbusStateClosed)1187 break;1188 fallthrough; /* Missed the backend's Closing state */1189 case XenbusStateClosing:1190 scsifront_disconnect(info);1191 break;1192 1193 case XenbusStateReconfiguring:1194 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);1195 xenbus_switch_state(dev, XenbusStateReconfiguring);1196 break;1197 1198 case XenbusStateReconfigured:1199 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);1200 xenbus_switch_state(dev, XenbusStateConnected);1201 break;1202 }1203}1204 1205static const struct xenbus_device_id scsifront_ids[] = {1206 { "vscsi" },1207 { "" }1208};1209 1210static struct xenbus_driver scsifront_driver = {1211 .ids = scsifront_ids,1212 .probe = scsifront_probe,1213 .remove = scsifront_remove,1214 .resume = scsifront_resume,1215 .suspend = scsifront_suspend,1216 .otherend_changed = scsifront_backend_changed,1217};1218 1219static int __init scsifront_init(void)1220{1221 if (!xen_domain())1222 return -ENODEV;1223 1224 return xenbus_register_frontend(&scsifront_driver);1225}1226module_init(scsifront_init);1227 1228static void __exit scsifront_exit(void)1229{1230 xenbus_unregister_driver(&scsifront_driver);1231}1232module_exit(scsifront_exit);1233 1234MODULE_DESCRIPTION("Xen SCSI frontend driver");1235MODULE_LICENSE("GPL");1236MODULE_ALIAS("xen:vscsi");1237MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");1238