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	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
 103struct 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
 132static DEFINE_MUTEX(scsifront_mutex);
 133
 134static void scsifront_wake_up(struct vscsifrnt_info *info)
 135{
 136	info->wait_ring_available = 0;
 137	wake_up(&info->wq_sync);
 138}
 139
 140static 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
 155static 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
 165static 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
 178static 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
 227static 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
 247static 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
 276static 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
 308static 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
 322static 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
 345static 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
 363static 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
 374static 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
 392static 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
 507static int scsifront_enter(struct vscsifrnt_info *info)
 508{
 509	if (info->pause)
 510		return 1;
 511	info->callers++;
 512	return 0;
 513}
 514
 515static 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
 528static 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
 569busy:
 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 */
 581static 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
 636fail:
 637	spin_unlock_irq(host->host_lock);
 638	kfree(shadow);
 639	return FAILED;
 640}
 641
 642static 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
 648static 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
 654static int scsifront_sdev_configure(struct scsi_device *sdev)
 655{
 656	struct vscsifrnt_info *info = shost_priv(sdev->host);
 
 657
 658	if (info && current == info->curr)
 659		xenbus_printf(XBT_NIL, info->dev->nodename,
 660			      info->dev_state_path, "%d", XenbusStateConnected);
 
 
 
 
 
 
 661
 662	return 0;
 663}
 664
 665static void scsifront_sdev_destroy(struct scsi_device *sdev)
 666{
 667	struct vscsifrnt_info *info = shost_priv(sdev->host);
 
 668
 669	if (info && current == info->curr)
 670		xenbus_printf(XBT_NIL, info->dev->nodename,
 671			      info->dev_state_path, "%d", XenbusStateClosed);
 
 
 
 
 672}
 673
 674static struct scsi_host_template scsifront_sht = {
 675	.module			= THIS_MODULE,
 676	.name			= "Xen SCSI frontend driver",
 677	.queuecommand		= scsifront_queuecommand,
 678	.eh_abort_handler	= scsifront_eh_abort_handler,
 679	.eh_device_reset_handler = scsifront_dev_reset_handler,
 680	.slave_configure	= scsifront_sdev_configure,
 681	.slave_destroy		= scsifront_sdev_destroy,
 682	.cmd_per_lun		= VSCSIIF_DEFAULT_CMD_PER_LUN,
 683	.can_queue		= VSCSIIF_MAX_REQS,
 684	.this_id		= -1,
 685	.cmd_size		= sizeof(struct vscsifrnt_shadow),
 686	.sg_tablesize		= VSCSIIF_SG_TABLESIZE,
 687	.use_clustering		= DISABLE_CLUSTERING,
 688	.proc_name		= "scsifront",
 689};
 690
 691static int scsifront_alloc_ring(struct vscsifrnt_info *info)
 692{
 693	struct xenbus_device *dev = info->dev;
 694	struct vscsiif_sring *sring;
 695	grant_ref_t gref;
 696	int err = -ENOMEM;
 697
 698	/***** Frontend to Backend ring start *****/
 699	sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL);
 700	if (!sring) {
 701		xenbus_dev_fatal(dev, err,
 702			"fail to allocate shared ring (Front to Back)");
 703		return err;
 704	}
 705	SHARED_RING_INIT(sring);
 706	FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 707
 708	err = xenbus_grant_ring(dev, sring, 1, &gref);
 709	if (err < 0) {
 710		free_page((unsigned long)sring);
 711		xenbus_dev_fatal(dev, err,
 712			"fail to grant shared ring (Front to Back)");
 713		return err;
 714	}
 715	info->ring_ref = gref;
 716
 717	err = xenbus_alloc_evtchn(dev, &info->evtchn);
 718	if (err) {
 719		xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
 720		goto free_gnttab;
 721	}
 722
 723	err = bind_evtchn_to_irq(info->evtchn);
 724	if (err <= 0) {
 725		xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
 726		goto free_gnttab;
 727	}
 728
 729	info->irq = err;
 730
 731	err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
 732				   IRQF_ONESHOT, "scsifront", info);
 733	if (err) {
 734		xenbus_dev_fatal(dev, err, "request_threaded_irq");
 735		goto free_irq;
 736	}
 737
 738	return 0;
 739
 740/* free resource */
 741free_irq:
 742	unbind_from_irqhandler(info->irq, info);
 743free_gnttab:
 744	gnttab_end_foreign_access(info->ring_ref, 0,
 745				  (unsigned long)info->ring.sring);
 746
 747	return err;
 748}
 749
 750static void scsifront_free_ring(struct vscsifrnt_info *info)
 751{
 752	unbind_from_irqhandler(info->irq, info);
 753	gnttab_end_foreign_access(info->ring_ref, 0,
 754				  (unsigned long)info->ring.sring);
 755}
 756
 757static int scsifront_init_ring(struct vscsifrnt_info *info)
 758{
 759	struct xenbus_device *dev = info->dev;
 760	struct xenbus_transaction xbt;
 761	int err;
 762
 763	pr_debug("%s\n", __func__);
 764
 765	err = scsifront_alloc_ring(info);
 766	if (err)
 767		return err;
 768	pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
 769
 770again:
 771	err = xenbus_transaction_start(&xbt);
 772	if (err)
 773		xenbus_dev_fatal(dev, err, "starting transaction");
 774
 775	err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
 776			    info->ring_ref);
 777	if (err) {
 778		xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
 779		goto fail;
 780	}
 781
 782	err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
 783			    info->evtchn);
 784
 785	if (err) {
 786		xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
 787		goto fail;
 788	}
 789
 790	err = xenbus_transaction_end(xbt, 0);
 791	if (err) {
 792		if (err == -EAGAIN)
 793			goto again;
 794		xenbus_dev_fatal(dev, err, "completing transaction");
 795		goto free_sring;
 796	}
 797
 798	return 0;
 799
 800fail:
 801	xenbus_transaction_end(xbt, 1);
 802free_sring:
 803	scsifront_free_ring(info);
 804
 805	return err;
 806}
 807
 808
 809static int scsifront_probe(struct xenbus_device *dev,
 810			   const struct xenbus_device_id *id)
 811{
 812	struct vscsifrnt_info *info;
 813	struct Scsi_Host *host;
 814	int err = -ENOMEM;
 815	char name[TASK_COMM_LEN];
 816
 817	host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
 818	if (!host) {
 819		xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
 820		return err;
 821	}
 822	info = (struct vscsifrnt_info *)host->hostdata;
 823
 824	dev_set_drvdata(&dev->dev, info);
 825	info->dev = dev;
 826
 827	bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
 828
 829	err = scsifront_init_ring(info);
 830	if (err) {
 831		scsi_host_put(host);
 832		return err;
 833	}
 834
 835	init_waitqueue_head(&info->wq_sync);
 836	init_waitqueue_head(&info->wq_pause);
 837	spin_lock_init(&info->shadow_lock);
 838
 839	snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
 840
 841	host->max_id      = VSCSIIF_MAX_TARGET;
 842	host->max_channel = 0;
 843	host->max_lun     = VSCSIIF_MAX_LUN;
 844	host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
 845	host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
 846
 847	err = scsi_add_host(host, &dev->dev);
 848	if (err) {
 849		dev_err(&dev->dev, "fail to add scsi host %d\n", err);
 850		goto free_sring;
 851	}
 852	info->host = host;
 853	info->host_active = 1;
 854
 855	xenbus_switch_state(dev, XenbusStateInitialised);
 856
 857	return 0;
 858
 859free_sring:
 860	scsifront_free_ring(info);
 861	scsi_host_put(host);
 862	return err;
 863}
 864
 865static int scsifront_resume(struct xenbus_device *dev)
 866{
 867	struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 868	struct Scsi_Host *host = info->host;
 869	int err;
 870
 871	spin_lock_irq(host->host_lock);
 872
 873	/* Finish all still pending commands. */
 874	scsifront_finish_all(info);
 875
 876	spin_unlock_irq(host->host_lock);
 877
 878	/* Reconnect to dom0. */
 879	scsifront_free_ring(info);
 880	err = scsifront_init_ring(info);
 881	if (err) {
 882		dev_err(&dev->dev, "fail to resume %d\n", err);
 883		scsi_host_put(host);
 884		return err;
 885	}
 886
 887	xenbus_switch_state(dev, XenbusStateInitialised);
 888
 889	return 0;
 890}
 891
 892static int scsifront_suspend(struct xenbus_device *dev)
 893{
 894	struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 895	struct Scsi_Host *host = info->host;
 896	int err = 0;
 897
 898	/* No new commands for the backend. */
 899	spin_lock_irq(host->host_lock);
 900	info->pause = 1;
 901	while (info->callers && !err) {
 902		info->waiting_pause = 1;
 903		info->wait_ring_available = 0;
 904		spin_unlock_irq(host->host_lock);
 905		wake_up(&info->wq_sync);
 906		err = wait_event_interruptible(info->wq_pause,
 907					       !info->waiting_pause);
 908		spin_lock_irq(host->host_lock);
 909	}
 910	spin_unlock_irq(host->host_lock);
 911	return err;
 912}
 913
 914static int scsifront_remove(struct xenbus_device *dev)
 915{
 916	struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
 917
 918	pr_debug("%s: %s removed\n", __func__, dev->nodename);
 919
 920	mutex_lock(&scsifront_mutex);
 921	if (info->host_active) {
 922		/* Scsi_host not yet removed */
 923		scsi_remove_host(info->host);
 924		info->host_active = 0;
 925	}
 926	mutex_unlock(&scsifront_mutex);
 927
 928	scsifront_free_ring(info);
 929	scsi_host_put(info->host);
 930
 931	return 0;
 932}
 933
 934static void scsifront_disconnect(struct vscsifrnt_info *info)
 935{
 936	struct xenbus_device *dev = info->dev;
 937	struct Scsi_Host *host = info->host;
 938
 939	pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
 940
 941	/*
 942	 * When this function is executed, all devices of
 943	 * Frontend have been deleted.
 944	 * Therefore, it need not block I/O before remove_host.
 945	 */
 946
 947	mutex_lock(&scsifront_mutex);
 948	if (info->host_active) {
 949		scsi_remove_host(host);
 950		info->host_active = 0;
 951	}
 952	mutex_unlock(&scsifront_mutex);
 953
 954	xenbus_frontend_closed(dev);
 955}
 956
 957static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
 958{
 959	struct xenbus_device *dev = info->dev;
 960	int i, err = 0;
 961	char str[64];
 962	char **dir;
 963	unsigned int dir_n = 0;
 964	unsigned int device_state;
 965	unsigned int hst, chn, tgt, lun;
 966	struct scsi_device *sdev;
 967
 968	dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
 969	if (IS_ERR(dir))
 970		return;
 971
 972	/* mark current task as the one allowed to modify device states */
 973	BUG_ON(info->curr);
 974	info->curr = current;
 975
 976	for (i = 0; i < dir_n; i++) {
 977		/* read status */
 978		snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
 979		err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
 980				   &device_state);
 981		if (XENBUS_EXIST_ERR(err))
 982			continue;
 983
 984		/* virtual SCSI device */
 985		snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
 986		err = xenbus_scanf(XBT_NIL, dev->otherend, str,
 987				   "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
 988		if (XENBUS_EXIST_ERR(err))
 989			continue;
 990
 991		/*
 992		 * Front device state path, used in slave_configure called
 993		 * on successfull scsi_add_device, and in slave_destroy called
 994		 * on remove of a device.
 995		 */
 996		snprintf(info->dev_state_path, sizeof(info->dev_state_path),
 997			 "vscsi-devs/%s/state", dir[i]);
 998
 999		switch (op) {
1000		case VSCSIFRONT_OP_ADD_LUN:
1001			if (device_state != XenbusStateInitialised)
1002				break;
1003
1004			if (scsi_add_device(info->host, chn, tgt, lun)) {
1005				dev_err(&dev->dev, "scsi_add_device\n");
1006				xenbus_printf(XBT_NIL, dev->nodename,
1007					      info->dev_state_path,
1008					      "%d", XenbusStateClosed);
 
 
 
1009			}
1010			break;
1011		case VSCSIFRONT_OP_DEL_LUN:
1012			if (device_state != XenbusStateClosing)
1013				break;
1014
1015			sdev = scsi_device_lookup(info->host, chn, tgt, lun);
1016			if (sdev) {
1017				scsi_remove_device(sdev);
1018				scsi_device_put(sdev);
1019			}
1020			break;
1021		case VSCSIFRONT_OP_READD_LUN:
1022			if (device_state == XenbusStateConnected)
1023				xenbus_printf(XBT_NIL, dev->nodename,
1024					      info->dev_state_path,
1025					      "%d", XenbusStateConnected);
 
 
 
 
1026			break;
1027		default:
1028			break;
1029		}
1030	}
1031
1032	info->curr = NULL;
1033
1034	kfree(dir);
1035}
1036
1037static void scsifront_read_backend_params(struct xenbus_device *dev,
1038					  struct vscsifrnt_info *info)
1039{
1040	unsigned int sg_grant, nr_segs;
1041	struct Scsi_Host *host = info->host;
1042
1043	sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0);
1044	nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
1045	nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
1046	nr_segs = min_t(unsigned int, nr_segs,
1047			VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
1048			sizeof(struct scsiif_request_segment));
1049
1050	if (!info->pause && sg_grant)
1051		dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);
1052	else if (info->pause && nr_segs < host->sg_tablesize)
1053		dev_warn(&dev->dev,
1054			 "SG entries decreased from %d to %u - device may not work properly anymore\n",
1055			 host->sg_tablesize, nr_segs);
1056
1057	host->sg_tablesize = nr_segs;
1058	host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;
1059}
1060
1061static void scsifront_backend_changed(struct xenbus_device *dev,
1062				      enum xenbus_state backend_state)
1063{
1064	struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1065
1066	pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
1067
1068	switch (backend_state) {
1069	case XenbusStateUnknown:
1070	case XenbusStateInitialising:
1071	case XenbusStateInitWait:
1072	case XenbusStateInitialised:
1073		break;
1074
1075	case XenbusStateConnected:
1076		scsifront_read_backend_params(dev, info);
1077
1078		if (info->pause) {
1079			scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);
1080			xenbus_switch_state(dev, XenbusStateConnected);
1081			info->pause = 0;
1082			return;
1083		}
1084
1085		if (xenbus_read_driver_state(dev->nodename) ==
1086		    XenbusStateInitialised)
1087			scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1088
1089		if (dev->state != XenbusStateConnected)
1090			xenbus_switch_state(dev, XenbusStateConnected);
1091		break;
1092
1093	case XenbusStateClosed:
1094		if (dev->state == XenbusStateClosed)
1095			break;
1096		/* Missed the backend's Closing state -- fallthrough */
1097	case XenbusStateClosing:
1098		scsifront_disconnect(info);
1099		break;
1100
1101	case XenbusStateReconfiguring:
1102		scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
1103		xenbus_switch_state(dev, XenbusStateReconfiguring);
1104		break;
1105
1106	case XenbusStateReconfigured:
1107		scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1108		xenbus_switch_state(dev, XenbusStateConnected);
1109		break;
1110	}
1111}
1112
1113static const struct xenbus_device_id scsifront_ids[] = {
1114	{ "vscsi" },
1115	{ "" }
1116};
1117
1118static struct xenbus_driver scsifront_driver = {
1119	.ids			= scsifront_ids,
1120	.probe			= scsifront_probe,
1121	.remove			= scsifront_remove,
1122	.resume			= scsifront_resume,
1123	.suspend		= scsifront_suspend,
1124	.otherend_changed	= scsifront_backend_changed,
1125};
1126
1127static int __init scsifront_init(void)
1128{
1129	if (!xen_domain())
1130		return -ENODEV;
1131
1132	return xenbus_register_frontend(&scsifront_driver);
1133}
1134module_init(scsifront_init);
1135
1136static void __exit scsifront_exit(void)
1137{
1138	xenbus_unregister_driver(&scsifront_driver);
1139}
1140module_exit(scsifront_exit);
1141
1142MODULE_DESCRIPTION("Xen SCSI frontend driver");
1143MODULE_LICENSE("GPL");
1144MODULE_ALIAS("xen:vscsi");
1145MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");