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	unsigned long mfn;
381	struct scsiif_request_segment *seg;
382
383	ring_req->nr_segments = 0;
384	if (sc->sc_data_direction == DMA_NONE || !data_len)
385		return 0;
386
387	scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)
388		data_grants += PFN_UP(sg->offset + sg->length);
389
390	if (data_grants > VSCSIIF_SG_TABLESIZE) {
391		if (data_grants > info->host->sg_tablesize) {
392			shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
393			     "Unable to map request_buffer for command!\n");
394			return -E2BIG;
395		}
396		seg_grants = vscsiif_grants_sg(data_grants);
397		shadow->sg = kcalloc(data_grants,
398			sizeof(struct scsiif_request_segment), GFP_ATOMIC);
399		if (!shadow->sg)
400			return -ENOMEM;
401	}
402	seg = shadow->sg ? : ring_req->seg;
403
404	err = gnttab_alloc_grant_references(seg_grants + data_grants,
405					    &gref_head);
406	if (err) {
407		kfree(shadow->sg);
408		shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
409			     "gnttab_alloc_grant_references() error\n");
410		return -ENOMEM;
411	}
412
413	if (seg_grants) {
414		page = virt_to_page(seg);
415		off = (unsigned long)seg & ~PAGE_MASK;
416		len = sizeof(struct scsiif_request_segment) * data_grants;
417		while (len > 0) {
418			bytes = min_t(unsigned int, len, PAGE_SIZE - off);
419
420			ref = gnttab_claim_grant_reference(&gref_head);
421			BUG_ON(ref == -ENOSPC);
422
423			mfn = pfn_to_mfn(page_to_pfn(page));
424			gnttab_grant_foreign_access_ref(ref,
425				info->dev->otherend_id, mfn, 1);
426			shadow->gref[ref_cnt] = ref;
427			ring_req->seg[ref_cnt].gref   = ref;
428			ring_req->seg[ref_cnt].offset = (uint16_t)off;
429			ring_req->seg[ref_cnt].length = (uint16_t)bytes;
430
431			page++;
432			len -= bytes;
433			off = 0;
434			ref_cnt++;
435		}
436		BUG_ON(seg_grants < ref_cnt);
437		seg_grants = ref_cnt;
438	}
439
440	scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {
441		page = sg_page(sg);
442		off = sg->offset;
443		len = sg->length;
444
445		while (len > 0 && data_len > 0) {
446			/*
447			 * sg sends a scatterlist that is larger than
448			 * the data_len it wants transferred for certain
449			 * IO sizes.
450			 */
451			bytes = min_t(unsigned int, len, PAGE_SIZE - off);
452			bytes = min(bytes, data_len);
453
454			ref = gnttab_claim_grant_reference(&gref_head);
455			BUG_ON(ref == -ENOSPC);
456
457			mfn = pfn_to_mfn(page_to_pfn(page));
458			gnttab_grant_foreign_access_ref(ref,
459				info->dev->otherend_id, mfn, 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