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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 = (unsigned long)seg & ~PAGE_MASK;
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 memset(shadow, 0, sizeof(*shadow));
538
539 shadow->sc = sc;
540 shadow->act = VSCSIIF_ACT_SCSI_CDB;
541
542 spin_lock_irqsave(shost->host_lock, flags);
543 if (scsifront_enter(info)) {
544 spin_unlock_irqrestore(shost->host_lock, flags);
545 return SCSI_MLQUEUE_HOST_BUSY;
546 }
547
548 err = map_data_for_request(info, sc, shadow);
549 if (err < 0) {
550 pr_debug("%s: err %d\n", __func__, err);
551 scsifront_return(info);
552 spin_unlock_irqrestore(shost->host_lock, flags);
553 if (err == -ENOMEM)
554 return SCSI_MLQUEUE_HOST_BUSY;
555 sc->result = DID_ERROR << 16;
556 sc->scsi_done(sc);
557 return 0;
558 }
559
560 if (scsifront_do_request(info, shadow)) {
561 scsifront_gnttab_done(info, shadow);
562 goto busy;
563 }
564
565 scsifront_return(info);
566 spin_unlock_irqrestore(shost->host_lock, flags);
567
568 return 0;
569
570busy:
571 scsifront_return(info);
572 spin_unlock_irqrestore(shost->host_lock, flags);
573 pr_debug("%s: busy\n", __func__);
574 return SCSI_MLQUEUE_HOST_BUSY;
575}
576
577/*
578 * Any exception handling (reset or abort) must be forwarded to the backend.
579 * We have to wait until an answer is returned. This answer contains the
580 * result to be returned to the requestor.
581 */
582static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)
583{
584 struct Scsi_Host *host = sc->device->host;
585 struct vscsifrnt_info *info = shost_priv(host);
586 struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
587 int err = 0;
588
589 shadow = kzalloc(sizeof(*shadow), GFP_NOIO);
590 if (!shadow)
591 return FAILED;
592
593 shadow->act = act;
594 shadow->rslt_reset = RSLT_RESET_WAITING;
595 shadow->sc = sc;
596 shadow->ref_rqid = s->rqid;
597 init_waitqueue_head(&shadow->wq_reset);
598
599 spin_lock_irq(host->host_lock);
600
601 for (;;) {
602 if (scsifront_enter(info))
603 goto fail;
604
605 if (!scsifront_do_request(info, shadow))
606 break;
607
608 scsifront_return(info);
609 if (err)
610 goto fail;
611 info->wait_ring_available = 1;
612 spin_unlock_irq(host->host_lock);
613 err = wait_event_interruptible(info->wq_sync,
614 !info->wait_ring_available);
615 spin_lock_irq(host->host_lock);
616 }
617
618 spin_unlock_irq(host->host_lock);
619 err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
620 spin_lock_irq(host->host_lock);
621
622 if (!err) {
623 err = shadow->rslt_reset;
624 scsifront_put_rqid(info, shadow->rqid);
625 kfree(shadow);
626 } else {
627 spin_lock(&info->shadow_lock);
628 shadow->rslt_reset = RSLT_RESET_ERR;
629 spin_unlock(&info->shadow_lock);
630 err = FAILED;
631 }
632
633 scsifront_return(info);
634 spin_unlock_irq(host->host_lock);
635 return err;
636
637fail:
638 spin_unlock_irq(host->host_lock);
639 kfree(shadow);
640 return FAILED;
641}
642
643static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
644{
645 pr_debug("%s\n", __func__);
646 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);
647}
648
649static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
650{
651 pr_debug("%s\n", __func__);
652 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);
653}
654
655static int scsifront_sdev_configure(struct scsi_device *sdev)
656{
657 struct vscsifrnt_info *info = shost_priv(sdev->host);
658
659 if (info && current == info->curr)
660 xenbus_printf(XBT_NIL, info->dev->nodename,
661 info->dev_state_path, "%d", XenbusStateConnected);
662
663 return 0;
664}
665
666static void scsifront_sdev_destroy(struct scsi_device *sdev)
667{
668 struct vscsifrnt_info *info = shost_priv(sdev->host);
669
670 if (info && current == info->curr)
671 xenbus_printf(XBT_NIL, info->dev->nodename,
672 info->dev_state_path, "%d", XenbusStateClosed);
673}
674
675static struct scsi_host_template scsifront_sht = {
676 .module = THIS_MODULE,
677 .name = "Xen SCSI frontend driver",
678 .queuecommand = scsifront_queuecommand,
679 .eh_abort_handler = scsifront_eh_abort_handler,
680 .eh_device_reset_handler = scsifront_dev_reset_handler,
681 .slave_configure = scsifront_sdev_configure,
682 .slave_destroy = scsifront_sdev_destroy,
683 .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN,
684 .can_queue = VSCSIIF_MAX_REQS,
685 .this_id = -1,
686 .cmd_size = sizeof(struct vscsifrnt_shadow),
687 .sg_tablesize = VSCSIIF_SG_TABLESIZE,
688 .use_clustering = DISABLE_CLUSTERING,
689 .proc_name = "scsifront",
690};
691
692static int scsifront_alloc_ring(struct vscsifrnt_info *info)
693{
694 struct xenbus_device *dev = info->dev;
695 struct vscsiif_sring *sring;
696 grant_ref_t gref;
697 int err = -ENOMEM;
698
699 /***** Frontend to Backend ring start *****/
700 sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL);
701 if (!sring) {
702 xenbus_dev_fatal(dev, err,
703 "fail to allocate shared ring (Front to Back)");
704 return err;
705 }
706 SHARED_RING_INIT(sring);
707 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
708
709 err = xenbus_grant_ring(dev, sring, 1, &gref);
710 if (err < 0) {
711 free_page((unsigned long)sring);
712 xenbus_dev_fatal(dev, err,
713 "fail to grant shared ring (Front to Back)");
714 return err;
715 }
716 info->ring_ref = gref;
717
718 err = xenbus_alloc_evtchn(dev, &info->evtchn);
719 if (err) {
720 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
721 goto free_gnttab;
722 }
723
724 err = bind_evtchn_to_irq(info->evtchn);
725 if (err <= 0) {
726 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
727 goto free_gnttab;
728 }
729
730 info->irq = err;
731
732 err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
733 IRQF_ONESHOT, "scsifront", info);
734 if (err) {
735 xenbus_dev_fatal(dev, err, "request_threaded_irq");
736 goto free_irq;
737 }
738
739 return 0;
740
741/* free resource */
742free_irq:
743 unbind_from_irqhandler(info->irq, info);
744free_gnttab:
745 gnttab_end_foreign_access(info->ring_ref, 0,
746 (unsigned long)info->ring.sring);
747
748 return err;
749}
750
751static void scsifront_free_ring(struct vscsifrnt_info *info)
752{
753 unbind_from_irqhandler(info->irq, info);
754 gnttab_end_foreign_access(info->ring_ref, 0,
755 (unsigned long)info->ring.sring);
756}
757
758static int scsifront_init_ring(struct vscsifrnt_info *info)
759{
760 struct xenbus_device *dev = info->dev;
761 struct xenbus_transaction xbt;
762 int err;
763
764 pr_debug("%s\n", __func__);
765
766 err = scsifront_alloc_ring(info);
767 if (err)
768 return err;
769 pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
770
771again:
772 err = xenbus_transaction_start(&xbt);
773 if (err)
774 xenbus_dev_fatal(dev, err, "starting transaction");
775
776 err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
777 info->ring_ref);
778 if (err) {
779 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
780 goto fail;
781 }
782
783 err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
784 info->evtchn);
785
786 if (err) {
787 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
788 goto fail;
789 }
790
791 err = xenbus_transaction_end(xbt, 0);
792 if (err) {
793 if (err == -EAGAIN)
794 goto again;
795 xenbus_dev_fatal(dev, err, "completing transaction");
796 goto free_sring;
797 }
798
799 return 0;
800
801fail:
802 xenbus_transaction_end(xbt, 1);
803free_sring:
804 scsifront_free_ring(info);
805
806 return err;
807}
808
809
810static int scsifront_probe(struct xenbus_device *dev,
811 const struct xenbus_device_id *id)
812{
813 struct vscsifrnt_info *info;
814 struct Scsi_Host *host;
815 int err = -ENOMEM;
816 char name[TASK_COMM_LEN];
817
818 host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
819 if (!host) {
820 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
821 return err;
822 }
823 info = (struct vscsifrnt_info *)host->hostdata;
824
825 dev_set_drvdata(&dev->dev, info);
826 info->dev = dev;
827
828 bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
829
830 err = scsifront_init_ring(info);
831 if (err) {
832 scsi_host_put(host);
833 return err;
834 }
835
836 init_waitqueue_head(&info->wq_sync);
837 init_waitqueue_head(&info->wq_pause);
838 spin_lock_init(&info->shadow_lock);
839
840 snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
841
842 host->max_id = VSCSIIF_MAX_TARGET;
843 host->max_channel = 0;
844 host->max_lun = VSCSIIF_MAX_LUN;
845 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
846 host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
847
848 err = scsi_add_host(host, &dev->dev);
849 if (err) {
850 dev_err(&dev->dev, "fail to add scsi host %d\n", err);
851 goto free_sring;
852 }
853 info->host = host;
854 info->host_active = 1;
855
856 xenbus_switch_state(dev, XenbusStateInitialised);
857
858 return 0;
859
860free_sring:
861 scsifront_free_ring(info);
862 scsi_host_put(host);
863 return err;
864}
865
866static int scsifront_resume(struct xenbus_device *dev)
867{
868 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
869 struct Scsi_Host *host = info->host;
870 int err;
871
872 spin_lock_irq(host->host_lock);
873
874 /* Finish all still pending commands. */
875 scsifront_finish_all(info);
876
877 spin_unlock_irq(host->host_lock);
878
879 /* Reconnect to dom0. */
880 scsifront_free_ring(info);
881 err = scsifront_init_ring(info);
882 if (err) {
883 dev_err(&dev->dev, "fail to resume %d\n", err);
884 scsi_host_put(host);
885 return err;
886 }
887
888 xenbus_switch_state(dev, XenbusStateInitialised);
889
890 return 0;
891}
892
893static int scsifront_suspend(struct xenbus_device *dev)
894{
895 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
896 struct Scsi_Host *host = info->host;
897 int err = 0;
898
899 /* No new commands for the backend. */
900 spin_lock_irq(host->host_lock);
901 info->pause = 1;
902 while (info->callers && !err) {
903 info->waiting_pause = 1;
904 info->wait_ring_available = 0;
905 spin_unlock_irq(host->host_lock);
906 wake_up(&info->wq_sync);
907 err = wait_event_interruptible(info->wq_pause,
908 !info->waiting_pause);
909 spin_lock_irq(host->host_lock);
910 }
911 spin_unlock_irq(host->host_lock);
912 return err;
913}
914
915static int scsifront_remove(struct xenbus_device *dev)
916{
917 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
918
919 pr_debug("%s: %s removed\n", __func__, dev->nodename);
920
921 mutex_lock(&scsifront_mutex);
922 if (info->host_active) {
923 /* Scsi_host not yet removed */
924 scsi_remove_host(info->host);
925 info->host_active = 0;
926 }
927 mutex_unlock(&scsifront_mutex);
928
929 scsifront_free_ring(info);
930 scsi_host_put(info->host);
931
932 return 0;
933}
934
935static void scsifront_disconnect(struct vscsifrnt_info *info)
936{
937 struct xenbus_device *dev = info->dev;
938 struct Scsi_Host *host = info->host;
939
940 pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
941
942 /*
943 * When this function is executed, all devices of
944 * Frontend have been deleted.
945 * Therefore, it need not block I/O before remove_host.
946 */
947
948 mutex_lock(&scsifront_mutex);
949 if (info->host_active) {
950 scsi_remove_host(host);
951 info->host_active = 0;
952 }
953 mutex_unlock(&scsifront_mutex);
954
955 xenbus_frontend_closed(dev);
956}
957
958static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
959{
960 struct xenbus_device *dev = info->dev;
961 int i, err = 0;
962 char str[64];
963 char **dir;
964 unsigned int dir_n = 0;
965 unsigned int device_state;
966 unsigned int hst, chn, tgt, lun;
967 struct scsi_device *sdev;
968
969 dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
970 if (IS_ERR(dir))
971 return;
972
973 /* mark current task as the one allowed to modify device states */
974 BUG_ON(info->curr);
975 info->curr = current;
976
977 for (i = 0; i < dir_n; i++) {
978 /* read status */
979 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
980 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
981 &device_state);
982 if (XENBUS_EXIST_ERR(err))
983 continue;
984
985 /* virtual SCSI device */
986 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
987 err = xenbus_scanf(XBT_NIL, dev->otherend, str,
988 "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
989 if (XENBUS_EXIST_ERR(err))
990 continue;
991
992 /*
993 * Front device state path, used in slave_configure called
994 * on successfull scsi_add_device, and in slave_destroy called
995 * on remove of a device.
996 */
997 snprintf(info->dev_state_path, sizeof(info->dev_state_path),
998 "vscsi-devs/%s/state", dir[i]);
999
1000 switch (op) {
1001 case VSCSIFRONT_OP_ADD_LUN:
1002 if (device_state != XenbusStateInitialised)
1003 break;
1004
1005 if (scsi_add_device(info->host, chn, tgt, lun)) {
1006 dev_err(&dev->dev, "scsi_add_device\n");
1007 xenbus_printf(XBT_NIL, dev->nodename,
1008 info->dev_state_path,
1009 "%d", XenbusStateClosed);
1010 }
1011 break;
1012 case VSCSIFRONT_OP_DEL_LUN:
1013 if (device_state != XenbusStateClosing)
1014 break;
1015
1016 sdev = scsi_device_lookup(info->host, chn, tgt, lun);
1017 if (sdev) {
1018 scsi_remove_device(sdev);
1019 scsi_device_put(sdev);
1020 }
1021 break;
1022 case VSCSIFRONT_OP_READD_LUN:
1023 if (device_state == XenbusStateConnected)
1024 xenbus_printf(XBT_NIL, dev->nodename,
1025 info->dev_state_path,
1026 "%d", XenbusStateConnected);
1027 break;
1028 default:
1029 break;
1030 }
1031 }
1032
1033 info->curr = NULL;
1034
1035 kfree(dir);
1036}
1037
1038static void scsifront_read_backend_params(struct xenbus_device *dev,
1039 struct vscsifrnt_info *info)
1040{
1041 unsigned int sg_grant, nr_segs;
1042 struct Scsi_Host *host = info->host;
1043
1044 sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0);
1045 nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
1046 nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
1047 nr_segs = min_t(unsigned int, nr_segs,
1048 VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
1049 sizeof(struct scsiif_request_segment));
1050
1051 if (!info->pause && sg_grant)
1052 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);
1053 else if (info->pause && nr_segs < host->sg_tablesize)
1054 dev_warn(&dev->dev,
1055 "SG entries decreased from %d to %u - device may not work properly anymore\n",
1056 host->sg_tablesize, nr_segs);
1057
1058 host->sg_tablesize = nr_segs;
1059 host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;
1060}
1061
1062static void scsifront_backend_changed(struct xenbus_device *dev,
1063 enum xenbus_state backend_state)
1064{
1065 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1066
1067 pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
1068
1069 switch (backend_state) {
1070 case XenbusStateUnknown:
1071 case XenbusStateInitialising:
1072 case XenbusStateInitWait:
1073 case XenbusStateInitialised:
1074 break;
1075
1076 case XenbusStateConnected:
1077 scsifront_read_backend_params(dev, info);
1078
1079 if (info->pause) {
1080 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);
1081 xenbus_switch_state(dev, XenbusStateConnected);
1082 info->pause = 0;
1083 return;
1084 }
1085
1086 if (xenbus_read_driver_state(dev->nodename) ==
1087 XenbusStateInitialised)
1088 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1089
1090 if (dev->state != XenbusStateConnected)
1091 xenbus_switch_state(dev, XenbusStateConnected);
1092 break;
1093
1094 case XenbusStateClosed:
1095 if (dev->state == XenbusStateClosed)
1096 break;
1097 /* Missed the backend's Closing state -- fallthrough */
1098 case XenbusStateClosing:
1099 scsifront_disconnect(info);
1100 break;
1101
1102 case XenbusStateReconfiguring:
1103 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
1104 xenbus_switch_state(dev, XenbusStateReconfiguring);
1105 break;
1106
1107 case XenbusStateReconfigured:
1108 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1109 xenbus_switch_state(dev, XenbusStateConnected);
1110 break;
1111 }
1112}
1113
1114static const struct xenbus_device_id scsifront_ids[] = {
1115 { "vscsi" },
1116 { "" }
1117};
1118
1119static struct xenbus_driver scsifront_driver = {
1120 .ids = scsifront_ids,
1121 .probe = scsifront_probe,
1122 .remove = scsifront_remove,
1123 .resume = scsifront_resume,
1124 .suspend = scsifront_suspend,
1125 .otherend_changed = scsifront_backend_changed,
1126};
1127
1128static int __init scsifront_init(void)
1129{
1130 if (!xen_domain())
1131 return -ENODEV;
1132
1133 return xenbus_register_frontend(&scsifront_driver);
1134}
1135module_init(scsifront_init);
1136
1137static void __exit scsifront_exit(void)
1138{
1139 xenbus_unregister_driver(&scsifront_driver);
1140}
1141module_exit(scsifront_exit);
1142
1143MODULE_DESCRIPTION("Xen SCSI frontend driver");
1144MODULE_LICENSE("GPL");
1145MODULE_ALIAS("xen:vscsi");
1146MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");