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MAINTAINERS: Add xen pvscsi maintainer
[mirror_ubuntu-artful-kernel.git] / drivers / scsi / xen-scsifront.c
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8beb8d4c
JG		 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
67/* Tuning point. */
68#define VSCSIIF_DEFAULT_CMD_PER_LUN 10
69#define VSCSIIF_MAX_TARGET 64
70#define VSCSIIF_MAX_LUN 255
71
72#define VSCSIIF_RING_SIZE __CONST_RING_SIZE(vscsiif, PAGE_SIZE)
73#define VSCSIIF_MAX_REQS VSCSIIF_RING_SIZE
74
75#define vscsiif_grants_sg(_sg) (PFN_UP((_sg) * \
76 sizeof(struct scsiif_request_segment)))
77
78struct vscsifrnt_shadow {
79 /* command between backend and frontend */
80 unsigned char act;
81 uint16_t rqid;
82
83 unsigned int nr_grants; /* number of grants in gref[] */
84 struct scsiif_request_segment *sg; /* scatter/gather elements */
85
86 /* Do reset or abort function. */
87 wait_queue_head_t wq_reset; /* reset work queue */
88 int wait_reset; /* reset work queue condition */
89 int32_t rslt_reset; /* reset response status: */
90 /* SUCCESS or FAILED or: */
91#define RSLT_RESET_WAITING 0
92#define RSLT_RESET_ERR -1
93
94 /* Requested struct scsi_cmnd is stored from kernel. */
95 struct scsi_cmnd *sc;
96 int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL];
97};
98
99struct vscsifrnt_info {
100 struct xenbus_device *dev;
101
102 struct Scsi_Host *host;
103 int host_active;
104
105 unsigned int evtchn;
106 unsigned int irq;
107
108 grant_ref_t ring_ref;
109 struct vscsiif_front_ring ring;
110 struct vscsiif_response ring_rsp;
111
112 spinlock_t shadow_lock;
113 DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS);
114 struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS];
115
116 wait_queue_head_t wq_sync;
117 unsigned int wait_ring_available:1;
118
119 char dev_state_path[64];
120 struct task_struct *curr;
121};
122
123static DEFINE_MUTEX(scsifront_mutex);
124
125static void scsifront_wake_up(struct vscsifrnt_info *info)
126{
127 info->wait_ring_available = 0;
128 wake_up(&info->wq_sync);
129}
130
131static int scsifront_get_rqid(struct vscsifrnt_info *info)
132{
133 unsigned long flags;
134 int free;
135
136 spin_lock_irqsave(&info->shadow_lock, flags);
137
138 free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
139 __clear_bit(free, info->shadow_free_bitmap);
140
141 spin_unlock_irqrestore(&info->shadow_lock, flags);
142
143 return free;
144}
145
146static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
147{
148 int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
149
150 __set_bit(id, info->shadow_free_bitmap);
151 info->shadow[id] = NULL;
152
153 return empty || info->wait_ring_available;
154}
155
156static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
157{
158 unsigned long flags;
159 int kick;
160
161 spin_lock_irqsave(&info->shadow_lock, flags);
162 kick = _scsifront_put_rqid(info, id);
163 spin_unlock_irqrestore(&info->shadow_lock, flags);
164
165 if (kick)
166 scsifront_wake_up(info);
167}
168
169static struct vscsiif_request *scsifront_pre_req(struct vscsifrnt_info *info)
170{
171 struct vscsiif_front_ring *ring = &(info->ring);
172 struct vscsiif_request *ring_req;
173 uint32_t id;
174
175 id = scsifront_get_rqid(info); /* use id in response */
176 if (id >= VSCSIIF_MAX_REQS)
177 return NULL;
178
179 ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt);
180
181 ring->req_prod_pvt++;
182
183 ring_req->rqid = (uint16_t)id;
184
185 return ring_req;
186}
187
188static void scsifront_do_request(struct vscsifrnt_info *info)
189{
190 struct vscsiif_front_ring *ring = &(info->ring);
191 int notify;
192
193 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify);
194 if (notify)
195 notify_remote_via_irq(info->irq);
196}
197
198static void scsifront_gnttab_done(struct vscsifrnt_info *info, uint32_t id)
199{
200 struct vscsifrnt_shadow *s = info->shadow[id];
201 int i;
202
203 if (s->sc->sc_data_direction == DMA_NONE)
204 return;
205
206 for (i = 0; i < s->nr_grants; i++) {
207 if (unlikely(gnttab_query_foreign_access(s->gref[i]) != 0)) {
208 shost_printk(KERN_ALERT, info->host, KBUILD_MODNAME
209 "grant still in use by backend\n");
210 BUG();
211 }
212 gnttab_end_foreign_access(s->gref[i], 0, 0UL);
213 }
214
215 kfree(s->sg);
216}
217
218static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info,
219 struct vscsiif_response *ring_rsp)
220{
221 struct scsi_cmnd *sc;
222 uint32_t id;
223 uint8_t sense_len;
224
225 id = ring_rsp->rqid;
226 sc = info->shadow[id]->sc;
227
228 BUG_ON(sc == NULL);
229
230 scsifront_gnttab_done(info, id);
231 scsifront_put_rqid(info, id);
232
233 sc->result = ring_rsp->rslt;
234 scsi_set_resid(sc, ring_rsp->residual_len);
235
236 sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE,
237 ring_rsp->sense_len);
238
239 if (sense_len)
240 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len);
241
242 sc->scsi_done(sc);
243}
244
245static void scsifront_sync_cmd_done(struct vscsifrnt_info *info,
246 struct vscsiif_response *ring_rsp)
247{
248 uint16_t id = ring_rsp->rqid;
249 unsigned long flags;
250 struct vscsifrnt_shadow *shadow = info->shadow[id];
251 int kick;
252
253 spin_lock_irqsave(&info->shadow_lock, flags);
254 shadow->wait_reset = 1;
255 switch (shadow->rslt_reset) {
256 case RSLT_RESET_WAITING:
257 shadow->rslt_reset = ring_rsp->rslt;
258 break;
259 case RSLT_RESET_ERR:
260 kick = _scsifront_put_rqid(info, id);
261 spin_unlock_irqrestore(&info->shadow_lock, flags);
262 kfree(shadow);
263 if (kick)
264 scsifront_wake_up(info);
265 return;
266 default:
267 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
268 "bad reset state %d, possibly leaking %u\n",
269 shadow->rslt_reset, id);
270 break;
271 }
272 spin_unlock_irqrestore(&info->shadow_lock, flags);
273
274 wake_up(&shadow->wq_reset);
275}
276
277static int scsifront_cmd_done(struct vscsifrnt_info *info)
278{
279 struct vscsiif_response *ring_rsp;
280 RING_IDX i, rp;
281 int more_to_do = 0;
282 unsigned long flags;
283
284 spin_lock_irqsave(info->host->host_lock, flags);
285
286 rp = info->ring.sring->rsp_prod;
287 rmb(); /* ordering required respective to dom0 */
288 for (i = info->ring.rsp_cons; i != rp; i++) {
289
290 ring_rsp = RING_GET_RESPONSE(&info->ring, i);
291
292 if (WARN(ring_rsp->rqid >= VSCSIIF_MAX_REQS ||
293 test_bit(ring_rsp->rqid, info->shadow_free_bitmap),
294 "illegal rqid %u returned by backend!\n",
295 ring_rsp->rqid))
296 continue;
297
298 if (info->shadow[ring_rsp->rqid]->act == VSCSIIF_ACT_SCSI_CDB)
299 scsifront_cdb_cmd_done(info, ring_rsp);
300 else
301 scsifront_sync_cmd_done(info, ring_rsp);
302 }
303
304 info->ring.rsp_cons = i;
305
306 if (i != info->ring.req_prod_pvt)
307 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
308 else
309 info->ring.sring->rsp_event = i + 1;
310
311 info->wait_ring_available = 0;
312
313 spin_unlock_irqrestore(info->host->host_lock, flags);
314
315 wake_up(&info->wq_sync);
316
317 return more_to_do;
318}
319
320static irqreturn_t scsifront_irq_fn(int irq, void *dev_id)
321{
322 struct vscsifrnt_info *info = dev_id;
323
324 while (scsifront_cmd_done(info))
325 /* Yield point for this unbounded loop. */
326 cond_resched();
327
328 return IRQ_HANDLED;
329}
330
331static int map_data_for_request(struct vscsifrnt_info *info,
332 struct scsi_cmnd *sc,
333 struct vscsiif_request *ring_req,
334 struct vscsifrnt_shadow *shadow)
335{
336 grant_ref_t gref_head;
337 struct page *page;
338 int err, ref, ref_cnt = 0;
339 int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE);
340 unsigned int i, off, len, bytes;
341 unsigned int data_len = scsi_bufflen(sc);
342 unsigned int data_grants = 0, seg_grants = 0;
343 struct scatterlist *sg;
344 unsigned long mfn;
345 struct scsiif_request_segment *seg;
346
347 ring_req->nr_segments = 0;
348 if (sc->sc_data_direction == DMA_NONE || !data_len)
349 return 0;
350
351 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)
352 data_grants += PFN_UP(sg->offset + sg->length);
353
354 if (data_grants > VSCSIIF_SG_TABLESIZE) {
355 if (data_grants > info->host->sg_tablesize) {
356 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
357 "Unable to map request_buffer for command!\n");
358 return -E2BIG;
359 }
360 seg_grants = vscsiif_grants_sg(data_grants);
361 shadow->sg = kcalloc(data_grants,
362 sizeof(struct scsiif_request_segment), GFP_NOIO);
363 if (!shadow->sg)
364 return -ENOMEM;
365 }
366 seg = shadow->sg ? : ring_req->seg;
367
368 err = gnttab_alloc_grant_references(seg_grants + data_grants,
369 &gref_head);
370 if (err) {
371 kfree(shadow->sg);
372 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
373 "gnttab_alloc_grant_references() error\n");
374 return -ENOMEM;
375 }
376
377 if (seg_grants) {
378 page = virt_to_page(seg);
379 off = (unsigned long)seg & ~PAGE_MASK;
380 len = sizeof(struct scsiif_request_segment) * data_grants;
381 while (len > 0) {
382 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
383
384 ref = gnttab_claim_grant_reference(&gref_head);
385 BUG_ON(ref == -ENOSPC);
386
387 mfn = pfn_to_mfn(page_to_pfn(page));
388 gnttab_grant_foreign_access_ref(ref,
389 info->dev->otherend_id, mfn, 1);
390 shadow->gref[ref_cnt] = ref;
391 ring_req->seg[ref_cnt].gref = ref;
392 ring_req->seg[ref_cnt].offset = (uint16_t)off;
393 ring_req->seg[ref_cnt].length = (uint16_t)bytes;
394
395 page++;
396 len -= bytes;
397 off = 0;
398 ref_cnt++;
399 }
400 BUG_ON(seg_grants < ref_cnt);
401 seg_grants = ref_cnt;
402 }
403
404 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {
405 page = sg_page(sg);
406 off = sg->offset;
407 len = sg->length;
408
409 while (len > 0 && data_len > 0) {
410 /*
411 * sg sends a scatterlist that is larger than
412 * the data_len it wants transferred for certain
413 * IO sizes.
414 */
415 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
416 bytes = min(bytes, data_len);
417
418 ref = gnttab_claim_grant_reference(&gref_head);
419 BUG_ON(ref == -ENOSPC);
420
421 mfn = pfn_to_mfn(page_to_pfn(page));
422 gnttab_grant_foreign_access_ref(ref,
423 info->dev->otherend_id, mfn, grant_ro);
424
425 shadow->gref[ref_cnt] = ref;
426 seg->gref = ref;
427 seg->offset = (uint16_t)off;
428 seg->length = (uint16_t)bytes;
429
430 page++;
431 seg++;
432 len -= bytes;
433 data_len -= bytes;
434 off = 0;
435 ref_cnt++;
436 }
437 }
438
439 if (seg_grants)
440 ring_req->nr_segments = VSCSIIF_SG_GRANT | seg_grants;
441 else
442 ring_req->nr_segments = (uint8_t)ref_cnt;
443 shadow->nr_grants = ref_cnt;
444
445 return 0;
446}
447
448static struct vscsiif_request *scsifront_command2ring(
449 struct vscsifrnt_info *info, struct scsi_cmnd *sc,
450 struct vscsifrnt_shadow *shadow)
451{
452 struct vscsiif_request *ring_req;
453
454 memset(shadow, 0, sizeof(*shadow));
455
456 ring_req = scsifront_pre_req(info);
457 if (!ring_req)
458 return NULL;
459
460 info->shadow[ring_req->rqid] = shadow;
461 shadow->rqid = ring_req->rqid;
462
463 ring_req->id = sc->device->id;
464 ring_req->lun = sc->device->lun;
465 ring_req->channel = sc->device->channel;
466 ring_req->cmd_len = sc->cmd_len;
467
468 BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE);
469
470 memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len);
471
472 ring_req->sc_data_direction = (uint8_t)sc->sc_data_direction;
473 ring_req->timeout_per_command = sc->request->timeout / HZ;
474
475 return ring_req;
476}
477
478static int scsifront_queuecommand(struct Scsi_Host *shost,
479 struct scsi_cmnd *sc)
480{
481 struct vscsifrnt_info *info = shost_priv(shost);
482 struct vscsiif_request *ring_req;
483 struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc);
484 unsigned long flags;
485 int err;
486 uint16_t rqid;
487
488 spin_lock_irqsave(shost->host_lock, flags);
489 if (RING_FULL(&info->ring))
490 goto busy;
491
492 ring_req = scsifront_command2ring(info, sc, shadow);
493 if (!ring_req)
494 goto busy;
495
496 sc->result = 0;
497
498 rqid = ring_req->rqid;
499 ring_req->act = VSCSIIF_ACT_SCSI_CDB;
500
501 shadow->sc = sc;
502 shadow->act = VSCSIIF_ACT_SCSI_CDB;
503
504 err = map_data_for_request(info, sc, ring_req, shadow);
505 if (err < 0) {
506 pr_debug("%s: err %d\n", __func__, err);
507 scsifront_put_rqid(info, rqid);
508 spin_unlock_irqrestore(shost->host_lock, flags);
509 if (err == -ENOMEM)
510 return SCSI_MLQUEUE_HOST_BUSY;
511 sc->result = DID_ERROR << 16;
512 sc->scsi_done(sc);
513 return 0;
514 }
515
516 scsifront_do_request(info);
517 spin_unlock_irqrestore(shost->host_lock, flags);
518
519 return 0;
520
521busy:
522 spin_unlock_irqrestore(shost->host_lock, flags);
523 pr_debug("%s: busy\n", __func__);
524 return SCSI_MLQUEUE_HOST_BUSY;
525}
526
527/*
528 * Any exception handling (reset or abort) must be forwarded to the backend.
529 * We have to wait until an answer is returned. This answer contains the
530 * result to be returned to the requestor.
531 */
532static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)
533{
534 struct Scsi_Host *host = sc->device->host;
535 struct vscsifrnt_info *info = shost_priv(host);
536 struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
537 struct vscsiif_request *ring_req;
538 int err = 0;
539
540 shadow = kmalloc(sizeof(*shadow), GFP_NOIO);
541 if (!shadow)
542 return FAILED;
543
544 for (;;) {
545 spin_lock_irq(host->host_lock);
546 if (!RING_FULL(&info->ring)) {
547 ring_req = scsifront_command2ring(info, sc, shadow);
548 if (ring_req)
549 break;
550 }
551 if (err) {
552 spin_unlock_irq(host->host_lock);
553 kfree(shadow);
554 return FAILED;
555 }
556 info->wait_ring_available = 1;
557 spin_unlock_irq(host->host_lock);
558 err = wait_event_interruptible(info->wq_sync,
559 !info->wait_ring_available);
560 spin_lock_irq(host->host_lock);
561 }
562
563 ring_req->act = act;
564 ring_req->ref_rqid = s->rqid;
565
566 shadow->act = act;
567 shadow->rslt_reset = RSLT_RESET_WAITING;
568 init_waitqueue_head(&shadow->wq_reset);
569
570 ring_req->nr_segments = 0;
571
572 scsifront_do_request(info);
573
574 spin_unlock_irq(host->host_lock);
575 err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
576 spin_lock_irq(host->host_lock);
577
578 if (!err) {
579 err = shadow->rslt_reset;
580 scsifront_put_rqid(info, shadow->rqid);
581 kfree(shadow);
582 } else {
583 spin_lock(&info->shadow_lock);
584 shadow->rslt_reset = RSLT_RESET_ERR;
585 spin_unlock(&info->shadow_lock);
586 err = FAILED;
587 }
588
589 spin_unlock_irq(host->host_lock);
590 return err;
591}
592
593static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
594{
595 pr_debug("%s\n", __func__);
596 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);
597}
598
599static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
600{
601 pr_debug("%s\n", __func__);
602 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);
603}
604
605static int scsifront_sdev_configure(struct scsi_device *sdev)
606{
607 struct vscsifrnt_info *info = shost_priv(sdev->host);
608
609 if (info && current == info->curr)
610 xenbus_printf(XBT_NIL, info->dev->nodename,
611 info->dev_state_path, "%d", XenbusStateConnected);
612
613 return 0;
614}
615
616static void scsifront_sdev_destroy(struct scsi_device *sdev)
617{
618 struct vscsifrnt_info *info = shost_priv(sdev->host);
619
620 if (info && current == info->curr)
621 xenbus_printf(XBT_NIL, info->dev->nodename,
622 info->dev_state_path, "%d", XenbusStateClosed);
623}
624
625static struct scsi_host_template scsifront_sht = {
626 .module = THIS_MODULE,
627 .name = "Xen SCSI frontend driver",
628 .queuecommand = scsifront_queuecommand,
629 .eh_abort_handler = scsifront_eh_abort_handler,
630 .eh_device_reset_handler = scsifront_dev_reset_handler,
631 .slave_configure = scsifront_sdev_configure,
632 .slave_destroy = scsifront_sdev_destroy,
633 .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN,
634 .can_queue = VSCSIIF_MAX_REQS,
635 .this_id = -1,
636 .cmd_size = sizeof(struct vscsifrnt_shadow),
637 .sg_tablesize = VSCSIIF_SG_TABLESIZE,
638 .use_clustering = DISABLE_CLUSTERING,
639 .proc_name = "scsifront",
640};
641
642static int scsifront_alloc_ring(struct vscsifrnt_info *info)
643{
644 struct xenbus_device *dev = info->dev;
645 struct vscsiif_sring *sring;
646 int err = -ENOMEM;
647
648 /***** Frontend to Backend ring start *****/
649 sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL);
650 if (!sring) {
651 xenbus_dev_fatal(dev, err,
652 "fail to allocate shared ring (Front to Back)");
653 return err;
654 }
655 SHARED_RING_INIT(sring);
656 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
657
658 err = xenbus_grant_ring(dev, virt_to_mfn(sring));
659 if (err < 0) {
660 free_page((unsigned long)sring);
661 xenbus_dev_fatal(dev, err,
662 "fail to grant shared ring (Front to Back)");
663 return err;
664 }
665 info->ring_ref = err;
666
667 err = xenbus_alloc_evtchn(dev, &info->evtchn);
668 if (err) {
669 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
670 goto free_gnttab;
671 }
672
673 err = bind_evtchn_to_irq(info->evtchn);
674 if (err <= 0) {
675 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
676 goto free_gnttab;
677 }
678
679 info->irq = err;
680
681 err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
682 IRQF_ONESHOT, "scsifront", info);
683 if (err) {
684 xenbus_dev_fatal(dev, err, "request_threaded_irq");
685 goto free_irq;
686 }
687
688 return 0;
689
690/* free resource */
691free_irq:
692 unbind_from_irqhandler(info->irq, info);
693free_gnttab:
694 gnttab_end_foreign_access(info->ring_ref, 0,
695 (unsigned long)info->ring.sring);
696
697 return err;
698}
699
700static int scsifront_init_ring(struct vscsifrnt_info *info)
701{
702 struct xenbus_device *dev = info->dev;
703 struct xenbus_transaction xbt;
704 int err;
705
706 pr_debug("%s\n", __func__);
707
708 err = scsifront_alloc_ring(info);
709 if (err)
710 return err;
711 pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
712
713again:
714 err = xenbus_transaction_start(&xbt);
715 if (err)
716 xenbus_dev_fatal(dev, err, "starting transaction");
717
718 err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
719 info->ring_ref);
720 if (err) {
721 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
722 goto fail;
723 }
724
725 err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
726 info->evtchn);
727
728 if (err) {
729 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
730 goto fail;
731 }
732
733 err = xenbus_transaction_end(xbt, 0);
734 if (err) {
735 if (err == -EAGAIN)
736 goto again;
737 xenbus_dev_fatal(dev, err, "completing transaction");
738 goto free_sring;
739 }
740
741 return 0;
742
743fail:
744 xenbus_transaction_end(xbt, 1);
745free_sring:
746 unbind_from_irqhandler(info->irq, info);
747 gnttab_end_foreign_access(info->ring_ref, 0,
748 (unsigned long)info->ring.sring);
749
750 return err;
751}
752
753
754static int scsifront_probe(struct xenbus_device *dev,
755 const struct xenbus_device_id *id)
756{
757 struct vscsifrnt_info *info;
758 struct Scsi_Host *host;
759 int err = -ENOMEM;
760 char name[TASK_COMM_LEN];
761
762 host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
763 if (!host) {
764 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
765 return err;
766 }
767 info = (struct vscsifrnt_info *)host->hostdata;
768
769 dev_set_drvdata(&dev->dev, info);
770 info->dev = dev;
771
772 bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
773
774 err = scsifront_init_ring(info);
775 if (err) {
776 scsi_host_put(host);
777 return err;
778 }
779
780 init_waitqueue_head(&info->wq_sync);
781 spin_lock_init(&info->shadow_lock);
782
783 snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
784
785 host->max_id = VSCSIIF_MAX_TARGET;
786 host->max_channel = 0;
787 host->max_lun = VSCSIIF_MAX_LUN;
788 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
789 host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
790
791 err = scsi_add_host(host, &dev->dev);
792 if (err) {
793 dev_err(&dev->dev, "fail to add scsi host %d\n", err);
794 goto free_sring;
795 }
796 info->host = host;
797 info->host_active = 1;
798
799 xenbus_switch_state(dev, XenbusStateInitialised);
800
801 return 0;
802
803free_sring:
804 unbind_from_irqhandler(info->irq, info);
805 gnttab_end_foreign_access(info->ring_ref, 0,
806 (unsigned long)info->ring.sring);
807 scsi_host_put(host);
808 return err;
809}
810
811static int scsifront_remove(struct xenbus_device *dev)
812{
813 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
814
815 pr_debug("%s: %s removed\n", __func__, dev->nodename);
816
817 mutex_lock(&scsifront_mutex);
818 if (info->host_active) {
819 /* Scsi_host not yet removed */
820 scsi_remove_host(info->host);
821 info->host_active = 0;
822 }
823 mutex_unlock(&scsifront_mutex);
824
825 gnttab_end_foreign_access(info->ring_ref, 0,
826 (unsigned long)info->ring.sring);
827 unbind_from_irqhandler(info->irq, info);
828
829 scsi_host_put(info->host);
830
831 return 0;
832}
833
834static void scsifront_disconnect(struct vscsifrnt_info *info)
835{
836 struct xenbus_device *dev = info->dev;
837 struct Scsi_Host *host = info->host;
838
839 pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
840
841 /*
842 * When this function is executed, all devices of
843 * Frontend have been deleted.
844 * Therefore, it need not block I/O before remove_host.
845 */
846
847 mutex_lock(&scsifront_mutex);
848 if (info->host_active) {
849 scsi_remove_host(host);
850 info->host_active = 0;
851 }
852 mutex_unlock(&scsifront_mutex);
853
854 xenbus_frontend_closed(dev);
855}
856
857static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
858{
859 struct xenbus_device *dev = info->dev;
860 int i, err = 0;
861 char str[64];
862 char **dir;
863 unsigned int dir_n = 0;
864 unsigned int device_state;
865 unsigned int hst, chn, tgt, lun;
866 struct scsi_device *sdev;
867
868 dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
869 if (IS_ERR(dir))
870 return;
871
872 /* mark current task as the one allowed to modify device states */
873 BUG_ON(info->curr);
874 info->curr = current;
875
876 for (i = 0; i < dir_n; i++) {
877 /* read status */
878 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
879 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
880 &device_state);
881 if (XENBUS_EXIST_ERR(err))
882 continue;
883
884 /* virtual SCSI device */
885 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
886 err = xenbus_scanf(XBT_NIL, dev->otherend, str,
887 "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
888 if (XENBUS_EXIST_ERR(err))
889 continue;
890
891 /*
892 * Front device state path, used in slave_configure called
893 * on successfull scsi_add_device, and in slave_destroy called
894 * on remove of a device.
895 */
896 snprintf(info->dev_state_path, sizeof(info->dev_state_path),
897 "vscsi-devs/%s/state", dir[i]);
898
899 switch (op) {
900 case VSCSIFRONT_OP_ADD_LUN:
901 if (device_state != XenbusStateInitialised)
902 break;
903
904 if (scsi_add_device(info->host, chn, tgt, lun)) {
905 dev_err(&dev->dev, "scsi_add_device\n");
906 xenbus_printf(XBT_NIL, dev->nodename,
907 info->dev_state_path,
908 "%d", XenbusStateClosed);
909 }
910 break;
911 case VSCSIFRONT_OP_DEL_LUN:
912 if (device_state != XenbusStateClosing)
913 break;
914
915 sdev = scsi_device_lookup(info->host, chn, tgt, lun);
916 if (sdev) {
917 scsi_remove_device(sdev);
918 scsi_device_put(sdev);
919 }
920 break;
921 default:
922 break;
923 }
924 }
925
926 info->curr = NULL;
927
928 kfree(dir);
929}
930
931static void scsifront_read_backend_params(struct xenbus_device *dev,
932 struct vscsifrnt_info *info)
933{
934 unsigned int sg_grant;
935 int ret;
936 struct Scsi_Host *host = info->host;
937
938 ret = xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg-grant", "%u",
939 &sg_grant);
940 if (ret == 1 && sg_grant) {
941 sg_grant = min_t(unsigned int, sg_grant, SG_ALL);
942 sg_grant = max_t(unsigned int, sg_grant, VSCSIIF_SG_TABLESIZE);
943 host->sg_tablesize = min_t(unsigned int, sg_grant,
944 VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
945 sizeof(struct scsiif_request_segment));
946 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
947 }
948 dev_info(&dev->dev, "using up to %d SG entries\n", host->sg_tablesize);
949}
950
951static void scsifront_backend_changed(struct xenbus_device *dev,
952 enum xenbus_state backend_state)
953{
954 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
955
956 pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
957
958 switch (backend_state) {
959 case XenbusStateUnknown:
960 case XenbusStateInitialising:
961 case XenbusStateInitWait:
962 case XenbusStateInitialised:
963 break;
964
965 case XenbusStateConnected:
966 scsifront_read_backend_params(dev, info);
967 if (xenbus_read_driver_state(dev->nodename) ==
968 XenbusStateInitialised)
969 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
970
971 if (dev->state != XenbusStateConnected)
972 xenbus_switch_state(dev, XenbusStateConnected);
973 break;
974
975 case XenbusStateClosed:
976 if (dev->state == XenbusStateClosed)
977 break;
978 /* Missed the backend's Closing state -- fallthrough */
979 case XenbusStateClosing:
980 scsifront_disconnect(info);
981 break;
982
983 case XenbusStateReconfiguring:
984 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
985 xenbus_switch_state(dev, XenbusStateReconfiguring);
986 break;
987
988 case XenbusStateReconfigured:
989 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
990 xenbus_switch_state(dev, XenbusStateConnected);
991 break;
992 }
993}
994
995static const struct xenbus_device_id scsifront_ids[] = {
996 { "vscsi" },
997 { "" }
998};
999
1000static DEFINE_XENBUS_DRIVER(scsifront, ,
1001 .probe = scsifront_probe,
1002 .remove = scsifront_remove,
1003 .otherend_changed = scsifront_backend_changed,
1004);
1005
1006static int __init scsifront_init(void)
1007{
1008 if (!xen_domain())
1009 return -ENODEV;
1010
1011 return xenbus_register_frontend(&scsifront_driver);
1012}
1013module_init(scsifront_init);
1014
1015static void __exit scsifront_exit(void)
1016{
1017 xenbus_unregister_driver(&scsifront_driver);
1018}
1019module_exit(scsifront_exit);
1020
1021MODULE_DESCRIPTION("Xen SCSI frontend driver");
1022MODULE_LICENSE("GPL");
1023MODULE_ALIAS("xen:vscsi");
1024MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");
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