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 #define VSCSIFRONT_OP_ADD_LUN 1
62 #define VSCSIFRONT_OP_DEL_LUN 2
63 #define VSCSIFRONT_OP_READD_LUN 3
64
65 /* Tuning point. */
66 #define VSCSIIF_DEFAULT_CMD_PER_LUN 10
67 #define VSCSIIF_MAX_TARGET 64
68 #define VSCSIIF_MAX_LUN 255
69
70 #define VSCSIIF_RING_SIZE __CONST_RING_SIZE(vscsiif, PAGE_SIZE)
71 #define VSCSIIF_MAX_REQS VSCSIIF_RING_SIZE
72
73 #define vscsiif_grants_sg(_sg) (PFN_UP((_sg) * \
74 sizeof(struct scsiif_request_segment)))
75
76 struct vscsifrnt_shadow {
77 /* command between backend and frontend */
78 unsigned char act;
79 uint8_t nr_segments;
80 uint16_t rqid;
81 uint16_t ref_rqid;
82
83 bool inflight;
84
85 unsigned int nr_grants; /* number of grants in gref[] */
86 struct scsiif_request_segment *sg; /* scatter/gather elements */
87 struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE];
88
89 /* Do reset or abort function. */
90 wait_queue_head_t wq_reset; /* reset work queue */
91 int wait_reset; /* reset work queue condition */
92 int32_t rslt_reset; /* reset response status: */
93 /* SUCCESS or FAILED or: */
94 #define RSLT_RESET_WAITING 0
95 #define RSLT_RESET_ERR -1
96
97 /* Requested struct scsi_cmnd is stored from kernel. */
98 struct scsi_cmnd *sc;
99 int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL];
100 };
101
102 struct vscsifrnt_info {
103 struct xenbus_device *dev;
104
105 struct Scsi_Host *host;
106 enum {
107 STATE_INACTIVE,
108 STATE_ACTIVE,
109 STATE_ERROR
110 } host_active;
111
112 unsigned int evtchn;
113 unsigned int irq;
114
115 grant_ref_t ring_ref;
116 struct vscsiif_front_ring ring;
117 struct vscsiif_response ring_rsp;
118
119 spinlock_t shadow_lock;
120 DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS);
121 struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS];
122
123 /* Following items are protected by the host lock. */
124 wait_queue_head_t wq_sync;
125 wait_queue_head_t wq_pause;
126 unsigned int wait_ring_available:1;
127 unsigned int waiting_pause:1;
128 unsigned int pause:1;
129 unsigned callers;
130
131 char dev_state_path[64];
132 struct task_struct *curr;
133 };
134
135 static DEFINE_MUTEX(scsifront_mutex);
136
scsifront_wake_up(struct vscsifrnt_info * info)137 static void scsifront_wake_up(struct vscsifrnt_info *info)
138 {
139 info->wait_ring_available = 0;
140 wake_up(&info->wq_sync);
141 }
142
scsifront_get_rqid(struct vscsifrnt_info * info)143 static int scsifront_get_rqid(struct vscsifrnt_info *info)
144 {
145 unsigned long flags;
146 int free;
147
148 spin_lock_irqsave(&info->shadow_lock, flags);
149
150 free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
151 __clear_bit(free, info->shadow_free_bitmap);
152
153 spin_unlock_irqrestore(&info->shadow_lock, flags);
154
155 return free;
156 }
157
_scsifront_put_rqid(struct vscsifrnt_info * info,uint32_t id)158 static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
159 {
160 int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
161
162 __set_bit(id, info->shadow_free_bitmap);
163 info->shadow[id] = NULL;
164
165 return empty || info->wait_ring_available;
166 }
167
scsifront_put_rqid(struct vscsifrnt_info * info,uint32_t id)168 static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
169 {
170 unsigned long flags;
171 int kick;
172
173 spin_lock_irqsave(&info->shadow_lock, flags);
174 kick = _scsifront_put_rqid(info, id);
175 spin_unlock_irqrestore(&info->shadow_lock, flags);
176
177 if (kick)
178 scsifront_wake_up(info);
179 }
180
scsifront_do_request(struct vscsifrnt_info * info,struct vscsifrnt_shadow * shadow)181 static int scsifront_do_request(struct vscsifrnt_info *info,
182 struct vscsifrnt_shadow *shadow)
183 {
184 struct vscsiif_front_ring *ring = &(info->ring);
185 struct vscsiif_request *ring_req;
186 struct scsi_cmnd *sc = shadow->sc;
187 uint32_t id;
188 int i, notify;
189
190 if (RING_FULL(&info->ring))
191 return -EBUSY;
192
193 id = scsifront_get_rqid(info); /* use id in response */
194 if (id >= VSCSIIF_MAX_REQS)
195 return -EBUSY;
196
197 info->shadow[id] = shadow;
198 shadow->rqid = id;
199
200 ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt);
201 ring->req_prod_pvt++;
202
203 ring_req->rqid = id;
204 ring_req->act = shadow->act;
205 ring_req->ref_rqid = shadow->ref_rqid;
206 ring_req->nr_segments = shadow->nr_segments;
207
208 ring_req->id = sc->device->id;
209 ring_req->lun = sc->device->lun;
210 ring_req->channel = sc->device->channel;
211 ring_req->cmd_len = sc->cmd_len;
212
213 BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE);
214
215 memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len);
216
217 ring_req->sc_data_direction = (uint8_t)sc->sc_data_direction;
218 ring_req->timeout_per_command = scsi_cmd_to_rq(sc)->timeout / HZ;
219
220 for (i = 0; i < (shadow->nr_segments & ~VSCSIIF_SG_GRANT); i++)
221 ring_req->seg[i] = shadow->seg[i];
222
223 shadow->inflight = true;
224
225 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify);
226 if (notify)
227 notify_remote_via_irq(info->irq);
228
229 return 0;
230 }
231
scsifront_set_error(struct vscsifrnt_info * info,const char * msg)232 static void scsifront_set_error(struct vscsifrnt_info *info, const char *msg)
233 {
234 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME "%s\n"
235 "Disabling device for further use\n", msg);
236 info->host_active = STATE_ERROR;
237 }
238
scsifront_gnttab_done(struct vscsifrnt_info * info,struct vscsifrnt_shadow * shadow)239 static void scsifront_gnttab_done(struct vscsifrnt_info *info,
240 struct vscsifrnt_shadow *shadow)
241 {
242 int i;
243
244 if (shadow->sc->sc_data_direction == DMA_NONE)
245 return;
246
247 for (i = 0; i < shadow->nr_grants; i++) {
248 if (unlikely(!gnttab_try_end_foreign_access(shadow->gref[i]))) {
249 scsifront_set_error(info, "grant still in use by backend");
250 return;
251 }
252 }
253
254 kfree(shadow->sg);
255 }
256
scsifront_host_byte(int32_t rslt)257 static unsigned int scsifront_host_byte(int32_t rslt)
258 {
259 switch (XEN_VSCSIIF_RSLT_HOST(rslt)) {
260 case XEN_VSCSIIF_RSLT_HOST_OK:
261 return DID_OK;
262 case XEN_VSCSIIF_RSLT_HOST_NO_CONNECT:
263 return DID_NO_CONNECT;
264 case XEN_VSCSIIF_RSLT_HOST_BUS_BUSY:
265 return DID_BUS_BUSY;
266 case XEN_VSCSIIF_RSLT_HOST_TIME_OUT:
267 return DID_TIME_OUT;
268 case XEN_VSCSIIF_RSLT_HOST_BAD_TARGET:
269 return DID_BAD_TARGET;
270 case XEN_VSCSIIF_RSLT_HOST_ABORT:
271 return DID_ABORT;
272 case XEN_VSCSIIF_RSLT_HOST_PARITY:
273 return DID_PARITY;
274 case XEN_VSCSIIF_RSLT_HOST_ERROR:
275 return DID_ERROR;
276 case XEN_VSCSIIF_RSLT_HOST_RESET:
277 return DID_RESET;
278 case XEN_VSCSIIF_RSLT_HOST_BAD_INTR:
279 return DID_BAD_INTR;
280 case XEN_VSCSIIF_RSLT_HOST_PASSTHROUGH:
281 return DID_PASSTHROUGH;
282 case XEN_VSCSIIF_RSLT_HOST_SOFT_ERROR:
283 return DID_SOFT_ERROR;
284 case XEN_VSCSIIF_RSLT_HOST_IMM_RETRY:
285 return DID_IMM_RETRY;
286 case XEN_VSCSIIF_RSLT_HOST_REQUEUE:
287 return DID_REQUEUE;
288 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_DISRUPTED:
289 return DID_TRANSPORT_DISRUPTED;
290 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_FAILFAST:
291 return DID_TRANSPORT_FAILFAST;
292 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_MARGINAL:
293 return DID_TRANSPORT_MARGINAL;
294 default:
295 return DID_ERROR;
296 }
297 }
298
scsifront_cdb_cmd_done(struct vscsifrnt_info * info,struct vscsiif_response * ring_rsp)299 static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info,
300 struct vscsiif_response *ring_rsp)
301 {
302 struct vscsifrnt_shadow *shadow;
303 struct scsi_cmnd *sc;
304 uint32_t id;
305 uint8_t sense_len;
306
307 id = ring_rsp->rqid;
308 shadow = info->shadow[id];
309 sc = shadow->sc;
310
311 BUG_ON(sc == NULL);
312
313 scsifront_gnttab_done(info, shadow);
314 if (info->host_active == STATE_ERROR)
315 return;
316 scsifront_put_rqid(info, id);
317
318 set_host_byte(sc, scsifront_host_byte(ring_rsp->rslt));
319 set_status_byte(sc, XEN_VSCSIIF_RSLT_STATUS(ring_rsp->rslt));
320 scsi_set_resid(sc, ring_rsp->residual_len);
321
322 sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE,
323 ring_rsp->sense_len);
324
325 if (sense_len)
326 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len);
327
328 scsi_done(sc);
329 }
330
scsifront_sync_cmd_done(struct vscsifrnt_info * info,struct vscsiif_response * ring_rsp)331 static void scsifront_sync_cmd_done(struct vscsifrnt_info *info,
332 struct vscsiif_response *ring_rsp)
333 {
334 uint16_t id = ring_rsp->rqid;
335 unsigned long flags;
336 struct vscsifrnt_shadow *shadow = info->shadow[id];
337 int kick;
338
339 spin_lock_irqsave(&info->shadow_lock, flags);
340 shadow->wait_reset = 1;
341 switch (shadow->rslt_reset) {
342 case RSLT_RESET_WAITING:
343 if (ring_rsp->rslt == XEN_VSCSIIF_RSLT_RESET_SUCCESS)
344 shadow->rslt_reset = SUCCESS;
345 else
346 shadow->rslt_reset = FAILED;
347 break;
348 case RSLT_RESET_ERR:
349 kick = _scsifront_put_rqid(info, id);
350 spin_unlock_irqrestore(&info->shadow_lock, flags);
351 kfree(shadow);
352 if (kick)
353 scsifront_wake_up(info);
354 return;
355 default:
356 scsifront_set_error(info, "bad reset state");
357 break;
358 }
359 spin_unlock_irqrestore(&info->shadow_lock, flags);
360
361 wake_up(&shadow->wq_reset);
362 }
363
scsifront_do_response(struct vscsifrnt_info * info,struct vscsiif_response * ring_rsp)364 static void scsifront_do_response(struct vscsifrnt_info *info,
365 struct vscsiif_response *ring_rsp)
366 {
367 struct vscsifrnt_shadow *shadow;
368
369 if (ring_rsp->rqid >= VSCSIIF_MAX_REQS ||
370 !info->shadow[ring_rsp->rqid]->inflight) {
371 scsifront_set_error(info, "illegal rqid returned by backend!");
372 return;
373 }
374 shadow = info->shadow[ring_rsp->rqid];
375 shadow->inflight = false;
376
377 if (shadow->act == VSCSIIF_ACT_SCSI_CDB)
378 scsifront_cdb_cmd_done(info, ring_rsp);
379 else
380 scsifront_sync_cmd_done(info, ring_rsp);
381 }
382
scsifront_ring_drain(struct vscsifrnt_info * info,unsigned int * eoiflag)383 static int scsifront_ring_drain(struct vscsifrnt_info *info,
384 unsigned int *eoiflag)
385 {
386 struct vscsiif_response ring_rsp;
387 RING_IDX i, rp;
388 int more_to_do = 0;
389
390 rp = READ_ONCE(info->ring.sring->rsp_prod);
391 virt_rmb(); /* ordering required respective to backend */
392 if (RING_RESPONSE_PROD_OVERFLOW(&info->ring, rp)) {
393 scsifront_set_error(info, "illegal number of responses");
394 return 0;
395 }
396 for (i = info->ring.rsp_cons; i != rp; i++) {
397 RING_COPY_RESPONSE(&info->ring, i, &ring_rsp);
398 scsifront_do_response(info, &ring_rsp);
399 if (info->host_active == STATE_ERROR)
400 return 0;
401 *eoiflag &= ~XEN_EOI_FLAG_SPURIOUS;
402 }
403
404 info->ring.rsp_cons = i;
405
406 if (i != info->ring.req_prod_pvt)
407 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
408 else
409 info->ring.sring->rsp_event = i + 1;
410
411 return more_to_do;
412 }
413
scsifront_cmd_done(struct vscsifrnt_info * info,unsigned int * eoiflag)414 static int scsifront_cmd_done(struct vscsifrnt_info *info,
415 unsigned int *eoiflag)
416 {
417 int more_to_do;
418 unsigned long flags;
419
420 spin_lock_irqsave(info->host->host_lock, flags);
421
422 more_to_do = scsifront_ring_drain(info, eoiflag);
423
424 info->wait_ring_available = 0;
425
426 spin_unlock_irqrestore(info->host->host_lock, flags);
427
428 wake_up(&info->wq_sync);
429
430 return more_to_do;
431 }
432
scsifront_irq_fn(int irq,void * dev_id)433 static irqreturn_t scsifront_irq_fn(int irq, void *dev_id)
434 {
435 struct vscsifrnt_info *info = dev_id;
436 unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS;
437
438 if (info->host_active == STATE_ERROR) {
439 xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
440 return IRQ_HANDLED;
441 }
442
443 while (scsifront_cmd_done(info, &eoiflag))
444 /* Yield point for this unbounded loop. */
445 cond_resched();
446
447 xen_irq_lateeoi(irq, eoiflag);
448
449 return IRQ_HANDLED;
450 }
451
scsifront_finish_all(struct vscsifrnt_info * info)452 static void scsifront_finish_all(struct vscsifrnt_info *info)
453 {
454 unsigned int i, dummy;
455 struct vscsiif_response resp;
456
457 scsifront_ring_drain(info, &dummy);
458
459 for (i = 0; i < VSCSIIF_MAX_REQS; i++) {
460 if (test_bit(i, info->shadow_free_bitmap))
461 continue;
462 resp.rqid = i;
463 resp.sense_len = 0;
464 resp.rslt = DID_RESET << 16;
465 resp.residual_len = 0;
466 scsifront_do_response(info, &resp);
467 }
468 }
469
map_data_for_request(struct vscsifrnt_info * info,struct scsi_cmnd * sc,struct vscsifrnt_shadow * shadow)470 static int map_data_for_request(struct vscsifrnt_info *info,
471 struct scsi_cmnd *sc,
472 struct vscsifrnt_shadow *shadow)
473 {
474 grant_ref_t gref_head;
475 struct page *page;
476 int err, ref, ref_cnt = 0;
477 int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE);
478 unsigned int i, off, len, bytes;
479 unsigned int data_len = scsi_bufflen(sc);
480 unsigned int data_grants = 0, seg_grants = 0;
481 struct scatterlist *sg;
482 struct scsiif_request_segment *seg;
483
484 if (sc->sc_data_direction == DMA_NONE || !data_len)
485 return 0;
486
487 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)
488 data_grants += PFN_UP(sg->offset + sg->length);
489
490 if (data_grants > VSCSIIF_SG_TABLESIZE) {
491 if (data_grants > info->host->sg_tablesize) {
492 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
493 "Unable to map request_buffer for command!\n");
494 return -E2BIG;
495 }
496 seg_grants = vscsiif_grants_sg(data_grants);
497 shadow->sg = kcalloc(data_grants,
498 sizeof(struct scsiif_request_segment), GFP_ATOMIC);
499 if (!shadow->sg)
500 return -ENOMEM;
501 }
502 seg = shadow->sg ? : shadow->seg;
503
504 err = gnttab_alloc_grant_references(seg_grants + data_grants,
505 &gref_head);
506 if (err) {
507 kfree(shadow->sg);
508 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
509 "gnttab_alloc_grant_references() error\n");
510 return -ENOMEM;
511 }
512
513 if (seg_grants) {
514 page = virt_to_page(seg);
515 off = offset_in_page(seg);
516 len = sizeof(struct scsiif_request_segment) * data_grants;
517 while (len > 0) {
518 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
519
520 ref = gnttab_claim_grant_reference(&gref_head);
521 BUG_ON(ref == -ENOSPC);
522
523 gnttab_grant_foreign_access_ref(ref,
524 info->dev->otherend_id,
525 xen_page_to_gfn(page), 1);
526 shadow->gref[ref_cnt] = ref;
527 shadow->seg[ref_cnt].gref = ref;
528 shadow->seg[ref_cnt].offset = (uint16_t)off;
529 shadow->seg[ref_cnt].length = (uint16_t)bytes;
530
531 page++;
532 len -= bytes;
533 off = 0;
534 ref_cnt++;
535 }
536 BUG_ON(seg_grants < ref_cnt);
537 seg_grants = ref_cnt;
538 }
539
540 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {
541 page = sg_page(sg);
542 off = sg->offset;
543 len = sg->length;
544
545 while (len > 0 && data_len > 0) {
546 /*
547 * sg sends a scatterlist that is larger than
548 * the data_len it wants transferred for certain
549 * IO sizes.
550 */
551 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
552 bytes = min(bytes, data_len);
553
554 ref = gnttab_claim_grant_reference(&gref_head);
555 BUG_ON(ref == -ENOSPC);
556
557 gnttab_grant_foreign_access_ref(ref,
558 info->dev->otherend_id,
559 xen_page_to_gfn(page),
560 grant_ro);
561
562 shadow->gref[ref_cnt] = ref;
563 seg->gref = ref;
564 seg->offset = (uint16_t)off;
565 seg->length = (uint16_t)bytes;
566
567 page++;
568 seg++;
569 len -= bytes;
570 data_len -= bytes;
571 off = 0;
572 ref_cnt++;
573 }
574 }
575
576 if (seg_grants)
577 shadow->nr_segments = VSCSIIF_SG_GRANT | seg_grants;
578 else
579 shadow->nr_segments = (uint8_t)ref_cnt;
580 shadow->nr_grants = ref_cnt;
581
582 return 0;
583 }
584
scsifront_enter(struct vscsifrnt_info * info)585 static int scsifront_enter(struct vscsifrnt_info *info)
586 {
587 if (info->pause)
588 return 1;
589 info->callers++;
590 return 0;
591 }
592
scsifront_return(struct vscsifrnt_info * info)593 static void scsifront_return(struct vscsifrnt_info *info)
594 {
595 info->callers--;
596 if (info->callers)
597 return;
598
599 if (!info->waiting_pause)
600 return;
601
602 info->waiting_pause = 0;
603 wake_up(&info->wq_pause);
604 }
605
scsifront_queuecommand(struct Scsi_Host * shost,struct scsi_cmnd * sc)606 static int scsifront_queuecommand(struct Scsi_Host *shost,
607 struct scsi_cmnd *sc)
608 {
609 struct vscsifrnt_info *info = shost_priv(shost);
610 struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc);
611 unsigned long flags;
612 int err;
613
614 if (info->host_active == STATE_ERROR)
615 return SCSI_MLQUEUE_HOST_BUSY;
616
617 sc->result = 0;
618
619 shadow->sc = sc;
620 shadow->act = VSCSIIF_ACT_SCSI_CDB;
621
622 spin_lock_irqsave(shost->host_lock, flags);
623 if (scsifront_enter(info)) {
624 spin_unlock_irqrestore(shost->host_lock, flags);
625 return SCSI_MLQUEUE_HOST_BUSY;
626 }
627
628 err = map_data_for_request(info, sc, shadow);
629 if (err < 0) {
630 pr_debug("%s: err %d\n", __func__, err);
631 scsifront_return(info);
632 spin_unlock_irqrestore(shost->host_lock, flags);
633 if (err == -ENOMEM)
634 return SCSI_MLQUEUE_HOST_BUSY;
635 sc->result = DID_ERROR << 16;
636 scsi_done(sc);
637 return 0;
638 }
639
640 if (scsifront_do_request(info, shadow)) {
641 scsifront_gnttab_done(info, shadow);
642 goto busy;
643 }
644
645 scsifront_return(info);
646 spin_unlock_irqrestore(shost->host_lock, flags);
647
648 return 0;
649
650 busy:
651 scsifront_return(info);
652 spin_unlock_irqrestore(shost->host_lock, flags);
653 pr_debug("%s: busy\n", __func__);
654 return SCSI_MLQUEUE_HOST_BUSY;
655 }
656
657 /*
658 * Any exception handling (reset or abort) must be forwarded to the backend.
659 * We have to wait until an answer is returned. This answer contains the
660 * result to be returned to the requestor.
661 */
scsifront_action_handler(struct scsi_cmnd * sc,uint8_t act)662 static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)
663 {
664 struct Scsi_Host *host = sc->device->host;
665 struct vscsifrnt_info *info = shost_priv(host);
666 struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
667 int err = 0;
668
669 if (info->host_active == STATE_ERROR)
670 return FAILED;
671
672 shadow = kzalloc(sizeof(*shadow), GFP_NOIO);
673 if (!shadow)
674 return FAILED;
675
676 shadow->act = act;
677 shadow->rslt_reset = RSLT_RESET_WAITING;
678 shadow->sc = sc;
679 shadow->ref_rqid = s->rqid;
680 init_waitqueue_head(&shadow->wq_reset);
681
682 spin_lock_irq(host->host_lock);
683
684 for (;;) {
685 if (scsifront_enter(info))
686 goto fail;
687
688 if (!scsifront_do_request(info, shadow))
689 break;
690
691 scsifront_return(info);
692 if (err)
693 goto fail;
694 info->wait_ring_available = 1;
695 spin_unlock_irq(host->host_lock);
696 err = wait_event_interruptible(info->wq_sync,
697 !info->wait_ring_available);
698 spin_lock_irq(host->host_lock);
699 }
700
701 spin_unlock_irq(host->host_lock);
702 err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
703 spin_lock_irq(host->host_lock);
704
705 if (!err) {
706 err = shadow->rslt_reset;
707 scsifront_put_rqid(info, shadow->rqid);
708 kfree(shadow);
709 } else {
710 spin_lock(&info->shadow_lock);
711 shadow->rslt_reset = RSLT_RESET_ERR;
712 spin_unlock(&info->shadow_lock);
713 err = FAILED;
714 }
715
716 scsifront_return(info);
717 spin_unlock_irq(host->host_lock);
718 return err;
719
720 fail:
721 spin_unlock_irq(host->host_lock);
722 kfree(shadow);
723 return FAILED;
724 }
725
scsifront_eh_abort_handler(struct scsi_cmnd * sc)726 static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
727 {
728 pr_debug("%s\n", __func__);
729 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);
730 }
731
scsifront_dev_reset_handler(struct scsi_cmnd * sc)732 static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
733 {
734 pr_debug("%s\n", __func__);
735 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);
736 }
737
scsifront_sdev_configure(struct scsi_device * sdev)738 static int scsifront_sdev_configure(struct scsi_device *sdev)
739 {
740 struct vscsifrnt_info *info = shost_priv(sdev->host);
741 int err;
742
743 if (info->host_active == STATE_ERROR)
744 return -EIO;
745
746 if (current == info->curr) {
747 err = xenbus_printf(XBT_NIL, info->dev->nodename,
748 info->dev_state_path, "%d", XenbusStateConnected);
749 if (err) {
750 xenbus_dev_error(info->dev, err,
751 "%s: writing dev_state_path", __func__);
752 return err;
753 }
754 }
755
756 return 0;
757 }
758
scsifront_sdev_destroy(struct scsi_device * sdev)759 static void scsifront_sdev_destroy(struct scsi_device *sdev)
760 {
761 struct vscsifrnt_info *info = shost_priv(sdev->host);
762 int err;
763
764 if (current == info->curr) {
765 err = xenbus_printf(XBT_NIL, info->dev->nodename,
766 info->dev_state_path, "%d", XenbusStateClosed);
767 if (err)
768 xenbus_dev_error(info->dev, err,
769 "%s: writing dev_state_path", __func__);
770 }
771 }
772
773 static const struct scsi_host_template scsifront_sht = {
774 .module = THIS_MODULE,
775 .name = "Xen SCSI frontend driver",
776 .queuecommand = scsifront_queuecommand,
777 .eh_abort_handler = scsifront_eh_abort_handler,
778 .eh_device_reset_handler = scsifront_dev_reset_handler,
779 .slave_configure = scsifront_sdev_configure,
780 .slave_destroy = scsifront_sdev_destroy,
781 .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN,
782 .can_queue = VSCSIIF_MAX_REQS,
783 .this_id = -1,
784 .cmd_size = sizeof(struct vscsifrnt_shadow),
785 .sg_tablesize = VSCSIIF_SG_TABLESIZE,
786 .proc_name = "scsifront",
787 };
788
scsifront_alloc_ring(struct vscsifrnt_info * info)789 static int scsifront_alloc_ring(struct vscsifrnt_info *info)
790 {
791 struct xenbus_device *dev = info->dev;
792 struct vscsiif_sring *sring;
793 int err;
794
795 /***** Frontend to Backend ring start *****/
796 err = xenbus_setup_ring(dev, GFP_KERNEL, (void **)&sring, 1,
797 &info->ring_ref);
798 if (err)
799 return err;
800
801 XEN_FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
802
803 err = xenbus_alloc_evtchn(dev, &info->evtchn);
804 if (err) {
805 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
806 goto free_gnttab;
807 }
808
809 err = bind_evtchn_to_irq_lateeoi(info->evtchn);
810 if (err <= 0) {
811 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
812 goto free_gnttab;
813 }
814
815 info->irq = err;
816
817 err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
818 IRQF_ONESHOT, "scsifront", info);
819 if (err) {
820 xenbus_dev_fatal(dev, err, "request_threaded_irq");
821 goto free_irq;
822 }
823
824 return 0;
825
826 /* free resource */
827 free_irq:
828 unbind_from_irqhandler(info->irq, info);
829 free_gnttab:
830 xenbus_teardown_ring((void **)&sring, 1, &info->ring_ref);
831
832 return err;
833 }
834
scsifront_free_ring(struct vscsifrnt_info * info)835 static void scsifront_free_ring(struct vscsifrnt_info *info)
836 {
837 unbind_from_irqhandler(info->irq, info);
838 xenbus_teardown_ring((void **)&info->ring.sring, 1, &info->ring_ref);
839 }
840
scsifront_init_ring(struct vscsifrnt_info * info)841 static int scsifront_init_ring(struct vscsifrnt_info *info)
842 {
843 struct xenbus_device *dev = info->dev;
844 struct xenbus_transaction xbt;
845 int err;
846
847 pr_debug("%s\n", __func__);
848
849 err = scsifront_alloc_ring(info);
850 if (err)
851 return err;
852 pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
853
854 again:
855 err = xenbus_transaction_start(&xbt);
856 if (err)
857 xenbus_dev_fatal(dev, err, "starting transaction");
858
859 err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
860 info->ring_ref);
861 if (err) {
862 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
863 goto fail;
864 }
865
866 err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
867 info->evtchn);
868
869 if (err) {
870 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
871 goto fail;
872 }
873
874 err = xenbus_transaction_end(xbt, 0);
875 if (err) {
876 if (err == -EAGAIN)
877 goto again;
878 xenbus_dev_fatal(dev, err, "completing transaction");
879 goto free_sring;
880 }
881
882 return 0;
883
884 fail:
885 xenbus_transaction_end(xbt, 1);
886 free_sring:
887 scsifront_free_ring(info);
888
889 return err;
890 }
891
892
scsifront_probe(struct xenbus_device * dev,const struct xenbus_device_id * id)893 static int scsifront_probe(struct xenbus_device *dev,
894 const struct xenbus_device_id *id)
895 {
896 struct vscsifrnt_info *info;
897 struct Scsi_Host *host;
898 int err = -ENOMEM;
899 char name[TASK_COMM_LEN];
900
901 host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
902 if (!host) {
903 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
904 return err;
905 }
906 info = shost_priv(host);
907
908 dev_set_drvdata(&dev->dev, info);
909 info->dev = dev;
910
911 bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
912
913 err = scsifront_init_ring(info);
914 if (err) {
915 scsi_host_put(host);
916 return err;
917 }
918
919 init_waitqueue_head(&info->wq_sync);
920 init_waitqueue_head(&info->wq_pause);
921 spin_lock_init(&info->shadow_lock);
922
923 snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
924
925 host->max_id = VSCSIIF_MAX_TARGET;
926 host->max_channel = 0;
927 host->max_lun = VSCSIIF_MAX_LUN;
928 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
929 host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
930
931 err = scsi_add_host(host, &dev->dev);
932 if (err) {
933 dev_err(&dev->dev, "fail to add scsi host %d\n", err);
934 goto free_sring;
935 }
936 info->host = host;
937 info->host_active = STATE_ACTIVE;
938
939 xenbus_switch_state(dev, XenbusStateInitialised);
940
941 return 0;
942
943 free_sring:
944 scsifront_free_ring(info);
945 scsi_host_put(host);
946 return err;
947 }
948
scsifront_resume(struct xenbus_device * dev)949 static int scsifront_resume(struct xenbus_device *dev)
950 {
951 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
952 struct Scsi_Host *host = info->host;
953 int err;
954
955 spin_lock_irq(host->host_lock);
956
957 /* Finish all still pending commands. */
958 scsifront_finish_all(info);
959
960 spin_unlock_irq(host->host_lock);
961
962 /* Reconnect to dom0. */
963 scsifront_free_ring(info);
964 err = scsifront_init_ring(info);
965 if (err) {
966 dev_err(&dev->dev, "fail to resume %d\n", err);
967 scsi_host_put(host);
968 return err;
969 }
970
971 xenbus_switch_state(dev, XenbusStateInitialised);
972
973 return 0;
974 }
975
scsifront_suspend(struct xenbus_device * dev)976 static int scsifront_suspend(struct xenbus_device *dev)
977 {
978 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
979 struct Scsi_Host *host = info->host;
980 int err = 0;
981
982 /* No new commands for the backend. */
983 spin_lock_irq(host->host_lock);
984 info->pause = 1;
985 while (info->callers && !err) {
986 info->waiting_pause = 1;
987 info->wait_ring_available = 0;
988 spin_unlock_irq(host->host_lock);
989 wake_up(&info->wq_sync);
990 err = wait_event_interruptible(info->wq_pause,
991 !info->waiting_pause);
992 spin_lock_irq(host->host_lock);
993 }
994 spin_unlock_irq(host->host_lock);
995 return err;
996 }
997
scsifront_remove(struct xenbus_device * dev)998 static void scsifront_remove(struct xenbus_device *dev)
999 {
1000 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1001
1002 pr_debug("%s: %s removed\n", __func__, dev->nodename);
1003
1004 mutex_lock(&scsifront_mutex);
1005 if (info->host_active != STATE_INACTIVE) {
1006 /* Scsi_host not yet removed */
1007 scsi_remove_host(info->host);
1008 info->host_active = STATE_INACTIVE;
1009 }
1010 mutex_unlock(&scsifront_mutex);
1011
1012 scsifront_free_ring(info);
1013 scsi_host_put(info->host);
1014 }
1015
scsifront_disconnect(struct vscsifrnt_info * info)1016 static void scsifront_disconnect(struct vscsifrnt_info *info)
1017 {
1018 struct xenbus_device *dev = info->dev;
1019 struct Scsi_Host *host = info->host;
1020
1021 pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
1022
1023 /*
1024 * When this function is executed, all devices of
1025 * Frontend have been deleted.
1026 * Therefore, it need not block I/O before remove_host.
1027 */
1028
1029 mutex_lock(&scsifront_mutex);
1030 if (info->host_active != STATE_INACTIVE) {
1031 scsi_remove_host(host);
1032 info->host_active = STATE_INACTIVE;
1033 }
1034 mutex_unlock(&scsifront_mutex);
1035
1036 xenbus_frontend_closed(dev);
1037 }
1038
scsifront_do_lun_hotplug(struct vscsifrnt_info * info,int op)1039 static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
1040 {
1041 struct xenbus_device *dev = info->dev;
1042 int i, err = 0;
1043 char str[64];
1044 char **dir;
1045 unsigned int dir_n = 0;
1046 unsigned int device_state;
1047 unsigned int hst, chn, tgt, lun;
1048 struct scsi_device *sdev;
1049
1050 if (info->host_active == STATE_ERROR)
1051 return;
1052
1053 dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
1054 if (IS_ERR(dir))
1055 return;
1056
1057 /* mark current task as the one allowed to modify device states */
1058 BUG_ON(info->curr);
1059 info->curr = current;
1060
1061 for (i = 0; i < dir_n; i++) {
1062 /* read status */
1063 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
1064 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
1065 &device_state);
1066 if (XENBUS_EXIST_ERR(err))
1067 continue;
1068
1069 /* virtual SCSI device */
1070 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
1071 err = xenbus_scanf(XBT_NIL, dev->otherend, str,
1072 "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
1073 if (XENBUS_EXIST_ERR(err))
1074 continue;
1075
1076 /*
1077 * Front device state path, used in slave_configure called
1078 * on successfull scsi_add_device, and in slave_destroy called
1079 * on remove of a device.
1080 */
1081 snprintf(info->dev_state_path, sizeof(info->dev_state_path),
1082 "vscsi-devs/%s/state", dir[i]);
1083
1084 switch (op) {
1085 case VSCSIFRONT_OP_ADD_LUN:
1086 if (device_state != XenbusStateInitialised)
1087 break;
1088
1089 if (scsi_add_device(info->host, chn, tgt, lun)) {
1090 dev_err(&dev->dev, "scsi_add_device\n");
1091 err = xenbus_printf(XBT_NIL, dev->nodename,
1092 info->dev_state_path,
1093 "%d", XenbusStateClosed);
1094 if (err)
1095 xenbus_dev_error(dev, err,
1096 "%s: writing dev_state_path", __func__);
1097 }
1098 break;
1099 case VSCSIFRONT_OP_DEL_LUN:
1100 if (device_state != XenbusStateClosing)
1101 break;
1102
1103 sdev = scsi_device_lookup(info->host, chn, tgt, lun);
1104 if (sdev) {
1105 scsi_remove_device(sdev);
1106 scsi_device_put(sdev);
1107 }
1108 break;
1109 case VSCSIFRONT_OP_READD_LUN:
1110 if (device_state == XenbusStateConnected) {
1111 err = xenbus_printf(XBT_NIL, dev->nodename,
1112 info->dev_state_path,
1113 "%d", XenbusStateConnected);
1114 if (err)
1115 xenbus_dev_error(dev, err,
1116 "%s: writing dev_state_path", __func__);
1117 }
1118 break;
1119 default:
1120 break;
1121 }
1122 }
1123
1124 info->curr = NULL;
1125
1126 kfree(dir);
1127 }
1128
scsifront_read_backend_params(struct xenbus_device * dev,struct vscsifrnt_info * info)1129 static void scsifront_read_backend_params(struct xenbus_device *dev,
1130 struct vscsifrnt_info *info)
1131 {
1132 unsigned int sg_grant, nr_segs;
1133 struct Scsi_Host *host = info->host;
1134
1135 sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0);
1136 nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
1137 nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
1138 nr_segs = min_t(unsigned int, nr_segs,
1139 VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
1140 sizeof(struct scsiif_request_segment));
1141
1142 if (!info->pause && sg_grant)
1143 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);
1144 else if (info->pause && nr_segs < host->sg_tablesize)
1145 dev_warn(&dev->dev,
1146 "SG entries decreased from %d to %u - device may not work properly anymore\n",
1147 host->sg_tablesize, nr_segs);
1148
1149 host->sg_tablesize = nr_segs;
1150 host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;
1151 }
1152
scsifront_backend_changed(struct xenbus_device * dev,enum xenbus_state backend_state)1153 static void scsifront_backend_changed(struct xenbus_device *dev,
1154 enum xenbus_state backend_state)
1155 {
1156 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1157
1158 pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
1159
1160 switch (backend_state) {
1161 case XenbusStateUnknown:
1162 case XenbusStateInitialising:
1163 case XenbusStateInitWait:
1164 case XenbusStateInitialised:
1165 break;
1166
1167 case XenbusStateConnected:
1168 scsifront_read_backend_params(dev, info);
1169
1170 if (info->pause) {
1171 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);
1172 xenbus_switch_state(dev, XenbusStateConnected);
1173 info->pause = 0;
1174 return;
1175 }
1176
1177 if (xenbus_read_driver_state(dev->nodename) ==
1178 XenbusStateInitialised)
1179 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1180
1181 if (dev->state != XenbusStateConnected)
1182 xenbus_switch_state(dev, XenbusStateConnected);
1183 break;
1184
1185 case XenbusStateClosed:
1186 if (dev->state == XenbusStateClosed)
1187 break;
1188 fallthrough; /* Missed the backend's Closing state */
1189 case XenbusStateClosing:
1190 scsifront_disconnect(info);
1191 break;
1192
1193 case XenbusStateReconfiguring:
1194 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
1195 xenbus_switch_state(dev, XenbusStateReconfiguring);
1196 break;
1197
1198 case XenbusStateReconfigured:
1199 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1200 xenbus_switch_state(dev, XenbusStateConnected);
1201 break;
1202 }
1203 }
1204
1205 static const struct xenbus_device_id scsifront_ids[] = {
1206 { "vscsi" },
1207 { "" }
1208 };
1209
1210 static struct xenbus_driver scsifront_driver = {
1211 .ids = scsifront_ids,
1212 .probe = scsifront_probe,
1213 .remove = scsifront_remove,
1214 .resume = scsifront_resume,
1215 .suspend = scsifront_suspend,
1216 .otherend_changed = scsifront_backend_changed,
1217 };
1218
scsifront_init(void)1219 static int __init scsifront_init(void)
1220 {
1221 if (!xen_domain())
1222 return -ENODEV;
1223
1224 return xenbus_register_frontend(&scsifront_driver);
1225 }
1226 module_init(scsifront_init);
1227
scsifront_exit(void)1228 static void __exit scsifront_exit(void)
1229 {
1230 xenbus_unregister_driver(&scsifront_driver);
1231 }
1232 module_exit(scsifront_exit);
1233
1234 MODULE_DESCRIPTION("Xen SCSI frontend driver");
1235 MODULE_LICENSE("GPL");
1236 MODULE_ALIAS("xen:vscsi");
1237 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");
1238