2 * Xen SCSI frontend driver
4 * Copyright (c) 2008, FUJITSU Limited
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:
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:
19 * The above copyright notice and this permission notice shall be included in
20 * all copies or substantial portions of the Software.
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
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>
44 #include <scsi/scsi_cmnd.h>
45 #include <scsi/scsi_device.h>
46 #include <scsi/scsi.h>
47 #include <scsi/scsi_host.h>
50 #include <xen/xenbus.h>
51 #include <xen/grant_table.h>
52 #include <xen/events.h>
55 #include <xen/interface/grant_table.h>
56 #include <xen/interface/io/vscsiif.h>
57 #include <xen/interface/io/protocols.h>
59 #include <asm/xen/hypervisor.h>
62 #define GRANT_INVALID_REF 0
64 #define VSCSIFRONT_OP_ADD_LUN 1
65 #define VSCSIFRONT_OP_DEL_LUN 2
66 #define VSCSIFRONT_OP_READD_LUN 3
69 #define VSCSIIF_DEFAULT_CMD_PER_LUN 10
70 #define VSCSIIF_MAX_TARGET 64
71 #define VSCSIIF_MAX_LUN 255
73 #define VSCSIIF_RING_SIZE __CONST_RING_SIZE(vscsiif, PAGE_SIZE)
74 #define VSCSIIF_MAX_REQS VSCSIIF_RING_SIZE
76 #define vscsiif_grants_sg(_sg) (PFN_UP((_sg) * \
77 sizeof(struct scsiif_request_segment)))
79 struct vscsifrnt_shadow {
80 /* command between backend and frontend */
84 unsigned int nr_grants; /* number of grants in gref[] */
85 struct scsiif_request_segment *sg; /* scatter/gather elements */
87 /* Do reset or abort function. */
88 wait_queue_head_t wq_reset; /* reset work queue */
89 int wait_reset; /* reset work queue condition */
90 int32_t rslt_reset; /* reset response status: */
91 /* SUCCESS or FAILED or: */
92 #define RSLT_RESET_WAITING 0
93 #define RSLT_RESET_ERR -1
95 /* Requested struct scsi_cmnd is stored from kernel. */
97 int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL];
100 struct vscsifrnt_info {
101 struct xenbus_device *dev;
103 struct Scsi_Host *host;
109 grant_ref_t ring_ref;
110 struct vscsiif_front_ring ring;
111 struct vscsiif_response ring_rsp;
113 spinlock_t shadow_lock;
114 DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS);
115 struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS];
117 /* Following items are protected by the host lock. */
118 wait_queue_head_t wq_sync;
119 wait_queue_head_t wq_pause;
120 unsigned int wait_ring_available:1;
121 unsigned int waiting_pause:1;
122 unsigned int pause:1;
125 char dev_state_path[64];
126 struct task_struct *curr;
129 static DEFINE_MUTEX(scsifront_mutex);
131 static void scsifront_wake_up(struct vscsifrnt_info *info)
133 info->wait_ring_available = 0;
134 wake_up(&info->wq_sync);
137 static int scsifront_get_rqid(struct vscsifrnt_info *info)
142 spin_lock_irqsave(&info->shadow_lock, flags);
144 free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
145 __clear_bit(free, info->shadow_free_bitmap);
147 spin_unlock_irqrestore(&info->shadow_lock, flags);
152 static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
154 int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
156 __set_bit(id, info->shadow_free_bitmap);
157 info->shadow[id] = NULL;
159 return empty || info->wait_ring_available;
162 static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
167 spin_lock_irqsave(&info->shadow_lock, flags);
168 kick = _scsifront_put_rqid(info, id);
169 spin_unlock_irqrestore(&info->shadow_lock, flags);
172 scsifront_wake_up(info);
175 static struct vscsiif_request *scsifront_pre_req(struct vscsifrnt_info *info)
177 struct vscsiif_front_ring *ring = &(info->ring);
178 struct vscsiif_request *ring_req;
181 id = scsifront_get_rqid(info); /* use id in response */
182 if (id >= VSCSIIF_MAX_REQS)
185 ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt);
187 ring->req_prod_pvt++;
189 ring_req->rqid = (uint16_t)id;
194 static void scsifront_do_request(struct vscsifrnt_info *info)
196 struct vscsiif_front_ring *ring = &(info->ring);
199 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify);
201 notify_remote_via_irq(info->irq);
204 static void scsifront_gnttab_done(struct vscsifrnt_info *info, uint32_t id)
206 struct vscsifrnt_shadow *s = info->shadow[id];
209 if (s->sc->sc_data_direction == DMA_NONE)
212 for (i = 0; i < s->nr_grants; i++) {
213 if (unlikely(!gnttab_try_end_foreign_access(s->gref[i]))) {
214 shost_printk(KERN_ALERT, info->host, KBUILD_MODNAME
215 "grant still in use by backend\n");
223 static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info,
224 struct vscsiif_response *ring_rsp)
226 struct scsi_cmnd *sc;
231 sc = info->shadow[id]->sc;
235 scsifront_gnttab_done(info, id);
236 scsifront_put_rqid(info, id);
238 sc->result = ring_rsp->rslt;
239 scsi_set_resid(sc, ring_rsp->residual_len);
241 sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE,
242 ring_rsp->sense_len);
245 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len);
250 static void scsifront_sync_cmd_done(struct vscsifrnt_info *info,
251 struct vscsiif_response *ring_rsp)
253 uint16_t id = ring_rsp->rqid;
255 struct vscsifrnt_shadow *shadow = info->shadow[id];
258 spin_lock_irqsave(&info->shadow_lock, flags);
259 shadow->wait_reset = 1;
260 switch (shadow->rslt_reset) {
261 case RSLT_RESET_WAITING:
262 shadow->rslt_reset = ring_rsp->rslt;
265 kick = _scsifront_put_rqid(info, id);
266 spin_unlock_irqrestore(&info->shadow_lock, flags);
269 scsifront_wake_up(info);
272 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
273 "bad reset state %d, possibly leaking %u\n",
274 shadow->rslt_reset, id);
277 spin_unlock_irqrestore(&info->shadow_lock, flags);
279 wake_up(&shadow->wq_reset);
282 static void scsifront_do_response(struct vscsifrnt_info *info,
283 struct vscsiif_response *ring_rsp)
285 if (WARN(ring_rsp->rqid >= VSCSIIF_MAX_REQS ||
286 test_bit(ring_rsp->rqid, info->shadow_free_bitmap),
287 "illegal rqid %u returned by backend!\n", ring_rsp->rqid))
290 if (info->shadow[ring_rsp->rqid]->act == VSCSIIF_ACT_SCSI_CDB)
291 scsifront_cdb_cmd_done(info, ring_rsp);
293 scsifront_sync_cmd_done(info, ring_rsp);
296 static int scsifront_ring_drain(struct vscsifrnt_info *info)
298 struct vscsiif_response *ring_rsp;
302 rp = info->ring.sring->rsp_prod;
303 rmb(); /* ordering required respective to dom0 */
304 for (i = info->ring.rsp_cons; i != rp; i++) {
305 ring_rsp = RING_GET_RESPONSE(&info->ring, i);
306 scsifront_do_response(info, ring_rsp);
309 info->ring.rsp_cons = i;
311 if (i != info->ring.req_prod_pvt)
312 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
314 info->ring.sring->rsp_event = i + 1;
319 static int scsifront_cmd_done(struct vscsifrnt_info *info)
324 spin_lock_irqsave(info->host->host_lock, flags);
326 more_to_do = scsifront_ring_drain(info);
328 info->wait_ring_available = 0;
330 spin_unlock_irqrestore(info->host->host_lock, flags);
332 wake_up(&info->wq_sync);
337 static irqreturn_t scsifront_irq_fn(int irq, void *dev_id)
339 struct vscsifrnt_info *info = dev_id;
341 while (scsifront_cmd_done(info))
342 /* Yield point for this unbounded loop. */
348 static void scsifront_finish_all(struct vscsifrnt_info *info)
351 struct vscsiif_response resp;
353 scsifront_ring_drain(info);
355 for (i = 0; i < VSCSIIF_MAX_REQS; i++) {
356 if (test_bit(i, info->shadow_free_bitmap))
360 resp.rslt = DID_RESET << 16;
361 resp.residual_len = 0;
362 scsifront_do_response(info, &resp);
366 static int map_data_for_request(struct vscsifrnt_info *info,
367 struct scsi_cmnd *sc,
368 struct vscsiif_request *ring_req,
369 struct vscsifrnt_shadow *shadow)
371 grant_ref_t gref_head;
373 int err, ref, ref_cnt = 0;
374 int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE);
375 unsigned int i, off, len, bytes;
376 unsigned int data_len = scsi_bufflen(sc);
377 unsigned int data_grants = 0, seg_grants = 0;
378 struct scatterlist *sg;
379 struct scsiif_request_segment *seg;
381 ring_req->nr_segments = 0;
382 if (sc->sc_data_direction == DMA_NONE || !data_len)
385 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)
386 data_grants += PFN_UP(sg->offset + sg->length);
388 if (data_grants > VSCSIIF_SG_TABLESIZE) {
389 if (data_grants > info->host->sg_tablesize) {
390 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
391 "Unable to map request_buffer for command!\n");
394 seg_grants = vscsiif_grants_sg(data_grants);
395 shadow->sg = kcalloc(data_grants,
396 sizeof(struct scsiif_request_segment), GFP_ATOMIC);
400 seg = shadow->sg ? : ring_req->seg;
402 err = gnttab_alloc_grant_references(seg_grants + data_grants,
406 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
407 "gnttab_alloc_grant_references() error\n");
412 page = virt_to_page(seg);
413 off = (unsigned long)seg & ~PAGE_MASK;
414 len = sizeof(struct scsiif_request_segment) * data_grants;
416 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
418 ref = gnttab_claim_grant_reference(&gref_head);
419 BUG_ON(ref == -ENOSPC);
421 gnttab_grant_foreign_access_ref(ref,
422 info->dev->otherend_id,
423 xen_page_to_gfn(page), 1);
424 shadow->gref[ref_cnt] = ref;
425 ring_req->seg[ref_cnt].gref = ref;
426 ring_req->seg[ref_cnt].offset = (uint16_t)off;
427 ring_req->seg[ref_cnt].length = (uint16_t)bytes;
434 BUG_ON(seg_grants < ref_cnt);
435 seg_grants = ref_cnt;
438 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {
443 while (len > 0 && data_len > 0) {
445 * sg sends a scatterlist that is larger than
446 * the data_len it wants transferred for certain
449 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
450 bytes = min(bytes, data_len);
452 ref = gnttab_claim_grant_reference(&gref_head);
453 BUG_ON(ref == -ENOSPC);
455 gnttab_grant_foreign_access_ref(ref,
456 info->dev->otherend_id,
457 xen_page_to_gfn(page),
460 shadow->gref[ref_cnt] = ref;
462 seg->offset = (uint16_t)off;
463 seg->length = (uint16_t)bytes;
475 ring_req->nr_segments = VSCSIIF_SG_GRANT | seg_grants;
477 ring_req->nr_segments = (uint8_t)ref_cnt;
478 shadow->nr_grants = ref_cnt;
483 static struct vscsiif_request *scsifront_command2ring(
484 struct vscsifrnt_info *info, struct scsi_cmnd *sc,
485 struct vscsifrnt_shadow *shadow)
487 struct vscsiif_request *ring_req;
489 memset(shadow, 0, sizeof(*shadow));
491 ring_req = scsifront_pre_req(info);
495 info->shadow[ring_req->rqid] = shadow;
496 shadow->rqid = ring_req->rqid;
498 ring_req->id = sc->device->id;
499 ring_req->lun = sc->device->lun;
500 ring_req->channel = sc->device->channel;
501 ring_req->cmd_len = sc->cmd_len;
503 BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE);
505 memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len);
507 ring_req->sc_data_direction = (uint8_t)sc->sc_data_direction;
508 ring_req->timeout_per_command = sc->request->timeout / HZ;
513 static int scsifront_enter(struct vscsifrnt_info *info)
521 static void scsifront_return(struct vscsifrnt_info *info)
527 if (!info->waiting_pause)
530 info->waiting_pause = 0;
531 wake_up(&info->wq_pause);
534 static int scsifront_queuecommand(struct Scsi_Host *shost,
535 struct scsi_cmnd *sc)
537 struct vscsifrnt_info *info = shost_priv(shost);
538 struct vscsiif_request *ring_req;
539 struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc);
544 spin_lock_irqsave(shost->host_lock, flags);
545 if (scsifront_enter(info)) {
546 spin_unlock_irqrestore(shost->host_lock, flags);
547 return SCSI_MLQUEUE_HOST_BUSY;
549 if (RING_FULL(&info->ring))
552 ring_req = scsifront_command2ring(info, sc, shadow);
558 rqid = ring_req->rqid;
559 ring_req->act = VSCSIIF_ACT_SCSI_CDB;
562 shadow->act = VSCSIIF_ACT_SCSI_CDB;
564 err = map_data_for_request(info, sc, ring_req, shadow);
566 pr_debug("%s: err %d\n", __func__, err);
567 scsifront_put_rqid(info, rqid);
568 scsifront_return(info);
569 spin_unlock_irqrestore(shost->host_lock, flags);
571 return SCSI_MLQUEUE_HOST_BUSY;
572 sc->result = DID_ERROR << 16;
577 scsifront_do_request(info);
578 scsifront_return(info);
579 spin_unlock_irqrestore(shost->host_lock, flags);
584 scsifront_return(info);
585 spin_unlock_irqrestore(shost->host_lock, flags);
586 pr_debug("%s: busy\n", __func__);
587 return SCSI_MLQUEUE_HOST_BUSY;
591 * Any exception handling (reset or abort) must be forwarded to the backend.
592 * We have to wait until an answer is returned. This answer contains the
593 * result to be returned to the requestor.
595 static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)
597 struct Scsi_Host *host = sc->device->host;
598 struct vscsifrnt_info *info = shost_priv(host);
599 struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
600 struct vscsiif_request *ring_req;
603 shadow = kmalloc(sizeof(*shadow), GFP_NOIO);
607 spin_lock_irq(host->host_lock);
610 if (!RING_FULL(&info->ring)) {
611 ring_req = scsifront_command2ring(info, sc, shadow);
615 if (err || info->pause) {
616 spin_unlock_irq(host->host_lock);
620 info->wait_ring_available = 1;
621 spin_unlock_irq(host->host_lock);
622 err = wait_event_interruptible(info->wq_sync,
623 !info->wait_ring_available);
624 spin_lock_irq(host->host_lock);
627 if (scsifront_enter(info)) {
628 spin_unlock_irq(host->host_lock);
633 ring_req->ref_rqid = s->rqid;
636 shadow->rslt_reset = RSLT_RESET_WAITING;
637 init_waitqueue_head(&shadow->wq_reset);
639 ring_req->nr_segments = 0;
641 scsifront_do_request(info);
643 spin_unlock_irq(host->host_lock);
644 err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
645 spin_lock_irq(host->host_lock);
648 err = shadow->rslt_reset;
649 scsifront_put_rqid(info, shadow->rqid);
652 spin_lock(&info->shadow_lock);
653 shadow->rslt_reset = RSLT_RESET_ERR;
654 spin_unlock(&info->shadow_lock);
658 scsifront_return(info);
659 spin_unlock_irq(host->host_lock);
663 static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
665 pr_debug("%s\n", __func__);
666 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);
669 static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
671 pr_debug("%s\n", __func__);
672 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);
675 static int scsifront_sdev_configure(struct scsi_device *sdev)
677 struct vscsifrnt_info *info = shost_priv(sdev->host);
680 if (info && current == info->curr) {
681 err = xenbus_printf(XBT_NIL, info->dev->nodename,
682 info->dev_state_path, "%d", XenbusStateConnected);
684 xenbus_dev_error(info->dev, err,
685 "%s: writing dev_state_path", __func__);
693 static void scsifront_sdev_destroy(struct scsi_device *sdev)
695 struct vscsifrnt_info *info = shost_priv(sdev->host);
698 if (info && current == info->curr) {
699 err = xenbus_printf(XBT_NIL, info->dev->nodename,
700 info->dev_state_path, "%d", XenbusStateClosed);
702 xenbus_dev_error(info->dev, err,
703 "%s: writing dev_state_path", __func__);
707 static struct scsi_host_template scsifront_sht = {
708 .module = THIS_MODULE,
709 .name = "Xen SCSI frontend driver",
710 .queuecommand = scsifront_queuecommand,
711 .eh_abort_handler = scsifront_eh_abort_handler,
712 .eh_device_reset_handler = scsifront_dev_reset_handler,
713 .slave_configure = scsifront_sdev_configure,
714 .slave_destroy = scsifront_sdev_destroy,
715 .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN,
716 .can_queue = VSCSIIF_MAX_REQS,
718 .cmd_size = sizeof(struct vscsifrnt_shadow),
719 .sg_tablesize = VSCSIIF_SG_TABLESIZE,
720 .use_clustering = DISABLE_CLUSTERING,
721 .proc_name = "scsifront",
724 static int scsifront_alloc_ring(struct vscsifrnt_info *info)
726 struct xenbus_device *dev = info->dev;
727 struct vscsiif_sring *sring;
731 /***** Frontend to Backend ring start *****/
732 sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL);
734 xenbus_dev_fatal(dev, err,
735 "fail to allocate shared ring (Front to Back)");
738 SHARED_RING_INIT(sring);
739 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
741 err = xenbus_grant_ring(dev, sring, 1, &gref);
743 free_page((unsigned long)sring);
744 xenbus_dev_fatal(dev, err,
745 "fail to grant shared ring (Front to Back)");
748 info->ring_ref = gref;
750 err = xenbus_alloc_evtchn(dev, &info->evtchn);
752 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
756 err = bind_evtchn_to_irq(info->evtchn);
758 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
764 err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
765 IRQF_ONESHOT, "scsifront", info);
767 xenbus_dev_fatal(dev, err, "request_threaded_irq");
775 unbind_from_irqhandler(info->irq, info);
777 gnttab_end_foreign_access(info->ring_ref, 0,
778 (unsigned long)info->ring.sring);
783 static void scsifront_free_ring(struct vscsifrnt_info *info)
785 unbind_from_irqhandler(info->irq, info);
786 gnttab_end_foreign_access(info->ring_ref, 0,
787 (unsigned long)info->ring.sring);
790 static int scsifront_init_ring(struct vscsifrnt_info *info)
792 struct xenbus_device *dev = info->dev;
793 struct xenbus_transaction xbt;
796 pr_debug("%s\n", __func__);
798 err = scsifront_alloc_ring(info);
801 pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
804 err = xenbus_transaction_start(&xbt);
806 xenbus_dev_fatal(dev, err, "starting transaction");
808 err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
811 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
815 err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
819 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
823 err = xenbus_transaction_end(xbt, 0);
827 xenbus_dev_fatal(dev, err, "completing transaction");
834 xenbus_transaction_end(xbt, 1);
836 scsifront_free_ring(info);
842 static int scsifront_probe(struct xenbus_device *dev,
843 const struct xenbus_device_id *id)
845 struct vscsifrnt_info *info;
846 struct Scsi_Host *host;
848 char name[TASK_COMM_LEN];
850 host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
852 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
855 info = (struct vscsifrnt_info *)host->hostdata;
857 dev_set_drvdata(&dev->dev, info);
860 bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
862 err = scsifront_init_ring(info);
868 init_waitqueue_head(&info->wq_sync);
869 init_waitqueue_head(&info->wq_pause);
870 spin_lock_init(&info->shadow_lock);
872 snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
874 host->max_id = VSCSIIF_MAX_TARGET;
875 host->max_channel = 0;
876 host->max_lun = VSCSIIF_MAX_LUN;
877 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
878 host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
880 err = scsi_add_host(host, &dev->dev);
882 dev_err(&dev->dev, "fail to add scsi host %d\n", err);
886 info->host_active = 1;
888 xenbus_switch_state(dev, XenbusStateInitialised);
893 scsifront_free_ring(info);
898 static int scsifront_resume(struct xenbus_device *dev)
900 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
901 struct Scsi_Host *host = info->host;
904 spin_lock_irq(host->host_lock);
906 /* Finish all still pending commands. */
907 scsifront_finish_all(info);
909 spin_unlock_irq(host->host_lock);
911 /* Reconnect to dom0. */
912 scsifront_free_ring(info);
913 err = scsifront_init_ring(info);
915 dev_err(&dev->dev, "fail to resume %d\n", err);
920 xenbus_switch_state(dev, XenbusStateInitialised);
925 static int scsifront_suspend(struct xenbus_device *dev)
927 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
928 struct Scsi_Host *host = info->host;
931 /* No new commands for the backend. */
932 spin_lock_irq(host->host_lock);
934 while (info->callers && !err) {
935 info->waiting_pause = 1;
936 info->wait_ring_available = 0;
937 spin_unlock_irq(host->host_lock);
938 wake_up(&info->wq_sync);
939 err = wait_event_interruptible(info->wq_pause,
940 !info->waiting_pause);
941 spin_lock_irq(host->host_lock);
943 spin_unlock_irq(host->host_lock);
947 static int scsifront_remove(struct xenbus_device *dev)
949 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
951 pr_debug("%s: %s removed\n", __func__, dev->nodename);
953 mutex_lock(&scsifront_mutex);
954 if (info->host_active) {
955 /* Scsi_host not yet removed */
956 scsi_remove_host(info->host);
957 info->host_active = 0;
959 mutex_unlock(&scsifront_mutex);
961 scsifront_free_ring(info);
962 scsi_host_put(info->host);
967 static void scsifront_disconnect(struct vscsifrnt_info *info)
969 struct xenbus_device *dev = info->dev;
970 struct Scsi_Host *host = info->host;
972 pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
975 * When this function is executed, all devices of
976 * Frontend have been deleted.
977 * Therefore, it need not block I/O before remove_host.
980 mutex_lock(&scsifront_mutex);
981 if (info->host_active) {
982 scsi_remove_host(host);
983 info->host_active = 0;
985 mutex_unlock(&scsifront_mutex);
987 xenbus_frontend_closed(dev);
990 static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
992 struct xenbus_device *dev = info->dev;
996 unsigned int dir_n = 0;
997 unsigned int device_state;
998 unsigned int hst, chn, tgt, lun;
999 struct scsi_device *sdev;
1001 dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
1005 /* mark current task as the one allowed to modify device states */
1007 info->curr = current;
1009 for (i = 0; i < dir_n; i++) {
1011 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
1012 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
1014 if (XENBUS_EXIST_ERR(err))
1017 /* virtual SCSI device */
1018 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
1019 err = xenbus_scanf(XBT_NIL, dev->otherend, str,
1020 "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
1021 if (XENBUS_EXIST_ERR(err))
1025 * Front device state path, used in slave_configure called
1026 * on successfull scsi_add_device, and in slave_destroy called
1027 * on remove of a device.
1029 snprintf(info->dev_state_path, sizeof(info->dev_state_path),
1030 "vscsi-devs/%s/state", dir[i]);
1033 case VSCSIFRONT_OP_ADD_LUN:
1034 if (device_state != XenbusStateInitialised)
1037 if (scsi_add_device(info->host, chn, tgt, lun)) {
1038 dev_err(&dev->dev, "scsi_add_device\n");
1039 err = xenbus_printf(XBT_NIL, dev->nodename,
1040 info->dev_state_path,
1041 "%d", XenbusStateClosed);
1043 xenbus_dev_error(dev, err,
1044 "%s: writing dev_state_path", __func__);
1047 case VSCSIFRONT_OP_DEL_LUN:
1048 if (device_state != XenbusStateClosing)
1051 sdev = scsi_device_lookup(info->host, chn, tgt, lun);
1053 scsi_remove_device(sdev);
1054 scsi_device_put(sdev);
1057 case VSCSIFRONT_OP_READD_LUN:
1058 if (device_state == XenbusStateConnected) {
1059 err = xenbus_printf(XBT_NIL, dev->nodename,
1060 info->dev_state_path,
1061 "%d", XenbusStateConnected);
1063 xenbus_dev_error(dev, err,
1064 "%s: writing dev_state_path", __func__);
1077 static void scsifront_read_backend_params(struct xenbus_device *dev,
1078 struct vscsifrnt_info *info)
1080 unsigned int sg_grant, nr_segs;
1082 struct Scsi_Host *host = info->host;
1084 ret = xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg-grant", "%u",
1088 nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
1089 nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
1090 nr_segs = min_t(unsigned int, nr_segs,
1091 VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
1092 sizeof(struct scsiif_request_segment));
1094 if (!info->pause && sg_grant)
1095 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);
1096 else if (info->pause && nr_segs < host->sg_tablesize)
1098 "SG entries decreased from %d to %u - device may not work properly anymore\n",
1099 host->sg_tablesize, nr_segs);
1101 host->sg_tablesize = nr_segs;
1102 host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;
1105 static void scsifront_backend_changed(struct xenbus_device *dev,
1106 enum xenbus_state backend_state)
1108 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1110 pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
1112 switch (backend_state) {
1113 case XenbusStateUnknown:
1114 case XenbusStateInitialising:
1115 case XenbusStateInitWait:
1116 case XenbusStateInitialised:
1119 case XenbusStateConnected:
1120 scsifront_read_backend_params(dev, info);
1123 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);
1124 xenbus_switch_state(dev, XenbusStateConnected);
1129 if (xenbus_read_driver_state(dev->nodename) ==
1130 XenbusStateInitialised)
1131 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1133 if (dev->state != XenbusStateConnected)
1134 xenbus_switch_state(dev, XenbusStateConnected);
1137 case XenbusStateClosed:
1138 if (dev->state == XenbusStateClosed)
1140 /* Missed the backend's Closing state -- fallthrough */
1141 case XenbusStateClosing:
1142 scsifront_disconnect(info);
1145 case XenbusStateReconfiguring:
1146 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
1147 xenbus_switch_state(dev, XenbusStateReconfiguring);
1150 case XenbusStateReconfigured:
1151 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1152 xenbus_switch_state(dev, XenbusStateConnected);
1157 static const struct xenbus_device_id scsifront_ids[] = {
1162 static struct xenbus_driver scsifront_driver = {
1163 .ids = scsifront_ids,
1164 .probe = scsifront_probe,
1165 .remove = scsifront_remove,
1166 .resume = scsifront_resume,
1167 .suspend = scsifront_suspend,
1168 .otherend_changed = scsifront_backend_changed,
1171 static int __init scsifront_init(void)
1176 return xenbus_register_frontend(&scsifront_driver);
1178 module_init(scsifront_init);
1180 static void __exit scsifront_exit(void)
1182 xenbus_unregister_driver(&scsifront_driver);
1184 module_exit(scsifront_exit);
1186 MODULE_DESCRIPTION("Xen SCSI frontend driver");
1187 MODULE_LICENSE("GPL");
1188 MODULE_ALIAS("xen:vscsi");
1189 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");