Version:  2.0.40 2.2.26 2.4.37 2.6.39 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15

Linux/drivers/scsi/virtio_scsi.c

  1 /*
  2  * Virtio SCSI HBA driver
  3  *
  4  * Copyright IBM Corp. 2010
  5  * Copyright Red Hat, Inc. 2011
  6  *
  7  * Authors:
  8  *  Stefan Hajnoczi   <stefanha@linux.vnet.ibm.com>
  9  *  Paolo Bonzini   <pbonzini@redhat.com>
 10  *
 11  * This work is licensed under the terms of the GNU GPL, version 2 or later.
 12  * See the COPYING file in the top-level directory.
 13  *
 14  */
 15 
 16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 17 
 18 #include <linux/module.h>
 19 #include <linux/slab.h>
 20 #include <linux/mempool.h>
 21 #include <linux/virtio.h>
 22 #include <linux/virtio_ids.h>
 23 #include <linux/virtio_config.h>
 24 #include <linux/virtio_scsi.h>
 25 #include <linux/cpu.h>
 26 #include <scsi/scsi_host.h>
 27 #include <scsi/scsi_device.h>
 28 #include <scsi/scsi_cmnd.h>
 29 
 30 #define VIRTIO_SCSI_MEMPOOL_SZ 64
 31 #define VIRTIO_SCSI_EVENT_LEN 8
 32 #define VIRTIO_SCSI_VQ_BASE 2
 33 
 34 /* Command queue element */
 35 struct virtio_scsi_cmd {
 36         struct scsi_cmnd *sc;
 37         struct completion *comp;
 38         union {
 39                 struct virtio_scsi_cmd_req       cmd;
 40                 struct virtio_scsi_ctrl_tmf_req  tmf;
 41                 struct virtio_scsi_ctrl_an_req   an;
 42         } req;
 43         union {
 44                 struct virtio_scsi_cmd_resp      cmd;
 45                 struct virtio_scsi_ctrl_tmf_resp tmf;
 46                 struct virtio_scsi_ctrl_an_resp  an;
 47                 struct virtio_scsi_event         evt;
 48         } resp;
 49 } ____cacheline_aligned_in_smp;
 50 
 51 struct virtio_scsi_event_node {
 52         struct virtio_scsi *vscsi;
 53         struct virtio_scsi_event event;
 54         struct work_struct work;
 55 };
 56 
 57 struct virtio_scsi_vq {
 58         /* Protects vq */
 59         spinlock_t vq_lock;
 60 
 61         struct virtqueue *vq;
 62 };
 63 
 64 /*
 65  * Per-target queue state.
 66  *
 67  * This struct holds the data needed by the queue steering policy.  When a
 68  * target is sent multiple requests, we need to drive them to the same queue so
 69  * that FIFO processing order is kept.  However, if a target was idle, we can
 70  * choose a queue arbitrarily.  In this case the queue is chosen according to
 71  * the current VCPU, so the driver expects the number of request queues to be
 72  * equal to the number of VCPUs.  This makes it easy and fast to select the
 73  * queue, and also lets the driver optimize the IRQ affinity for the virtqueues
 74  * (each virtqueue's affinity is set to the CPU that "owns" the queue).
 75  *
 76  * An interesting effect of this policy is that only writes to req_vq need to
 77  * take the tgt_lock.  Read can be done outside the lock because:
 78  *
 79  * - writes of req_vq only occur when atomic_inc_return(&tgt->reqs) returns 1.
 80  *   In that case, no other CPU is reading req_vq: even if they were in
 81  *   virtscsi_queuecommand_multi, they would be spinning on tgt_lock.
 82  *
 83  * - reads of req_vq only occur when the target is not idle (reqs != 0).
 84  *   A CPU that enters virtscsi_queuecommand_multi will not modify req_vq.
 85  *
 86  * Similarly, decrements of reqs are never concurrent with writes of req_vq.
 87  * Thus they can happen outside the tgt_lock, provided of course we make reqs
 88  * an atomic_t.
 89  */
 90 struct virtio_scsi_target_state {
 91         /* This spinlock never held at the same time as vq_lock. */
 92         spinlock_t tgt_lock;
 93 
 94         /* Count of outstanding requests. */
 95         atomic_t reqs;
 96 
 97         /* Currently active virtqueue for requests sent to this target. */
 98         struct virtio_scsi_vq *req_vq;
 99 };
100 
101 /* Driver instance state */
102 struct virtio_scsi {
103         struct virtio_device *vdev;
104 
105         /* Get some buffers ready for event vq */
106         struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN];
107 
108         u32 num_queues;
109 
110         /* If the affinity hint is set for virtqueues */
111         bool affinity_hint_set;
112 
113         /* CPU hotplug notifier */
114         struct notifier_block nb;
115 
116         struct virtio_scsi_vq ctrl_vq;
117         struct virtio_scsi_vq event_vq;
118         struct virtio_scsi_vq req_vqs[];
119 };
120 
121 static struct kmem_cache *virtscsi_cmd_cache;
122 static mempool_t *virtscsi_cmd_pool;
123 
124 static inline struct Scsi_Host *virtio_scsi_host(struct virtio_device *vdev)
125 {
126         return vdev->priv;
127 }
128 
129 static void virtscsi_compute_resid(struct scsi_cmnd *sc, u32 resid)
130 {
131         if (!resid)
132                 return;
133 
134         if (!scsi_bidi_cmnd(sc)) {
135                 scsi_set_resid(sc, resid);
136                 return;
137         }
138 
139         scsi_in(sc)->resid = min(resid, scsi_in(sc)->length);
140         scsi_out(sc)->resid = resid - scsi_in(sc)->resid;
141 }
142 
143 /**
144  * virtscsi_complete_cmd - finish a scsi_cmd and invoke scsi_done
145  *
146  * Called with vq_lock held.
147  */
148 static void virtscsi_complete_cmd(struct virtio_scsi *vscsi, void *buf)
149 {
150         struct virtio_scsi_cmd *cmd = buf;
151         struct scsi_cmnd *sc = cmd->sc;
152         struct virtio_scsi_cmd_resp *resp = &cmd->resp.cmd;
153         struct virtio_scsi_target_state *tgt =
154                                 scsi_target(sc->device)->hostdata;
155 
156         dev_dbg(&sc->device->sdev_gendev,
157                 "cmd %p response %u status %#02x sense_len %u\n",
158                 sc, resp->response, resp->status, resp->sense_len);
159 
160         sc->result = resp->status;
161         virtscsi_compute_resid(sc, resp->resid);
162         switch (resp->response) {
163         case VIRTIO_SCSI_S_OK:
164                 set_host_byte(sc, DID_OK);
165                 break;
166         case VIRTIO_SCSI_S_OVERRUN:
167                 set_host_byte(sc, DID_ERROR);
168                 break;
169         case VIRTIO_SCSI_S_ABORTED:
170                 set_host_byte(sc, DID_ABORT);
171                 break;
172         case VIRTIO_SCSI_S_BAD_TARGET:
173                 set_host_byte(sc, DID_BAD_TARGET);
174                 break;
175         case VIRTIO_SCSI_S_RESET:
176                 set_host_byte(sc, DID_RESET);
177                 break;
178         case VIRTIO_SCSI_S_BUSY:
179                 set_host_byte(sc, DID_BUS_BUSY);
180                 break;
181         case VIRTIO_SCSI_S_TRANSPORT_FAILURE:
182                 set_host_byte(sc, DID_TRANSPORT_DISRUPTED);
183                 break;
184         case VIRTIO_SCSI_S_TARGET_FAILURE:
185                 set_host_byte(sc, DID_TARGET_FAILURE);
186                 break;
187         case VIRTIO_SCSI_S_NEXUS_FAILURE:
188                 set_host_byte(sc, DID_NEXUS_FAILURE);
189                 break;
190         default:
191                 scmd_printk(KERN_WARNING, sc, "Unknown response %d",
192                             resp->response);
193                 /* fall through */
194         case VIRTIO_SCSI_S_FAILURE:
195                 set_host_byte(sc, DID_ERROR);
196                 break;
197         }
198 
199         WARN_ON(resp->sense_len > VIRTIO_SCSI_SENSE_SIZE);
200         if (sc->sense_buffer) {
201                 memcpy(sc->sense_buffer, resp->sense,
202                        min_t(u32, resp->sense_len, VIRTIO_SCSI_SENSE_SIZE));
203                 if (resp->sense_len)
204                         set_driver_byte(sc, DRIVER_SENSE);
205         }
206 
207         mempool_free(cmd, virtscsi_cmd_pool);
208         sc->scsi_done(sc);
209 
210         atomic_dec(&tgt->reqs);
211 }
212 
213 static void virtscsi_vq_done(struct virtio_scsi *vscsi,
214                              struct virtio_scsi_vq *virtscsi_vq,
215                              void (*fn)(struct virtio_scsi *vscsi, void *buf))
216 {
217         void *buf;
218         unsigned int len;
219         unsigned long flags;
220         struct virtqueue *vq = virtscsi_vq->vq;
221 
222         spin_lock_irqsave(&virtscsi_vq->vq_lock, flags);
223         do {
224                 virtqueue_disable_cb(vq);
225                 while ((buf = virtqueue_get_buf(vq, &len)) != NULL)
226                         fn(vscsi, buf);
227 
228                 if (unlikely(virtqueue_is_broken(vq)))
229                         break;
230         } while (!virtqueue_enable_cb(vq));
231         spin_unlock_irqrestore(&virtscsi_vq->vq_lock, flags);
232 }
233 
234 static void virtscsi_req_done(struct virtqueue *vq)
235 {
236         struct Scsi_Host *sh = virtio_scsi_host(vq->vdev);
237         struct virtio_scsi *vscsi = shost_priv(sh);
238         int index = vq->index - VIRTIO_SCSI_VQ_BASE;
239         struct virtio_scsi_vq *req_vq = &vscsi->req_vqs[index];
240 
241         /*
242          * Read req_vq before decrementing the reqs field in
243          * virtscsi_complete_cmd.
244          *
245          * With barriers:
246          *
247          *      CPU #0                  virtscsi_queuecommand_multi (CPU #1)
248          *      ------------------------------------------------------------
249          *      lock vq_lock
250          *      read req_vq
251          *      read reqs (reqs = 1)
252          *      write reqs (reqs = 0)
253          *                              increment reqs (reqs = 1)
254          *                              write req_vq
255          *
256          * Possible reordering without barriers:
257          *
258          *      CPU #0                  virtscsi_queuecommand_multi (CPU #1)
259          *      ------------------------------------------------------------
260          *      lock vq_lock
261          *      read reqs (reqs = 1)
262          *      write reqs (reqs = 0)
263          *                              increment reqs (reqs = 1)
264          *                              write req_vq
265          *      read (wrong) req_vq
266          *
267          * We do not need a full smp_rmb, because req_vq is required to get
268          * to tgt->reqs: tgt is &vscsi->tgt[sc->device->id], where sc is stored
269          * in the virtqueue as the user token.
270          */
271         smp_read_barrier_depends();
272 
273         virtscsi_vq_done(vscsi, req_vq, virtscsi_complete_cmd);
274 };
275 
276 static void virtscsi_complete_free(struct virtio_scsi *vscsi, void *buf)
277 {
278         struct virtio_scsi_cmd *cmd = buf;
279 
280         if (cmd->comp)
281                 complete_all(cmd->comp);
282         else
283                 mempool_free(cmd, virtscsi_cmd_pool);
284 }
285 
286 static void virtscsi_ctrl_done(struct virtqueue *vq)
287 {
288         struct Scsi_Host *sh = virtio_scsi_host(vq->vdev);
289         struct virtio_scsi *vscsi = shost_priv(sh);
290 
291         virtscsi_vq_done(vscsi, &vscsi->ctrl_vq, virtscsi_complete_free);
292 };
293 
294 static int virtscsi_kick_event(struct virtio_scsi *vscsi,
295                                struct virtio_scsi_event_node *event_node)
296 {
297         int err;
298         struct scatterlist sg;
299         unsigned long flags;
300 
301         sg_init_one(&sg, &event_node->event, sizeof(struct virtio_scsi_event));
302 
303         spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags);
304 
305         err = virtqueue_add_inbuf(vscsi->event_vq.vq, &sg, 1, event_node,
306                                   GFP_ATOMIC);
307         if (!err)
308                 virtqueue_kick(vscsi->event_vq.vq);
309 
310         spin_unlock_irqrestore(&vscsi->event_vq.vq_lock, flags);
311 
312         return err;
313 }
314 
315 static int virtscsi_kick_event_all(struct virtio_scsi *vscsi)
316 {
317         int i;
318 
319         for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++) {
320                 vscsi->event_list[i].vscsi = vscsi;
321                 virtscsi_kick_event(vscsi, &vscsi->event_list[i]);
322         }
323 
324         return 0;
325 }
326 
327 static void virtscsi_cancel_event_work(struct virtio_scsi *vscsi)
328 {
329         int i;
330 
331         for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++)
332                 cancel_work_sync(&vscsi->event_list[i].work);
333 }
334 
335 static void virtscsi_handle_transport_reset(struct virtio_scsi *vscsi,
336                                             struct virtio_scsi_event *event)
337 {
338         struct scsi_device *sdev;
339         struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
340         unsigned int target = event->lun[1];
341         unsigned int lun = (event->lun[2] << 8) | event->lun[3];
342 
343         switch (event->reason) {
344         case VIRTIO_SCSI_EVT_RESET_RESCAN:
345                 scsi_add_device(shost, 0, target, lun);
346                 break;
347         case VIRTIO_SCSI_EVT_RESET_REMOVED:
348                 sdev = scsi_device_lookup(shost, 0, target, lun);
349                 if (sdev) {
350                         scsi_remove_device(sdev);
351                         scsi_device_put(sdev);
352                 } else {
353                         pr_err("SCSI device %d 0 %d %d not found\n",
354                                 shost->host_no, target, lun);
355                 }
356                 break;
357         default:
358                 pr_info("Unsupport virtio scsi event reason %x\n", event->reason);
359         }
360 }
361 
362 static void virtscsi_handle_param_change(struct virtio_scsi *vscsi,
363                                          struct virtio_scsi_event *event)
364 {
365         struct scsi_device *sdev;
366         struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
367         unsigned int target = event->lun[1];
368         unsigned int lun = (event->lun[2] << 8) | event->lun[3];
369         u8 asc = event->reason & 255;
370         u8 ascq = event->reason >> 8;
371 
372         sdev = scsi_device_lookup(shost, 0, target, lun);
373         if (!sdev) {
374                 pr_err("SCSI device %d 0 %d %d not found\n",
375                         shost->host_no, target, lun);
376                 return;
377         }
378 
379         /* Handle "Parameters changed", "Mode parameters changed", and
380            "Capacity data has changed".  */
381         if (asc == 0x2a && (ascq == 0x00 || ascq == 0x01 || ascq == 0x09))
382                 scsi_rescan_device(&sdev->sdev_gendev);
383 
384         scsi_device_put(sdev);
385 }
386 
387 static void virtscsi_handle_event(struct work_struct *work)
388 {
389         struct virtio_scsi_event_node *event_node =
390                 container_of(work, struct virtio_scsi_event_node, work);
391         struct virtio_scsi *vscsi = event_node->vscsi;
392         struct virtio_scsi_event *event = &event_node->event;
393 
394         if (event->event & VIRTIO_SCSI_T_EVENTS_MISSED) {
395                 event->event &= ~VIRTIO_SCSI_T_EVENTS_MISSED;
396                 scsi_scan_host(virtio_scsi_host(vscsi->vdev));
397         }
398 
399         switch (event->event) {
400         case VIRTIO_SCSI_T_NO_EVENT:
401                 break;
402         case VIRTIO_SCSI_T_TRANSPORT_RESET:
403                 virtscsi_handle_transport_reset(vscsi, event);
404                 break;
405         case VIRTIO_SCSI_T_PARAM_CHANGE:
406                 virtscsi_handle_param_change(vscsi, event);
407                 break;
408         default:
409                 pr_err("Unsupport virtio scsi event %x\n", event->event);
410         }
411         virtscsi_kick_event(vscsi, event_node);
412 }
413 
414 static void virtscsi_complete_event(struct virtio_scsi *vscsi, void *buf)
415 {
416         struct virtio_scsi_event_node *event_node = buf;
417 
418         INIT_WORK(&event_node->work, virtscsi_handle_event);
419         schedule_work(&event_node->work);
420 }
421 
422 static void virtscsi_event_done(struct virtqueue *vq)
423 {
424         struct Scsi_Host *sh = virtio_scsi_host(vq->vdev);
425         struct virtio_scsi *vscsi = shost_priv(sh);
426 
427         virtscsi_vq_done(vscsi, &vscsi->event_vq, virtscsi_complete_event);
428 };
429 
430 /**
431  * virtscsi_add_cmd - add a virtio_scsi_cmd to a virtqueue
432  * @vq          : the struct virtqueue we're talking about
433  * @cmd         : command structure
434  * @req_size    : size of the request buffer
435  * @resp_size   : size of the response buffer
436  * @gfp : flags to use for memory allocations
437  */
438 static int virtscsi_add_cmd(struct virtqueue *vq,
439                             struct virtio_scsi_cmd *cmd,
440                             size_t req_size, size_t resp_size, gfp_t gfp)
441 {
442         struct scsi_cmnd *sc = cmd->sc;
443         struct scatterlist *sgs[4], req, resp;
444         struct sg_table *out, *in;
445         unsigned out_num = 0, in_num = 0;
446 
447         out = in = NULL;
448 
449         if (sc && sc->sc_data_direction != DMA_NONE) {
450                 if (sc->sc_data_direction != DMA_FROM_DEVICE)
451                         out = &scsi_out(sc)->table;
452                 if (sc->sc_data_direction != DMA_TO_DEVICE)
453                         in = &scsi_in(sc)->table;
454         }
455 
456         /* Request header.  */
457         sg_init_one(&req, &cmd->req, req_size);
458         sgs[out_num++] = &req;
459 
460         /* Data-out buffer.  */
461         if (out)
462                 sgs[out_num++] = out->sgl;
463 
464         /* Response header.  */
465         sg_init_one(&resp, &cmd->resp, resp_size);
466         sgs[out_num + in_num++] = &resp;
467 
468         /* Data-in buffer */
469         if (in)
470                 sgs[out_num + in_num++] = in->sgl;
471 
472         return virtqueue_add_sgs(vq, sgs, out_num, in_num, cmd, gfp);
473 }
474 
475 static int virtscsi_kick_cmd(struct virtio_scsi_vq *vq,
476                              struct virtio_scsi_cmd *cmd,
477                              size_t req_size, size_t resp_size, gfp_t gfp)
478 {
479         unsigned long flags;
480         int err;
481         bool needs_kick = false;
482 
483         spin_lock_irqsave(&vq->vq_lock, flags);
484         err = virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size, gfp);
485         if (!err)
486                 needs_kick = virtqueue_kick_prepare(vq->vq);
487 
488         spin_unlock_irqrestore(&vq->vq_lock, flags);
489 
490         if (needs_kick)
491                 virtqueue_notify(vq->vq);
492         return err;
493 }
494 
495 static int virtscsi_queuecommand(struct virtio_scsi *vscsi,
496                                  struct virtio_scsi_vq *req_vq,
497                                  struct scsi_cmnd *sc)
498 {
499         struct virtio_scsi_cmd *cmd;
500         int ret;
501 
502         struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
503         BUG_ON(scsi_sg_count(sc) > shost->sg_tablesize);
504 
505         /* TODO: check feature bit and fail if unsupported?  */
506         BUG_ON(sc->sc_data_direction == DMA_BIDIRECTIONAL);
507 
508         dev_dbg(&sc->device->sdev_gendev,
509                 "cmd %p CDB: %#02x\n", sc, sc->cmnd[0]);
510 
511         ret = SCSI_MLQUEUE_HOST_BUSY;
512         cmd = mempool_alloc(virtscsi_cmd_pool, GFP_ATOMIC);
513         if (!cmd)
514                 goto out;
515 
516         memset(cmd, 0, sizeof(*cmd));
517         cmd->sc = sc;
518         cmd->req.cmd = (struct virtio_scsi_cmd_req){
519                 .lun[0] = 1,
520                 .lun[1] = sc->device->id,
521                 .lun[2] = (sc->device->lun >> 8) | 0x40,
522                 .lun[3] = sc->device->lun & 0xff,
523                 .tag = (unsigned long)sc,
524                 .task_attr = VIRTIO_SCSI_S_SIMPLE,
525                 .prio = 0,
526                 .crn = 0,
527         };
528 
529         BUG_ON(sc->cmd_len > VIRTIO_SCSI_CDB_SIZE);
530         memcpy(cmd->req.cmd.cdb, sc->cmnd, sc->cmd_len);
531 
532         if (virtscsi_kick_cmd(req_vq, cmd,
533                               sizeof cmd->req.cmd, sizeof cmd->resp.cmd,
534                               GFP_ATOMIC) == 0)
535                 ret = 0;
536         else
537                 mempool_free(cmd, virtscsi_cmd_pool);
538 
539 out:
540         return ret;
541 }
542 
543 static int virtscsi_queuecommand_single(struct Scsi_Host *sh,
544                                         struct scsi_cmnd *sc)
545 {
546         struct virtio_scsi *vscsi = shost_priv(sh);
547         struct virtio_scsi_target_state *tgt =
548                                 scsi_target(sc->device)->hostdata;
549 
550         atomic_inc(&tgt->reqs);
551         return virtscsi_queuecommand(vscsi, &vscsi->req_vqs[0], sc);
552 }
553 
554 static struct virtio_scsi_vq *virtscsi_pick_vq(struct virtio_scsi *vscsi,
555                                                struct virtio_scsi_target_state *tgt)
556 {
557         struct virtio_scsi_vq *vq;
558         unsigned long flags;
559         u32 queue_num;
560 
561         spin_lock_irqsave(&tgt->tgt_lock, flags);
562 
563         /*
564          * The memory barrier after atomic_inc_return matches
565          * the smp_read_barrier_depends() in virtscsi_req_done.
566          */
567         if (atomic_inc_return(&tgt->reqs) > 1)
568                 vq = ACCESS_ONCE(tgt->req_vq);
569         else {
570                 queue_num = smp_processor_id();
571                 while (unlikely(queue_num >= vscsi->num_queues))
572                         queue_num -= vscsi->num_queues;
573 
574                 tgt->req_vq = vq = &vscsi->req_vqs[queue_num];
575         }
576 
577         spin_unlock_irqrestore(&tgt->tgt_lock, flags);
578         return vq;
579 }
580 
581 static int virtscsi_queuecommand_multi(struct Scsi_Host *sh,
582                                        struct scsi_cmnd *sc)
583 {
584         struct virtio_scsi *vscsi = shost_priv(sh);
585         struct virtio_scsi_target_state *tgt =
586                                 scsi_target(sc->device)->hostdata;
587         struct virtio_scsi_vq *req_vq = virtscsi_pick_vq(vscsi, tgt);
588 
589         return virtscsi_queuecommand(vscsi, req_vq, sc);
590 }
591 
592 static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)
593 {
594         DECLARE_COMPLETION_ONSTACK(comp);
595         int ret = FAILED;
596 
597         cmd->comp = &comp;
598         if (virtscsi_kick_cmd(&vscsi->ctrl_vq, cmd,
599                               sizeof cmd->req.tmf, sizeof cmd->resp.tmf,
600                               GFP_NOIO) < 0)
601                 goto out;
602 
603         wait_for_completion(&comp);
604         if (cmd->resp.tmf.response == VIRTIO_SCSI_S_OK ||
605             cmd->resp.tmf.response == VIRTIO_SCSI_S_FUNCTION_SUCCEEDED)
606                 ret = SUCCESS;
607 
608 out:
609         mempool_free(cmd, virtscsi_cmd_pool);
610         return ret;
611 }
612 
613 static int virtscsi_device_reset(struct scsi_cmnd *sc)
614 {
615         struct virtio_scsi *vscsi = shost_priv(sc->device->host);
616         struct virtio_scsi_cmd *cmd;
617 
618         sdev_printk(KERN_INFO, sc->device, "device reset\n");
619         cmd = mempool_alloc(virtscsi_cmd_pool, GFP_NOIO);
620         if (!cmd)
621                 return FAILED;
622 
623         memset(cmd, 0, sizeof(*cmd));
624         cmd->sc = sc;
625         cmd->req.tmf = (struct virtio_scsi_ctrl_tmf_req){
626                 .type = VIRTIO_SCSI_T_TMF,
627                 .subtype = VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET,
628                 .lun[0] = 1,
629                 .lun[1] = sc->device->id,
630                 .lun[2] = (sc->device->lun >> 8) | 0x40,
631                 .lun[3] = sc->device->lun & 0xff,
632         };
633         return virtscsi_tmf(vscsi, cmd);
634 }
635 
636 static int virtscsi_abort(struct scsi_cmnd *sc)
637 {
638         struct virtio_scsi *vscsi = shost_priv(sc->device->host);
639         struct virtio_scsi_cmd *cmd;
640 
641         scmd_printk(KERN_INFO, sc, "abort\n");
642         cmd = mempool_alloc(virtscsi_cmd_pool, GFP_NOIO);
643         if (!cmd)
644                 return FAILED;
645 
646         memset(cmd, 0, sizeof(*cmd));
647         cmd->sc = sc;
648         cmd->req.tmf = (struct virtio_scsi_ctrl_tmf_req){
649                 .type = VIRTIO_SCSI_T_TMF,
650                 .subtype = VIRTIO_SCSI_T_TMF_ABORT_TASK,
651                 .lun[0] = 1,
652                 .lun[1] = sc->device->id,
653                 .lun[2] = (sc->device->lun >> 8) | 0x40,
654                 .lun[3] = sc->device->lun & 0xff,
655                 .tag = (unsigned long)sc,
656         };
657         return virtscsi_tmf(vscsi, cmd);
658 }
659 
660 static int virtscsi_target_alloc(struct scsi_target *starget)
661 {
662         struct virtio_scsi_target_state *tgt =
663                                 kmalloc(sizeof(*tgt), GFP_KERNEL);
664         if (!tgt)
665                 return -ENOMEM;
666 
667         spin_lock_init(&tgt->tgt_lock);
668         atomic_set(&tgt->reqs, 0);
669         tgt->req_vq = NULL;
670 
671         starget->hostdata = tgt;
672         return 0;
673 }
674 
675 static void virtscsi_target_destroy(struct scsi_target *starget)
676 {
677         struct virtio_scsi_target_state *tgt = starget->hostdata;
678         kfree(tgt);
679 }
680 
681 static struct scsi_host_template virtscsi_host_template_single = {
682         .module = THIS_MODULE,
683         .name = "Virtio SCSI HBA",
684         .proc_name = "virtio_scsi",
685         .this_id = -1,
686         .queuecommand = virtscsi_queuecommand_single,
687         .eh_abort_handler = virtscsi_abort,
688         .eh_device_reset_handler = virtscsi_device_reset,
689 
690         .can_queue = 1024,
691         .dma_boundary = UINT_MAX,
692         .use_clustering = ENABLE_CLUSTERING,
693         .target_alloc = virtscsi_target_alloc,
694         .target_destroy = virtscsi_target_destroy,
695 };
696 
697 static struct scsi_host_template virtscsi_host_template_multi = {
698         .module = THIS_MODULE,
699         .name = "Virtio SCSI HBA",
700         .proc_name = "virtio_scsi",
701         .this_id = -1,
702         .queuecommand = virtscsi_queuecommand_multi,
703         .eh_abort_handler = virtscsi_abort,
704         .eh_device_reset_handler = virtscsi_device_reset,
705 
706         .can_queue = 1024,
707         .dma_boundary = UINT_MAX,
708         .use_clustering = ENABLE_CLUSTERING,
709         .target_alloc = virtscsi_target_alloc,
710         .target_destroy = virtscsi_target_destroy,
711 };
712 
713 #define virtscsi_config_get(vdev, fld) \
714         ({ \
715                 typeof(((struct virtio_scsi_config *)0)->fld) __val; \
716                 virtio_cread(vdev, struct virtio_scsi_config, fld, &__val); \
717                 __val; \
718         })
719 
720 #define virtscsi_config_set(vdev, fld, val) \
721         do { \
722                 typeof(((struct virtio_scsi_config *)0)->fld) __val = (val); \
723                 virtio_cwrite(vdev, struct virtio_scsi_config, fld, &__val); \
724         } while(0)
725 
726 static void __virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity)
727 {
728         int i;
729         int cpu;
730 
731         /* In multiqueue mode, when the number of cpu is equal
732          * to the number of request queues, we let the qeueues
733          * to be private to one cpu by setting the affinity hint
734          * to eliminate the contention.
735          */
736         if ((vscsi->num_queues == 1 ||
737              vscsi->num_queues != num_online_cpus()) && affinity) {
738                 if (vscsi->affinity_hint_set)
739                         affinity = false;
740                 else
741                         return;
742         }
743 
744         if (affinity) {
745                 i = 0;
746                 for_each_online_cpu(cpu) {
747                         virtqueue_set_affinity(vscsi->req_vqs[i].vq, cpu);
748                         i++;
749                 }
750 
751                 vscsi->affinity_hint_set = true;
752         } else {
753                 for (i = 0; i < vscsi->num_queues; i++) {
754                         if (!vscsi->req_vqs[i].vq)
755                                 continue;
756 
757                         virtqueue_set_affinity(vscsi->req_vqs[i].vq, -1);
758                 }
759 
760                 vscsi->affinity_hint_set = false;
761         }
762 }
763 
764 static void virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity)
765 {
766         get_online_cpus();
767         __virtscsi_set_affinity(vscsi, affinity);
768         put_online_cpus();
769 }
770 
771 static int virtscsi_cpu_callback(struct notifier_block *nfb,
772                                  unsigned long action, void *hcpu)
773 {
774         struct virtio_scsi *vscsi = container_of(nfb, struct virtio_scsi, nb);
775         switch(action) {
776         case CPU_ONLINE:
777         case CPU_ONLINE_FROZEN:
778         case CPU_DEAD:
779         case CPU_DEAD_FROZEN:
780                 __virtscsi_set_affinity(vscsi, true);
781                 break;
782         default:
783                 break;
784         }
785         return NOTIFY_OK;
786 }
787 
788 static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
789                              struct virtqueue *vq)
790 {
791         spin_lock_init(&virtscsi_vq->vq_lock);
792         virtscsi_vq->vq = vq;
793 }
794 
795 static void virtscsi_scan(struct virtio_device *vdev)
796 {
797         struct Scsi_Host *shost = (struct Scsi_Host *)vdev->priv;
798 
799         scsi_scan_host(shost);
800 }
801 
802 static void virtscsi_remove_vqs(struct virtio_device *vdev)
803 {
804         struct Scsi_Host *sh = virtio_scsi_host(vdev);
805         struct virtio_scsi *vscsi = shost_priv(sh);
806 
807         virtscsi_set_affinity(vscsi, false);
808 
809         /* Stop all the virtqueues. */
810         vdev->config->reset(vdev);
811 
812         vdev->config->del_vqs(vdev);
813 }
814 
815 static int virtscsi_init(struct virtio_device *vdev,
816                          struct virtio_scsi *vscsi)
817 {
818         int err;
819         u32 i;
820         u32 num_vqs;
821         vq_callback_t **callbacks;
822         const char **names;
823         struct virtqueue **vqs;
824 
825         num_vqs = vscsi->num_queues + VIRTIO_SCSI_VQ_BASE;
826         vqs = kmalloc(num_vqs * sizeof(struct virtqueue *), GFP_KERNEL);
827         callbacks = kmalloc(num_vqs * sizeof(vq_callback_t *), GFP_KERNEL);
828         names = kmalloc(num_vqs * sizeof(char *), GFP_KERNEL);
829 
830         if (!callbacks || !vqs || !names) {
831                 err = -ENOMEM;
832                 goto out;
833         }
834 
835         callbacks[0] = virtscsi_ctrl_done;
836         callbacks[1] = virtscsi_event_done;
837         names[0] = "control";
838         names[1] = "event";
839         for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs; i++) {
840                 callbacks[i] = virtscsi_req_done;
841                 names[i] = "request";
842         }
843 
844         /* Discover virtqueues and write information to configuration.  */
845         err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names);
846         if (err)
847                 goto out;
848 
849         virtscsi_init_vq(&vscsi->ctrl_vq, vqs[0]);
850         virtscsi_init_vq(&vscsi->event_vq, vqs[1]);
851         for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs; i++)
852                 virtscsi_init_vq(&vscsi->req_vqs[i - VIRTIO_SCSI_VQ_BASE],
853                                  vqs[i]);
854 
855         virtscsi_set_affinity(vscsi, true);
856 
857         virtscsi_config_set(vdev, cdb_size, VIRTIO_SCSI_CDB_SIZE);
858         virtscsi_config_set(vdev, sense_size, VIRTIO_SCSI_SENSE_SIZE);
859 
860         if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
861                 virtscsi_kick_event_all(vscsi);
862 
863         err = 0;
864 
865 out:
866         kfree(names);
867         kfree(callbacks);
868         kfree(vqs);
869         if (err)
870                 virtscsi_remove_vqs(vdev);
871         return err;
872 }
873 
874 static int virtscsi_probe(struct virtio_device *vdev)
875 {
876         struct Scsi_Host *shost;
877         struct virtio_scsi *vscsi;
878         int err;
879         u32 sg_elems, num_targets;
880         u32 cmd_per_lun;
881         u32 num_queues;
882         struct scsi_host_template *hostt;
883 
884         /* We need to know how many queues before we allocate. */
885         num_queues = virtscsi_config_get(vdev, num_queues) ? : 1;
886 
887         num_targets = virtscsi_config_get(vdev, max_target) + 1;
888 
889         if (num_queues == 1)
890                 hostt = &virtscsi_host_template_single;
891         else
892                 hostt = &virtscsi_host_template_multi;
893 
894         shost = scsi_host_alloc(hostt,
895                 sizeof(*vscsi) + sizeof(vscsi->req_vqs[0]) * num_queues);
896         if (!shost)
897                 return -ENOMEM;
898 
899         sg_elems = virtscsi_config_get(vdev, seg_max) ?: 1;
900         shost->sg_tablesize = sg_elems;
901         vscsi = shost_priv(shost);
902         vscsi->vdev = vdev;
903         vscsi->num_queues = num_queues;
904         vdev->priv = shost;
905 
906         err = virtscsi_init(vdev, vscsi);
907         if (err)
908                 goto virtscsi_init_failed;
909 
910         vscsi->nb.notifier_call = &virtscsi_cpu_callback;
911         err = register_hotcpu_notifier(&vscsi->nb);
912         if (err) {
913                 pr_err("registering cpu notifier failed\n");
914                 goto scsi_add_host_failed;
915         }
916 
917         cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1;
918         shost->cmd_per_lun = min_t(u32, cmd_per_lun, shost->can_queue);
919         shost->max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0xFFFF;
920 
921         /* LUNs > 256 are reported with format 1, so they go in the range
922          * 16640-32767.
923          */
924         shost->max_lun = virtscsi_config_get(vdev, max_lun) + 1 + 0x4000;
925         shost->max_id = num_targets;
926         shost->max_channel = 0;
927         shost->max_cmd_len = VIRTIO_SCSI_CDB_SIZE;
928         err = scsi_add_host(shost, &vdev->dev);
929         if (err)
930                 goto scsi_add_host_failed;
931         /*
932          * scsi_scan_host() happens in virtscsi_scan() via virtio_driver->scan()
933          * after VIRTIO_CONFIG_S_DRIVER_OK has been set..
934          */
935         return 0;
936 
937 scsi_add_host_failed:
938         vdev->config->del_vqs(vdev);
939 virtscsi_init_failed:
940         scsi_host_put(shost);
941         return err;
942 }
943 
944 static void virtscsi_remove(struct virtio_device *vdev)
945 {
946         struct Scsi_Host *shost = virtio_scsi_host(vdev);
947         struct virtio_scsi *vscsi = shost_priv(shost);
948 
949         if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
950                 virtscsi_cancel_event_work(vscsi);
951 
952         scsi_remove_host(shost);
953 
954         unregister_hotcpu_notifier(&vscsi->nb);
955 
956         virtscsi_remove_vqs(vdev);
957         scsi_host_put(shost);
958 }
959 
960 #ifdef CONFIG_PM_SLEEP
961 static int virtscsi_freeze(struct virtio_device *vdev)
962 {
963         struct Scsi_Host *sh = virtio_scsi_host(vdev);
964         struct virtio_scsi *vscsi = shost_priv(sh);
965 
966         unregister_hotcpu_notifier(&vscsi->nb);
967         virtscsi_remove_vqs(vdev);
968         return 0;
969 }
970 
971 static int virtscsi_restore(struct virtio_device *vdev)
972 {
973         struct Scsi_Host *sh = virtio_scsi_host(vdev);
974         struct virtio_scsi *vscsi = shost_priv(sh);
975         int err;
976 
977         err = virtscsi_init(vdev, vscsi);
978         if (err)
979                 return err;
980 
981         err = register_hotcpu_notifier(&vscsi->nb);
982         if (err)
983                 vdev->config->del_vqs(vdev);
984 
985         return err;
986 }
987 #endif
988 
989 static struct virtio_device_id id_table[] = {
990         { VIRTIO_ID_SCSI, VIRTIO_DEV_ANY_ID },
991         { 0 },
992 };
993 
994 static unsigned int features[] = {
995         VIRTIO_SCSI_F_HOTPLUG,
996         VIRTIO_SCSI_F_CHANGE,
997 };
998 
999 static struct virtio_driver virtio_scsi_driver = {
1000         .feature_table = features,
1001         .feature_table_size = ARRAY_SIZE(features),
1002         .driver.name = KBUILD_MODNAME,
1003         .driver.owner = THIS_MODULE,
1004         .id_table = id_table,
1005         .probe = virtscsi_probe,
1006         .scan = virtscsi_scan,
1007 #ifdef CONFIG_PM_SLEEP
1008         .freeze = virtscsi_freeze,
1009         .restore = virtscsi_restore,
1010 #endif
1011         .remove = virtscsi_remove,
1012 };
1013 
1014 static int __init init(void)
1015 {
1016         int ret = -ENOMEM;
1017 
1018         virtscsi_cmd_cache = KMEM_CACHE(virtio_scsi_cmd, 0);
1019         if (!virtscsi_cmd_cache) {
1020                 pr_err("kmem_cache_create() for virtscsi_cmd_cache failed\n");
1021                 goto error;
1022         }
1023 
1024 
1025         virtscsi_cmd_pool =
1026                 mempool_create_slab_pool(VIRTIO_SCSI_MEMPOOL_SZ,
1027                                          virtscsi_cmd_cache);
1028         if (!virtscsi_cmd_pool) {
1029                 pr_err("mempool_create() for virtscsi_cmd_pool failed\n");
1030                 goto error;
1031         }
1032         ret = register_virtio_driver(&virtio_scsi_driver);
1033         if (ret < 0)
1034                 goto error;
1035 
1036         return 0;
1037 
1038 error:
1039         if (virtscsi_cmd_pool) {
1040                 mempool_destroy(virtscsi_cmd_pool);
1041                 virtscsi_cmd_pool = NULL;
1042         }
1043         if (virtscsi_cmd_cache) {
1044                 kmem_cache_destroy(virtscsi_cmd_cache);
1045                 virtscsi_cmd_cache = NULL;
1046         }
1047         return ret;
1048 }
1049 
1050 static void __exit fini(void)
1051 {
1052         unregister_virtio_driver(&virtio_scsi_driver);
1053         mempool_destroy(virtscsi_cmd_pool);
1054         kmem_cache_destroy(virtscsi_cmd_cache);
1055 }
1056 module_init(init);
1057 module_exit(fini);
1058 
1059 MODULE_DEVICE_TABLE(virtio, id_table);
1060 MODULE_DESCRIPTION("Virtio SCSI HBA driver");
1061 MODULE_LICENSE("GPL");
1062 

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