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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 <linux/blkdev.h>
 27 #include <scsi/scsi_host.h>
 28 #include <scsi/scsi_device.h>
 29 #include <scsi/scsi_cmnd.h>
 30 #include <scsi/scsi_tcq.h>
 31 #include <linux/seqlock.h>
 32 
 33 #define VIRTIO_SCSI_MEMPOOL_SZ 64
 34 #define VIRTIO_SCSI_EVENT_LEN 8
 35 #define VIRTIO_SCSI_VQ_BASE 2
 36 
 37 /* Command queue element */
 38 struct virtio_scsi_cmd {
 39         struct scsi_cmnd *sc;
 40         struct completion *comp;
 41         union {
 42                 struct virtio_scsi_cmd_req       cmd;
 43                 struct virtio_scsi_cmd_req_pi    cmd_pi;
 44                 struct virtio_scsi_ctrl_tmf_req  tmf;
 45                 struct virtio_scsi_ctrl_an_req   an;
 46         } req;
 47         union {
 48                 struct virtio_scsi_cmd_resp      cmd;
 49                 struct virtio_scsi_ctrl_tmf_resp tmf;
 50                 struct virtio_scsi_ctrl_an_resp  an;
 51                 struct virtio_scsi_event         evt;
 52         } resp;
 53 } ____cacheline_aligned_in_smp;
 54 
 55 struct virtio_scsi_event_node {
 56         struct virtio_scsi *vscsi;
 57         struct virtio_scsi_event event;
 58         struct work_struct work;
 59 };
 60 
 61 struct virtio_scsi_vq {
 62         /* Protects vq */
 63         spinlock_t vq_lock;
 64 
 65         struct virtqueue *vq;
 66 };
 67 
 68 /*
 69  * Per-target queue state.
 70  *
 71  * This struct holds the data needed by the queue steering policy.  When a
 72  * target is sent multiple requests, we need to drive them to the same queue so
 73  * that FIFO processing order is kept.  However, if a target was idle, we can
 74  * choose a queue arbitrarily.  In this case the queue is chosen according to
 75  * the current VCPU, so the driver expects the number of request queues to be
 76  * equal to the number of VCPUs.  This makes it easy and fast to select the
 77  * queue, and also lets the driver optimize the IRQ affinity for the virtqueues
 78  * (each virtqueue's affinity is set to the CPU that "owns" the queue).
 79  *
 80  * tgt_seq is held to serialize reading and writing req_vq.
 81  *
 82  * Decrements of reqs are never concurrent with writes of req_vq: before the
 83  * decrement reqs will be != 0; after the decrement the virtqueue completion
 84  * routine will not use the req_vq so it can be changed by a new request.
 85  * Thus they can happen outside the tgt_seq, provided of course we make reqs
 86  * an atomic_t.
 87  */
 88 struct virtio_scsi_target_state {
 89         seqcount_t tgt_seq;
 90 
 91         /* Count of outstanding requests. */
 92         atomic_t reqs;
 93 
 94         /* Currently active virtqueue for requests sent to this target. */
 95         struct virtio_scsi_vq *req_vq;
 96 };
 97 
 98 /* Driver instance state */
 99 struct virtio_scsi {
100         struct virtio_device *vdev;
101 
102         /* Get some buffers ready for event vq */
103         struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN];
104 
105         u32 num_queues;
106 
107         /* If the affinity hint is set for virtqueues */
108         bool affinity_hint_set;
109 
110         struct hlist_node node;
111         struct hlist_node node_dead;
112 
113         /* Protected by event_vq lock */
114         bool stop_events;
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 enum cpuhp_state virtioscsi_online;
122 static struct kmem_cache *virtscsi_cmd_cache;
123 static mempool_t *virtscsi_cmd_pool;
124 
125 static inline struct Scsi_Host *virtio_scsi_host(struct virtio_device *vdev)
126 {
127         return vdev->priv;
128 }
129 
130 static void virtscsi_compute_resid(struct scsi_cmnd *sc, u32 resid)
131 {
132         if (!resid)
133                 return;
134 
135         if (!scsi_bidi_cmnd(sc)) {
136                 scsi_set_resid(sc, resid);
137                 return;
138         }
139 
140         scsi_in(sc)->resid = min(resid, scsi_in(sc)->length);
141         scsi_out(sc)->resid = resid - scsi_in(sc)->resid;
142 }
143 
144 /**
145  * virtscsi_complete_cmd - finish a scsi_cmd and invoke scsi_done
146  *
147  * Called with vq_lock held.
148  */
149 static void virtscsi_complete_cmd(struct virtio_scsi *vscsi, void *buf)
150 {
151         struct virtio_scsi_cmd *cmd = buf;
152         struct scsi_cmnd *sc = cmd->sc;
153         struct virtio_scsi_cmd_resp *resp = &cmd->resp.cmd;
154         struct virtio_scsi_target_state *tgt =
155                                 scsi_target(sc->device)->hostdata;
156 
157         dev_dbg(&sc->device->sdev_gendev,
158                 "cmd %p response %u status %#02x sense_len %u\n",
159                 sc, resp->response, resp->status, resp->sense_len);
160 
161         sc->result = resp->status;
162         virtscsi_compute_resid(sc, virtio32_to_cpu(vscsi->vdev, resp->resid));
163         switch (resp->response) {
164         case VIRTIO_SCSI_S_OK:
165                 set_host_byte(sc, DID_OK);
166                 break;
167         case VIRTIO_SCSI_S_OVERRUN:
168                 set_host_byte(sc, DID_ERROR);
169                 break;
170         case VIRTIO_SCSI_S_ABORTED:
171                 set_host_byte(sc, DID_ABORT);
172                 break;
173         case VIRTIO_SCSI_S_BAD_TARGET:
174                 set_host_byte(sc, DID_BAD_TARGET);
175                 break;
176         case VIRTIO_SCSI_S_RESET:
177                 set_host_byte(sc, DID_RESET);
178                 break;
179         case VIRTIO_SCSI_S_BUSY:
180                 set_host_byte(sc, DID_BUS_BUSY);
181                 break;
182         case VIRTIO_SCSI_S_TRANSPORT_FAILURE:
183                 set_host_byte(sc, DID_TRANSPORT_DISRUPTED);
184                 break;
185         case VIRTIO_SCSI_S_TARGET_FAILURE:
186                 set_host_byte(sc, DID_TARGET_FAILURE);
187                 break;
188         case VIRTIO_SCSI_S_NEXUS_FAILURE:
189                 set_host_byte(sc, DID_NEXUS_FAILURE);
190                 break;
191         default:
192                 scmd_printk(KERN_WARNING, sc, "Unknown response %d",
193                             resp->response);
194                 /* fall through */
195         case VIRTIO_SCSI_S_FAILURE:
196                 set_host_byte(sc, DID_ERROR);
197                 break;
198         }
199 
200         WARN_ON(virtio32_to_cpu(vscsi->vdev, resp->sense_len) >
201                 VIRTIO_SCSI_SENSE_SIZE);
202         if (sc->sense_buffer) {
203                 memcpy(sc->sense_buffer, resp->sense,
204                        min_t(u32,
205                              virtio32_to_cpu(vscsi->vdev, resp->sense_len),
206                              VIRTIO_SCSI_SENSE_SIZE));
207                 if (resp->sense_len)
208                         set_driver_byte(sc, DRIVER_SENSE);
209         }
210 
211         sc->scsi_done(sc);
212 
213         atomic_dec(&tgt->reqs);
214 }
215 
216 static void virtscsi_vq_done(struct virtio_scsi *vscsi,
217                              struct virtio_scsi_vq *virtscsi_vq,
218                              void (*fn)(struct virtio_scsi *vscsi, void *buf))
219 {
220         void *buf;
221         unsigned int len;
222         unsigned long flags;
223         struct virtqueue *vq = virtscsi_vq->vq;
224 
225         spin_lock_irqsave(&virtscsi_vq->vq_lock, flags);
226         do {
227                 virtqueue_disable_cb(vq);
228                 while ((buf = virtqueue_get_buf(vq, &len)) != NULL)
229                         fn(vscsi, buf);
230 
231                 if (unlikely(virtqueue_is_broken(vq)))
232                         break;
233         } while (!virtqueue_enable_cb(vq));
234         spin_unlock_irqrestore(&virtscsi_vq->vq_lock, flags);
235 }
236 
237 static void virtscsi_req_done(struct virtqueue *vq)
238 {
239         struct Scsi_Host *sh = virtio_scsi_host(vq->vdev);
240         struct virtio_scsi *vscsi = shost_priv(sh);
241         int index = vq->index - VIRTIO_SCSI_VQ_BASE;
242         struct virtio_scsi_vq *req_vq = &vscsi->req_vqs[index];
243 
244         virtscsi_vq_done(vscsi, req_vq, virtscsi_complete_cmd);
245 };
246 
247 static void virtscsi_poll_requests(struct virtio_scsi *vscsi)
248 {
249         int i, num_vqs;
250 
251         num_vqs = vscsi->num_queues;
252         for (i = 0; i < num_vqs; i++)
253                 virtscsi_vq_done(vscsi, &vscsi->req_vqs[i],
254                                  virtscsi_complete_cmd);
255 }
256 
257 static void virtscsi_complete_free(struct virtio_scsi *vscsi, void *buf)
258 {
259         struct virtio_scsi_cmd *cmd = buf;
260 
261         if (cmd->comp)
262                 complete(cmd->comp);
263 }
264 
265 static void virtscsi_ctrl_done(struct virtqueue *vq)
266 {
267         struct Scsi_Host *sh = virtio_scsi_host(vq->vdev);
268         struct virtio_scsi *vscsi = shost_priv(sh);
269 
270         virtscsi_vq_done(vscsi, &vscsi->ctrl_vq, virtscsi_complete_free);
271 };
272 
273 static void virtscsi_handle_event(struct work_struct *work);
274 
275 static int virtscsi_kick_event(struct virtio_scsi *vscsi,
276                                struct virtio_scsi_event_node *event_node)
277 {
278         int err;
279         struct scatterlist sg;
280         unsigned long flags;
281 
282         INIT_WORK(&event_node->work, virtscsi_handle_event);
283         sg_init_one(&sg, &event_node->event, sizeof(struct virtio_scsi_event));
284 
285         spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags);
286 
287         err = virtqueue_add_inbuf(vscsi->event_vq.vq, &sg, 1, event_node,
288                                   GFP_ATOMIC);
289         if (!err)
290                 virtqueue_kick(vscsi->event_vq.vq);
291 
292         spin_unlock_irqrestore(&vscsi->event_vq.vq_lock, flags);
293 
294         return err;
295 }
296 
297 static int virtscsi_kick_event_all(struct virtio_scsi *vscsi)
298 {
299         int i;
300 
301         for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++) {
302                 vscsi->event_list[i].vscsi = vscsi;
303                 virtscsi_kick_event(vscsi, &vscsi->event_list[i]);
304         }
305 
306         return 0;
307 }
308 
309 static void virtscsi_cancel_event_work(struct virtio_scsi *vscsi)
310 {
311         int i;
312 
313         /* Stop scheduling work before calling cancel_work_sync.  */
314         spin_lock_irq(&vscsi->event_vq.vq_lock);
315         vscsi->stop_events = true;
316         spin_unlock_irq(&vscsi->event_vq.vq_lock);
317 
318         for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++)
319                 cancel_work_sync(&vscsi->event_list[i].work);
320 }
321 
322 static void virtscsi_handle_transport_reset(struct virtio_scsi *vscsi,
323                                             struct virtio_scsi_event *event)
324 {
325         struct scsi_device *sdev;
326         struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
327         unsigned int target = event->lun[1];
328         unsigned int lun = (event->lun[2] << 8) | event->lun[3];
329 
330         switch (virtio32_to_cpu(vscsi->vdev, event->reason)) {
331         case VIRTIO_SCSI_EVT_RESET_RESCAN:
332                 scsi_add_device(shost, 0, target, lun);
333                 break;
334         case VIRTIO_SCSI_EVT_RESET_REMOVED:
335                 sdev = scsi_device_lookup(shost, 0, target, lun);
336                 if (sdev) {
337                         scsi_remove_device(sdev);
338                         scsi_device_put(sdev);
339                 } else {
340                         pr_err("SCSI device %d 0 %d %d not found\n",
341                                 shost->host_no, target, lun);
342                 }
343                 break;
344         default:
345                 pr_info("Unsupport virtio scsi event reason %x\n", event->reason);
346         }
347 }
348 
349 static void virtscsi_handle_param_change(struct virtio_scsi *vscsi,
350                                          struct virtio_scsi_event *event)
351 {
352         struct scsi_device *sdev;
353         struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
354         unsigned int target = event->lun[1];
355         unsigned int lun = (event->lun[2] << 8) | event->lun[3];
356         u8 asc = virtio32_to_cpu(vscsi->vdev, event->reason) & 255;
357         u8 ascq = virtio32_to_cpu(vscsi->vdev, event->reason) >> 8;
358 
359         sdev = scsi_device_lookup(shost, 0, target, lun);
360         if (!sdev) {
361                 pr_err("SCSI device %d 0 %d %d not found\n",
362                         shost->host_no, target, lun);
363                 return;
364         }
365 
366         /* Handle "Parameters changed", "Mode parameters changed", and
367            "Capacity data has changed".  */
368         if (asc == 0x2a && (ascq == 0x00 || ascq == 0x01 || ascq == 0x09))
369                 scsi_rescan_device(&sdev->sdev_gendev);
370 
371         scsi_device_put(sdev);
372 }
373 
374 static void virtscsi_handle_event(struct work_struct *work)
375 {
376         struct virtio_scsi_event_node *event_node =
377                 container_of(work, struct virtio_scsi_event_node, work);
378         struct virtio_scsi *vscsi = event_node->vscsi;
379         struct virtio_scsi_event *event = &event_node->event;
380 
381         if (event->event &
382             cpu_to_virtio32(vscsi->vdev, VIRTIO_SCSI_T_EVENTS_MISSED)) {
383                 event->event &= ~cpu_to_virtio32(vscsi->vdev,
384                                                    VIRTIO_SCSI_T_EVENTS_MISSED);
385                 scsi_scan_host(virtio_scsi_host(vscsi->vdev));
386         }
387 
388         switch (virtio32_to_cpu(vscsi->vdev, event->event)) {
389         case VIRTIO_SCSI_T_NO_EVENT:
390                 break;
391         case VIRTIO_SCSI_T_TRANSPORT_RESET:
392                 virtscsi_handle_transport_reset(vscsi, event);
393                 break;
394         case VIRTIO_SCSI_T_PARAM_CHANGE:
395                 virtscsi_handle_param_change(vscsi, event);
396                 break;
397         default:
398                 pr_err("Unsupport virtio scsi event %x\n", event->event);
399         }
400         virtscsi_kick_event(vscsi, event_node);
401 }
402 
403 static void virtscsi_complete_event(struct virtio_scsi *vscsi, void *buf)
404 {
405         struct virtio_scsi_event_node *event_node = buf;
406 
407         if (!vscsi->stop_events)
408                 queue_work(system_freezable_wq, &event_node->work);
409 }
410 
411 static void virtscsi_event_done(struct virtqueue *vq)
412 {
413         struct Scsi_Host *sh = virtio_scsi_host(vq->vdev);
414         struct virtio_scsi *vscsi = shost_priv(sh);
415 
416         virtscsi_vq_done(vscsi, &vscsi->event_vq, virtscsi_complete_event);
417 };
418 
419 /**
420  * virtscsi_add_cmd - add a virtio_scsi_cmd to a virtqueue
421  * @vq          : the struct virtqueue we're talking about
422  * @cmd         : command structure
423  * @req_size    : size of the request buffer
424  * @resp_size   : size of the response buffer
425  */
426 static int virtscsi_add_cmd(struct virtqueue *vq,
427                             struct virtio_scsi_cmd *cmd,
428                             size_t req_size, size_t resp_size)
429 {
430         struct scsi_cmnd *sc = cmd->sc;
431         struct scatterlist *sgs[6], req, resp;
432         struct sg_table *out, *in;
433         unsigned out_num = 0, in_num = 0;
434 
435         out = in = NULL;
436 
437         if (sc && sc->sc_data_direction != DMA_NONE) {
438                 if (sc->sc_data_direction != DMA_FROM_DEVICE)
439                         out = &scsi_out(sc)->table;
440                 if (sc->sc_data_direction != DMA_TO_DEVICE)
441                         in = &scsi_in(sc)->table;
442         }
443 
444         /* Request header.  */
445         sg_init_one(&req, &cmd->req, req_size);
446         sgs[out_num++] = &req;
447 
448         /* Data-out buffer.  */
449         if (out) {
450                 /* Place WRITE protection SGLs before Data OUT payload */
451                 if (scsi_prot_sg_count(sc))
452                         sgs[out_num++] = scsi_prot_sglist(sc);
453                 sgs[out_num++] = out->sgl;
454         }
455 
456         /* Response header.  */
457         sg_init_one(&resp, &cmd->resp, resp_size);
458         sgs[out_num + in_num++] = &resp;
459 
460         /* Data-in buffer */
461         if (in) {
462                 /* Place READ protection SGLs before Data IN payload */
463                 if (scsi_prot_sg_count(sc))
464                         sgs[out_num + in_num++] = scsi_prot_sglist(sc);
465                 sgs[out_num + in_num++] = in->sgl;
466         }
467 
468         return virtqueue_add_sgs(vq, sgs, out_num, in_num, cmd, GFP_ATOMIC);
469 }
470 
471 static int virtscsi_kick_cmd(struct virtio_scsi_vq *vq,
472                              struct virtio_scsi_cmd *cmd,
473                              size_t req_size, size_t resp_size)
474 {
475         unsigned long flags;
476         int err;
477         bool needs_kick = false;
478 
479         spin_lock_irqsave(&vq->vq_lock, flags);
480         err = virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size);
481         if (!err)
482                 needs_kick = virtqueue_kick_prepare(vq->vq);
483 
484         spin_unlock_irqrestore(&vq->vq_lock, flags);
485 
486         if (needs_kick)
487                 virtqueue_notify(vq->vq);
488         return err;
489 }
490 
491 static void virtio_scsi_init_hdr(struct virtio_device *vdev,
492                                  struct virtio_scsi_cmd_req *cmd,
493                                  struct scsi_cmnd *sc)
494 {
495         cmd->lun[0] = 1;
496         cmd->lun[1] = sc->device->id;
497         cmd->lun[2] = (sc->device->lun >> 8) | 0x40;
498         cmd->lun[3] = sc->device->lun & 0xff;
499         cmd->tag = cpu_to_virtio64(vdev, (unsigned long)sc);
500         cmd->task_attr = VIRTIO_SCSI_S_SIMPLE;
501         cmd->prio = 0;
502         cmd->crn = 0;
503 }
504 
505 #ifdef CONFIG_BLK_DEV_INTEGRITY
506 static void virtio_scsi_init_hdr_pi(struct virtio_device *vdev,
507                                     struct virtio_scsi_cmd_req_pi *cmd_pi,
508                                     struct scsi_cmnd *sc)
509 {
510         struct request *rq = sc->request;
511         struct blk_integrity *bi;
512 
513         virtio_scsi_init_hdr(vdev, (struct virtio_scsi_cmd_req *)cmd_pi, sc);
514 
515         if (!rq || !scsi_prot_sg_count(sc))
516                 return;
517 
518         bi = blk_get_integrity(rq->rq_disk);
519 
520         if (sc->sc_data_direction == DMA_TO_DEVICE)
521                 cmd_pi->pi_bytesout = cpu_to_virtio32(vdev,
522                                                         blk_rq_sectors(rq) *
523                                                         bi->tuple_size);
524         else if (sc->sc_data_direction == DMA_FROM_DEVICE)
525                 cmd_pi->pi_bytesin = cpu_to_virtio32(vdev,
526                                                        blk_rq_sectors(rq) *
527                                                        bi->tuple_size);
528 }
529 #endif
530 
531 static int virtscsi_queuecommand(struct virtio_scsi *vscsi,
532                                  struct virtio_scsi_vq *req_vq,
533                                  struct scsi_cmnd *sc)
534 {
535         struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
536         struct virtio_scsi_cmd *cmd = scsi_cmd_priv(sc);
537         int req_size;
538 
539         BUG_ON(scsi_sg_count(sc) > shost->sg_tablesize);
540 
541         /* TODO: check feature bit and fail if unsupported?  */
542         BUG_ON(sc->sc_data_direction == DMA_BIDIRECTIONAL);
543 
544         dev_dbg(&sc->device->sdev_gendev,
545                 "cmd %p CDB: %#02x\n", sc, sc->cmnd[0]);
546 
547         memset(cmd, 0, sizeof(*cmd));
548         cmd->sc = sc;
549 
550         BUG_ON(sc->cmd_len > VIRTIO_SCSI_CDB_SIZE);
551 
552 #ifdef CONFIG_BLK_DEV_INTEGRITY
553         if (virtio_has_feature(vscsi->vdev, VIRTIO_SCSI_F_T10_PI)) {
554                 virtio_scsi_init_hdr_pi(vscsi->vdev, &cmd->req.cmd_pi, sc);
555                 memcpy(cmd->req.cmd_pi.cdb, sc->cmnd, sc->cmd_len);
556                 req_size = sizeof(cmd->req.cmd_pi);
557         } else
558 #endif
559         {
560                 virtio_scsi_init_hdr(vscsi->vdev, &cmd->req.cmd, sc);
561                 memcpy(cmd->req.cmd.cdb, sc->cmnd, sc->cmd_len);
562                 req_size = sizeof(cmd->req.cmd);
563         }
564 
565         if (virtscsi_kick_cmd(req_vq, cmd, req_size, sizeof(cmd->resp.cmd)) != 0)
566                 return SCSI_MLQUEUE_HOST_BUSY;
567         return 0;
568 }
569 
570 static int virtscsi_queuecommand_single(struct Scsi_Host *sh,
571                                         struct scsi_cmnd *sc)
572 {
573         struct virtio_scsi *vscsi = shost_priv(sh);
574         struct virtio_scsi_target_state *tgt =
575                                 scsi_target(sc->device)->hostdata;
576 
577         atomic_inc(&tgt->reqs);
578         return virtscsi_queuecommand(vscsi, &vscsi->req_vqs[0], sc);
579 }
580 
581 static struct virtio_scsi_vq *virtscsi_pick_vq_mq(struct virtio_scsi *vscsi,
582                                                   struct scsi_cmnd *sc)
583 {
584         u32 tag = blk_mq_unique_tag(sc->request);
585         u16 hwq = blk_mq_unique_tag_to_hwq(tag);
586 
587         return &vscsi->req_vqs[hwq];
588 }
589 
590 static struct virtio_scsi_vq *virtscsi_pick_vq(struct virtio_scsi *vscsi,
591                                                struct virtio_scsi_target_state *tgt)
592 {
593         struct virtio_scsi_vq *vq;
594         unsigned long flags;
595         u32 queue_num;
596 
597         local_irq_save(flags);
598         if (atomic_inc_return(&tgt->reqs) > 1) {
599                 unsigned long seq;
600 
601                 do {
602                         seq = read_seqcount_begin(&tgt->tgt_seq);
603                         vq = tgt->req_vq;
604                 } while (read_seqcount_retry(&tgt->tgt_seq, seq));
605         } else {
606                 /* no writes can be concurrent because of atomic_t */
607                 write_seqcount_begin(&tgt->tgt_seq);
608 
609                 /* keep previous req_vq if a reader just arrived */
610                 if (unlikely(atomic_read(&tgt->reqs) > 1)) {
611                         vq = tgt->req_vq;
612                         goto unlock;
613                 }
614 
615                 queue_num = smp_processor_id();
616                 while (unlikely(queue_num >= vscsi->num_queues))
617                         queue_num -= vscsi->num_queues;
618                 tgt->req_vq = vq = &vscsi->req_vqs[queue_num];
619  unlock:
620                 write_seqcount_end(&tgt->tgt_seq);
621         }
622         local_irq_restore(flags);
623 
624         return vq;
625 }
626 
627 static int virtscsi_queuecommand_multi(struct Scsi_Host *sh,
628                                        struct scsi_cmnd *sc)
629 {
630         struct virtio_scsi *vscsi = shost_priv(sh);
631         struct virtio_scsi_target_state *tgt =
632                                 scsi_target(sc->device)->hostdata;
633         struct virtio_scsi_vq *req_vq;
634 
635         if (shost_use_blk_mq(sh))
636                 req_vq = virtscsi_pick_vq_mq(vscsi, sc);
637         else
638                 req_vq = virtscsi_pick_vq(vscsi, tgt);
639 
640         return virtscsi_queuecommand(vscsi, req_vq, sc);
641 }
642 
643 static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)
644 {
645         DECLARE_COMPLETION_ONSTACK(comp);
646         int ret = FAILED;
647 
648         cmd->comp = &comp;
649         if (virtscsi_kick_cmd(&vscsi->ctrl_vq, cmd,
650                               sizeof cmd->req.tmf, sizeof cmd->resp.tmf) < 0)
651                 goto out;
652 
653         wait_for_completion(&comp);
654         if (cmd->resp.tmf.response == VIRTIO_SCSI_S_OK ||
655             cmd->resp.tmf.response == VIRTIO_SCSI_S_FUNCTION_SUCCEEDED)
656                 ret = SUCCESS;
657 
658         /*
659          * The spec guarantees that all requests related to the TMF have
660          * been completed, but the callback might not have run yet if
661          * we're using independent interrupts (e.g. MSI).  Poll the
662          * virtqueues once.
663          *
664          * In the abort case, sc->scsi_done will do nothing, because
665          * the block layer must have detected a timeout and as a result
666          * REQ_ATOM_COMPLETE has been set.
667          */
668         virtscsi_poll_requests(vscsi);
669 
670 out:
671         mempool_free(cmd, virtscsi_cmd_pool);
672         return ret;
673 }
674 
675 static int virtscsi_device_reset(struct scsi_cmnd *sc)
676 {
677         struct virtio_scsi *vscsi = shost_priv(sc->device->host);
678         struct virtio_scsi_cmd *cmd;
679 
680         sdev_printk(KERN_INFO, sc->device, "device reset\n");
681         cmd = mempool_alloc(virtscsi_cmd_pool, GFP_NOIO);
682         if (!cmd)
683                 return FAILED;
684 
685         memset(cmd, 0, sizeof(*cmd));
686         cmd->sc = sc;
687         cmd->req.tmf = (struct virtio_scsi_ctrl_tmf_req){
688                 .type = VIRTIO_SCSI_T_TMF,
689                 .subtype = cpu_to_virtio32(vscsi->vdev,
690                                              VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET),
691                 .lun[0] = 1,
692                 .lun[1] = sc->device->id,
693                 .lun[2] = (sc->device->lun >> 8) | 0x40,
694                 .lun[3] = sc->device->lun & 0xff,
695         };
696         return virtscsi_tmf(vscsi, cmd);
697 }
698 
699 /**
700  * virtscsi_change_queue_depth() - Change a virtscsi target's queue depth
701  * @sdev:       Virtscsi target whose queue depth to change
702  * @qdepth:     New queue depth
703  */
704 static int virtscsi_change_queue_depth(struct scsi_device *sdev, int qdepth)
705 {
706         struct Scsi_Host *shost = sdev->host;
707         int max_depth = shost->cmd_per_lun;
708 
709         return scsi_change_queue_depth(sdev, min(max_depth, qdepth));
710 }
711 
712 static int virtscsi_abort(struct scsi_cmnd *sc)
713 {
714         struct virtio_scsi *vscsi = shost_priv(sc->device->host);
715         struct virtio_scsi_cmd *cmd;
716 
717         scmd_printk(KERN_INFO, sc, "abort\n");
718         cmd = mempool_alloc(virtscsi_cmd_pool, GFP_NOIO);
719         if (!cmd)
720                 return FAILED;
721 
722         memset(cmd, 0, sizeof(*cmd));
723         cmd->sc = sc;
724         cmd->req.tmf = (struct virtio_scsi_ctrl_tmf_req){
725                 .type = VIRTIO_SCSI_T_TMF,
726                 .subtype = VIRTIO_SCSI_T_TMF_ABORT_TASK,
727                 .lun[0] = 1,
728                 .lun[1] = sc->device->id,
729                 .lun[2] = (sc->device->lun >> 8) | 0x40,
730                 .lun[3] = sc->device->lun & 0xff,
731                 .tag = cpu_to_virtio64(vscsi->vdev, (unsigned long)sc),
732         };
733         return virtscsi_tmf(vscsi, cmd);
734 }
735 
736 static int virtscsi_target_alloc(struct scsi_target *starget)
737 {
738         struct Scsi_Host *sh = dev_to_shost(starget->dev.parent);
739         struct virtio_scsi *vscsi = shost_priv(sh);
740 
741         struct virtio_scsi_target_state *tgt =
742                                 kmalloc(sizeof(*tgt), GFP_KERNEL);
743         if (!tgt)
744                 return -ENOMEM;
745 
746         seqcount_init(&tgt->tgt_seq);
747         atomic_set(&tgt->reqs, 0);
748         tgt->req_vq = &vscsi->req_vqs[0];
749 
750         starget->hostdata = tgt;
751         return 0;
752 }
753 
754 static void virtscsi_target_destroy(struct scsi_target *starget)
755 {
756         struct virtio_scsi_target_state *tgt = starget->hostdata;
757         kfree(tgt);
758 }
759 
760 static struct scsi_host_template virtscsi_host_template_single = {
761         .module = THIS_MODULE,
762         .name = "Virtio SCSI HBA",
763         .proc_name = "virtio_scsi",
764         .this_id = -1,
765         .cmd_size = sizeof(struct virtio_scsi_cmd),
766         .queuecommand = virtscsi_queuecommand_single,
767         .change_queue_depth = virtscsi_change_queue_depth,
768         .eh_abort_handler = virtscsi_abort,
769         .eh_device_reset_handler = virtscsi_device_reset,
770 
771         .can_queue = 1024,
772         .dma_boundary = UINT_MAX,
773         .use_clustering = ENABLE_CLUSTERING,
774         .target_alloc = virtscsi_target_alloc,
775         .target_destroy = virtscsi_target_destroy,
776         .track_queue_depth = 1,
777 };
778 
779 static struct scsi_host_template virtscsi_host_template_multi = {
780         .module = THIS_MODULE,
781         .name = "Virtio SCSI HBA",
782         .proc_name = "virtio_scsi",
783         .this_id = -1,
784         .cmd_size = sizeof(struct virtio_scsi_cmd),
785         .queuecommand = virtscsi_queuecommand_multi,
786         .change_queue_depth = virtscsi_change_queue_depth,
787         .eh_abort_handler = virtscsi_abort,
788         .eh_device_reset_handler = virtscsi_device_reset,
789 
790         .can_queue = 1024,
791         .dma_boundary = UINT_MAX,
792         .use_clustering = ENABLE_CLUSTERING,
793         .target_alloc = virtscsi_target_alloc,
794         .target_destroy = virtscsi_target_destroy,
795         .track_queue_depth = 1,
796 };
797 
798 #define virtscsi_config_get(vdev, fld) \
799         ({ \
800                 typeof(((struct virtio_scsi_config *)0)->fld) __val; \
801                 virtio_cread(vdev, struct virtio_scsi_config, fld, &__val); \
802                 __val; \
803         })
804 
805 #define virtscsi_config_set(vdev, fld, val) \
806         do { \
807                 typeof(((struct virtio_scsi_config *)0)->fld) __val = (val); \
808                 virtio_cwrite(vdev, struct virtio_scsi_config, fld, &__val); \
809         } while(0)
810 
811 static void __virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity)
812 {
813         int i;
814         int cpu;
815 
816         /* In multiqueue mode, when the number of cpu is equal
817          * to the number of request queues, we let the qeueues
818          * to be private to one cpu by setting the affinity hint
819          * to eliminate the contention.
820          */
821         if ((vscsi->num_queues == 1 ||
822              vscsi->num_queues != num_online_cpus()) && affinity) {
823                 if (vscsi->affinity_hint_set)
824                         affinity = false;
825                 else
826                         return;
827         }
828 
829         if (affinity) {
830                 i = 0;
831                 for_each_online_cpu(cpu) {
832                         virtqueue_set_affinity(vscsi->req_vqs[i].vq, cpu);
833                         i++;
834                 }
835 
836                 vscsi->affinity_hint_set = true;
837         } else {
838                 for (i = 0; i < vscsi->num_queues; i++) {
839                         if (!vscsi->req_vqs[i].vq)
840                                 continue;
841 
842                         virtqueue_set_affinity(vscsi->req_vqs[i].vq, -1);
843                 }
844 
845                 vscsi->affinity_hint_set = false;
846         }
847 }
848 
849 static void virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity)
850 {
851         get_online_cpus();
852         __virtscsi_set_affinity(vscsi, affinity);
853         put_online_cpus();
854 }
855 
856 static int virtscsi_cpu_online(unsigned int cpu, struct hlist_node *node)
857 {
858         struct virtio_scsi *vscsi = hlist_entry_safe(node, struct virtio_scsi,
859                                                      node);
860         __virtscsi_set_affinity(vscsi, true);
861         return 0;
862 }
863 
864 static int virtscsi_cpu_notif_add(struct virtio_scsi *vi)
865 {
866         int ret;
867 
868         ret = cpuhp_state_add_instance(virtioscsi_online, &vi->node);
869         if (ret)
870                 return ret;
871 
872         ret = cpuhp_state_add_instance(CPUHP_VIRT_SCSI_DEAD, &vi->node_dead);
873         if (ret)
874                 cpuhp_state_remove_instance(virtioscsi_online, &vi->node);
875         return ret;
876 }
877 
878 static void virtscsi_cpu_notif_remove(struct virtio_scsi *vi)
879 {
880         cpuhp_state_remove_instance_nocalls(virtioscsi_online, &vi->node);
881         cpuhp_state_remove_instance_nocalls(CPUHP_VIRT_SCSI_DEAD,
882                                             &vi->node_dead);
883 }
884 
885 static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
886                              struct virtqueue *vq)
887 {
888         spin_lock_init(&virtscsi_vq->vq_lock);
889         virtscsi_vq->vq = vq;
890 }
891 
892 static void virtscsi_remove_vqs(struct virtio_device *vdev)
893 {
894         struct Scsi_Host *sh = virtio_scsi_host(vdev);
895         struct virtio_scsi *vscsi = shost_priv(sh);
896 
897         virtscsi_set_affinity(vscsi, false);
898 
899         /* Stop all the virtqueues. */
900         vdev->config->reset(vdev);
901 
902         vdev->config->del_vqs(vdev);
903 }
904 
905 static int virtscsi_init(struct virtio_device *vdev,
906                          struct virtio_scsi *vscsi)
907 {
908         int err;
909         u32 i;
910         u32 num_vqs;
911         vq_callback_t **callbacks;
912         const char **names;
913         struct virtqueue **vqs;
914 
915         num_vqs = vscsi->num_queues + VIRTIO_SCSI_VQ_BASE;
916         vqs = kmalloc(num_vqs * sizeof(struct virtqueue *), GFP_KERNEL);
917         callbacks = kmalloc(num_vqs * sizeof(vq_callback_t *), GFP_KERNEL);
918         names = kmalloc(num_vqs * sizeof(char *), GFP_KERNEL);
919 
920         if (!callbacks || !vqs || !names) {
921                 err = -ENOMEM;
922                 goto out;
923         }
924 
925         callbacks[0] = virtscsi_ctrl_done;
926         callbacks[1] = virtscsi_event_done;
927         names[0] = "control";
928         names[1] = "event";
929         for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs; i++) {
930                 callbacks[i] = virtscsi_req_done;
931                 names[i] = "request";
932         }
933 
934         /* Discover virtqueues and write information to configuration.  */
935         err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names);
936         if (err)
937                 goto out;
938 
939         virtscsi_init_vq(&vscsi->ctrl_vq, vqs[0]);
940         virtscsi_init_vq(&vscsi->event_vq, vqs[1]);
941         for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs; i++)
942                 virtscsi_init_vq(&vscsi->req_vqs[i - VIRTIO_SCSI_VQ_BASE],
943                                  vqs[i]);
944 
945         virtscsi_config_set(vdev, cdb_size, VIRTIO_SCSI_CDB_SIZE);
946         virtscsi_config_set(vdev, sense_size, VIRTIO_SCSI_SENSE_SIZE);
947 
948         err = 0;
949 
950 out:
951         kfree(names);
952         kfree(callbacks);
953         kfree(vqs);
954         if (err)
955                 virtscsi_remove_vqs(vdev);
956         return err;
957 }
958 
959 static int virtscsi_probe(struct virtio_device *vdev)
960 {
961         struct Scsi_Host *shost;
962         struct virtio_scsi *vscsi;
963         int err;
964         u32 sg_elems, num_targets;
965         u32 cmd_per_lun;
966         u32 num_queues;
967         struct scsi_host_template *hostt;
968 
969         if (!vdev->config->get) {
970                 dev_err(&vdev->dev, "%s failure: config access disabled\n",
971                         __func__);
972                 return -EINVAL;
973         }
974 
975         /* We need to know how many queues before we allocate. */
976         num_queues = virtscsi_config_get(vdev, num_queues) ? : 1;
977 
978         num_targets = virtscsi_config_get(vdev, max_target) + 1;
979 
980         if (num_queues == 1)
981                 hostt = &virtscsi_host_template_single;
982         else
983                 hostt = &virtscsi_host_template_multi;
984 
985         shost = scsi_host_alloc(hostt,
986                 sizeof(*vscsi) + sizeof(vscsi->req_vqs[0]) * num_queues);
987         if (!shost)
988                 return -ENOMEM;
989 
990         sg_elems = virtscsi_config_get(vdev, seg_max) ?: 1;
991         shost->sg_tablesize = sg_elems;
992         vscsi = shost_priv(shost);
993         vscsi->vdev = vdev;
994         vscsi->num_queues = num_queues;
995         vdev->priv = shost;
996 
997         err = virtscsi_init(vdev, vscsi);
998         if (err)
999                 goto virtscsi_init_failed;
1000 
1001         err = virtscsi_cpu_notif_add(vscsi);
1002         if (err)
1003                 goto scsi_add_host_failed;
1004 
1005         cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1;
1006         shost->cmd_per_lun = min_t(u32, cmd_per_lun, shost->can_queue);
1007         shost->max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0xFFFF;
1008 
1009         /* LUNs > 256 are reported with format 1, so they go in the range
1010          * 16640-32767.
1011          */
1012         shost->max_lun = virtscsi_config_get(vdev, max_lun) + 1 + 0x4000;
1013         shost->max_id = num_targets;
1014         shost->max_channel = 0;
1015         shost->max_cmd_len = VIRTIO_SCSI_CDB_SIZE;
1016         shost->nr_hw_queues = num_queues;
1017 
1018 #ifdef CONFIG_BLK_DEV_INTEGRITY
1019         if (virtio_has_feature(vdev, VIRTIO_SCSI_F_T10_PI)) {
1020                 int host_prot;
1021 
1022                 host_prot = SHOST_DIF_TYPE1_PROTECTION | SHOST_DIF_TYPE2_PROTECTION |
1023                             SHOST_DIF_TYPE3_PROTECTION | SHOST_DIX_TYPE1_PROTECTION |
1024                             SHOST_DIX_TYPE2_PROTECTION | SHOST_DIX_TYPE3_PROTECTION;
1025 
1026                 scsi_host_set_prot(shost, host_prot);
1027                 scsi_host_set_guard(shost, SHOST_DIX_GUARD_CRC);
1028         }
1029 #endif
1030 
1031         err = scsi_add_host(shost, &vdev->dev);
1032         if (err)
1033                 goto scsi_add_host_failed;
1034 
1035         virtio_device_ready(vdev);
1036 
1037         if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
1038                 virtscsi_kick_event_all(vscsi);
1039 
1040         scsi_scan_host(shost);
1041         return 0;
1042 
1043 scsi_add_host_failed:
1044         vdev->config->del_vqs(vdev);
1045 virtscsi_init_failed:
1046         scsi_host_put(shost);
1047         return err;
1048 }
1049 
1050 static void virtscsi_remove(struct virtio_device *vdev)
1051 {
1052         struct Scsi_Host *shost = virtio_scsi_host(vdev);
1053         struct virtio_scsi *vscsi = shost_priv(shost);
1054 
1055         if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
1056                 virtscsi_cancel_event_work(vscsi);
1057 
1058         scsi_remove_host(shost);
1059 
1060         virtscsi_cpu_notif_remove(vscsi);
1061 
1062         virtscsi_remove_vqs(vdev);
1063         scsi_host_put(shost);
1064 }
1065 
1066 #ifdef CONFIG_PM_SLEEP
1067 static int virtscsi_freeze(struct virtio_device *vdev)
1068 {
1069         struct Scsi_Host *sh = virtio_scsi_host(vdev);
1070         struct virtio_scsi *vscsi = shost_priv(sh);
1071 
1072         virtscsi_cpu_notif_remove(vscsi);
1073         virtscsi_remove_vqs(vdev);
1074         return 0;
1075 }
1076 
1077 static int virtscsi_restore(struct virtio_device *vdev)
1078 {
1079         struct Scsi_Host *sh = virtio_scsi_host(vdev);
1080         struct virtio_scsi *vscsi = shost_priv(sh);
1081         int err;
1082 
1083         err = virtscsi_init(vdev, vscsi);
1084         if (err)
1085                 return err;
1086 
1087         err = virtscsi_cpu_notif_add(vscsi);
1088         if (err) {
1089                 vdev->config->del_vqs(vdev);
1090                 return err;
1091         }
1092         virtio_device_ready(vdev);
1093 
1094         if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
1095                 virtscsi_kick_event_all(vscsi);
1096 
1097         return err;
1098 }
1099 #endif
1100 
1101 static struct virtio_device_id id_table[] = {
1102         { VIRTIO_ID_SCSI, VIRTIO_DEV_ANY_ID },
1103         { 0 },
1104 };
1105 
1106 static unsigned int features[] = {
1107         VIRTIO_SCSI_F_HOTPLUG,
1108         VIRTIO_SCSI_F_CHANGE,
1109 #ifdef CONFIG_BLK_DEV_INTEGRITY
1110         VIRTIO_SCSI_F_T10_PI,
1111 #endif
1112 };
1113 
1114 static struct virtio_driver virtio_scsi_driver = {
1115         .feature_table = features,
1116         .feature_table_size = ARRAY_SIZE(features),
1117         .driver.name = KBUILD_MODNAME,
1118         .driver.owner = THIS_MODULE,
1119         .id_table = id_table,
1120         .probe = virtscsi_probe,
1121 #ifdef CONFIG_PM_SLEEP
1122         .freeze = virtscsi_freeze,
1123         .restore = virtscsi_restore,
1124 #endif
1125         .remove = virtscsi_remove,
1126 };
1127 
1128 static int __init init(void)
1129 {
1130         int ret = -ENOMEM;
1131 
1132         virtscsi_cmd_cache = KMEM_CACHE(virtio_scsi_cmd, 0);
1133         if (!virtscsi_cmd_cache) {
1134                 pr_err("kmem_cache_create() for virtscsi_cmd_cache failed\n");
1135                 goto error;
1136         }
1137 
1138 
1139         virtscsi_cmd_pool =
1140                 mempool_create_slab_pool(VIRTIO_SCSI_MEMPOOL_SZ,
1141                                          virtscsi_cmd_cache);
1142         if (!virtscsi_cmd_pool) {
1143                 pr_err("mempool_create() for virtscsi_cmd_pool failed\n");
1144                 goto error;
1145         }
1146         ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
1147                                       "scsi/virtio:online",
1148                                       virtscsi_cpu_online, NULL);
1149         if (ret < 0)
1150                 goto error;
1151         virtioscsi_online = ret;
1152         ret = cpuhp_setup_state_multi(CPUHP_VIRT_SCSI_DEAD, "scsi/virtio:dead",
1153                                       NULL, virtscsi_cpu_online);
1154         if (ret)
1155                 goto error;
1156         ret = register_virtio_driver(&virtio_scsi_driver);
1157         if (ret < 0)
1158                 goto error;
1159 
1160         return 0;
1161 
1162 error:
1163         if (virtscsi_cmd_pool) {
1164                 mempool_destroy(virtscsi_cmd_pool);
1165                 virtscsi_cmd_pool = NULL;
1166         }
1167         if (virtscsi_cmd_cache) {
1168                 kmem_cache_destroy(virtscsi_cmd_cache);
1169                 virtscsi_cmd_cache = NULL;
1170         }
1171         if (virtioscsi_online)
1172                 cpuhp_remove_multi_state(virtioscsi_online);
1173         cpuhp_remove_multi_state(CPUHP_VIRT_SCSI_DEAD);
1174         return ret;
1175 }
1176 
1177 static void __exit fini(void)
1178 {
1179         unregister_virtio_driver(&virtio_scsi_driver);
1180         cpuhp_remove_multi_state(virtioscsi_online);
1181         cpuhp_remove_multi_state(CPUHP_VIRT_SCSI_DEAD);
1182         mempool_destroy(virtscsi_cmd_pool);
1183         kmem_cache_destroy(virtscsi_cmd_cache);
1184 }
1185 module_init(init);
1186 module_exit(fini);
1187 
1188 MODULE_DEVICE_TABLE(virtio, id_table);
1189 MODULE_DESCRIPTION("Virtio SCSI HBA driver");
1190 MODULE_LICENSE("GPL");
1191 

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