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1
/*
2
 * Virtio Block Device
3
 *
4
 * Copyright IBM, Corp. 2007
5
 *
6
 * Authors:
7
 *  Anthony Liguori   <aliguori@us.ibm.com>
8
 *
9
 * This work is licensed under the terms of the GNU GPL, version 2.  See
10
 * the COPYING file in the top-level directory.
11
 *
12
 */
13

    
14
#include <qemu-common.h>
15
#include "qemu-error.h"
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#include "trace.h"
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#include "blockdev.h"
18
#include "virtio-blk.h"
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#ifdef __linux__
20
# include <scsi/sg.h>
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#endif
22

    
23
typedef struct VirtIOBlock
24
{
25
    VirtIODevice vdev;
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    BlockDriverState *bs;
27
    VirtQueue *vq;
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    void *rq;
29
    QEMUBH *bh;
30
    BlockConf *conf;
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    unsigned short sector_mask;
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    char sn[BLOCK_SERIAL_STRLEN];
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    DeviceState *qdev;
34
} VirtIOBlock;
35

    
36
static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
37
{
38
    return (VirtIOBlock *)vdev;
39
}
40

    
41
typedef struct VirtIOBlockReq
42
{
43
    VirtIOBlock *dev;
44
    VirtQueueElement elem;
45
    struct virtio_blk_inhdr *in;
46
    struct virtio_blk_outhdr *out;
47
    struct virtio_scsi_inhdr *scsi;
48
    QEMUIOVector qiov;
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    struct VirtIOBlockReq *next;
50
} VirtIOBlockReq;
51

    
52
static void virtio_blk_req_complete(VirtIOBlockReq *req, int status)
53
{
54
    VirtIOBlock *s = req->dev;
55

    
56
    trace_virtio_blk_req_complete(req, status);
57

    
58
    req->in->status = status;
59
    virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in));
60
    virtio_notify(&s->vdev, s->vq);
61

    
62
    qemu_free(req);
63
}
64

    
65
static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
66
    int is_read)
67
{
68
    BlockErrorAction action = bdrv_get_on_error(req->dev->bs, is_read);
69
    VirtIOBlock *s = req->dev;
70

    
71
    if (action == BLOCK_ERR_IGNORE) {
72
        bdrv_mon_event(s->bs, BDRV_ACTION_IGNORE, is_read);
73
        return 0;
74
    }
75

    
76
    if ((error == ENOSPC && action == BLOCK_ERR_STOP_ENOSPC)
77
            || action == BLOCK_ERR_STOP_ANY) {
78
        req->next = s->rq;
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        s->rq = req;
80
        bdrv_mon_event(s->bs, BDRV_ACTION_STOP, is_read);
81
        vm_stop(0);
82
    } else {
83
        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
84
        bdrv_mon_event(s->bs, BDRV_ACTION_REPORT, is_read);
85
    }
86

    
87
    return 1;
88
}
89

    
90
static void virtio_blk_rw_complete(void *opaque, int ret)
91
{
92
    VirtIOBlockReq *req = opaque;
93

    
94
    trace_virtio_blk_rw_complete(req, ret);
95

    
96
    if (ret) {
97
        int is_read = !(req->out->type & VIRTIO_BLK_T_OUT);
98
        if (virtio_blk_handle_rw_error(req, -ret, is_read))
99
            return;
100
    }
101

    
102
    virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
103
}
104

    
105
static void virtio_blk_flush_complete(void *opaque, int ret)
106
{
107
    VirtIOBlockReq *req = opaque;
108

    
109
    if (ret) {
110
        if (virtio_blk_handle_rw_error(req, -ret, 0)) {
111
            return;
112
        }
113
    }
114

    
115
    virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
116
}
117

    
118
static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
119
{
120
    VirtIOBlockReq *req = qemu_malloc(sizeof(*req));
121
    req->dev = s;
122
    req->qiov.size = 0;
123
    req->next = NULL;
124
    return req;
125
}
126

    
127
static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
128
{
129
    VirtIOBlockReq *req = virtio_blk_alloc_request(s);
130

    
131
    if (req != NULL) {
132
        if (!virtqueue_pop(s->vq, &req->elem)) {
133
            qemu_free(req);
134
            return NULL;
135
        }
136
    }
137

    
138
    return req;
139
}
140

    
141
#ifdef __linux__
142
static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
143
{
144
    struct sg_io_hdr hdr;
145
    int ret;
146
    int status;
147
    int i;
148

    
149
    /*
150
     * We require at least one output segment each for the virtio_blk_outhdr
151
     * and the SCSI command block.
152
     *
153
     * We also at least require the virtio_blk_inhdr, the virtio_scsi_inhdr
154
     * and the sense buffer pointer in the input segments.
155
     */
156
    if (req->elem.out_num < 2 || req->elem.in_num < 3) {
157
        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
158
        return;
159
    }
160

    
161
    /*
162
     * No support for bidirection commands yet.
163
     */
164
    if (req->elem.out_num > 2 && req->elem.in_num > 3) {
165
        virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
166
        return;
167
    }
168

    
169
    /*
170
     * The scsi inhdr is placed in the second-to-last input segment, just
171
     * before the regular inhdr.
172
     */
173
    req->scsi = (void *)req->elem.in_sg[req->elem.in_num - 2].iov_base;
174

    
175
    memset(&hdr, 0, sizeof(struct sg_io_hdr));
176
    hdr.interface_id = 'S';
177
    hdr.cmd_len = req->elem.out_sg[1].iov_len;
178
    hdr.cmdp = req->elem.out_sg[1].iov_base;
179
    hdr.dxfer_len = 0;
180

    
181
    if (req->elem.out_num > 2) {
182
        /*
183
         * If there are more than the minimally required 2 output segments
184
         * there is write payload starting from the third iovec.
185
         */
186
        hdr.dxfer_direction = SG_DXFER_TO_DEV;
187
        hdr.iovec_count = req->elem.out_num - 2;
188

    
189
        for (i = 0; i < hdr.iovec_count; i++)
190
            hdr.dxfer_len += req->elem.out_sg[i + 2].iov_len;
191

    
192
        hdr.dxferp = req->elem.out_sg + 2;
193

    
194
    } else if (req->elem.in_num > 3) {
195
        /*
196
         * If we have more than 3 input segments the guest wants to actually
197
         * read data.
198
         */
199
        hdr.dxfer_direction = SG_DXFER_FROM_DEV;
200
        hdr.iovec_count = req->elem.in_num - 3;
201
        for (i = 0; i < hdr.iovec_count; i++)
202
            hdr.dxfer_len += req->elem.in_sg[i].iov_len;
203

    
204
        hdr.dxferp = req->elem.in_sg;
205
    } else {
206
        /*
207
         * Some SCSI commands don't actually transfer any data.
208
         */
209
        hdr.dxfer_direction = SG_DXFER_NONE;
210
    }
211

    
212
    hdr.sbp = req->elem.in_sg[req->elem.in_num - 3].iov_base;
213
    hdr.mx_sb_len = req->elem.in_sg[req->elem.in_num - 3].iov_len;
214

    
215
    ret = bdrv_ioctl(req->dev->bs, SG_IO, &hdr);
216
    if (ret) {
217
        status = VIRTIO_BLK_S_UNSUPP;
218
        hdr.status = ret;
219
        hdr.resid = hdr.dxfer_len;
220
    } else if (hdr.status) {
221
        status = VIRTIO_BLK_S_IOERR;
222
    } else {
223
        status = VIRTIO_BLK_S_OK;
224
    }
225

    
226
    req->scsi->errors = hdr.status;
227
    req->scsi->residual = hdr.resid;
228
    req->scsi->sense_len = hdr.sb_len_wr;
229
    req->scsi->data_len = hdr.dxfer_len;
230

    
231
    virtio_blk_req_complete(req, status);
232
}
233
#else
234
static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
235
{
236
    virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
237
}
238
#endif /* __linux__ */
239

    
240
typedef struct MultiReqBuffer {
241
    BlockRequest        blkreq[32];
242
    unsigned int        num_writes;
243
} MultiReqBuffer;
244

    
245
static void virtio_submit_multiwrite(BlockDriverState *bs, MultiReqBuffer *mrb)
246
{
247
    int i, ret;
248

    
249
    if (!mrb->num_writes) {
250
        return;
251
    }
252

    
253
    ret = bdrv_aio_multiwrite(bs, mrb->blkreq, mrb->num_writes);
254
    if (ret != 0) {
255
        for (i = 0; i < mrb->num_writes; i++) {
256
            if (mrb->blkreq[i].error) {
257
                virtio_blk_rw_complete(mrb->blkreq[i].opaque, -EIO);
258
            }
259
        }
260
    }
261

    
262
    mrb->num_writes = 0;
263
}
264

    
265
static void virtio_blk_handle_flush(VirtIOBlockReq *req, MultiReqBuffer *mrb)
266
{
267
    BlockDriverAIOCB *acb;
268

    
269
    /*
270
     * Make sure all outstanding writes are posted to the backing device.
271
     */
272
    virtio_submit_multiwrite(req->dev->bs, mrb);
273

    
274
    acb = bdrv_aio_flush(req->dev->bs, virtio_blk_flush_complete, req);
275
    if (!acb) {
276
        virtio_blk_flush_complete(req, -EIO);
277
    }
278
}
279

    
280
static void virtio_blk_handle_write(VirtIOBlockReq *req, MultiReqBuffer *mrb)
281
{
282
    BlockRequest *blkreq;
283

    
284
    trace_virtio_blk_handle_write(req, req->out->sector, req->qiov.size / 512);
285

    
286
    if (req->out->sector & req->dev->sector_mask) {
287
        virtio_blk_rw_complete(req, -EIO);
288
        return;
289
    }
290

    
291
    if (mrb->num_writes == 32) {
292
        virtio_submit_multiwrite(req->dev->bs, mrb);
293
    }
294

    
295
    blkreq = &mrb->blkreq[mrb->num_writes];
296
    blkreq->sector = req->out->sector;
297
    blkreq->nb_sectors = req->qiov.size / BDRV_SECTOR_SIZE;
298
    blkreq->qiov = &req->qiov;
299
    blkreq->cb = virtio_blk_rw_complete;
300
    blkreq->opaque = req;
301
    blkreq->error = 0;
302

    
303
    mrb->num_writes++;
304
}
305

    
306
static void virtio_blk_handle_read(VirtIOBlockReq *req)
307
{
308
    BlockDriverAIOCB *acb;
309

    
310
    if (req->out->sector & req->dev->sector_mask) {
311
        virtio_blk_rw_complete(req, -EIO);
312
        return;
313
    }
314

    
315
    acb = bdrv_aio_readv(req->dev->bs, req->out->sector, &req->qiov,
316
                         req->qiov.size / BDRV_SECTOR_SIZE,
317
                         virtio_blk_rw_complete, req);
318
    if (!acb) {
319
        virtio_blk_rw_complete(req, -EIO);
320
    }
321
}
322

    
323
static void virtio_blk_handle_request(VirtIOBlockReq *req,
324
    MultiReqBuffer *mrb)
325
{
326
    if (req->elem.out_num < 1 || req->elem.in_num < 1) {
327
        error_report("virtio-blk missing headers");
328
        exit(1);
329
    }
330

    
331
    if (req->elem.out_sg[0].iov_len < sizeof(*req->out) ||
332
        req->elem.in_sg[req->elem.in_num - 1].iov_len < sizeof(*req->in)) {
333
        error_report("virtio-blk header not in correct element");
334
        exit(1);
335
    }
336

    
337
    req->out = (void *)req->elem.out_sg[0].iov_base;
338
    req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
339

    
340
    if (req->out->type & VIRTIO_BLK_T_FLUSH) {
341
        virtio_blk_handle_flush(req, mrb);
342
    } else if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
343
        virtio_blk_handle_scsi(req);
344
    } else if (req->out->type & VIRTIO_BLK_T_GET_ID) {
345
        VirtIOBlock *s = req->dev;
346

    
347
        memcpy(req->elem.in_sg[0].iov_base, s->sn,
348
               MIN(req->elem.in_sg[0].iov_len, sizeof(s->sn)));
349
        virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
350
    } else if (req->out->type & VIRTIO_BLK_T_OUT) {
351
        qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
352
                                 req->elem.out_num - 1);
353
        virtio_blk_handle_write(req, mrb);
354
    } else {
355
        qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
356
                                 req->elem.in_num - 1);
357
        virtio_blk_handle_read(req);
358
    }
359
}
360

    
361
static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
362
{
363
    VirtIOBlock *s = to_virtio_blk(vdev);
364
    VirtIOBlockReq *req;
365
    MultiReqBuffer mrb = {
366
        .num_writes = 0,
367
    };
368

    
369
    while ((req = virtio_blk_get_request(s))) {
370
        virtio_blk_handle_request(req, &mrb);
371
    }
372

    
373
    virtio_submit_multiwrite(s->bs, &mrb);
374

    
375
    /*
376
     * FIXME: Want to check for completions before returning to guest mode,
377
     * so cached reads and writes are reported as quickly as possible. But
378
     * that should be done in the generic block layer.
379
     */
380
}
381

    
382
static void virtio_blk_dma_restart_bh(void *opaque)
383
{
384
    VirtIOBlock *s = opaque;
385
    VirtIOBlockReq *req = s->rq;
386
    MultiReqBuffer mrb = {
387
        .num_writes = 0,
388
    };
389

    
390
    qemu_bh_delete(s->bh);
391
    s->bh = NULL;
392

    
393
    s->rq = NULL;
394

    
395
    while (req) {
396
        virtio_blk_handle_request(req, &mrb);
397
        req = req->next;
398
    }
399

    
400
    virtio_submit_multiwrite(s->bs, &mrb);
401
}
402

    
403
static void virtio_blk_dma_restart_cb(void *opaque, int running, int reason)
404
{
405
    VirtIOBlock *s = opaque;
406

    
407
    if (!running)
408
        return;
409

    
410
    if (!s->bh) {
411
        s->bh = qemu_bh_new(virtio_blk_dma_restart_bh, s);
412
        qemu_bh_schedule(s->bh);
413
    }
414
}
415

    
416
static void virtio_blk_reset(VirtIODevice *vdev)
417
{
418
    /*
419
     * This should cancel pending requests, but can't do nicely until there
420
     * are per-device request lists.
421
     */
422
    qemu_aio_flush();
423
}
424

    
425
/* coalesce internal state, copy to pci i/o region 0
426
 */
427
static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
428
{
429
    VirtIOBlock *s = to_virtio_blk(vdev);
430
    struct virtio_blk_config blkcfg;
431
    uint64_t capacity;
432
    int cylinders, heads, secs;
433

    
434
    bdrv_get_geometry(s->bs, &capacity);
435
    bdrv_get_geometry_hint(s->bs, &cylinders, &heads, &secs);
436
    memset(&blkcfg, 0, sizeof(blkcfg));
437
    stq_raw(&blkcfg.capacity, capacity);
438
    stl_raw(&blkcfg.seg_max, 128 - 2);
439
    stw_raw(&blkcfg.cylinders, cylinders);
440
    blkcfg.heads = heads;
441
    blkcfg.sectors = secs & ~s->sector_mask;
442
    blkcfg.blk_size = s->conf->logical_block_size;
443
    blkcfg.size_max = 0;
444
    blkcfg.physical_block_exp = get_physical_block_exp(s->conf);
445
    blkcfg.alignment_offset = 0;
446
    blkcfg.min_io_size = s->conf->min_io_size / blkcfg.blk_size;
447
    blkcfg.opt_io_size = s->conf->opt_io_size / blkcfg.blk_size;
448
    memcpy(config, &blkcfg, sizeof(struct virtio_blk_config));
449
}
450

    
451
static uint32_t virtio_blk_get_features(VirtIODevice *vdev, uint32_t features)
452
{
453
    VirtIOBlock *s = to_virtio_blk(vdev);
454

    
455
    features |= (1 << VIRTIO_BLK_F_SEG_MAX);
456
    features |= (1 << VIRTIO_BLK_F_GEOMETRY);
457
    features |= (1 << VIRTIO_BLK_F_TOPOLOGY);
458
    features |= (1 << VIRTIO_BLK_F_BLK_SIZE);
459

    
460
    if (bdrv_enable_write_cache(s->bs))
461
        features |= (1 << VIRTIO_BLK_F_WCACHE);
462
    
463
    if (bdrv_is_read_only(s->bs))
464
        features |= 1 << VIRTIO_BLK_F_RO;
465

    
466
    return features;
467
}
468

    
469
static void virtio_blk_save(QEMUFile *f, void *opaque)
470
{
471
    VirtIOBlock *s = opaque;
472
    VirtIOBlockReq *req = s->rq;
473

    
474
    virtio_save(&s->vdev, f);
475
    
476
    while (req) {
477
        qemu_put_sbyte(f, 1);
478
        qemu_put_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
479
        req = req->next;
480
    }
481
    qemu_put_sbyte(f, 0);
482
}
483

    
484
static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)
485
{
486
    VirtIOBlock *s = opaque;
487

    
488
    if (version_id != 2)
489
        return -EINVAL;
490

    
491
    virtio_load(&s->vdev, f);
492
    while (qemu_get_sbyte(f)) {
493
        VirtIOBlockReq *req = virtio_blk_alloc_request(s);
494
        qemu_get_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
495
        req->next = s->rq;
496
        s->rq = req;
497

    
498
        virtqueue_map_sg(req->elem.in_sg, req->elem.in_addr,
499
            req->elem.in_num, 1);
500
        virtqueue_map_sg(req->elem.out_sg, req->elem.out_addr,
501
            req->elem.out_num, 0);
502
    }
503

    
504
    return 0;
505
}
506

    
507
VirtIODevice *virtio_blk_init(DeviceState *dev, BlockConf *conf)
508
{
509
    VirtIOBlock *s;
510
    int cylinders, heads, secs;
511
    static int virtio_blk_id;
512
    DriveInfo *dinfo;
513

    
514
    if (!conf->bs) {
515
        error_report("virtio-blk-pci: drive property not set");
516
        return NULL;
517
    }
518
    if (!bdrv_is_inserted(conf->bs)) {
519
        error_report("Device needs media, but drive is empty");
520
        return NULL;
521
    }
522

    
523
    s = (VirtIOBlock *)virtio_common_init("virtio-blk", VIRTIO_ID_BLOCK,
524
                                          sizeof(struct virtio_blk_config),
525
                                          sizeof(VirtIOBlock));
526

    
527
    s->vdev.get_config = virtio_blk_update_config;
528
    s->vdev.get_features = virtio_blk_get_features;
529
    s->vdev.reset = virtio_blk_reset;
530
    s->bs = conf->bs;
531
    s->conf = conf;
532
    s->rq = NULL;
533
    s->sector_mask = (s->conf->logical_block_size / BDRV_SECTOR_SIZE) - 1;
534
    bdrv_guess_geometry(s->bs, &cylinders, &heads, &secs);
535

    
536
    /* NB: per existing s/n string convention the string is terminated
537
     * by '\0' only when less than sizeof (s->sn)
538
     */
539
    dinfo = drive_get_by_blockdev(s->bs);
540
    strncpy(s->sn, dinfo->serial, sizeof (s->sn));
541

    
542
    s->vq = virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);
543

    
544
    qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
545
    s->qdev = dev;
546
    register_savevm(dev, "virtio-blk", virtio_blk_id++, 2,
547
                    virtio_blk_save, virtio_blk_load, s);
548
    bdrv_set_removable(s->bs, 0);
549
    s->bs->buffer_alignment = conf->logical_block_size;
550

    
551
    return &s->vdev;
552
}
553

    
554
void virtio_blk_exit(VirtIODevice *vdev)
555
{
556
    VirtIOBlock *s = to_virtio_blk(vdev);
557
    unregister_savevm(s->qdev, "virtio-blk", s);
558
}