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1
/*
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 * Virtio Block Device
3
 *
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 * Copyright IBM, Corp. 2007
5
 *
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 * Authors:
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 *  Anthony Liguori   <aliguori@us.ibm.com>
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 *
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 * This work is licensed under the terms of the GNU GPL, version 2.  See
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 * the COPYING file in the top-level directory.
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 *
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 */
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14
#include <qemu-common.h>
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#include <sysemu.h>
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#include "virtio-blk.h"
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#include "block_int.h"
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#ifdef __linux__
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# include <scsi/sg.h>
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#endif
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22
typedef struct VirtIOBlock
23
{
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    VirtIODevice vdev;
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    BlockDriverState *bs;
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    VirtQueue *vq;
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    void *rq;
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    char serial_str[BLOCK_SERIAL_STRLEN + 1];
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    QEMUBH *bh;
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    size_t config_size;
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} VirtIOBlock;
32

    
33
static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
34
{
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    return (VirtIOBlock *)vdev;
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}
37

    
38
/* store identify data in little endian format
39
 */
40
static inline void put_le16(uint16_t *p, unsigned int v)
41
{
42
    *p = cpu_to_le16(v);
43
}
44

    
45
/* copy to *dst from *src, nul pad dst tail as needed to len bytes
46
 */
47
static inline void padstr(char *dst, const char *src, int len)
48
{
49
    while (len--)
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        *dst++ = *src ? *src++ : '\0';
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}
52

    
53
/* setup simulated identify data as appropriate for virtio block device
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 *
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 * ref: AT Attachment 8 - ATA/ATAPI Command Set (ATA8-ACS)
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 */
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static inline void virtio_identify_template(struct virtio_blk_config *bc)
58
{
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    uint16_t *p = &bc->identify[0];
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    uint64_t lba_sectors = bc->capacity;
61

    
62
    memset(p, 0, sizeof(bc->identify));
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    put_le16(p + 0, 0x0);                            /* ATA device */
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    padstr((char *)(p + 23), QEMU_VERSION, 8);       /* firmware revision */
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    padstr((char *)(p + 27), "QEMU VIRT_BLK", 40);   /* model# */
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    put_le16(p + 47, 0x80ff);                        /* max xfer 255 sectors */
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    put_le16(p + 49, 0x0b00);                        /* support IORDY/LBA/DMA */
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    put_le16(p + 59, 0x1ff);                         /* cur xfer 255 sectors */
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    put_le16(p + 80, 0x1f0);                         /* support ATA8/7/6/5/4 */
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    put_le16(p + 81, 0x16);
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    put_le16(p + 82, 0x400);
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    put_le16(p + 83, 0x400);
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    put_le16(p + 100, lba_sectors);
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    put_le16(p + 101, lba_sectors >> 16);
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    put_le16(p + 102, lba_sectors >> 32);
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    put_le16(p + 103, lba_sectors >> 48);
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}
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typedef struct VirtIOBlockReq
80
{
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    VirtIOBlock *dev;
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    VirtQueueElement elem;
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    struct virtio_blk_inhdr *in;
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    struct virtio_blk_outhdr *out;
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    struct virtio_scsi_inhdr *scsi;
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    QEMUIOVector qiov;
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    struct VirtIOBlockReq *next;
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} VirtIOBlockReq;
89

    
90
static void virtio_blk_req_complete(VirtIOBlockReq *req, int status)
91
{
92
    VirtIOBlock *s = req->dev;
93

    
94
    req->in->status = status;
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    virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in));
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    virtio_notify(&s->vdev, s->vq);
97

    
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    qemu_free(req);
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}
100

    
101
static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
102
    int is_read)
103
{
104
    BlockInterfaceErrorAction action =
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        drive_get_on_error(req->dev->bs, is_read);
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    VirtIOBlock *s = req->dev;
107

    
108
    if (action == BLOCK_ERR_IGNORE)
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        return 0;
110

    
111
    if ((error == ENOSPC && action == BLOCK_ERR_STOP_ENOSPC)
112
            || action == BLOCK_ERR_STOP_ANY) {
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        req->next = s->rq;
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        s->rq = req;
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        vm_stop(0);
116
    } else {
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        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
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    }
119

    
120
    return 1;
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}
122

    
123
static void virtio_blk_rw_complete(void *opaque, int ret)
124
{
125
    VirtIOBlockReq *req = opaque;
126

    
127
    if (ret) {
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        int is_read = !(req->out->type & VIRTIO_BLK_T_OUT);
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        if (virtio_blk_handle_rw_error(req, -ret, is_read))
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            return;
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    }
132

    
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    virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
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}
135

    
136
static void virtio_blk_flush_complete(void *opaque, int ret)
137
{
138
    VirtIOBlockReq *req = opaque;
139

    
140
    virtio_blk_req_complete(req, ret ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK);
141
}
142

    
143
static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
144
{
145
    VirtIOBlockReq *req = qemu_mallocz(sizeof(*req));
146
    req->dev = s;
147
    return req;
148
}
149

    
150
static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
151
{
152
    VirtIOBlockReq *req = virtio_blk_alloc_request(s);
153

    
154
    if (req != NULL) {
155
        if (!virtqueue_pop(s->vq, &req->elem)) {
156
            qemu_free(req);
157
            return NULL;
158
        }
159
    }
160

    
161
    return req;
162
}
163

    
164
#ifdef __linux__
165
static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
166
{
167
    struct sg_io_hdr hdr;
168
    int ret;
169
    int status;
170
    int i;
171

    
172
    /*
173
     * We require at least one output segment each for the virtio_blk_outhdr
174
     * and the SCSI command block.
175
     *
176
     * We also at least require the virtio_blk_inhdr, the virtio_scsi_inhdr
177
     * and the sense buffer pointer in the input segments.
178
     */
179
    if (req->elem.out_num < 2 || req->elem.in_num < 3) {
180
        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
181
        return;
182
    }
183

    
184
    /*
185
     * No support for bidirection commands yet.
186
     */
187
    if (req->elem.out_num > 2 && req->elem.in_num > 3) {
188
        virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
189
        return;
190
    }
191

    
192
    /*
193
     * The scsi inhdr is placed in the second-to-last input segment, just
194
     * before the regular inhdr.
195
     */
196
    req->scsi = (void *)req->elem.in_sg[req->elem.in_num - 2].iov_base;
197

    
198
    memset(&hdr, 0, sizeof(struct sg_io_hdr));
199
    hdr.interface_id = 'S';
200
    hdr.cmd_len = req->elem.out_sg[1].iov_len;
201
    hdr.cmdp = req->elem.out_sg[1].iov_base;
202
    hdr.dxfer_len = 0;
203

    
204
    if (req->elem.out_num > 2) {
205
        /*
206
         * If there are more than the minimally required 2 output segments
207
         * there is write payload starting from the third iovec.
208
         */
209
        hdr.dxfer_direction = SG_DXFER_TO_DEV;
210
        hdr.iovec_count = req->elem.out_num - 2;
211

    
212
        for (i = 0; i < hdr.iovec_count; i++)
213
            hdr.dxfer_len += req->elem.out_sg[i + 2].iov_len;
214

    
215
        hdr.dxferp = req->elem.out_sg + 2;
216

    
217
    } else if (req->elem.in_num > 3) {
218
        /*
219
         * If we have more than 3 input segments the guest wants to actually
220
         * read data.
221
         */
222
        hdr.dxfer_direction = SG_DXFER_FROM_DEV;
223
        hdr.iovec_count = req->elem.in_num - 3;
224
        for (i = 0; i < hdr.iovec_count; i++)
225
            hdr.dxfer_len += req->elem.in_sg[i].iov_len;
226

    
227
        hdr.dxferp = req->elem.in_sg;
228
    } else {
229
        /*
230
         * Some SCSI commands don't actually transfer any data.
231
         */
232
        hdr.dxfer_direction = SG_DXFER_NONE;
233
    }
234

    
235
    hdr.sbp = req->elem.in_sg[req->elem.in_num - 3].iov_base;
236
    hdr.mx_sb_len = req->elem.in_sg[req->elem.in_num - 3].iov_len;
237

    
238
    ret = bdrv_ioctl(req->dev->bs, SG_IO, &hdr);
239
    if (ret) {
240
        status = VIRTIO_BLK_S_UNSUPP;
241
        hdr.status = ret;
242
        hdr.resid = hdr.dxfer_len;
243
    } else if (hdr.status) {
244
        status = VIRTIO_BLK_S_IOERR;
245
    } else {
246
        status = VIRTIO_BLK_S_OK;
247
    }
248

    
249
    req->scsi->errors = hdr.status;
250
    req->scsi->residual = hdr.resid;
251
    req->scsi->sense_len = hdr.sb_len_wr;
252
    req->scsi->data_len = hdr.dxfer_len;
253

    
254
    virtio_blk_req_complete(req, status);
255
}
256
#else
257
static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
258
{
259
    virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
260
}
261
#endif /* __linux__ */
262

    
263
static void do_multiwrite(BlockDriverState *bs, BlockRequest *blkreq,
264
    int num_writes)
265
{
266
    int i, ret;
267
    ret = bdrv_aio_multiwrite(bs, blkreq, num_writes);
268

    
269
    if (ret != 0) {
270
        for (i = 0; i < num_writes; i++) {
271
            if (blkreq[i].error) {
272
                virtio_blk_req_complete(blkreq[i].opaque, VIRTIO_BLK_S_IOERR);
273
            }
274
        }
275
    }
276
}
277

    
278
static void virtio_blk_handle_flush(VirtIOBlockReq *req)
279
{
280
    BlockDriverAIOCB *acb;
281

    
282
    acb = bdrv_aio_flush(req->dev->bs, virtio_blk_flush_complete, req);
283
    if (!acb) {
284
        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
285
    }
286
}
287

    
288
static void virtio_blk_handle_write(BlockRequest *blkreq, int *num_writes,
289
    VirtIOBlockReq *req, BlockDriverState **old_bs)
290
{
291
    if (req->dev->bs != *old_bs || *num_writes == 32) {
292
        if (*old_bs != NULL) {
293
            do_multiwrite(*old_bs, blkreq, *num_writes);
294
        }
295
        *num_writes = 0;
296
        *old_bs = req->dev->bs;
297
    }
298

    
299
    blkreq[*num_writes].sector = req->out->sector;
300
    blkreq[*num_writes].nb_sectors = req->qiov.size / 512;
301
    blkreq[*num_writes].qiov = &req->qiov;
302
    blkreq[*num_writes].cb = virtio_blk_rw_complete;
303
    blkreq[*num_writes].opaque = req;
304
    blkreq[*num_writes].error = 0;
305

    
306
    (*num_writes)++;
307
}
308

    
309
static void virtio_blk_handle_read(VirtIOBlockReq *req)
310
{
311
    BlockDriverAIOCB *acb;
312

    
313
    acb = bdrv_aio_readv(req->dev->bs, req->out->sector, &req->qiov,
314
                         req->qiov.size / 512, virtio_blk_rw_complete, req);
315
    if (!acb) {
316
        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
317
    }
318
}
319

    
320
static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
321
{
322
    VirtIOBlock *s = to_virtio_blk(vdev);
323
    VirtIOBlockReq *req;
324
    BlockRequest blkreq[32];
325
    int num_writes = 0;
326
    BlockDriverState *old_bs = NULL;
327

    
328
    while ((req = virtio_blk_get_request(s))) {
329
        if (req->elem.out_num < 1 || req->elem.in_num < 1) {
330
            fprintf(stderr, "virtio-blk missing headers\n");
331
            exit(1);
332
        }
333

    
334
        if (req->elem.out_sg[0].iov_len < sizeof(*req->out) ||
335
            req->elem.in_sg[req->elem.in_num - 1].iov_len < sizeof(*req->in)) {
336
            fprintf(stderr, "virtio-blk header not in correct element\n");
337
            exit(1);
338
        }
339

    
340
        req->out = (void *)req->elem.out_sg[0].iov_base;
341
        req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
342

    
343
        if (req->out->type & VIRTIO_BLK_T_FLUSH) {
344
            virtio_blk_handle_flush(req);
345
        } else if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
346
            virtio_blk_handle_scsi(req);
347
        } else if (req->out->type & VIRTIO_BLK_T_OUT) {
348
            qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
349
                                     req->elem.out_num - 1);
350
            virtio_blk_handle_write(blkreq, &num_writes, req, &old_bs);
351
        } else {
352
            qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
353
                                     req->elem.in_num - 1);
354
            virtio_blk_handle_read(req);
355
        }
356
    }
357

    
358
    if (num_writes > 0) {
359
        do_multiwrite(old_bs, blkreq, num_writes);
360
    }
361

    
362
    /*
363
     * FIXME: Want to check for completions before returning to guest mode,
364
     * so cached reads and writes are reported as quickly as possible. But
365
     * that should be done in the generic block layer.
366
     */
367
}
368

    
369
static void virtio_blk_dma_restart_bh(void *opaque)
370
{
371
    VirtIOBlock *s = opaque;
372
    VirtIOBlockReq *req = s->rq;
373

    
374
    qemu_bh_delete(s->bh);
375
    s->bh = NULL;
376

    
377
    s->rq = NULL;
378

    
379
    while (req) {
380
        bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
381
            req->qiov.size / 512, virtio_blk_rw_complete, req);
382
        req = req->next;
383
    }
384
}
385

    
386
static void virtio_blk_dma_restart_cb(void *opaque, int running, int reason)
387
{
388
    VirtIOBlock *s = opaque;
389

    
390
    if (!running)
391
        return;
392

    
393
    if (!s->bh) {
394
        s->bh = qemu_bh_new(virtio_blk_dma_restart_bh, s);
395
        qemu_bh_schedule(s->bh);
396
    }
397
}
398

    
399
static void virtio_blk_reset(VirtIODevice *vdev)
400
{
401
    /*
402
     * This should cancel pending requests, but can't do nicely until there
403
     * are per-device request lists.
404
     */
405
    qemu_aio_flush();
406
}
407

    
408
/* coalesce internal state, copy to pci i/o region 0
409
 */
410
static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
411
{
412
    VirtIOBlock *s = to_virtio_blk(vdev);
413
    struct virtio_blk_config blkcfg;
414
    uint64_t capacity;
415
    int cylinders, heads, secs;
416

    
417
    bdrv_get_geometry(s->bs, &capacity);
418
    bdrv_get_geometry_hint(s->bs, &cylinders, &heads, &secs);
419
    memset(&blkcfg, 0, sizeof(blkcfg));
420
    stq_raw(&blkcfg.capacity, capacity);
421
    stl_raw(&blkcfg.seg_max, 128 - 2);
422
    stw_raw(&blkcfg.cylinders, cylinders);
423
    blkcfg.heads = heads;
424
    blkcfg.sectors = secs;
425
    blkcfg.size_max = 0;
426
    virtio_identify_template(&blkcfg);
427
    memcpy(&blkcfg.identify[VIRTIO_BLK_ID_SN], s->serial_str,
428
        VIRTIO_BLK_ID_SN_BYTES);
429
    memcpy(config, &blkcfg, s->config_size);
430
}
431

    
432
static uint32_t virtio_blk_get_features(VirtIODevice *vdev, uint32_t features)
433
{
434
    VirtIOBlock *s = to_virtio_blk(vdev);
435

    
436
    features |= (1 << VIRTIO_BLK_F_SEG_MAX);
437
    features |= (1 << VIRTIO_BLK_F_GEOMETRY);
438

    
439
    if (bdrv_enable_write_cache(s->bs))
440
        features |= (1 << VIRTIO_BLK_F_WCACHE);
441
    if (strcmp(s->serial_str, "0"))
442
        features |= 1 << VIRTIO_BLK_F_IDENTIFY;
443
    
444
    if (bdrv_is_read_only(s->bs))
445
        features |= 1 << VIRTIO_BLK_F_RO;
446

    
447
    return features;
448
}
449

    
450
static void virtio_blk_save(QEMUFile *f, void *opaque)
451
{
452
    VirtIOBlock *s = opaque;
453
    VirtIOBlockReq *req = s->rq;
454

    
455
    virtio_save(&s->vdev, f);
456
    
457
    while (req) {
458
        qemu_put_sbyte(f, 1);
459
        qemu_put_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
460
        req = req->next;
461
    }
462
    qemu_put_sbyte(f, 0);
463
}
464

    
465
static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)
466
{
467
    VirtIOBlock *s = opaque;
468

    
469
    if (version_id != 2)
470
        return -EINVAL;
471

    
472
    virtio_load(&s->vdev, f);
473
    while (qemu_get_sbyte(f)) {
474
        VirtIOBlockReq *req = virtio_blk_alloc_request(s);
475
        qemu_get_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
476
        req->next = s->rq;
477
        s->rq = req->next;
478
    }
479

    
480
    return 0;
481
}
482

    
483
VirtIODevice *virtio_blk_init(DeviceState *dev, DriveInfo *dinfo)
484
{
485
    VirtIOBlock *s;
486
    int cylinders, heads, secs;
487
    static int virtio_blk_id;
488
    char *ps = (char *)drive_get_serial(dinfo->bdrv);
489
    size_t size = strlen(ps) ? sizeof(struct virtio_blk_config) :
490
            offsetof(struct virtio_blk_config, _blk_size);
491

    
492
    s = (VirtIOBlock *)virtio_common_init("virtio-blk", VIRTIO_ID_BLOCK,
493
                                          size,
494
                                          sizeof(VirtIOBlock));
495

    
496
    s->config_size = size;
497
    s->vdev.get_config = virtio_blk_update_config;
498
    s->vdev.get_features = virtio_blk_get_features;
499
    s->vdev.reset = virtio_blk_reset;
500
    s->bs = dinfo->bdrv;
501
    s->rq = NULL;
502
    if (strlen(ps))
503
        strncpy(s->serial_str, ps, sizeof(s->serial_str));
504
    else
505
        snprintf(s->serial_str, sizeof(s->serial_str), "0");
506
    bdrv_guess_geometry(s->bs, &cylinders, &heads, &secs);
507
    bdrv_set_geometry_hint(s->bs, cylinders, heads, secs);
508

    
509
    s->vq = virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);
510

    
511
    qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
512
    register_savevm("virtio-blk", virtio_blk_id++, 2,
513
                    virtio_blk_save, virtio_blk_load, s);
514

    
515
    return &s->vdev;
516
}