hw/virtio-blk.c

   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 <sysemu.h>
  16 #include "virtio-blk.h"
  17 #include "block_int.h"
  18 #ifdef __linux__
  19 # include <scsi/sg.h>
  20 #endif
  21
  22 typedef struct VirtIOBlock
  23 {
  24     VirtIODevice vdev;
  25     BlockDriverState *bs;
  26     VirtQueue *vq;
  27     void *rq;
  28     char serial_str[BLOCK_SERIAL_STRLEN + 1];
  29     QEMUBH *bh;
  30 } VirtIOBlock;
  31
  32 static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
  33 {
  34     return (VirtIOBlock *)vdev;
  35 }
  36
  37 /* store identify data in little endian format
  38  */
  39 static inline void put_le16(uint16_t *p, unsigned int v)
  40 {
  41     *p = cpu_to_le16(v);
  42 }
  43
  44 /* copy to *dst from *src, nul pad dst tail as needed to len bytes
  45  */
  46 static inline void padstr(char *dst, const char *src, int len)
  47 {
  48     while (len--)
  49         *dst++ = *src ? *src++ : '\0';
  50 }
  51
  52 /* setup simulated identify data as appropriate for virtio block device
  53  *
  54  * ref: AT Attachment 8 - ATA/ATAPI Command Set (ATA8-ACS)
  55  */
  56 static inline void virtio_identify_template(struct virtio_blk_config *bc)
  57 {
  58     uint16_t *p = &bc->identify[0];
  59     uint64_t lba_sectors = bc->capacity;
  60
  61     memset(p, 0, sizeof(bc->identify));
  62     put_le16(p + 0, 0x0);                            /* ATA device */
  63     padstr((char *)(p + 23), QEMU_VERSION, 8);       /* firmware revision */
  64     padstr((char *)(p + 27), "QEMU VIRT_BLK", 40);   /* model# */
  65     put_le16(p + 47, 0x80ff);                        /* max xfer 255 sectors */
  66     put_le16(p + 49, 0x0b00);                        /* support IORDY/LBA/DMA */
  67     put_le16(p + 59, 0x1ff);                         /* cur xfer 255 sectors */
  68     put_le16(p + 80, 0x1f0);                         /* support ATA8/7/6/5/4 */
  69     put_le16(p + 81, 0x16);
  70     put_le16(p + 82, 0x400);
  71     put_le16(p + 83, 0x400);
  72     put_le16(p + 100, lba_sectors);
  73     put_le16(p + 101, lba_sectors >> 16);
  74     put_le16(p + 102, lba_sectors >> 32);
  75     put_le16(p + 103, lba_sectors >> 48);
  76 }
  77
  78 typedef struct VirtIOBlockReq
  79 {
  80     VirtIOBlock *dev;
  81     VirtQueueElement elem;
  82     struct virtio_blk_inhdr *in;
  83     struct virtio_blk_outhdr *out;
  84     struct virtio_scsi_inhdr *scsi;
  85     QEMUIOVector qiov;
  86     struct VirtIOBlockReq *next;
  87 } VirtIOBlockReq;
  88
  89 static void virtio_blk_req_complete(VirtIOBlockReq *req, int status)
  90 {
  91     VirtIOBlock *s = req->dev;
  92
  93     req->in->status = status;
  94     virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in));
  95     virtio_notify(&s->vdev, s->vq);
  96
  97     qemu_free(req);
  98 }
  99
 100 static int virtio_blk_handle_write_error(VirtIOBlockReq *req, int error)
 101 {
 102     BlockInterfaceErrorAction action = drive_get_onerror(req->dev->bs);
 103     VirtIOBlock *s = req->dev;
 104
 105     if (action == BLOCK_ERR_IGNORE)
 106         return 0;
 107
 108     if ((error == ENOSPC && action == BLOCK_ERR_STOP_ENOSPC)
 109             || action == BLOCK_ERR_STOP_ANY) {
 110         req->next = s->rq;
 111         s->rq = req;
 112         vm_stop(0);
 113     } else {
 114         virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
 115     }
 116
 117     return 1;
 118 }
 119
 120 static void virtio_blk_rw_complete(void *opaque, int ret)
 121 {
 122     VirtIOBlockReq *req = opaque;
 123
 124     if (ret && (req->out->type & VIRTIO_BLK_T_OUT)) {
 125         if (virtio_blk_handle_write_error(req, -ret))
 126             return;
 127     }
 128
 129     virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
 130 }
 131
 132 static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
 133 {
 134     VirtIOBlockReq *req = qemu_mallocz(sizeof(*req));
 135     req->dev = s;
 136     return req;
 137 }
 138
 139 static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
 140 {
 141     VirtIOBlockReq *req = virtio_blk_alloc_request(s);
 142
 143     if (req != NULL) {
 144         if (!virtqueue_pop(s->vq, &req->elem)) {
 145             qemu_free(req);
 146             return NULL;
 147         }
 148     }
 149
 150     return req;
 151 }
 152
 153 #ifdef __linux__
 154 static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
 155 {
 156     struct sg_io_hdr hdr;
 157     int ret, size = 0;
 158     int status;
 159     int i;
 160
 161     /*
 162      * We require at least one output segment each for the virtio_blk_outhdr
 163      * and the SCSI command block.
 164      *
 165      * We also at least require the virtio_blk_inhdr, the virtio_scsi_inhdr
 166      * and the sense buffer pointer in the input segments.
 167      */
 168     if (req->elem.out_num < 2 || req->elem.in_num < 3) {
 169         virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
 170         return;
 171     }
 172
 173     /*
 174      * No support for bidirection commands yet.
 175      */
 176     if (req->elem.out_num > 2 && req->elem.in_num > 3) {
 177         virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
 178         return;
 179     }
 180
 181     /*
 182      * The scsi inhdr is placed in the second-to-last input segment, just
 183      * before the regular inhdr.
 184      */
 185     req->scsi = (void *)req->elem.in_sg[req->elem.in_num - 2].iov_base;
 186     size = sizeof(*req->in) + sizeof(*req->scsi);
 187
 188     memset(&hdr, 0, sizeof(struct sg_io_hdr));
 189     hdr.interface_id = 'S';
 190     hdr.cmd_len = req->elem.out_sg[1].iov_len;
 191     hdr.cmdp = req->elem.out_sg[1].iov_base;
 192     hdr.dxfer_len = 0;
 193
 194     if (req->elem.out_num > 2) {
 195         /*
 196          * If there are more than the minimally required 2 output segments
 197          * there is write payload starting from the third iovec.
 198          */
 199         hdr.dxfer_direction = SG_DXFER_TO_DEV;
 200         hdr.iovec_count = req->elem.out_num - 2;
 201
 202         for (i = 0; i < hdr.iovec_count; i++)
 203             hdr.dxfer_len += req->elem.out_sg[i + 2].iov_len;
 204
 205         hdr.dxferp = req->elem.out_sg + 2;
 206
 207     } else if (req->elem.in_num > 3) {
 208         /*
 209          * If we have more than 3 input segments the guest wants to actually
 210          * read data.
 211          */
 212         hdr.dxfer_direction = SG_DXFER_FROM_DEV;
 213         hdr.iovec_count = req->elem.in_num - 3;
 214         for (i = 0; i < hdr.iovec_count; i++)
 215             hdr.dxfer_len += req->elem.in_sg[i].iov_len;
 216
 217         hdr.dxferp = req->elem.in_sg;
 218         size += hdr.dxfer_len;
 219     } else {
 220         /*
 221          * Some SCSI commands don't actually transfer any data.
 222          */
 223         hdr.dxfer_direction = SG_DXFER_NONE;
 224     }
 225
 226     hdr.sbp = req->elem.in_sg[req->elem.in_num - 3].iov_base;
 227     hdr.mx_sb_len = req->elem.in_sg[req->elem.in_num - 3].iov_len;
 228     size += hdr.mx_sb_len;
 229
 230     ret = bdrv_ioctl(req->dev->bs, SG_IO, &hdr);
 231     if (ret) {
 232         status = VIRTIO_BLK_S_UNSUPP;
 233         hdr.status = ret;
 234         hdr.resid = hdr.dxfer_len;
 235     } else if (hdr.status) {
 236         status = VIRTIO_BLK_S_IOERR;
 237     } else {
 238         status = VIRTIO_BLK_S_OK;
 239     }
 240
 241     req->scsi->errors = hdr.status;
 242     req->scsi->residual = hdr.resid;
 243     req->scsi->sense_len = hdr.sb_len_wr;
 244     req->scsi->data_len = hdr.dxfer_len;
 245
 246     virtio_blk_req_complete(req, status);
 247 }
 248 #else
 249 static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
 250 {
 251     virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
 252 }
 253 #endif /* __linux__ */
 254
 255 static void virtio_blk_handle_write(VirtIOBlockReq *req)
 256 {
 257     bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
 258                     req->qiov.size / 512, virtio_blk_rw_complete, req);
 259 }
 260
 261 static void virtio_blk_handle_read(VirtIOBlockReq *req)
 262 {
 263     bdrv_aio_readv(req->dev->bs, req->out->sector, &req->qiov,
 264                    req->qiov.size / 512, virtio_blk_rw_complete, req);
 265 }
 266
 267 static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 268 {
 269     VirtIOBlock *s = to_virtio_blk(vdev);
 270     VirtIOBlockReq *req;
 271
 272     while ((req = virtio_blk_get_request(s))) {
 273         if (req->elem.out_num < 1 || req->elem.in_num < 1) {
 274             fprintf(stderr, "virtio-blk missing headers\n");
 275             exit(1);
 276         }
 277
 278         if (req->elem.out_sg[0].iov_len < sizeof(*req->out) ||
 279             req->elem.in_sg[req->elem.in_num - 1].iov_len < sizeof(*req->in)) {
 280             fprintf(stderr, "virtio-blk header not in correct element\n");
 281             exit(1);
 282         }
 283
 284         req->out = (void *)req->elem.out_sg[0].iov_base;
 285         req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
 286
 287         if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
 288             virtio_blk_handle_scsi(req);
 289         } else if (req->out->type & VIRTIO_BLK_T_OUT) {
 290             qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
 291                                      req->elem.out_num - 1);
 292             virtio_blk_handle_write(req);
 293         } else {
 294             qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
 295                                      req->elem.in_num - 1);
 296             virtio_blk_handle_read(req);
 297         }
 298     }
 299     /*
 300      * FIXME: Want to check for completions before returning to guest mode,
 301      * so cached reads and writes are reported as quickly as possible. But
 302      * that should be done in the generic block layer.
 303      */
 304 }
 305
 306 static void virtio_blk_dma_restart_bh(void *opaque)
 307 {
 308     VirtIOBlock *s = opaque;
 309     VirtIOBlockReq *req = s->rq;
 310
 311     qemu_bh_delete(s->bh);
 312     s->bh = NULL;
 313
 314     s->rq = NULL;
 315
 316     while (req) {
 317         virtio_blk_handle_write(req);
 318         req = req->next;
 319     }
 320 }
 321
 322 static void virtio_blk_dma_restart_cb(void *opaque, int running, int reason)
 323 {
 324     VirtIOBlock *s = opaque;
 325
 326     if (!running)
 327         return;
 328
 329     if (!s->bh) {
 330         s->bh = qemu_bh_new(virtio_blk_dma_restart_bh, s);
 331         qemu_bh_schedule(s->bh);
 332     }
 333 }
 334
 335 static void virtio_blk_reset(VirtIODevice *vdev)
 336 {
 337     /*
 338      * This should cancel pending requests, but can't do nicely until there
 339      * are per-device request lists.
 340      */
 341     qemu_aio_flush();
 342 }
 343
 344 /* coalesce internal state, copy to pci i/o region 0
 345  */
 346 static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
 347 {
 348     VirtIOBlock *s = to_virtio_blk(vdev);
 349     struct virtio_blk_config blkcfg;
 350     uint64_t capacity;
 351     int cylinders, heads, secs;
 352
 353     bdrv_get_geometry(s->bs, &capacity);
 354     bdrv_get_geometry_hint(s->bs, &cylinders, &heads, &secs);
 355     memset(&blkcfg, 0, sizeof(blkcfg));
 356     stq_raw(&blkcfg.capacity, capacity);
 357     stl_raw(&blkcfg.seg_max, 128 - 2);
 358     stw_raw(&blkcfg.cylinders, cylinders);
 359     blkcfg.heads = heads;
 360     blkcfg.sectors = secs;
 361     blkcfg.size_max = 0;
 362     virtio_identify_template(&blkcfg);
 363     memcpy(&blkcfg.identify[VIRTIO_BLK_ID_SN], s->serial_str,
 364         VIRTIO_BLK_ID_SN_BYTES);
 365     memcpy(config, &blkcfg, sizeof(blkcfg));
 366 }
 367
 368 static uint32_t virtio_blk_get_features(VirtIODevice *vdev)
 369 {
 370     VirtIOBlock *s = to_virtio_blk(vdev);
 371     uint32_t features = 0;
 372
 373     features |= (1 << VIRTIO_BLK_F_SEG_MAX);
 374     features |= (1 << VIRTIO_BLK_F_GEOMETRY);
 375 #ifdef __linux__
 376     features |= (1 << VIRTIO_BLK_F_SCSI);
 377 #endif
 378     if (strcmp(s->serial_str, "0"))
 379         features |= 1 << VIRTIO_BLK_F_IDENTIFY;
 380
 381     return features;
 382 }
 383
 384 static void virtio_blk_save(QEMUFile *f, void *opaque)
 385 {
 386     VirtIOBlock *s = opaque;
 387     VirtIOBlockReq *req = s->rq;
 388
 389     virtio_save(&s->vdev, f);
 390
 391     while (req) {
 392         qemu_put_sbyte(f, 1);
 393         qemu_put_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
 394         req = req->next;
 395     }
 396     qemu_put_sbyte(f, 0);
 397 }
 398
 399 static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)
 400 {
 401     VirtIOBlock *s = opaque;
 402
 403     if (version_id != 2)
 404         return -EINVAL;
 405
 406     virtio_load(&s->vdev, f);
 407     while (qemu_get_sbyte(f)) {
 408         VirtIOBlockReq *req = virtio_blk_alloc_request(s);
 409         qemu_get_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
 410         req->next = s->rq;
 411         s->rq = req->next;
 412     }
 413
 414     return 0;
 415 }
 416
 417 VirtIODevice *virtio_blk_init(DeviceState *dev)
 418 {
 419     VirtIOBlock *s;
 420     int cylinders, heads, secs;
 421     static int virtio_blk_id;
 422     BlockDriverState *bs;
 423     char *ps;
 424
 425     s = (VirtIOBlock *)virtio_common_init("virtio-blk", VIRTIO_ID_BLOCK,
 426                                           sizeof(struct virtio_blk_config),
 427                                           sizeof(VirtIOBlock));
 428
 429     bs = qdev_init_bdrv(dev, IF_VIRTIO);
 430     s->vdev.get_config = virtio_blk_update_config;
 431     s->vdev.get_features = virtio_blk_get_features;
 432     s->vdev.reset = virtio_blk_reset;
 433     s->bs = bs;
 434     s->rq = NULL;
 435     if (strlen(ps = (char *)drive_get_serial(bs)))
 436         strncpy(s->serial_str, ps, sizeof(s->serial_str));
 437     else
 438         snprintf(s->serial_str, sizeof(s->serial_str), "0");
 439     bs->private = dev;
 440     bdrv_guess_geometry(s->bs, &cylinders, &heads, &secs);
 441     bdrv_set_geometry_hint(s->bs, cylinders, heads, secs);
 442
 443     s->vq = virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);
 444
 445     qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
 446     register_savevm("virtio-blk", virtio_blk_id++, 2,
 447                     virtio_blk_save, virtio_blk_load, s);
 448
 449     return &s->vdev;
 450 }