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