hw/block/block.c

   1 /*
   2  * Common code for block device models
   3  *
   4  * Copyright (C) 2012 Red Hat, Inc.
   5  *
   6  * This work is licensed under the terms of the GNU GPL, version 2 or
   7  * later.  See the COPYING file in the top-level directory.
   8  */
   9
  10 #include "qemu/osdep.h"
  11 #include "sysemu/blockdev.h"
  12 #include "sysemu/block-backend.h"
  13 #include "hw/block/block.h"
  14 #include "qapi/error.h"
  15 #include "qapi/qapi-types-block.h"
  16
  17 /*
  18  * Read the entire contents of @blk into @buf.
  19  * @blk's contents must be @size bytes, and @size must be at most
  20  * BDRV_REQUEST_MAX_BYTES.
  21  * On success, return true.
  22  * On failure, store an error through @errp and return false.
  23  * Note that the error messages do not identify the block backend.
  24  * TODO Since callers don't either, this can result in confusing
  25  * errors.
  26  * This function not intended for actual block devices, which read on
  27  * demand.  It's for things like memory devices that (ab)use a block
  28  * backend to provide persistence.
  29  */
  30 bool blk_check_size_and_read_all(BlockBackend *blk, void *buf, hwaddr size,
  31                                  Error **errp)
  32 {
  33     int64_t blk_len;
  34     int ret;
  35
  36     blk_len = blk_getlength(blk);
  37     if (blk_len < 0) {
  38         error_setg_errno(errp, -blk_len,
  39                          "can't get size of block backend");
  40         return false;
  41     }
  42     if (blk_len != size) {
  43         error_setg(errp, "device requires %" HWADDR_PRIu " bytes, "
  44                    "block backend provides %" PRIu64 " bytes",
  45                    size, blk_len);
  46         return false;
  47     }
  48
  49     /*
  50      * We could loop for @size > BDRV_REQUEST_MAX_BYTES, but if we
  51      * ever get to the point we want to read *gigabytes* here, we
  52      * should probably rework the device to be more like an actual
  53      * block device and read only on demand.
  54      */
  55     assert(size <= BDRV_REQUEST_MAX_BYTES);
  56     ret = blk_pread(blk, 0, buf, size);
  57     if (ret < 0) {
  58         error_setg_errno(errp, -ret, "can't read block backend");
  59         return false;
  60     }
  61     return true;
  62 }
  63
  64 bool blkconf_blocksizes(BlockConf *conf, Error **errp)
  65 {
  66     BlockBackend *blk = conf->blk;
  67     BlockSizes blocksizes;
  68     BlockDriverState *bs;
  69     bool use_blocksizes;
  70     bool use_bs;
  71
  72     switch (conf->backend_defaults) {
  73     case ON_OFF_AUTO_AUTO:
  74         use_blocksizes = !blk_probe_blocksizes(blk, &blocksizes);
  75         use_bs = false;
  76         break;
  77
  78     case ON_OFF_AUTO_ON:
  79         use_blocksizes = !blk_probe_blocksizes(blk, &blocksizes);
  80         bs = blk_bs(blk);
  81         use_bs = bs;
  82         break;
  83
  84     case ON_OFF_AUTO_OFF:
  85         use_blocksizes = false;
  86         use_bs = false;
  87         break;
  88
  89     default:
  90         abort();
  91     }
  92
  93     /* fill in detected values if they are not defined via qemu command line */
  94     if (!conf->physical_block_size) {
  95         if (use_blocksizes) {
  96            conf->physical_block_size = blocksizes.phys;
  97         } else {
  98             conf->physical_block_size = BDRV_SECTOR_SIZE;
  99         }
 100     }
 101     if (!conf->logical_block_size) {
 102         if (use_blocksizes) {
 103             conf->logical_block_size = blocksizes.log;
 104         } else {
 105             conf->logical_block_size = BDRV_SECTOR_SIZE;
 106         }
 107     }
 108     if (use_bs) {
 109         if (!conf->opt_io_size) {
 110             conf->opt_io_size = bs->bl.opt_transfer;
 111         }
 112         if (conf->discard_granularity == -1) {
 113             if (bs->bl.pdiscard_alignment) {
 114                 conf->discard_granularity = bs->bl.pdiscard_alignment;
 115             } else if (bs->bl.request_alignment != 1) {
 116                 conf->discard_granularity = bs->bl.request_alignment;
 117             }
 118         }
 119     }
 120
 121     if (conf->logical_block_size > conf->physical_block_size) {
 122         error_setg(errp,
 123                    "logical_block_size > physical_block_size not supported");
 124         return false;
 125     }
 126
 127     if (!QEMU_IS_ALIGNED(conf->min_io_size, conf->logical_block_size)) {
 128         error_setg(errp,
 129                    "min_io_size must be a multiple of logical_block_size");
 130         return false;
 131     }
 132
 133     /*
 134      * all devices which support min_io_size (scsi and virtio-blk) expose it to
 135      * the guest as a uint16_t in units of logical blocks
 136      */
 137     if (conf->min_io_size / conf->logical_block_size > UINT16_MAX) {
 138         error_setg(errp, "min_io_size must not exceed %u logical blocks",
 139                    UINT16_MAX);
 140         return false;
 141     }
 142
 143     if (!QEMU_IS_ALIGNED(conf->opt_io_size, conf->logical_block_size)) {
 144         error_setg(errp,
 145                    "opt_io_size must be a multiple of logical_block_size");
 146         return false;
 147     }
 148
 149     if (conf->discard_granularity != -1 &&
 150         !QEMU_IS_ALIGNED(conf->discard_granularity,
 151                          conf->logical_block_size)) {
 152         error_setg(errp, "discard_granularity must be "
 153                    "a multiple of logical_block_size");
 154         return false;
 155     }
 156
 157     return true;
 158 }
 159
 160 bool blkconf_apply_backend_options(BlockConf *conf, bool readonly,
 161                                    bool resizable, Error **errp)
 162 {
 163     BlockBackend *blk = conf->blk;
 164     BlockdevOnError rerror, werror;
 165     uint64_t perm, shared_perm;
 166     bool wce;
 167     int ret;
 168
 169     perm = BLK_PERM_CONSISTENT_READ;
 170     if (!readonly) {
 171         perm |= BLK_PERM_WRITE;
 172     }
 173
 174     shared_perm = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
 175     if (resizable) {
 176         shared_perm |= BLK_PERM_RESIZE;
 177     }
 178     if (conf->share_rw) {
 179         shared_perm |= BLK_PERM_WRITE;
 180     }
 181
 182     ret = blk_set_perm(blk, perm, shared_perm, errp);
 183     if (ret < 0) {
 184         return false;
 185     }
 186
 187     switch (conf->wce) {
 188     case ON_OFF_AUTO_ON:    wce = true; break;
 189     case ON_OFF_AUTO_OFF:   wce = false; break;
 190     case ON_OFF_AUTO_AUTO:  wce = blk_enable_write_cache(blk); break;
 191     default:
 192         abort();
 193     }
 194
 195     rerror = conf->rerror;
 196     if (rerror == BLOCKDEV_ON_ERROR_AUTO) {
 197         rerror = blk_get_on_error(blk, true);
 198     }
 199
 200     werror = conf->werror;
 201     if (werror == BLOCKDEV_ON_ERROR_AUTO) {
 202         werror = blk_get_on_error(blk, false);
 203     }
 204
 205     blk_set_enable_write_cache(blk, wce);
 206     blk_set_on_error(blk, rerror, werror);
 207
 208     return true;
 209 }
 210
 211 bool blkconf_geometry(BlockConf *conf, int *ptrans,
 212                       unsigned cyls_max, unsigned heads_max, unsigned secs_max,
 213                       Error **errp)
 214 {
 215     if (!conf->cyls && !conf->heads && !conf->secs) {
 216         hd_geometry_guess(conf->blk,
 217                           &conf->cyls, &conf->heads, &conf->secs,
 218                           ptrans);
 219     } else if (ptrans && *ptrans == BIOS_ATA_TRANSLATION_AUTO) {
 220         *ptrans = hd_bios_chs_auto_trans(conf->cyls, conf->heads, conf->secs);
 221     }
 222     if (conf->cyls || conf->heads || conf->secs) {
 223         if (conf->cyls < 1 || conf->cyls > cyls_max) {
 224             error_setg(errp, "cyls must be between 1 and %u", cyls_max);
 225             return false;
 226         }
 227         if (conf->heads < 1 || conf->heads > heads_max) {
 228             error_setg(errp, "heads must be between 1 and %u", heads_max);
 229             return false;
 230         }
 231         if (conf->secs < 1 || conf->secs > secs_max) {
 232             error_setg(errp, "secs must be between 1 and %u", secs_max);
 233             return false;
 234         }
 235     }
 236     return true;
 237 }