qemu/hw/block/block.c
Markus Armbruster 06f1521795 pflash: Require backend size to match device, improve errors
We reject undersized backends with a rather enigmatic "failed to read
the initial flash content" error.  For instance:

    $ qemu-system-ppc64 -S -display none -M sam460ex -drive if=pflash,format=raw,file=eins.img
    qemu-system-ppc64: Initialization of device cfi.pflash02 failed: failed to read the initial flash content

We happily accept oversized images, ignoring their tail.  Throwing
away parts of firmware that way is pretty much certain to end in an
even more enigmatic failure to boot.

Require the backend's size to match the device's size exactly.  Report
mismatch like this:

    qemu-system-ppc64: Initialization of device cfi.pflash01 failed: device requires 1048576 bytes, block backend provides 512 bytes

Improve the error for actual read failures to "can't read block
backend".

To avoid duplicating even more code between the two pflash device
models, do all that in new helper blk_check_size_and_read_all().

The error reporting can still be confusing.  For instance:

    qemu-system-ppc64 -S -display none -M taihu -drive if=pflash,format=raw,file=eins.img  -drive if=pflash,unit=1,format=raw,file=zwei.img
    qemu-system-ppc64: Initialization of device cfi.pflash02 failed: device requires 2097152 bytes, block backend provides 512 bytes

Leaves the user guessing which of the two -drive is wrong.  Mention
the issue in a TODO comment.

Suggested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190319163551.32499-2-armbru@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
2019-03-26 08:16:24 +01:00

167 lines
4.9 KiB
C

/*
* Common code for block device models
*
* Copyright (C) 2012 Red Hat, Inc.
*
* This work is licensed under the terms of the GNU GPL, version 2 or
* later. See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "sysemu/blockdev.h"
#include "sysemu/block-backend.h"
#include "hw/block/block.h"
#include "qapi/error.h"
#include "qapi/qapi-types-block.h"
/*
* Read the entire contents of @blk into @buf.
* @blk's contents must be @size bytes, and @size must be at most
* BDRV_REQUEST_MAX_BYTES.
* On success, return true.
* On failure, store an error through @errp and return false.
* Note that the error messages do not identify the block backend.
* TODO Since callers don't either, this can result in confusing
* errors.
* This function not intended for actual block devices, which read on
* demand. It's for things like memory devices that (ab)use a block
* backend to provide persistence.
*/
bool blk_check_size_and_read_all(BlockBackend *blk, void *buf, hwaddr size,
Error **errp)
{
int64_t blk_len;
int ret;
blk_len = blk_getlength(blk);
if (blk_len < 0) {
error_setg_errno(errp, -blk_len,
"can't get size of block backend");
return false;
}
if (blk_len != size) {
error_setg(errp, "device requires %" HWADDR_PRIu " bytes, "
"block backend provides %" PRIu64 " bytes",
size, blk_len);
return false;
}
/*
* We could loop for @size > BDRV_REQUEST_MAX_BYTES, but if we
* ever get to the point we want to read *gigabytes* here, we
* should probably rework the device to be more like an actual
* block device and read only on demand.
*/
assert(size <= BDRV_REQUEST_MAX_BYTES);
ret = blk_pread(blk, 0, buf, size);
if (ret < 0) {
error_setg_errno(errp, -ret, "can't read block backend");
return false;
}
return true;
}
void blkconf_blocksizes(BlockConf *conf)
{
BlockBackend *blk = conf->blk;
BlockSizes blocksizes;
int backend_ret;
backend_ret = blk_probe_blocksizes(blk, &blocksizes);
/* fill in detected values if they are not defined via qemu command line */
if (!conf->physical_block_size) {
if (!backend_ret) {
conf->physical_block_size = blocksizes.phys;
} else {
conf->physical_block_size = BDRV_SECTOR_SIZE;
}
}
if (!conf->logical_block_size) {
if (!backend_ret) {
conf->logical_block_size = blocksizes.log;
} else {
conf->logical_block_size = BDRV_SECTOR_SIZE;
}
}
}
bool blkconf_apply_backend_options(BlockConf *conf, bool readonly,
bool resizable, Error **errp)
{
BlockBackend *blk = conf->blk;
BlockdevOnError rerror, werror;
uint64_t perm, shared_perm;
bool wce;
int ret;
perm = BLK_PERM_CONSISTENT_READ;
if (!readonly) {
perm |= BLK_PERM_WRITE;
}
shared_perm = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
BLK_PERM_GRAPH_MOD;
if (resizable) {
shared_perm |= BLK_PERM_RESIZE;
}
if (conf->share_rw) {
shared_perm |= BLK_PERM_WRITE;
}
ret = blk_set_perm(blk, perm, shared_perm, errp);
if (ret < 0) {
return false;
}
switch (conf->wce) {
case ON_OFF_AUTO_ON: wce = true; break;
case ON_OFF_AUTO_OFF: wce = false; break;
case ON_OFF_AUTO_AUTO: wce = blk_enable_write_cache(blk); break;
default:
abort();
}
rerror = conf->rerror;
if (rerror == BLOCKDEV_ON_ERROR_AUTO) {
rerror = blk_get_on_error(blk, true);
}
werror = conf->werror;
if (werror == BLOCKDEV_ON_ERROR_AUTO) {
werror = blk_get_on_error(blk, false);
}
blk_set_enable_write_cache(blk, wce);
blk_set_on_error(blk, rerror, werror);
return true;
}
bool blkconf_geometry(BlockConf *conf, int *ptrans,
unsigned cyls_max, unsigned heads_max, unsigned secs_max,
Error **errp)
{
if (!conf->cyls && !conf->heads && !conf->secs) {
hd_geometry_guess(conf->blk,
&conf->cyls, &conf->heads, &conf->secs,
ptrans);
} else if (ptrans && *ptrans == BIOS_ATA_TRANSLATION_AUTO) {
*ptrans = hd_bios_chs_auto_trans(conf->cyls, conf->heads, conf->secs);
}
if (conf->cyls || conf->heads || conf->secs) {
if (conf->cyls < 1 || conf->cyls > cyls_max) {
error_setg(errp, "cyls must be between 1 and %u", cyls_max);
return false;
}
if (conf->heads < 1 || conf->heads > heads_max) {
error_setg(errp, "heads must be between 1 and %u", heads_max);
return false;
}
if (conf->secs < 1 || conf->secs > secs_max) {
error_setg(errp, "secs must be between 1 and %u", secs_max);
return false;
}
}
return true;
}