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dma-helpers: Fix too long qiov

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If the size of the scatter/gather list isn't a multiple of 512, the
number of sectors for the block layer request is rounded down, resulting
in a qiov that doesn't match the request length. Truncate the qiov to the
new length of the request.

This fixes the IDE qtest case /x86_64/ide/bmdma/short_prdt.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Kevin Wolf 2014-07-09 19:17:30 +02:00
parent 80504dcaa1
commit 58f423fbd5
3 changed files with 18 additions and 0 deletions
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4
dma-helpers.c
View File

@ -170,6 +170,10 @@ static void dma_bdrv_cb(void *opaque, int ret)
return;
}
if (dbs->iov.size & ~BDRV_SECTOR_MASK) {
qemu_iovec_discard_back(&dbs->iov, dbs->iov.size & ~BDRV_SECTOR_MASK);
}
dbs->acb = dbs->io_func(dbs->bs, dbs->sector_num, &dbs->iov,
dbs->iov.size / 512, dma_bdrv_cb, dbs);
assert(dbs->acb);

1
include/qemu-common.h
View File

@ -329,6 +329,7 @@ size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
int fillc, size_t bytes);
ssize_t qemu_iovec_compare(QEMUIOVector *a, QEMUIOVector *b);
void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf);
void qemu_iovec_discard_back(QEMUIOVector *qiov, size_t bytes);
bool buffer_is_zero(const void *buf, size_t len);

13
util/iov.c
View File

@ -550,3 +550,16 @@ size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt,
return total;
}
void qemu_iovec_discard_back(QEMUIOVector *qiov, size_t bytes)
{
size_t total;
unsigned int niov = qiov->niov;
assert(qiov->size >= bytes);
total = iov_discard_back(qiov->iov, &niov, bytes);
assert(total == bytes);
qiov->niov = niov;
qiov->size -= bytes;
}