| Message ID | 1404926602-11494-1-git-send-email-kwolf@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 07/09/2014 11:23 AM, Kevin Wolf wrote: > 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> > --- > dma-helpers.c | 4 ++++ > include/qemu-common.h | 1 + > util/iov.c | 13 +++++++++++++ > 3 files changed, 18 insertions(+) > Reviewed-by: Eric Blake <eblake@redhat.com>
Il 09/07/2014 19:23, Kevin Wolf ha scritto: > 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> > --- > dma-helpers.c | 4 ++++ > include/qemu-common.h | 1 + > util/iov.c | 13 +++++++++++++ > 3 files changed, 18 insertions(+) > > diff --git a/dma-helpers.c b/dma-helpers.c > index 53cbe92..499b52b 100644 > --- a/dma-helpers.c > +++ b/dma-helpers.c > @@ -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); > + } This is right for read/write, but not for discard. Also, it is wrong if you got a misaligned request that straddles a page boundary, and the second half is from a MMIO device. Do you think this works: - add an alignment argument to dma_bdrv_io, and use it instead of 0 in the "if (dbs->iov.size == 0)" conditional - only do the qemu_iovec_discard_back if the SG list has been processed entirely. Paolo > dbs->acb = dbs->io_func(dbs->bs, dbs->sector_num, &dbs->iov, > dbs->iov.size / 512, dma_bdrv_cb, dbs); > assert(dbs->acb); > diff --git a/include/qemu-common.h b/include/qemu-common.h > index ae76197..6ef8282 100644 > --- a/include/qemu-common.h > +++ b/include/qemu-common.h > @@ -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); > > diff --git a/util/iov.c b/util/iov.c > index 2b4f46d..24566c8 100644 > --- a/util/iov.c > +++ b/util/iov.c > @@ -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; > +} >
diff --git a/dma-helpers.c b/dma-helpers.c index 53cbe92..499b52b 100644 --- a/dma-helpers.c +++ b/dma-helpers.c @@ -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); diff --git a/include/qemu-common.h b/include/qemu-common.h index ae76197..6ef8282 100644 --- a/include/qemu-common.h +++ b/include/qemu-common.h @@ -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); diff --git a/util/iov.c b/util/iov.c index 2b4f46d..24566c8 100644 --- a/util/iov.c +++ b/util/iov.c @@ -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; +}
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> --- dma-helpers.c | 4 ++++ include/qemu-common.h | 1 + util/iov.c | 13 +++++++++++++ 3 files changed, 18 insertions(+)