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blkio: Respect memory-alignment for bounce buffer allocations

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blkio_alloc_mem_region() requires that the requested buffer size is a
multiple of the memory-alignment property. If it isn't, the allocation
fails with a return value of -EINVAL.

Fix the call in blkio_resize_bounce_pool() to make sure the requested
size is properly aligned.

I observed this problem with vhost-vdpa, which requires page aligned
memory. As the virtio-blk device behind it still had 512 byte blocks, we
got bs->bl.request_alignment = 512, but actually any request that needed
a bounce buffer and was not aligned to 4k would fail without this fix.

Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20240131173140.42398-1-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2024-01-31 18:31:40 +01:00
parent 3089637461
commit 10b2393e5e
1 changed files with 3 additions and 0 deletions
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3
block/blkio.c
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@ -89,6 +89,9 @@ static int blkio_resize_bounce_pool(BDRVBlkioState *s, int64_t bytes)
/* Pad size to reduce frequency of resize calls */
bytes += 128 * 1024;
/* Align the pool size to avoid blkio_alloc_mem_region() failure */
bytes = QEMU_ALIGN_UP(bytes, s->mem_region_alignment);
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
int ret;