Hi, here is the next version of this patch-set. Previous versions can be found here: V1: https://lore.kernel.org/lkml/20190110134433.15672-1-joro@xxxxxxxxxx/ V2: https://lore.kernel.org/lkml/20190115132257.6426-1-joro@xxxxxxxxxx/ V3: https://lore.kernel.org/lkml/20190123163049.24863-1-joro@xxxxxxxxxx/ V4: https://lore.kernel.org/lkml/20190129084342.26030-1-joro@xxxxxxxxxx/ The problem solved here is a limitation of the SWIOTLB implementation, which does not support allocations larger than 256kb. When the virtio-blk driver tries to read/write a block larger than that, the allocation of the dma-handle fails and an IO error is reported. Changes to v4 are: - Added Reviewed-by tags from Christoph - Added missing EXPORT_SYMBOL(_GPL) lines Please review. Thanks, Joerg Joerg Roedel (5): swiotlb: Introduce swiotlb_max_mapping_size() swiotlb: Add is_swiotlb_active() function dma: Introduce dma_max_mapping_size() virtio: Introduce virtio_max_dma_size() virtio-blk: Consider virtio_max_dma_size() for maximum segment size Documentation/DMA-API.txt | 8 ++++++++ drivers/block/virtio_blk.c | 10 ++++++---- drivers/virtio/virtio_ring.c | 11 +++++++++++ include/linux/dma-mapping.h | 16 ++++++++++++++++ include/linux/swiotlb.h | 11 +++++++++++ include/linux/virtio.h | 2 ++ kernel/dma/direct.c | 12 ++++++++++++ kernel/dma/swiotlb.c | 14 ++++++++++++++ 8 files changed, 80 insertions(+), 4 deletions(-) -- 2.17.1