[PATCH v3 0/5] Fixes for dma-iommu swiotlb bounce buffers

From: David Stevens
Date: Tue Aug 10 2021 - 22:44:13 EST

From: David Stevens <stevensd@xxxxxxxxxxxx>

This patch set includes various fixes for dma-iommu's swiotlb bounce
buffers for untrusted devices. There are three fixes for correctness
issues, one performance issue, and one general cleanup.

The min_align_mask issue was found when running fio on an untrusted nvme
device with bs=512. The other issues were found via code inspection, so
I don't have any specific use cases where things were not working, nor
any concrete performance numbers.

v2 -> v3:
- Add new patch to address min_align_mask bug
- Set SKIP_CPU_SYNC flag after syncing in map/unmap
- Properly call arch_sync_dma_for_cpu in iommu_dma_sync_sg_for_cpu

v1 -> v2:
- Split fixes into dedicated patches
- Less invasive changes to fix arch_sync when mapping
- Leave dev_is_untrusted check for strict iommu

David Stevens (5):
dma-iommu: fix sync_sg with swiotlb
dma-iommu: fix arch_sync_dma for map
dma-iommu: add SKIP_CPU_SYNC after syncing
dma-iommu: Check CONFIG_SWIOTLB more broadly
dma-iommu: account for min_align_mask

drivers/iommu/dma-iommu.c | 97 +++++++++++++++++++++------------------
1 file changed, 53 insertions(+), 44 deletions(-)