On 2026-01-08 02:33 PM, Jason Gunthorpe wrote:
On Thu, Jan 08, 2026 at 10:24:19AM -0800, David Matlack wrote:
Oh, I was thinking about a compatability only flow only in the type 1 emulation that internally magically converts a VMA to a dmabuf, but I haven't written anything.. It is a bit tricky and the type 1 emulation has not been as popular as I expected??
In part because of this gap, I'd guess. Thanks,
Lack of huge mappings in the IOMMU when using VFIO_TYPE1_IOMMU is another gap I'm aware of. vfio_dma_mapping_test.vfio_type1_iommu_anonymous_hugetlb_1gb.dma_map_unmap fails when IOMMUFD_VFIO_CONTAINER is enabled.
What is this? I'm not aware of it..
It's one of the test cases within tools/testing/selftests/vfio/vfio_dma_mapping_test.c.
Here's the output when running with CONFIG_IOMMUFD_VFIO_CONTAINER=y:
# RUN vfio_dma_mapping_test.vfio_type1_iommu_anonymous_hugetlb_1gb.dma_map_unmap ... Mapped HVA 0x7f0480000000 (size 0x40000000) at IOVA 0x0 Searching for IOVA 0x0 in /sys/kernel/debug/iommu/intel/0000:6a:01.0/domain_translation_struct Found IOMMU mappings for IOVA 0x0: PGD: 0x0000000203475027 P4D: 0x0000000203476027 PUD: 0x0000000203477027 PMD: 0x00000001e7562027 PTE: 0x00000041c0000067 # tools/testing/selftests/vfio/vfio_dma_mapping_test.c:188:dma_map_unmap:Expected 0 (0) == mapping.pte (282394099815) # dma_map_unmap: Test terminated by assertion # FAIL vfio_dma_mapping_test.vfio_type1_iommu_anonymous_hugetlb_1gb.dma_map_unmap