VFIO currently exposes the usable IOVA regions through the VFIO_IOMMU_GET_INFO ioctl / VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE capability. However it fails to take into account the dma_mask of the devices within the container. The top limit currently is defined by the iommu aperture.
So, for instance, if the IOMMU supports up to 48bits, it may give the impression the max IOVA is 48b while a device may have a dma_mask of 42b. So this API cannot really be used to compute the max usable IOVA. This patch removes the IOVA region beyond the dma_mask's. As we start to expose this reserved region in the sysfs file /sys/kernel/iommu_groups/<n>/reserved_regions, we also need to handle the IOVA range beyond the IOMMU aperture to handle the case where the dma_mask would have a higher number of bits than the iommu max input address. This is a change to the ABI as this reserved region was not yet exposed in sysfs /sys/kernel/iommu_groups/<n>/reserved_regions or through the VFIO ioctl. At VFIO level we increment the version of the VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE capability to advertise that change. Best Regards Eric This series can be found at: https://github.com/eauger/qemu/tree/dma_mask_rfc Eric Auger (3): iommu: Fix merging in iommu_insert_resv_region iommu: Account for dma_mask and iommu aperture in IOVA reserved regions vfio/type1: Increase the version of VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE .../ABI/testing/sysfs-kernel-iommu_groups | 7 ++++ drivers/iommu/iommu.c | 41 ++++++++++++++++++- drivers/vfio/vfio_iommu_type1.c | 2 +- 3 files changed, 48 insertions(+), 2 deletions(-) -- 2.21.3 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
