On x86, when assigning VFIO-PCI devices protected with virtio-iommu we encounter the case where the guest tries to map IOVAs beyond 48b whereas the physical VTD IOMMU only supports 48b. This ends up with VFIO_MAP_DMA failures at qemu level because at kernel level, vfio_iommu_iova_dma_valid() check returns false on vfio_map_do_map().
This is due to the fact the virtio-iommu currently unconditionally exposes an IOVA range of 64b through its config input range fields. This series removes this assumption by retrieving the usable IOVA regions through the VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE UAPI when a VFIO device is attached. This info is communicated to the virtio-iommu memory region, transformed into the inversed info, ie. the host reserved IOVA regions. Then those latter are combined with the reserved IOVA regions set though the virtio-iommu reserved-regions property. That way, the guest virtio-iommu driver, unchanged, is able to probe the whole set of reserved regions and prevent any IOVA belonging to those ranges from beeing used, achieving the original goal. Best Regards Eric This series can be found at: https://github.com/eauger/qemu/tree/virtio-iommu_geometry_v2 History: v1 -> v2: - Remove "[PATCH 12/13] virtio-iommu: Resize memory region according to the max iova info" which causes way too much trouble: trigger a coredump in vhost, causes duplication of IOMMU notifiers causing EEXIST vfio_dma_map errors, ... This looks like a bad usage of the memory API so I prefer removing this from this series. So I was also obliged to remove the vfio_find_hostwin() check in the case of an IOMMU MR. - Let range_inverse_array() take low/high args instead of hardcoding 0, UINT64_MAX which both complexifies the algo and the tests. - Move range function description in header. - Check that if set_iova_ranges is called several times, new resv regions are included in previous ones Eric Auger (12): memory: Let ReservedRegion use Range memory: Introduce memory_region_iommu_set_iova_ranges vfio: Collect container iova range info virtio-iommu: Rename reserved_regions into prop_resv_regions virtio-iommu: Introduce per IOMMUDevice reserved regions range: Introduce range_inverse_array() virtio-iommu: Implement set_iova_ranges() callback range: Make range_compare() public util/reserved-region: Add new ReservedRegion helpers virtio-iommu: Consolidate host reserved regions and property set ones test: Add some tests for range and resv-mem helpers vfio: Remove 64-bit IOVA address space assumption include/exec/memory.h | 30 +++- include/hw/vfio/vfio-common.h | 2 + include/hw/virtio/virtio-iommu.h | 7 +- include/qemu/range.h | 14 ++ include/qemu/reserved-region.h | 32 ++++ hw/core/qdev-properties-system.c | 9 +- hw/vfio/common.c | 70 +++++++-- hw/virtio/virtio-iommu-pci.c | 8 +- hw/virtio/virtio-iommu.c | 110 ++++++++++++-- softmmu/memory.c | 15 ++ tests/unit/test-resv-mem.c | 251 +++++++++++++++++++++++++++++++ util/range.c | 51 ++++++- util/reserved-region.c | 94 ++++++++++++ hw/virtio/trace-events | 1 + tests/unit/meson.build | 1 + util/meson.build | 1 + 16 files changed, 655 insertions(+), 41 deletions(-) create mode 100644 include/qemu/reserved-region.h create mode 100644 tests/unit/test-resv-mem.c create mode 100644 util/reserved-region.c -- 2.41.0
