Add interfaces that allow the underlying memory object of an iova range to be mapped to a new virtual address in the host process: - VFIO_DMA_UNMAP_FLAG_SUSPEND for VFIO_IOMMU_UNMAP_DMA - VFIO_DMA_MAP_FLAG_RESUME flag for VFIO_IOMMU_MAP_DMA - VFIO_SUSPEND extension for VFIO_CHECK_EXTENSION The suspend interface blocks vfio translation of host virtual addresses in a range, but DMA to already-mapped pages continues. The resume interface records the new base VA and resumes translation. The implementation supports iommu type1 and mediated devices. This functionality is necessary for live update, in which a host process such as qemu exec's an updated version of itself, while preserving its guest and vfio devices. The process suspends vfio VA translation, exec's its new self, mmap's the memory object(s) underlying vfio object, and resumes VA translation. For a working example that uses these new interfaces, see the QEMU patch series "[PATCH V2] Live Update". Patch 1 modifies the iova rbtree to allow iteration over ranges with gaps, without deleting each entry. This is required by patch 4. Patch 2 adds an option to unmap all ranges, which simplifies userland code. Patch 3 adds an interface to detect if an iommu_group has a valid container, which patch 5 uses to release a blocked thread if a container is closed. Patch 4 implements the new ioctl's. Patch 5 adds blocking to complete the implementation . Steve Sistare (5): vfio: maintain dma_list order vfio: option to unmap all vfio: detect closed container vfio: VA suspend interface vfio: block during VA suspend drivers/vfio/vfio.c | 12 ++++ drivers/vfio/vfio_iommu_type1.c | 122 ++++++++++++++++++++++++++++++++++------ include/linux/vfio.h | 1 + include/uapi/linux/vfio.h | 19 ++++++- 4 files changed, 135 insertions(+), 19 deletions(-) -- 1.8.3.1
