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_VADDR for VFIO_IOMMU_UNMAP_DMA - VFIO_DMA_MAP_FLAG_VADDR flag for VFIO_IOMMU_MAP_DMA - VFIO_UPDATE_VADDR for VFIO_CHECK_EXTENSION - VFIO_DMA_UNMAP_FLAG_ALL for VFIO_IOMMU_UNMAP_DMA - VFIO_UNMAP_ALL for VFIO_CHECK_EXTENSION Unmap-vaddr invalidates the host virtual address in an iova range and blocks vfio translation of host virtual addresses, but DMA to already-mapped pages continues. Map-vaddr updates the base VA and resumes translation. The implementation supports iommu type1 and mediated devices. Unmap-all allows all ranges to be unmapped or invalidated in a single ioctl, which simplifies userland code. 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 blocks vfio VA translation, exec's its new self, mmap's the memory object(s) underlying vfio object, updates the VA, and unblocks translation. For a working example that uses these new interfaces, see the QEMU patch series "[PATCH V2] Live Update" at https://lore.kernel.org/qemu-devel/1609861330-129855-1-git-send-email-steven.sistare@xxxxxxxxxx Patches 1-3 define and implement the flag to unmap all ranges. Patches 4-6 define and implement the flags to update vaddr. Patches 7-9 add blocking to complete the implementation. Changes in V2: - define a flag for unmap all instead of special range values - define the VFIO_UNMAP_ALL extension - forbid the combination of unmap-all and get-dirty-bitmap - unwind in unmap on vaddr error - add a new function to find first dma in a range instead of modifying an existing function - change names of update flags - fix concurrency bugs due to iommu lock being dropped - call down from from vfio to a new backend interface instead of up from driver to detect container close - use wait/wake instead of sleep and polling - refine the uapi specification - split patches into vfio vs type1 Changes in V3: - add vaddr_invalid_count to fix pin_pages race with unmap - refactor the wait helper functions - traverse dma entries more efficiently in unmap - check unmap flag conflicts more explicitly - rename some local variables and functions Steve Sistare (9): vfio: option to unmap all vfio/type1: unmap cleanup vfio/type1: implement unmap all vfio: interfaces to update vaddr vfio/type1: massage unmap iteration vfio/type1: implement interfaces to update vaddr vfio: iommu driver notify callback vfio/type1: implement notify callback vfio/type1: block on invalid vaddr drivers/vfio/vfio.c | 5 + drivers/vfio/vfio_iommu_type1.c | 251 +++++++++++++++++++++++++++++++++++----- include/linux/vfio.h | 5 + include/uapi/linux/vfio.h | 27 +++++ 4 files changed, 256 insertions(+), 32 deletions(-) -- 1.8.3.1
