IOMMU State Preservation for Kernel Liveupdate

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" summary

Kernel liveupdate preserves full IOMMU state across kexec by saving IOMMUFDs, domain and device context into the FLB so DMA mappings survive early boot. It uses a generic page table walker to collect page-table pages and marks HPTs for preservation, integrates with VFIO device preservation, and records pass ID and domain allocations (pass ID table not in RFC v1). Restore recreates domains, reattaches devices, then swaps the immutable restored HPT for a new HPT. Proof of concept works on ARM; Intel needs hitless replace work.

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" chapters (7)

1. 0:00Introduction to IOMMU preservation
2. 1:49Preservation process overview
3. 3:15Device-specific state preservation
4. 5:22Restoration in next kernel
5. 8:55Caveats and challenges
6. 11:25Hitless domain replacement
7. 13:34Interaction with VMM features