Preserving IOMMU States During Kexec Reboot for Hypervisor Live Updates

Explore a software-based solution for preserving IOMMU states during kexec reboot in cloud hypervisors. Learn about the challenges of live-updating hosts while minimizing guest downtime, focusing on KVM networking complexities. Discover how carefully managing DRAM pages can create stable IOMMU mapping tables, enabling uninterrupted passthrough device IO activity during kernel live-updates. Examine the technical approach, proof of concept, open questions, and future plans for this innovative method. Delve into topics such as live-migration, vfio-pci integration, and the intricacies of pinning guest RAM pages and IOMMU DMAR tables.

Introduction
Live-migration
Live-update: challenges
Live-update: migrate to file
vfio-pci quick review
Quick recap
Zooming into cpr reboot
Fix: Preserving the state
Pinning guest ram pages
Pinning IOMMU DMAR tables
vfio-pci integration
PoC: design and configuration
PoC: live-update procedure