Virtual Function Migration with SR-IOV PCIe State Preservation
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Solution Overview
Problem
Migrating virtual machines (VMs) between hosts is a slow and cumbersome process due to the need to deallocate and reallocate virtual functions (VFs) on PCIe cards, which are not part of the VMs, leading to bottlenecks and inefficiencies in network access and storage connectivity.
Innovation Solution
Implementing SR-IOV capable PCIe devices that allow for the configuration of virtual functions (VFs) to be migrated with the VMs, preserving their state and maintaining network and storage connections, enabling quicker and more efficient VM migrations by using software-defined network and NVMe interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If VMs are migrated between hosts by deallocating and reallocating VFs on PCIe cards, then VM migration can be achieved, but the migration process becomes slow and cumbersome due to connection reestablishment requirements
Solution Approach 1:
The patent merges the VM migration process with the VF state preservation and transfer. By capturing the VF state (including PCIe configuration space, BAR regions, and device-specific registers) as part of the VM image and restoring it on the destination host, the VF is effectively moved along with the VM. This eliminates the traditional approach of deallocating VFs on the source host and reallocating them on the destination host, thereby avoiding connection reestablishment delays and significantly improving migration speed.
2Adaptability or versatility
If VFs are deallocated and reallocated during VM migration, then VMs can move between hosts, but network and storage connections must be reestablished causing bottlenecks and inefficiencies
Solution Approach 1:
The patent performs preliminary action by capturing and preserving the VF state (including PCIe configuration space, BAR regions, and device-specific registers) before VM migration. This state data is embedded in the VM image and restored on the destination host before the VM resumes operation. By preparing the VF state in advance and ensuring it is properly restored, the system maintains network and storage connections without requiring reestablishment, thus avoiding bottlenecks and inefficiencies while enabling VM mobility.
3Ease of operation
If traditional VM migration is performed without VF state preservation, then migration can be completed, but the process is cumbersome and requires manual intervention for connection reestablishment
Solution Approach 1:
The patent implements self-service by automating the entire VF state preservation and restoration process. The hypervisor automatically captures the VF state (PCIe configuration space, BAR regions, device-specific registers) when the VM is migrated, embeds it in the VM image, and restores it on the destination host without requiring manual intervention. This automation eliminates the need for operators to manually reestablish network and storage connections, significantly improving ease of operation and reducing connection reestablishment time.
Data Source
AI summary
Virtual functions (VFs) running on SR-IOV (single root IO virtualization) capable PCIe devices can migrate in association with VMs using the VFs. A SR-IOV capable PCIe device installed in a host computer can implement the VFs. A VM running on the host and associated with the VF can use the VF to obtain a service such as network communications or access to a NAS device. Migrating the VF in association with the VM can include halting the VM in a VM state on the host, halting the VF in a PCIe state and then obtaining a PCIe state data, restarting the VF in the PCIe state on a second PCIe device of a second host based on the PCIe state data, and restarting the VM in the VM state on the second host, wherein the VM is configured to use the VF on the second PCIe device.