Research And Implementation Of Hardware-assisted I/O Virtualization For Many-Core Platform

Recently, Virtualization Technology appeals the common interests of both the industry and academy due to its obvious advantages. However, it also encounters the problem of serious performance overheads, especially for the I/O-intensive workload; therefore it is an urgent task to solve the performance overheads caused by I/O virtualization, particularly for the virtualization systems based on many-core processor. The hardware-assisted I/O virtualization Technology, which enables the Guest OSs directly and safely accesses the device without the VMM software's interference, is considered to be one of the best solutions to the overheads problem.This paper presents a design of hardware-assisted I/O virtualization for many-core platform, which is based on the PCIE interface layer for the practical project demands. To reach the requirements of frequent I/O access and high reliability in the virtualization systems based on the many-core processor, this design make special efforts on the DMA remapping, interrupt remapping and PIO which is for the core to configurate the devices'control and state registers. For DMA remapping, it add the I/O space mapping function to ensure isolation between different domains. It speed up the address translation procedure between guest virtual address and host physical address through optimizing the structure of I/O Translate Lookaside Buffer and prefetching technique. For interrupt remapping, this design integrate interrupt remapping table on the chip to accelerate the remapping procedure, in addition, it adopt an asynchronous event queue mechanism to handle the MSI interrupt,a dominant I/O interrupt type, which could accelerate the speed of handling this kind interrupts and reduce the performance impact on the cores. For PIO, this design uses a tactics which combines the tag assignment with score board mechanism, to improve the reliability and remap the PIO completion data.Since there are so many I/O accesses towards the shared device in the virtualization system based on many-core platform and they are not applicable to the design mentioned above, this paper addresses a solution named Hardware-assisted Self-Virtualization, which enables multiple guest OS directly access the device. Compared with existing Self-Virtualization Technology, my solution has such advantages as low hardware cost and flexible configuration.