Xen Paravirtualization Technology Of Virtual Machine Uncertainty Event Record And Replay System

Today computer industry and academia,the security of software systems is one of the focuses of attention.On the one hand,the forward software code analysis can't fully meet the requirements.The reverse event playback technology provides a new method for the software system debugging.On the other hand,host-based monitoring and recording software can no longer meet the needs of security researchers.More representative systems such as ReVirt,ReTrace and ExecRecorder.But they also have their own disadvantages,some are slow and inefficient,some need to modify the client system,and some log storage is not efficient.All these problems are urgently resolved.Virtual machine uncertainty event recording and playback system based on Xen paravirtualization effectively solves these problems.Specifically,the system has the following features: First,the log storage efficiency is relatively high.Using the log data processing integration technology and Xen's own Hypercall Preemption Check technology,there is only one log data file generated,and there is a strict temporal ordering relationship between the log records.System playback requires just need one log file to be read;The second is the use of the shared memory between the Xen and Dom0 cores for data transfer.The number of copies of data during the recording and playback process is very small.The efficiency of the log record transfer is very high,The third is to program the performance counter to determine the precise playback time,The fourth is to modify Xen's own virtual machine scheduler to reduce the impact of other virtual machine operations on playback accuracy.The system described in this paper implements keyboard events and logging and playback.In addition,it leaves an interface for recording and playback of other uncertain events.System testing shows that only about 14% of performance overhead is incurred when the system is turned on.Compared with the existing ReVirt system in the CoVirt project of the University of California,the system has an approximately21% performance increase in event playback.