Currently, when amd svm or intel vmx is used to run the guest os natively on the chip, a kernel enter and vmenter are needed, and when the guest os executes a trapping instruction, a vmexit and kernel exit is incurred. I would like to know the latest estimate of the cost of VMEnter/VMExit on the Intel or AMD x86 chip and kernel enter/exit on 2.6.x linux. Any paper or presentation on it would be great.