We discuss the existing and new hardware virtualization features. First, we review the existing hardware features that are not used by Xen today, showing examples for use cases. 1) For example, The "descriptor-table exiting" should be useful for the guest kernels or security agent to enhance security features. 2) The VMX-preemption timer allows the hypervisor to preempt guest VM execution after a specified amount of time, which is useful to implement fair scheduling. The hardware can save the timer value on each successive VMexit, after setting the initial VM quantum. 3) VMFUNC is an operation provided by the processor that can be invoked from VMX non-root operation without a VM exit. Today, EPTP switching is available, and we discuss how we can use the feature. Second, we talk about new hardware features, especially for interrupt optimizations.
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