Comment 6 for bug 1904632

VM Exit is a term in the Intel CPU's Virtualization support (VMX). It means the execution of the guest CPU is interrupted and the execution "jumps" to some function in the hypervisor; the hypervisor analyzes the reason of the VM Exit, and handles the VM exit properly, and then the execution "jumps" back to wherever the guest CPU was interrupted. Here the issue is: when the Level-2 guest CPU's VM Exit happens, somehow the hypervisor messes up the Level-1 guest's 32-bit related state (i.e. the SYSENTER instruction related state), so later when the 32-bit progarm starts to run, the Level-1 guest kernel crashes due to double-fault. The investigation is still ongoing.