VCPU_EXREG_CR4
!kvm_register_is_available(vcpu, VCPU_EXREG_CR4))
kvm_x86_call(cache_reg)(vcpu, VCPU_EXREG_CR4);
case VCPU_EXREG_CR4:
kvm_register_mark_available(vcpu, VCPU_EXREG_CR4);
(1 << VCPU_EXREG_CR4) | \