KVM_MMU_CR4_ROLE_BITS
.cr4 = kvm_read_cr4_bits(vcpu, KVM_MMU_CR4_ROLE_BITS),
BUILD_BUG_ON((KVM_MMU_CR4_ROLE_BITS & KVM_POSSIBLE_CR4_GUEST_BITS));
if ((cr4 ^ old_cr4) & KVM_MMU_CR4_ROLE_BITS)