kernel: KVM: nVMX: missing consistency checks for CR0 and CR4

A flaw was found in the KVM's Intel nested virtualization feature nVMX. The effective values of the guest CR0 and CR4 registers could differ from those included in the VMCS12. In rare circumstances i.e., kvmintel module loaded with parameters nested=1 and ept=0 this could allow a malicious guest ...