On Fri, Apr 21, 2023 at 11:32:17PM +0800, Chao Gao wrote: >>For case 2) I _think_ we need new code to check both VMCS12's HOST_CR3 and >>GUEST_CR3 against active control bits. The key code path is > >... > >> >> nested_vmx_run() -> >> -> nested_vmx_check_host_state() >> -> nested_vmx_enter_non_root_mode() >> -> prepare_vmcs02_early() >> -> prepare_vmcs02() >> >>Since nested_vmx_load_cr3() is used in both VMENTER using VMCS12's HOST_CR3 >>(VMEXIT to L1) and GUEST_CR3 (VMENTER to L2), and it currently already checks >>kvm_vcpu_is_illegal_gpa(vcpu, cr3), changing it to additionally check guest CR3 >>active control bits seems just enough. > >IMO, current KVM relies on hardware to do consistency check on the GUEST_CR3 >during VM entry. Please disregard my remark on the consistency check on GUEST_CR3. I just took a closer look at the code. It is indeed done by KVM in nested_vmx_load_cr3(). Sorry for the noise.
