VMCS12 is used to keep the authoritative state during nested state migration. In case 'need_vmcs12_to_shadow_sync' flag is set, we're in between L2->L1 vmexit and L1 guest run when actual sync to enlightened (or shadow) VMCS happens. Nested state, however, has no flag for 'need_vmcs12_to_shadow_sync' so vmx_set_nested_state()-> set_current_vmptr() always sets it. Enlightened vmptrld path, however, doesn't have the quirk so some VMCS12 changes may not get properly reflected to eVMCS and L1 will see an incorrect state. Note, during L2 execution or when need_vmcs12_to_shadow_sync is not set the change is effectively a nop: in the former case all changes will get reflected during the first L2->L1 vmexit and in the later case VMCS12 and eVMCS are already in sync (thanks to copy_enlightened_to_vmcs12() in vmx_get_nested_state()). Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> --- arch/x86/kvm/vmx/nested.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 1661e2e19560..0a422c6091dc 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -3135,6 +3135,12 @@ static bool nested_get_evmcs_page(struct kvm_vcpu *vcpu) if (evmptrld_status == EVMPTRLD_VMFAIL || evmptrld_status == EVMPTRLD_ERROR) return false; + + /* + * Post migration VMCS12 always provides the most actual + * information, copy it to eVMCS upon entry. + */ + vmx->nested.need_vmcs12_to_shadow_sync = true; } return true; -- 2.30.2
