KVM: VMX: always require WB memory type for EPT

We already always set that type but don't check if it is supported. Also
for nVMX, we only support WB for now. Let's just require it.
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

arch/x86/kvm/vmx.c

@@ -1200,6 +1200,11 @@ static inline bool cpu_has_vmx_ept_4levels(void)
 	return vmx_capability.ept & VMX_EPT_PAGE_WALK_4_BIT;
 }
 
+static inline bool cpu_has_vmx_ept_mt_wb(void)
+{
+	return vmx_capability.ept & VMX_EPTP_WB_BIT;
+}
+
 static inline bool cpu_has_vmx_ept_ad_bits(void)
 {
 	return vmx_capability.ept & VMX_EPT_AD_BIT;
@@ -4300,7 +4305,6 @@ static u64 construct_eptp(struct kvm_vcpu *vcpu, unsigned long root_hpa)
 {
 	u64 eptp = VMX_EPTP_MT_WB | VMX_EPTP_PWL_4;
 
-	/* TODO write the value reading from MSR */
 	if (enable_ept_ad_bits &&
 	    (!is_guest_mode(vcpu) || nested_ept_ad_enabled(vcpu)))
 		eptp |= VMX_EPTP_AD_ENABLE_BIT;
@@ -6635,7 +6639,8 @@ static __init int hardware_setup(void)
 		init_vmcs_shadow_fields();
 
 	if (!cpu_has_vmx_ept() ||
-	    !cpu_has_vmx_ept_4levels()) {
+	    !cpu_has_vmx_ept_4levels() ||
+	    !cpu_has_vmx_ept_mt_wb()) {
 		enable_ept = 0;
 		enable_unrestricted_guest = 0;
 		enable_ept_ad_bits = 0;