kvm: nVMX: Validate the virtual-APIC address on nested VM-entry

According to the SDM, if the "use TPR shadow" VM-execution control is
1, bits 11:0 of the virtual-APIC address must be 0 and the address
should set any bits beyond the processor's physical-address width.
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

@@ -9993,6 +9993,18 @@ static int nested_vmx_check_msr_bitmap_controls(struct kvm_vcpu *vcpu,
 	return 0;
 }
 
+static int nested_vmx_check_tpr_shadow_controls(struct kvm_vcpu *vcpu,
+						struct vmcs12 *vmcs12)
+{
+	if (!nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW))
+		return 0;
+
+	if (!page_address_valid(vcpu, vmcs12->virtual_apic_page_addr))
+		return -EINVAL;
+
+	return 0;
+}
+
 /*
  * Merge L0's and L1's MSR bitmap, return false to indicate that
  * we do not use the hardware.
@@ -10680,6 +10692,9 @@ static int check_vmentry_prereqs(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 	if (nested_vmx_check_msr_bitmap_controls(vcpu, vmcs12))
 		return VMXERR_ENTRY_INVALID_CONTROL_FIELD;
 
+	if (nested_vmx_check_tpr_shadow_controls(vcpu, vmcs12))
+		return VMXERR_ENTRY_INVALID_CONTROL_FIELD;
+
 	if (nested_vmx_check_apicv_controls(vcpu, vmcs12))
 		return VMXERR_ENTRY_INVALID_CONTROL_FIELD;