KVM: VMX: Zero the vpid module parameter if vpid is not supported

This allows reading back how the hardware is configured.
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/vmx.c

@@ -1202,6 +1202,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 		      vmx_capability.ept, vmx_capability.vpid);
 	}
 
+	if (!cpu_has_vmx_vpid())
+		enable_vpid = 0;
+
 	min = 0;
 #ifdef CONFIG_X86_64
 	min |= VM_EXIT_HOST_ADDR_SPACE_SIZE;
@@ -2082,7 +2085,7 @@ static void allocate_vpid(struct vcpu_vmx *vmx)
 	int vpid;
 
 	vmx->vpid = 0;
-	if (!enable_vpid || !cpu_has_vmx_vpid())
+	if (!enable_vpid)
 		return;
 	spin_lock(&vmx_vpid_lock);
 	vpid = find_first_zero_bit(vmx_vpid_bitmap, VMX_NR_VPIDS);