PowerShell: Get Hyper-V Host Name from Inside Guest VM

$guestVMName="SOMENAME"

function getHyperVHostname{
        param([string]$guestVMName=$env:computername)
        $hive = [Microsoft.Win32.RegistryHive]::LocalMachine;
        $keyPath = 'SOFTWARE\Microsoft\Virtual Machine\Guest\Parameters';
        $value = 'HostName';
        $reg = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey($hive, $guestVMName);
        $key = $reg.OpenSubKey($keyPath);
        return $key.GetValue($value) ;
    }

getHyperVHostname -guestVmName $guestVmName