BitLocker support and ability to use already mounted drives

Update-VMGpuPartitionDriver.ps1

@@ -1,52 +1,71 @@
-<# 
+<# 
 If you are opening this file in Powershell ISE you should modify the params section like so...
 Remember: GPU Name must match the name of the GPU you assigned when creating the VM...
 
 Param (
 [string]$VMName = "NameofyourVM",
 [string]$GPUName = "NameofyourGPU",
+[string]$BitLockerKey = "XXXXXX-XXXXXX-XXXXXX-XXXXXX-XXXXXX-XXXXXX-XXXXXX-XXXXXX",
 [string]$Hostname = $ENV:Computername
 )
 
 #>
 
 Param (
-[string]$VMName,
-[string]$GPUName,
-[string]$Hostname = $ENV:Computername
+    [string]$VMName,
+    [string]$GPUName,
+    [string]$BitLockerKey,
+    [string]$Hostname = $ENV:Computername
 )
 
+$ErrorActionPreference = "Stop"
+
 Import-Module $PSSCriptRoot\Add-VMGpuPartitionAdapterFiles.psm1
 
 $VM = Get-VM -VMName $VMName
 $VHD = Get-VHD -VMId $VM.VMId
 
 If ($VM.state -eq "Running") {
-    [bool]$state_was_running = $true
-    }
+    [bool]$state_was_running = $True
+}
 
-if ($VM.state -ne "Off"){
+if ($VM.state -ne "Off") {
     "Attemping to shutdown VM..."
     Stop-VM -Name $VMName -Force
-    } 
+    $VHD = Get-VHD -VMId $VM.VMId
+} 
 
 While ($VM.State -ne "Off") {
     Start-Sleep -s 3
     "Waiting for VM to shutdown - make sure there are no unsaved documents..."
-    }
+}
 
-"Mounting Drive..."
-$DriveLetter = (Mount-VHD -Path $VHD.Path -PassThru | Get-Disk | Get-Partition | Get-Volume | Where-Object {$_.DriveLetter} | ForEach-Object DriveLetter)
+if ($VHD.Attached -eq $False) {
+    "Mounting Drive..."
+    $DriveLetter = (Mount-VHD -Path $VHD.Path -PassThru | Get-Disk | Get-Partition | Get-Volume | Where-Object { $_.DriveLetter } | ForEach-Object DriveLetter)
+}
+else {
+    $DriveLetter = ($VHD | Get-Disk | Get-Partition | Get-Volume | Where-Object { $_.DriveLetter } | ForEach-Object DriveLetter)
+    "Using already mounted drive ${DriveLetter}"
+}
+
+$BitLockerStatus = Get-BitLockerVolume $DriveLetter
+if ($BitLockerStatus.LockStatus) {
+    if ([string]::IsNullOrWhiteSpace($BitLockerKey)) {
+        $BitLockerKey = Read-Host "Enter BitLocker Key for drive ${DriveLetter}"
+    }
+    Unlock-BitLocker -MountPoint $DriveLetter -RecoveryPassword $BitLockerKey
+}
 
 "Copying GPU Files - this could take a while..."
 Add-VMGPUPartitionAdapterFiles -hostname $Hostname -DriveLetter $DriveLetter -GPUName $GPUName
 
 "Dismounting Drive..."
 Dismount-VHD -Path $VHD.Path
 
-If ($state_was_running){
+If ($state_was_running) {
     "Previous State was running so starting VM..."
     Start-VM $VMName
-    }
+}
 
 "Done..."