Starting support for Hyper-V nested virtualization

plugins/providers/hyperv/action/import.rb

@@ -21,10 +21,12 @@ module VagrantPlugins
           differencing_disk = env[:machine].provider_config.differencing_disk
           auto_start_action = env[:machine].provider_config.auto_start_action
           auto_stop_action = env[:machine].provider_config.auto_stop_action
+          enable_virtualization_extensions = env[:machine].provider_config.enable_virtualization_extensions
 
           env[:ui].output("Configured Dynamic memory allocation, maxmemory is #{maxmemory}") if maxmemory
           env[:ui].output("Configured startup memory is #{memory}") if memory
           env[:ui].output("Configured cpus number is #{cpus}") if cpus
+          env[:ui].output("Configured enable virtualization extensions is #{enable_virtualization_extensions}") if enable_virtualization_extensions
           env[:ui].output("Configured vmname is #{vmname}") if vmname
           env[:ui].output("Configured differencing disk instead of cloning") if differencing_disk
           env[:ui].output("Configured automatic start action is #{auto_start_action}") if auto_start_action
@@ -145,6 +147,7 @@ module VagrantPlugins
           options[:auto_start_action] = auto_start_action if auto_start_action
           options[:auto_stop_action] = auto_stop_action if auto_stop_action
           options[:differencing_disk] = differencing_disk if differencing_disk
+          options[:enable_virtualization_extensions] = enable_virtualization_extensions if enable_virtualization_extensions
 
           env[:ui].detail("Creating and registering the VM...")
           server = env[:machine].provider.driver.import(options)

plugins/providers/hyperv/config.rb

@@ -26,6 +26,7 @@ module VagrantPlugins
         @differencing_disk = UNSET_VALUE
         @auto_start_action = UNSET_VALUE
         @auto_stop_action = UNSET_VALUE
+        @enable_virtualization_extensions = UNSET_VALUE
       end
 
       def finalize!
@@ -41,6 +42,7 @@ module VagrantPlugins
         @differencing_disk = false if @differencing_disk == UNSET_VALUE
         @auto_start_action = nil if @auto_start_action == UNSET_VALUE
         @auto_stop_action = nil if @auto_stop_action == UNSET_VALUE
+        @enable_virtualization_extensions = false if @enable_virtualization_extensions == UNSET_VALUE # TODO will this work?
       end
 
       def validate(machine)

plugins/providers/hyperv/scripts/import_vm_xml.ps1

@@ -10,7 +10,8 @@ Param(
     [string]$cpus=$null,
     [string]$vmname=$null,
     [string]$auto_start_action=$null,
-    [string]$auto_stop_action=$null
+    [string]$auto_stop_action=$null,
+    [bool]$enable_virtualization_extensions=$False
 )
 
 # Include the following modules
@@ -170,6 +171,11 @@ if ($generation -ne 1) {
     }
 }
 
+# Enable nested virtualization if configured
+if ($enable_virtualization_extensions) {
+    Set-VMProcessor -VM $vm -ExposeVirtualizationExtensions $true
+}
+
 # A regular expression pattern to pull the number from controllers
 [regex]$rx="\d"