how can i determining a vm system disk installed on which disk

[renhaoran1994]

i get a vm info so how can i get vm system disk installed on whick disk or device like this

content = si.RetrieveContent()
search_index = content.searchIndex
vm = search_index.FindByUuid(None, uuid, True)
vm.layout.disk
vm.config

i only get the disk key and device info i want get the vm system disk thx for help