Intel Processor Trace is a hardware feature that recording information about software execution with minimal impact to system execution. Existing hardware is unfriendly to enable Intel PT in guest because the implementation of shadow ToPA is very complex. Intel PT VMX improvements will treat PT output addresses as Guest Physical Addresses (GPAs) and translate them using EPT that serves to simplify the process of Intel PT virtualization for using by a guest software. We have submitted a patch set to enable Intel PT in XEN HVM guest for collecting hardware behavior, backwards debugging for GDB and so on. We also plan to implement system mode for tracing XEN hypervisor and guest's behavior if necessary.
