ARM-on-ARM: Leveraging Virtualization Extensions for Fast Virtual Platforms

Virtual Platforms (VPs) are an essential enabling technology in the System-on-a-Chip (SoC) development cycle. They are used for early software development and hardware/soft- ware codesign. However, since virtual prototyping is limited by simulation performance, improving the simulation speed of VPs has been an active research topic for years. Different strategies have been proposed, such as fast instruction set simulation using Dynamic Binary Translation (DBT). But even fast simulators do not reach native execution speed. They do however allow executing rich Operating System (OS) kernels, which is typically infeasible when another OS is already running.Executing multiple OSs on shared physical hardware is typically accomplished by using virtualization, which has a long history on x86 hardware. It enables encapsulated, native code execution on the host processor and has been extensively used in data centers, where many users share hardware resources. When it comes to embedded systems, virtualization has been made available recently. For ARM processors, virtualization was introduced with the ARM Virtualization Extensions for the ARMv7 architecture. Since virtualization allows native guest code execution, near-native execution speeds can be reached.In this work we present a VP containing a novel ARMv8 SystemC Transaction Level Modeling 2.0 (TLM) compatible processor model. The model leverages the ARM Virtualization Extensions (VE) via the Linux Kernel-based Virtual Machine (KVM) to execute the target software natively on an ARMv8 host. To enable the integration of the processor model into a loosely-timed VP, we developed an accurate instruction counting mechanism using the ARM Performance Monitors Extension (PMU). The requirements for integrating the processor model into a VP and the integration process are detailed in this work.Our evaluations show that speedups of up to 2.57x over state-of-the-art DBT-based simulator can be achieved using our processor model on ARMv8 hardware.