During address translation on AArch64, we need to access some system registers like TCR_ELx, TTBR_ELx and etc. The access is done via system register instructions. In this article, I will introduce how the instructions are constructed and how it should work in Rust with KVM. System Registers on AArch64 System Register Instructions AArch64 provides 2 instructions to…

This article is a collection of essential knowledge of address translation on AArch64. It doesn’t cover every aspects of the translation. I only focus on the information that is related to the scenario that happens when we use GDB to debug the guest kernel. To enable the GDB support on…

Although appearing in this series, AT instruction is not part of the solution for supporting GDB. As a solution candidate once considered in early stage, using AT instruction soon turned out infeasible for GVA translation. This article is for knowledge sharing only. AT Instruction AT is the instruction on AArch64 for address…

In this article I will continue to explore the way for Cloud Hypervisor to support GDB on Arm64 architecture. After understanding how things should work in a VMM program to enable GDB to debug guest kernel in previous posts, now it’s time to find out what should be done. In…

In this article I will introduce how “GDB remote debugging” is implemented in Cloud Hypervisor. Generally the implementation includes 2 equally important parts: External gdbstub crate Supporting part for various debugging functionalities of Cloud Hypervisor I created a diagram to depict the relationship between all the components involved. The components…

Now, in June 2022, one of the gaps to fill for Arm64 architecture (AArch64) on Cloud Hypervisor is the GDB supporting. GDB was enabled on the project in release v22.0, but it was only for X86_64. I am setting out to start the journey of adding the support of GDB…

This article introduces the design of virtual GIC (Generic Interrupt Controller) in Cloud Hypervisor. Personally, I think that GIC and Interrupt is the most challenging part of a virtual machine monitor (VMM) software. In Cloud Hypervisor, I believe I have spent half my time in GIC and Interrupt related problems. First Design …

This short article records some tips for debugging Linux kernel in Cloud Hypervisor with gdb. Cloud Hypervisor is an open source virtual machine monitor (VMM) software written in Rust language. It supports x86_64 and aarch64 architectures. For hypervisor, it supports kvm and Hyper-V. For virtualization developers, it would be very…