HyperCalc

An Intel HAXM powered, protected mode, 32 bit, hypervisor addition calculator, written in Rust.

Purpose

None 😏. Mostly just to learn Rust better. Especially looking at the winapi crate.

Requirements

• HAXM for Windows

Notes

Lots of unsafe Rust used. Some things I found interesting related to working with HAXM:

• Real mode is expected to be handled by the user mode component which is usually listed as QEMU. Make sure CR0.PE is set! HAXM does actually allow for real mode if the processor allows/exposes the unrestricted guest VM-execution control.
• It is not required to register a vCPU tunnel to actually run a VM. However if you do you can get extra information such as the VM-exit code.
• Some registers have default values set by HAXM for a newly created vCPU. These include the DR6, and DR7 registers. This happens if after creating a new vCPU you first call HAX_VCPU_GET_REGS.
• The vcpu_state_t is essentially just a limited version of a VMCS.
• Remember that VMCS fields may not be sized accurately to what they reflect in an actual OS. I'm looking at you segment descriptors limits!🧐
• The Descriptor Cache (https://wiki.osdev.org/Descriptor_Cache)

Useful resources:

• HAXM Device API
• Semi-Working Example