Building a Hypervisor in Rust

From First Principles to a Full Virtualization Platform

Introduction: The Virtual Machine

1. Why Rust?
2. What This Book Covers
3. How to Use This Book
4. What This Book Is Not

Chapter 1: Project Foundation — Bare-Metal Rust on x86_64

1. Setting Up the Cross-Compilation Toolchain
2. Memory Allocator for no_std
3. The Linker Script
4. The Bootloader Handoff — Multiboot2 Entry
5. Entering Long Mode from Real Mode
6. The Core Kernel Entry Point
7. Memory Layout and Early Allocator
8. Early Console — Serial Port Output

Chapter 2: Understanding x86_64 Virtualization Hardware

1. The Root/Non-Root Execution Mode Model
2. CPUID Detection and Feature Enumeration
3. Intel VT-x Architecture — VMXON, VMCS, and VM Entry/Exit
4. AMD-V Architecture — SVM and the VMCB
5. The Virtualization Instruction Set
6. Hypervisor Initialization

Chapter 3: Guest Memory Management — Extended Page Tables

1. The Two-Level Translation Problem
2. EPT Page Table Structure
3. AMD NPT — The Parallel Path
4. Building Guest RAM Mappings

Chapter 4: VMCS Configuration and Guest CPU State

1. VMCS Layout and Field Encoding
2. Guest-State Area Configuration
3. Host-State Area Configuration
4. VMCS Validation and Error Codes

Chapter 5: Virtual CPU Lifecycle — Launch, Resume, and Exits

1. The vCPU Data Structure
2. VMLAUNCH vs VMRESUME — The First Entry Problem
3. VM Entry Failures and Recovery

Chapter 6: Interrupts, Exceptions, and the APIC

1. The x86 Interrupt Model Recap
2. Virtualizing the IDT — Exception Bitmap Control
3. Local APIC Virtualization
4. I/O APIC and Interrupt Routing
5. Event Injection — Delivering Interrupts to Guests

Chapter 7: I/O Virtualization — MMIO, PIO, and PCI Passthrough

1. Memory-Mapped I/O via EPT Intercepts
2. Port I/O Interception — IN/OUT Instructions
3. PCI Configuration Space Access
4. MSI and MSI-X Virtualization
5. Device Passthrough Fundamentals

Chapter 8: Virtual Devices — Serial, RTC, and PIT Emulation

1. The VirtIO Framework — Paravirtualized Device Standard
2. Serial Port Emulation (COM1)
3. RTC and PIT Emulation
4. HPET — High Precision Event Timer
5. ACPI Tables Construction

Chapter 9: Storage and Block Device Virtualization

1. VirtIO Block Device Specification
2. Building the VirtIO Block Backend
3. VirtIO Console — Character Device Virtualization
4. Raw Disk Access and Backing Store Management

Chapter 10: Networking Virtualization

1. VirtIO Net Device Specification
2. Building the VirtIO Net Backend
3. TAP Device Integration on Linux
4. MAC Address and VLAN Handling
5. Network Performance Considerations

Chapter 11: Guest Boot — BIOS/UEFI Firmware Loading

1. BIOS vs UEFI Boot Paths
2. Loading SeaBIOS — The Simple Path
3. Loading OVMF — UEFI Firmware
4. Guest Kernel Direct Boot (no firmware)
5. Debugging the First Guest Boot

Chapter 12: Multi-vCPU Systems and Scheduling

1. vCPU Pinning and Host Thread Mapping
2. Inter-Processor Interrupts (IPIs)
3. vCPU Scheduling Strategies
4. SMP Boot Sequence — Waking APs
5. Cross-vCPU State and Communication

Chapter 13: Performance, Debugging, and Security

1. Profiling VM Exit Overhead
2. TSC Scaling and Clock Virtualization
3. GDB Stub and Hypervisor Debugging
4. Security Hardening — Isolation and Sandboxing
5. Error Handling and Recovery Patterns
6. Benchmarking Methodology
7. Troubleshooting Common Failures
8. Cross-Platform Considerations
9. Production Deployment Checklist

Conclusion: What We Built and Where to Go Next

References