x86_vlapic

A Rust library for virtualizing x86 Local Advanced Programmable Interrupt Controller (LAPIC) functionality. [Work in Progress].

Overview

This library provides a software implementation of the x86 Local APIC (Advanced Programmable Interrupt Controller) for hypervisor use cases. It virtualizes the LAPIC registers and functionality according to the Intel Software Developer's Manual (SDM) specifications.

⚠️ Important: This is an early-stage library focused solely on timer virtualization. Do not use for full LAPIC emulation yet.

Current Status

• ✅ Timer Virtualization: Fully implemented with support for one-shot, periodic, and TSC-deadline modes
• 🚧 Register Definitions: Complete register layout and bitfield definitions for all LAPIC registers
• 🚧 Interrupt Handling: Framework implemented, core interrupt delivery logic in development
• 🚧 IPI Support: Partial implementation, some functions are placeholders

Architecture

The library is structured into several key modules:

Core Modules

• src/vlapic.rs - Main virtual LAPIC implementation
• src/timer.rs - LAPIC timer virtualization
• src/consts.rs - Constants and register offset definitions
• src/utils.rs - Utility functions

Register Definitions

• src/regs/mod.rs - Main register structure definitions
• src/regs/lvt/ - Local Vector Table register implementations
  • timer.rs - LVT Timer Register
  • lint0.rs - LVT LINT0 Register
  • lint1.rs - LVT LINT1 Register
  • error.rs - LVT Error Register
  • thermal.rs - LVT Thermal Monitor Register
  • perfmon.rs - LVT Performance Counter Register
  • cmci.rs - LVT CMCI Register
• src/regs/timer/ - Timer-related register definitions
  • dcr.rs - Divide Configuration Register
• Other register modules for ICR, ESR, SVR, etc.

Basic Example

use x86_vlapic::EmulatedLocalApic;
use axvisor_api::vmm::{VMId, VCpuId};

// Create a new emulated Local APIC for VM 1, VCPU 0
let vm_id = VMId::from(1 as usize);
let vcpu_id = VCpuId::from(0 as usize);
let apic = EmulatedLocalApic::new(vm_id, vcpu_id);

// Get the shared virtual APIC access page address (static for all instances)
let access_addr = EmulatedLocalApic::virtual_apic_access_addr();
assert!(access_addr.is_aligned(PAGE_SIZE_4K));

// Get the per-VCPU virtual APIC page address
let page_addr = apic.virtual_apic_page_addr();
assert!(page_addr.is_aligned(PAGE_SIZE_4K));

Target Platform

This library is designed for x86_64 architecture and targets x86_64-unknown-none for no-std environments, making it suitable for hypervisor and kernel development.

Related Projects

ArceOS - An experimental modular OS (or Unikernel) AxVisor - Hypervisor implementation

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Note: This is a virtualization library and does not interact with actual hardware LAPIC. It's designed for use in hypervisors and virtual machine monitors.