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//! Project 3: Hardware Virtualization.
//!
//! In this project, you will implement the hardware-based virtualization and run guest KeOS (gKeOS) on KeV hypervisor.
//! The term "hardware-based virtualization" refers to the process of virtualizing platform hardware to run various
//! operating systems on single hardware with hardware supports. Through this, users can run multiple operating systems on a
//! single hardware platform as if they were running on multiple physical machines with minimal performance degradation.
//!
//! ## Background
//! ### Hardware-based virtualization
//! Hardware-based virtualization refers to the method of providing a virtual computing environment through the use of hardware,
//! typically required for the operations of the virtual machines.
//! This is accomplished using technologies such as Intel-VT or AMD-V, which provide the ability to run codes on another privilege level,
//! enabling full virtualization without the need for OS modification such as binary translation or para-virtualization,
//! with little or minimum performance degradations.
//!
//! Although hardware-based virtualization supports many hardware features,
//! trap-and-emulate is still required as it is difficult to virtualize all instructions through the hardware.
//! Therefore, the hardware assists in virtualization by focusing on frequently occurring or performance-critical instructions.
//! One such example is page table modifications. In the past, shadow page table was used to emulate every memory access permission for
//! each page table entry, but with the hardware-based virtualization, extended page table is used to reduce MMU overhead by
//! allowing the hardware to perform these permission checks on behalf of the software.
//!
//! ## Getting started
//! When you run the following command lines in the project3 directory, keos will panic with "not yet implemented" message.
//! ```/bin/bash
//! $ cargo run --target ../.cargo/x86_64-unknown-keos.json
//! ```
//! ## Outline
//! - [`Extended Page Table`]
//! - [`Memory-mapped I/O`]
//! - [`Lazy paging`]
//!
//! [`Extended Page Table`]: ept
//! [`Memory-mapped I/O`]: mmio
//! [`Lazy paging`]: keos_vm/pager

#![no_std]
#![feature(array_chunks, const_option, new_uninit)]

extern crate alloc;
#[allow(unused_imports)]
#[macro_use]
extern crate keos;

pub mod ept;
pub mod keos_vm;
pub mod mmio;
pub mod simple_ept_vm;

pub mod vmexit {
    #[path = "mmio.rs"]
    pub mod mmio;
}