KVM/QEMU Integration

Location: kernel/virtualization/
Type: Kernel Subsystem
Status: ✅ Fully Implemented
Components: KVM Core, QEMU Integration

Overview

FreeWorld OS includes full KVM (Kernel-based Virtual Machine) and QEMU integration, providing hypervisor support for running virtual machines. This system enables hardware-accelerated virtualization with support for multiple VMs, VCPUs, memory virtualization, I/O virtualization, and QEMU device models.

Note: KVM/QEMU integration requires hardware virtualization support (Intel VT-x or AMD-V) and provides near-native performance for virtual machines.

KVM Core

KVM provides the hypervisor interface for creating and managing virtual machines.

Features

  • ✅ KVM device initialization and capability checking
  • ✅ Virtual machine creation and management
  • ✅ Virtual CPU (VCPU) creation and management
  • ✅ Memory virtualization (EPT, shadow paging)
  • ✅ Register access (general, segment, FPU)
  • ✅ VCPU execution (run, pause, resume)
  • ✅ Memory region management
  • ✅ Dirty page tracking
  • ✅ Address translation
  • ✅ Full KVM API support (200+ capabilities)

KVM API Functions

; KVM Initialization
kvm_init() -> status
kvm_check_extension(extension_id) -> capability_value

; Virtual Machine Management
kvm_create_vm(vm_type) -> vm_pointer
kvm_destroy_vm(vm_pointer) -> status

; Virtual CPU Management
kvm_create_vcpu(vm_pointer, cpu_id) -> vcpu_pointer
kvm_destroy_vcpu(vcpu_pointer) -> status
kvm_run_vcpu(vcpu_pointer) -> exit_reason

; Memory Management
kvm_set_user_memory_region(vm_pointer, slot, flags, gpa, size, hva) -> status
kvm_get_vcpu_mmap_size() -> mmap_size

; Register Access
kvm_get_regs(vcpu_pointer, regs_buffer) -> status
kvm_set_regs(vcpu_pointer, regs_buffer) -> status
kvm_get_sregs(vcpu_pointer, sregs_buffer) -> status
kvm_set_sregs(vcpu_pointer, sregs_buffer) -> status
kvm_get_fpu(vcpu_pointer, fpu_buffer) -> status
kvm_set_fpu(vcpu_pointer, fpu_buffer) -> status

; Address Translation
kvm_translate_gva(vcpu_pointer, gva, access_type, translation_buffer) -> status

; Dirty Page Tracking
kvm_get_dirty_log(vm_pointer, slot, dirty_log_buffer) -> status

QEMU Integration

QEMU integration provides device models and machine types for running complete virtual machines.

Features

  • ✅ QEMU VM creation and management
  • ✅ Machine type support (PC, Q35, virt, pseries, s390-ccw-virtio)
  • ✅ Device model support (50+ virtio devices)
  • ✅ CPU model configuration
  • ✅ Memory configuration
  • ✅ VM lifecycle management (start, stop, pause, resume)
  • ✅ VM state management
  • ✅ Migration support (save, load, migrate)

QEMU API Functions

; QEMU Initialization
qemu_init() -> status

; Virtual Machine Management
qemu_create_vm(machine_type, memory_size, vcpu_count) -> qemu_vm_pointer
qemu_destroy_vm(qemu_vm_pointer) -> status

; Device Management
qemu_add_device(qemu_vm_pointer, device_type, device_config) -> device_pointer
qemu_remove_device(qemu_vm_pointer, device_pointer) -> status

; Configuration
qemu_set_machine_type(qemu_vm_pointer, machine_type) -> status
qemu_set_cpu_model(qemu_vm_pointer, cpu_model) -> status
qemu_set_memory(qemu_vm_pointer, memory_size) -> status

; VM Control
qemu_start_vm(qemu_vm_pointer) -> status
qemu_stop_vm(qemu_vm_pointer) -> status
qemu_pause_vm(qemu_vm_pointer) -> status
qemu_resume_vm(qemu_vm_pointer) -> status
qemu_get_vm_state(qemu_vm_pointer, state_buffer) -> status

; Migration
qemu_migrate_vm(qemu_vm_pointer, destination_host) -> status
qemu_save_vm_state(qemu_vm_pointer, file_path) -> status
qemu_load_vm_state(qemu_vm_pointer, file_path) -> status

Supported Device Models

QEMU integration supports 50+ virtio device models:

  • Virtio Network - Virtual network adapter
  • Virtio Block - Virtual disk
  • Virtio SCSI - Virtual SCSI controller
  • Virtio RNG - Random number generator
  • Virtio Balloon - Memory ballooning
  • Virtio 9P - 9P filesystem
  • Virtio GPU - Virtual GPU
  • Virtio Input - Keyboard/mouse
  • Virtio Crypto - Cryptographic operations
  • Virtio VSOCK - Virtual socket
  • Virtio Memory - Memory device
  • Virtio FS - Filesystem sharing
  • Virtio PMEM - Persistent memory
  • Virtio IOMMU - IOMMU device
  • Virtio Sound - Audio device
  • Virtio Video - Video encoder/decoder
  • And 34+ more - Complete virtio device set

Machine Types

  • PC - Standard x86 PC (default)
  • Q35 - Modern x86 PC with PCIe
  • virt - ARM virtual machine
  • pseries - PowerPC pSeries
  • s390-ccw-virtio - IBM Z/s390x

Usage Example

; Initialize KVM and QEMU
call kvm_init
call qemu_init

; Create QEMU VM
mov rdi, MACHINE_TYPE_PC
mov rsi, 0x40000000  ; 1GB memory
mov rdx, 2  ; 2 VCPUs
call qemu_create_vm
mov [qemu_vm], rax

; Add virtio network device
mov rdi, [qemu_vm]
mov rsi, DEVICE_VIRTIO_NET
mov rdx, net_config
call qemu_add_device

; Add virtio block device
mov rdi, [qemu_vm]
mov rsi, DEVICE_VIRTIO_BLK
mov rdx, disk_config
call qemu_add_device

; Start VM
mov rdi, [qemu_vm]
call qemu_start_vm

; VM is now running...

Data Structures

KVM VM Structure (2048 bytes)

  • Magic number and version
  • VM ID and file descriptor
  • VCPU count and memory slot count
  • Status flags
  • Memory regions
  • VCPU pointers

KVM VCPU Structure (4096 bytes)

  • Magic number and version
  • VCPU ID, VM ID, file descriptor
  • CPU ID and status flags
  • Run structure pointer
  • Registers, segment registers, FPU state

QEMU VM Structure (4096 bytes)

  • Magic number and version
  • VM ID and KVM VM pointer
  • Machine type and CPU model
  • Memory size and VCPU count
  • Device count and status flags
  • Migration state
  • Device pointers

KVM Capabilities

FreeWorld OS supports 200+ KVM capabilities including:

  • User memory management
  • IRQ routing and injection
  • MSR filtering
  • Hyper-V enlightenments
  • Nested virtualization
  • Dirty page tracking
  • Memory attributes
  • Guest memory file descriptors
  • VM types
  • And many more

Integration

KVM/QEMU integration integrates with:

  • Memory Management - Uses virtual memory system for guest memory
  • Process Management - VCPUs run as kernel threads
  • Interrupt Handling - Handles VM exits and interrupts
  • Device Drivers - Uses virtio for I/O virtualization
  • System Calls - Provides sys_open, sys_close, sys_ioctl, sys_mmap, sys_munmap

Build System

Virtualization components are built using the Makefile in kernel/virtualization/:

cd kernel/virtualization
make

This produces object files that are linked into the kernel:

  • kvm_core.o - KVM core functionality
  • qemu_integration.o - QEMU integration

Limits and Constraints

  • Maximum VMs: 256
  • Maximum VCPUs per VM: 256
  • Maximum Devices per VM: 64
  • Memory per VM: Limited by host memory
  • Hardware Requirements: Intel VT-x or AMD-V support