212 lines
6.3 KiB
Markdown
212 lines
6.3 KiB
Markdown
# 双内核架构与Linux内核交互
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## 需求
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UTSM + Linux 双内核架构，运行 Linux 内核虚拟机，修改 Linux 内核增加双核交互。参考设计: `D:\Code\ZT5`。
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## 架构决策
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- **虚拟化方案**: VMX/EPT 完整虚拟化
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- **分工**: Linux 独占硬件，UTSM 作为监控核（hypervisor 模型）
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- **Linux 版本**: 6.6 LTS
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- **第一阶段范围**: virtio-console + 文件共享
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---
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## UTSM 目录结构
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```
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CODE/UTSM/
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├── arch/x86_64/ # boot.S, idt.c, io.c, serial.c, limine.h
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├── core/ # capability.c, dirty.c, dmp.c, process.c, segment.c, utsm_init.c
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├── crypto/ # kdf.c, stream.c, tweak.c
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├── dkm/ # boot_modules.c, console_early.c, dkm_core.c, kernel_api.c, manifest.c
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├── include/utsm/ # 所有头文件（arena.h, dkm.h, vmm.h, ept.h, hypercall.h, ipc_shm.h 等）
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├── kernel/ # block.c, dsk_loader.c, log.c, main.c, net.c, panic.c
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├── mm/ # arena.c, dma.c
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├── pe/ # pe_loader.c, pe_shim.c, x86emu32.c, pe_service.c
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├── vmm/ # vmx.c, ept.c, vmexit.c, vmm.c, vmexit_asm.S, linux_boot.c,
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│ # linux_loader.c, linux_resume.c, ipc_shm.c, hypercall.c,
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│ # linux_compat.c, virtio_mmio.c, virtio_blk.c, virtio_net.c
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├── MAKEFILE, linker.ld
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```
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---
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## Phase 1.1: VMX 基础设施
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### 核心文件
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| 文件 | 职责 |
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|------|------|
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| `vmm/vmx.c` / `include/utsm/vmx.h` | VMXON/VMXOFF, VMCS 读写, EPT 页表管理 |
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| `vmm/ept.c` / `include/utsm/ept.h` | EPT 4级页表创建/映射/遍历, `ept_gpa_to_hpa()` |
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| `vmm/vmm.c` | VMM 初始化, VMCS 配置(Host/Guest/Controls), 自测程序 |
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| `vmm/vmexit_asm.S` | VM-Exit 汇编入口: 保存/恢复全部 16 个 guest GPR 到 `g_guest_regs` |
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| `vmm/vmexit.c` | VM-Exit 分发: HLT/EPTViolation/异常/CPUID/IO/MSR/VMCALL |
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### 关键 VMCS 字段（vmx.h）
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```c
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// Host State
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VMCS_HOST_CR3, VMCS_HOST_RIP, VMCS_HOST_RSP, VMCS_HOST_GDTR_BASE, VMCS_HOST_TR_SEL
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// Guest State
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VMCS_GUEST_CR0/CR3/CR4, VMCS_GUEST_RIP, VMCS_GUEST_RFLAGS
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VMCS_GUEST_ES/CS/SS/DS/FS/GS/TR/LDTR_SEL
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VMCS_GUEST_GDTR/LDTR_BASE/LIMIT
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VMCS_GUEST_IA32_EFER, VMCS_HOST_IA32_EFER
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// Controls
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VMCS_PIN_CONTROLS, VMCS_CPU_CONTROLS, VMCS_CPU_SECONDARY
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VMCS_ENTRY_CONTROLS, VMCS_EXIT_CONTROLS, VMCS_EPT_POINTER
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```
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### EPT 映射
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```c
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void ept_identity_map(u64 gpa, u64 permissions); // 恒等映射 GPA→HPA
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u64 ept_gpa_to_hpa(u64 gpa); // 4 级 EPT walk（支持 4KB/2MB/1GB 页）
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```
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### 自测流程
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1. `vmm_init()` → VMXON + EPT 初始化
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2. `vmm_self_test()` → 创建测试 guest VMCS, vmlaunch
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3. Guest 执行 HLT → vmexit handler 设置 `g_guest_terminated=1`
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4. 汇编检测终止标志 → 恢复 host 栈返回
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**注意**: VMX 需要 VT-x 硬件支持，QEMU TCG 不支持 VMX。WHPX 在 OVMF 下崩溃。测试需真实硬件。
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---
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## Phase 1.2: Linux Loader
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### 核心文件
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| 文件 | 职责 |
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|------|------|
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| `vmm/linux_loader.c` / `include/utsm/linux_loader.h` | bzImage 解析, boot_params 设置, EPT 映射 |
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| `vmm/linux_boot.c` | Linux guest VMCS 配置 + vmlaunch |
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### GPA 内存布局
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```
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0x00000000-0x003FFFFF 低 RAM (boot_params, GDT 等)
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0x00400000 boot_params GPA
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0x00600000 Guest GDT
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0x01000000 bzImage kernel
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0x03000000 initrd (原 0x04000000, 修复冲突后移至 0x03000000)
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0x04000000-0x04FFFFFF IPC 共享内存 (1MB, e820 reserved)
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0x05000000-0x08FFFFFF Guest RAM (64MB)
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0x0A000000-0x0A0001FF virtio-mmio #0 (blk)
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0x0A000200-0x0A0003FF virtio-mmio #1 (net)
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```
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### Linux Boot Protocol
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```c
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struct setup_header {
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u8 setup_sects, root_flags, syssize[4];
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u16 ram_size, vid_mode, root_dev;
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u8 jump[2], header[4], version[2];
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u32 realmode_swtch, start_sys, kernel_version;
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u8 type_of_loader;
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u8 loadflags; // LOADED_HIGH bit
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u16 initrd_addr_max;
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// ... ext_* fields
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};
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struct boot_params {
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struct screen_info screen_info;
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struct apm_bios_info apm_bios_info;
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u8 pad2[4];
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u64 tboot_addr;
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u8 pad3[24];
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struct e820_entry e820_map[E820_MAX_ENTRIES];
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// ... setup_header at end
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};
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```
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### Linux Boot 流程
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1. 从 Limine boot module 获取 bzImage/initrd
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2. 解析 setup_header, 验证 magic `HdrS`
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3. 设置 boot_params: e820 内存图 + cmdline + initrd 地址/大小
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4. EPT 映射所有 GPA 区域
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5. VMCS 配置 guest 状态 (CR0/3/4, segments, EFER.LME+LMA)
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6. vmlaunch → guest 进入 64 位模式
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---
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## Phase 1.3: IPC 骨架
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### IPC 共享内存（1MB @ GPA 0x04000000）
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```c
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struct utsm_ipc_shm {
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u32 magic; // UTSM_IPC_MAGIC
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u32 version;
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u32 host_to_guest_head, host_to_guest_tail;
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u32 guest_to_host_head, guest_to_host_tail;
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u8 ring_buf[UTSM_IPC_RING_SIZE];
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u8 payload_pool[UTSM_IPC_PAYLOAD_SIZE]; // 1MB, 未用
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};
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```
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### Hypercall ABI（VMCALL）
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Guest 通过 `vmcall(rax=UTSM_HCALL_MAGIC, rdi=op, rsi=arg1, rdx=arg2)` 调用。
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```c
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#define UTSMB_HCALL_PING 0x01
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#define UTSMB_HCALL_HELLO 0x02
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#define UTSMB_HCALL_SHM_INFO 0x03
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#define UTSMB_HCALL_CAP_VALIDATE 0x04
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#define UTSMB_HCALL_UTRW_READ 0x05
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#define UTSMB_HCALL_UTRW_WRITE 0x06
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#define UTSMB_HCALL_DRR_CHECKPOINT 0x07
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#define UTSMB_HCALL_CONSOLE_WRITE 0x08
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#define UTSMB_HCALL_CONSOLE_READ 0x09
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```
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### Linux 侧驱动（utsm_hcall.c）
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- `/dev/utsm` 字符设备
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- ioctl: RECV_MSG / SEND_MSG / SHM_MMAP
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- VMCALL 汇编封装
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### UTSM 启动顺序（kernel/main.c）
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```c
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vmm_init() → vmm_self_test() → ipc_shm_init() → linux_loader_init()
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→ linux_launch() → linux_compat_init() → dsk_load_and_jump()
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```
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---
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## Limine 配置
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`SYSTEM/limine/limine.conf` 中 Linux 模块默认注释（文件不存在时 Limine 启动失败）：
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```
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# /boot/linux-bzImage: cmdline="fuck:config console=ttyS0 nohlt idle=poll"
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# /boot/linux-initrd.img:
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```
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build.sh 成功后自动取消注释。
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---
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## Linux 构建
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`CODE/linux/build.sh` 脚本: 克隆 Linux 6.6 → 安装 UTSM 驱动 → defconfig → bzImage → initramfs → 拷贝产物。
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需 WSL 环境，`KCFLAGS='-std=gnu17'` 修复 gcc 15 C23 兼容性。
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---
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## 构建验证
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- utsm.elf 编译成功（87120 字节），新代码零 warning
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- VMX 自测在 TCG 下优雅降级（打印 "VMX not available"）
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- 真实 VT-x 硬件测试待执行
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