[WIP] Migrate x86_64-qemu-virt platform to kbootloader

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

Original prompt

Background

The aarch64-qemu-virt platform has been migrated to use the unified kbootloader crate for boot entry. x86_64-qemu-virt is still using platform-private boot.rs/multiboot.S and manual entry functions; the goal is to migrate this platform to the new system, with all entry code unified in kbootloader.

Tasks for this PR (x86_64-qemu-virt only)

1. Implement x86_64 arch support in kbootloader:
   • Add arch/x86_64/entry.rs: provides __primary_switched(magic, mbi) and __secondary_switched(magic); validates the Multiboot magic, gets current cpu_id using raw_cpuid, calls INIT_PERCPU, INIT_TRAP, then call_kernel_entry.
   • Add arch/x86_64/boot.rs: includes unified multiboot.S as global_asm!; symbols/param config through kbuild_config.
   • Move/merge multiboot.S (and differentiate cbit_mask, entry names etc through kconfig).
   • Cargo.toml: Add [target.'cfg(target_arch = "x86_64")'.dependencies] raw_cpuid = "11"
   • Update arch/mod.rs to include/use x86_64.
2. Clean up x86_64-qemu-virt platform:
   • Remove boot.rs, all platform-specific global_asm for boot.
   • Remove all platform-level entryers (rust_entry, rust_entry_secondary, current_cpu_id, multiboot magic check etc) from lib.rs/init.rs.
   • Use extern crate kbootloader;, not mod boot; in lib.rs.
   • Remove call to kcpu::boot::init_trap() from early_init/init.rs; boot init now handled via distributed_slice.
   • Keep SMP/secondary startup (mp.rs, ap_start.S) unchanged; ap_entry32 global symbol is provided by kbootloader multiboot.S.
3. Ensure platform builds and doc all config/entry changes (README/notes as needed).

Design/compatibility notes

• All changes apply ONLY to x86_64-qemu-virt in this PR (multi-PR plan, one per platform).
• Use only parameterized multiboot.S in kbootloader, no platform subdir .S. Use kconfig for CBIT_MASK, PHYS_VIRT_OFFSET, BOOT_STACK_SIZE etc.
• INIT_PERCPU and INIT_TRAP must be registered (by kcpu crate, to ensure migration safety for other platforms).

Next PRs

• Subsequent PRs will migrate x86-csv and aarch64-crosvm-virt using the same procedure, and expand/merge boot hooks as needed for those platforms.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: j 从kbootloader设计来看 我希望他尽可能少依赖外部库 不过没有办法的花，用 target dependency 引入也行 k： 这个校验逻辑是保留在 kbootloader 中 l) 统一 multiboot.S 的方案 可以用一份 只要你确认功能不会互相影响 m： INIT_PERCPU 的签名应该是 fn(usize) n) 我们可以在 kbootloader 中提供一个可选的 PLATFORM_PRE_MMU 回调 让platform决定是否有额外操作 去决定是否实现 o) 可以用 boot_device_mm[(start, end), (start ,end)] 和 BOOT_NORMAL_MM((start, end), (start ,end)) 配置 然后动态计算映射页表 p 可以

Assistant:

好的，所有技术细节已经确认清楚。让我整理一下完整的实现方案，然后开始创建 PR。

最终实现方案总结

1. kbootloader 新增 x86_64 架构支持

• 新增 src/arch/x86_64/ 模块：包含 mod.rs、entry.rs、multiboot.S
• 统一 multiboot.S：合并两个平台的汇编，使用 {cbit_mask} 参数（非 SEV 时为 0），保留 _start32 + _start（64-bit 跳板）兼容两种入口
• __primary_switched：校验 multiboot magic → call_init_percpu!(cpu_id) → call_init_trap!() → call_kernel_entry!(PRIMARY_KERNEL_ENTRY, cpu_id, mbi)
• __secondary_switched：call_init_percpu!(cpu_id) → call_init_trap!() → call_kernel_entry!(SECOND_KERNEL_ENTRY, cpu_id)
• current_cpu_id()：通过 target dependency 引入 raw_cpuid

2. 新增 distributed_slice

• INIT_PERCPU: [fn(usize)] — 签名 fn(cpu_id: usize)
• 新增 call_init_percpu! 宏
• 调用顺序：init_percpu → init_trap → kernel_entry

3. aarch64 新增 PLATFORM_PRE_MMU 回调

• PLATFORM_PRE_MMU: [fn()] — 可选，platform 决定是否注册
• 在 create_boot_page_tables() 之前调用
• crosvm 注册此回调实现 kvm_guard_granule_init + do_xmap_granules

4. aarch64 页表映射可配置化

• 通过 kbuild_config 新增 BOOT_DEVICE_MM 和 BOOT_NORMAL_MM 配置
• create_boot_page_tables() 根据配置动态创建映射

5. 三个平台迁移

• x86_64-qemu-virt：删除 boot.rs，lib.rs 中 extern crate kbootloader，init.rs 移除 init_trap 调用
• x86-csv：同上，额外处理 cbit_mask
• aarch64-crosvm-virt：删除 boot.rs，统一使用 kbootloader 的 _start（带 MZ header，注释说明 crosvm 待测试），init.rs 移除 init_trap，power.rs 引用改为 kbootloader::arch::_start_secondary

让我现在创建 PR。

Assistant: I've submitted the pull request to the coding agent. It will create a PR on the dyn_bootloader branch of guoweikang/x-kernel that migrates all three remaining platforms (x86_64-qemu-virt, x86-csv, aarch64-crosvm-virt) to use the unified kbootloader crate.

Here's a summary of the migration plan the agent will implement:

kbootloader Enhancements

1. INIT_PERCPU distributed_slice — fn(usize) for x86_64's percpu init before init_trap
2. PLATFORM_PRE_MMU distributed_slice — fn() for crosvm's KVM guard granule ops before MMU enable
3. Configurable aarch64 boot page tables via BOOT_DEVICE_MM / BOOT_NORMAL_MM kconfig arrays
4. x86_64 arch support — unified multiboot.S (with cbit_mask param), Rust entry points, multiboot magic validation
5. INIT_PERCPU calls added to existing aarch64 entr...

This pull request was created from Copilot chat.

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