feat: UEFI MVP

Co-authored-by: Martin Kröning <martin.kroening@eonerc.rwth-aachen.de>
Signed-off-by: Martin Kröning <martin.kroening@eonerc.rwth-aachen.de>

Cargo.toml

@@ -40,7 +40,6 @@ spinning_top = "0.3"
 [target.'cfg(target_os = "uefi")'.dependencies]
 uefi = { version = "0.27", features = ["alloc"] }
 uefi-services = { version = "0.24", default-features = false, features = ["panic_handler", "qemu"] }
-qemu-exit = "3"
 
 [target.'cfg(target_arch = "riscv64")'.dependencies]
 fdt = "0.1"

README.md

@@ -6,6 +6,20 @@ This project is a bootloader to run the [Hermit kernel](https://github.com/hermi
 
 * [`rustup`](https://www.rust-lang.org/tools/install)
 
+### UEFI Boot in x86-64 QEMU
+
+As QEMU does not include a UEFI implementation, we have to get the Open Virtual Machine Firmware (OVMF) UEFI implementation separately.
+On Linux, you can usually install it with your package manager.
+Alternatively, you can run this command to get `OVMF_CODE.fd` and `OVMF_VARS.fd` from the Debian package on any system:
+
+```bash
+wget -O - http://security.debian.org/debian-security/pool/updates/main/e/edk2/ovmf_2022.11-6+deb12u1_all.deb \
+    | tar xvf - -O data.tar.xz \
+    | tar xvf - --strip-components=4 ./usr/share/OVMF/OVMF_CODE_4M.fd ./usr/share/OVMF/OVMF_VARS_4M.fd \
+    && mv OVMF_CODE_4M.fd OVMF_CODE.fd \
+    && mv OVMF_VARS_4M.fd OVMF_VARS.fd
+```
+
 ## Building
 
 ```bash
@@ -34,6 +48,34 @@ qemu-system-x86_64 \
     -initrd <APP>
 ```
 
+#### UEFI Boot
+
+For booting from UEFI, we have to set up an EFI system partition (ESP).
+OVMF will automatically load and execute the loader if placed at `\efi\boot\bootx64.efi` in the ESP.
+The Hermit application has to be next to the loader with the filename `hermit-app`.
+You can set the ESP up with the following commands:
+
+```bash
+$ mkdir -p esp/efi/boot
+$ cp <LOADER> esp/efi/boot/bootx64.efi
+$ cp <APP> esp/efi/boot/hermit-app
+```
+
+Then, you can boot Hermit like this:
+
+```bash
+qemu-system-x86_64 \
+    -enable-kvm \
+    -cpu host \
+    -smp 1 \
+    -m 512M \
+    -device isa-debug-exit,iobase=0xf4,iosize=0x04 \
+    -display none -serial stdio \
+    -drive if=pflash,format=raw,readonly=on,file=OVMF_CODE.fd \
+    -drive if=pflash,format=raw,readonly=on,file=OVMF_VARS.fd \
+    -drive format=raw,file=fat:rw:esp
+```
+
 #### No KVM
 
 If you want to emulate x86-64 instead of using KVM, omit `-enable-kvm` and set the CPU explicitly to a model of your choice, for example `-cpu Skylake-Client`.

src/arch/x86_64/mod.rs

@@ -18,8 +18,7 @@ pub use console::Console;
 
 #[cfg(target_os = "none")]
 const KERNEL_STACK_SIZE: u64 = 32_768;
-#[cfg(target_os = "none")]
-const SERIAL_IO_PORT: u16 = 0x3F8;
+pub const SERIAL_IO_PORT: u16 = 0x3F8;
 
 #[cfg(target_os = "none")]
 unsafe fn map_memory(address: usize, memory_size: usize) -> usize {
@@ -45,8 +44,7 @@ pub unsafe fn get_memory(memory_size: u64) -> u64 {
 	unsafe { map_memory(address, memory_size as usize) as u64 }
 }
 
-#[cfg(target_os = "none")]
-unsafe fn enter_kernel(
+pub unsafe fn enter_kernel(
 	stack: *mut u8,
 	entry: *const (),
 	raw_boot_info: &'static hermit_entry::boot_info::RawBootInfo,

src/os/uefi/fdt.rs

@@ -0,0 +1,36 @@
+use alloc::format;
+use alloc::vec::Vec;
+
+use vm_fdt::{FdtWriter, FdtWriterNode, FdtWriterResult};
+
+pub struct Fdt {
+	writer: FdtWriter,
+	root_node: FdtWriterNode,
+}
+
+impl Fdt {
+	pub fn new() -> FdtWriterResult<Self> {
+		let mut writer = FdtWriter::new()?;
+
+		let root_node = writer.begin_node("")?;
+		writer.property_string("compatible", "hermit,uefi")?;
+		writer.property_u32("#address-cells", 0x2)?;
+		writer.property_u32("#size-cells", 0x2)?;
+
+		Ok(Self { writer, root_node })
+	}
+
+	pub fn finish(mut self) -> FdtWriterResult<Vec<u8>> {
+		self.writer.end_node(self.root_node)?;
+
+		self.writer.finish()
+	}
+
+	pub fn rsdp(mut self, rsdp: u64) -> FdtWriterResult<Self> {
+		let rsdp_node = self.writer.begin_node(&format!("hermit,rsdp@{rsdp:x}"))?;
+		self.writer.property_array_u64("reg", &[rsdp, 1])?;
+		self.writer.end_node(rsdp_node)?;
+
+		Ok(self)
+	}
+}

src/os/uefi/mod.rs

@@ -1,29 +1,63 @@
 mod console;
+mod fdt;
 
-use alloc::string::String;
 use alloc::vec::Vec;
+use core::ffi::c_void;
+use core::mem::MaybeUninit;
+use core::ops::Range;
+use core::{fmt, slice};
 
+use align_address::Align;
+use hermit_entry::boot_info::{
+	BootInfo, DeviceTreeAddress, HardwareInfo, PlatformInfo, SerialPortBase,
+};
+use hermit_entry::elf::{KernelObject, LoadedKernel};
 use log::info;
-use qemu_exit::QEMUExit;
+use sptr::Strict;
 use uefi::fs::{FileSystem, Path};
 use uefi::prelude::*;
+use uefi::table::boot::{
+	AllocateType, BootServices, MemoryDescriptor, MemoryMap, MemoryType, PAGE_SIZE,
+};
+use uefi::table::cfg;
 
 pub use self::console::CONSOLE;
+use self::fdt::Fdt;
+use crate::{arch, BootInfoExt};
 
 // Entry Point of the Uefi Loader
 #[entry]
 fn loader_main(_handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
 	uefi_services::init(&mut system_table).unwrap();
 	crate::log::init();
+	let bs = system_table.boot_services();
 
-	let app = read_app(system_table.boot_services());
+	let kernel_image = read_app(bs);
+	let kernel = KernelObject::parse(&kernel_image).unwrap();
 
-	let string = String::from_utf8(app).unwrap();
-	println!("{string}");
+	let kernel_memory = bs.alloc_page_slice(kernel.mem_size()).unwrap();
+	let kernel_memory = &mut kernel_memory[..kernel.mem_size()];
 
-	let custom_exit_success = 3;
-	let qemu_exit_handle = qemu_exit::X86::new(0xf4, custom_exit_success);
-	qemu_exit_handle.exit_success()
+	let kernel_info = kernel.load_kernel(kernel_memory, kernel_memory.as_ptr() as u64);
+
+	let rsdp = system_table.rsdp();
+
+	drop(kernel_image);
+
+	let fdt = Fdt::new()
+		.unwrap()
+		.rsdp(u64::try_from(rsdp.expose_addr()).unwrap())
+		.unwrap()
+		.finish()
+		.unwrap();
+
+	let (_runtime_system_table, mut memory_map) =
+		system_table.exit_boot_services(MemoryType::LOADER_DATA);
+
+	let desc = largest_free_memory_region(&mut memory_map);
+	let phys_addr_range = desc.phys_start..desc.phys_start + (desc.page_count * PAGE_SIZE as u64);
+
+	unsafe { boot_kernel(kernel_info, fdt, phys_addr_range) }
 }
 
 fn read_app(bt: &BootServices) -> Vec<u8> {
@@ -42,3 +76,124 @@ fn read_app(bt: &BootServices) -> Vec<u8> {
 
 	data
 }
+
+pub unsafe fn boot_kernel(
+	kernel_info: LoadedKernel,
+	fdt: Vec<u8>,
+	phys_addr_range: Range<u64>,
+) -> ! {
+	let LoadedKernel {
+		load_info,
+		entry_point,
+	} = kernel_info;
+
+	let device_tree = DeviceTreeAddress::new(u64::try_from(fdt.leak().as_ptr().addr()).unwrap());
+
+	let boot_info = BootInfo {
+		hardware_info: HardwareInfo {
+			phys_addr_range,
+			serial_port_base: SerialPortBase::new(arch::SERIAL_IO_PORT),
+			device_tree,
+		},
+		load_info,
+		platform_info: PlatformInfo::Fdt,
+	};
+
+	let stack = usize::try_from(boot_info.load_info.kernel_image_addr_range.end)
+		.unwrap()
+		.align_down(PAGE_SIZE);
+	let entry = sptr::from_exposed_addr(entry_point.try_into().unwrap());
+	let stack = sptr::from_exposed_addr_mut(stack);
+	let raw_boot_info = boot_info.write();
+
+	unsafe { arch::enter_kernel(stack, entry, raw_boot_info) }
+}
+
+trait BootServicesExt {
+	fn alloc_page_slice(&self, size: usize) -> uefi::Result<&'static mut [MaybeUninit<u8>]>;
+}
+
+impl BootServicesExt for BootServices {
+	fn alloc_page_slice(&self, size: usize) -> uefi::Result<&'static mut [MaybeUninit<u8>]> {
+		let size = size.align_up(PAGE_SIZE);
+		let phys_addr = self.allocate_pages(
+			AllocateType::AnyPages,
+			MemoryType::LOADER_DATA,
+			size / PAGE_SIZE,
+		)?;
+		let ptr = sptr::from_exposed_addr_mut(usize::try_from(phys_addr).unwrap());
+		Ok(unsafe { slice::from_raw_parts_mut(ptr, size) })
+	}
+}
+
+trait SystemTableBootExt {
+	/// Returns the RSDP.
+	///
+	/// This must be called before exiting boot services.
+	/// See [5.2.5.2. Finding the RSDP on UEFI Enabled Systems — ACPI Specification 6.5 documentation](https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#finding-the-rsdp-on-uefi-enabled-systems) for details.
+	fn rsdp(&self) -> *const c_void;
+}
+
+impl SystemTableBootExt for SystemTable<Boot> {
+	fn rsdp(&self) -> *const c_void {
+		let config_table = self.config_table();
+		let (rsdp, version) = if let Some(entry) = config_table
+			.iter()
+			.find(|entry| entry.guid == cfg::ACPI2_GUID)
+		{
+			(entry.address, 2)
+		} else {
+			let entry = config_table
+				.iter()
+				.find(|entry| entry.guid == cfg::ACPI_GUID)
+				.unwrap();
+			(entry.address, 1)
+		};
+		info!("Found ACPI {version} RSDP at {rsdp:p}");
+		rsdp
+	}
+}
+
+fn largest_free_memory_region<'a>(memory_map: &'a mut MemoryMap<'a>) -> &'a MemoryDescriptor {
+	memory_map.sort();
+
+	let max_desc = memory_map
+		.entries()
+		.filter(|desc| desc.ty == MemoryType::CONVENTIONAL)
+		.max_by_key(|desc| desc.page_count)
+		.unwrap();
+
+	info!("Memory map:");
+	for desc in memory_map.entries() {
+		if desc == max_desc {
+			info!("largest free memory region:");
+		}
+		info!("{}", desc.display());
+	}
+
+	max_desc
+}
+
+trait MemoryDescriptorExt {
+	fn display(&self) -> MemoryDescriptorDisplay<'_>;
+}
+
+impl MemoryDescriptorExt for MemoryDescriptor {
+	fn display(&self) -> MemoryDescriptorDisplay<'_> {
+		MemoryDescriptorDisplay { inner: self }
+	}
+}
+
+struct MemoryDescriptorDisplay<'a> {
+	inner: &'a MemoryDescriptor,
+}
+
+impl<'a> fmt::Display for MemoryDescriptorDisplay<'a> {
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+		write!(
+			f,
+			"start: {:#12x}, pages: {:#8x}, type: {:?}",
+			self.inner.phys_start, self.inner.page_count, self.inner.ty
+		)
+	}
+}

xtask/src/ci/qemu.rs

@@ -49,7 +49,10 @@ impl Qemu {
 
 			sh.create_dir("target/esp/efi/boot")?;
 			sh.copy_file(self.build.dist_object(), "target/esp/efi/boot/bootx64.efi")?;
-			sh.write_file("target/esp/efi/boot/hermit-app", "Hello, UEFI!\n")?;
+			sh.copy_file(
+				self.build.ci_image(&self.image),
+				"target/esp/efi/boot/hermit-app",
+			)?;
 		}
 
 		let target = self.build.target();
@@ -202,13 +205,10 @@ impl Qemu {
 	}
 
 	fn memory(&self) -> usize {
-		let mut memory = 32usize;
-		if self.image == "hello_c" {
-			memory = memory.max(64);
-		}
+		let mut memory = 64usize;
 		match self.build.target() {
 			Target::X86_64Uefi => {
-				memory = memory.max(64);
+				memory = memory.max(512);
 			}
 			Target::Aarch64 => {
 				memory = memory.max(256);