feat(acpi): add RSDP discovery from BIOS memory regions. (#2124)

* acpi: add RSDP discovery from BIOS memory regions.

impl ACPI RSDP discovery for legacy BIOS platforms by scanning the standard locations defined by the ACPI specification.

The impl follow the linux kernel drivers/acpi/acpica/tbxfroot.c

checking:

- EBDA region
- BIOS reserved memory range 0xE0000-0xFFFFF

Signed-off-by: DonjuanPlatinum <donplat@barrensea.org>

* 1. change RSDP scan before mm_init into early_init to follow the linux
   impl.
2. when len < 36 || len > available_len, rsdp_valid return false

* fmt

* change the scan window into min(1KiB, 0xA0000 - ebda_phys)

Signed-off-by: Donjuanplatinum <donplat@barrensea.org>

* fix EarlyRemapPage.

Signed-off-by: Donjuanplatinum <donplat@barrensea.org>

* Update acpi and aml dependencies

Updated acpi and aml dependencies to a new commit hash.

* fix(acpi): add legacy BIOS RSDP fallback

Signed-off-by: longjin <longjin@dragonos.org>

* fix(acpi): bound early RSDP mappings

Signed-off-by: longjin <longjin@dragonos.org>

---------

Signed-off-by: DonjuanPlatinum <donplat@barrensea.org>
Signed-off-by: Donjuanplatinum <donplat@barrensea.org>
Signed-off-by: longjin <longjin@dragonos.org>
Co-authored-by: longjin <longjin@dragonos.org>

Author: donjuanplatinum

kernel/Cargo.lock

@@ -36,8 +36,8 @@ fifo_demo = []
 
 # 运行时依赖项
 [dependencies]
-acpi = { git = "https://git.mirrors.dragonos.org.cn/DragonOS-Community/acpi-rs.git", rev = "282df2af7b" }
-aml = { git = "https://git.mirrors.dragonos.org.cn/DragonOS-Community/acpi-rs.git", rev = "282df2af7b" }
+acpi = { git = "https://git.mirrors.dragonos.org.cn/DragonOS-Community/acpi-rs.git", rev = "1bbdc9767ac72725fa7bdbc53260b5b6baa2bce1" }
+aml = { git = "https://git.mirrors.dragonos.org.cn/DragonOS-Community/acpi-rs.git", rev = "1bbdc9767ac72725fa7bdbc53260b5b6baa2bce1" }
 asm_macros = { path = "crates/asm_macros" }
 atomic_enum = "=0.2.0"
 bit_field = "=0.10"

kernel/Cargo.toml

@@ -27,6 +27,7 @@ use super::{
 mod boot;
 mod multiboot2;
 mod pvh;
+mod rsdp;
 
 mod boot_params;
 

kernel/src/arch/x86_64/init/mod.rs

@@ -22,12 +22,23 @@ use crate::{
     mm::{memblock::mem_block_manager, PhysAddr},
 };
 
+use super::rsdp::{cache_bios_rsdp_result, cached_bios_rsdp};
+
 pub(super) const MULTIBOOT2_ENTRY_MAGIC: u32 = multiboot2::MAGIC;
 static MB2_INFO: Lazy<BootInformation> = Lazy::new();
 const MB2_RAW_INFO_MAX_SIZE: usize = 4096;
 
 static mut MB2_RAW_INFO: [u8; MB2_RAW_INFO_MAX_SIZE] = [0u8; MB2_RAW_INFO_MAX_SIZE];
 
+fn has_efi_context(boot_info: &BootInformation) -> bool {
+    boot_info.efi_sdt32_tag().is_some()
+        || boot_info.efi_sdt64_tag().is_some()
+        || boot_info.efi_memory_map_tag().is_some()
+        || boot_info.efi_bs_not_exited_tag().is_some()
+        || boot_info.efi_ih32_tag().is_some()
+        || boot_info.efi_ih64_tag().is_some()
+}
+
 fn mb2_rsdp_v1_tag_to_rsdp_struct(tag: &RsdpV1Tag) -> Rsdp {
     Rsdp {
         signature: tag.signature,
@@ -70,17 +81,23 @@ impl BootCallbacks for Mb2Callback {
     }
 
     fn init_acpi_args(&self) -> Result<BootloaderAcpiArg, SystemError> {
-        if let Some(v1_tag) = MB2_INFO.get().rsdp_v1_tag() {
-            Ok(BootloaderAcpiArg::Rsdt(mb2_rsdp_v1_tag_to_rsdp_struct(
-                v1_tag,
-            )))
-        } else if let Some(v2_tag) = MB2_INFO.get().rsdp_v2_tag() {
-            Ok(BootloaderAcpiArg::Xsdt(mb2_rsdp_v2_tag_to_rsdp_struct(
+        let boot_info = MB2_INFO.get();
+        if let Some(v2_tag) = boot_info.rsdp_v2_tag() {
+            return Ok(BootloaderAcpiArg::Xsdt(mb2_rsdp_v2_tag_to_rsdp_struct(
                 v2_tag,
-            )))
-        } else {
-            Ok(BootloaderAcpiArg::NotProvided)
+            )));
+        }
+        if let Some(v1_tag) = boot_info.rsdp_v1_tag() {
+            return Ok(BootloaderAcpiArg::Rsdt(mb2_rsdp_v1_tag_to_rsdp_struct(
+                v1_tag,
+            )));
+        }
+        if let Some(paddr) = cached_bios_rsdp()? {
+            log::info!("multiboot2: found RSDP at {:#x}", paddr.data());
+            return Ok(BootloaderAcpiArg::Rsdp(paddr));
         }
+
+        Ok(BootloaderAcpiArg::NotProvided)
     }
 
     fn init_kernel_cmdline(&self) -> Result<(), SystemError> {
@@ -209,6 +226,16 @@ impl BootCallbacks for Mb2Callback {
         // setup kernel load base
         self.setup_kernel_load_base();
 
+        // Legacy BIOS fallback is valid only when no ACPI tag and no EFI
+        // context were supplied. UEFI systems must use their configuration
+        // table and must not probe the fixed Legacy BIOS regions.
+        if mb2_info.rsdp_v2_tag().is_none()
+            && mb2_info.rsdp_v1_tag().is_none()
+            && !has_efi_context(mb2_info)
+        {
+            cache_bios_rsdp_result();
+        }
+
         Ok(())
     }
 

kernel/src/arch/x86_64/init/multiboot2.rs

@@ -21,6 +21,8 @@ use crate::{
 
 mod param;
 
+use super::rsdp::{cache_bios_rsdp_result, cached_bios_rsdp};
+
 static START_INFO: Lazy<HvmStartInfo> = Lazy::new();
 
 struct PvhBootCallback;
@@ -31,12 +33,29 @@ impl BootCallbacks for PvhBootCallback {
     }
 
     fn init_acpi_args(&self) -> Result<BootloaderAcpiArg, SystemError> {
-        let rsdp_paddr = PhysAddr::new(START_INFO.get().rsdp_paddr as usize);
+        let si = START_INFO.get();
+        log::info!(
+            "pvh: HvmStartInfo: magic={:#010x} version={} flags={:#x} nr_modules={} rsdp_paddr={:#x} memmap_paddr={:#x} memmap_entries={}",
+            si.magic, si.version, si.flags, si.nr_modules,
+            si.rsdp_paddr, si.memmap_paddr, si.memmap_entries
+        );
+
+        let rsdp_paddr = PhysAddr::new(si.rsdp_paddr as usize);
+
+        // if RSDP has been provided
         if rsdp_paddr.data() != 0 {
-            Ok(BootloaderAcpiArg::Rsdp(rsdp_paddr))
-        } else {
-            Ok(BootloaderAcpiArg::NotProvided)
+            return Ok(BootloaderAcpiArg::Rsdp(rsdp_paddr));
         }
+
+        // The bootloader did not provide an RSDP. Consume the shared x86
+        // early-discovery result without touching EarlyIoRemap after mm_init.
+        if let Some(paddr) = cached_bios_rsdp()? {
+            log::info!("pvh: found RSDP at {:#x}", paddr.data());
+            return Ok(BootloaderAcpiArg::Rsdp(paddr));
+        }
+
+        log::warn!("pvh: RSDP not found");
+        Ok(BootloaderAcpiArg::NotProvided)
     }
 
     fn init_kernel_cmdline(&self) -> Result<(), SystemError> {
@@ -86,7 +105,7 @@ impl BootCallbacks for PvhBootCallback {
 
                 total_mem_size += size;
                 match typ {
-                    param::E820Type::Ram => {
+                    E820Type::Ram => {
                         usable_mem_size += size;
                         mem_block_manager()
                             .add_block(start, size)
@@ -121,6 +140,16 @@ impl BootCallbacks for PvhBootCallback {
             total_mem_size,
             usable_mem_size
         );
+
+        // Discover the RSDP here, in the early boot stage: the bootstrap page
+        // table is still active and mm_init has not run yet, so EarlyIoRemap may
+        // be used safely (this mirrors Linux, which scans the RSDP in setup_arch
+        // via early_memremap). If the bootloader already provided rsdp_paddr we
+        // skip the scan. The result is cached for init_acpi_args.
+        if start_info.rsdp_paddr == 0 {
+            cache_bios_rsdp_result();
+        }
+
         Ok(())
     }
 

kernel/src/arch/x86_64/init/pvh/mod.rs

@@ -160,7 +160,7 @@ pub struct HvmMemmapTableEntry {
 }
 
 /// The E820 types known to the kernel.
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 #[repr(u32)]
 pub enum E820Type {
     Ram = 1,