ostd/arch/x86/kernel/acpi/
mod.rs

1// SPDX-License-Identifier: MPL-2.0
2
3// Set this module's log prefix for `ostd::log`.
4macro_rules! __log_prefix {
5    () => {
6        "acpi: "
7    };
8}
9
10pub(in crate::arch) mod dmar;
11pub(in crate::arch) mod remapping;
12
13use core::{num::NonZeroU8, ptr::NonNull};
14
15use acpi::{
16    AcpiHandler, AcpiTables,
17    address::AddressSpace,
18    fadt::{Fadt, IaPcBootArchFlags},
19    mcfg::Mcfg,
20    rsdp::Rsdp,
21};
22use spin::Once;
23
24use crate::{
25    boot::{self, BootloaderAcpiArg},
26    info,
27    mm::paddr_to_vaddr,
28    warn,
29};
30
31#[derive(Clone, Debug)]
32pub(crate) struct AcpiMemoryHandler {}
33
34impl AcpiHandler for AcpiMemoryHandler {
35    unsafe fn map_physical_region<T>(
36        &self,
37        physical_address: usize,
38        size: usize,
39    ) -> acpi::PhysicalMapping<Self, T> {
40        let virtual_address = NonNull::new(paddr_to_vaddr(physical_address) as *mut T).unwrap();
41
42        // SAFETY: The caller should guarantee that `physical_address..physical_address + size` is
43        // part of the ACPI table. Then the memory region is mapped to `virtual_address` and is
44        // valid for read and immutable dereferencing.
45        // FIXME: The caller guarantee only holds if we trust the hardware to provide a valid ACPI
46        // table. Otherwise, if the table is corrupted, it may reference arbitrary memory regions.
47        unsafe {
48            acpi::PhysicalMapping::new(physical_address, virtual_address, size, size, self.clone())
49        }
50    }
51
52    fn unmap_physical_region<T>(_region: &acpi::PhysicalMapping<Self, T>) {}
53}
54
55struct SyncAcpiTables(Option<AcpiTables<AcpiMemoryHandler>>);
56
57// SAFETY: This relies on the current implementation of `AcpiTables`,
58// which provides thread-safe access to read-only ACPI table data,
59// so `Sync` is sound for the wrapper.
60// FIXME: It depends on implementation details of `AcpiTables`, which should be avoided.
61unsafe impl Sync for SyncAcpiTables {}
62
63static ACPI_TABLES: Once<SyncAcpiTables> = Once::new();
64
65pub(crate) fn get_acpi_tables() -> Option<&'static AcpiTables<AcpiMemoryHandler>> {
66    let acpi_tables = ACPI_TABLES.call_once(|| {
67        let acpi_tables = match boot::EARLY_INFO.get().unwrap().acpi_arg {
68            BootloaderAcpiArg::Rsdp(addr) => unsafe {
69                AcpiTables::from_rsdp(AcpiMemoryHandler {}, addr).unwrap()
70            },
71            BootloaderAcpiArg::Rsdt(addr) => unsafe {
72                AcpiTables::from_rsdt(AcpiMemoryHandler {}, 0, addr).unwrap()
73            },
74            BootloaderAcpiArg::Xsdt(addr) => unsafe {
75                AcpiTables::from_rsdt(AcpiMemoryHandler {}, 1, addr).unwrap()
76            },
77            BootloaderAcpiArg::NotProvided => {
78                // We search by ourselves if the bootloader decides not to provide a rsdp location.
79                let rsdp = unsafe { Rsdp::search_for_on_bios(AcpiMemoryHandler {}) };
80                match rsdp {
81                    Ok(map) => unsafe {
82                        AcpiTables::from_rsdp(AcpiMemoryHandler {}, map.physical_start()).unwrap()
83                    },
84                    Err(_) => {
85                        warn!("ACPI info not found!");
86                        return SyncAcpiTables(None);
87                    }
88                }
89            }
90        };
91
92        SyncAcpiTables(Some(acpi_tables))
93    });
94
95    acpi_tables.0.as_ref()
96}
97
98/// The platform information provided by the ACPI tables.
99///
100/// Currently, this structure contains only a limited set of fields, far fewer than those in all
101/// ACPI tables. However, the goal is to expand it properly to keep the simplicity of the OSTD code
102/// while enabling OSTD users to safely retrieve information from the ACPI tables.
103#[derive(Debug)]
104pub struct AcpiInfo {
105    /// The RTC CMOS RAM index to the century of data value; the "CENTURY" field in the FADT.
106    pub century_register: Option<NonZeroU8>,
107    /// IA-PC Boot Architecture Flags; the "IAPC_BOOT_ARCH" field in the FADT.
108    pub boot_flags: Option<IaPcBootArchFlags>,
109    /// An I/O port to reset the machine by writing the specified value.
110    pub reset_port_and_val: Option<(u16, u8)>,
111    /// A memory region that is stolen for PCI configuration space.
112    pub pci_ecam_region: Option<PciEcamRegion>,
113}
114
115/// A memory region that is stolen for PCI configuration space.
116#[derive(Debug)]
117pub struct PciEcamRegion {
118    /// The base address of the memory region.
119    pub base_address: u64,
120    /// The start of the bus number.
121    pub bus_start: u8,
122    /// The end of the bus number.
123    pub bus_end: u8,
124}
125
126/// The [`AcpiInfo`] singleton.
127pub static ACPI_INFO: Once<AcpiInfo> = Once::new();
128
129pub(in crate::arch) fn init() {
130    let mut acpi_info = AcpiInfo {
131        century_register: None,
132        boot_flags: None,
133        reset_port_and_val: None,
134        pci_ecam_region: None,
135    };
136
137    let Some(acpi_tables) = get_acpi_tables() else {
138        ACPI_INFO.call_once(|| acpi_info);
139        return;
140    };
141
142    if let Ok(fadt) = acpi_tables.find_table::<Fadt>() {
143        // A zero means that the century register does not exist.
144        acpi_info.century_register = NonZeroU8::new(fadt.century);
145        acpi_info.boot_flags = Some(fadt.iapc_boot_arch);
146        if let Ok(reset_reg) = fadt.reset_register()
147            && reset_reg.address_space == AddressSpace::SystemIo
148            && let Ok(reset_port) = reset_reg.address.try_into()
149        {
150            acpi_info.reset_port_and_val = Some((reset_port, fadt.reset_value));
151        }
152    };
153
154    if let Ok(mcfg) = acpi_tables.find_table::<Mcfg>()
155        // TODO: Support multiple PCIe segment groups instead of assuming only one
156        // PCIe segment group is in use.
157        && let Some(mcfg_entry) = mcfg.entries().first()
158    {
159        acpi_info.pci_ecam_region = Some(PciEcamRegion {
160            base_address: mcfg_entry.base_address,
161            bus_start: mcfg_entry.bus_number_start,
162            bus_end: mcfg_entry.bus_number_end,
163        });
164    }
165
166    info!("Collected information {:?}", acpi_info);
167
168    ACPI_INFO.call_once(|| acpi_info);
169}
ostd/arch/x86/kernel/acpi/mod.rs

ostd/arch/x86/kernel/acpi/
mod.rs
