Implement the multiprocessor wakeup mechanism. (#225)

acpi/src/handler.rs

@@ -1,4 +1,8 @@
-use core::{fmt, ops::Deref, ptr::NonNull};
+use core::{
+    fmt,
+    ops::{Deref, DerefMut},
+    ptr::NonNull,
+};
 
 /// Describes a physical mapping created by `AcpiHandler::map_physical_region` and unmapped by
 /// `AcpiHandler::unmap_physical_region`. The region mapped must be at least `size_of::<T>()`
@@ -91,6 +95,15 @@ where
     }
 }
 
+impl<H, T> DerefMut for PhysicalMapping<H, T>
+where
+    H: AcpiHandler,
+{
+    fn deref_mut(&mut self) -> &mut T {
+        unsafe { self.virtual_start.as_mut() }
+    }
+}
+
 impl<H, T> Drop for PhysicalMapping<H, T>
 where
     H: AcpiHandler,

acpi/src/madt.rs

@@ -1,5 +1,6 @@
 use crate::{
     sdt::{ExtendedField, SdtHeader, Signature},
+    AcpiError,
     AcpiTable,
 };
 use bit_field::BitField;
@@ -21,6 +22,7 @@ pub enum MadtError {
     InvalidLocalNmiLine,
     MpsIntiInvalidPolarity,
     MpsIntiInvalidTriggerMode,
+    WakeupApsTimeout,
 }
 
 /// Represents the MADT - this contains the MADT header fields. You can then iterate over a `Madt`
@@ -49,6 +51,18 @@ unsafe impl AcpiTable for Madt {
 }
 
 impl Madt {
+    pub fn get_mpwk_mailbox_addr(&self) -> Result<u64, AcpiError> {
+        for entry in self.entries() {
+            match entry {
+                MadtEntry::MultiprocessorWakeup(entry) => {
+                    return Ok(entry.mailbox_address);
+                }
+                _ => {}
+            }
+        }
+        Err(AcpiError::InvalidMadt(MadtError::UnexpectedEntry))
+    }
+
     #[cfg(feature = "allocator_api")]
     pub fn parse_interrupt_model_in<'a, A>(
         &self,
@@ -102,21 +116,18 @@ impl Madt {
     where
         A: core::alloc::Allocator + Clone,
     {
-        use crate::{
-            platform::{
-                interrupt::{
-                    Apic,
-                    InterruptSourceOverride,
-                    IoApic,
-                    LocalInterruptLine,
-                    NmiLine,
-                    NmiProcessor,
-                    NmiSource,
-                },
-                Processor,
-                ProcessorState,
+        use crate::platform::{
+            interrupt::{
+                Apic,
+                InterruptSourceOverride,
+                IoApic,
+                LocalInterruptLine,
+                NmiLine,
+                NmiProcessor,
+                NmiSource,
             },
-            AcpiError,
+            Processor,
+            ProcessorState,
         };
 
         let mut local_apic_address = self.local_apic_address as u64;
@@ -630,6 +641,36 @@ pub struct MultiprocessorWakeupEntry {
     pub mailbox_address: u64,
 }
 
+#[derive(Debug, PartialEq, Eq)]
+pub enum MpProtectedModeWakeupCommand {
+    Noop = 0,
+    Wakeup = 1,
+    Sleep = 2,
+    AcceptPages = 3,
+}
+
+impl From<u16> for MpProtectedModeWakeupCommand {
+    fn from(value: u16) -> Self {
+        match value {
+            0 => MpProtectedModeWakeupCommand::Noop,
+            1 => MpProtectedModeWakeupCommand::Wakeup,
+            2 => MpProtectedModeWakeupCommand::Sleep,
+            3 => MpProtectedModeWakeupCommand::AcceptPages,
+            _ => panic!("Invalid value for MpProtectedModeWakeupCommand"),
+        }
+    }
+}
+
+#[repr(C)]
+pub struct MultiprocessorWakeupMailbox {
+    pub command: u16,
+    _reserved: u16,
+    pub apic_id: u32,
+    pub wakeup_vector: u64,
+    pub reserved_for_os: [u64; 254],
+    reserved_for_firmware: [u64; 256],
+}
+
 #[cfg(feature = "allocator_api")]
 fn parse_mps_inti_flags(flags: u16) -> crate::AcpiResult<(Polarity, TriggerMode)> {
     let polarity = match flags.get_bits(0..2) {

acpi/src/platform/mod.rs

@@ -3,15 +3,15 @@ pub mod interrupt;
 use crate::{
     address::GenericAddress,
     fadt::Fadt,
-    madt::Madt,
+    madt::{Madt, MadtError, MpProtectedModeWakeupCommand, MultiprocessorWakeupMailbox},
     AcpiError,
     AcpiHandler,
     AcpiResult,
     AcpiTables,
     ManagedSlice,
     PowerProfile,
 };
-use core::alloc::Allocator;
+use core::{alloc::Allocator, mem, ptr};
 use interrupt::InterruptModel;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -132,3 +132,63 @@ where
         Ok(PlatformInfo { power_profile, interrupt_model, processor_info, pm_timer })
     }
 }
+
+/// Wakes up Application Processors (APs) using the Multiprocessor Wakeup Mailbox mechanism.
+///
+/// For Intel processors, the execution environment is:
+/// - Interrupts must be disabled.
+/// - RFLAGES.IF set to 0.
+/// - Long mode enabled.
+/// - Paging mode is enabled and physical memory for waking vector is identity mapped (virtual address equals physical address).
+/// - Waking vector must be contained within one physical page.
+/// - Selectors are set to flat and otherwise not used.
+pub fn wakeup_aps<H>(
+    tables: &AcpiTables<H>,
+    handler: H,
+    apic_id: u32,
+    wakeup_vector: u64,
+    timeout_loops: u64,
+) -> Result<(), AcpiError>
+where
+    H: AcpiHandler,
+{
+    let madt = tables.find_table::<Madt>()?;
+    let mailbox_addr = madt.get_mpwk_mailbox_addr()?;
+    let mut mpwk_mapping = unsafe {
+        handler.map_physical_region::<MultiprocessorWakeupMailbox>(
+            mailbox_addr as usize,
+            mem::size_of::<MultiprocessorWakeupMailbox>(),
+        )
+    };
+
+    // Reset command
+    unsafe {
+        ptr::write_volatile(&mut mpwk_mapping.command, MpProtectedModeWakeupCommand::Noop as u16);
+    }
+
+    // Fill the mailbox
+    mpwk_mapping.apic_id = apic_id;
+    mpwk_mapping.wakeup_vector = wakeup_vector;
+    unsafe {
+        ptr::write_volatile(&mut mpwk_mapping.command, MpProtectedModeWakeupCommand::Wakeup as u16);
+    }
+
+    // Wait to join
+    let mut loops = 0;
+    let mut command = MpProtectedModeWakeupCommand::Wakeup;
+    while command != MpProtectedModeWakeupCommand::Noop {
+        if loops >= timeout_loops {
+            return Err(AcpiError::InvalidMadt(MadtError::WakeupApsTimeout));
+        }
+        // SAFETY: The caller must ensure that the provided `handler` correctly handles these
+        // operations and that the specified `mailbox_addr` is valid.
+        unsafe {
+            command = ptr::read_volatile(&mpwk_mapping.command).into();
+        }
+        core::hint::spin_loop();
+        loops += 1;
+    }
+    drop(mpwk_mapping);
+
+    Ok(())
+}