4 files changed, 127 insertions, 0 deletions
diff --git a/kernel/src/interrupts/apic.rs b/kernel/src/interrupts/apic.rs
new file mode 100644
index 0000000..519caf2
--- /dev/null
+++ b/kernel/src/interrupts/apic.rs
@@ -0,0 +1,121 @@
+use x86_64::registers::model_specific::Msr;
+
+#[cfg(target_arch = "x86_64")]
+const APIC_FLAG: u64 = 0x0800;
+const APIC_BASE_MSR: u32 = 0x1b;
+
+pub fn is_x2apic() -> bool {
+    let info: u32;
+    unsafe {
+        asm!("cpuid" : "={ecx}" (info) : "{eax}" (1) : "memory");
+    }
+    info & (1 << 21) != 0
+}
+
+pub fn is_apic() -> bool {
+    let info: u32;
+    unsafe {
+        asm!("cpuid" : "={edx}" (info) : "{eax}" (1) : "memory");
+    }
+    info & (1 << 9) != 0
+}
+
+pub fn set_apic_base(v: u64) {
+    unsafe { Msr::new(APIC_BASE_MSR).write(v) }
+}
+
+#[repr(C)]
+pub struct InterruptCommand {
+    low: u32,
+    _rsv: [u32; 3],
+    high: u32
+}
+
+#[repr(isize)]
+pub enum ApicRegister {
+    ApicId=8,
+    ApicVer=12,
+    TaskPriority=32,
+    ArbitrationPriority=36,
+    ProcessorPriority=40,
+    EndOfInterrupt=44,
+    LogicalDst=52,
+    DstFmt=56,
+    SpuriousInterruptVec=60,
+    InService=64,
+    TriggerMode=96,
+    InterruptRequest=128,
+    ErrorStatus=160,
+    InterruptCommand=192,
+    InterruptCommandHigh=196,
+    LvtTimer=200,
+    LvtThermalSensor=204,
+    LvtPerformanceMonitor=208,
+    LvtLint1=212,
+    LvtError=220,
+    TimerInitialCount=224,
+    TimerCurrentCount=228,
+    TimerDivideConfig=248,
+    ExtApicFeature=256,
+    ExtApicControl=260,
+    SpecificEndOfInterrupt=264,
+    InterruptEnable=288,
+    ExtInterruptLocalVectorTable=320,
+}
+
+#[repr(C)]
+pub struct ApicRegisters {
+    regs32: *mut [u32; 1024],
+}
+
+impl ApicRegisters {
+    fn from_base_apic(base_apic: u64) -> Self {
+        Self { regs32:
+            ((base_apic >> 12) & 0xfffffffff) as *mut [u32; 1024]
+        }
+    }
+
+    fn ptr(&self) -> *const u32 { self.regs32 as *const u32 }
+    fn ptr_mut(&mut self) -> *mut u32 { self.regs32 as *mut u32 }
+
+    pub fn get(&self, register: ApicRegister) -> u32 {
+        unsafe { self.ptr().offset(register as isize).read_volatile() }
+    }
+
+    pub fn set(&mut self, register: ApicRegister, val: u32) {
+        unsafe { self.ptr_mut().offset(register as isize).write_volatile(val) }
+    }
+
+    pub fn set_interrupt_command(&mut self, dst: u8, v: u8) {
+        let (dst, v): (u32, u32) = (dst.into(), v.into());
+        self.set(ApicRegister::InterruptCommandHigh, dst << 24);
+        self.set(ApicRegister::InterruptCommand, v)
+    }
+}
+
+pub struct Apic {
+    base_apic: u64,
+    regs: ApicRegisters,
+}
+
+impl Apic {
+    pub fn new() -> Option<Self> {
+        use core::fmt::Write;
+        let mut stdout = crate::io::vga_text::OStream::new();
+        stdout.clear();
+
+        if !is_apic() { return None; }
+        let mut base_apic = unsafe { Msr::new(APIC_BASE_MSR).read() };
+        let mut regs = ApicRegisters::from_base_apic(base_apic);
+
+        let spurious = regs.get(ApicRegister::SpuriousInterruptVec) | 0x1ff;
+
+        unsafe { Msr::new(APIC_BASE_MSR).write(base_apic | APIC_FLAG) };
+
+        regs.set(ApicRegister::SpuriousInterruptVec, spurious);
+
+        Some(Self {
+            base_apic, regs
+        })
+    }
+}
diff --git a/kernel/src/interrupts/mod.rs b/kernel/src/interrupts/mod.rs
index 076c61c..bc313b8 100644
--- a/kernel/src/interrupts/mod.rs
+++ b/kernel/src/interrupts/mod.rs
@@ -1,3 +1,4 @@
+pub mod apic;
 pub mod exceptions;
 pub mod gdt;
 pub mod idt;
diff --git a/kernel/src/lib.rs b/kernel/src/lib.rs
index 8ab660d..adf14b4 100644
--- a/kernel/src/lib.rs
+++ b/kernel/src/lib.rs
@@ -3,6 +3,7 @@
 #![feature(custom_test_frameworks)]
 #![feature(abi_x86_interrupt)]
 #![feature(panic_info_message)]
+#![feature(asm)]
 #![test_runner(crate::testing::serial_test_runner)]
 #![reexport_test_harness_main = "test_main"]
 #![no_std]
diff --git a/kernel/src/main.rs b/kernel/src/main.rs
index bb1dcec..1613292 100644
--- a/kernel/src/main.rs
+++ b/kernel/src/main.rs
@@ -3,6 +3,7 @@
 #![feature(custom_test_frameworks)]
 #![feature(abi_x86_interrupt)]
 #![feature(panic_info_message)]
+#![feature(asm)]
 #![test_runner(crate::testing::test_runner)]
 #![no_std]
 
@@ -18,6 +19,9 @@ pub use io::{qemu, serial, vga_text};
 #[no_mangle]
 extern "C" fn _start() -> ! {
     kernel::init();
+
+    let apic = interrupts::apic::Apic::new();
+
     if cfg!(test) {
         qemu::exit_qemu(qemu::QemuExitCode::Success);
     }