feat: acpi, apic, apic timer

src/arch/x86_64/cpu.rs

@@ -4,6 +4,7 @@ use core::arch::asm;
 pub enum CpuFeaturesError {
     CpuidFeaturesNotSupported,
     InvalidPhysicalAddressWidth,
+    InvalidVirtualAddressWidth,
 }
 
 #[derive(Clone, Copy, Debug)]
@@ -12,14 +13,19 @@ pub(crate) struct CpuFeatures {
     pub nx_enabled: bool,
     pub physical_address_bits: u8,
     pub virtual_address_bits: u8,
+    pub five_level_paging_active: bool,
 }
 
+// Extended features
+const IA32_EFER: u32 = 0xC0000080;
+
 pub fn detect_features_and_enable() -> Result<CpuFeatures, CpuFeaturesError> {
     let mut features = CpuFeatures {
         nx_supported: false,
         nx_enabled: false,
         physical_address_bits: 0,
         virtual_address_bits: 0,
+        five_level_paging_active: false,
     };
 
     let cpuid_result = core::arch::x86_64::__cpuid_count(0x80000000, 0);
@@ -40,6 +46,16 @@ pub fn detect_features_and_enable() -> Result<CpuFeatures, CpuFeaturesError> {
     }
 
     features.virtual_address_bits = (cpuid_result.eax >> 8 & 0xFF) as u8;
+    features.five_level_paging_active = read_cr4() & (1 << 12) != 0;
+
+    let required_virtual_address_bits = if features.five_level_paging_active {
+        57
+    } else {
+        48
+    };
+    if features.virtual_address_bits < required_virtual_address_bits {
+        return Err(CpuFeaturesError::InvalidVirtualAddressWidth);
+    }
 
     if features.nx_supported {
         let cpuid_result = core::arch::x86_64::__cpuid_count(0x1, 0);
@@ -50,19 +66,33 @@ pub fn detect_features_and_enable() -> Result<CpuFeatures, CpuFeaturesError> {
         }
 
         // mother efer
-        let efer = unsafe { read_msr(0xC0000080) };
+        let efer = unsafe { read_msr(IA32_EFER) };
 
         unsafe {
-            write_msr(0xC0000080, efer | (1 << 11));
+            write_msr(IA32_EFER, efer | (1 << 11));
         }
 
-        features.nx_enabled = unsafe { read_msr(0xC0000080) } & (1 << 11) != 0;
+        features.nx_enabled = unsafe { read_msr(IA32_EFER) } & (1 << 11) != 0;
     }
 
     Ok(features)
 }
 
-unsafe fn read_msr(msr: u32) -> u64 {
+fn read_cr4() -> usize {
+    let value: usize;
+
+    unsafe {
+        asm!(
+            "mov {}, cr4",
+            out(reg) value,
+            options(nomem, nostack, preserves_flags),
+        );
+    }
+
+    value
+}
+
+pub(super) unsafe fn read_msr(msr: u32) -> u64 {
     let low: u32;
     let high: u32;
 
@@ -79,7 +109,7 @@ unsafe fn read_msr(msr: u32) -> u64 {
     ((high as u64) << 32) | low as u64
 }
 
-unsafe fn write_msr(msr: u32, value: u64) {
+pub(super) unsafe fn write_msr(msr: u32, value: u64) {
     unsafe {
         asm!(
             "wrmsr",