[interrupt-handlers] added IDT

- added IdtEntry structure,
- created IDT static mut array, and
- made fxns to init_idt and set_idt_entry.

Signed-off-by: danbugs <[email protected]>

Author: danbugs

src/hyperlight_guest/src/idt.rs

@@ -0,0 +1,102 @@
+/*
+Copyright 2024 The Hyperlight Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+use crate::interrupt_entry::{
+    _do_excp0, _do_excp1, _do_excp10, _do_excp11, _do_excp12, _do_excp13, _do_excp15, _do_excp16,
+    _do_excp17, _do_excp18, _do_excp19, _do_excp2, _do_excp20, _do_excp3, _do_excp30, _do_excp4,
+    _do_excp5, _do_excp6, _do_excp7, _do_excp8, _do_excp9,
+};
+
+// An entry in the Interrupt Descriptor Table (IDT)
+// For reference, see page 7-20 Vol. 3A of Intel 64 and IA-32
+// Architectures Software Developer's Manual, figure 7-8
+// (i.e., https://i.imgur.com/N4rEjHj.png).
+// From the bottom, we have:
+// - offset 15..0 = offset_low
+// - segment selector 31..16 = selector
+// - 000 0 0 Interrupt Stack Table 7..0 = interrupt_stack_table_offset
+// - p dpl 0 type 15..8 = type_attr
+// - offset 31..16 = offset_mid
+// - offset 63..32 = offset_high
+// - reserved 31..0 = zero
+#[repr(C, align(16))]
+pub(crate) struct IdtEntry {
+    offset_low: u16,                  // Lower 16 bits of handler address
+    selector: u16,                    // code segment selector in GDT
+    interrupt_stack_table_offset: u8, // Interrupt Stack Table offset
+    type_attr: u8,                    // Gate type and flags
+    offset_mid: u16,                  // Middle 16 bits of handler address
+    offset_high: u32,                 // High 32 bits of handler address
+    zero: u32,                        // Reserved (always 0)
+}
+
+impl IdtEntry {
+    fn new(handler: u64) -> Self {
+        Self {
+            offset_low: (handler & 0xFFFF) as u16,
+            selector: 0x08,                  // Kernel Code Segment
+            interrupt_stack_table_offset: 0, // No interrupt stack table used
+            type_attr: 0x8E,
+            // 0x8E = 10001110b
+            // 1 00 0 1110
+            // 1 = Present
+            // 00 = Descriptor Privilege Level (0)
+            // 0 = Storage Segment (0)
+            // 1110 = Gate Type (0b1110 = 14 = 0xE)
+            // 0xE means it's an interrupt gate
+            offset_mid: ((handler >> 16) & 0xFFFF) as u16,
+            offset_high: ((handler >> 32) & 0xFFFFFFFF) as u32,
+            zero: 0,
+        }
+    }
+}
+
+// The IDT is an array of 256 IDT entries
+// (for reference, see page 7-9 Vol. 3A of Intel 64 and IA-32
+// Architectures Software Developer's Manual).
+pub(crate) static mut IDT: [IdtEntry; 256] = unsafe { core::mem::zeroed() };
+
+pub(crate) fn init_idt() {
+    set_idt_entry(0, _do_excp0); // Divide by zero
+    set_idt_entry(1, _do_excp1); // Debug
+    set_idt_entry(2, _do_excp2); // Non-maskable interrupt
+    set_idt_entry(3, _do_excp3); // Breakpoint
+    set_idt_entry(4, _do_excp4); // Overflow
+    set_idt_entry(5, _do_excp5); // Bound Range Exceeded
+    set_idt_entry(6, _do_excp6); // Invalid Opcode
+    set_idt_entry(7, _do_excp7); // Device Not Available
+    set_idt_entry(8, _do_excp8); // Double Fault
+    set_idt_entry(9, _do_excp9); // Coprocessor Segment Overrun
+    set_idt_entry(10, _do_excp10); // Invalid TSS
+    set_idt_entry(11, _do_excp11); // Segment Not Present
+    set_idt_entry(12, _do_excp12); // Stack-Segment Fault
+    set_idt_entry(13, _do_excp13); // General Protection Fault
+                                   // set_idt_entry(14, _do_excp14); // Page Fault
+    set_idt_entry(15, _do_excp15); // Reserved
+    set_idt_entry(16, _do_excp16); // x87 Floating-Point Exception
+    set_idt_entry(17, _do_excp17); // Alignment Check
+    set_idt_entry(18, _do_excp18); // Machine Check
+    set_idt_entry(19, _do_excp19); // SIMD Floating-Point Exception
+    set_idt_entry(20, _do_excp20); // Virtualization Exception
+    set_idt_entry(30, _do_excp30); // Security Exception
+}
+
+fn set_idt_entry(index: usize, handler: unsafe extern "sysv64" fn()) {
+    let handler_addr = handler as *const () as u64;
+    unsafe {
+        IDT[index] = IdtEntry::new(handler_addr);
+    }
+}

src/hyperlight_guest/src/lib.rs

@@ -53,6 +53,7 @@ pub mod error;
 pub mod logging;
 pub mod interrupt_entry;
 pub mod interrupt_handlers;
+pub mod idt;
 
 // Unresolved symbols
 ///cbindgen:ignore