[interrupt-handlers] added IDTR

- made IDTR structure to house the IDT,
- made load_idt fxn that uses global_asm's lidt to load the IDT, and
- added fxn calls to entrypoint to init_idt and load_idt (location debatable?).

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

Author: danbugs

src/hyperlight_guest/src/entrypoint.rs

@@ -30,6 +30,8 @@ use crate::{
     __security_cookie, HEAP_ALLOCATOR, MIN_STACK_ADDRESS, OS_PAGE_SIZE, OUTB_PTR,
     OUTB_PTR_WITH_CONTEXT, P_PEB, RUNNING_MODE,
 };
+use crate::idt::init_idt;
+use crate::idtr::load_idt;
 
 #[inline(never)]
 pub fn halt() {
@@ -86,6 +88,10 @@ pub extern "win64" fn entrypoint(peb_address: u64, seed: u64, ops: u64, max_log_
             let peb_ptr = P_PEB.unwrap();
             __security_cookie = peb_address ^ seed;
 
+            // Set up IDT
+            init_idt();
+            load_idt();
+
             let srand_seed = ((peb_address << 8 ^ seed >> 4) >> 32) as u32;
 
             // Set the seed for the random number generator for C code using rand;

src/hyperlight_guest/src/idtr.rs

@@ -0,0 +1,50 @@
+/*
+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 core::arch::global_asm;
+use core::ptr::addr_of;
+use crate::idt::{IdtEntry, IDT};
+
+global_asm!(
+    "
+    .global lidt
+    lidt:
+        # SysV64 calling convention: first argument (IDTR) is in RDI
+        lidt [rdi]  # Load IDT from memory address in RDI
+        ret
+    "
+);
+
+extern "sysv64" {
+    fn lidt(idt_ptr: *const Idtr);
+}
+
+
+// The location of the IDT is stored in the IDTR.
+#[repr(C)]
+struct Idtr {
+    limit: u16,
+    base: u64,
+}
+
+pub(crate) unsafe fn load_idt() {
+    let idt_ptr = Idtr {
+        limit: (size_of::<[IdtEntry; 256]>() - 1) as u16,
+        base: addr_of!(IDT) as *const _ as u64,
+    };
+
+    lidt(&idt_ptr);
+}

src/hyperlight_guest/src/lib.rs

@@ -54,6 +54,7 @@ pub mod logging;
 pub mod interrupt_entry;
 pub mod interrupt_handlers;
 pub mod idt;
+pub mod idtr;
 
 // Unresolved symbols
 ///cbindgen:ignore