From c5b8eae77e67c47e411024bad7382be12381413e Mon Sep 17 00:00:00 2001
From: Chen Chengjun <chenchengjun.ccj@antgroup.com>
Date: Mon, 3 Mar 2025 14:32:19 +0800
Subject: [PATCH] Make the IRQ state within the trap correct
---
ostd/src/arch/x86/trap/mod.rs | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/ostd/src/arch/x86/trap/mod.rs b/ostd/src/arch/x86/trap/mod.rs
index fe570d3c..500783d0 100644
--- a/ostd/src/arch/x86/trap/mod.rs
+++ b/ostd/src/arch/x86/trap/mod.rs
@@ -26,6 +26,7 @@ use log::debug;
use super::ex_table::ExTable;
use crate::{
+ arch::irq::{disable_local, enable_local},
cpu::{CpuException, CpuExceptionInfo, PageFaultErrorCode},
cpu_local_cell,
mm::{
@@ -220,16 +221,38 @@ pub fn is_kernel_interrupted() -> bool {
/// Handle traps (only from kernel).
#[no_mangle]
extern "sysv64" fn trap_handler(f: &mut TrapFrame) {
+ fn enable_local_if(cond: bool) {
+ if cond {
+ enable_local();
+ }
+ }
+
+ fn disable_local_if(cond: bool) {
+ if cond {
+ disable_local();
+ }
+ }
+
+ // The IRQ state before trapping. We need to ensure that the IRQ state
+ // during exception handling is consistent with the state before the trap.
+ let was_irq_enabled =
+ f.rflags as u64 & x86_64::registers::rflags::RFlags::INTERRUPT_FLAG.bits() > 0;
+
match CpuException::to_cpu_exception(f.trap_num as u16) {
#[cfg(feature = "cvm_guest")]
Some(CpuException::VIRTUALIZATION_EXCEPTION) => {
let ve_info = tdcall::get_veinfo().expect("#VE handler: fail to get VE info\n");
+ // We need to enable interrupts only after `tdcall::get_veinfo` is called
+ // to avoid nested `#VE`s.
+ enable_local_if(was_irq_enabled);
let mut trapframe_wrapper = TrapFrameWrapper(&mut *f);
handle_virtual_exception(&mut trapframe_wrapper, &ve_info);
*f = *trapframe_wrapper.0;
+ disable_local_if(was_irq_enabled);
}
Some(CpuException::PAGE_FAULT) => {
let page_fault_addr = x86_64::registers::control::Cr2::read_raw();
+ enable_local_if(was_irq_enabled);
// The actual user space implementation should be responsible
// for providing mechanism to treat the 0 virtual address.
if (0..MAX_USERSPACE_VADDR).contains(&(page_fault_addr as usize)) {
@@ -237,8 +260,10 @@ extern "sysv64" fn trap_handler(f: &mut TrapFrame) {
} else {
handle_kernel_page_fault(f, page_fault_addr);
}
+ disable_local_if(was_irq_enabled);
}
Some(exception) => {
+ enable_local_if(was_irq_enabled);
panic!(
"cannot handle kernel CPU exception: {:?}, trapframe: {:?}",
exception, f