fix: proper firecracker shutdown

.github/workflows/ci.yml

@@ -414,20 +414,19 @@ jobs:
       with:
         repo: hermitcore/rusty-loader
         file: rusty-loader-x86_64-fc
-    - name: Download firecracker
-      uses: dsaltares/fetch-gh-release-asset@1.1.1
-      with:
-        repo: firecracker-microvm/firecracker
-        version: tags/v1.4.1
-        file: firecracker-v1.4.1-x86_64.tgz
-        target: 'firecracker-x86_64.tgz'
     - name: Install firecracker
       run: |
-        tar xzvf firecracker-x86_64.tgz --one-top-level=fc --strip-components 1
+        # https://github.com/firecracker-microvm/firecracker/blob/7c5fc8707f26c4244d48a747631ab0fb31fc4c39/docs/getting-started.md#getting-a-firecracker-binary
+        ARCH="$(uname -m)"
+        release_url="https://github.com/firecracker-microvm/firecracker/releases"
+        latest=$(basename $(curl -fsSLI -o /dev/null -w  %{url_effective} ${release_url}/latest))
+        curl -L ${release_url}/download/${latest}/firecracker-${latest}-${ARCH}.tgz \
+        | tar -xz
+
+        # Rename the binary to "firecracker"
+        mv release-${latest}-$(uname -m)/firecracker-${latest}-${ARCH} firecracker
+        echo "$PWD" >> $GITHUB_PATH
     - name: Build minimal profile (debug)
       run: cargo build -Zbuild-std=std,panic_abort --target x86_64-unknown-hermit --no-default-features --package hello_world
     - name: Test debug profile (Firecracker)
-      run: |
-        ./fc/firecracker-v1.4.1-x86_64 --no-api --config-file ./kernel/fc-config.json &
-        sleep 1
-        kill -KILL $(pidof firecracker-v1.4.1-x86_64)
+      run: firecracker --no-api --config-file ./kernel/fc-config.json

src/arch/x86_64/kernel/processor.rs

@@ -11,12 +11,16 @@ use core::sync::atomic::{AtomicU64, Ordering};
 use core::{fmt, u32};
 
 use hermit_entry::boot_info::PlatformInfo;
-use hermit_sync::{without_interrupts, Lazy};
+use hermit_sync::Lazy;
 use qemu_exit::QEMUExit;
 use x86::bits64::segmentation;
 use x86::controlregs::*;
 use x86::cpuid::*;
 use x86::msr::*;
+use x86_64::instructions::interrupts::int3;
+use x86_64::instructions::tables::lidt;
+use x86_64::structures::DescriptorTablePointer;
+use x86_64::VirtAddr;
 
 #[cfg(feature = "acpi")]
 use crate::arch::x86_64::kernel::acpi;
@@ -975,6 +979,23 @@ pub fn halt() {
 	}
 }
 
+/// Causes a triple fault.
+///
+/// Triple faults cause CPU resets.
+/// On KVM, this results in `KVM_EXIT_SHUTDOWN`.
+/// This is the preferred way of shutting down the CPU on firecracker.
+///
+/// See [Triple Faulting the CPU](http://www.rcollins.org/Productivity/TripleFault.html).
+fn triple_fault() -> ! {
+	let idt = DescriptorTablePointer {
+		limit: 0,
+		base: VirtAddr::zero(),
+	};
+	unsafe { lidt(&idt) };
+	int3();
+	unreachable!()
+}
+
 /// Shutdown the system
 pub fn shutdown() -> ! {
 	info!("Shutting down system");
@@ -994,14 +1015,13 @@ pub fn shutdown() -> ! {
 		Ok(_never) => unreachable!(),
 		Err(()) => {
 			match boot_info().platform_info {
-				PlatformInfo::LinuxBootParams { .. } => without_interrupts(|| loop {
-					halt();
-				}),
-				_ => {
+				PlatformInfo::LinuxBootParams { .. } => triple_fault(),
+				PlatformInfo::Multiboot { .. } => {
 					// Try QEMU's debug exit
 					let exit_handler = qemu_exit::X86::new(0xf4, 3);
 					exit_handler.exit_success()
 				}
+				PlatformInfo::Uhyve { .. } => todo!(),
 			}
 		}
 	}