Use sealed trait pattern to avoid private trait in public interface w…

…arning
hermit-os · Jan 24, 2025 · e5d8927 · e5d8927
1 parent 0a49cd9
commit e5d8927
Show file tree

Hide file tree

Showing 4 changed files with 56 additions and 29 deletions.
diff --git a/src/linux/x86_64/kvm_cpu.rs b/src/linux/x86_64/kvm_cpu.rs
@@ -15,7 +15,9 @@ use crate::{
 	stats::{CpuStats, VmExit},
 	vcpu::{VcpuStopReason, VirtualCPU},
 	virtio::*,
-	vm::{KernelInfo, VirtualizationBackend, VmPeripherals},
+	vm::{
+		internal::VirtualizationBackendInternal, KernelInfo, VirtualizationBackend, VmPeripherals,
+	},
 	HypervisorResult,
 };
 
@@ -34,7 +36,7 @@ pub struct KvmVm {
 	vm_fd: VmFd,
 	peripherals: Arc<VmPeripherals>,
 }
-impl VirtualizationBackend for KvmVm {
+impl VirtualizationBackendInternal for KvmVm {
 	type VCPU = KvmCpu;
 	const NAME: &str = "KvmVm";
 
@@ -154,6 +156,10 @@ impl VirtualizationBackend for KvmVm {
 	}
 }
 
+impl VirtualizationBackend for KvmVm {
+	type BACKEND = Self;
+}
+
 pub struct KvmCpu {
 	id: u32,
 	vcpu: VcpuFd,

diff --git a/src/macos/aarch64/vcpu.rs b/src/macos/aarch64/vcpu.rs
@@ -20,14 +20,14 @@ use crate::{
 	params::Params,
 	stats::{CpuStats, VmExit},
 	vcpu::{VcpuStopReason, VirtualCPU},
-	vm::{KernelInfo, VirtualizationBackend, VmPeripherals},
+	vm::{KernelInfo, VirtualizationBackend, internal::VirtualizationBackendInternal, VmPeripherals},
 	HypervisorResult,
 };
 
 pub struct XhyveVm {
 	peripherals: Arc<VmPeripherals>,
 }
-impl VirtualizationBackend for XhyveVm {
+impl VirtualizationBackendInternal for XhyveVm {
 	type VCPU = XhyveCpu;
 	const NAME: &str = "XhyveVm";
 
@@ -67,6 +67,10 @@ impl VirtualizationBackend for XhyveVm {
 	}
 }
 
+impl VirtualizationBackend for XhyveVm {
+	type BACKEND = Self;
+}
+
 pub struct XhyveCpu {
 	id: u32,
 	vcpu: xhypervisor::VirtualCpu,

diff --git a/src/macos/x86_64/vcpu.rs b/src/macos/x86_64/vcpu.rs
@@ -38,7 +38,7 @@ use crate::{
 	params::Params,
 	stats::{CpuStats, VmExit},
 	vcpu::{VcpuStopReason, VirtualCPU},
-	vm::{UhyveVm, VirtualizationBackend},
+	vm::{internal::VirtualizationBackendInternal, UhyveVm, VirtualizationBackend},
 	HypervisorResult,
 };
 
@@ -158,7 +158,7 @@ static CAP_EXIT: LazyLock<u64> = LazyLock::new(|| {
 });
 
 pub struct XhyveVm {}
-impl VirtualizationBackend for XhyveVm {
+impl VirtualizationBackendInternal for XhyveVm {
 	type VCPU = XhyveCpu;
 	const NAME: &str = "XhyveVm";
 
@@ -194,6 +194,10 @@ impl VirtualizationBackend for XhyveVm {
 	}
 }
 
+impl VirtualizationBackend for XhyveVm {
+	type BACKEND = Self;
+}
+
 pub struct XhyveCpu {
 	id: u32,
 	vcpu: xhypervisor::VirtualCpu,

diff --git a/src/vm.rs b/src/vm.rs
@@ -4,7 +4,6 @@ use std::{
 	num::NonZeroU32,
 	os::unix::prelude::JoinHandleExt,
 	path::PathBuf,
-	str,
 	sync::{Arc, Barrier, Mutex},
 	thread,
 	time::SystemTime,
@@ -15,6 +14,7 @@ use hermit_entry::{
 	boot_info::{BootInfo, HardwareInfo, LoadInfo, PlatformInfo, RawBootInfo, SerialPortBase},
 	elf::{KernelObject, LoadedKernel, ParseKernelError},
 };
+use internal::VirtualizationBackendInternal;
 use log::error;
 use thiserror::Error;
 use uhyve_interface::GuestPhysAddr;
@@ -53,24 +53,37 @@ pub type DefaultBackend = crate::linux::x86_64::kvm_cpu::KvmVm;
 #[cfg(target_os = "macos")]
 pub type DefaultBackend = crate::macos::XhyveVm;
 
-/// Trait marking a interface for creating (accelerated) VMs.
-pub trait VirtualizationBackend: Sized {
-	type VCPU: 'static + VirtualCPU;
-	const NAME: &str;
-
-	/// Create a new CPU object
-	fn new_cpu(
-		&self,
-		id: u32,
-		kernel_info: Arc<KernelInfo>,
-		enable_stats: bool,
-	) -> HypervisorResult<Self::VCPU>;
-
-	fn new(
-		memory: &MmapMemory,
-		peripherals: Arc<VmPeripherals>,
-		params: &Params,
-	) -> HypervisorResult<Self>;
+pub(crate) mod internal {
+	use crate::{
+		mem::MmapMemory,
+		vm::{KernelInfo, Params, VirtualCPU, VmPeripherals},
+		HypervisorResult,
+	};
+	use std::sync::Arc;
+
+	/// Trait marking a interface for creating (accelerated) VMs.
+	pub trait VirtualizationBackendInternal: Sized {
+		type VCPU: 'static + VirtualCPU;
+		const NAME: &str;
+
+		/// Create a new CPU object
+		fn new_cpu(
+			&self,
+			id: u32,
+			kernel_info: Arc<KernelInfo>,
+			enable_stats: bool,
+		) -> HypervisorResult<Self::VCPU>;
+
+		fn new(
+			memory: &MmapMemory,
+			peripherals: Arc<VmPeripherals>,
+			params: &Params,
+		) -> HypervisorResult<Self>;
+	}
+}
+
+pub trait VirtualizationBackend {
+	type BACKEND: internal::VirtualizationBackendInternal;
 }
 
 #[derive(Debug, Clone)]
@@ -106,7 +119,7 @@ pub(crate) struct KernelInfo {
 }
 
 pub struct UhyveVm<VirtBackend: VirtualizationBackend> {
-	pub(crate) vcpus: Vec<VirtBackend::VCPU>,
+	pub(crate) vcpus: Vec<<VirtBackend::BACKEND as VirtualizationBackendInternal>::VCPU>,
 	pub(crate) peripherals: Arc<VmPeripherals>,
 	pub(crate) kernel_info: Arc<KernelInfo>,
 }
@@ -166,7 +179,7 @@ impl<VirtBackend: VirtualizationBackend> UhyveVm<VirtBackend> {
 		});
 
 		let virt_backend =
-			VirtBackend::new(&peripherals.mem, peripherals.clone(), &kernel_info.params)?;
+			VirtBackend::BACKEND::new(&peripherals.mem, peripherals.clone(), &kernel_info.params)?;
 
 		let cpu_count = kernel_info.params.cpu_count.get();
 
@@ -225,7 +238,7 @@ impl<VirtBackend: VirtualizationBackend> UhyveVm<VirtBackend> {
 				let barrier = barrier.clone();
 				let local_cpu_affinity = cpu_affinity
 					.as_ref()
-					.and_then(|core_ids| core_ids.get(cpu_id as usize).copied());
+					.and_then(|core_ids| core_ids.get(cpu_id).copied());
 
 				thread::spawn(move || {
 					debug!("Create thread for CPU {}", cpu_id);
@@ -307,7 +320,7 @@ d?"
 
 impl<VirtIf: VirtualizationBackend> fmt::Debug for UhyveVm<VirtIf> {
 	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-		f.debug_struct(&format!("UhyveVm<{}>", VirtIf::NAME))
+		f.debug_struct(&format!("UhyveVm<{}>", VirtIf::BACKEND::NAME))
 			.field("entry_point", &self.kernel_info.entry_point)
 			.field("stack_address", &self.kernel_info.stack_address)
 			.field("mem", &self.peripherals.mem)