diff --git a/kernel/comps/virtio/Cargo.toml b/kernel/comps/virtio/Cargo.toml
index 4c5fb1440..a610949fb 100644
--- a/kernel/comps/virtio/Cargo.toml
+++ b/kernel/comps/virtio/Cargo.toml
@@ -24,5 +24,9 @@ component = { path = "../../libs/comp-sys/component" }
 log = "0.4"
 int-to-c-enum = { path = "../../libs/int-to-c-enum" }
 
+[features]
+all = ["cvm_guest"]
+cvm_guest = ["ostd/cvm_guest"]
+
 [lints]
 workspace = true
diff --git a/ostd/src/bus/mmio/bus.rs b/kernel/comps/virtio/src/transport/mmio/bus/bus.rs
similarity index 96%
rename from ostd/src/bus/mmio/bus.rs
rename to kernel/comps/virtio/src/transport/mmio/bus/bus.rs
index e03a20725..ab455528c 100644
--- a/ostd/src/bus/mmio/bus.rs
+++ b/kernel/comps/virtio/src/transport/mmio/bus/bus.rs
@@ -2,14 +2,12 @@
 
 //! MMIO bus.
 
-#![expect(unused_variables)]
-
 use alloc::{collections::VecDeque, fmt::Debug, sync::Arc, vec::Vec};
 
 use log::{debug, error};
+use ostd::bus::BusProbeError;
 
 use super::common_device::MmioCommonDevice;
-use crate::bus::BusProbeError;
 
 /// MMIO device trait
 pub trait MmioDevice: Sync + Send + Debug {
@@ -45,7 +43,7 @@ impl MmioBus {
     pub fn register_driver(&mut self, driver: Arc<dyn MmioDriver>) {
         debug!("Register driver:{:#x?}", driver);
         let length = self.common_devices.len();
-        for i in (0..length).rev() {
+        for _ in (0..length).rev() {
             let common_device = self.common_devices.pop_front().unwrap();
             let device_id = common_device.read_device_id().unwrap();
             let device = match driver.probe(common_device) {
diff --git a/ostd/src/bus/mmio/common_device.rs b/kernel/comps/virtio/src/transport/mmio/bus/common_device.rs
similarity index 88%
rename from ostd/src/bus/mmio/common_device.rs
rename to kernel/comps/virtio/src/transport/mmio/bus/common_device.rs
index c040f8e06..552a2f918 100644
--- a/ostd/src/bus/mmio/common_device.rs
+++ b/kernel/comps/virtio/src/transport/mmio/bus/common_device.rs
@@ -4,12 +4,11 @@
 
 use int_to_c_enum::TryFromInt;
 use log::info;
-
 #[cfg(target_arch = "x86_64")]
-use crate::arch::kernel::MappedIrqLine;
+use ostd::arch::kernel::MappedIrqLine;
 #[cfg(target_arch = "riscv64")] // TODO: Add `MappedIrqLine` support for RISC-V.
-use crate::trap::IrqLine as MappedIrqLine;
-use crate::{io::IoMem, mm::VmIoOnce, trap::IrqLine, Error, Result};
+use ostd::trap::IrqLine as MappedIrqLine;
+use ostd::{io::IoMem, mm::VmIoOnce, trap::IrqLine, Error, Result};
 
 /// A MMIO common device.
 #[derive(Debug)]
@@ -53,11 +52,6 @@ impl MmioCommonDevice {
     pub fn irq(&self) -> &IrqLine {
         &self.irq
     }
-
-    /// Returns a mutable reference to the IRQ line.
-    pub fn irq_mut(&mut self) -> &mut IrqLine {
-        &mut self.irq
-    }
 }
 
 /// Virtio MMIO version.
diff --git a/ostd/src/bus/mmio/mod.rs b/kernel/comps/virtio/src/transport/mmio/bus/mod.rs
similarity index 92%
rename from ostd/src/bus/mmio/mod.rs
rename to kernel/comps/virtio/src/transport/mmio/bus/mod.rs
index 246183854..db5a9a43e 100644
--- a/ostd/src/bus/mmio/mod.rs
+++ b/kernel/comps/virtio/src/transport/mmio/bus/mod.rs
@@ -3,18 +3,18 @@
 //! Virtio over MMIO
 
 use bus::MmioBus;
+use ostd::sync::SpinLock;
 
-use crate::sync::SpinLock;
-
-pub mod bus;
-pub mod common_device;
+#[expect(clippy::module_inception)]
+pub(super) mod bus;
+pub(super) mod common_device;
 
 /// The MMIO bus instance.
-pub static MMIO_BUS: SpinLock<MmioBus> = SpinLock::new(MmioBus::new());
+pub(super) static MMIO_BUS: SpinLock<MmioBus> = SpinLock::new(MmioBus::new());
 
-pub(crate) fn init() {
+pub(super) fn init() {
     #[cfg(target_arch = "x86_64")]
-    crate::arch::if_tdx_enabled!({
+    ostd::if_tdx_enabled!({
         // TODO: support virtio-mmio devices on TDX.
         //
         // Currently, virtio-mmio devices need to acquire sub-page MMIO regions,
@@ -28,8 +28,7 @@ pub(crate) fn init() {
 fn x86_probe() {
     use common_device::{mmio_check_magic, mmio_read_device_id, MmioCommonDevice};
     use log::debug;
-
-    use crate::{arch::kernel::IRQ_CHIP, io::IoMem, trap::IrqLine};
+    use ostd::{arch::kernel::IRQ_CHIP, io::IoMem, trap::IrqLine};
 
     // TODO: The correct method for detecting VirtIO-MMIO devices on x86_64 systems is to parse the
     // kernel command line if ACPI tables are absent [1], or the ACPI SSDT if ACPI tables are
diff --git a/kernel/comps/virtio/src/transport/mmio/device.rs b/kernel/comps/virtio/src/transport/mmio/device.rs
index 12c1297dd..cf0bc8bc1 100644
--- a/kernel/comps/virtio/src/transport/mmio/device.rs
+++ b/kernel/comps/virtio/src/transport/mmio/device.rs
@@ -7,20 +7,21 @@ use aster_rights::{ReadOp, WriteOp};
 use aster_util::{field_ptr, safe_ptr::SafePtr};
 use log::warn;
 use ostd::{
-    bus::{
-        mmio::{
-            bus::MmioDevice,
-            common_device::{MmioCommonDevice, VirtioMmioVersion},
-        },
-        pci::cfg_space::Bar,
-    },
+    bus::pci::cfg_space::Bar,
     io::IoMem,
     mm::{DmaCoherent, PAGE_SIZE},
     sync::RwLock,
     trap::IrqCallbackFunction,
 };
 
-use super::{layout::VirtioMmioLayout, multiplex::MultiplexIrq};
+use super::{
+    bus::{
+        bus::MmioDevice,
+        common_device::{MmioCommonDevice, VirtioMmioVersion},
+    },
+    layout::VirtioMmioLayout,
+    multiplex::MultiplexIrq,
+};
 use crate::{
     queue::{AvailRing, Descriptor, UsedRing},
     transport::{ConfigManager, DeviceStatus, VirtioTransport, VirtioTransportError},
@@ -36,7 +37,7 @@ pub struct VirtioMmioDevice {
 pub struct VirtioMmioTransport {
     layout: SafePtr<VirtioMmioLayout, IoMem>,
     device: Arc<VirtioMmioDevice>,
-    common_device: ostd::bus::mmio::common_device::MmioCommonDevice,
+    common_device: MmioCommonDevice,
     multiplex: Arc<RwLock<MultiplexIrq>>,
 }
 
diff --git a/kernel/comps/virtio/src/transport/mmio/driver.rs b/kernel/comps/virtio/src/transport/mmio/driver.rs
index 5dff50353..42c47904c 100644
--- a/kernel/comps/virtio/src/transport/mmio/driver.rs
+++ b/kernel/comps/virtio/src/transport/mmio/driver.rs
@@ -2,18 +2,15 @@
 
 use alloc::{sync::Arc, vec::Vec};
 
-use ostd::{
-    bus::{
-        mmio::{
-            bus::{MmioDevice, MmioDriver},
-            common_device::MmioCommonDevice,
-        },
-        BusProbeError,
-    },
-    sync::SpinLock,
-};
+use ostd::{bus::BusProbeError, sync::SpinLock};
 
-use super::device::VirtioMmioTransport;
+use super::{
+    bus::{
+        bus::{MmioDevice, MmioDriver},
+        common_device::MmioCommonDevice,
+    },
+    device::VirtioMmioTransport,
+};
 
 #[derive(Debug)]
 pub struct VirtioMmioDriver {
diff --git a/kernel/comps/virtio/src/transport/mmio/mod.rs b/kernel/comps/virtio/src/transport/mmio/mod.rs
index 2bf16e294..dc03ab335 100644
--- a/kernel/comps/virtio/src/transport/mmio/mod.rs
+++ b/kernel/comps/virtio/src/transport/mmio/mod.rs
@@ -2,18 +2,22 @@
 
 use alloc::sync::Arc;
 
-use ostd::bus::mmio::MMIO_BUS;
+use bus::MMIO_BUS;
 use spin::Once;
 
 use self::driver::VirtioMmioDriver;
 
+mod bus;
 pub mod device;
 pub mod driver;
 pub mod layout;
 pub mod multiplex;
 
 pub static VIRTIO_MMIO_DRIVER: Once<Arc<VirtioMmioDriver>> = Once::new();
+
 pub fn virtio_mmio_init() {
+    bus::init();
+
     VIRTIO_MMIO_DRIVER.call_once(|| Arc::new(VirtioMmioDriver::new()));
     MMIO_BUS
         .lock()
diff --git a/ostd/src/bus/mod.rs b/ostd/src/bus/mod.rs
index f22a58363..fc9f460aa 100644
--- a/ostd/src/bus/mod.rs
+++ b/ostd/src/bus/mod.rs
@@ -2,7 +2,6 @@
 
 //! Bus operations
 
-pub mod mmio;
 pub mod pci;
 
 /// An error that occurs during bus probing.
@@ -17,5 +16,4 @@ pub enum BusProbeError {
 /// Initializes the bus
 pub(crate) fn init() {
     pci::init();
-    mmio::init();
 }