diff --git a/src/dragonball/src/kvm_context.rs b/src/dragonball/src/kvm_context.rs
index f4a840860..ce4583458 100644
--- a/src/dragonball/src/kvm_context.rs
+++ b/src/dragonball/src/kvm_context.rs
@@ -228,7 +228,7 @@ mod tests {
         assert!(c.max_memslots >= 32);
 
         let kvm = Kvm::new().unwrap();
-        let f = unsafe { File::from_raw_fd(kvm.as_raw_fd()) };
+        let f = std::mem::ManuallyDrop::new(unsafe { File::from_raw_fd(kvm.as_raw_fd()) });
         let m1 = f.metadata().unwrap();
         let m2 = File::open("/dev/kvm").unwrap().metadata().unwrap();
 
diff --git a/src/dragonball/src/vcpu/vcpu_impl.rs b/src/dragonball/src/vcpu/vcpu_impl.rs
index ff3f9e44f..f6c1c2d4c 100644
--- a/src/dragonball/src/vcpu/vcpu_impl.rs
+++ b/src/dragonball/src/vcpu/vcpu_impl.rs
@@ -758,13 +758,11 @@ impl Drop for Vcpu {
 
 #[cfg(test)]
 pub mod tests {
-    use std::os::unix::io::AsRawFd;
     use std::sync::mpsc::{channel, Receiver};
     use std::sync::Mutex;
 
     use arc_swap::ArcSwap;
     use dbs_device::device_manager::IoManager;
-    use kvm_ioctls::Kvm;
     use lazy_static::lazy_static;
     use test_utils::skip_if_not_root;
 
@@ -812,12 +810,8 @@ pub mod tests {
 
     #[cfg(target_arch = "x86_64")]
     fn create_vcpu() -> (Vcpu, Receiver<VcpuStateEvent>) {
-        // Call for kvm too frequently would cause error in some host kernel.
-        std::thread::sleep(std::time::Duration::from_millis(5));
-
-        let kvm = Kvm::new().unwrap();
-        let vm = Arc::new(kvm.create_vm().unwrap());
-        let kvm_context = KvmContext::new(Some(kvm.as_raw_fd())).unwrap();
+        let kvm_context = KvmContext::new(None).unwrap();
+        let vm = kvm_context.kvm().create_vm().unwrap();
         let vcpu_fd = Arc::new(vm.create_vcpu(0).unwrap());
         let io_manager = IoManagerCached::new(Arc::new(ArcSwap::new(Arc::new(IoManager::new()))));
         let supported_cpuid = kvm_context
diff --git a/src/dragonball/src/vcpu/vcpu_manager.rs b/src/dragonball/src/vcpu/vcpu_manager.rs
index 22c90f2e2..2b076cd5b 100644
--- a/src/dragonball/src/vcpu/vcpu_manager.rs
+++ b/src/dragonball/src/vcpu/vcpu_manager.rs
@@ -1062,7 +1062,6 @@ mod tests {
     fn get_vm() -> Vm {
         let instance_info = Arc::new(RwLock::new(InstanceInfo::default()));
         let epoll_manager = EpollManager::default();
-        std::thread::sleep(std::time::Duration::from_millis(200));
         let mut vm = Vm::new(None, instance_info, epoll_manager).unwrap();
         let vm_config = VmConfigInfo {
             vcpu_count: 1,
@@ -1111,7 +1110,6 @@ mod tests {
         skip_if_not_root!();
         let instance_info = Arc::new(RwLock::new(InstanceInfo::default()));
         let epoll_manager = EpollManager::default();
-        std::thread::sleep(std::time::Duration::from_millis(200));
         let mut vm = Vm::new(None, instance_info, epoll_manager).unwrap();
         let vm_config = VmConfigInfo {
             vcpu_count: 1,