diff --git a/src/vmm/ept.rs b/src/vmm/ept.rs
new file mode 100644
index 0000000..1827b96
--- /dev/null
+++ b/src/vmm/ept.rs
@@ -0,0 +1,30 @@
+use bitfield::bitfield;
+use x86_64::PhysAddr;
+
+bitfield! {
+    pub struct EntryBase(u64);
+    impl Debug;
+
+    pub read, set_read: 0;
+    pub write, set_write: 1;
+    pub exec_super, set_exec_super: 2;
+    pub typ, set_typ: 5, 3;
+    pub ignore_pat, set_ignore_pat: 6;
+    pub map_memory, set_map_memory: 7;
+    pub accessed, set_accessed: 8;
+    pub dirty, set_dirty: 9;
+    pub exec_user, set_exec_user: 10;
+    pub phys, set_phys: 63, 12;
+}
+
+impl EntryBase {
+    pub fn present(&self) -> bool {
+        self.read() || self.write() || self.exec_super()
+    }
+
+    pub fn address(&self) -> PhysAddr {
+        PhysAddr::new(self.phys() << 12)
+    }
+
+    pub fn new_map_table() {}
+}
diff --git a/src/vmm/mod.rs b/src/vmm/mod.rs
index 68f9713..88b8b76 100644
--- a/src/vmm/mod.rs
+++ b/src/vmm/mod.rs
@@ -1,3 +1,4 @@
+pub mod ept;
 pub mod error;
 pub mod register;
 pub mod support;
diff --git a/src/vmm/vcpu.rs b/src/vmm/vcpu.rs
index 52d50bd..84ef83e 100644
--- a/src/vmm/vcpu.rs
+++ b/src/vmm/vcpu.rs
@@ -351,9 +351,11 @@ impl VCpu {
             result == 0
         };
 
-        self.launch_done = true;
+        if !self.launch_done && success {
+            self.launch_done = true;
+        }
 
-        if success {
+        if !success {
             let error = InstructionError::read();
             if error.0 != 0 {
                 return Err(error);
@@ -530,7 +532,7 @@ impl VCpu {
             "pop r14",
             "pop r15",
             "pop rbp",
-            "mov rax, 1",
+            "mov rax, 0",
             "ret",
             const RAX_OFFSET,
             const RCX_OFFSET,