From 52f129208bcff887442e12e2559faa7a350aed2c Mon Sep 17 00:00:00 2001
From: Masato Imai <mii@sfc.wide.ad.jp>
Date: Wed, 6 Aug 2025 08:33:07 +0000
Subject: [PATCH] EPT EntryBase

---
 nel_os_kernel/src/vmm/x86_64/intel/ept.rs | 69 +++++++++++++++++++++++
 nel_os_kernel/src/vmm/x86_64/intel/mod.rs |  1 +
 2 files changed, 70 insertions(+)
 create mode 100644 nel_os_kernel/src/vmm/x86_64/intel/ept.rs

diff --git a/nel_os_kernel/src/vmm/x86_64/intel/ept.rs b/nel_os_kernel/src/vmm/x86_64/intel/ept.rs
new file mode 100644
index 0000000..91c45de
--- /dev/null
+++ b/nel_os_kernel/src/vmm/x86_64/intel/ept.rs
@@ -0,0 +1,69 @@
+use modular_bitfield::{
+    bitfield,
+    prelude::{B3, B53},
+    Specifier,
+};
+use x86_64::{
+    structures::paging::{FrameAllocator, PhysFrame, Size4KiB},
+    PhysAddr,
+};
+
+pub struct EPT {
+    pub root_table: PhysFrame,
+}
+
+impl EPT {
+    pub fn new(allocator: &mut impl FrameAllocator<Size4KiB>) -> Result<Self, &'static str> {
+        let root_table_frame = allocator
+            .allocate_frame()
+            .ok_or("Failed to allocate EPT root table frame")?;
+
+        Ok(Self {
+            root_table: root_table_frame,
+        })
+    }
+
+    fn init_table(frame: &PhysFrame) {}
+}
+
+#[bitfield]
+#[repr(u64)]
+#[derive(Debug, Clone, Copy)]
+pub struct EntryBase {
+    pub read: bool,
+    pub write: bool,
+    pub exec_super: bool,
+    pub typ: B3,
+    pub ignore_pat: bool,
+    pub map_memory: bool,
+    pub accessed: bool,
+    pub dirty: bool,
+    pub exec_user: bool,
+    pub phys: B53,
+}
+
+impl EntryBase {
+    pub fn is_present(&self) -> bool {
+        self.read() || self.write() || self.exec_super()
+    }
+
+    pub fn address(&self) -> PhysAddr {
+        PhysAddr::new(self.phys() << 12)
+    }
+}
+
+impl Default for EntryBase {
+    fn default() -> Self {
+        Self::new()
+            .with_read(true)
+            .with_write(true)
+            .with_exec_super(true)
+            .with_typ(0)
+            .with_ignore_pat(false)
+            .with_map_memory(false)
+            .with_accessed(false)
+            .with_dirty(false)
+            .with_exec_user(true)
+            .with_phys(0)
+    }
+}
diff --git a/nel_os_kernel/src/vmm/x86_64/intel/mod.rs b/nel_os_kernel/src/vmm/x86_64/intel/mod.rs
index e7ddf7e..83614b2 100644
--- a/nel_os_kernel/src/vmm/x86_64/intel/mod.rs
+++ b/nel_os_kernel/src/vmm/x86_64/intel/mod.rs
@@ -1,5 +1,6 @@
 pub mod asm;
 mod controls;
+mod ept;
 mod register;
 pub mod vcpu;
 mod vmcs;