feat(tdx): add struct and const definitions for TDVF

Signed-off-by: Changyuan Lyu <changyuanl@google.com>

Author: Lencerf

alioth/src/firmware/ovmf/ovmf_x86_64/ovmf_x86_64.rs

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 pub mod sev;
+pub mod tdx;
 
 use zerocopy::FromBytes;
 

alioth/src/firmware/ovmf/ovmf_x86_64/tdx.rs

@@ -0,0 +1,62 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use zerocopy::{FromBytes, Immutable, IntoBytes, KnownLayout};
+
+use crate::firmware::ovmf::x86_64::GUID_SIZE;
+use crate::{bitflags, consts};
+
+pub const GUID_TDX_METADATA_OFFSET: [u8; GUID_SIZE] = [
+    0x35, 0x65, 0x7a, 0xe4, 0x4a, 0x98, 0x98, 0x47, 0x86, 0x5e, 0x46, 0x85, 0xa7, 0xbf, 0x8e, 0xc2,
+];
+pub const TDVF_SIGNATURE: u32 = u32::from_le_bytes(*b"TDVF");
+pub const TDVF_VERSION: u32 = 1;
+
+#[repr(C)]
+#[derive(Debug, Clone, Default, KnownLayout, Immutable, FromBytes, IntoBytes)]
+pub struct TdvfMetadata {
+    pub signature: u32,
+    pub length: u32,
+    pub version: u32,
+    pub number_of_entries: u32,
+}
+
+consts! {
+    #[derive(Default, KnownLayout, Immutable, FromBytes, IntoBytes)]
+    pub struct TdvfSectionType(u32) {
+        BFV = 0;
+        CFV = 1;
+        TD_HOB = 2;
+        TEMP_MEM = 3;
+    }
+}
+
+bitflags! {
+    #[derive(Default, KnownLayout, Immutable, FromBytes, IntoBytes)]
+    pub struct TdvfSectionAttribute(u32) {
+        MR_EXTEND = 1 << 0;
+        PAGE_AUG = 1 << 1;
+    }
+}
+
+#[repr(C)]
+#[derive(Debug, Clone, Default, KnownLayout, Immutable, FromBytes, IntoBytes)]
+pub struct TdxMetadataSection {
+    pub data_offset: u32,
+    pub raw_data_size: u32,
+    pub memory_address: u64,
+    pub memory_data_size: u64,
+    pub r#type: TdvfSectionType,
+    pub attributes: TdvfSectionAttribute,
+}