Add definition for flags in IGVM_VHS_MEMORY_MAP_ENTRY (#8)

Add meaning for the flags field in the IGVM_VHS_MEMORY_MAP_ENTRY
structure. #9

igvm_defs/src/lib.rs

@@ -1017,6 +1017,17 @@ impl Default for MemoryMapEntryType {
     }
 }
 
+/// Flags associated with a memory map entry.
+#[bitfield(u16)]
+#[derive(AsBytes, FromBytes, FromZeroes, PartialEq, Eq)]
+pub struct MemoryMapEntryFlags {
+    /// Memory is in the shared state, and an explicit call must be made to
+    /// change it to the private state before it can be accepted and used.
+    pub is_shared: bool,
+    #[bits(15)]
+    pub reserved: u16,
+}
+
 /// The structure deposited by the loader for memory map entries for
 /// [`IgvmVariableHeaderType::IGVM_VHT_MEMORY_MAP`] that describe memory
 /// available to the guest.
@@ -1033,7 +1044,7 @@ pub struct IGVM_VHS_MEMORY_MAP_ENTRY {
     /// The type of memory this entry represents.
     pub entry_type: MemoryMapEntryType,
     /// Flags about this memory entry.
-    pub flags: u16,
+    pub flags: MemoryMapEntryFlags,
     /// Reserved.
     pub reserved: u32,
 }