chore(utils): add usize_to_u64 to utils

Usize to u64 is safe as Firecracker only supports 64bit
platforms where usize == u64.

Signed-off-by: Egor Lazarchuk <[email protected]>

Author: ShadowCurse

src/utils/src/lib.rs

@@ -41,6 +41,15 @@ pub const fn u64_to_usize(num: u64) -> usize {
     num as usize
 }
 
+/// Safely converts a usize value to a u64 value.
+/// This bypasses the Clippy lint check because we only support 64-bit platforms.
+#[cfg(target_pointer_width = "64")]
+#[inline]
+#[allow(clippy::cast_possible_truncation)]
+pub const fn usize_to_u64(num: usize) -> u64 {
+    num as u64
+}
+
 /// Converts a usize into a wrapping u32.
 #[inline]
 pub const fn wrap_usize_to_u32(num: usize) -> Wrapping<u32> {