arch: preserve error chain for smbios

On-behalf-of: SAP philipp.schuster@sap.com
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>

arch/src/lib.rs

@@ -39,7 +39,7 @@ pub enum Error {
     #[error("The hvm_start_info structure extends past the end of guest memory")]
     StartInfoPastRamEnd,
     #[error("Error writing hvm_start_info to guest memory")]
-    StartInfoSetup,
+    StartInfoSetup(#[source] vm_memory::GuestMemoryError),
     #[error("Failed to compute initramfs address")]
     InitramfsAddress,
     #[error("Error writing module entry to guest memory")]

arch/src/x86_64/mod.rs

@@ -1282,7 +1282,7 @@ fn configure_pvh(
     // Write the start_info struct to guest memory.
     guest_mem
         .write_obj(start_info, start_info_addr)
-        .map_err(|_| super::Error::StartInfoSetup)?;
+        .map_err(super::Error::StartInfoSetup)?;
 
     Ok(())
 }

arch/src/x86_64/smbios.rs

@@ -28,10 +28,10 @@ pub enum Error {
     Clear,
     /// Failure to write SMBIOS entrypoint structure
     #[error("Failure to write SMBIOS entrypoint structure")]
-    WriteSmbiosEp,
+    WriteSmbiosEp(#[source] vm_memory::GuestMemoryError),
     /// Failure to write additional data to memory
     #[error("Failure to write additional data to memory")]
-    WriteData,
+    WriteData(#[source] vm_memory::GuestMemoryError),
     /// Failure to parse uuid, uuid format may be error
     #[error("Failure to parse uuid: {1}")]
     ParseUuid(#[source] uuid::Error, String),
@@ -207,7 +207,7 @@ fn write_and_incr<T: ByteValued>(
     val: T,
     mut curptr: GuestAddress,
 ) -> Result<GuestAddress> {
-    mem.write_obj(val, curptr).map_err(|_| Error::WriteData)?;
+    mem.write_obj(val, curptr).map_err(Error::WriteData)?;
     curptr = curptr
         .checked_add(mem::size_of::<T>() as u64)
         .ok_or(Error::NotEnoughMemory)?;
@@ -449,7 +449,7 @@ pub fn setup_smbios(mem: &GuestMemoryMmap, smbios: Option<&SmbiosConfig>) -> Res
         };
         smbios_ep.checksum = compute_checksum(&smbios_ep);
         mem.write_obj(smbios_ep, GuestAddress(SMBIOS_START))
-            .map_err(|_| Error::WriteSmbiosEp)?;
+            .map_err(Error::WriteSmbiosEp)?;
     }
 
     Ok(curptr.unchecked_offset_from(physptr) + std::mem::size_of::<Smbios30Entrypoint>() as u64)
@@ -704,6 +704,6 @@ mod unit_tests {
         .unwrap();
 
         let err = setup_smbios(&mem, None).unwrap_err();
-        assert!(matches!(err, Error::WriteData));
+        assert!(matches!(err, Error::WriteData(_)));
     }
 }