arm: use BootConfigurator to write fdt in memory

src/configurator/aarch64/fdt.rs

@@ -0,0 +1,72 @@
+// Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
+
+//! Traits and structs for loading the device tree.
+
+use vm_memory::{ByteValued, Bytes, GuestAddress, GuestMemory};
+
+use std::error::Error as StdError;
+use std::fmt;
+
+use super::super::{BootConfigurator, Error as BootConfiguratorError, Result};
+
+/// Errors specific to the device tree boot protocol configuration.
+#[derive(Debug, PartialEq)]
+pub enum Error {
+    /// Error writing FDT in memory.
+    WriteFDTToMemory,
+}
+
+impl StdError for Error {
+    fn description(&self) -> &str {
+        use Error::*;
+        match self {
+            WriteFDTToMemory => "Error writing FDT in guest memory.",
+        }
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "Device Tree Boot Configurator Error: {}",
+            StdError::description(self)
+        )
+    }
+}
+
+impl From<Error> for BootConfiguratorError {
+    fn from(err: Error) -> Self {
+        BootConfiguratorError::Fdt(err)
+    }
+}
+
+/// Boot configurator for device tree.
+pub struct FdtBootConfigurator {}
+
+impl BootConfigurator for FdtBootConfigurator {
+    /// Writes the boot parameters (configured elsewhere) into guest memory.
+    ///
+    /// # Arguments
+    ///
+    /// * `fdt` - flattened device tree.
+    /// * `sections` - unused.
+    /// * `guest_memory` - guest's physical memory.
+    fn write_bootparams<T, S, M>(
+        fdt: (T, GuestAddress),
+        _sections: Option<(Vec<S>, GuestAddress)>,
+        guest_memory: &M,
+    ) -> Result<()>
+    where
+        T: ByteValued,
+        S: ByteValued,
+        M: GuestMemory,
+    {
+        // The VMM has filled an FDT and passed it as a `ByteValued` object.
+        guest_memory
+            .write_obj(fdt.0, fdt.1)
+            .map_err(|_| Error::WriteFDTToMemory.into())
+    }
+}

src/configurator/aarch64/mod.rs

@@ -6,24 +6,4 @@
 
 #![cfg(target_arch = "aarch64")]
 
-use std::error::Error as StdError;
-use std::fmt;
-
-/// Placeholder error type.
-#[derive(Debug, PartialEq)]
-pub enum Error {
-    /// Placeholder error value.
-    Placeholder,
-}
-
-impl StdError for Error {
-    fn description(&self) -> &str {
-        unimplemented!()
-    }
-}
-
-impl fmt::Display for Error {
-    fn fmt(&self, _f: &mut fmt::Formatter) -> fmt::Result {
-        unimplemented!()
-    }
-}
+pub mod fdt;

src/configurator/mod.rs

@@ -29,7 +29,7 @@ pub use x86_64::*;
 #[cfg(target_arch = "aarch64")]
 mod aarch64;
 #[cfg(target_arch = "aarch64")]
-pub use aarch64::Error as ArmError;
+pub use aarch64::*;
 
 /// Errors specific to boot protocol configuration.
 #[derive(Debug, PartialEq)]
@@ -42,7 +42,7 @@ pub enum Error {
     Pvh(pvh::Error),
     /// Errors specific to device tree boot configuration.
     #[cfg(target_arch = "aarch64")]
-    Arm(ArmError),
+    Fdt(fdt::Error),
 }
 
 impl StdError for Error {
@@ -54,7 +54,7 @@ impl StdError for Error {
             #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Pvh(ref e) => e.description(),
             #[cfg(target_arch = "aarch64")]
-            Arm(ref e) => e.description(),
+            Fdt(ref e) => e.description(),
         }
     }
 }