benchmark: Add riscv64 benchmark tests

As clippy command in our CI mandates: `cargo clippy --workspace --bins
--examples --benches --all-features --all-targets -- -D warnings -D
clippy::undocumented_unsafe_blocks`, add benchmarck test to appease
clippy.

Signed-off-by: Ruoqing He <[email protected]>

Author: RuoqingHe

benches/main.rs

@@ -21,6 +21,11 @@ mod aarch64;
 #[cfg(target_arch = "aarch64")]
 use aarch64::*;
 
+#[cfg(target_arch = "riscv64")]
+mod riscv64;
+#[cfg(target_arch = "riscv64")]
+use riscv64::*;
+
 criterion_group! {
     name = benches;
     config = Criterion::default().sample_size(500);

benches/riscv64/mod.rs

@@ -0,0 +1,50 @@
+// Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE-BSD-3-Clause file.
+//
+// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
+extern crate criterion;
+extern crate linux_loader;
+extern crate vm_memory;
+
+use linux_loader::configurator::fdt::FdtBootConfigurator;
+use linux_loader::configurator::{BootConfigurator, BootParams};
+use vm_memory::{ByteValued, GuestAddress, GuestMemoryMmap};
+
+use criterion::{black_box, Criterion};
+
+const MEM_SIZE: usize = 0x100_0000;
+const FDT_MAX_SIZE: usize = 0x20;
+
+fn create_guest_memory() -> GuestMemoryMmap {
+    GuestMemoryMmap::from_ranges(&[(GuestAddress(0x0), MEM_SIZE)]).unwrap()
+}
+
+#[derive(Clone, Copy, Default)]
+#[allow(dead_code)]
+pub struct FdtPlaceholder([u8; FDT_MAX_SIZE]);
+
+// SAFETY: The layout of the structure is fixed and can be initialized by
+// reading its content from byte array.
+unsafe impl ByteValued for FdtPlaceholder {}
+
+fn build_fdt_boot_params() -> BootParams {
+    let fdt = FdtPlaceholder([0u8; FDT_MAX_SIZE]);
+    let fdt_addr = GuestAddress((MEM_SIZE - FDT_MAX_SIZE - 1) as u64);
+    BootParams::new::<FdtPlaceholder>(&fdt, fdt_addr)
+}
+
+pub fn criterion_benchmark(c: &mut Criterion) {
+    let guest_mem = create_guest_memory();
+    let fdt_boot_params = build_fdt_boot_params();
+    c.bench_function("configure_fdt", |b| {
+        b.iter(|| {
+            black_box(FdtBootConfigurator::write_bootparams::<GuestMemoryMmap>(
+                &fdt_boot_params,
+                &guest_mem,
+            ))
+            .unwrap();
+        })
+    });
+}