From d860c4a63ee453ab5455f37ca3c60a329ed0f25e Mon Sep 17 00:00:00 2001
From: Chuanxiao Dong <chuanxiao.dong@intel.com>
Date: Mon, 8 Jul 2024 15:59:04 +0800
Subject: [PATCH] dm: Add initial device model project

The device model is a user mode program which manages VM's life cycles
and handles various vmexits events. The initial version just calls exit()
syscall without doing anything else.

As this is a user mode program, not sure what is the preferred way to
put this project, just put it as a sub folder in coconut-svsm and in the
workspace. If in the workspace is not preferred, this can be changed in
the future.

Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
---
 Cargo.lock     |  7 +++++++
 Cargo.toml     |  2 ++
 Makefile       |  9 +++++++--
 dm/Cargo.toml  | 15 +++++++++++++++
 dm/build.rs    |  6 ++++++
 dm/dm.lds      | 21 +++++++++++++++++++++
 dm/src/main.rs | 25 +++++++++++++++++++++++++
 7 files changed, 83 insertions(+), 2 deletions(-)
 create mode 100644 dm/Cargo.toml
 create mode 100644 dm/build.rs
 create mode 100644 dm/dm.lds
 create mode 100644 dm/src/main.rs

diff --git a/Cargo.lock b/Cargo.lock
index 577ea5d15..451b15fa9 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -336,6 +336,13 @@ dependencies = [
  "subtle",
 ]
 
+[[package]]
+name = "dm"
+version = "0.1.0"
+dependencies = [
+ "syscall",
+]
+
 [[package]]
 name = "ecdsa"
 version = "0.16.9"
diff --git a/Cargo.toml b/Cargo.toml
index d73ea81b9..59dfac94b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,6 +16,8 @@ members = [
     "syscall",
     # init process
     "init",
+    # device model application
+    "dm",
 ]
 
 
diff --git a/Makefile b/Makefile
index efdb2500c..de55f8c9f 100644
--- a/Makefile
+++ b/Makefile
@@ -45,6 +45,7 @@ IGVMBIN = bin/igvmbld
 IGVMMEASURE = "target/x86_64-unknown-linux-gnu/${TARGET_PATH}/igvmmeasure"
 IGVMMEASUREBIN = bin/igvmmeasure
 INITELF = "target/x86_64-unknown-none/${TARGET_PATH}/init"
+DMELF = "target/x86_64-unknown-none/${TARGET_PATH}/dm"
 
 RUSTDOC_OUTPUT = target/x86_64-unknown-none/doc
 DOC_SITE = target/x86_64-unknown-none/site
@@ -134,7 +135,11 @@ bin/init: bin
 	cargo build --manifest-path init/Cargo.toml ${CARGO_ARGS} --bin init
 	objcopy -O elf64-x86-64 --strip-unneeded ${INITELF} $@
 
-user: bin/init
+bin/dm: bin
+	cargo build --manifest-path dm/Cargo.toml ${CARGO_ARGS} --bin dm
+	objcopy -O elf64-x86-64 --strip-unneeded ${DMELF} $@
+
+user: bin/init bin/dm
 
 ${FS_BIN}: bin
 ifneq ($(FS_FILE), none)
@@ -177,7 +182,7 @@ bin/svsm-test.bin: bin/stage1-test
 
 clippy:
 	cargo clippy --workspace --all-features --exclude svsm-fuzz --exclude igvmbuilder --exclude igvmmeasure -- -D warnings
-	cargo clippy --workspace --all-features --exclude svsm-fuzz --exclude svsm --exclude init --target=x86_64-unknown-linux-gnu -- -D warnings
+	cargo clippy --workspace --all-features --exclude svsm-fuzz --exclude svsm --exclude init --exclude dm --target=x86_64-unknown-linux-gnu -- -D warnings
 	RUSTFLAGS="--cfg fuzzing" cargo clippy --package svsm-fuzz --all-features --target=x86_64-unknown-linux-gnu -- -D warnings
 	cargo clippy --workspace --all-features --tests --target=x86_64-unknown-linux-gnu -- -D warnings
 
diff --git a/dm/Cargo.toml b/dm/Cargo.toml
new file mode 100644
index 000000000..0032aab13
--- /dev/null
+++ b/dm/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "dm"
+version = "0.1.0"
+edition = "2021"
+
+[[bin]]
+name = "dm"
+path = "src/main.rs"
+test = false
+
+[dependencies]
+syscall = { path = "../syscall" }
+
+[lints]
+workspace = true
diff --git a/dm/build.rs b/dm/build.rs
new file mode 100644
index 000000000..298fb377f
--- /dev/null
+++ b/dm/build.rs
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+fn main() {
+    println!("cargo:rustc-link-arg-bin=dm=-nostdlib");
+    println!("cargo:rustc-link-arg-bin=dm=-no-pie");
+    println!("cargo:rustc-link-arg-bin=dm=-Tdm/dm.lds");
+}
diff --git a/dm/dm.lds b/dm/dm.lds
new file mode 100644
index 000000000..3b154843b
--- /dev/null
+++ b/dm/dm.lds
@@ -0,0 +1,21 @@
+OUTPUT_ARCH(i386:x86-64)
+
+SECTIONS
+{
+	.text : {
+		*(.text)
+		*(.text.*)
+	}
+	. = ALIGN(4096);
+	.rodata : { *(.rodata) *(.rodata.*) }
+	. = ALIGN(4096);
+	.data : { *(.data) *(.data.*) }
+	. = ALIGN(4096);
+	.bss : {
+		*(.bss) *(.bss.*)
+		. = ALIGN(4096);
+	}
+	. = ALIGN(4096);
+}
+
+ENTRY(dm_start)
diff --git a/dm/src/main.rs b/dm/src/main.rs
new file mode 100644
index 000000000..f7ea0a532
--- /dev/null
+++ b/dm/src/main.rs
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+//
+// Copyright (c) 2024 Intel Corporation.
+//
+// Author: Chuanxiao Dong <chuanxiao.dong@intel.com>
+
+#![no_std]
+#![no_main]
+
+use core::panic::PanicInfo;
+use syscall::exit;
+
+fn dm_exit() -> ! {
+    exit(0);
+}
+
+#[no_mangle]
+pub extern "C" fn dm_start() -> ! {
+    dm_exit();
+}
+
+#[panic_handler]
+fn panic(_info: &PanicInfo<'_>) -> ! {
+    dm_exit();
+}