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.

Co-developed-by: Vijay Dhanraj <[email protected]>
Signed-off-by: Chuanxiao Dong <[email protected]>

.github/workflows/rust.yml

@@ -62,7 +62,7 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: clippy
-          args: --workspace --all-features --exclude svsm --exclude svsm-fuzz --exclude init --target=x86_64-unknown-linux-gnu -- -D warnings
+          args: --workspace --all-features --exclude svsm --exclude svsm-fuzz --exclude init --exclude dm --target=x86_64-unknown-linux-gnu -- -D warnings
 
       - name: Clippy on svsm-fuzz
         uses: actions-rs/cargo@v1

Cargo.toml

@@ -16,6 +16,8 @@ members = [
     "syscall",
     # init process
     "init",
+    # device model application
+    "dm",
 ]
 
 

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
@@ -140,7 +141,11 @@ 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)
@@ -183,7 +188,7 @@ 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
 

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

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");
+}

dm/dm.lds

@@ -0,0 +1,37 @@
+/* Temporary WA until p_vaddr alignment issue is fixed in our ELF parser */
+
+OUTPUT_ARCH(i386:x86-64)
+
+PHDRS
+{
+	text PT_LOAD FLAGS(5);		/* Read + Execute */
+	rodata PT_LOAD FLAGS(4);	/* Read-only */
+	data PT_LOAD FLAGS(6);		/* Read + Write */
+	bss PT_LOAD FLAGS(6);		/* Read + Write */
+}
+
+SECTIONS
+{
+	.text : {
+		*(.text)
+		*(.text.*)
+	} :text
+	. = ALIGN(4096);
+	.rodata : {
+		*(.rodata)
+		*(.rodata.*)
+	} :rodata
+	. = ALIGN(4096);
+	.data : {
+		*(.data)
+		*(.data.*)
+	} :data
+	. = ALIGN(4096);
+	.bss : {
+		*(.bss) *(.bss.*)
+		. = ALIGN(4096);
+	} :bss
+	. = ALIGN(4096);
+}
+
+ENTRY(dm_start)

dm/src/main.rs

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+//
+// Copyright (c) 2024 Intel Corporation.
+//
+// Author: Chuanxiao Dong <[email protected]>
+
+#![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();
+}