test: make it possible to run tests inside SVSM

To build and run a kernel that runs the tests use
```
QEMU=/path/to/qemu OVMF=/path/to/firmware/ make test-in-svsm
```

Signed-off-by: Tom Dohrmann <[email protected]>

Cargo.toml

@@ -24,7 +24,8 @@ gdbstub_arch = { version = "0.2.4", optional = true }
 log = { version = "0.4.17", features = ["max_level_info", "release_max_level_info"] }
 packit = { git = "https://github.com/coconut-svsm/packit", version = "0.1.0" }
 
-[build-dependencies]
+[target."x86_64-unknown-none".dev-dependencies]
+test = { version = "0.1.0", path = "test" }
 
 [features]
 default = ["enable-stacktrace"]

Makefile

@@ -2,23 +2,49 @@ FEATURES ?= "default"
 CARGO_ARGS = --features ${FEATURES}
 
 ifdef RELEASE
-TARGET_PATH="release"
+TARGET_PATH=release
 CARGO_ARGS += --release
 else
-TARGET_PATH="debug"
+TARGET_PATH=debug
 endif
 
 STAGE2_ELF = "target/x86_64-unknown-none/${TARGET_PATH}/stage2"
 KERNEL_ELF = "target/x86_64-unknown-none/${TARGET_PATH}/svsm"
+TEST_KERNEL_ELF = target/x86_64-unknown-none/${TARGET_PATH}/svsm-test
 FS_FILE ?= none
 
+C_BIT_POS ?= 51
+
 STAGE1_OBJS = stage1/stage1.o stage1/reset.o
 
 all: stage1/kernel.elf svsm.bin
 
 test:
 	cargo test --target=x86_64-unknown-linux-gnu
 
+test-in-svsm: stage1/test-kernel.elf svsm.bin
+ifndef QEMU
+	echo "Set QEMU environment variable to QEMU installation path" && exit 1
+endif
+ifndef OVMF
+	echo "Set OVMFenvironment variable to a folder containing OVMF_CODE.fd and OVMF_VARS.fd" && exit 1
+endif
+	$(QEMU)/qemu-system-x86_64 \
+		-enable-kvm \
+		-cpu EPYC-v4 \
+		-machine q35,confidential-guest-support=sev0,memory-backend=ram1,kvm-type=protected \
+		-object memory-backend-memfd-private,id=ram1,size=1G,share=true \
+		-object sev-snp-guest,id=sev0,cbitpos=$(C_BIT_POS),reduced-phys-bits=1,svsm=on \
+		-smp 8 \
+		-no-reboot \
+		-drive if=pflash,format=raw,unit=0,file=$(OVMF)/OVMF_CODE.fd,readonly=on \
+		-drive if=pflash,format=raw,unit=1,file=$(OVMF)/OVMF_VARS.fd,snapshot=on \
+		-drive if=pflash,format=raw,unit=2,file=./svsm.bin,readonly=on \
+		-nographic \
+		-monitor none \
+		-serial stdio \
+		-device isa-debug-exit,iobase=0xf4,iosize=0x04 || true
+
 utils/gen_meta: utils/gen_meta.c
 	cc -O3 -Wall -o $@ $<
 
@@ -36,6 +62,10 @@ stage1/kernel.elf:
 	cargo build ${CARGO_ARGS} --bin svsm
 	objcopy -O elf64-x86-64 --strip-unneeded ${KERNEL_ELF} $@
 
+stage1/test-kernel.elf:
+	LINK_TEST=1 cargo +nightly test --config 'target.x86_64-unknown-none.runner=["sh", "-c", "cp $$0 ${TEST_KERNEL_ELF}"]'
+	objcopy -O elf64-x86-64 --strip-unneeded ${TEST_KERNEL_ELF} stage1/kernel.elf
+
 stage1/svsm-fs.bin:
 ifneq ($(FS_FILE), none)
 	cp -f $(FS_FILE) stage1/svsm-fs.bin
@@ -57,4 +87,4 @@ clean:
 	cargo clean
 	rm -f stage1/stage2.bin svsm.bin stage1/meta.bin stage1/kernel.elf stage1/stage1 stage1/svsm-fs.bin ${STAGE1_OBJS} utils/gen_meta utils/print-meta
 
-.PHONY: stage1/stage2.bin stage1/kernel.elf svsm.bin clean stage1/svsm-fs.bin test
+.PHONY: stage1/stage2.bin stage1/kernel.elf stage1/test-kernel.elf svsm.bin clean stage1/svsm-fs.bin test test-in-svsm

build.rs

@@ -17,4 +17,14 @@ fn main() {
     println!("cargo:rustc-link-arg-bin=svsm=--no-relax");
     println!("cargo:rustc-link-arg-bin=svsm=-Tsvsm.lds");
     println!("cargo:rustc-link-arg-bin=svsm=-no-pie");
+
+    // Extra linker args for tests.
+    println!("cargo:rerun-if-env-changed=LINK_TEST");
+    if std::env::var("LINK_TEST").is_ok() {
+        println!("cargo:rustc-link-arg=-nostdlib");
+        println!("cargo:rustc-link-arg=--build-id=none");
+        println!("cargo:rustc-link-arg=--no-relax");
+        println!("cargo:rustc-link-arg=-Tsvsm.lds");
+        println!("cargo:rustc-link-arg=-no-pie");
+    }
 }

src/lib.rs

@@ -5,6 +5,16 @@
 // Author: Nicolai Stange <[email protected]>
 
 #![no_std]
+#![cfg_attr(all(test, target_os = "none"), no_main)]
+#![cfg_attr(all(test, target_os = "none"), feature(custom_test_frameworks))]
+#![cfg_attr(
+    all(test, target_os = "none"),
+    test_runner(crate::testing::svsm_test_runner)
+)]
+#![cfg_attr(
+    all(test, target_os = "none"),
+    reexport_test_harness_main = "test_main"
+)]
 
 pub mod acpi;
 pub mod address;
@@ -33,3 +43,15 @@ pub mod utils;
 
 #[test]
 fn test_nop() {}
+
+// When running tests inside the SVSM:
+// Build the kernel entrypoint.
+#[cfg(all(test, target_os = "none"))]
+#[path = "svsm.rs"]
+pub mod svsm_bin;
+// The kernel expects to access this crate as svsm, so reexport.
+#[cfg(all(test, target_os = "none"))]
+extern crate self as svsm;
+// Include a module containing the test runner.
+#[cfg(all(test, target_os = "none"))]
+pub mod testing;

src/svsm.rs

@@ -4,8 +4,8 @@
 //
 // Author: Joerg Roedel <[email protected]>
 
-#![no_std]
-#![no_main]
+#![cfg_attr(not(test), no_std)]
+#![cfg_attr(not(test), no_main)]
 
 extern crate alloc;
 
@@ -470,6 +470,9 @@ pub extern "C" fn svsm_main() {
         panic!("Failed to launch FW: {:#?}", e);
     }
 
+    #[cfg(test)]
+    crate::test_main();
+
     request_loop();
 
     panic!("Road ends here!");

src/testing.rs

@@ -0,0 +1,33 @@
+use log::info;
+use test::ShouldPanic;
+
+use crate::sev::msr_protocol::request_termination_msr;
+
+pub fn svsm_test_runner(test_cases: &[&test::TestDescAndFn]) {
+    info!("running {} tests", test_cases.len());
+    for mut test_case in test_cases.iter().copied().copied() {
+        if test_case.desc.should_panic == ShouldPanic::Yes {
+            test_case.desc.ignore = true;
+            test_case
+                .desc
+                .ignore_message
+                .get_or_insert("#[should_panic] not supported");
+        }
+
+        if test_case.desc.ignore {
+            if let Some(message) = test_case.desc.ignore_message {
+                info!("test {} ... ignored, {message}", test_case.desc.name.0);
+            } else {
+                info!("test {} ... ignored", test_case.desc.name.0);
+            }
+            continue;
+        }
+
+        info!("test {} ...", test_case.desc.name.0);
+        (test_case.testfn.0)();
+    }
+
+    info!("All tests passed!");
+
+    request_termination_msr();
+}