selftests/liveupdate: add end to end test infrastructure and scripts

Add the end to end testing infrastructure required to verify the
liveupdate feature. This includes a custom init process, a test
orchestration script, and a batch runner.

The framework consists of:

init.c:
A lightweight init process that manages the kexec lifecycle.
It mounts necessary filesystems, determines the current execution
stage (1 or 2) via the kernel command line, and handles the
kexec_file_load() sequence to transition between kernels.

vmtest.sh:
The primary KTAP-compliant test driver. It handles:
- Kernel configuration merging and building.
- Cross-compilation detection for x86_64 and arm64.
- Generation of the initrd containing the test binary and init.
- QEMU execution with automatic accelerator detection (KVM, HVF,
 or TCG).

run-vmtests.sh:
A wrapper that runs vmtest.sh for each LUO test across supported
architectures, providing a summary of pass/fail/skip results.

Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Co-developed-by: Jordan Richards <jordanrichards@google.com>
Signed-off-by: Jordan Richards <jordanrichards@google.com>
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Pratyush Yadav <pratyush@kernel.org>
Link: https://patch.msgid.link/20260626-luo-vmtest-v0-v4-1-e7d3111cd5b3@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

tools/testing/selftests/liveupdate/.gitignore

@@ -6,4 +6,5 @@
 !*.sh
 !.gitignore
 !config
+!config.*
 !Makefile

tools/testing/selftests/liveupdate/config

@@ -1,4 +1,5 @@
 CONFIG_BLK_DEV_INITRD=y
+CONFIG_DEVTMPFS=y
 CONFIG_KEXEC_FILE=y
 CONFIG_KEXEC_HANDOVER=y
 CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT=y

tools/testing/selftests/liveupdate/config.aarch64

@@ -0,0 +1,2 @@
+CONFIG_SERIAL_AMBA_PL011=y
+CONFIG_SERIAL_AMBA_PL011_CONSOLE=y

tools/testing/selftests/liveupdate/config.x86_64

@@ -0,0 +1,2 @@
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y

tools/testing/selftests/liveupdate/init.c

@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (c) 2025, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@soleen.com>
+ */
+#include <fcntl.h>
+#include <linux/kexec.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/reboot.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#define COMMAND_LINE_SIZE 2048
+#define KERNEL_IMAGE "/kernel"
+#define INITRD_IMAGE "/initrd.img"
+#define TEST_BINARY "/test_binary"
+
+static int mount_filesystems(void)
+{
+	if (mount("devtmpfs", "/dev", "devtmpfs", 0, NULL) < 0) {
+		fprintf(stderr, "INIT: Warning: Failed to mount devtmpfs\n");
+		return -1;
+	}
+
+	if (mount("debugfs", "/debugfs", "debugfs", 0, NULL) < 0) {
+		fprintf(stderr, "INIT: Failed to mount debugfs\n");
+		return -1;
+	}
+
+	if (mount("proc", "/proc", "proc", 0, NULL) < 0) {
+		fprintf(stderr, "INIT: Failed to mount proc\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+static long kexec_file_load(int kernel_fd, int initrd_fd,
+			    unsigned long cmdline_len, const char *cmdline,
+			    unsigned long flags)
+{
+	return syscall(__NR_kexec_file_load, kernel_fd, initrd_fd, cmdline_len,
+		       cmdline, flags);
+}
+
+static int kexec_load(void)
+{
+	char cmdline[COMMAND_LINE_SIZE];
+	int kernel_fd, initrd_fd, err;
+	ssize_t len;
+	int fd;
+
+	fd = open("/proc/cmdline", O_RDONLY);
+	if (fd < 0) {
+		fprintf(stderr, "INIT: Failed to read /proc/cmdline\n");
+
+		return -1;
+	}
+
+	len = read(fd, cmdline, sizeof(cmdline) - 1);
+	close(fd);
+	if (len < 0)
+		return -1;
+
+	cmdline[len] = 0;
+	if (len > 0 && cmdline[len - 1] == '\n')
+		cmdline[len - 1] = 0;
+
+	strncat(cmdline, " luo_stage=2", sizeof(cmdline) - strlen(cmdline) - 1);
+
+	kernel_fd = open(KERNEL_IMAGE, O_RDONLY);
+	if (kernel_fd < 0) {
+		fprintf(stderr, "INIT: Failed to open kernel image\n");
+		return -1;
+	}
+
+	initrd_fd = open(INITRD_IMAGE, O_RDONLY);
+	if (initrd_fd < 0) {
+		fprintf(stderr, "INIT: Failed to open initrd image\n");
+		close(kernel_fd);
+		return -1;
+	}
+
+	err = kexec_file_load(kernel_fd, initrd_fd, strlen(cmdline) + 1,
+			      cmdline, 0);
+
+	close(initrd_fd);
+	close(kernel_fd);
+
+	return err;
+}
+
+static int run_test(int stage)
+{
+	char stage_arg[32];
+	int status;
+	pid_t pid;
+
+	snprintf(stage_arg, sizeof(stage_arg), "%d", stage);
+
+	pid = fork();
+	if (pid < 0)
+		return -1;
+
+	if (!pid) {
+		char *const argv[] = {TEST_BINARY, "-s", stage_arg, NULL};
+
+		execve(TEST_BINARY, argv, NULL);
+		fprintf(stderr, "INIT: execve failed\n");
+		_exit(1);
+	}
+
+	waitpid(pid, &status, 0);
+
+	return (WIFEXITED(status) && WEXITSTATUS(status) == 0) ? 0 : -1;
+}
+
+static int get_current_stage(void)
+{
+	char cmdline[COMMAND_LINE_SIZE];
+	ssize_t len;
+	int fd;
+
+	fd = open("/proc/cmdline", O_RDONLY);
+	if (fd < 0)
+		return -1;
+
+	len = read(fd, cmdline, sizeof(cmdline) - 1);
+	close(fd);
+
+	if (len < 0)
+		return -1;
+
+	cmdline[len] = 0;
+
+	return strstr(cmdline, "luo_stage=2") ? 2 : 1;
+}
+
+int main(int argc, char *argv[])
+{
+	int current_stage;
+	int err;
+
+	if (mount_filesystems())
+		goto err_reboot;
+
+	current_stage = get_current_stage();
+	if (current_stage < 0) {
+		fprintf(stderr, "INIT: Failed to read cmdline");
+		goto err_reboot;
+	}
+
+	printf("INIT: Starting Stage %d\n", current_stage);
+
+	if (current_stage == 1 && kexec_load()) {
+		fprintf(stderr, "INIT: Failed to load kexec kernel\n");
+		goto err_reboot;
+	}
+
+	if (run_test(current_stage)) {
+		fprintf(stderr, "INIT: Test binary returned failure\n");
+		goto err_reboot;
+	}
+
+	printf("INIT: Stage %d completed successfully.\n", current_stage);
+	reboot(current_stage == 1 ? RB_KEXEC : RB_AUTOBOOT);
+
+	return 0;
+
+err_reboot:
+	reboot(RB_AUTOBOOT);
+
+	return -1;
+}

tools/testing/selftests/liveupdate/luo_test_utils.c

@@ -21,6 +21,7 @@
 #include <sys/stat.h>
 #include <errno.h>
 #include <stdarg.h>
+#include <linux/unistd.h>
 
 #include "luo_test_utils.h"
 
@@ -81,7 +82,7 @@ int luo_retrieve_session(int luo_fd, const char *name)
 int create_and_preserve_memfd(int session_fd, int token, const char *data)
 {
 	struct liveupdate_session_preserve_fd arg = { .size = sizeof(arg) };
-	long page_size = sysconf(_SC_PAGE_SIZE);
+	long page_size = getpagesize();
 	void *map = MAP_FAILED;
 	int mfd = -1, ret = -1;
 
@@ -117,7 +118,7 @@ int restore_and_verify_memfd(int session_fd, int token,
 			     const char *expected_data)
 {
 	struct liveupdate_session_retrieve_fd arg = { .size = sizeof(arg) };
-	long page_size = sysconf(_SC_PAGE_SIZE);
+	long page_size = getpagesize();
 	void *map = MAP_FAILED;
 	int mfd = -1, ret = -1;
 
@@ -228,16 +229,11 @@ void daemonize_and_wait(void)
 
 static int parse_stage_args(int argc, char *argv[])
 {
-	static struct option long_options[] = {
-		{"stage", required_argument, 0, 's'},
-		{0, 0, 0, 0}
-	};
-	int option_index = 0;
 	int stage = 1;
 	int opt;
 
 	optind = 1;
-	while ((opt = getopt_long(argc, argv, "s:", long_options, &option_index)) != -1) {
+	while ((opt = getopt(argc, argv, "s:")) != -1) {
 		switch (opt) {
 		case 's':
 			stage = atoi(optarg);
@@ -248,6 +244,7 @@ static int parse_stage_args(int argc, char *argv[])
 			fail_exit("Unknown argument");
 		}
 	}
+
 	return stage;
 }
 
@@ -275,7 +272,7 @@ int luo_test(int argc, char *argv[],
 		fail_exit("Failed to check for state session");
 
 	if (target_stage != detected_stage) {
-		ksft_exit_fail_msg("Stage mismatch Requested --stage %d, but system is in stage %d.\n"
+		ksft_exit_fail_msg("Stage mismatch Requested stage %d, but system is in stage %d.\n"
 				   "(State session %s: %s)\n",
 				   target_stage, detected_stage, state_session_name,
 				   (detected_stage == 2) ? "EXISTS" : "MISSING");

tools/testing/selftests/liveupdate/run-vmtests.sh

@@ -0,0 +1,97 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+SCRIPT_DIR=$(dirname "$(realpath "$0")")
+TEST_RUNNER="$SCRIPT_DIR/vmtest.sh"
+
+TARGETS=("x86_64" "aarch64")
+
+GREEN='\033[0;32m'
+RED='\033[0;31m'
+YELLOW='\033[1;33m'
+NC='\033[0m'
+
+passed=0
+failed=0
+skipped=0
+
+TEST_NAMES=(
+	"luo_kexec_simple"
+	"luo_multi_session"
+	"luo_stress_files"
+	"luo_stress_sessions"
+)
+
+function usage() {
+	cat <<EOF
+$0 [-k] [-o output_dir] [-h]
+Options:
+	-k)	keep logs
+	-o)	specify output directory
+	-h)	display this help
+EOF
+}
+
+function pass() {
+	echo -e "${GREEN}PASS${NC}"
+	((passed++))
+}
+
+function skip() {
+	echo -e "${YELLOW}SKIP${NC}"
+	((skipped++))
+}
+
+function fail() {
+	echo -e "${RED}FAIL${NC}"
+	((failed++))
+}
+
+function main() {
+	while getopts 'hko:' opt; do
+		case $opt in
+		k) keep_logs=1 ;;
+		o) output_dir=$OPTARG ;;
+		h) usage; exit 0 ;;
+		*) echo Unknown argument "$opt"
+		   usage; exit 1 ;;
+		esac
+	done
+
+	if [ -n "$keep_logs" ]; then
+		if [ -z "$output_dir" ]; then
+			output_dir="$SCRIPT_DIR/results_$(date +%Y%m%d_%H%M%S)"
+		fi;
+		mkdir -p "$output_dir"
+	else
+		output_dir=$(mktemp -d /tmp/luo.XXXXXXXX)
+		trap 'rm -fr "$output_dir"' EXIT
+	fi
+
+	for arch in "${TARGETS[@]}"; do
+		for test_name in "${TEST_NAMES[@]}"; do
+			log="$output_dir/${arch}_${test_name}.log"
+
+			printf "  -> %-8s %-24s ... " "$arch" "$test_name"
+
+			"$TEST_RUNNER" -t "$arch" -T "$test_name" &> "$log"
+			exit_code=$?
+
+			case $exit_code in
+			0) pass;;
+			4) skip;;
+			*) fail;;
+			esac
+		done
+		echo ""
+	done
+
+	echo "SUMMARY: PASS=$passed SKIP=$skipped FAIL=$failed"
+	if [ -n "$keep_logs" ]; then
+		echo "Logs: $output_dir"
+	fi
+
+	exit $((failed != 0))
+}
+
+main "$@"

tools/testing/selftests/liveupdate/vmtest.sh

@@ -0,0 +1,263 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+set -ue
+
+CROSS_COMPILE="${CROSS_COMPILE:-""}"
+
+test_dir=$(realpath "$(dirname "$0")")
+kernel_dir=$(realpath "$test_dir/../../../..")
+
+workspace_dir=""
+headers_dir=""
+initrd=""
+KEEP_WORKSPACE=0
+
+source "$test_dir/../kselftest/ktap_helpers.sh"
+
+function get_arch_conf() {
+	local arch=$1
+	if [[ "$arch" == "arm64" ]]; then
+		QEMU_CMD="qemu-system-aarch64 -M virt -cpu max"
+		KERNEL_IMAGE="Image"
+		KERNEL_CMDLINE="console=ttyAMA0"
+	elif [[ "$arch" == "x86" ]]; then
+		QEMU_CMD="qemu-system-x86_64"
+		KERNEL_IMAGE="bzImage"
+		KERNEL_CMDLINE="console=ttyS0"
+	else
+		echo "Unsupported architecture: $arch"
+		exit 1
+	fi
+}
+
+function usage() {
+	cat <<EOF
+$0 [-d build_dir] [-j jobs] [-t target_arch] [-T test_name] [-w workspace_dir] [-k] [-h]
+Options:
+	-d)	path to the kernel build directory (default: .luo_test_build.<arch>)
+	-j)	number of jobs for compilation
+	-t)	run test for target_arch (aarch64, x86_64)
+	-T)	test name to run (default: luo_kexec_simple)
+	-w)	custom workspace directory (default: creates temp dir)
+	-k)	keep workspace directory after successful test
+	-h)	display this help
+EOF
+}
+
+function cleanup() {
+	if [ "$KEEP_WORKSPACE" -eq 1 ]; then
+		echo "# Workspace preserved at: $workspace_dir"
+	else
+		rm -fr "$workspace_dir"
+	fi
+
+	ktap_finished
+}
+
+function skip() {
+	local msg=${1:-""}
+	ktap_test_skip "$msg"
+	exit "$KSFT_SKIP"
+}
+
+function fail() {
+	local msg=${1:-""}
+	ktap_test_fail "$msg"
+	exit "$KSFT_FAIL"
+}
+
+function detect_cross_compile() {
+	local target=$1
+	local host=$(uname -m)
+
+	[[ "$host" == "arm64" ]] && host="aarch64"
+	[[ "$target" == "arm64" ]] && target="aarch64"
+
+	if [[ "$host" == "$target" ]]; then
+		CROSS_COMPILE=""
+		return
+	fi
+
+	if [[ -n "$CROSS_COMPILE" ]]; then
+		return
+	fi
+
+	local candidate=""
+	case "$target" in
+		aarch64) candidate="aarch64-linux-gnu-" ;;
+		x86_64)  candidate="x86_64-linux-gnu-" ;;
+		*)       skip "Auto-detection for target '$target' not supported. Please set CROSS_COMPILE manually." ;;
+	esac
+
+	if command -v "${candidate}gcc" &> /dev/null; then
+		CROSS_COMPILE="$candidate"
+	else
+		skip "Compiler '${candidate}gcc' not found. Please install it (e.g., 'apt install gcc-aarch64-linux-gnu') or set CROSS_COMPILE."
+	fi
+}
+
+function build_kernel() {
+	local build_dir=$1
+	local make_cmd=$2
+	local kimage=$3
+	local target_arch=$4
+
+	local luo_config="$build_dir/luo.config"
+	local kconfig="$build_dir/.config"
+	local common_conf="$test_dir/config"
+	local arch_conf="$test_dir/config.$target_arch"
+
+	echo "# Building kernel in: $build_dir"
+
+	cat "$arch_conf" "$common_conf" | tee "$kconfig" > "$luo_config"
+	$make_cmd olddefconfig
+
+	# verify that kernel confiration has all necessary options
+	while read -r opt ; do
+		grep "$opt" "$kconfig" &>/dev/null || skip "$opt is missing"
+	done < "$luo_config"
+
+	$make_cmd "$kimage"
+	$make_cmd headers_install INSTALL_HDR_PATH="$headers_dir"
+}
+
+function mkinitrd() {
+	local build_dir=$1
+	local kernel_path=$2
+	local test_name=$3
+
+	# Compile the test binary and the init process
+	"$CROSS_COMPILE"gcc -static -O2 -nostdinc -nostdlib \
+		-I "$headers_dir/include" \
+		-I "$kernel_dir/tools/include/nolibc" \
+		-I "$test_dir" \
+		-o "$workspace_dir/test_binary" \
+		"$test_dir/$test_name.c" "$test_dir/luo_test_utils.c"
+
+	"$CROSS_COMPILE"gcc -s -static -Os -nostdinc -nostdlib		\
+			-fno-asynchronous-unwind-tables -fno-ident	\
+			-fno-stack-protector				\
+			-I "$headers_dir/include"			\
+			-I "$kernel_dir/tools/include/nolibc"		\
+			-o "$workspace_dir/init" "$test_dir/init.c"
+
+	cat > "$workspace_dir/cpio_list_inner" <<EOF
+dir /dev 0755 0 0
+dir /proc 0755 0 0
+dir /debugfs 0755 0 0
+nod /dev/console 0600 0 0 c 5 1
+file /init $workspace_dir/init 0755 0 0
+file /test_binary $workspace_dir/test_binary 0755 0 0
+EOF
+
+	# Generate inner_initrd.cpio
+	"$build_dir/usr/gen_init_cpio" "$workspace_dir/cpio_list_inner" > "$workspace_dir/inner_initrd.cpio"
+
+	cat > "$workspace_dir/cpio_list" <<EOF
+dir /dev 0755 0 0
+dir /proc 0755 0 0
+dir /debugfs 0755 0 0
+nod /dev/console 0600 0 0 c 5 1
+file /init $workspace_dir/init 0755 0 0
+file /kernel $kernel_path 0644 0 0
+file /test_binary $workspace_dir/test_binary 0755 0 0
+file /initrd.img $workspace_dir/inner_initrd.cpio 0644 0 0
+EOF
+
+	# Generate the final initrd
+	"$build_dir/usr/gen_init_cpio" "$workspace_dir/cpio_list" > "$initrd"
+}
+
+function run_qemu() {
+	local qemu_cmd=$1
+	local cmdline=$2
+	local kernel_path=$3
+	local serial="$workspace_dir/qemu.serial"
+
+	cmdline="$cmdline liveupdate=on panic=-1"
+
+	echo "# Serial Log: $serial"
+	timeout 30s \
+	$qemu_cmd -m 1G -smp 2 -no-reboot -nographic -nodefaults \
+		  -accel tcg -accel hvf -accel kvm \
+		  -serial file:"$serial" \
+		  -append "$cmdline" \
+		  -kernel "$kernel_path" \
+		  -initrd "$initrd"
+
+	grep "TEST PASSED" "$serial" &> /dev/null || fail "Liveupdate failed"
+}
+
+function target_to_arch() {
+	local target=$1
+	case $target in
+	     aarch64) echo "arm64" ;;
+	     x86_64) echo "x86" ;;
+	     *) skip "architecture $target is not supported"
+	esac
+}
+
+function main() {
+	local build_dir=""
+	local jobs=$(nproc)
+	local target="$(uname -m)"
+	local test_name="luo_kexec_simple"
+	local workspace_arg=""
+
+	set -o errtrace
+	trap fail ERR
+
+	while getopts 'hd:j:t:T:w:k' opt; do
+		case $opt in
+		d) build_dir="$OPTARG" ;;
+		j) jobs="$OPTARG" ;;
+		t) target="$OPTARG" ;;
+		T) test_name="$OPTARG" ;;
+		w) workspace_arg="$OPTARG" ;;
+		k) KEEP_WORKSPACE=1 ;;
+		h) usage; exit 0 ;;
+		*) echo "Unknown argument $opt"; usage; exit 1 ;;
+		esac
+	done
+
+	ktap_print_header
+	ktap_set_plan 1
+	trap cleanup EXIT
+
+	if [ -n "$workspace_arg" ]; then
+		workspace_dir="$(realpath -m "$workspace_arg")"
+		mkdir -p "$workspace_dir"
+	else
+		workspace_dir=$(mktemp -d /tmp/luo-test.XXXXXXXX)
+	fi
+
+	echo "# Workspace created at: $workspace_dir"
+	headers_dir="$workspace_dir/usr"
+	initrd="$workspace_dir/initrd.cpio"
+
+	detect_cross_compile "$target"
+
+	local arch=$(target_to_arch "$target")
+
+	if [ -z "$build_dir" ]; then
+		build_dir="$kernel_dir/.luo_test_build.$arch"
+	fi
+
+	mkdir -p "$build_dir"
+	build_dir=$(realpath "$build_dir")
+	get_arch_conf "$arch"
+
+	local make_cmd="make -s ARCH=$arch CROSS_COMPILE=$CROSS_COMPILE -j$jobs"
+	local make_cmd_build="$make_cmd -C $kernel_dir O=$build_dir"
+
+	build_kernel "$build_dir" "$make_cmd_build" "$KERNEL_IMAGE" "$target"
+
+	local final_kernel="$build_dir/arch/$arch/boot/$KERNEL_IMAGE"
+	mkinitrd "$build_dir" "$final_kernel" "$test_name"
+
+	run_qemu "$QEMU_CMD" "$KERNEL_CMDLINE" "$final_kernel"
+	ktap_test_pass "$test_name succeeded"
+}
+
+main "$@"