diff --git a/hypervisor/boot/guest/vboot_info.c b/hypervisor/boot/guest/vboot_info.c
index 6059ef71f..249670903 100644
--- a/hypervisor/boot/guest/vboot_info.c
+++ b/hypervisor/boot/guest/vboot_info.c
@@ -28,15 +28,16 @@
 /**
  * @pre vm != NULL && mbi != NULL
  */
-static void init_vm_ramdisk_info(struct acrn_vm *vm, struct multiboot_module *mod)
+static void init_vm_ramdisk_info(struct acrn_vm *vm, const struct multiboot_module *mod)
 {
 	void *mod_addr = hpa2hva((uint64_t)mod->mm_mod_start);
-	uint32_t mod_size = mod->mm_mod_end - mod->mm_mod_start;
 
-	vm->sw.ramdisk_info.src_addr = mod_addr;
-	vm->sw.ramdisk_info.load_addr = vm->sw.kernel_info.kernel_load_addr + vm->sw.kernel_info.kernel_size;
-	vm->sw.ramdisk_info.load_addr = (void *)round_page_up((uint64_t)vm->sw.ramdisk_info.load_addr);
-	vm->sw.ramdisk_info.size = mod_size;
+	if ((mod_addr != NULL) && (mod->mm_mod_end > mod->mm_mod_start)) {
+		vm->sw.ramdisk_info.src_addr = mod_addr;
+		vm->sw.ramdisk_info.load_addr = vm->sw.kernel_info.kernel_load_addr + vm->sw.kernel_info.kernel_size;
+		vm->sw.ramdisk_info.load_addr = (void *)round_page_up((uint64_t)vm->sw.ramdisk_info.load_addr);
+		vm->sw.ramdisk_info.size = mod->mm_mod_end - mod->mm_mod_start;
+	}
 }
 
 /* There are two sources for sos_vm kernel cmdline:
@@ -88,6 +89,9 @@ static void merge_cmdline(const struct acrn_vm *vm, const char *cmdline, const c
 	}
 }
 
+/**
+ * @pre vm != NULL
+ */
 static void *get_kernel_load_addr(struct acrn_vm *vm)
 {
 	void *load_addr = NULL;
@@ -125,9 +129,9 @@ static void *get_kernel_load_addr(struct acrn_vm *vm)
 }
 
 /**
- * @pre vm != NULL && mbi != NULL
+ * @pre vm != NULL && mod != NULL
  */
-static int32_t init_vm_kernel_info(struct acrn_vm *vm, struct multiboot_module *mod)
+static int32_t init_vm_kernel_info(struct acrn_vm *vm, const struct multiboot_module *mod)
 {
 	struct acrn_vm_config *vm_config = get_vm_config(vm->vm_id);
 
@@ -136,8 +140,10 @@ static int32_t init_vm_kernel_info(struct acrn_vm *vm, struct multiboot_module *
 
 	vm->sw.kernel_type = vm_config->os_config.kernel_type;
 	vm->sw.kernel_info.kernel_src_addr = hpa2hva((uint64_t)mod->mm_mod_start);
-	vm->sw.kernel_info.kernel_size = mod->mm_mod_end - mod->mm_mod_start;
-	vm->sw.kernel_info.kernel_load_addr = get_kernel_load_addr(vm);
+	if ((vm->sw.kernel_info.kernel_src_addr != NULL) && (mod->mm_mod_end > mod->mm_mod_start)){
+		vm->sw.kernel_info.kernel_size = mod->mm_mod_end - mod->mm_mod_start;
+		vm->sw.kernel_info.kernel_load_addr = get_kernel_load_addr(vm);
+	}
 
 	return (vm->sw.kernel_info.kernel_load_addr == NULL) ? (-EINVAL) : 0;
 }
@@ -145,7 +151,7 @@ static int32_t init_vm_kernel_info(struct acrn_vm *vm, struct multiboot_module *
 /**
  * @pre vm != NULL && mbi != NULL
  */
-static void init_vm_bootargs_info(struct acrn_vm *vm, struct multiboot_info *mbi)
+static void init_vm_bootargs_info(struct acrn_vm *vm, const struct multiboot_info *mbi)
 {
 	struct acrn_vm_config *vm_config = get_vm_config(vm->vm_id);
 	char *bootargs = vm_config->os_config.bootargs;
@@ -171,27 +177,29 @@ static void init_vm_bootargs_info(struct acrn_vm *vm, struct multiboot_info *mbi
 	}
 
 	/* Kernel bootarg and zero page are right before the kernel image */
-	if (vm->sw.bootargs_info.size > 0) {
+	if (vm->sw.bootargs_info.size > 0U) {
 		vm->sw.bootargs_info.load_addr = vm->sw.kernel_info.kernel_load_addr - (MEM_1K * 8U);
 	} else {
 		vm->sw.bootargs_info.load_addr = NULL;
 	}
 }
 
-static uint32_t get_mod_idx_by_tag(struct multiboot_module *mods, uint32_t mods_count, const char *tag)
+/* @pre mods != NULL
+ */
+static uint32_t get_mod_idx_by_tag(const struct multiboot_module *mods, uint32_t mods_count, const char *tag)
 {
 	uint32_t i, ret = INVALID_MOD_IDX;
 	uint32_t tag_len = strnlen_s(tag, MAX_MOD_TAG_LEN);
 
-	for (i = 0; i < mods_count; i++) {
+	for (i = 0U; i < mods_count; i++) {
 		const char *mm_string = (char *)hpa2hva((uint64_t)mods[i].mm_string);
 		uint32_t mm_str_len = strnlen_s(mm_string, MAX_MOD_TAG_LEN);
 
 		/* when do file stitch by tool, the tag in mm_string might be followed with 0x0d or 0x0a */
 		if ((mm_str_len >= tag_len) && (strncmp(mm_string, tag, tag_len) == 0)
-				&& ((mm_string[tag_len] == 0x0d)
-				|| (mm_string[tag_len] == 0x0a)
-				|| (mm_string[tag_len] == 0))){
+				&& ((*(mm_string + tag_len) == 0x0d)
+				|| (*(mm_string + tag_len) == 0x0a)
+				|| (*(mm_string + tag_len) == 0))){
 			ret = i;
 			break;
 		}
@@ -201,7 +209,7 @@ static uint32_t get_mod_idx_by_tag(struct multiboot_module *mods, uint32_t mods_
 
 /* @pre vm != NULL && mbi != NULL
  */
-static int32_t init_vm_sw_load(struct acrn_vm *vm, struct multiboot_info *mbi)
+static int32_t init_vm_sw_load(struct acrn_vm *vm, const struct multiboot_info *mbi)
 {
 	struct acrn_vm_config *vm_config = get_vm_config(vm->vm_id);
 	struct multiboot_module *mods = (struct multiboot_module *)hpa2hva((uint64_t)mbi->mi_mods_addr);
@@ -210,9 +218,11 @@ static int32_t init_vm_sw_load(struct acrn_vm *vm, struct multiboot_info *mbi)
 
 	dev_dbg(ACRN_DBG_BOOT, "mod counts=%d\n", mbi->mi_mods_count);
 
-	mod_idx = get_mod_idx_by_tag(mods, mbi->mi_mods_count, vm_config->os_config.kernel_mod_tag);
-	if (mod_idx != INVALID_MOD_IDX) {
-		ret = init_vm_kernel_info(vm, &mods[mod_idx]);
+	if (mods != NULL) {
+		mod_idx = get_mod_idx_by_tag(mods, mbi->mi_mods_count, vm_config->os_config.kernel_mod_tag);
+		if (mod_idx != INVALID_MOD_IDX) {
+			ret = init_vm_kernel_info(vm, &mods[mod_idx]);
+		}
 	}
 
 	if (ret == 0) {
diff --git a/hypervisor/common/vm_load.c b/hypervisor/common/vm_load.c
index 8c587f36c..696a7ce69 100644
--- a/hypervisor/common/vm_load.c
+++ b/hypervisor/common/vm_load.c
@@ -50,6 +50,9 @@ static uint32_t create_zeropage_e820(struct zero_page *zp, const struct acrn_vm
 	return entry_num;
 }
 
+/**
+ * @pre vm != NULL
+ */
 static uint64_t create_zero_page(struct acrn_vm *vm)
 {
 	struct zero_page *zeropage;
@@ -98,6 +101,9 @@ static uint64_t create_zero_page(struct acrn_vm *vm)
 	return gpa;
 }
 
+/**
+ * @pre vm != NULL
+ */
 static void prepare_loading_bzimage(struct acrn_vm *vm, struct acrn_vcpu *vcpu)
 {
 	uint32_t i;
@@ -150,6 +156,9 @@ static void prepare_loading_bzimage(struct acrn_vm *vm, struct acrn_vcpu *vcpu)
 			__func__, vm->vm_id, vcpu_get_gpreg(vcpu, CPU_REG_RSI));
 }
 
+/**
+ * @pre vm != NULL
+ */
 static void prepare_loading_rawimage(struct acrn_vm *vm)
 {
 	struct sw_kernel_info *sw_kernel = &(vm->sw.kernel_info);
@@ -158,6 +167,9 @@ static void prepare_loading_rawimage(struct acrn_vm *vm)
 	sw_kernel->kernel_entry_addr = (void *)vm_config->os_config.kernel_entry_addr;
 }
 
+/**
+ * @pre vm != NULL
+ */
 int32_t direct_boot_sw_loader(struct acrn_vm *vm)
 {
 	int32_t ret = 0;