diff --git a/hypervisor/arch/x86/configs/pci_dev.c b/hypervisor/arch/x86/configs/pci_dev.c
index 190d5ba91..4bba7c4df 100644
--- a/hypervisor/arch/x86/configs/pci_dev.c
+++ b/hypervisor/arch/x86/configs/pci_dev.c
@@ -65,7 +65,7 @@ struct acrn_vm_pci_dev_config *init_one_dev_config(struct pci_pdev *pdev)
 
 			dev_config = &vm_config->pci_devs[vm_config->pci_dev_num];
 			if (is_hv_owned_pdev(pdev->bdf)) {
-				/* SOS need to emulate the type1 pdevs owned by HV */
+				/* Service VM need to emulate the type1 pdevs owned by HV */
 				dev_config->emu_type = PCI_DEV_TYPE_SOSEMUL;
 				if (is_bridge(pdev)) {
 					dev_config->vdev_ops = &vpci_bridge_ops;
diff --git a/hypervisor/arch/x86/e820.c b/hypervisor/arch/x86/e820.c
index 9d8d95a0b..a68ca6a13 100644
--- a/hypervisor/arch/x86/e820.c
+++ b/hypervisor/arch/x86/e820.c
@@ -16,7 +16,7 @@
 
 /*
  * e820.c contains the related e820 operations; like HV to get memory info for its MMU setup;
- * and hide HV memory from SOS_VM...
+ * and hide HV memory from Service VM...
  */
 
 static uint32_t hv_e820_entries_nr;
@@ -26,7 +26,7 @@ static struct e820_entry hv_e820[E820_MAX_ENTRIES];
 #define DBG_LEVEL_E820	6U
 
 /*
- * @brief reserve some RAM, hide it from sos_vm, return its start address
+ * @brief reserve some RAM, hide it from Service VM, return its start address
  * @param size_arg Amount of memory to be found and marked reserved
  * @param max_addr Maximum address below which memory is to be identified
  *
diff --git a/hypervisor/arch/x86/guest/assign.c b/hypervisor/arch/x86/guest/assign.c
index 3f4b315af..ac485e4d9 100644
--- a/hypervisor/arch/x86/guest/assign.c
+++ b/hypervisor/arch/x86/guest/assign.c
@@ -290,7 +290,7 @@ ptirq_build_physical_rte(struct acrn_vm *vm, struct ptirq_remapping_info *entry)
 
 /* add msix entry for a vm, based on msi id (phys_bdf+msix_index)
  * - if the entry not be added by any vm, allocate it
- * - if the entry already be added by sos_vm, then change the owner to current vm
+ * - if the entry already be added by Service VM, then change the owner to current vm
  * - if the entry already be added by other vm, return NULL
  */
 static struct ptirq_remapping_info *add_msix_remapping(struct acrn_vm *vm,
@@ -351,7 +351,7 @@ remove_msix_remapping(const struct acrn_vm *vm, uint16_t phys_bdf, uint32_t entr
 
 /* add intx entry for a vm, based on intx id (phys_pin)
  * - if the entry not be added by any vm, allocate it
- * - if the entry already be added by sos_vm, then change the owner to current vm
+ * - if the entry already be added by Service VM, then change the owner to current vm
  * - if the entry already be added by other vm, return NULL
  */
 static struct ptirq_remapping_info *add_intx_remapping(struct acrn_vm *vm, uint32_t virt_gsi,
@@ -398,7 +398,7 @@ static struct ptirq_remapping_info *add_intx_remapping(struct acrn_vm *vm, uint3
 
 
 	/*
-	 * ptirq entry is either created or transferred from SOS VM to Post-launched VM
+	 * ptirq entry is either created or transferred from Service VM to Post-launched VM
 	 */
 
 	if (entry != NULL) {
@@ -781,7 +781,7 @@ int32_t ptirq_intx_pin_remap(struct acrn_vm *vm, uint32_t virt_gsi, enum intx_ct
 }
 
 /* @pre vm != NULL
- * except sos_vm, Device Model should call this function to pre-hold ptdev intx
+ * except Service VM, Device Model should call this function to pre-hold ptdev intx
  * entries:
  * - the entry is identified by phys_pin:
  *   one entry vs. one phys_pin
diff --git a/hypervisor/arch/x86/guest/ept.c b/hypervisor/arch/x86/guest/ept.c
index 3e24c8a0b..84ac25d6b 100644
--- a/hypervisor/arch/x86/guest/ept.c
+++ b/hypervisor/arch/x86/guest/ept.c
@@ -184,8 +184,8 @@ void init_ept_pgtable(struct pgtable *table, uint16_t vm_id)
 	}
 }
 /*
- * To enable the identical map and support of legacy devices/ACPI method in SOS,
- * ACRN presents the entire host 0-4GB memory region to SOS, except the memory
+ * To enable the identical map and support of legacy devices/ACPI method in Service VM,
+ * ACRN presents the entire host 0-4GB memory region to Service VM, except the memory
  * regions explicitly assigned to pre-launched VMs or HV (DRAM and MMIO). However,
  * virtual e820 only contains the known DRAM regions. For this reason,
  * we can't know if the GPA range is guest valid or not, by checking with
@@ -260,9 +260,9 @@ uint64_t gpa2hpa(struct acrn_vm *vm, uint64_t gpa)
 }
 
 /**
- * @pre: the gpa and hpa are identical mapping in SOS.
+ * @pre: the gpa and hpa are identical mapping in Service VM.
  */
-uint64_t sos_vm_hpa2gpa(uint64_t hpa)
+uint64_t service_vm_hpa2gpa(uint64_t hpa)
 {
 	return hpa;
 }
diff --git a/hypervisor/arch/x86/guest/pm.c b/hypervisor/arch/x86/guest/pm.c
index 0f3453481..2a7b91c92 100644
--- a/hypervisor/arch/x86/guest/pm.c
+++ b/hypervisor/arch/x86/guest/pm.c
@@ -183,7 +183,7 @@ static inline void enter_s3(struct acrn_vm *vm, uint32_t pm1a_cnt_val, uint32_t
 	guest_wakeup_vec32 = *(vm->pm.sx_state_data->wake_vector_32);
 	clac();
 
-	pause_vm(vm);	/* pause sos_vm before suspend system */
+	pause_vm(vm);	/* pause Service VM before suspend system */
 	host_enter_s3(vm->pm.sx_state_data, pm1a_cnt_val, pm1b_cnt_val);
 	resume_vm_from_s3(vm, guest_wakeup_vec32);	/* jump back to vm */
 	put_vm_lock(vm);
diff --git a/hypervisor/arch/x86/guest/ve820.c b/hypervisor/arch/x86/guest/ve820.c
index f8b8dbf25..f95bf5df1 100644
--- a/hypervisor/arch/x86/guest/ve820.c
+++ b/hypervisor/arch/x86/guest/ve820.c
@@ -18,7 +18,7 @@
 #define ENTRY_HPA1_LOW_PART2	5U
 #define ENTRY_HPA1_HI		9U
 
-static struct e820_entry sos_vm_e820[E820_MAX_ENTRIES];
+static struct e820_entry service_vm_e820[E820_MAX_ENTRIES];
 static struct e820_entry pre_vm_e820[PRE_VM_NUM][E820_MAX_ENTRIES];
 
 uint64_t find_space_from_ve820(struct acrn_vm *vm, uint32_t size, uint64_t min_addr, uint64_t max_addr)
@@ -70,7 +70,7 @@ static void sort_vm_e820(struct acrn_vm *vm)
 	}
 }
 
-static void filter_mem_from_sos_e820(struct acrn_vm *vm, uint64_t start_pa, uint64_t end_pa)
+static void filter_mem_from_service_vm_e820(struct acrn_vm *vm, uint64_t start_pa, uint64_t end_pa)
 {
 	uint32_t i;
 	uint64_t entry_start;
@@ -79,7 +79,7 @@ static void filter_mem_from_sos_e820(struct acrn_vm *vm, uint64_t start_pa, uint
 	struct e820_entry *entry, new_entry = {0};
 
 	for (i = 0U; i < entries_count; i++) {
-		entry = &sos_vm_e820[i];
+		entry = &service_vm_e820[i];
 		entry_start = entry->baseaddr;
 		entry_end = entry->baseaddr + entry->length;
 
@@ -121,7 +121,7 @@ static void filter_mem_from_sos_e820(struct acrn_vm *vm, uint64_t start_pa, uint
 	if (new_entry.length > 0UL) {
 		entries_count++;
 		ASSERT(entries_count <= E820_MAX_ENTRIES, "e820 entry overflow");
-		entry = &sos_vm_e820[entries_count - 1U];
+		entry = &service_vm_e820[entries_count - 1U];
 		entry->baseaddr = new_entry.baseaddr;
 		entry->length = new_entry.length;
 		entry->type = new_entry.type;
@@ -131,46 +131,46 @@ static void filter_mem_from_sos_e820(struct acrn_vm *vm, uint64_t start_pa, uint
 }
 
 /**
- * before boot sos_vm(service OS), call it to hide HV and prelaunched VM memory in e820 table from sos_vm
+ * before boot Service VM, call it to hide HV and prelaunched VM memory in e820 table from Service VM
  *
  * @pre vm != NULL
  */
-void create_sos_vm_e820(struct acrn_vm *vm)
+void create_service_vm_e820(struct acrn_vm *vm)
 {
 	uint16_t vm_id, i;
 	uint64_t hv_start_pa = hva2hpa((void *)(get_hv_image_base()));
 	uint64_t hv_end_pa  = hv_start_pa + get_hv_ram_size();
 	uint32_t entries_count = get_e820_entries_count();
-	struct acrn_vm_config *sos_vm_config = get_vm_config(vm->vm_id);
+	struct acrn_vm_config *service_vm_config = get_vm_config(vm->vm_id);
 
-	(void)memcpy_s((void *)sos_vm_e820, entries_count * sizeof(struct e820_entry),
+	(void)memcpy_s((void *)service_vm_e820, entries_count * sizeof(struct e820_entry),
 			(const void *)get_e820_entry(), entries_count * sizeof(struct e820_entry));
 
 	vm->e820_entry_num = entries_count;
-	vm->e820_entries = sos_vm_e820;
+	vm->e820_entries = service_vm_e820;
 	/* filter out hv memory from e820 table */
-	filter_mem_from_sos_e820(vm, hv_start_pa, hv_end_pa);
+	filter_mem_from_service_vm_e820(vm, hv_start_pa, hv_end_pa);
 
 	/* filter out prelaunched vm memory from e820 table */
 	for (vm_id = 0U; vm_id < CONFIG_MAX_VM_NUM; vm_id++) {
 		struct acrn_vm_config *vm_config = get_vm_config(vm_id);
 
 		if (vm_config->load_order == PRE_LAUNCHED_VM) {
-			filter_mem_from_sos_e820(vm, vm_config->memory.start_hpa,
+			filter_mem_from_service_vm_e820(vm, vm_config->memory.start_hpa,
 					vm_config->memory.start_hpa + vm_config->memory.size);
 
 			/* if HPA2 is available, filter it out as well*/
 			if (vm_config->memory.size_hpa2 != 0UL) {
-				filter_mem_from_sos_e820(vm, vm_config->memory.start_hpa2,
+				filter_mem_from_service_vm_e820(vm, vm_config->memory.start_hpa2,
 					vm_config->memory.start_hpa2 + vm_config->memory.size_hpa2);
 			}
 		}
 	}
 
 	for (i = 0U; i < vm->e820_entry_num; i++) {
-		struct e820_entry *entry = &sos_vm_e820[i];
+		struct e820_entry *entry = &service_vm_e820[i];
 		if ((entry->type == E820_TYPE_RAM)) {
-			sos_vm_config->memory.size += entry->length;
+			service_vm_config->memory.size += entry->length;
 		}
 	}
 	sort_vm_e820(vm);
diff --git a/hypervisor/arch/x86/guest/vept.c b/hypervisor/arch/x86/guest/vept.c
index 0fb30d1a6..ac5f43177 100644
--- a/hypervisor/arch/x86/guest/vept.c
+++ b/hypervisor/arch/x86/guest/vept.c
@@ -38,7 +38,7 @@ static uint64_t sept_page_bitmap[TOTAL_SEPT_4K_PAGES_NUM / 64U];
 
 /*
  * @brief Reserve space for SEPT 4K pages from platform E820 table
- * 	  At moment, we only support nested VMX for SOS VM.
+ * 	  At moment, we only support nested VMX for Service VM.
  */
 void reserve_buffer_for_sept_pages(void)
 {
diff --git a/hypervisor/arch/x86/guest/vlapic.c b/hypervisor/arch/x86/guest/vlapic.c
index 3d87f8258..38b9138ce 100644
--- a/hypervisor/arch/x86/guest/vlapic.c
+++ b/hypervisor/arch/x86/guest/vlapic.c
@@ -1889,7 +1889,7 @@ static int32_t inject_msi_for_non_lapic_pt(struct acrn_vm *vm, uint64_t addr, ui
 }
 
 /**
- *@pre Pointer vm shall point to SOS_VM
+ *@pre Pointer vm shall point to Service VM
  */
 static void inject_msi_for_lapic_pt(struct acrn_vm *vm, uint64_t addr, uint64_t data)
 {
diff --git a/hypervisor/arch/x86/guest/vm.c b/hypervisor/arch/x86/guest/vm.c
index 737583bdf..75ec4b976 100644
--- a/hypervisor/arch/x86/guest/vm.c
+++ b/hypervisor/arch/x86/guest/vm.c
@@ -46,15 +46,15 @@
 /* Local variables */
 
 /* pre-assumption: TRUSTY_RAM_SIZE is 2M aligned */
-static struct page post_uos_sworld_memory[MAX_POST_VM_NUM][TRUSTY_RAM_SIZE >> PAGE_SHIFT] __aligned(MEM_2M);
+static struct page post_user_vm_sworld_memory[MAX_POST_VM_NUM][TRUSTY_RAM_SIZE >> PAGE_SHIFT] __aligned(MEM_2M);
 
 static struct acrn_vm vm_array[CONFIG_MAX_VM_NUM] __aligned(PAGE_SIZE);
 
-static struct acrn_vm *sos_vm_ptr = NULL;
+static struct acrn_vm *service_vm_ptr = NULL;
 
 void *get_sworld_memory_base(void)
 {
-	return post_uos_sworld_memory;
+	return post_user_vm_sworld_memory;
 }
 
 uint16_t get_vmid_by_uuid(const uint8_t *uuid)
@@ -229,12 +229,12 @@ struct acrn_vm *get_vm_from_vmid(uint16_t vm_id)
 	return &vm_array[vm_id];
 }
 
-/* return a pointer to the virtual machine structure of SOS VM */
-struct acrn_vm *get_sos_vm(void)
+/* return a pointer to the virtual machine structure of Service VM */
+struct acrn_vm *get_service_vm(void)
 {
-	ASSERT(sos_vm_ptr != NULL, "sos_vm_ptr is NULL");
+	ASSERT(service_vm_ptr != NULL, "service_vm_ptr is NULL");
 
-	return sos_vm_ptr;
+	return service_vm_ptr;
 }
 
 /**
@@ -319,14 +319,14 @@ static void prepare_prelaunched_vm_memmap(struct acrn_vm *vm, const struct acrn_
 	}
 }
 
-static void deny_pci_bar_access(struct acrn_vm *sos, const struct pci_pdev *pdev)
+static void deny_pci_bar_access(struct acrn_vm *service_vm, const struct pci_pdev *pdev)
 {
 	uint32_t idx, mask;
 	struct pci_vbar vbar = {};
 	uint64_t base = 0UL, size = 0UL;
 	uint64_t *pml4_page;
 
-	pml4_page = (uint64_t *)sos->arch_vm.nworld_eptp;
+	pml4_page = (uint64_t *)service_vm->arch_vm.nworld_eptp;
 
 	for ( idx= 0; idx < pdev->nr_bars; idx++) {
 		vbar.bar_type.bits = pdev->bars[idx].phy_bar;
@@ -347,31 +347,31 @@ static void deny_pci_bar_access(struct acrn_vm *sos, const struct pci_pdev *pdev
 			if ((base != 0UL)) {
 				if (is_pci_io_bar(&vbar)) {
 					base &= 0xffffU;
-					deny_guest_pio_access(sos, base, size);
+					deny_guest_pio_access(service_vm, base, size);
 				} else {
 					/*for passthru device MMIO BAR base must be 4K aligned. This is the requirement of passthru devices.*/
 					ASSERT((base & PAGE_MASK) != 0U, "%02x:%02x.%d bar[%d] 0x%lx, is not 4K aligned!",
 						pdev->bdf.bits.b, pdev->bdf.bits.d, pdev->bdf.bits.f, idx, base);
 					size =  round_page_up(size);
-					ept_del_mr(sos, pml4_page, base, size);
+					ept_del_mr(service_vm, pml4_page, base, size);
 				}
 			}
 		}
 	}
 }
 
-static void deny_pdevs(struct acrn_vm *sos, struct acrn_vm_pci_dev_config *pci_devs, uint16_t pci_dev_num)
+static void deny_pdevs(struct acrn_vm *service_vm, struct acrn_vm_pci_dev_config *pci_devs, uint16_t pci_dev_num)
 {
 	uint16_t i;
 
 	for (i = 0; i < pci_dev_num; i++) {
 		if ( pci_devs[i].pdev != NULL) {
-			deny_pci_bar_access(sos, pci_devs[i].pdev);
+			deny_pci_bar_access(service_vm, pci_devs[i].pdev);
 		}
 	}
 }
 
-static void deny_hv_owned_devices(struct acrn_vm *sos)
+static void deny_hv_owned_devices(struct acrn_vm *service_vm)
 {
 	uint16_t pio_address;
 	uint32_t nbytes, i;
@@ -379,11 +379,11 @@ static void deny_hv_owned_devices(struct acrn_vm *sos)
 	const struct pci_pdev **hv_owned = get_hv_owned_pdevs();
 
 	for (i = 0U; i < get_hv_owned_pdev_num(); i++) {
-		deny_pci_bar_access(sos, hv_owned[i]);
+		deny_pci_bar_access(service_vm, hv_owned[i]);
 	}
 
 	if (get_pio_dbg_uart_cfg(&pio_address, &nbytes)) {
-		deny_guest_pio_access(sos, pio_address, nbytes);
+		deny_guest_pio_access(service_vm, pio_address, nbytes);
 	}
 }
 
@@ -395,12 +395,12 @@ static void deny_hv_owned_devices(struct acrn_vm *sos)
  * @pre vm != NULL
  * @pre is_service_vm(vm) == true
  */
-static void prepare_sos_vm_memmap(struct acrn_vm *vm)
+static void prepare_service_vm_memmap(struct acrn_vm *vm)
 {
 	uint16_t vm_id;
 	uint32_t i;
 	uint64_t hv_hpa;
-	uint64_t sos_high64_max_ram = MEM_4G;
+	uint64_t service_vm_high64_max_ram = MEM_4G;
 	struct acrn_vm_config *vm_config;
 	uint64_t *pml4_page = (uint64_t *)vm->arch_vm.nworld_eptp;
 	struct epc_section* epc_secs;
@@ -410,18 +410,18 @@ static void prepare_sos_vm_memmap(struct acrn_vm *vm)
 	const struct e820_entry *p_e820 = vm->e820_entries;
 	struct pci_mmcfg_region *pci_mmcfg;
 
-	pr_dbg("SOS_VM e820 layout:\n");
+	pr_dbg("Service VM e820 layout:\n");
 	for (i = 0U; i < entries_count; i++) {
 		entry = p_e820 + i;
 		pr_dbg("e820 table: %d type: 0x%x", i, entry->type);
 		pr_dbg("BaseAddress: 0x%016lx length: 0x%016lx\n", entry->baseaddr, entry->length);
 		if (entry->type == E820_TYPE_RAM) {
-			sos_high64_max_ram = max((entry->baseaddr + entry->length), sos_high64_max_ram);
+			service_vm_high64_max_ram = max((entry->baseaddr + entry->length), service_vm_high64_max_ram);
 		}
 	}
 
-	/* create real ept map for [0, sos_high64_max_ram) with UC */
-	ept_add_mr(vm, pml4_page, 0UL, 0UL, sos_high64_max_ram, EPT_RWX | EPT_UNCACHED);
+	/* create real ept map for [0, service_vm_high64_max_ram) with UC */
+	ept_add_mr(vm, pml4_page, 0UL, 0UL, service_vm_high64_max_ram, EPT_RWX | EPT_UNCACHED);
 
 	/* update ram entries to WB attr */
 	for (i = 0U; i < entries_count; i++) {
@@ -431,9 +431,9 @@ static void prepare_sos_vm_memmap(struct acrn_vm *vm)
 		}
 	}
 
-	/* Unmap all platform EPC resource from SOS.
+	/* Unmap all platform EPC resource from Service VM.
 	 * This part has already been marked as reserved by BIOS in E820
-	 * will cause EPT violation if sos accesses EPC resource.
+	 * will cause EPT violation if Service VM accesses EPC resource.
 	 */
 	epc_secs = get_phys_epc();
 	for (i = 0U; (i < MAX_EPC_SECTIONS) && (epc_secs[i].size != 0UL); i++) {
@@ -441,7 +441,7 @@ static void prepare_sos_vm_memmap(struct acrn_vm *vm)
 	}
 
 	/* unmap hypervisor itself for safety
-	 * will cause EPT violation if sos accesses hv memory
+	 * will cause EPT violation if Service VM accesses hv memory
 	 */
 	hv_hpa = hva2hpa((void *)(get_hv_image_base()));
 	ept_del_mr(vm, pml4_page, hv_hpa, get_hv_ram_size());
@@ -549,8 +549,8 @@ int32_t create_vm(uint16_t vm_id, uint64_t pcpu_bitmap, struct acrn_vm_config *v
 
 	if (is_service_vm(vm)) {
 		/* Only for Service VM */
-		create_sos_vm_e820(vm);
-		prepare_sos_vm_memmap(vm);
+		create_service_vm_e820(vm);
+		prepare_service_vm_memmap(vm);
 
 		status = init_vm_boot_info(vm);
 	} else {
@@ -559,11 +559,11 @@ int32_t create_vm(uint16_t vm_id, uint64_t pcpu_bitmap, struct acrn_vm_config *v
 			vm->sworld_control.flag.supported = 1U;
 		}
 		if (vm->sworld_control.flag.supported != 0UL) {
-			uint16_t sos_vm_id = (get_sos_vm())->vm_id;
-			uint16_t page_idx = vmid_2_rel_vmid(sos_vm_id, vm_id) - 1U;
+			uint16_t service_vm_id = (get_service_vm())->vm_id;
+			uint16_t page_idx = vmid_2_rel_vmid(service_vm_id, vm_id) - 1U;
 
 			ept_add_mr(vm, (uint64_t *)vm->arch_vm.nworld_eptp,
-				hva2hpa(post_uos_sworld_memory[page_idx]),
+				hva2hpa(post_user_vm_sworld_memory[page_idx]),
 				TRUSTY_EPT_REBASE_GPA, TRUSTY_RAM_SIZE, EPT_WB | EPT_RWX);
 		}
 		if (vm_config->name[0] == '\0') {
@@ -654,7 +654,7 @@ int32_t create_vm(uint16_t vm_id, uint64_t pcpu_bitmap, struct acrn_vm_config *v
 
 	if (status == 0) {
 		/* We have assumptions:
-		 *   1) vcpus used by SOS has been offlined by DM before UOS re-use it.
+		 *   1) vcpus used by Service VM has been offlined by DM before User VM re-use it.
 		 *   2) pcpu_bitmap passed sanitization is OK for vcpu creating.
 		 */
 		vm->hw.cpu_affinity = pcpu_bitmap;
@@ -907,7 +907,7 @@ void resume_vm_from_s3(struct acrn_vm *vm, uint32_t wakeup_vec)
 
 	reset_vcpu(bsp, POWER_ON_RESET);
 
-	/* When SOS resume from S3, it will return to real mode
+	/* When Service VM resume from S3, it will return to real mode
 	 * with entry set to wakeup_vec.
 	 */
 	set_vcpu_startup_entry(bsp, wakeup_vec);
@@ -930,7 +930,7 @@ void prepare_vm(uint16_t vm_id, struct acrn_vm_config *vm_config)
 #ifdef CONFIG_SECURITY_VM_FIXUP
 	security_vm_fixup(vm_id);
 #endif
-	/* SOS and pre-launched VMs launch on all pCPUs defined in vm_config->cpu_affinity */
+	/* Service VM and pre-launched VMs launch on all pCPUs defined in vm_config->cpu_affinity */
 	err = create_vm(vm_id, vm_config->cpu_affinity, vm_config, &vm);
 
 	if (err == 0) {
@@ -940,8 +940,8 @@ void prepare_vm(uint16_t vm_id, struct acrn_vm_config *vm_config)
 
 		if (is_service_vm(vm)) {
 			/* We need to ensure all modules of pre-launched VMs have been loaded already
-			 * before loading SOS VM modules, otherwise the module of pre-launched VMs could
-			 * be corrupted because SOS VM kernel might pick any usable RAM to extract kernel
+			 * before loading Service VM modules, otherwise the module of pre-launched VMs could
+			 * be corrupted because Service VM kernel might pick any usable RAM to extract kernel
 			 * when KASLR enabled.
 			 * In case the pre-launched VMs aren't loaded successfuly that cause deadlock here,
 			 * use a 10000ms timer to break the waiting loop.
@@ -990,7 +990,7 @@ void launch_vms(uint16_t pcpu_id)
 		if ((vm_config->load_order == SOS_VM) || (vm_config->load_order == PRE_LAUNCHED_VM)) {
 			if (pcpu_id == get_configured_bsp_pcpu_id(vm_config)) {
 				if (vm_config->load_order == SOS_VM) {
-					sos_vm_ptr = &vm_array[vm_id];
+					service_vm_ptr = &vm_array[vm_id];
 				}
 				prepare_vm(vm_id, vm_config);
 			}
diff --git a/hypervisor/arch/x86/guest/vm_reset.c b/hypervisor/arch/x86/guest/vm_reset.c
index 7da35a61a..65e4aba04 100644
--- a/hypervisor/arch/x86/guest/vm_reset.c
+++ b/hypervisor/arch/x86/guest/vm_reset.c
@@ -28,7 +28,7 @@ void triple_fault_shutdown_vm(struct acrn_vcpu *vcpu)
 		io_req->reqs.pio_request.size = 2UL;
 		io_req->reqs.pio_request.value = (VIRTUAL_PM1A_SLP_EN | (5U << 10U));
 
-		/* Inject pm1a S5 request to SOS to shut down the guest */
+		/* Inject pm1a S5 request to Service VM to shut down the guest */
 		(void)emulate_io(vcpu, io_req);
 	} else {
 		if (is_service_vm(vm)) {
@@ -47,7 +47,7 @@ void triple_fault_shutdown_vm(struct acrn_vcpu *vcpu)
 			}
 		}
 
-		/* Either SOS or pre-launched VMs */
+		/* Either Service VM or pre-launched VMs */
 		get_vm_lock(vm);
 		poweroff_if_rt_vm(vm);
 		pause_vm(vm);
@@ -101,7 +101,7 @@ static bool handle_common_reset_reg_write(struct acrn_vcpu *vcpu, bool reset)
 			ret = false;
 		} else {
 			/*
-			 * If it's SOS reset while RTVM is still alive
+			 * If it's Service VM reset while RTVM is still alive
 			 *    or pre-launched VM reset,
 			 * ACRN doesn't support re-launch, just shutdown the guest.
 			 */
@@ -116,7 +116,7 @@ static bool handle_common_reset_reg_write(struct acrn_vcpu *vcpu, bool reset)
 			ret = false;
 		}
 		/*
-		 * Ignore writes from SOS and pre-launched VM.
+		 * Ignore writes from Service VM and pre-launched VM.
 		 * Equivalent to hiding this port from the guest.
 		 */
 	}
@@ -198,7 +198,7 @@ static bool handle_reset_reg_write(struct acrn_vcpu *vcpu, uint16_t addr, size_t
  */
 void register_reset_port_handler(struct acrn_vm *vm)
 {
-	/* Don't support SOS and pre-launched VM re-launch for now. */
+	/* Don't support Service VM and pre-launched VM re-launch for now. */
 	if (!is_postlaunched_vm(vm) || is_rt_vm(vm)) {
 		struct acpi_reset_reg *reset_reg = get_host_reset_reg_data();
 		struct acrn_acpi_generic_address *gas = &(reset_reg->reg);
@@ -215,7 +215,7 @@ void register_reset_port_handler(struct acrn_vm *vm)
 		register_pio_emulation_handler(vm, CF9_PIO_IDX, &io_range, handle_reset_reg_read, handle_cf9_write);
 
 		/*
-		 * - here is taking care of SOS only:
+		 * - here is taking care of Service VM only:
 		 *   Don't support MMIO or PCI based reset register for now.
 		 *   ACPI Spec: Register_Bit_Width must be 8 and Register_Bit_Offset must be 0.
 		 */
diff --git a/hypervisor/arch/x86/guest/vmcall.c b/hypervisor/arch/x86/guest/vmcall.c
index 7c2ebc02f..0cd5a3ea1 100644
--- a/hypervisor/arch/x86/guest/vmcall.c
+++ b/hypervisor/arch/x86/guest/vmcall.c
@@ -20,7 +20,8 @@ struct hc_dispatch {
 
 	/* The permission_flags is a bitmap of guest flags indicating whether a VM can invoke this hypercall:
 	 *
-	 * - If permission_flags == 0UL (which is the default value), this hypercall can only be invoked by the SOS.
+	 * - If permission_flags == 0UL (which is the default value), this hypercall can only be invoked by the
+	 *   Service VM.
 	 * - Otherwise, this hypercall can only be invoked by a VM whose guest flags have ALL set bits in
 	 *   permission_flags.
 	 */
@@ -31,8 +32,8 @@ struct hc_dispatch {
 static const struct hc_dispatch hc_dispatch_table[] = {
 	[HC_IDX(HC_GET_API_VERSION)] = {
 		.handler = hcall_get_api_version},
-	[HC_IDX(HC_SOS_OFFLINE_CPU)] = {
-		.handler = hcall_sos_offline_cpu},
+	[HC_IDX(HC_SERVICE_VM_OFFLINE_CPU)] = {
+		.handler = hcall_service_vm_offline_cpu},
 	[HC_IDX(HC_SET_CALLBACK_VECTOR)] = {
 		.handler = hcall_set_callback_vector},
 	[HC_IDX(HC_GET_PLATFORM_INFO)] = {
@@ -106,7 +107,7 @@ static const struct hc_dispatch hc_dispatch_table[] = {
 
 #define GUEST_FLAGS_ALLOWING_HYPERCALLS GUEST_FLAG_SECURE_WORLD_ENABLED
 
-struct acrn_vm *parse_target_vm(struct acrn_vm *sos_vm, uint64_t hcall_id, uint64_t param1, __unused uint64_t param2)
+struct acrn_vm *parse_target_vm(struct acrn_vm *service_vm, uint64_t hcall_id, uint64_t param1, __unused uint64_t param2)
 {
 	struct acrn_vm *target_vm = NULL;
 	uint16_t vm_id = ACRN_INVALID_VMID;
@@ -116,34 +117,34 @@ struct acrn_vm *parse_target_vm(struct acrn_vm *sos_vm, uint64_t hcall_id, uint6
 
 	switch (hcall_id) {
 	case HC_CREATE_VM:
-		if (copy_from_gpa(sos_vm, &cv, param1, sizeof(cv)) == 0) {
+		if (copy_from_gpa(service_vm, &cv, param1, sizeof(cv)) == 0) {
 			vm_id = get_vmid_by_uuid(&cv.uuid[0]);
 		}
 		break;
 
 	case HC_PM_GET_CPU_STATE:
-		vm_id = rel_vmid_2_vmid(sos_vm->vm_id, (uint16_t)((param1 & PMCMD_VMID_MASK) >> PMCMD_VMID_SHIFT));
+		vm_id = rel_vmid_2_vmid(service_vm->vm_id, (uint16_t)((param1 & PMCMD_VMID_MASK) >> PMCMD_VMID_SHIFT));
 		break;
 
 	case HC_VM_SET_MEMORY_REGIONS:
-		if (copy_from_gpa(sos_vm, &regions, param1, sizeof(regions)) == 0) {
+		if (copy_from_gpa(service_vm, &regions, param1, sizeof(regions)) == 0) {
 			/* the vmid in regions is a relative vm id, need to convert to absolute vm id */
-			vm_id = rel_vmid_2_vmid(sos_vm->vm_id, regions.vmid);
+			vm_id = rel_vmid_2_vmid(service_vm->vm_id, regions.vmid);
 		}
 		break;
 	case HC_GET_API_VERSION:
-	case HC_SOS_OFFLINE_CPU:
+	case HC_SERVICE_VM_OFFLINE_CPU:
 	case HC_SET_CALLBACK_VECTOR:
 	case HC_GET_PLATFORM_INFO:
 	case HC_SETUP_SBUF:
 	case HC_SETUP_HV_NPK_LOG:
 	case HC_PROFILING_OPS:
 	case HC_GET_HW_INFO:
-		target_vm = sos_vm;
+		target_vm = service_vm;
 		break;
 	default:
 		relative_vm_id = (uint16_t)param1;
-		vm_id = rel_vmid_2_vmid(sos_vm->vm_id, relative_vm_id);
+		vm_id = rel_vmid_2_vmid(service_vm->vm_id, relative_vm_id);
 		break;
 	}
 
@@ -173,7 +174,7 @@ static int32_t dispatch_hypercall(struct acrn_vcpu *vcpu)
 			uint64_t param2 = vcpu_get_gpreg(vcpu, CPU_REG_RSI);  /* hypercall param2 from guest */
 
 			if ((permission_flags == 0UL) && is_service_vm(vm)) {
-				/* A permission_flags of 0 indicates that this hypercall is for SOS to manage
+				/* A permission_flags of 0 indicates that this hypercall is for Service VM to manage
 				 * post-launched VMs.
 				 */
 				struct acrn_vm *target_vm = parse_target_vm(vm, hcall_id, param1, param2);
@@ -198,7 +199,7 @@ static int32_t dispatch_hypercall(struct acrn_vcpu *vcpu)
 }
 
 /*
- * Pass return value to SOS by register rax.
+ * Pass return value to Service VM by register rax.
  * This function should always return 0 since we shouldn't
  * deal with hypercall error in hypervisor.
  */
@@ -213,7 +214,7 @@ int32_t vmcall_vmexit_handler(struct acrn_vcpu *vcpu)
 	/*
 	 * The following permission checks are applied to hypercalls.
 	 *
-	 * 1. Only SOS and VMs with specific guest flags (referred to as 'allowed VMs' hereinafter) can invoke
+	 * 1. Only Service VM and VMs with specific guest flags (referred to as 'allowed VMs' hereinafter) can invoke
 	 *    hypercalls by executing the `vmcall` instruction. Attempts to execute the `vmcall` instruction in the
 	 *    other VMs will trigger #UD.
 	 * 2. Attempts to execute the `vmcall` instruction from ring 1, 2 or 3 in an allowed VM will trigger #GP(0).
diff --git a/hypervisor/arch/x86/guest/vmsr.c b/hypervisor/arch/x86/guest/vmsr.c
index a92f28fa0..c5ed1d1eb 100644
--- a/hypervisor/arch/x86/guest/vmsr.c
+++ b/hypervisor/arch/x86/guest/vmsr.c
@@ -976,7 +976,7 @@ int32_t wrmsr_vmexit_handler(struct acrn_vcpu *vcpu)
 	}
 	case MSR_IA32_BIOS_UPDT_TRIG:
 	{
-		/* We only allow SOS to do uCode update */
+		/* We only allow Service VM to do uCode update */
 		if (is_service_vm(vcpu->vm)) {
 			acrn_update_ucode(vcpu, v);
 		}
diff --git a/hypervisor/arch/x86/guest/vmtrr.c b/hypervisor/arch/x86/guest/vmtrr.c
index 8b70fa1dc..f7723cede 100644
--- a/hypervisor/arch/x86/guest/vmtrr.c
+++ b/hypervisor/arch/x86/guest/vmtrr.c
@@ -115,7 +115,7 @@ void init_vmtrr(struct acrn_vcpu *vcpu)
 	for (i = 0U; i < FIXED_RANGE_MTRR_NUM; i++) {
 		if (cap.bits.fix != 0U) {
 			/*
-			 * The system firmware runs in VMX non-root mode on SOS_VM.
+			 * The system firmware runs in VMX non-root mode on Service VM.
 			 * In some cases, the firmware needs particular mem type
 			 * at certain mmeory locations (e.g. UC for some
 			 * hardware registers), so we need to configure EPT
@@ -124,7 +124,7 @@ void init_vmtrr(struct acrn_vcpu *vcpu)
 			vmtrr->fixed_range[i].value = msr_read(fixed_mtrr_map[i].msr);
 		} else {
 			/*
-			 * For non-sos_vm EPT, all memory is setup with WB type in
+			 * For non-Service VM EPT, all memory is setup with WB type in
 			 * EPT, so we setup fixed range MTRRs accordingly.
 			 */
 			vmtrr->fixed_range[i].value = MTRR_FIXED_RANGE_ALL_WB;
diff --git a/hypervisor/arch/x86/guest/vmx_io.c b/hypervisor/arch/x86/guest/vmx_io.c
index 63a311d57..5b7b55a92 100644
--- a/hypervisor/arch/x86/guest/vmx_io.c
+++ b/hypervisor/arch/x86/guest/vmx_io.c
@@ -21,14 +21,14 @@
 void arch_fire_hsm_interrupt(void)
 {
 	/*
-	 * use vLAPIC to inject vector to SOS vcpu 0 if vlapic is enabled
+	 * use vLAPIC to inject vector to Service VM vcpu 0 if vlapic is enabled
 	 * otherwise, send IPI hardcoded to BSP_CPU_ID
 	 */
-	struct acrn_vm *sos_vm;
+	struct acrn_vm *service_vm;
 	struct acrn_vcpu *vcpu;
 
-	sos_vm = get_sos_vm();
-	vcpu = vcpu_from_vid(sos_vm, BSP_CPU_ID);
+	service_vm = get_service_vm();
+	vcpu = vcpu_from_vid(service_vm, BSP_CPU_ID);
 
 	vlapic_set_intr(vcpu, get_hsm_notification_vector(), LAPIC_TRIG_EDGE);
 }
diff --git a/hypervisor/arch/x86/notify.c b/hypervisor/arch/x86/notify.c
index ef9ccfeeb..b8efb5bf6 100644
--- a/hypervisor/arch/x86/notify.c
+++ b/hypervisor/arch/x86/notify.c
@@ -89,7 +89,7 @@ static int32_t request_notification_irq(irq_action_t func, void *data)
  */
 void setup_notification(void)
 {
-	/* support IPI notification, SOS_VM will register all CPU */
+	/* support IPI notification, Service VM will register all CPU */
 	if (request_notification_irq(kick_notification, NULL) < 0) {
 		pr_err("Failed to setup notification");
 	}
diff --git a/hypervisor/arch/x86/seed/seed.c b/hypervisor/arch/x86/seed/seed.c
index 950dd51e7..a57d1e416 100644
--- a/hypervisor/arch/x86/seed/seed.c
+++ b/hypervisor/arch/x86/seed/seed.c
@@ -98,15 +98,15 @@ void fill_seed_arg(char *cmd_dst, size_t cmd_sz)
 	for (i = 0U; seed_arg[i].str != NULL; i++) {
 		if (seed_arg[i].addr != 0UL) {
 
-			snprintf(cmd_dst, cmd_sz, "%s0x%X ", seed_arg[i].str, sos_vm_hpa2gpa(seed_arg[i].addr));
+			snprintf(cmd_dst, cmd_sz, "%s0x%X ", seed_arg[i].str, service_vm_hpa2gpa(seed_arg[i].addr));
 
 			if (seed_arg[i].bootloader_id == BOOTLOADER_SBL) {
 				struct image_boot_params *boot_params =
 					(struct image_boot_params *)hpa2hva(seed_arg[i].addr);
 
-				boot_params->p_seed_list = sos_vm_hpa2gpa(boot_params->p_seed_list);
+				boot_params->p_seed_list = service_vm_hpa2gpa(boot_params->p_seed_list);
 
-				boot_params->p_platform_info = sos_vm_hpa2gpa(boot_params->p_platform_info);
+				boot_params->p_platform_info = service_vm_hpa2gpa(boot_params->p_platform_info);
 			}
 
 			break;
diff --git a/hypervisor/arch/x86/seed/seed_abl.c b/hypervisor/arch/x86/seed/seed_abl.c
index 212e14ffd..bb8ed25e2 100644
--- a/hypervisor/arch/x86/seed/seed_abl.c
+++ b/hypervisor/arch/x86/seed/seed_abl.c
@@ -68,7 +68,7 @@ bool parse_seed_abl(uint64_t addr, struct physical_seed *phy_seed)
 
 		/*
 		 * Copy out abl_seed for trusty and clear the original seed in memory.
-		 * The SOS requires the legacy seed to derive RPMB key. So skip the
+		 * The Service VM requires the legacy seed to derive RPMB key. So skip the
 		 * legacy seed when clear original seed.
 		 */
 		(void)memset((void *)&phy_seed->seed_list[0U], 0U, sizeof(phy_seed->seed_list));
diff --git a/hypervisor/boot/guest/bzimage_loader.c b/hypervisor/boot/guest/bzimage_loader.c
index 10141a81b..d6c8ebd12 100644
--- a/hypervisor/boot/guest/bzimage_loader.c
+++ b/hypervisor/boot/guest/bzimage_loader.c
@@ -72,14 +72,14 @@ static void *get_initrd_load_addr(struct acrn_vm *vm, uint64_t kernel_start)
 		uint64_t mods_start, mods_end;
 
 		get_boot_mods_range(&mods_start, &mods_end);
-		mods_start = sos_vm_hpa2gpa(mods_start);
-		mods_end = sos_vm_hpa2gpa(mods_end);
+		mods_start = service_vm_hpa2gpa(mods_start);
+		mods_end = service_vm_hpa2gpa(mods_end);
 
 		if (vm->sw.ramdisk_info.src_addr != NULL) {
-			ramdisk_load_gpa = sos_vm_hpa2gpa((uint64_t)vm->sw.ramdisk_info.src_addr);
+			ramdisk_load_gpa = service_vm_hpa2gpa((uint64_t)vm->sw.ramdisk_info.src_addr);
 		}
 
-		/* For SOS VM, the ramdisk has been loaded by bootloader, so in most cases
+		/* For Service VM, the ramdisk has been loaded by bootloader, so in most cases
 		 * there is no need to do gpa copy again. But in the case that the ramdisk is
 		 * loaded by bootloader at a address higher than its limit, we should do gpa
 		 * copy then.
@@ -150,8 +150,8 @@ static void *get_bzimage_kernel_load_addr(struct acrn_vm *vm)
 		uint32_t kernel_size = kernel_init_size + kernel_align;
 
 		get_boot_mods_range(&mods_start, &mods_end);
-		mods_start = sos_vm_hpa2gpa(mods_start);
-		mods_end = sos_vm_hpa2gpa(mods_end);
+		mods_start = service_vm_hpa2gpa(mods_start);
+		mods_end = service_vm_hpa2gpa(mods_end);
 
 		/* TODO: support load kernel when modules are beyond 4GB space. */
 		if (mods_end < MEM_4G) {
@@ -168,7 +168,7 @@ static void *get_bzimage_kernel_load_addr(struct acrn_vm *vm)
 	} else {
 		load_addr = (void *)zeropage->hdr.pref_addr;
 		if (is_service_vm(vm)) {
-			/* The non-relocatable SOS kernel might overlap with boot modules. */
+			/* The non-relocatable Servic VM kernel might overlap with boot modules. */
 			pr_err("Non-relocatable kernel found, risk to boot!");
 		}
 	}
@@ -185,13 +185,13 @@ static void *get_bzimage_kernel_load_addr(struct acrn_vm *vm)
 /**
  * @pre vm != NULL && efi_mmap_desc != NULL
  */
-static uint16_t create_sos_vm_efi_mmap_desc(struct acrn_vm *vm, struct efi_memory_desc *efi_mmap_desc)
+static uint16_t create_service_vm_efi_mmap_desc(struct acrn_vm *vm, struct efi_memory_desc *efi_mmap_desc)
 {
 	uint16_t i, desc_idx = 0U;
 	const struct efi_memory_desc *hv_efi_mmap_desc = get_efi_mmap_entry();
 
 	for (i = 0U; i < get_efi_mmap_entries_count(); i++) {
-		/* Below efi mmap desc types in native should be kept as original for SOS VM */
+		/* Below efi mmap desc types in native should be kept as original for Service VM */
 		if ((hv_efi_mmap_desc[i].type == EFI_RESERVED_MEMORYTYPE)
 				|| (hv_efi_mmap_desc[i].type == EFI_UNUSABLE_MEMORY)
 				|| (hv_efi_mmap_desc[i].type == EFI_ACPI_RECLAIM_MEMORY)
@@ -212,9 +212,9 @@ static uint16_t create_sos_vm_efi_mmap_desc(struct acrn_vm *vm, struct efi_memor
 
 	for (i = 0U; i < vm->e820_entry_num; i++) {
 		/* The memory region with e820 type of RAM could be acted as EFI_CONVENTIONAL_MEMORY
-		 * for SOS VM, the region which occupied by HV and pre-launched VM has been filtered
-		 * already, so it is safe for SOS VM.
-		 * As SOS VM start to run after efi call ExitBootService(), the type of EFI_LOADER_CODE
+		 * for Service VM, the region which occupied by HV and pre-launched VM has been filtered
+		 * already, so it is safe for Service VM.
+		 * As Service VM start to run after efi call ExitBootService(), the type of EFI_LOADER_CODE
 		 * and EFI_LOADER_DATA which have been mapped to E820_TYPE_RAM are not needed.
 		 */
 		if (vm->e820_entries[i].type == E820_TYPE_RAM) {
@@ -228,7 +228,7 @@ static uint16_t create_sos_vm_efi_mmap_desc(struct acrn_vm *vm, struct efi_memor
 	}
 
 	for (i = 0U; i < desc_idx; i++) {
-		pr_dbg("SOS VM efi mmap desc[%d]: addr: 0x%lx, len: 0x%lx, type: %d", i,
+		pr_dbg("Service VM efi mmap desc[%d]: addr: 0x%lx, len: 0x%lx, type: %d", i,
 			efi_mmap_desc[i].phys_addr, efi_mmap_desc[i].num_pages * PAGE_SIZE, efi_mmap_desc[i].type);
 	}
 
@@ -279,19 +279,19 @@ static uint64_t create_zero_page(struct acrn_vm *vm, uint64_t load_params_gpa)
 		struct acrn_boot_info *abi = get_acrn_boot_info();
 
 		if (boot_from_uefi(abi)) {
-			struct efi_info *sos_efi_info = &zeropage->boot_efi_info;
+			struct efi_info *service_vm_efi_info = &zeropage->boot_efi_info;
 			uint64_t efi_mmap_gpa = BZIMG_EFIMMAP_GPA(load_params_gpa);
 			struct efi_memory_desc *efi_mmap_desc = (struct efi_memory_desc *)gpa2hva(vm, efi_mmap_gpa);
-			uint16_t efi_mmap_desc_nr = create_sos_vm_efi_mmap_desc(vm, efi_mmap_desc);
+			uint16_t efi_mmap_desc_nr = create_service_vm_efi_mmap_desc(vm, efi_mmap_desc);
 
-			sos_efi_info->loader_signature = 0x34364c45; /* "EL64" */
-			sos_efi_info->memdesc_version = abi->uefi_info.memdesc_version;
-			sos_efi_info->memdesc_size = sizeof(struct efi_memory_desc);
-			sos_efi_info->memmap_size = efi_mmap_desc_nr * sizeof(struct efi_memory_desc);
-			sos_efi_info->memmap = (uint32_t)efi_mmap_gpa;
-			sos_efi_info->memmap_hi = (uint32_t)(efi_mmap_gpa >> 32U);
-			sos_efi_info->systab = abi->uefi_info.systab;
-			sos_efi_info->systab_hi = abi->uefi_info.systab_hi;
+			service_vm_efi_info->loader_signature = 0x34364c45; /* "EL64" */
+			service_vm_efi_info->memdesc_version = abi->uefi_info.memdesc_version;
+			service_vm_efi_info->memdesc_size = sizeof(struct efi_memory_desc);
+			service_vm_efi_info->memmap_size = efi_mmap_desc_nr * sizeof(struct efi_memory_desc);
+			service_vm_efi_info->memmap = (uint32_t)efi_mmap_gpa;
+			service_vm_efi_info->memmap_hi = (uint32_t)(efi_mmap_gpa >> 32U);
+			service_vm_efi_info->systab = abi->uefi_info.systab;
+			service_vm_efi_info->systab_hi = abi->uefi_info.systab_hi;
 		}
 	}
 #endif
diff --git a/hypervisor/boot/guest/vboot_info.c b/hypervisor/boot/guest/vboot_info.c
index 79ba5e0a9..a51501f0d 100644
--- a/hypervisor/boot/guest/vboot_info.c
+++ b/hypervisor/boot/guest/vboot_info.c
@@ -71,7 +71,7 @@ static int32_t init_vm_kernel_info(struct acrn_vm *vm, const struct abi_module *
 	return ret;
 }
 
-/* cmdline parsed from abi module string, for pre-launched VMs and SOS VM only. */
+/* cmdline parsed from abi module string, for pre-launched VMs and Service VM only. */
 static char mod_cmdline[PRE_VM_NUM + SOS_VM_NUM][MAX_BOOTARGS_SIZE] = { '\0' };
 
 /**
@@ -94,26 +94,26 @@ static void init_vm_bootargs_info(struct acrn_vm *vm, const struct acrn_boot_inf
 			char seed_args[MAX_SEED_ARG_SIZE] = "";
 
 			fill_seed_arg(seed_args, MAX_SEED_ARG_SIZE);
-			/* Fill seed argument for SOS
+			/* Fill seed argument for Service VM
 			 * seed_args string ends with a white space and '\0', so no additional delimiter is needed
 			 */
 			if (strncat_s((char *)vm->sw.bootargs_info.src_addr, MAX_BOOTARGS_SIZE,
 					seed_args, (MAX_BOOTARGS_SIZE - 1U)) != 0) {
-				pr_err("failed to fill seed arg to SOS bootargs!");
+				pr_err("failed to fill seed arg to Service VM bootargs!");
 			}
 
-			/* If there is cmdline from abi->cmdline, merge it with configured SOS bootargs.
+			/* If there is cmdline from abi->cmdline, merge it with configured Service VM bootargs.
 			 * This is very helpful when one of configured bootargs need to be revised at GRUB runtime
 			 * (e.g. "root="), since the later one would override the previous one if multiple bootargs exist.
 			 */
 			if (abi->cmdline[0] != '\0') {
 				if (strncat_s((char *)vm->sw.bootargs_info.src_addr, MAX_BOOTARGS_SIZE,
 						abi->cmdline, (MAX_BOOTARGS_SIZE - 1U)) != 0) {
-					pr_err("failed to merge mbi cmdline to SOS bootargs!");
+					pr_err("failed to merge mbi cmdline to Service VM bootargs!");
 				}
 			}
 		} else {
-			pr_err("no space to append SOS bootargs!");
+			pr_err("no space to append Service VM bootargs!");
 		}
 
 	}
diff --git a/hypervisor/boot/include/boot.h b/hypervisor/boot/include/boot.h
index 259ae7660..f66ac7ff3 100644
--- a/hypervisor/boot/include/boot.h
+++ b/hypervisor/boot/include/boot.h
@@ -19,7 +19,7 @@
 #define MAX_PROTOCOL_NAME_SIZE		16U
 #define MAX_MOD_STRING_SIZE		2048U
 
-/* The modules in multiboot are: Pre-launched VM: kernel/ramdisk/acpi; SOS VM: kernel/ramdisk */
+/* The modules in multiboot are: Pre-launched VM: kernel/ramdisk/acpi; Service VM: kernel/ramdisk */
 #define MAX_MODULE_NUM			(3U * PRE_VM_NUM + 2U * SOS_VM_NUM)
 
 /* The vACPI module size is fixed to 1MB */
diff --git a/hypervisor/common/hypercall.c b/hypervisor/common/hypercall.c
index 6d6898c7d..287b9f5a1 100644
--- a/hypervisor/common/hypercall.c
+++ b/hypervisor/common/hypercall.c
@@ -75,9 +75,9 @@ inline static bool is_severity_pass(uint16_t target_vmid)
 }
 
 /**
- * @brief offline vcpu from SOS
+ * @brief offline vcpu from Service VM
  *
- * The function offline specific vcpu from SOS.
+ * The function offline specific vcpu from Service VM.
  *
  * @param vcpu Pointer to vCPU that initiates the hypercall
  * @param param1 lapic id of the vcpu which wants to offline
@@ -85,7 +85,7 @@ inline static bool is_severity_pass(uint16_t target_vmid)
  * @pre is_service_vm(vcpu->vm)
  * @return 0 on success, non-zero on error.
  */
-int32_t hcall_sos_offline_cpu(struct acrn_vcpu *vcpu, __unused struct acrn_vm *target_vm,
+int32_t hcall_service_vm_offline_cpu(struct acrn_vcpu *vcpu, __unused struct acrn_vm *target_vm,
 		uint64_t param1, __unused uint64_t param2)
 {
 	struct acrn_vcpu *target_vcpu;
@@ -93,7 +93,7 @@ int32_t hcall_sos_offline_cpu(struct acrn_vcpu *vcpu, __unused struct acrn_vm *t
 	int32_t ret = 0;
 	uint64_t lapicid = param1;
 
-	pr_info("sos offline cpu with lapicid %ld", lapicid);
+	pr_info("Service VM offline cpu with lapicid %ld", lapicid);
 
 	foreach_vcpu(i, vcpu->vm, target_vcpu) {
 		if (vlapic_get_apicid(vcpu_vlapic(target_vcpu)) == lapicid) {
@@ -113,7 +113,7 @@ int32_t hcall_sos_offline_cpu(struct acrn_vcpu *vcpu, __unused struct acrn_vm *t
 /**
  * @brief Get hypervisor api version
  *
- * The function only return api version information when VM is SOS_VM.
+ * The function only return api version information when VM is Service VM.
  *
  * @param vcpu Pointer to vCPU that initiates the hypercall
  * @param param1 guest physical memory address. The api version returned
@@ -283,7 +283,7 @@ int32_t hcall_create_vm(struct acrn_vcpu *vcpu, struct acrn_vm *target_vm, uint6
 					pr_err("Wrong guest flags 0x%lx\n", vm_config->guest_flags);
 				} else {
 					if (create_vm(vmid, pcpu_bitmap, vm_config, &tgt_vm) == 0) {
-						/* return a relative vm_id from SOS view */
+						/* return a relative vm_id from Service VM view */
 						cv.vmid = vmid_2_rel_vmid(vm->vm_id, vmid);
 						cv.vcpu_num = tgt_vm->hw.created_vcpus;
 					} else {
@@ -606,13 +606,13 @@ int32_t hcall_notify_ioreq_finish(__unused struct acrn_vcpu *vcpu, struct acrn_v
 
 /**
  *@pre is_service_vm(vm)
- *@pre gpa2hpa(vm, region->sos_vm_gpa) != INVALID_HPA
+ *@pre gpa2hpa(vm, region->service_vm_gpa) != INVALID_HPA
  */
 static void add_vm_memory_region(struct acrn_vm *vm, struct acrn_vm *target_vm,
 				const struct vm_memory_region *region,uint64_t *pml4_page)
 {
 	uint64_t prot = 0UL, base_paddr;
-	uint64_t hpa = gpa2hpa(vm, region->sos_vm_gpa);
+	uint64_t hpa = gpa2hpa(vm, region->service_vm_gpa);
 
 	/* access right */
 	if ((region->prot & MEM_ACCESS_READ) != 0U) {
@@ -641,7 +641,7 @@ static void add_vm_memory_region(struct acrn_vm *vm, struct acrn_vm *target_vm,
 	/* If Software SRAM is initialized, and HV received a request to map Software SRAM
 	 * area to guest, we should add EPT_WB flag to make Software SRAM effective.
 	 * TODO: We can enforce WB for any region has overlap with Software SRAM, for simplicity,
-	 * and leave it to SOS to make sure it won't violate.
+	 * and leave it to Service VM to make sure it won't violate.
 	 */
 	if (is_software_sram_enabled()) {
 		base_paddr = get_software_sram_base();
@@ -667,8 +667,8 @@ static int32_t set_vm_memory_region(struct acrn_vm *vm,
 	if ((region->size & (PAGE_SIZE - 1UL)) == 0UL) {
 		pml4_page = (uint64_t *)target_vm->arch_vm.nworld_eptp;
 		if (region->type == MR_ADD) {
-			/* if the GPA range is SOS valid GPA or not */
-			if (ept_is_valid_mr(vm, region->sos_vm_gpa, region->size)) {
+			/* if the GPA range is Service VM valid GPA or not */
+			if (ept_is_valid_mr(vm, region->service_vm_gpa, region->size)) {
 				/* FIXME: how to filter the alias mapping ? */
 				add_vm_memory_region(vm, target_vm, region, pml4_page);
 				ret = 0;
@@ -682,9 +682,9 @@ static int32_t set_vm_memory_region(struct acrn_vm *vm,
 	}
 
 	dev_dbg((ret == 0) ? DBG_LEVEL_HYCALL : LOG_ERROR,
-			"[vm%d] type=%d gpa=0x%x sos_gpa=0x%x sz=0x%x",
+			"[vm%d] type=%d gpa=0x%x service_vm_gpa=0x%x sz=0x%x",
 			target_vm->vm_id, region->type, region->gpa,
-			region->sos_vm_gpa, region->size);
+			region->service_vm_gpa, region->size);
 	return ret;
 }
 
@@ -1210,7 +1210,7 @@ int32_t hcall_vm_intr_monitor(struct acrn_vcpu *vcpu, struct acrn_vm *target_vm,
  *
  * This is the API that helps to switch the notifer vecotr. If this API is
  * not called, the hypervisor will use the default notifier vector(0xF3)
- * to notify the SOS kernel.
+ * to notify the Service VM kernel.
  *
  * @param vcpu Pointer to vCPU that initiates the hypercall
  * @param param1 the expected notifier vector from guest
diff --git a/hypervisor/debug/logmsg.c b/hypervisor/debug/logmsg.c
index 0eb8f75f3..9b652659c 100644
--- a/hypervisor/debug/logmsg.c
+++ b/hypervisor/debug/logmsg.c
@@ -14,7 +14,7 @@
 #include <ticks.h>
 
 /* buf size should be identical to the size in hvlog option, which is
- * transfered to SOS:
+ * transfered to Service VM:
  * bsp/uefi/clearlinux/acrn.conf: hvlog=2M@0x1FE00000
  */
 
diff --git a/hypervisor/debug/profiling.c b/hypervisor/debug/profiling.c
index 1929aa7ad..ff52aa0b3 100644
--- a/hypervisor/debug/profiling.c
+++ b/hypervisor/debug/profiling.c
@@ -298,7 +298,7 @@ static int32_t profiling_sbuf_put_variable(struct shared_buf *sbuf,
 }
 
 /*
- * Read profiling data and transferred to SOS
+ * Read profiling data and transferred to Service VM
  * Drop transfer of profiling data if sbuf is full/insufficient and log it
  */
 static int32_t profiling_generate_data(int32_t collector, uint32_t type)
@@ -1394,7 +1394,7 @@ void profiling_setup(void)
 
 	dev_dbg(DBG_LEVEL_PROFILING, "%s: entering", __func__);
 	cpu = get_pcpu_id();
-	/* support PMI notification, SOS_VM will register all CPU */
+	/* support PMI notification, Service VM will register all CPU */
 	if ((cpu == BSP_CPU_ID) && (profiling_pmi_irq == IRQ_INVALID)) {
 		pr_info("%s: calling request_irq", __func__);
 		retval = request_irq(PMI_IRQ,
diff --git a/hypervisor/debug/shell.c b/hypervisor/debug/shell.c
index b6cf83133..863a4321c 100644
--- a/hypervisor/debug/shell.c
+++ b/hypervisor/debug/shell.c
@@ -977,7 +977,7 @@ static int32_t shell_to_vm_console(int32_t argc, char **argv)
 		return 0;
 	}
 	console_vmid = vm_id;
-	/* Output that switching to SOS shell */
+	/* Output that switching to Service VM shell */
 	snprintf(temp_str, TEMP_STR_SIZE, "\r\n----- Entering VM %d Shell -----\r\n", vm_id);
 
 	shell_puts(temp_str);
diff --git a/hypervisor/dm/io_req.c b/hypervisor/dm/io_req.c
index cb1224105..b68a66cab 100644
--- a/hypervisor/dm/io_req.c
+++ b/hypervisor/dm/io_req.c
@@ -70,7 +70,7 @@ static inline bool has_complete_ioreq(const struct acrn_vcpu *vcpu)
 }
 
 /**
- * @brief Deliver \p io_req to SOS and suspend \p vcpu till its completion
+ * @brief Deliver \p io_req to Service VM and suspend \p vcpu till its completion
  *
  * @param vcpu The virtual CPU that triggers the MMIO access
  * @param io_req The I/O request holding the details of the MMIO access
@@ -168,7 +168,7 @@ void set_io_req_state(struct acrn_vm *vm, uint16_t vcpu_id, uint32_t state)
 		acrn_io_req = &req_buf->req_slot[vcpu_id];
 		/*
 		 * HV will only set processed to ACRN_IOREQ_STATE_PENDING or ACRN_IOREQ_STATE_FREE.
-		 * we don't need to sfence here is that even if the SOS/DM sees the previous state,
+		 * we don't need to sfence here is that even if the Service-VM/DM sees the previous state,
 		 * the only side effect is that it will defer the processing of the new IOReq.
 		 * It won't lead wrong processing.
 		 */
diff --git a/hypervisor/dm/vioapic.c b/hypervisor/dm/vioapic.c
index 748e2000f..641674c16 100644
--- a/hypervisor/dm/vioapic.c
+++ b/hypervisor/dm/vioapic.c
@@ -122,7 +122,7 @@ vgsi_to_vioapic_and_vpin(const struct acrn_vm *vm, uint32_t vgsi, uint32_t *vpin
 
 	if (is_service_vm(vm)) {
 		/*
-		 * Utilize platform ioapic_info for SOS VM
+		 * Utilize platform ioapic_info for Service VM
 		 */	
 		vioapic_index = get_gsi_to_ioapic_index(vgsi);
 		if (vpin != NULL) {
diff --git a/hypervisor/dm/vpci/pci_pt.c b/hypervisor/dm/vpci/pci_pt.c
index c34e5adbf..e899061b0 100644
--- a/hypervisor/dm/vpci/pci_pt.c
+++ b/hypervisor/dm/vpci/pci_pt.c
@@ -258,7 +258,7 @@ static void vdev_pt_allow_io_vbar(struct pci_vdev *vdev, uint32_t idx)
 {
 	struct acrn_vm *vm = vpci2vm(vdev->vpci);
 
-	/* For SOS, all port IO access is allowed by default, so skip SOS here */
+	/* For Service VM, all port IO access is allowed by default, so skip Service VM here */
 	if (!is_service_vm(vm)) {
 		struct pci_vbar *vbar = &vdev->vbars[idx];
 		if (vbar->base_gpa != 0UL) {
@@ -276,7 +276,7 @@ static void vdev_pt_deny_io_vbar(struct pci_vdev *vdev, uint32_t idx)
 {
 	struct acrn_vm *vm = vpci2vm(vdev->vpci);
 
-	/* For SOS, all port IO access is allowed by default, so skip SOS here */
+	/* For Service VM, all port IO access is allowed by default, so skip Service VM here */
 	if (!is_service_vm(vm)) {
 		struct pci_vbar *vbar = &vdev->vbars[idx];
 		if (vbar->base_gpa != 0UL) {
@@ -556,7 +556,7 @@ void init_vdev_pt(struct pci_vdev *vdev, bool is_pf_vdev)
 		}
 	} else {
 		if (vdev->phyfun->vpci != vdev->vpci) {
-			/* VF is assigned to a UOS */
+			/* VF is assigned to a User VM */
 			uint32_t vid, did;
 
 			vdev->nr_bars = PCI_BAR_COUNT;
diff --git a/hypervisor/dm/vpci/vdev.c b/hypervisor/dm/vpci/vdev.c
index df55c67ba..0d2b448e4 100644
--- a/hypervisor/dm/vpci/vdev.c
+++ b/hypervisor/dm/vpci/vdev.c
@@ -155,7 +155,7 @@ static void pci_vdev_update_vbar_base(struct pci_vdev *vdev, uint32_t idx)
 					|| (!mem_aligned_check(base, vdev->vbars[idx].size))) {
 			res = (base < (1UL << 32UL)) ? &(vdev->vpci->res32): &(vdev->vpci->res64);
 			/* VM tries to reprogram vbar address out of pci mmio bar window, it can be caused by:
-			 * 1. For SOS, <board>.xml is misaligned with the actual native platform, and we get wrong mmio window.
+			 * 1. For Service VM, <board>.xml is misaligned with the actual native platform, and we get wrong mmio window.
 			 * 2. Malicious operation from VM, it tries to reprogram vbar address out of pci mmio bar window
 			 */
 			pr_err("%s reprogram PCI:%02x:%02x.%x BAR%d to addr:0x%lx,"
diff --git a/hypervisor/dm/vpci/vhostbridge.c b/hypervisor/dm/vpci/vhostbridge.c
index 642b64bfd..861e0e222 100644
--- a/hypervisor/dm/vpci/vhostbridge.c
+++ b/hypervisor/dm/vpci/vhostbridge.c
@@ -118,7 +118,7 @@ static void init_vhostbridge(struct pci_vdev *vdev)
 		 */
 		pciexbar_low = UOS_VIRT_PCI_MMCFG_BASE | 0x1U;
 	} else {
-		/*Inject physical ECAM value to SOS vhostbridge since SOS may check PCIe-MMIO Base Address with it */
+		/*Inject physical ECAM value to Service VM vhostbridge since Service VM may check PCIe-MMIO Base Address with it */
 		phys_did = pci_pdev_read_cfg(hostbridge_bdf, PCIR_DEVICE, 2);
 		for (i = 0U; i < (sizeof(hostbridge_did_highbytes) / sizeof(uint32_t)); i++) {
 			if (((phys_did & 0xff00U) >> 8) == hostbridge_did_highbytes[i]) {
diff --git a/hypervisor/dm/vpci/vpci.c b/hypervisor/dm/vpci/vpci.c
index 92dc8f8b0..802e1f32b 100644
--- a/hypervisor/dm/vpci/vpci.c
+++ b/hypervisor/dm/vpci/vpci.c
@@ -107,7 +107,7 @@ static bool vpci_pio_cfgaddr_write(struct acrn_vcpu *vcpu, uint16_t addr, size_t
  * @pre vcpu->vm != NULL
  * @pre vcpu->vm->vm_id < CONFIG_MAX_VM_NUM
  * @pre (get_vm_config(vcpu->vm->vm_id)->load_order == PRE_LAUNCHED_VM)
- *	|| (get_vm_config(vcpu->vm->vm_id)->load_order == SOS_VM)
+ *	|| (get_vm_config(vcpu->vm->vm_id)->load_order == SERVICE_VM)
  *
  * @retval true on success.
  * @retval false. (ACRN will deliver this IO request to DM to handle for post-launched VM)
@@ -224,7 +224,7 @@ int32_t init_vpci(struct acrn_vm *vm)
 	vm->iommu = create_iommu_domain(vm->vm_id, hva2hpa(vm->arch_vm.nworld_eptp), 48U);
 
 	vm_config = get_vm_config(vm->vm_id);
-	/* virtual PCI MMCONFIG for SOS is same with the physical value */
+	/* virtual PCI MMCONFIG for Service VM is same with the physical value */
 	if (vm_config->load_order == SOS_VM) {
 		pci_mmcfg = get_mmcfg_region();
 		vm->vpci.pci_mmcfg = *pci_mmcfg;
@@ -341,7 +341,7 @@ static void remove_vdev_pt_iommu_domain(const struct pci_vdev *vdev)
  * @brief Find an available vdev structure with BDF from a specified vpci structure.
  *        If the vdev's vpci is the same as the specified vpci, the vdev is available.
  *        If the vdev's vpci is not the same as the specified vpci, the vdev has already
- *        been assigned and it is unavailable for SOS.
+ *        been assigned and it is unavailable for Service VM.
  *        If the vdev's vpci is NULL, the vdev is a orphan/zombie instance, it can't
  *        be accessed by any vpci.
  *
@@ -358,7 +358,7 @@ static struct pci_vdev *find_available_vdev(struct acrn_vpci *vpci, union pci_bd
 
 	if ((vdev != NULL) && (vdev->user != vdev)) {
 		if (vdev->user != NULL) {
-			/* the SOS is able to access, if and only if the SOS has higher severity than the UOS. */
+			/* the Service VM is able to access, if and only if the Service VM has higher severity than the UOS. */
 			if (get_vm_severity(vpci2vm(vpci)->vm_id) <
 					get_vm_severity(vpci2vm(vdev->user->vpci)->vm_id)) {
 				vdev = NULL;
@@ -693,7 +693,7 @@ static int32_t vpci_init_vdevs(struct acrn_vm *vm)
 }
 
 /**
- * @brief assign a PCI device from SOS to target post-launched VM.
+ * @brief assign a PCI device from Service VM to target post-launched VM.
  *
  * @pre tgt_vm != NULL
  * @pre pcidev != NULL
@@ -702,41 +702,41 @@ int32_t vpci_assign_pcidev(struct acrn_vm *tgt_vm, struct acrn_pcidev *pcidev)
 {
 	int32_t ret = 0;
 	uint32_t idx;
-	struct pci_vdev *vdev_in_sos, *vdev;
+	struct pci_vdev *vdev_in_service_vm, *vdev;
 	struct acrn_vpci *vpci;
 	union pci_bdf bdf;
-	struct acrn_vm *sos_vm;
+	struct acrn_vm *service_vm;
 
 	bdf.value = pcidev->phys_bdf;
-	sos_vm = get_sos_vm();
-	spinlock_obtain(&sos_vm->vpci.lock);
-	vdev_in_sos = pci_find_vdev(&sos_vm->vpci, bdf);
-	if ((vdev_in_sos != NULL) && (vdev_in_sos->user == vdev_in_sos) &&
-			(vdev_in_sos->pdev != NULL) &&
-			!is_host_bridge(vdev_in_sos->pdev) && !is_bridge(vdev_in_sos->pdev)) {
+	service_vm = get_service_vm();
+	spinlock_obtain(&service_vm->vpci.lock);
+	vdev_in_service_vm = pci_find_vdev(&service_vm->vpci, bdf);
+	if ((vdev_in_service_vm != NULL) && (vdev_in_service_vm->user == vdev_in_service_vm) &&
+			(vdev_in_service_vm->pdev != NULL) &&
+			!is_host_bridge(vdev_in_service_vm->pdev) && !is_bridge(vdev_in_service_vm->pdev)) {
 
 		/* ToDo: Each PT device must support one type reset */
-		if (!vdev_in_sos->pdev->has_pm_reset && !vdev_in_sos->pdev->has_flr &&
-				!vdev_in_sos->pdev->has_af_flr) {
+		if (!vdev_in_service_vm->pdev->has_pm_reset && !vdev_in_service_vm->pdev->has_flr &&
+				!vdev_in_service_vm->pdev->has_af_flr) {
 			pr_fatal("%s %x:%x.%x not support FLR or not support PM reset\n",
 				__func__, bdf.bits.b,  bdf.bits.d,  bdf.bits.f);
 		} else {
 			/* DM will reset this device before assigning it */
-			pdev_restore_bar(vdev_in_sos->pdev);
+			pdev_restore_bar(vdev_in_service_vm->pdev);
 		}
 
-		vdev_in_sos->vdev_ops->deinit_vdev(vdev_in_sos);
+		vdev_in_service_vm->vdev_ops->deinit_vdev(vdev_in_service_vm);
 
 		vpci = &(tgt_vm->vpci);
 
 		spinlock_obtain(&tgt_vm->vpci.lock);
-		vdev = vpci_init_vdev(vpci, vdev_in_sos->pci_dev_config, vdev_in_sos->phyfun);
+		vdev = vpci_init_vdev(vpci, vdev_in_service_vm->pci_dev_config, vdev_in_service_vm->phyfun);
 		pci_vdev_write_vcfg(vdev, PCIR_INTERRUPT_LINE, 1U, pcidev->intr_line);
 		pci_vdev_write_vcfg(vdev, PCIR_INTERRUPT_PIN, 1U, pcidev->intr_pin);
 		for (idx = 0U; idx < vdev->nr_bars; idx++) {
 			/* VF is assigned to a UOS */
 			if (vdev->phyfun != NULL) {
-				vdev->vbars[idx] = vdev_in_sos->vbars[idx];
+				vdev->vbars[idx] = vdev_in_service_vm->vbars[idx];
 				if (has_msix_cap(vdev) && (idx == vdev->msix.table_bar)) {
 					vdev->msix.mmio_hpa = vdev->vbars[idx].base_hpa;
 					vdev->msix.mmio_size = vdev->vbars[idx].size;
@@ -753,11 +753,11 @@ int32_t vpci_assign_pcidev(struct acrn_vm *tgt_vm, struct acrn_pcidev *pcidev)
 			/*We should re-add the vdev to hashlist since its vbdf has changed */
 			hlist_del(&vdev->link);
 			hlist_add_head(&vdev->link, &vpci->vdevs_hlist_heads[hash64(vdev->bdf.value, VDEV_LIST_HASHBITS)]);
-			vdev->parent_user = vdev_in_sos;
-			vdev_in_sos->user = vdev;
+			vdev->parent_user = vdev_in_service_vm;
+			vdev_in_service_vm->user = vdev;
 		} else {
 			vdev->vdev_ops->deinit_vdev(vdev);
-			vdev_in_sos->vdev_ops->init_vdev(vdev_in_sos);
+			vdev_in_service_vm->vdev_ops->init_vdev(vdev_in_service_vm);
 		}
 		spinlock_release(&tgt_vm->vpci.lock);
 	} else {
@@ -767,13 +767,13 @@ int32_t vpci_assign_pcidev(struct acrn_vm *tgt_vm, struct acrn_pcidev *pcidev)
 			pcidev->virt_bdf >> 8U, (pcidev->virt_bdf >> 3U) & 0x1fU, pcidev->virt_bdf & 0x7U);
 		ret = -ENODEV;
 	}
-	spinlock_release(&sos_vm->vpci.lock);
+	spinlock_release(&service_vm->vpci.lock);
 
 	return ret;
 }
 
 /**
- * @brief deassign a PCI device from target post-launched VM to SOS.
+ * @brief deassign a PCI device from target post-launched VM to Service VM.
  *
  * @pre tgt_vm != NULL
  * @pre pcidev != NULL
diff --git a/hypervisor/dm/vpci/vpci_bridge.c b/hypervisor/dm/vpci/vpci_bridge.c
index 7f5a8473a..0f824726b 100644
--- a/hypervisor/dm/vpci/vpci_bridge.c
+++ b/hypervisor/dm/vpci/vpci_bridge.c
@@ -42,7 +42,7 @@
  *  1. configure tool can select whether a PCI bridge is emulated or pass through
  *
  * Open:
- *   1. SOS how to reset PCI devices under the PCI bridge
+ *   1. Service VM how to reset PCI devices under the PCI bridge
  */
 
 #include <asm/guest/vm.h>
diff --git a/hypervisor/dm/vpci/vsriov.c b/hypervisor/dm/vpci/vsriov.c
index fb4c46dd3..f4c0bf191 100644
--- a/hypervisor/dm/vpci/vsriov.c
+++ b/hypervisor/dm/vpci/vsriov.c
@@ -216,7 +216,7 @@ static void enable_vfs(struct pci_vdev *pf_vdev)
 	} else {
 		/*
 		 * If the VF physical device was not created successfully, the pdev/vdev
-		 * will also not be created so that SOS can aware of VF creation failure,
+		 * will also not be created so that Service VM can aware of VF creation failure,
 		 */
 		pr_err("PF %x:%x.%x can't create VFs after 100 ms",
 			pf_vdev->bdf.bits.b, pf_vdev->bdf.bits.d, pf_vdev->bdf.bits.f);
@@ -238,7 +238,7 @@ static void disable_vfs(struct pci_vdev *pf_vdev)
 	 * we simply set the VF instance status to "zombie" to avoid dynamically adding/removing
 	 * resources
 	 *
-	 * If the VF drivers are still running in SOS or UOS, the MMIO access will return 0xFF.
+	 * If the VF drivers are still running in Service VM or User VM, the MMIO access will return 0xFF.
 	 */
 	num_vfs = read_sriov_reg(pf_vdev, PCIR_SRIOV_NUMVFS);
 	first = read_sriov_reg(pf_vdev, PCIR_SRIOV_FST_VF_OFF);
diff --git a/hypervisor/dm/vpic.c b/hypervisor/dm/vpic.c
index 29b40531b..775b1c9c6 100644
--- a/hypervisor/dm/vpic.c
+++ b/hypervisor/dm/vpic.c
@@ -327,7 +327,7 @@ static uint32_t vpin_to_vgsi(const struct acrn_vm *vm, uint32_t vpin)
 
 	if (is_service_vm(vm)) {
 		/*
-		 * For SOS VM vPIC pin to GSI is same as the one
+		 * For Service VM vPIC pin to GSI is same as the one
 		 * that is used for platform
 		 */
 		vgsi = get_pic_pin_from_ioapic_pin(vpin);
@@ -363,7 +363,7 @@ static uint32_t vgsi_to_vpin(const struct acrn_vm *vm, uint32_t vgsi)
 
 	if (is_service_vm(vm)) {
 		/*
-		 * For SOS VM vPIC pin to GSI is same as the one
+		 * For Service VM vPIC pin to GSI is same as the one
 		 * that is used for platform
 		 */
 		vpin = get_pic_pin_from_ioapic_pin(vgsi);
diff --git a/hypervisor/hw/pci.c b/hypervisor/hw/pci.c
index 4b6205e61..943c5cef3 100644
--- a/hypervisor/hw/pci.c
+++ b/hypervisor/hw/pci.c
@@ -558,7 +558,7 @@ static void pci_parse_iommu_devscopes(struct pci_bdf_mapping_group *const bdfs_f
 }
 
 /*
- * There are some rules to config PCI bridge: try to avoid interference between SOS and RTVM or
+ * There are some rules to config PCI bridge: try to avoid interference between Service VM and RTVM or
  * pre-launched VM; and to support some features like SRIOV by default, so as following:
  *	1. disable interrupt, including INTx and MSI.
  *	2. enable ARI if it's a PCIe bridge and all its sub devices support ARI (need check further).
@@ -600,7 +600,7 @@ static void	config_pci_bridge(const struct pci_pdev *pdev)
 /*
  * @brief: walks through all pdevs that have been initialized and determine
  * which pdevs need to be added to pci dev_config. The pdevs added to pci
- * dev_config will be exposed to SOS finally.
+ * dev_config will be exposed to Service VM finally.
  */
 static void init_all_dev_config(void)
 {
diff --git a/hypervisor/include/arch/x86/asm/guest/assign.h b/hypervisor/include/arch/x86/asm/guest/assign.h
index b054152d5..8095aecdd 100644
--- a/hypervisor/include/arch/x86/asm/guest/assign.h
+++ b/hypervisor/include/arch/x86/asm/guest/assign.h
@@ -55,8 +55,8 @@ void ptirq_intx_ack(struct acrn_vm *vm, uint32_t virt_gsi, enum intx_ctlr vgsi_c
  * @return
  *    - 0: on success
  *    - \p -ENODEV:
- *      - for SOS, the entry already be held by others
- *      - for UOS, no pre-hold mapping found.
+ *      - for Service VM, the entry already be held by others
+ *      - for User VM, no pre-hold mapping found.
  *
  * @pre vm != NULL
  * @pre info != NULL
@@ -79,8 +79,8 @@ int32_t ptirq_prepare_msix_remap(struct acrn_vm *vm, uint16_t virt_bdf,  uint16_
  * @return
  *    - 0: on success
  *    - \p -ENODEV:
- *      - for SOS, the entry already be held by others
- *      - for UOS, no pre-hold mapping found.
+ *      - for Service VM, the entry already be held by others
+ *      - for User VM, no pre-hold mapping found.
  *
  * @pre vm != NULL
  *
@@ -90,7 +90,7 @@ int32_t ptirq_intx_pin_remap(struct acrn_vm *vm, uint32_t virt_gsi, enum intx_ct
 /**
  * @brief Add an interrupt remapping entry for INTx as pre-hold mapping.
  *
- * Except sos_vm, Device Model should call this function to pre-hold ptdev intx
+ * Except Service VM, Device Model should call this function to pre-hold ptdev intx
  * The entry is identified by phys_pin, one entry vs. one phys_pin.
  * Currently, one phys_pin can only be held by one pin source (vPIC or vIOAPIC).
  *
diff --git a/hypervisor/include/arch/x86/asm/guest/ept.h b/hypervisor/include/arch/x86/asm/guest/ept.h
index b01bcef4f..1d2b37c19 100644
--- a/hypervisor/include/arch/x86/asm/guest/ept.h
+++ b/hypervisor/include/arch/x86/asm/guest/ept.h
@@ -64,13 +64,13 @@ uint64_t gpa2hpa(struct acrn_vm *vm, uint64_t gpa);
  */
 uint64_t local_gpa2hpa(struct acrn_vm *vm, uint64_t gpa, uint32_t *size);
 /**
- * @brief Translating from host-physical address to guest-physical address for SOS_VM
+ * @brief Translating from host-physical address to guest-physical address for Service VM
  *
  * @param[in] hpa the specified host-physical address
  *
- * @pre: the gpa and hpa are identical mapping in SOS.
+ * @pre: the gpa and hpa are identical mapping in Service VM.
  */
-uint64_t sos_vm_hpa2gpa(uint64_t hpa);
+uint64_t service_vm_hpa2gpa(uint64_t hpa);
 /**
  * @brief Guest-physical memory region mapping
  *
diff --git a/hypervisor/include/arch/x86/asm/guest/vm.h b/hypervisor/include/arch/x86/asm/guest/vm.h
index a762dbf5e..023abcaca 100644
--- a/hypervisor/include/arch/x86/asm/guest/vm.h
+++ b/hypervisor/include/arch/x86/asm/guest/vm.h
@@ -215,13 +215,13 @@ static inline struct acrn_vcpu *vcpu_from_pid(struct acrn_vm *vm, uint16_t pcpu_
 }
 
 /* Convert relative vm id to absolute vm id */
-static inline uint16_t rel_vmid_2_vmid(uint16_t sos_vmid, uint16_t rel_vmid) {
-	return (sos_vmid + rel_vmid);
+static inline uint16_t rel_vmid_2_vmid(uint16_t service_vmid, uint16_t rel_vmid) {
+	return (service_vmid + rel_vmid);
 }
 
 /* Convert absolute vm id to relative vm id */
-static inline uint16_t vmid_2_rel_vmid(uint16_t sos_vmid, uint16_t vmid) {
-	return (vmid - sos_vmid);
+static inline uint16_t vmid_2_rel_vmid(uint16_t service_vmid, uint16_t vmid) {
+	return (vmid - service_vmid);
 }
 
 void make_shutdown_vm_request(uint16_t pcpu_id);
@@ -243,9 +243,9 @@ bool is_postlaunched_vm(const struct acrn_vm *vm);
 bool is_prelaunched_vm(const struct acrn_vm *vm);
 uint16_t get_vmid_by_uuid(const uint8_t *uuid);
 struct acrn_vm *get_vm_from_vmid(uint16_t vm_id);
-struct acrn_vm *get_sos_vm(void);
+struct acrn_vm *get_service_vm(void);
 
-void create_sos_vm_e820(struct acrn_vm *vm);
+void create_service_vm_e820(struct acrn_vm *vm);
 void create_prelaunched_vm_e820(struct acrn_vm *vm);
 uint64_t find_space_from_ve820(struct acrn_vm *vm, uint32_t size, uint64_t min_addr, uint64_t max_addr);
 
diff --git a/hypervisor/include/arch/x86/asm/guest/vmx_io.h b/hypervisor/include/arch/x86/asm/guest/vmx_io.h
index de2699edf..05ac19cdd 100644
--- a/hypervisor/include/arch/x86/asm/guest/vmx_io.h
+++ b/hypervisor/include/arch/x86/asm/guest/vmx_io.h
@@ -81,7 +81,7 @@ void   allow_guest_pio_access(struct acrn_vm *vm, uint16_t port_address, uint32_
 void deny_guest_pio_access(struct acrn_vm *vm, uint16_t port_address, uint32_t nbytes);
 
 /**
- * @brief Fire HSM interrupt to SOS
+ * @brief Fire HSM interrupt to Service VM
  *
  * @return None
  */
diff --git a/hypervisor/include/arch/x86/asm/vm_config.h b/hypervisor/include/arch/x86/asm/vm_config.h
index 051c07148..9129329ce 100644
--- a/hypervisor/include/arch/x86/asm/vm_config.h
+++ b/hypervisor/include/arch/x86/asm/vm_config.h
@@ -179,7 +179,7 @@ struct acrn_vm_config {
 
 	/*
 	 * below are variable length members (per build).
-	 * SOS can get the vm_configs[] array through hypercall, but SOS may not
+	 * Service VM can get the vm_configs[] array through hypercall, but Service VM may not
 	 * need to parse these members.
 	 */
 
diff --git a/hypervisor/include/common/hypercall.h b/hypervisor/include/common/hypercall.h
index 1490228d9..7c8d3c8d1 100644
--- a/hypervisor/include/common/hypercall.h
+++ b/hypervisor/include/common/hypercall.h
@@ -35,7 +35,7 @@ bool is_hypercall_from_ring0(void);
  * @pre is_service_vm(vcpu->vm)
  * @return 0 on success, non-zero on error.
  */
-int32_t hcall_sos_offline_cpu(struct acrn_vcpu *vcpu, struct acrn_vm *target_vm, uint64_t param1, uint64_t param2);
+int32_t hcall_service_vm_offline_cpu(struct acrn_vcpu *vcpu, struct acrn_vm *target_vm, uint64_t param1, uint64_t param2);
 
 /**
  * @brief Get hypervisor api version
diff --git a/hypervisor/include/dm/io_req.h b/hypervisor/include/dm/io_req.h
index f7bb39699..112255e47 100644
--- a/hypervisor/include/dm/io_req.h
+++ b/hypervisor/include/dm/io_req.h
@@ -172,7 +172,7 @@ struct mem_io_node {
 /* External Interfaces */
 
 /**
- * @brief Deliver \p io_req to SOS and suspend \p vcpu till its completion
+ * @brief Deliver \p io_req to Service VM and suspend \p vcpu till its completion
  *
  * @param vcpu The virtual CPU that triggers the MMIO access
  * @param io_req The I/O request holding the details of the MMIO access
diff --git a/hypervisor/include/dm/vioapic.h b/hypervisor/include/dm/vioapic.h
index 2a2833289..470991d0c 100644
--- a/hypervisor/include/dm/vioapic.h
+++ b/hypervisor/include/dm/vioapic.h
@@ -44,7 +44,7 @@
 #define	VIOAPIC_BASE	0xFEC00000UL
 #define	VIOAPIC_SIZE	4096UL
 
-#define REDIR_ENTRIES_HW	120U /* SOS align with native ioapic */
+#define REDIR_ENTRIES_HW	120U /* Service VM align with native ioapic */
 #define STATE_BITMAP_SIZE	INT_DIV_ROUNDUP(REDIR_ENTRIES_HW, 64U)
 
 #define IOAPIC_RTE_LOW_INTVEC	((uint32_t)IOAPIC_RTE_INTVEC)
diff --git a/hypervisor/include/dm/vpci.h b/hypervisor/include/dm/vpci.h
index 4797c4025..2f2f72a6c 100644
--- a/hypervisor/include/dm/vpci.h
+++ b/hypervisor/include/dm/vpci.h
@@ -140,12 +140,12 @@ struct pci_vdev {
 	const struct pci_vdev_ops *vdev_ops;
 
 	/*
-	 * vdev in    |   HV       |   pre-VM       |               SOS                   | post-VM
-	 *            |            |                |vdev used by SOS|vdev used by post-VM|
-	 * -----------------------------------------------------------------------------------------------
-	 * parent_user| NULL(HV)   |   NULL(HV)     |   NULL(HV)     |   NULL(HV)         | vdev in SOS
-	 * -----------------------------------------------------------------------------------------------
-	 * user       | vdev in HV | vdev in pre-VM |   vdev in SOS  |   vdev in post-VM  | vdev in post-VM
+	 * vdev in    |   HV       |   pre-VM       |          Service VM                        | post-VM
+	 *            |            |                |vdev used by Service VM|vdev used by post-VM|
+	 * ----------------------------------------------------------------------------------------------------------
+	 * parent_user| NULL(HV)   |   NULL(HV)     |   NULL(HV)            |   NULL(HV)         | vdev in Service VM
+	 * ----------------------------------------------------------------------------------------------------------
+	 * user       | vdev in HV | vdev in pre-VM |   vdev in Service VM  |   vdev in post-VM  | vdev in post-VM
 	 */
 	struct pci_vdev *parent_user;
 	struct pci_vdev *user;	/* NULL means this device is not used or is a zombie VF */
diff --git a/hypervisor/include/public/acrn_common.h b/hypervisor/include/public/acrn_common.h
index f8a8a76db..863f62627 100644
--- a/hypervisor/include/public/acrn_common.h
+++ b/hypervisor/include/public/acrn_common.h
@@ -193,11 +193,11 @@ struct acrn_pci_request {
  *    FREE -> PENDING -> PROCESSING -> COMPLETE -> FREE -> ...
  *
  * When a request is in COMPLETE or FREE state, the request is owned by the
- * hypervisor. SOS (HSM or DM) shall not read or write the internals of the
+ * hypervisor. Service VM (HSM or DM) shall not read or write the internals of the
  * request except the state.
  *
  * When a request is in PENDING or PROCESSING state, the request is owned by
- * SOS. The hypervisor shall not read or write the request other than the state.
+ * Service VM. The hypervisor shall not read or write the request other than the state.
  *
  * Based on the rules above, a typical I/O request lifecycle should looks like
  * the following.
@@ -205,7 +205,7 @@ struct acrn_pci_request {
  * @verbatim embed:rst:leading-asterisk
  *
  * +-----------------------+-------------------------+----------------------+
- * | SOS vCPU 0            | SOS vCPU x              | UOS vCPU y           |
+ * | Service VM vCPU 0     | Service VM vCPU x       | User VM vCPU y       |
  * +=======================+=========================+======================+
  * |                       |                         | Hypervisor:          |
  * |                       |                         |                      |
@@ -215,7 +215,7 @@ struct acrn_pci_request {
  * |                       |                         | - Set state to       |
  * |                       |                         |   PENDING (a)        |
  * |                       |                         | - Fire upcall to     |
- * |                       |                         |   SOS vCPU 0         |
+ * |                       |                         |   Service VM vCPU 0  |
  * |                       |                         |                      |
  * +-----------------------+-------------------------+----------------------+
  * | HSM:                  |                         |                      |
@@ -268,7 +268,7 @@ struct acrn_pci_request {
  *      the hypervisor, as the hypervisor shall not access the request any more.
  *
  *   2. Due to similar reasons, setting state to COMPLETE is the last operation
- *      of request handling in HSM or clients in SOS.
+ *      of request handling in HSM or clients in Service VM.
  */
 struct acrn_io_request {
 	/**
@@ -578,7 +578,7 @@ struct acrn_intr_monitor {
 
 /*
  * PRE_LAUNCHED_VM is launched by ACRN hypervisor, with LAPIC_PT;
- * SOS_VM is launched by ACRN hypervisor, without LAPIC_PT;
+ * Service VM is launched by ACRN hypervisor, without LAPIC_PT;
  * POST_LAUNCHED_VM is launched by ACRN devicemodel, with/without LAPIC_PT depends on usecases.
  *
  * Assumption: vm_configs array is completely initialized w.r.t. load_order member of
@@ -587,7 +587,7 @@ struct acrn_intr_monitor {
 enum acrn_vm_load_order {
 	PRE_LAUNCHED_VM = 0,
 	SOS_VM,
-	POST_LAUNCHED_VM,	/* Launched by Devicemodel in SOS_VM */
+	POST_LAUNCHED_VM,	/* Launched by Devicemodel in Service VM */
 	MAX_LOAD_ORDER
 };
 
diff --git a/hypervisor/include/public/acrn_hv_defs.h b/hypervisor/include/public/acrn_hv_defs.h
index a280e38dd..e7985a694 100644
--- a/hypervisor/include/public/acrn_hv_defs.h
+++ b/hypervisor/include/public/acrn_hv_defs.h
@@ -27,7 +27,7 @@
 /* general */
 #define HC_ID_GEN_BASE               0x0UL
 #define HC_GET_API_VERSION          BASE_HC_ID(HC_ID, HC_ID_GEN_BASE + 0x00UL)
-#define HC_SOS_OFFLINE_CPU          BASE_HC_ID(HC_ID, HC_ID_GEN_BASE + 0x01UL)
+#define HC_SERVICE_VM_OFFLINE_CPU   BASE_HC_ID(HC_ID, HC_ID_GEN_BASE + 0x01UL)
 #define HC_SET_CALLBACK_VECTOR      BASE_HC_ID(HC_ID, HC_ID_GEN_BASE + 0x02UL)
 #define HC_GET_PLATFORM_INFO        BASE_HC_ID(HC_ID, HC_ID_GEN_BASE + 0x03UL)
 
@@ -131,8 +131,8 @@ struct vm_memory_region {
 	/** the beginning guest physical address of the memory reion*/
 	uint64_t gpa;
 
-	/** SOS_VM's guest physcial address which gpa will be mapped to */
-	uint64_t sos_vm_gpa;
+	/** Service VM's guest physcial address which gpa will be mapped to */
+	uint64_t service_vm_gpa;
 
 	/** size of the memory region */
 	uint64_t size;
@@ -337,7 +337,7 @@ struct acrn_platform_info {
 		 */
 		uint64_t vm_configs_addr;
 
-		/** Maximum Kata container number in SOS VM */
+		/** Maximum Kata container number in Service VM */
 		uint64_t max_kata_containers;
 		/** Align the size of Configuration info to 128Bytes. */
 		uint8_t  reserved[104];