diff --git a/hypervisor/arch/x86/pm.c b/hypervisor/arch/x86/pm.c
index 15bae78cc..0cf95a63b 100644
--- a/hypervisor/arch/x86/pm.c
+++ b/hypervisor/arch/x86/pm.c
@@ -14,3 +14,119 @@ void restore_msrs(void)
 	msr_write(MSR_IA32_FS_BASE, (uint64_t)psc);
 #endif
 }
+
+static void acpi_gas_write(struct acpi_generic_address *gas, uint32_t val)
+{
+	if (gas->space_id == SPACE_SYSTEM_MEMORY)
+		mmio_write_word(val, (void *)HPA2HVA(gas->address));
+	else
+		io_write_word(val, gas->address);
+}
+
+static uint32_t acpi_gas_read(struct acpi_generic_address *gas)
+{
+	uint32_t ret = 0;
+
+	if (gas->space_id == SPACE_SYSTEM_MEMORY)
+		ret = mmio_read_word((void *)HPA2HVA(gas->address));
+	else
+		ret = io_read_word(gas->address);
+
+	return ret;
+}
+
+void do_acpi_s3(struct vm *vm, uint32_t pm1a_cnt_val,
+	uint32_t pm1b_cnt_val)
+{
+	uint32_t s1, s2;
+
+	acpi_gas_write(&vm->pm.sx_state_data->pm1a_cnt, pm1a_cnt_val);
+
+	if (vm->pm.sx_state_data->pm1b_cnt.address != 0)
+		acpi_gas_write(&vm->pm.sx_state_data->pm1b_cnt, pm1b_cnt_val);
+
+	while (1) {
+		/* polling PM1 state register to detect wether
+		 * the Sx state enter is interrupted by wakeup event.
+		 */
+		s1 = s2 = 0;
+
+		s1 = acpi_gas_read(&vm->pm.sx_state_data->pm1a_evt);
+
+		if (vm->pm.sx_state_data->pm1b_evt.address != 0) {
+			s2 = acpi_gas_read(&vm->pm.sx_state_data->pm1b_evt);
+			s1 |= s2;
+		}
+
+		/* According to ACPI spec 4.8.3.1.1 PM1 state register, the bit
+		 * WAK_STS(bit 15) is set if system will transition to working
+		 * state.
+		 */
+		if ((s1 & (1 << BIT_WAK_STS)) != 0)
+			break;
+	}
+}
+
+int enter_s3(struct vm *vm, uint32_t pm1a_cnt_val,
+	uint32_t pm1b_cnt_val)
+{
+	uint32_t pcpu_id;
+	uint64_t pmain_entry_saved;
+	uint64_t *pmain_entry;
+
+	if (vm->pm.sx_state_data == NULL) {
+		pr_err("No Sx state info avaiable. No Sx support");
+		return -1;
+	}
+
+	pause_vm(vm);	/* pause vm0 before suspend system */
+
+	pcpu_id = get_cpu_id();
+
+	/* offline all APs */
+	stop_cpus();
+
+	/* Trampoline code is relocatable now. We have to calculate
+	 * main_entry address with relocation base address
+	 */
+	pmain_entry =
+		(uint64_t *)(HPA2HVA(trampoline_start16_paddr) +
+		(uint64_t) main_entry);
+
+	/* Save default main entry and we will restore it after
+	 * back from S3. So the AP online could jmp to correct
+	 * main entry.
+	 */
+	pmain_entry_saved = *pmain_entry;
+	/* Set the main entry for resume from S3 state */
+	*pmain_entry = (uint64_t)restore_s3_context;
+
+	CPU_IRQ_DISABLE();
+	vmx_off(pcpu_id);
+
+	suspend_console();
+	suspend_ioapic();
+	suspend_iommu();
+	suspend_lapic();
+
+	__enter_s3(vm, pm1a_cnt_val, pm1b_cnt_val);
+
+	/* release the lock aquired in trampoline code */
+	spinlock_release(&trampoline_spinlock);
+
+	resume_lapic();
+	resume_iommu();
+	resume_ioapic();
+	resume_console();
+
+	exec_vmxon_instr(pcpu_id);
+	CPU_IRQ_ENABLE();
+
+	/* restore the default main entry */
+	*pmain_entry = pmain_entry_saved;
+
+	/* online all APs again */
+	start_cpus();
+
+	return 0;
+}
diff --git a/hypervisor/arch/x86/wakeup.S b/hypervisor/arch/x86/wakeup.S
index 59dc5c9eb..c22cd1811 100644
--- a/hypervisor/arch/x86/wakeup.S
+++ b/hypervisor/arch/x86/wakeup.S
@@ -3,6 +3,7 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 #include <vcpu.h>
+#include <spinlock.h>
 
    .text
    .align   8
@@ -10,6 +11,8 @@
    .extern    restore_msrs
    .extern    cpu_ctx
    .extern    load_gdtr_and_tr
+   .extern    do_acpi_s3
+   .extern    trampoline_spinlock
 
    .global    __enter_s3
 __enter_s3:
@@ -47,7 +50,18 @@ __enter_s3:
 
 	wbinvd
 
-	/* Will add the function call to enter Sx here*/
+	movq CPU_CONTEXT_OFFSET_RDX + cpu_ctx(%rip), %rdx  /* pm1b_cnt_val */
+	movq CPU_CONTEXT_OFFSET_RDI + cpu_ctx(%rip), %rdi  /* *vm */
+	movq CPU_CONTEXT_OFFSET_RSI + cpu_ctx(%rip), %rsi  /* pm1a_cnt_val */
+
+	call do_acpi_s3
+
+	/* if do_acpi_s3 returns, which means ACRN can't enter S3 state.
+	 * Then trampoline will not be executed and we need to acquire
+	 * trampoline_spinlock here to match release in enter_sleep
+	 */
+	mov $trampoline_spinlock, %rdi
+	spinlock_obtain(%rdi)
 
 
 /*
diff --git a/hypervisor/include/arch/x86/host_pm.h b/hypervisor/include/arch/x86/host_pm.h
index 98466f47b..f5fc7eae8 100644
--- a/hypervisor/include/arch/x86/host_pm.h
+++ b/hypervisor/include/arch/x86/host_pm.h
@@ -5,6 +5,10 @@
 
 #ifndef	HOST_PM_H
 
+#define	BIT_WAK_STS	15U
+
+int enter_s3(struct vm *vm, uint32_t pm1a_cnt_val,
+		uint32_t pm1b_cnt_val);
 extern void __enter_s3(struct vm *vm, uint32_t pm1a_cnt_val,
 		uint32_t pm1b_cnt_val);
 extern void restore_s3_context(void);