hv: guest: fix "Procedure has more than one exit point"

IEC 61508,ISO 26262 standards highly recommend single-exit rule.

Reduce the count of the "return entries".
Fix the violations which is comply with the cases list below:
1.Function has 2 return entries.
2.The first return entry is used to return the error code of
checking variable whether is valid.

Fix the violations in "if else" format.

Tracked-On: #861
Signed-off-by: Huihuang Shi <huihuang.shi@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/arch/x86/guest/instr_emul.c

@@ -1462,12 +1462,10 @@ static int emulate_sub(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
 		break;
 	}
 
-	if (error != 0) {
+	if (error == 0) {
-		return error;
-	}
-
 		rflags2 = getcc(size, val1, val2);
 		vie_update_rflags(vcpu, rflags2, RFLAGS_STATUS_BITS);
+	}
 
 	return error;
 }
@@ -1494,11 +1492,12 @@ static int emulate_group1(struct acrn_vcpu *vcpu, const struct instr_emul_vie *v
 	return error;
 }
 
-static int emulate_bittest(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
+static int32_t emulate_bittest(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
 {
 	uint64_t val, rflags, bitmask;
 	uint64_t bitoff;
 	uint8_t size;
+	int32_t ret;
 
 	/*
 	 * 0F BA is a Group 8 extended opcode.
@@ -1506,10 +1505,7 @@ static int emulate_bittest(struct acrn_vcpu *vcpu, const struct instr_emul_vie *
 	 * Currently we only emulate the 'Bit Test' instruction which is
 	 * identified by a ModR/M:reg encoding of 100b.
 	 */
-	if ((vie->reg & 7U) != 4U) {
+	if ((vie->reg & 7U) == 4U) {
-		return -EINVAL;
-	}
-
 		rflags = vm_get_register(vcpu, CPU_REG_RFLAGS);
 
 		vie_mmio_read(vcpu, &val);
@@ -1529,8 +1525,12 @@ static int emulate_bittest(struct acrn_vcpu *vcpu, const struct instr_emul_vie *
 		}
 		size = 8U;
 		vie_update_register(vcpu, CPU_REG_RFLAGS, rflags, size);
+		ret = 0;
+	} else {
+	        ret = -EINVAL;
+	}
 
-	return 0;
+	return ret;
 }
 
 static int vmm_emulate_instruction(struct instr_emul_ctxt *ctxt)
@@ -1539,9 +1539,7 @@ static int vmm_emulate_instruction(struct instr_emul_ctxt *ctxt)
 	struct acrn_vcpu *vcpu = ctxt->vcpu;
 	int error;
 
-	if (vie->decoded == 0U) {
+	if (vie->decoded != 0U) {
-		return -EINVAL;
-	}
 		switch (vie->op.op_type) {
 		case VIE_OP_TYPE_GROUP1:
 			error = emulate_group1(vcpu, vie);
@@ -1581,6 +1579,10 @@ static int vmm_emulate_instruction(struct instr_emul_ctxt *ctxt)
 			error = -EINVAL;
 			break;
 		}
+	} else {
+		error = -EINVAL;
+	}
+
 	return error;
 }
 
@@ -2141,19 +2143,21 @@ static int local_decode_instruction(enum vm_cpu_mode cpu_mode,
 }
 
 /* for instruction MOVS/STO, check the gva gotten from DI/SI. */
-static int instr_check_di(struct acrn_vcpu *vcpu, struct instr_emul_ctxt *emul_ctxt)
+static int32_t instr_check_di(struct acrn_vcpu *vcpu, struct instr_emul_ctxt *emul_ctxt)
 {
-	int ret;
+	int32_t ret;
 	struct instr_emul_vie *vie = &emul_ctxt->vie;
 	uint64_t gva;
 
 	ret = get_gva_di_check(vcpu, vie, vie->addrsize, &gva);
 
 	if (ret < 0) {
-		return -EFAULT;
+		ret = -EFAULT;
+	} else {
+		ret = 0;
 	}
 
-	return 0;
+	return ret;
 }
 
 static int instr_check_gva(struct acrn_vcpu *vcpu, struct instr_emul_ctxt *emul_ctxt,
@@ -2305,14 +2309,17 @@ int decode_instruction(struct acrn_vcpu *vcpu)
 	return (int)(emul_ctxt->vie.opsize);
 }
 
-int emulate_instruction(const struct acrn_vcpu *vcpu)
+int32_t emulate_instruction(const struct acrn_vcpu *vcpu)
 {
 	struct instr_emul_ctxt *ctxt = &per_cpu(g_inst_ctxt, vcpu->pcpu_id);
+	int32_t ret;
 
 	if (ctxt == NULL) {
 		pr_err("%s: Failed to get instr_emul_ctxt", __func__);
-		return -1;
+		ret = -1;
+	} else {
+		ret = vmm_emulate_instruction(ctxt); 
 	}
 
-	return vmm_emulate_instruction(ctxt);
+	return ret;
 }

hypervisor/arch/x86/guest/instr_emul.h

@@ -193,7 +193,7 @@ struct instr_emul_ctxt {
 	struct acrn_vcpu *vcpu;
 };
 
-int emulate_instruction(const struct acrn_vcpu *vcpu);
+int32_t emulate_instruction(const struct acrn_vcpu *vcpu);
 int decode_instruction(struct acrn_vcpu *vcpu);
 
 #endif

hypervisor/arch/x86/guest/pm.c

@@ -39,11 +39,8 @@ static void vm_setup_cpu_px(struct acrn_vm *vm)
 	(void)memset(vm->pm.px_data, 0U,
 			MAX_PSTATE * sizeof(struct cpu_px_data));
 
-	if ((boot_cpu_data.state_info.px_cnt == 0U)
+	if ((boot_cpu_data.state_info.px_cnt != 0U)
-		|| (boot_cpu_data.state_info.px_data == NULL)) {
+		&& (boot_cpu_data.state_info.px_data != NULL)) {
-		return;
-	}
-
 		ASSERT ((boot_cpu_data.state_info.px_cnt <= MAX_PSTATE),
 			"failed to setup cpu px");
 
@@ -53,7 +50,7 @@ static void vm_setup_cpu_px(struct acrn_vm *vm)
 
 		(void)memcpy_s(vm->pm.px_data, px_data_size,
 				boot_cpu_data.state_info.px_data, px_data_size);
-
+	}
 }
 
 static void vm_setup_cpu_cx(struct acrn_vm *vm)
@@ -64,11 +61,8 @@ static void vm_setup_cpu_cx(struct acrn_vm *vm)
 	(void)memset(vm->pm.cx_data, 0U,
 			MAX_CSTATE * sizeof(struct cpu_cx_data));
 
-	if ((boot_cpu_data.state_info.cx_cnt == 0U)
+	if ((boot_cpu_data.state_info.cx_cnt != 0U)
-		|| (boot_cpu_data.state_info.cx_data == NULL)) {
+		&& (boot_cpu_data.state_info.cx_data != NULL)) {
-		return;
-	}
-
 		ASSERT ((boot_cpu_data.state_info.cx_cnt <= MAX_CX_ENTRY),
 			"failed to setup cpu cx");
 
@@ -81,7 +75,7 @@ static void vm_setup_cpu_cx(struct acrn_vm *vm)
 		 */
 		(void)memcpy_s(vm->pm.cx_data + 1, cx_data_size,
 				boot_cpu_data.state_info.cx_data, cx_data_size);
-
+	}
 }
 
 static inline void init_cx_port(struct acrn_vm *vm)
@@ -192,13 +186,10 @@ register_gas_io_handler(struct acrn_vm *vm, uint32_t pio_idx, const struct acpi_
 	uint8_t io_len[5] = {0, 1, 2, 4, 8};
 	struct vm_io_range gas_io;
 
-	if ((gas->address == 0UL)
+	if ((gas->address != 0UL)
-			|| (gas->space_id != SPACE_SYSTEM_IO)
+			&& (gas->space_id == SPACE_SYSTEM_IO)
-			|| (gas->access_size == 0U)
+			&& (gas->access_size != 0U)
-			|| (gas->access_size > 4U)) {
+			&& (gas->access_size <= 4U)) {
-		return;
-	}
-
 		gas_io.flags = IO_ATTR_RW;
 		gas_io.base = (uint16_t)gas->address;
 		gas_io.len = io_len[gas->access_size];
@@ -208,6 +199,7 @@ register_gas_io_handler(struct acrn_vm *vm, uint32_t pio_idx, const struct acpi_
 
 		pr_dbg("Enable PM1A trap for VM %d, port 0x%x, size %d\n",
 				vm->vm_id, gas_io.base, gas_io.len);
+	}
 }
 
 void register_pm1ab_handler(struct acrn_vm *vm)

hypervisor/arch/x86/guest/vm.c

@@ -45,11 +45,15 @@ static inline bool is_vm_valid(uint16_t vm_id)
  */
 struct acrn_vm *get_vm_from_vmid(uint16_t vm_id)
 {
+	struct acrn_vm *ret;
+
 	if (is_vm_valid(vm_id)) {
-		return &vm_array[vm_id];
+	        ret = &vm_array[vm_id];
 	} else {
-		return NULL;
+	        ret = NULL;
 	}
+
+	return ret;
 }
 
 /**
@@ -188,19 +192,16 @@ err:
 /*
  * @pre vm != NULL
  */
-int shutdown_vm(struct acrn_vm *vm)
+int32_t shutdown_vm(struct acrn_vm *vm)
 {
-	int status = 0;
 	uint16_t i;
 	struct acrn_vcpu *vcpu = NULL;
+	int32_t ret;
 
 	pause_vm(vm);
 
 	/* Only allow shutdown paused vm */
-	if (vm->state != VM_PAUSED) {
+	if (vm->state == VM_PAUSED) {
-		return -EINVAL;
-	}
-
 		foreach_vcpu(i, vm, vcpu) {
 			reset_vcpu(vcpu);
 			offline_vcpu(vcpu);
@@ -220,9 +221,13 @@ int shutdown_vm(struct acrn_vm *vm)
 		free_vm_id(vm);
 
 		vpci_cleanup(vm);
+		ret = 0;
+	} else {
+	        ret = -EINVAL;
+	}
 
 	/* Return status to caller */
-	return status;
+	return ret;
 }
 
 /**
@@ -244,15 +249,13 @@ int start_vm(struct acrn_vm *vm)
 /**
  *  * @pre vm != NULL
  */
-int reset_vm(struct acrn_vm *vm)
+int32_t reset_vm(struct acrn_vm *vm)
 {
 	uint16_t i;
 	struct acrn_vcpu *vcpu = NULL;
+	int32_t ret;
 
-	if (vm->state != VM_PAUSED) {
+	if (vm->state == VM_PAUSED) {
-		return -1;
-	}
-
 		foreach_vcpu(i, vm, vcpu) {
 			reset_vcpu(vcpu);
 		}
@@ -265,8 +268,12 @@ int reset_vm(struct acrn_vm *vm)
 		vioapic_reset(vm_ioapic(vm));
 		destroy_secure_world(vm, false);
 		vm->sworld_control.flag.active = 0UL;
+		ret = 0;
+	} else {
+		ret = -1;
+	}
 
-	return 0;
+	return ret;
 }
 
 /**
@@ -277,15 +284,13 @@ void pause_vm(struct acrn_vm *vm)
 	uint16_t i;
 	struct acrn_vcpu *vcpu = NULL;
 
-	if (vm->state == VM_PAUSED) {
+	if (vm->state != VM_PAUSED) {
-		return;
-	}
-
 		vm->state = VM_PAUSED;
 
 		foreach_vcpu(i, vm, vcpu) {
 			pause_vcpu(vcpu, VCPU_ZOMBIE);
 		}
+	}
 }
 
 /**