hv: refine a few functions to only one exit point

IEC 61508,ISO 26262 standards highly recommend single-exit rule.
7C: Procedure has more than one exit point.

Tracked-On: #861
Signed-off-by: Zide Chen <zide.chen@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>

hypervisor/arch/x86/guest/vmtrr.c

@@ -44,10 +44,11 @@ static uint32_t get_index_of_fixed_mtrr(uint32_t msr)
 
 	for (i = 0U; i < FIXED_RANGE_MTRR_NUM; i++) {
 		if (fixed_mtrr_map[i].msr == msr) {
-			return i;
+			break;
 		}
 	}
-	return FIXED_MTRR_INVALID_INDEX;
+
+	return (i < FIXED_RANGE_MTRR_NUM) ? i : FIXED_MTRR_INVALID_INDEX;
 }
 
 static uint32_t

hypervisor/dm/vioapic.c

@@ -55,26 +55,23 @@ vioapic_send_intr(struct acrn_vioapic *vioapic, uint32_t pin)
 
 	if ((rte.full & IOAPIC_RTE_INTMASK) == IOAPIC_RTE_INTMSET) {
 		dev_dbg(ACRN_DBG_IOAPIC, "ioapic pin%hhu: masked", pin);
-		return;
+	} else {
-	}
-
 		phys = ((rte.full & IOAPIC_RTE_DESTMOD) == IOAPIC_RTE_DESTPHY);
 		delmode = (uint32_t)(rte.full & IOAPIC_RTE_DELMOD);
 		level = ((rte.full & IOAPIC_RTE_TRGRLVL) != 0UL);
+
 		/* For level trigger irq, avoid send intr if
 		 * previous one hasn't received EOI
 		 */
+		if (!level || ((vioapic->rtbl[pin].full & IOAPIC_RTE_REM_IRR) == 0UL)) {
 			if (level) {
-		if ((vioapic->rtbl[pin].full & IOAPIC_RTE_REM_IRR) != 0UL) {
-			return;
-		}
 				vioapic->rtbl[pin].full |= IOAPIC_RTE_REM_IRR;
 			}
-
 			vector = rte.u.lo_32 & IOAPIC_RTE_LOW_INTVEC;
 			dest = (uint32_t)(rte.full >> IOAPIC_RTE_DEST_SHIFT);
-	vlapic_deliver_intr(vioapic->vm, level, dest, phys,
+			vlapic_deliver_intr(vioapic->vm, level, dest, phys, delmode, vector, false);
-							delmode, vector, false);
+		}
+	}
 }
 
 /**
@@ -216,18 +213,20 @@ vioapic_update_tmr(struct acrn_vcpu *vcpu)
 static uint32_t
 vioapic_indirect_read(const struct acrn_vioapic *vioapic, uint32_t addr)
 {
-	uint32_t regnum;
+	uint32_t regnum, ret = 0U;
 	uint32_t pin, pincount = vioapic_pincount(vioapic->vm);
 
 	regnum = addr & 0xffU;
 	switch (regnum) {
 	case IOAPIC_ID:
-		return vioapic->id;
+		ret = vioapic->id;
+		break;
 	case IOAPIC_VER:
-		return (((uint32_t)pincount - 1U) << MAX_RTE_SHIFT) |
+		ret = (((uint32_t)pincount - 1U) << MAX_RTE_SHIFT) | ACRN_IOAPIC_VERSION;
-						ACRN_IOAPIC_VERSION;
+		break;
 	case IOAPIC_ARB:
-		return vioapic->id;
+		ret = vioapic->id;
+		break;
 	default:
 		/*
 		 * In this switch statement, regnum shall either be IOAPIC_ID or
@@ -245,13 +244,13 @@ vioapic_indirect_read(const struct acrn_vioapic *vioapic, uint32_t addr)
 		uint32_t rte_offset = addr_offset >> 1U;
 		pin = rte_offset;
 		if ((addr_offset & 0x1U) != 0U) {
-			return vioapic->rtbl[pin].u.hi_32;
+			ret = vioapic->rtbl[pin].u.hi_32;
 		} else {
-			return vioapic->rtbl[pin].u.lo_32;
+			ret = vioapic->rtbl[pin].u.lo_32;
 		}
 	}
 
-	return 0;
+	return ret;
 }
 
 static inline bool vioapic_need_intr(const struct acrn_vioapic *vioapic, uint16_t pin)

hypervisor/dm/vpic.c

@@ -49,6 +49,7 @@ static inline bool master_pic(const struct acrn_vpic *vpic, struct i8259_reg_sta
 static inline uint8_t vpic_get_highest_isrpin(const struct i8259_reg_state *i8259)
 {
 	uint8_t bit, pin, i;
+	uint8_t found_pin = VPIC_INVALID_PIN;
 
 	pin = (i8259->lowprio + 1U) & 0x7U;
 
@@ -64,18 +65,20 @@ static inline uint8_t vpic_get_highest_isrpin(const struct i8259_reg_state *i825
 				pin = (pin + 1U) & 0x7U;
 				continue;
 			} else {
-				return pin;
+				found_pin = pin;
+				break;
 			}
 		}
 		pin = (pin + 1U) & 0x7U;
 	}
 
-	return VPIC_INVALID_PIN;
+	return found_pin;
 }
 
 static inline uint8_t vpic_get_highest_irrpin(const struct i8259_reg_state *i8259)
 {
 	uint8_t serviced, bit, pin, tmp;
+	uint8_t found_pin = VPIC_INVALID_PIN;
 
 	/*
 	 * In 'Special Fully-Nested Mode' when an interrupt request from
@@ -115,13 +118,14 @@ static inline uint8_t vpic_get_highest_irrpin(const struct i8259_reg_state *i825
 		 * the corresponding 'pin' to the caller.
 		 */
 		if (((i8259->request & bit) != 0) && ((i8259->mask & bit) == 0)) {
-			return pin;
+			found_pin = pin;
+			break;
 		}
 
 		pin = (pin + 1U) & 0x7U;
 	}
 
-	return VPIC_INVALID_PIN;
+	return found_pin;
 }
 
 static void vpic_notify_intr(struct acrn_vpic *vpic)
@@ -457,18 +461,12 @@ void vpic_set_irq(struct acrn_vm *vm, uint32_t irq, uint32_t operation)
 	struct i8259_reg_state *i8259;
 	uint8_t pin;
 
-	if (irq >= NR_VPIC_PINS_TOTAL) {
+	if (irq < NR_VPIC_PINS_TOTAL) {
-		return;
-	}
-
 		vpic = vm_pic(vm);
 		i8259 = &vpic->i8259[irq >> 3U];
 		pin = (uint8_t)irq;
 
-	if (i8259->ready == false) {
+		if (i8259->ready) {
-		return;
-	}
-
 			spinlock_obtain(&(vpic->lock));
 			switch (operation) {
 			case GSI_SET_HIGH:
@@ -493,6 +491,8 @@ void vpic_set_irq(struct acrn_vm *vm, uint32_t irq, uint32_t operation)
 			}
 			vpic_notify_intr(vpic);
 			spinlock_release(&(vpic->lock));
+		}
+	}
 }
 
 uint32_t