hv: remove the theoretic infinite loop

There may the theoretic infinite loop with some code. But actually it doesn't.
This patch make these code more obvious it's not a potentially infinite loop.

Tracked-On: #861
Signed-off-by: Li, Fei1 <fei1.li@intel.com>

hypervisor/arch/x86/guest/instr_emul.c

@@ -1669,9 +1669,9 @@ static bool segment_override(uint8_t x, enum cpu_reg_name *seg)
 static int decode_prefixes(struct instr_emul_vie *vie,
 					enum vm_cpu_mode cpu_mode, bool cs_d)
 {
-	uint8_t x;
+	uint8_t x, i;
 
-	while (1) {
+	for (i = 0U; i < VIE_PREFIX_SIZE; i++) {
 		if (vie_peek(vie, &x) != 0) {
 			return -1;
 		}

hypervisor/arch/x86/guest/instr_emul.h

@@ -87,7 +87,8 @@ struct instr_emul_vie_op {
 	uint16_t	op_flags;
 };
 
-#define	VIE_INST_SIZE	15U
+#define VIE_PREFIX_SIZE	4U
+#define VIE_INST_SIZE	15U
 struct instr_emul_vie {
 	uint8_t		inst[VIE_INST_SIZE];	/* instruction bytes */
 	uint8_t		num_valid;		/* size of the instruction */

hypervisor/arch/x86/notify.c

@@ -35,8 +35,7 @@ void smp_call_function(uint64_t mask, smp_call_func_t func, void *data)
 	struct smp_call_info_data *smp_call;
 
 	/* wait for previous smp call complete, which may run on other cpus */
-	while (atomic_cmpxchg64(&smp_call_mask, 0UL, mask & INVALID_BIT_INDEX)
-									!= 0UL);
+	while (atomic_cmpxchg64(&smp_call_mask, 0UL, mask & INVALID_BIT_INDEX) != 0UL);
 	pcpu_id = ffs64(mask);
 	while (pcpu_id != INVALID_BIT_INDEX) {
 		bitmap_clear_nolock(pcpu_id, &mask);

hypervisor/arch/x86/pm.c

@@ -99,7 +99,7 @@ void do_acpi_s3(struct acrn_vm *vm, uint32_t pm1a_cnt_val,
 		acpi_gas_write(&(sx_data->pm1b_cnt), pm1b_cnt_val);
 	}
 
-	while (1) {
+	do {
 		/* polling PM1 state register to detect wether
 		 * the Sx state enter is interrupted by wakeup event.
 		 */
@@ -117,10 +117,7 @@ void do_acpi_s3(struct acrn_vm *vm, uint32_t pm1a_cnt_val,
 		 * WAK_STS(bit 15) is set if system will transition to working
 		 * state.
 		 */
-		if ((s1 & (1U << BIT_WAK_STS)) != 0U) {
-			break;
-		}
-	}
+	} while ((s1 & (1U << BIT_WAK_STS)) == 0U);
 }
 
 void enter_s3(struct acrn_vm *vm, uint32_t pm1a_cnt_val, uint32_t pm1b_cnt_val)

hypervisor/common/softirq.c

@@ -32,18 +32,14 @@ void fire_softirq(uint16_t nr)
 
 void do_softirq(void)
 {
-	uint16_t nr;
 	uint16_t cpu_id = get_cpu_id();
 	volatile uint64_t *softirq_pending_bitmap =
 			&per_cpu(softirq_pending, cpu_id);
+	uint16_t nr = ffs64(*softirq_pending_bitmap);
 
-	while (true) {
-		nr = ffs64(*softirq_pending_bitmap);
-		if (nr >= NR_SOFTIRQS) {
-			break;
-		}
-
+	while (nr < NR_SOFTIRQS) {
 		bitmap_clear_lock(nr, softirq_pending_bitmap);
 		(*softirq_handlers[nr])(cpu_id);
+		nr = ffs64(*softirq_pending_bitmap);
 	}
 }

hypervisor/lib/string.c

@@ -14,6 +14,21 @@ static inline bool is_space(char c)
 	return ((c == ' ') || (c == '\t'));
 }
 
+static inline char hex_digit_value (char ch)
+{
+	char c;
+	if ('0' <= ch && ch <= '9') {
+		c = ch - '0';
+	} else if ('a' <= ch && ch <= 'f') {
+		c = ch - 'a' + 10;
+	} else if ('A' <= ch && ch <= 'F') {
+		c = ch - 'A' + 10;
+	} else {
+		c = -1;
+	}
+	return c;
+}
+
 /*
  * Convert a string to a long integer - decimal support only.
  */
@@ -99,7 +114,7 @@ long strtol_deci(const char *nptr)
 uint64_t strtoul_hex(const char *nptr)
 {
 	const char *s = nptr;
-	char c;
+	char c, digit;
 	uint64_t acc, cutoff, cutlim;
 	uint64_t base = 16UL;
 	int any;
@@ -121,29 +136,20 @@ uint64_t strtoul_hex(const char *nptr)
 	cutlim = ULONG_MAX % base;
 	acc = 0UL;
 	any = 0;
-	do {
-		if ((c >= '0') && (c <= '9')) {
-			c -= '0';
-		} else if ((c >= 'A') && (c <= 'F')) {
-			c -= 'A' - 10;
-		} else if ((c >= 'a') && (c <= 'f')) {
-			c -= 'a' - 10;
-		} else {
-			break;
-		}
-
-		if ((acc > cutoff) ||
-			((acc == cutoff) && ((uint64_t)c > cutlim))) {
+	digit = hex_digit_value(c);
+	while (digit >= 0) {
+		if ((acc > cutoff) || ((acc == cutoff) && ((uint64_t)digit > cutlim))) {
 			any = -1;
 			break;
 		} else {
 			acc *= base;
-			acc += c;
+			acc += digit;
 		}
 
 		c = *s;
 		s++;
-	} while (true);
+		digit = hex_digit_value(c);
+	}
 
 	if (any < 0) {
 		acc = ULONG_MAX;