diff --git a/hypervisor/arch/x86/guest/vmsr.c b/hypervisor/arch/x86/guest/vmsr.c
index c734ada5b..c73cc86f7 100644
--- a/hypervisor/arch/x86/guest/vmsr.c
+++ b/hypervisor/arch/x86/guest/vmsr.c
@@ -361,7 +361,7 @@ static int32_t write_pat_msr(struct acrn_vcpu *vcpu, uint64_t value)
 
 	for (i = 0U; i < 8U; i++) {
 		field = (value >> (i * 8U)) & 0xffUL;
-		if (pat_mem_type_invalid(field) || ((PAT_FIELD_RSV_BITS & field) != 0UL)) {
+		if (is_pat_mem_type_invalid(field)) {
 			pr_err("invalid guest IA32_PAT: 0x%016lx", value);
 			ret = -EINVAL;
 			break;
diff --git a/hypervisor/include/arch/x86/msr.h b/hypervisor/include/arch/x86/msr.h
index f0072b8d2..98e3f39bc 100644
--- a/hypervisor/include/arch/x86/msr.h
+++ b/hypervisor/include/arch/x86/msr.h
@@ -568,10 +568,13 @@
 /* Miscellaneous data */
 #define MSR_IA32_MISC_UNRESTRICTED_GUEST	(1U<<5U)
 
+/* 5 high-order bits in every field are reserved */
+#define PAT_FIELD_RSV_BITS			(0xF8UL)
+
 #ifndef ASSEMBLER
-static inline bool pat_mem_type_invalid(uint64_t x)
+static inline bool is_pat_mem_type_invalid(uint64_t x)
 {
-	return ((x & ~0x7UL) != 0UL || (x & 0x6UL) == 0x2UL);
+	return (((x & PAT_FIELD_RSV_BITS) != 0UL) || ((x & 0x6UL) == 0x2UL));
 }
 
 static inline bool is_x2apic_msr(uint32_t msr)
@@ -591,9 +594,6 @@ void update_msr_bitmap_x2apic_passthru(struct acrn_vcpu *vcpu);
 
 #endif /* ASSEMBLER */
 
-/* 5 high-order bits in every field are reserved */
-#define PAT_FIELD_RSV_BITS			(0xF8U)
-
 #define PAT_POWER_ON_VALUE	(PAT_MEM_TYPE_WB + \
 	(PAT_MEM_TYPE_WT << 8U) + \
 	(PAT_MEM_TYPE_UCM << 16U) + \