diff --git a/xen/arch/x86/cpu/mtrr/generic.c b/xen/arch/x86/cpu/mtrr/generic.c
index ea0efe2f2e..8839f8d8e0 100644
--- a/xen/arch/x86/cpu/mtrr/generic.c
+++ b/xen/arch/x86/cpu/mtrr/generic.c
@@ -91,7 +91,6 @@ static const char *__init mtrr_attrib_to_str(mtrr_type x)
 {
 	static const char __initconst strings[MTRR_NUM_TYPES][16] =
 	{
-		[0 ... MTRR_NUM_TYPES - 1] = "?",
 		[MTRR_TYPE_UNCACHABLE]     = "uncachable",
 		[MTRR_TYPE_WRCOMB]         = "write-combining",
 		[MTRR_TYPE_WRTHROUGH]      = "write-through",
@@ -99,7 +98,7 @@ static const char *__init mtrr_attrib_to_str(mtrr_type x)
 		[MTRR_TYPE_WRBACK]         = "write-back",
 	};
 
-	return x < MTRR_NUM_TYPES ? strings[x] : "?";
+	return x < MTRR_NUM_TYPES ? (strings[x] ?: "?") : "?";
 }
 
 static unsigned int __initdata last_fixed_start;
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index c094320b2f..c5fe906da9 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -1201,6 +1201,20 @@ void ept_p2m_uninit(struct p2m_domain *p2m)
     free_cpumask_var(ept->invalidate);
 }
 
+static const char *memory_type_to_str(unsigned int x)
+{
+    static const char memory_types[8][2] = {
+        [MTRR_TYPE_UNCACHABLE]     = "UC",
+        [MTRR_TYPE_WRCOMB]         = "WC",
+        [MTRR_TYPE_WRTHROUGH]      = "WT",
+        [MTRR_TYPE_WRPROT]         = "WP",
+        [MTRR_TYPE_WRBACK]         = "WB",
+        [MTRR_NUM_TYPES]           = "??"
+    };
+
+    return x < ARRAY_SIZE(memory_types) ? (memory_types[x] ?: "?") : "?";
+}
+
 static void ept_dump_p2m_table(unsigned char key)
 {
     struct domain *d;
@@ -1212,15 +1226,6 @@ static void ept_dump_p2m_table(unsigned char key)
     unsigned long record_counter = 0;
     struct p2m_domain *p2m;
     struct ept_data *ept;
-    static const char memory_types[8][2] = {
-        [0 ... 7] = "?",
-        [MTRR_TYPE_UNCACHABLE]     = "UC",
-        [MTRR_TYPE_WRCOMB]         = "WC",
-        [MTRR_TYPE_WRTHROUGH]      = "WT",
-        [MTRR_TYPE_WRPROT]         = "WP",
-        [MTRR_TYPE_WRBACK]         = "WB",
-        [MTRR_NUM_TYPES]           = "??"
-    };
 
     for_each_domain(d)
     {
@@ -1260,8 +1265,8 @@ static void ept_dump_p2m_table(unsigned char key)
                            ept_entry->r ? 'r' : ' ',
                            ept_entry->w ? 'w' : ' ',
                            ept_entry->x ? 'x' : ' ',
-                           memory_types[ept_entry->emt][0],
-                           memory_types[ept_entry->emt][1]
+                           memory_type_to_str(ept_entry->emt)[0],
+                           memory_type_to_str(ept_entry->emt)[1]
                            ?: ept_entry->emt + '0',
                            c ?: ept_entry->ipat ? '!' : ' ');