diff --git a/target/hexagon/cpu.h b/target/hexagon/cpu.h
index f7d043865b..f90c187888 100644
--- a/target/hexagon/cpu.h
+++ b/target/hexagon/cpu.h
@@ -141,6 +141,15 @@ static inline void cpu_get_tb_cpu_state(CPUHexagonState *env, target_ulong *pc,
 #endif
 }
 
+static inline int cpu_mmu_index(CPUHexagonState *env, bool ifetch)
+{
+#ifdef CONFIG_USER_ONLY
+    return MMU_USER_IDX;
+#else
+#error System mode not supported on Hexagon yet
+#endif
+}
+
 typedef struct CPUHexagonState CPUArchState;
 typedef HexagonCPU ArchCPU;