Add API to check whether paging mode is enabled

This API will be used in the following patch.
Signed-off-by: NWen Congyang <wency@cn.fujitsu.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

cpu-all.h

@@ -527,12 +527,18 @@ int cpu_memory_rw_debug(CPUArchState *env, target_ulong addr,
 
 #if defined(CONFIG_HAVE_GET_MEMORY_MAPPING)
 int cpu_get_memory_mapping(MemoryMappingList *list, CPUArchState *env);
+bool cpu_paging_enabled(CPUArchState *env);
 #else
 static inline int cpu_get_memory_mapping(MemoryMappingList *list,
                                          CPUArchState *env)
 {
     return -1;
 }
+
+static inline bool cpu_paging_enabled(CPUArchState *env)
+{
+    return true;
+}
 #endif
 
 #endif /* CPU_ALL_H */

target-i386/arch_memory_mapping.c

@@ -233,7 +233,7 @@ static void walk_pml4e(MemoryMappingList *list,
 
 int cpu_get_memory_mapping(MemoryMappingList *list, CPUArchState *env)
 {
-    if (!(env->cr[0] & CR0_PG_MASK)) {
+    if (!cpu_paging_enabled(env)) {
         /* paging is disabled */
         return 0;
     }
@@ -264,3 +264,8 @@ int cpu_get_memory_mapping(MemoryMappingList *list, CPUArchState *env)
 
     return 0;
 }
+
+bool cpu_paging_enabled(CPUArchState *env)
+{
+    return env->cr[0] & CR0_PG_MASK;
+}