cpu: add APIs to allocate/free CPU environment

These will be implemented and then used by follow-up patches.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

include/qom/cpu.h

@@ -162,6 +162,10 @@ typedef struct CPUClass {
     void (*dump_statistics)(CPUState *cpu, FILE *f,
                             fprintf_function cpu_fprintf, int flags);
     int64_t (*get_arch_id)(CPUState *cpu);
+    void * (*alloc_env)(CPUState *cpu);
+    void (*get_env)(CPUState *cpu, void *env);
+    void (*set_env)(CPUState *cpu, void *env);
+    void (*free_env)(CPUState *cpu, void *env);
     bool (*get_paging_enabled)(const CPUState *cpu);
     void (*get_memory_mapping)(CPUState *cpu, MemoryMappingList *list,
                                Error **errp);
@@ -439,6 +443,33 @@ static inline void cpu_tb_jmp_cache_clear(CPUState *cpu)
 extern bool mttcg_enabled;
 #define qemu_tcg_mttcg_enabled() (mttcg_enabled)
 
+/**
+ * cpu_alloc_env: allocate CPU environment structure
+ * @cpu: allocate environment structure for this CPU
+ */
+void *cpu_alloc_env(CPUState *cpu);
+
+/**
+ * cpu_get_env: retrieve CPU environment structure
+ * @cpu: CPU to use
+ * @env: environment structure to use
+ */
+void cpu_get_env(CPUState *cpu, void *env);
+
+/**
+ * cpu_set_env: switch to given CPU environment
+ * @cpu: CPU to use
+ * @env: environment structure to use
+ */
+void cpu_set_env(CPUState *cpu, void *env);
+
+/**
+ * cpu_free_env: free CPU environment structure
+ * @cpu: free environment structure for this CPU
+ * @env: structure to free
+ */
+void cpu_free_env(CPUState *cpu, void *env);
+
 /**
  * cpu_paging_enabled:
  * @cpu: The CPU whose state is to be inspected.

qom/cpu.c

@@ -89,6 +89,40 @@ CPUState *cpu_generic_init(const char *typename, const char *cpu_model)
     return cpu;
 }
 
+void *cpu_alloc_env(CPUState *cpu)
+{
+    CPUClass *cc = CPU_GET_CLASS(cpu);
+
+    return cc->alloc_env ? cc->alloc_env(cpu) : NULL;
+}
+
+void cpu_get_env(CPUState *cpu, void *env)
+{
+    CPUClass *cc = CPU_GET_CLASS(cpu);
+
+    if (cc->get_env) {
+        cc->get_env(cpu, env);
+    }
+}
+
+void cpu_set_env(CPUState *cpu, void *env)
+{
+    CPUClass *cc = CPU_GET_CLASS(cpu);
+
+    if (cc->set_env) {
+        cc->set_env(cpu, env);
+    }
+}
+
+void cpu_free_env(CPUState *cpu, void *env)
+{
+    CPUClass *cc = CPU_GET_CLASS(cpu);
+
+    if (cc->free_env) {
+        cc->free_env(cpu, env);
+    }
+}
+
 bool cpu_paging_enabled(const CPUState *cpu)
 {
     CPUClass *cc = CPU_GET_CLASS(cpu);