tcg: Clear plugin_mem_cbs on TB exit

Do this in cpu_tb_exec (normal exit) and cpu_loop_exit (exception),
adjacent to where we reset can_do_io.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1381
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230310195252.210956-2-richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230315174331.2959-12-alex.bennee@linaro.org>
Reviewed-by: Emilio Cota <cota@braap.org>

accel/tcg/cpu-exec-common.c

@@ -65,6 +65,8 @@ void cpu_loop_exit(CPUState *cpu)
 {
     /* Undo the setting in cpu_tb_exec.  */
     cpu->can_do_io = 1;
+    /* Undo any setting in generated code.  */
+    qemu_plugin_disable_mem_helpers(cpu);
     siglongjmp(cpu->jmp_env, 1);
 }
 

accel/tcg/cpu-exec.c

@@ -459,6 +459,7 @@ cpu_tb_exec(CPUState *cpu, TranslationBlock *itb, int *tb_exit)
     qemu_thread_jit_execute();
     ret = tcg_qemu_tb_exec(env, tb_ptr);
     cpu->can_do_io = 1;
+    qemu_plugin_disable_mem_helpers(cpu);
     /*
      * TODO: Delay swapping back to the read-write region of the TB
      * until we actually need to modify the TB.  The read-only copy,
@@ -526,7 +527,6 @@ static void cpu_exec_exit(CPUState *cpu)
     if (cc->tcg_ops->cpu_exec_exit) {
         cc->tcg_ops->cpu_exec_exit(cpu);
     }
-    QEMU_PLUGIN_ASSERT(cpu->plugin_mem_cbs == NULL);
 }
 
 void cpu_exec_step_atomic(CPUState *cpu)
@@ -580,7 +580,6 @@ void cpu_exec_step_atomic(CPUState *cpu)
             qemu_mutex_unlock_iothread();
         }
         assert_no_pages_locked();
-        qemu_plugin_disable_mem_helpers(cpu);
     }
 
     /*
@@ -1004,7 +1003,6 @@ cpu_exec_loop(CPUState *cpu, SyncClocks *sc)
 
             cpu_loop_exec_tb(cpu, tb, pc, &last_tb, &tb_exit);
 
-            QEMU_PLUGIN_ASSERT(cpu->plugin_mem_cbs == NULL);
             /* Try to align the host and virtual clocks
                if the guest is in advance */
             align_clocks(sc, cpu);
@@ -1029,7 +1027,6 @@ static int cpu_exec_setjmp(CPUState *cpu, SyncClocks *sc)
         if (qemu_mutex_iothread_locked()) {
             qemu_mutex_unlock_iothread();
         }
-        qemu_plugin_disable_mem_helpers(cpu);
 
         assert_no_pages_locked();
     }