cpu: Call plugin hooks only when ready

The initialization and exit hooks will not affect the state of vCPU
outside TCG context, but they may depend on the state of vCPU.
Therefore, it's better to call plugin hooks after the vCPU state is
fully initialized and before it gets uninitialized.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20231025093128.33116-16-akihiko.odaki@daynix.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20231106185112.2755262-12-alex.bennee@linaro.org>

cpu-target.c

@@ -42,7 +42,6 @@
 #include "hw/core/accel-cpu.h"
 #include "trace/trace-root.h"
 #include "qemu/accel.h"
-#include "qemu/plugin.h"
 
 uintptr_t qemu_host_page_size;
 intptr_t qemu_host_page_mask;
@@ -143,11 +142,6 @@ bool cpu_exec_realizefn(CPUState *cpu, Error **errp)
     /* Wait until cpu initialization complete before exposing cpu. */
     cpu_list_add(cpu);
 
-    /* Plugin initialization must wait until cpu_index assigned. */
-    if (tcg_enabled()) {
-        qemu_plugin_vcpu_init_hook(cpu);
-    }
-
 #ifdef CONFIG_USER_ONLY
     assert(qdev_get_vmsd(DEVICE(cpu)) == NULL ||
            qdev_get_vmsd(DEVICE(cpu))->unmigratable);
@@ -176,11 +170,6 @@ void cpu_exec_unrealizefn(CPUState *cpu)
     }
 #endif
 
-    /* Call the plugin hook before clearing cpu->cpu_index in cpu_list_remove */
-    if (tcg_enabled()) {
-        qemu_plugin_vcpu_exit_hook(cpu);
-    }
-
     cpu_list_remove(cpu);
     /*
      * Now that the vCPU has been removed from the RCU list, we can call

hw/core/cpu-common.c

@@ -214,13 +214,23 @@ static void cpu_common_realizefn(DeviceState *dev, Error **errp)
         cpu_resume(cpu);
     }
 
+    /* Plugin initialization must wait until the cpu is fully realized. */
+    if (tcg_enabled()) {
+        qemu_plugin_vcpu_init_hook(cpu);
+    }
+
     /* NOTE: latest generic point where the cpu is fully realized */
 }
 
 static void cpu_common_unrealizefn(DeviceState *dev)
 {
     CPUState *cpu = CPU(dev);
 
+    /* Call the plugin hook before clearing the cpu is fully unrealized */
+    if (tcg_enabled()) {
+        qemu_plugin_vcpu_exit_hook(cpu);
+    }
+
     /* NOTE: latest generic point before the cpu is fully unrealized */
     cpu_exec_unrealizefn(cpu);
 }