plugins: create CPUPluginState and migrate plugin_mask

As we expand the per-vCPU data for plugins we don't want to pollute
CPUState. For now this just moves the plugin_mask (renamed to
event_mask) as the memory callbacks are accessed directly by TCG
generated code.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240227144335.1196131-23-alex.bennee@linaro.org>

include/hw/core/cpu.h

@@ -31,7 +31,6 @@
 #include "qemu/rcu_queue.h"
 #include "qemu/queue.h"
 #include "qemu/thread.h"
-#include "qemu/plugin-event.h"
 #include "qom/object.h"
 
 typedef int (*WriteCoreDumpFunction)(const void *buf, size_t size,
@@ -434,7 +433,8 @@ struct qemu_work_item;
  * @kvm_fd: vCPU file descriptor for KVM.
  * @work_mutex: Lock to prevent multiple access to @work_list.
  * @work_list: List of pending asynchronous work.
- * @plugin_mask: Plugin event bitmap. Modified only via async work.
+ * @plugin_mem_cbs: active plugin memory callbacks
+ * @plugin_state: per-CPU plugin state
  * @ignore_memory_transaction_failures: Cached copy of the MachineState
  *    flag of the same name: allows the board to suppress calling of the
  *    CPU do_transaction_failed hook function.
@@ -526,10 +526,13 @@ struct CPUState {
     /* Use by accel-block: CPU is executing an ioctl() */
     QemuLockCnt in_ioctl_lock;
 
-    DECLARE_BITMAP(plugin_mask, QEMU_PLUGIN_EV_MAX);
-
 #ifdef CONFIG_PLUGIN
+    /*
+     * The callback pointer stays in the main CPUState as it is
+     * accessed via TCG (see gen_empty_mem_helper).
+     */
     GArray *plugin_mem_cbs;
+    CPUPluginState *plugin_state;
 #endif
 
     /* TODO Move common fields from CPUArchState here. */