migration: Move cpu-throttle.c from system to migration

Move cpu-throttle.c from system to migration since it's
only used for migration; this makes us avoid exporting the
util functions and variables in misc.h but export them in
migration.h when implementing the periodic ramblock dirty
sync feature in the upcoming commits.

Since CPU throttle timers are only used in migration, move
their registry to migration_object_init.

Signed-off-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/c1b3efaa0cb49e03d422e9da97bdb65cc3d234d1.1729146786.git.yong.huang@smartx.com
[peterx: Fix build on MacOS on cocoa.m, not move cpu-throttle.h yet]
[peterx: Fix subject spelling, per pm215]
Signed-off-by: Peter Xu <peterx@redhat.com>

migration/meson.build

@@ -13,6 +13,7 @@ system_ss.add(files(
   'block-dirty-bitmap.c',
   'channel.c',
   'channel-block.c',
+  'cpu-throttle.c',
   'dirtyrate.c',
   'exec.c',
   'fd.c',

migration/migration.c

@@ -263,6 +263,9 @@ void migration_object_init(void)
 
     ram_mig_init();
     dirty_bitmap_mig_init();
+
+    /* Initialize cpu throttle timers */
+    cpu_throttle_init();
 }
 
 typedef struct {

migration/trace-events

@@ -378,3 +378,6 @@ migration_block_progression(unsigned percent) "Completed %u%%"
 # page_cache.c
 migration_pagecache_init(int64_t max_num_items) "Setting cache buckets to %" PRId64
 migration_pagecache_insert(void) "Error allocating page"
+
+# cpu-throttle.c
+cpu_throttle_set(int new_throttle_pct)  "set guest CPU throttled by %d%%"

system/cpu-timers.c

@@ -35,7 +35,6 @@
 #include "sysemu/runstate.h"
 #include "hw/core/cpu.h"
 #include "sysemu/cpu-timers.h"
-#include "sysemu/cpu-throttle.h"
 #include "sysemu/cpu-timers-internal.h"
 
 /* clock and ticks */
@@ -272,6 +271,4 @@ void cpu_timers_init(void)
     seqlock_init(&timers_state.vm_clock_seqlock);
     qemu_spin_init(&timers_state.vm_clock_lock);
     vmstate_register(NULL, 0, &vmstate_timers, &timers_state);
-
-    cpu_throttle_init();
 }

system/meson.build

@@ -10,7 +10,6 @@ system_ss.add(files(
   'balloon.c',
   'bootdevice.c',
   'cpus.c',
-  'cpu-throttle.c',
   'cpu-timers.c',
   'datadir.c',
   'dirtylimit.c',

system/trace-events

@@ -44,6 +44,3 @@ dirtylimit_state_finalize(void)
 dirtylimit_throttle_pct(int cpu_index, uint64_t pct, int64_t time_us) "CPU[%d] throttle percent: %" PRIu64 ", throttle adjust time %"PRIi64 " us"
 dirtylimit_set_vcpu(int cpu_index, uint64_t quota) "CPU[%d] set dirty page rate limit %"PRIu64
 dirtylimit_vcpu_execute(int cpu_index, int64_t sleep_time_us) "CPU[%d] sleep %"PRIi64 " us"
-
-# cpu-throttle.c
-cpu_throttle_set(int new_throttle_pct)  "set guest CPU throttled by %d%%"