Merge tag 'migration-20241030-pull-request' of https://gitlab.com/peterx/qemu into staging

Migration pull request for softfreeze

v2:
- Patch "migration: Move cpu-throttle.c from system to migration",
  fix build on MacOS, and subject spelling

NOTE: checkpatch.pl could report a false positive on this branch:

  WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
  #21:
   {include/sysemu => migration}/cpu-throttle.h | 0

That's covered by "F: migration/" entry.

Changelog:

- Peter's cleanup patch on migrate_fd_cleanup()
- Peter's cleanup patch to introduce thread name macros
- Hanna's error path fix for vmstate subsection save()s
- Hyman's auto converge enhancement on background dirty sync
- Peter's additional tracepoints for save state entries
- Thomas's build fix for OpenBSD in dirtyrate.c
- Peter's deprecation of query-migrationthreads command
- Peter's cleanup/fixes from the "export misc.h" series
- Maciej's two small patches from multifd+vfio series

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# gpg: Signature made Fri 01 Nov 2024 13:44:53 GMT
# gpg:                using EDDSA key B9184DC20CC457DACF7DD1A93B5FCCCDF3ABD706
# gpg:                issuer "[email protected]"
# gpg: Good signature from "Peter Xu <[email protected]>" [marginal]
# gpg:                 aka "Peter Xu <[email protected]>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: B918 4DC2 0CC4 57DA CF7D  D1A9 3B5F CCCD F3AB D706

* tag 'migration-20241030-pull-request' of https://gitlab.com/peterx/qemu:
  migration/multifd: Zero p->flags before starting filling a packet
  migration/ram: Add load start trace event
  migration: Drop migration_is_idle()
  migration: Drop migration_is_setup_or_active()
  migration: Unexport ram_mig_init()
  migration: Unexport dirty_bitmap_mig_init()
  migration: Take migration object refcount earlier for threads
  migration: Deprecate query-migrationthreads command
  migration/dirtyrate: Silence warning about strcpy() on OpenBSD
  tests/migration: Add case for periodic ramblock dirty sync
  migration: Support periodic RAMBlock dirty bitmap sync
  migration: Remove "rs" parameter in migration_bitmap_sync_precopy
  migration: Move cpu-throttle.c from system to migration
  migration: Stop CPU throttling conditionally
  accel/tcg/icount-common: Remove the reference to the unused header file
  migration: Ensure vmstate_save() sets errp
  migration: Put thread names together with macros
  migration: Cleanup migrate_fd_cleanup() on accessing to_dst_file

Signed-off-by: Peter Maydell <[email protected]>

Author: pm215

accel/tcg/icount-common.c

@@ -36,7 +36,6 @@
 #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"
 
 /*

docs/about/deprecated.rst

@@ -147,6 +147,14 @@ options are removed in favor of using explicit ``blockdev-create`` and
 ``blockdev-add`` calls. See :doc:`/interop/live-block-operations` for
 details.
 
+``query-migrationthreads`` (since 9.2)
+''''''''''''''''''''''''''''''''''''''
+
+To be removed with no replacement, as it reports only a limited set of
+threads (for example, it only reports source side of multifd threads,
+without reporting any destination threads, or non-multifd source threads).
+For debugging purpose, please use ``-name $VM,debug-threads=on`` instead.
+
 Incorrectly typed ``device_add`` arguments (since 6.2)
 ''''''''''''''''''''''''''''''''''''''''''''''''''''''
 

hw/vfio/common.c

@@ -149,7 +149,7 @@ bool vfio_viommu_preset(VFIODevice *vbasedev)
 
 static void vfio_set_migration_error(int ret)
 {
-    if (migration_is_setup_or_active()) {
+    if (migration_is_running()) {
         migration_file_set_error(ret, NULL);
     }
 }

hw/virtio/virtio-mem.c

@@ -188,7 +188,7 @@ static bool virtio_mem_is_busy(void)
      * after plugging them) until we're running on the destination (as we didn't
      * migrate these blocks when they were unplugged).
      */
-    return migration_in_incoming_postcopy() || !migration_is_idle();
+    return migration_in_incoming_postcopy() || migration_is_running();
 }
 
 typedef int (*virtio_mem_range_cb)(VirtIOMEM *vmem, void *arg,

include/migration/misc.h

@@ -39,7 +39,6 @@ void precopy_add_notifier(NotifierWithReturn *n);
 void precopy_remove_notifier(NotifierWithReturn *n);
 int precopy_notify(PrecopyNotifyReason reason, Error **errp);
 
-void ram_mig_init(void);
 void qemu_guest_free_page_hint(void *addr, size_t len);
 bool migrate_ram_is_ignored(RAMBlock *block);
 
@@ -53,11 +52,11 @@ void dump_vmstate_json_to_file(FILE *out_fp);
 /* migration/migration.c */
 void migration_object_init(void);
 void migration_shutdown(void);
-bool migration_is_idle(void);
+
 bool migration_is_active(void);
 bool migration_is_device(void);
+bool migration_is_running(void);
 bool migration_thread_is_self(void);
-bool migration_is_setup_or_active(void);
 
 typedef enum MigrationEventType {
     MIG_EVENT_PRECOPY_SETUP,
@@ -96,7 +95,6 @@ void migration_add_notifier_mode(NotifierWithReturn *notify,
                                  MigrationNotifyFunc func, MigMode mode);
 
 void migration_remove_notifier(NotifierWithReturn *notify);
-bool migration_is_running(void);
 void migration_file_set_error(int ret, Error *err);
 
 /* True if incoming migration entered POSTCOPY_INCOMING_DISCARD */
@@ -108,7 +106,4 @@ bool migration_incoming_postcopy_advised(void);
 /* True if background snapshot is active */
 bool migration_in_bg_snapshot(void);
 
-/* migration/block-dirty-bitmap.c */
-void dirty_bitmap_mig_init(void);
-
 #endif

include/sysemu/cpu-throttle.h

@@ -65,4 +65,18 @@ bool cpu_throttle_active(void);
  */
 int cpu_throttle_get_percentage(void);
 
+/**
+ * cpu_throttle_dirty_sync_timer_tick:
+ *
+ * Dirty sync timer hook.
+ */
+void cpu_throttle_dirty_sync_timer_tick(void *opaque);
+
+/**
+ * cpu_throttle_dirty_sync_timer:
+ *
+ * Start or stop the dirty sync timer.
+ */
+void cpu_throttle_dirty_sync_timer(bool enable);
+
 #endif /* SYSEMU_CPU_THROTTLE_H */

migration/colo.c

@@ -935,7 +935,8 @@ void coroutine_fn colo_incoming_co(void)
     assert(bql_locked());
     assert(migration_incoming_colo_enabled());
 
-    qemu_thread_create(&th, "mig/dst/colo", colo_process_incoming_thread,
+    qemu_thread_create(&th, MIGRATION_THREAD_DST_COLO,
+                       colo_process_incoming_thread,
                        mis, QEMU_THREAD_JOINABLE);
 
     mis->colo_incoming_co = qemu_coroutine_self();

system/cpu-throttle.c renamed to migration/cpu-throttle.c

@@ -28,16 +28,23 @@
 #include "qemu/main-loop.h"
 #include "sysemu/cpus.h"
 #include "sysemu/cpu-throttle.h"
+#include "migration.h"
+#include "migration-stats.h"
 #include "trace.h"
 
 /* vcpu throttling controls */
-static QEMUTimer *throttle_timer;
+static QEMUTimer *throttle_timer, *throttle_dirty_sync_timer;
 static unsigned int throttle_percentage;
+static bool throttle_dirty_sync_timer_active;
+static uint64_t throttle_dirty_sync_count_prev;
 
 #define CPU_THROTTLE_PCT_MIN 1
 #define CPU_THROTTLE_PCT_MAX 99
 #define CPU_THROTTLE_TIMESLICE_NS 10000000
 
+/* Making sure RAMBlock dirty bitmap is synchronized every five seconds */
+#define CPU_THROTTLE_DIRTY_SYNC_TIMESLICE_MS 5000
+
 static void cpu_throttle_thread(CPUState *cpu, run_on_cpu_data opaque)
 {
     double pct;
@@ -112,6 +119,7 @@ void cpu_throttle_set(int new_throttle_pct)
 void cpu_throttle_stop(void)
 {
     qatomic_set(&throttle_percentage, 0);
+    cpu_throttle_dirty_sync_timer(false);
 }
 
 bool cpu_throttle_active(void)
@@ -124,8 +132,68 @@ int cpu_throttle_get_percentage(void)
     return qatomic_read(&throttle_percentage);
 }
 
+void cpu_throttle_dirty_sync_timer_tick(void *opaque)
+{
+    uint64_t sync_cnt = stat64_get(&mig_stats.dirty_sync_count);
+
+    /*
+     * The first iteration copies all memory anyhow and has no
+     * effect on guest performance, therefore omit it to avoid
+     * paying extra for the sync penalty.
+     */
+    if (sync_cnt <= 1) {
+        goto end;
+    }
+
+    if (sync_cnt == throttle_dirty_sync_count_prev) {
+        trace_cpu_throttle_dirty_sync();
+        WITH_RCU_READ_LOCK_GUARD() {
+            migration_bitmap_sync_precopy(false);
+        }
+    }
+
+end:
+    throttle_dirty_sync_count_prev = stat64_get(&mig_stats.dirty_sync_count);
+
+    timer_mod(throttle_dirty_sync_timer,
+        qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT) +
+            CPU_THROTTLE_DIRTY_SYNC_TIMESLICE_MS);
+}
+
+static bool cpu_throttle_dirty_sync_active(void)
+{
+    return qatomic_read(&throttle_dirty_sync_timer_active);
+}
+
+void cpu_throttle_dirty_sync_timer(bool enable)
+{
+    assert(throttle_dirty_sync_timer);
+
+    if (enable) {
+        if (!cpu_throttle_dirty_sync_active()) {
+            /*
+             * Always reset the dirty sync count cache, in case migration
+             * was cancelled once.
+             */
+            throttle_dirty_sync_count_prev = 0;
+            timer_mod(throttle_dirty_sync_timer,
+                qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT) +
+                    CPU_THROTTLE_DIRTY_SYNC_TIMESLICE_MS);
+            qatomic_set(&throttle_dirty_sync_timer_active, 1);
+        }
+    } else {
+        if (cpu_throttle_dirty_sync_active()) {
+            timer_del(throttle_dirty_sync_timer);
+            qatomic_set(&throttle_dirty_sync_timer_active, 0);
+        }
+    }
+}
+
 void cpu_throttle_init(void)
 {
     throttle_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT,
                                   cpu_throttle_timer_tick, NULL);
+    throttle_dirty_sync_timer =
+        timer_new_ms(QEMU_CLOCK_VIRTUAL_RT,
+                     cpu_throttle_dirty_sync_timer_tick, NULL);
 }

migration/dirtyrate.c

@@ -29,6 +29,7 @@
 #include "sysemu/runstate.h"
 #include "exec/memory.h"
 #include "qemu/xxhash.h"
+#include "migration.h"
 
 /*
  * total_dirty_pages is procted by BQL and is used
@@ -436,6 +437,7 @@ static void get_ramblock_dirty_info(RAMBlock *block,
                                     struct DirtyRateConfig *config)
 {
     uint64_t sample_pages_per_gigabytes = config->sample_pages_per_gigabytes;
+    gsize len;
 
     /* Right shift 30 bits to calc ramblock size in GB */
     info->sample_pages_count = (qemu_ram_get_used_length(block) *
@@ -444,7 +446,9 @@ static void get_ramblock_dirty_info(RAMBlock *block,
     info->ramblock_pages = qemu_ram_get_used_length(block) >>
                            qemu_target_page_bits();
     info->ramblock_addr = qemu_ram_get_host_addr(block);
-    strcpy(info->idstr, qemu_ram_get_idstr(block));
+    len = g_strlcpy(info->idstr, qemu_ram_get_idstr(block),
+                    sizeof(info->idstr));
+    g_assert(len < sizeof(info->idstr));
 }
 
 static void free_ramblock_dirty_info(struct RamblockDirtyInfo *infos, int count)
@@ -839,8 +843,9 @@ void qmp_calc_dirty_rate(int64_t calc_time,
 
     init_dirtyrate_stat(config);
 
-    qemu_thread_create(&thread, "get_dirtyrate", get_dirtyrate_thread,
-                       (void *)&config, QEMU_THREAD_DETACHED);
+    qemu_thread_create(&thread, MIGRATION_THREAD_DIRTY_RATE,
+                       get_dirtyrate_thread, (void *)&config,
+                       QEMU_THREAD_DETACHED);
 }
 
 

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',