diff options
| -rw-r--r-- | hw/core/machine.c | 1 | ||||
| -rw-r--r-- | migration/migration.c | 10 | ||||
| -rw-r--r-- | migration/migration.h | 34 | ||||
| -rw-r--r-- | migration/postcopy-ram.c | 20 |
4 files changed, 57 insertions, 8 deletions
diff --git a/hw/core/machine.c b/hw/core/machine.c index 45e3d24fdc..cd13b8b0a3 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -42,6 +42,7 @@ GlobalProperty hw_compat_7_2[] = { { "e1000e", "migrate-timadj", "off" }, { "virtio-mem", "x-early-migration", "false" }, + { "migration", "x-preempt-pre-7-2", "true" }, }; const size_t hw_compat_7_2_len = G_N_ELEMENTS(hw_compat_7_2); diff --git a/migration/migration.c b/migration/migration.c index ae2025d9d8..37fc4fb3e2 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -3464,8 +3464,12 @@ static void migration_completion(MigrationState *s) qemu_savevm_state_complete_postcopy(s->to_dst_file); qemu_mutex_unlock_iothread(); - /* Shutdown the postcopy fast path thread */ - if (migrate_postcopy_preempt()) { + /* + * Shutdown the postcopy fast path thread. This is only needed + * when dest QEMU binary is old (7.1/7.2). QEMU 8.0+ doesn't need + * this. + */ + if (migrate_postcopy_preempt() && s->preempt_pre_7_2) { postcopy_preempt_shutdown_file(s); } @@ -4443,6 +4447,8 @@ static Property migration_properties[] = { decompress_error_check, true), DEFINE_PROP_UINT8("x-clear-bitmap-shift", MigrationState, clear_bitmap_shift, CLEAR_BITMAP_SHIFT_DEFAULT), + DEFINE_PROP_BOOL("x-preempt-pre-7-2", MigrationState, + preempt_pre_7_2, false), /* Migration parameters */ DEFINE_PROP_UINT8("x-compress-level", MigrationState, diff --git a/migration/migration.h b/migration/migration.h index 2da2f8a164..67baba2184 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -65,6 +65,12 @@ typedef struct { bool all_zero; } PostcopyTmpPage; +typedef enum { + PREEMPT_THREAD_NONE = 0, + PREEMPT_THREAD_CREATED, + PREEMPT_THREAD_QUIT, +} PreemptThreadStatus; + /* State for the incoming migration */ struct MigrationIncomingState { QEMUFile *from_src_file; @@ -124,7 +130,12 @@ struct MigrationIncomingState { QemuSemaphore postcopy_qemufile_dst_done; /* Postcopy priority thread is used to receive postcopy requested pages */ QemuThread postcopy_prio_thread; - bool postcopy_prio_thread_created; + /* + * Always set by the main vm load thread only, but can be read by the + * postcopy preempt thread. "volatile" makes sure all reads will be + * uptodate across cores. + */ + volatile PreemptThreadStatus preempt_thread_status; /* * Used to sync between the ram load main thread and the fast ram load * thread. It protects postcopy_qemufile_dst, which is the postcopy @@ -364,6 +375,27 @@ struct MigrationState { * do not trigger spurious decompression errors. */ bool decompress_error_check; + /* + * This variable only affects behavior when postcopy preempt mode is + * enabled. + * + * When set: + * + * - postcopy preempt src QEMU instance will generate an EOS message at + * the end of migration to shut the preempt channel on dest side. + * + * When clear: + * + * - postcopy preempt src QEMU instance will _not_ generate an EOS + * message at the end of migration, the dest qemu will shutdown the + * channel itself. + * + * NOTE: See message-id <ZBoShWArKDPpX/D7@work-vm> on qemu-devel + * mailing list for more information on the possible race. Everyone + * should probably just keep this value untouched after set by the + * machine type (or the default). + */ + bool preempt_pre_7_2; /* * This decides the size of guest memory chunk that will be used diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index 41c0713650..263bab75ec 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -568,9 +568,14 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis) { trace_postcopy_ram_incoming_cleanup_entry(); - if (mis->postcopy_prio_thread_created) { + if (mis->preempt_thread_status == PREEMPT_THREAD_CREATED) { + /* Notify the fast load thread to quit */ + mis->preempt_thread_status = PREEMPT_THREAD_QUIT; + if (mis->postcopy_qemufile_dst) { + qemu_file_shutdown(mis->postcopy_qemufile_dst); + } qemu_thread_join(&mis->postcopy_prio_thread); - mis->postcopy_prio_thread_created = false; + mis->preempt_thread_status = PREEMPT_THREAD_NONE; } if (mis->have_fault_thread) { @@ -1203,7 +1208,7 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis) */ postcopy_thread_create(mis, &mis->postcopy_prio_thread, "fault-fast", postcopy_preempt_thread, QEMU_THREAD_JOINABLE); - mis->postcopy_prio_thread_created = true; + mis->preempt_thread_status = PREEMPT_THREAD_CREATED; } trace_postcopy_ram_enable_notify(); @@ -1652,6 +1657,11 @@ static void postcopy_pause_ram_fast_load(MigrationIncomingState *mis) trace_postcopy_pause_fast_load_continued(); } +static bool preempt_thread_should_run(MigrationIncomingState *mis) +{ + return mis->preempt_thread_status != PREEMPT_THREAD_QUIT; +} + void *postcopy_preempt_thread(void *opaque) { MigrationIncomingState *mis = opaque; @@ -1671,11 +1681,11 @@ void *postcopy_preempt_thread(void *opaque) /* Sending RAM_SAVE_FLAG_EOS to terminate this thread */ qemu_mutex_lock(&mis->postcopy_prio_thread_mutex); - while (1) { + while (preempt_thread_should_run(mis)) { ret = ram_load_postcopy(mis->postcopy_qemufile_dst, RAM_CHANNEL_POSTCOPY); /* If error happened, go into recovery routine */ - if (ret) { + if (ret && preempt_thread_should_run(mis)) { postcopy_pause_ram_fast_load(mis); } else { /* We're done */ |