From nobody Thu Apr 3 10:45:39 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1741125988050420.5817322002241; Tue, 4 Mar 2025 14:06:28 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tpaOZ-0000a7-90; Tue, 04 Mar 2025 17:05:47 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tpaOR-0000Nt-A7 for qemu-devel@nongnu.org; Tue, 04 Mar 2025 17:05:42 -0500 Received: from vps-ovh.mhejs.net ([145.239.82.108]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tpaOP-0000wJ-7R for qemu-devel@nongnu.org; Tue, 04 Mar 2025 17:05:39 -0500 Received: from MUA by vps-ovh.mhejs.net with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.98) (envelope-from ) id 1tpaOL-00000000LXp-1rap; Tue, 04 Mar 2025 23:05:33 +0100 From: "Maciej S. Szmigiero" To: Peter Xu , Fabiano Rosas Cc: Alex Williamson , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= , Eric Blake , Markus Armbruster , =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , Avihai Horon , Joao Martins , qemu-devel@nongnu.org Subject: [PATCH v6 09/36] migration: Add thread pool of optional load threads Date: Tue, 4 Mar 2025 23:03:36 +0100 Message-ID: X-Mailer: git-send-email 2.48.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=145.239.82.108; envelope-from=mhej@vps-ovh.mhejs.net; helo=vps-ovh.mhejs.net X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1741125990030019000 Content-Type: text/plain; charset="utf-8" From: "Maciej S. Szmigiero" Some drivers might want to make use of auxiliary helper threads during VM state loading, for example to make sure that their blocking (sync) I/O operations don't block the rest of the migration process. Add a migration core managed thread pool to facilitate this use case. The migration core will wait for these threads to finish before (re)starting the VM at destination. Reviewed-by: Fabiano Rosas Signed-off-by: Maciej S. Szmigiero --- include/migration/misc.h | 3 ++ include/qemu/typedefs.h | 2 + migration/migration.c | 2 +- migration/migration.h | 5 +++ migration/savevm.c | 95 +++++++++++++++++++++++++++++++++++++++- migration/savevm.h | 2 +- 6 files changed, 105 insertions(+), 4 deletions(-) diff --git a/include/migration/misc.h b/include/migration/misc.h index c660be80954a..4c171f4e897e 100644 --- a/include/migration/misc.h +++ b/include/migration/misc.h @@ -45,9 +45,12 @@ bool migrate_ram_is_ignored(RAMBlock *block); /* migration/block.c */ =20 AnnounceParameters *migrate_announce_params(void); + /* migration/savevm.c */ =20 void dump_vmstate_json_to_file(FILE *out_fp); +void qemu_loadvm_start_load_thread(MigrationLoadThread function, + void *opaque); =20 /* migration/migration.c */ void migration_object_init(void); diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h index 3d84efcac47a..fd23ff7771b1 100644 --- a/include/qemu/typedefs.h +++ b/include/qemu/typedefs.h @@ -131,5 +131,7 @@ typedef struct IRQState *qemu_irq; * Function types */ typedef void (*qemu_irq_handler)(void *opaque, int n, int level); +typedef bool (*MigrationLoadThread)(void *opaque, bool *should_quit, + Error **errp); =20 #endif /* QEMU_TYPEDEFS_H */ diff --git a/migration/migration.c b/migration/migration.c index 6b2a8af4231d..e28cebb0a775 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -422,7 +422,7 @@ void migration_incoming_state_destroy(void) * Check proper BQL state here rather than risk possible deadlock late= r. */ assert(bql_locked()); - qemu_loadvm_state_cleanup(); + qemu_loadvm_state_cleanup(mis); =20 if (mis->to_src_file) { /* Tell source that we are done */ diff --git a/migration/migration.h b/migration/migration.h index 7b4278e2a32b..d53f7cad84d8 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -43,6 +43,7 @@ #define MIGRATION_THREAD_DST_PREEMPT "mig/dst/preempt" =20 struct PostcopyBlocktimeContext; +typedef struct ThreadPool ThreadPool; =20 #define MIGRATION_RESUME_ACK_VALUE (1) =20 @@ -187,6 +188,10 @@ struct MigrationIncomingState { Coroutine *colo_incoming_co; QemuSemaphore colo_incoming_sem; =20 + /* Optional load threads pool and its thread exit request flag */ + ThreadPool *load_threads; + bool load_threads_abort; + /* * PostcopyBlocktimeContext to keep information for postcopy * live migration, to calculate vCPU block time diff --git a/migration/savevm.c b/migration/savevm.c index 3e86b572cfa8..1abc365570e3 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -54,6 +54,7 @@ #include "qemu/job.h" #include "qemu/main-loop.h" #include "block/snapshot.h" +#include "block/thread-pool.h" #include "qemu/cutils.h" #include "io/channel-buffer.h" #include "io/channel-file.h" @@ -131,6 +132,35 @@ static struct mig_cmd_args { * generic extendable format with an exception for two old entities. */ =20 +/***********************************************************/ +/* Optional load threads pool support */ + +static void qemu_loadvm_thread_pool_create(MigrationIncomingState *mis) +{ + assert(!mis->load_threads); + mis->load_threads =3D thread_pool_new(); + mis->load_threads_abort =3D false; +} + +static void qemu_loadvm_thread_pool_destroy(MigrationIncomingState *mis) +{ + qatomic_set(&mis->load_threads_abort, true); + + bql_unlock(); /* Load threads might be waiting for BQL */ + g_clear_pointer(&mis->load_threads, thread_pool_free); + bql_lock(); +} + +static bool qemu_loadvm_thread_pool_wait(MigrationState *s, + MigrationIncomingState *mis) +{ + bql_unlock(); /* Let load threads do work requiring BQL */ + thread_pool_wait(mis->load_threads); + bql_lock(); + + return !migrate_has_error(s); +} + /***********************************************************/ /* savevm/loadvm support */ =20 @@ -2783,16 +2813,68 @@ static int qemu_loadvm_state_setup(QEMUFile *f, Err= or **errp) return 0; } =20 -void qemu_loadvm_state_cleanup(void) +struct LoadThreadData { + MigrationLoadThread function; + void *opaque; +}; + +static int qemu_loadvm_load_thread(void *thread_opaque) +{ + struct LoadThreadData *data =3D thread_opaque; + MigrationIncomingState *mis =3D migration_incoming_get_current(); + g_autoptr(Error) local_err =3D NULL; + + if (!data->function(data->opaque, &mis->load_threads_abort, &local_err= )) { + MigrationState *s =3D migrate_get_current(); + + /* + * Can't set load_threads_abort here since processing of main migr= ation + * channel data could still be happening, resulting in launching o= f new + * load threads. + */ + + assert(local_err); + + /* + * In case of multiple load threads failing which thread error + * return we end setting is purely arbitrary. + */ + migrate_set_error(s, local_err); + } + + return 0; +} + +void qemu_loadvm_start_load_thread(MigrationLoadThread function, + void *opaque) +{ + MigrationIncomingState *mis =3D migration_incoming_get_current(); + struct LoadThreadData *data; + + /* We only set it from this thread so it's okay to read it directly */ + assert(!mis->load_threads_abort); + + data =3D g_new(struct LoadThreadData, 1); + data->function =3D function; + data->opaque =3D opaque; + + thread_pool_submit_immediate(mis->load_threads, qemu_loadvm_load_threa= d, + data, g_free); +} + +void qemu_loadvm_state_cleanup(MigrationIncomingState *mis) { SaveStateEntry *se; =20 trace_loadvm_state_cleanup(); + QTAILQ_FOREACH(se, &savevm_state.handlers, entry) { if (se->ops && se->ops->load_cleanup) { se->ops->load_cleanup(se->opaque); } } + + qemu_loadvm_thread_pool_destroy(mis); } =20 /* Return true if we should continue the migration, or false. */ @@ -2943,6 +3025,7 @@ out: =20 int qemu_loadvm_state(QEMUFile *f) { + MigrationState *s =3D migrate_get_current(); MigrationIncomingState *mis =3D migration_incoming_get_current(); Error *local_err =3D NULL; int ret; @@ -2952,6 +3035,8 @@ int qemu_loadvm_state(QEMUFile *f) return -EINVAL; } =20 + qemu_loadvm_thread_pool_create(mis); + ret =3D qemu_loadvm_state_header(f); if (ret) { return ret; @@ -2983,12 +3068,18 @@ int qemu_loadvm_state(QEMUFile *f) =20 /* When reaching here, it must be precopy */ if (ret =3D=3D 0) { - if (migrate_has_error(migrate_get_current())) { + if (migrate_has_error(migrate_get_current()) || + !qemu_loadvm_thread_pool_wait(s, mis)) { ret =3D -EINVAL; } else { ret =3D qemu_file_get_error(f); } } + /* + * Set this flag unconditionally so we'll catch further attempts to + * start additional threads via an appropriate assert() + */ + qatomic_set(&mis->load_threads_abort, true); =20 /* * Try to read in the VMDESC section as well, so that dumping tools th= at diff --git a/migration/savevm.h b/migration/savevm.h index cb58434a9437..138c39a7f9f9 100644 --- a/migration/savevm.h +++ b/migration/savevm.h @@ -64,7 +64,7 @@ void qemu_savevm_live_state(QEMUFile *f); int qemu_save_device_state(QEMUFile *f); =20 int qemu_loadvm_state(QEMUFile *f); -void qemu_loadvm_state_cleanup(void); +void qemu_loadvm_state_cleanup(MigrationIncomingState *mis); int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis); int qemu_load_device_state(QEMUFile *f); int qemu_loadvm_approve_switchover(void);