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Wed, 22 Oct 2025 12:26:37 -0700 (PDT) X-Google-Smtp-Source: AGHT+IE+7+PkJ8yuFjcIgOIzPsP1vhB0nMTTXKNBqSVlLqqnJXccpPbF8tX8sCpxXNiqLG9IqdlLEA== X-Received: by 2002:ac8:7f50:0:b0:4e8:999b:70a9 with SMTP id d75a77b69052e-4e89d4123dfmr243436591cf.72.1761161196686; Wed, 22 Oct 2025 12:26:36 -0700 (PDT) From: Peter Xu To: qemu-devel@nongnu.org Cc: Li Zhijian , Hailiang Zhang , Kevin Wolf , Vladimir Sementsov-Ogievskiy , peterx@redhat.com, =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , Fabiano Rosas , Zhang Chen , "Dr . David Alan Gilbert" , Prasad Pandit , Paolo Bonzini , Yury Kotov , Juraj Marcin , "Maciej S. Szmigiero" , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= Subject: [PATCH 13/13] migration/vfio: Drop BQL dependency for loadvm SWITCHOVER_START Date: Wed, 22 Oct 2025 15:26:12 -0400 Message-ID: <20251022192612.2737648-14-peterx@redhat.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20251022192612.2737648-1-peterx@redhat.com> References: <20251022192612.2737648-1-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=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-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1761161248910154100 That was there only because we used to do loadvm in a coroutine on the main thread with BQL held, while there was a locking order issue. Now make the API to not depend on BQL anymore. Instead making sure we don't take BQL invoking switchover_start() hooks. Cc: Maciej S. Szmigiero Cc: C=C3=A9dric Le Goater Signed-off-by: Peter Xu --- hw/vfio/migration-multifd.c | 3 --- migration/savevm.c | 3 +-- 2 files changed, 1 insertion(+), 5 deletions(-) diff --git a/hw/vfio/migration-multifd.c b/hw/vfio/migration-multifd.c index e4785031a7..c824f30fb0 100644 --- a/hw/vfio/migration-multifd.c +++ b/hw/vfio/migration-multifd.c @@ -766,13 +766,10 @@ int vfio_multifd_switchover_start(VFIODevice *vbasede= v) =20 assert(multifd); =20 - /* The lock order is load_bufs_mutex -> BQL so unlock BQL here first */ - bql_unlock(); WITH_QEMU_LOCK_GUARD(&multifd->load_bufs_mutex) { assert(!multifd->load_bufs_thread_running); multifd->load_bufs_thread_running =3D true; } - bql_lock(); =20 qemu_loadvm_start_load_thread(vfio_load_bufs_thread, vbasedev); =20 diff --git a/migration/savevm.c b/migration/savevm.c index 16fae635c0..f67b97c9ab 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -2648,8 +2648,7 @@ static int loadvm_process_command(QEMUFile *f, bool b= ql_held, Error **errp) return loadvm_process_enable_colo(mis, errp); =20 case MIG_CMD_SWITCHOVER_START: - WITH_BQL_HELD(bql_held) { - /* TODO: drop the BQL dependency */ + WITH_BQL_RELEASED(bql_held) { ret =3D loadvm_postcopy_handle_switchover_start(errp); } return ret; --=20 2.50.1