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David Alan Gilbert" , peterx@redhat.com, Kevin Wolf , Paolo Bonzini , =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , Fabiano Rosas , Hailiang Zhang , Yury Kotov , Vladimir Sementsov-Ogievskiy , Prasad Pandit , Zhang Chen , Li Zhijian , Juraj Marcin , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= , "Maciej S. Szmigiero" Subject: [PATCH RFC 1/9] migration/vfio: Remove BQL implication in vfio_multifd_switchover_start() Date: Wed, 27 Aug 2025 16:59:40 -0400 Message-ID: <20250827205949.364606-2-peterx@redhat.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250827205949.364606-1-peterx@redhat.com> References: <20250827205949.364606-1-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=170.10.133.124; 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_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: 1756328599454124100 We may switch to a BQL-free loadvm model. Be prepared with it. Cc: C=C3=A9dric Le Goater Cc: Maciej S. Szmigiero Signed-off-by: Peter Xu Reviewed-by: Fabiano Rosas --- hw/vfio/migration-multifd.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/hw/vfio/migration-multifd.c b/hw/vfio/migration-multifd.c index e4785031a7..8dc8444f0d 100644 --- a/hw/vfio/migration-multifd.c +++ b/hw/vfio/migration-multifd.c @@ -763,16 +763,21 @@ int vfio_multifd_switchover_start(VFIODevice *vbasede= v) { VFIOMigration *migration =3D vbasedev->migration; VFIOMultifd *multifd =3D migration->multifd; + bool bql_is_locked =3D bql_locked(); =20 assert(multifd); =20 /* The lock order is load_bufs_mutex -> BQL so unlock BQL here first */ - bql_unlock(); + if (bql_is_locked) { + 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(); + if (bql_is_locked) { + bql_lock(); + } =20 qemu_loadvm_start_load_thread(vfio_load_bufs_thread, vbasedev); =20 --=20 2.50.1