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Szmigiero" , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= Subject: [PULL 39/42] vfio/migration: Multifd device state transfer support - send side Date: Thu, 6 Mar 2025 15:14:15 +0100 Message-ID: <20250306141419.2015340-40-clg@redhat.com> In-Reply-To: <20250306141419.2015340-1-clg@redhat.com> References: <20250306141419.2015340-1-clg@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 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=clg@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_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=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: 1741271061127019100 From: "Maciej S. Szmigiero" Implement the multifd device state transfer via additional per-device thread inside save_live_complete_precopy_thread handler. Switch between doing the data transfer in the new handler and doing it in the old save_state handler depending if VFIO multifd transfer is enabled or not. Signed-off-by: Maciej S. Szmigiero Reviewed-by: C=C3=A9dric Le Goater Link: https://lore.kernel.org/qemu-devel/4d727e2e0435e0022d50004e4740776328= 30e08d.1741124640.git.maciej.szmigiero@oracle.com [ clg: - Reordered savevm_vfio_handlers - Updated save_live_complete_precopy* documentation ] Signed-off-by: C=C3=A9dric Le Goater --- docs/devel/migration/vfio.rst | 19 ++++- hw/vfio/migration-multifd.h | 6 ++ include/hw/vfio/vfio-common.h | 6 ++ hw/vfio/migration-multifd.c | 142 ++++++++++++++++++++++++++++++++++ hw/vfio/migration.c | 22 ++++-- hw/vfio/trace-events | 2 + 6 files changed, 189 insertions(+), 8 deletions(-) diff --git a/docs/devel/migration/vfio.rst b/docs/devel/migration/vfio.rst index d6cf60890c43f2ebf085940a233f8b85a900b6b3..a803a09bc15619cfc46384908d5= 0860ca135d26e 100644 --- a/docs/devel/migration/vfio.rst +++ b/docs/devel/migration/vfio.rst @@ -71,11 +71,23 @@ VFIO implements the device hooks for the iterative appr= oach as follows: reassembles the multifd received data and loads it in-order into the dev= ice. In the non-multifd mode this function is a NOP. =20 -* A ``save_state`` function to save the device config space if it is prese= nt. +* A ``save_state`` function to save the device config space if it is prese= nt + in the non-multifd mode. + In the multifd mode it just emits either a dummy EOS marker. =20 * A ``save_live_complete_precopy`` function that sets the VFIO device in _STOP_COPY state and iteratively copies the data for the VFIO device unt= il the vendor driver indicates that no data remains. + In the multifd mode it just emits a dummy EOS marker. + +* A ``save_live_complete_precopy_thread`` function that in the multifd mode + provides thread handler performing multifd device state transfer. + It sets the VFIO device to _STOP_COPY state, iteratively reads the data + from the VFIO device and queues it for multifd transmission until the ve= ndor + driver indicates that no data remains. + After that, it saves the device config space and queues it for multifd + transfer too. + In the non-multifd mode this thread is a NOP. =20 * A ``load_state`` function that loads the config section and the data sections that are generated by the save functions above. @@ -184,8 +196,11 @@ Live migration save path Then the VFIO device is put in _STOP_COPY state (FINISH_MIGRATE, _ACTIVE, _STOP_COPY) .save_live_complete_precopy() is called for each active device - For the VFIO device, iterate in .save_live_complete_precopy() until + For the VFIO device: in the non-multifd mode iterate in + .save_live_complete_precopy() until pending data is 0 + In the multifd mode this iteration is done in + .save_live_complete_precopy_thread() instead. | (POSTMIGRATE, _COMPLETED, _STOP_COPY) Migraton thread schedules cleanup bottom half and exits diff --git a/hw/vfio/migration-multifd.h b/hw/vfio/migration-multifd.h index f0d28fcef2ea737fc550a34ff266a34848bca67c..a664051eb8ae03bc41cb7f9362a= ce840f41066ff 100644 --- a/hw/vfio/migration-multifd.h +++ b/hw/vfio/migration-multifd.h @@ -23,6 +23,12 @@ bool vfio_multifd_transfer_enabled(VFIODevice *vbasedev); bool vfio_multifd_load_state_buffer(void *opaque, char *data, size_t data_= size, Error **errp); =20 +void vfio_multifd_emit_dummy_eos(VFIODevice *vbasedev, QEMUFile *f); + +bool +vfio_multifd_save_complete_precopy_thread(SaveLiveCompletePrecopyThreadDat= a *d, + Error **errp); + int vfio_multifd_switchover_start(VFIODevice *vbasedev); =20 #endif diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h index 9d72ac1eae8a50e06f32d1c46332c9fd3adddce2..961931d9f457e170f26afabc484= a1e7c39675533 100644 --- a/include/hw/vfio/vfio-common.h +++ b/include/hw/vfio/vfio-common.h @@ -298,6 +298,7 @@ void vfio_mig_add_bytes_transferred(unsigned long val); bool vfio_device_state_is_running(VFIODevice *vbasedev); bool vfio_device_state_is_precopy(VFIODevice *vbasedev); =20 +int vfio_save_device_config_state(QEMUFile *f, void *opaque, Error **errp); int vfio_load_device_config_state(QEMUFile *f, void *opaque); =20 #ifdef CONFIG_LINUX @@ -314,6 +315,11 @@ struct vfio_info_cap_header * vfio_get_device_info_cap(struct vfio_device_info *info, uint16_t id); struct vfio_info_cap_header * vfio_get_cap(void *ptr, uint32_t cap_offset, uint16_t id); + +int vfio_migration_set_state(VFIODevice *vbasedev, + enum vfio_device_mig_state new_state, + enum vfio_device_mig_state recover_state, + Error **errp); #endif =20 bool vfio_migration_realize(VFIODevice *vbasedev, Error **errp); diff --git a/hw/vfio/migration-multifd.c b/hw/vfio/migration-multifd.c index 1d81233c755fec825d94c040ff6cf87eb6551f01..bfb9a72fa4503e2ea00731a2ba5= 28a54d09ed4c5 100644 --- a/hw/vfio/migration-multifd.c +++ b/hw/vfio/migration-multifd.c @@ -496,6 +496,148 @@ bool vfio_multifd_setup(VFIODevice *vbasedev, bool al= loc_multifd, Error **errp) return true; } =20 +void vfio_multifd_emit_dummy_eos(VFIODevice *vbasedev, QEMUFile *f) +{ + assert(vfio_multifd_transfer_enabled(vbasedev)); + + /* + * Emit dummy NOP data on the main migration channel since the actual + * device state transfer is done via multifd channels. + */ + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE); +} + +static bool +vfio_save_complete_precopy_thread_config_state(VFIODevice *vbasedev, + char *idstr, + uint32_t instance_id, + uint32_t idx, + Error **errp) +{ + g_autoptr(QIOChannelBuffer) bioc =3D NULL; + g_autoptr(QEMUFile) f =3D NULL; + int ret; + g_autofree VFIODeviceStatePacket *packet =3D NULL; + size_t packet_len; + + bioc =3D qio_channel_buffer_new(0); + qio_channel_set_name(QIO_CHANNEL(bioc), "vfio-device-config-save"); + + f =3D qemu_file_new_output(QIO_CHANNEL(bioc)); + + if (vfio_save_device_config_state(f, vbasedev, errp)) { + return false; + } + + ret =3D qemu_fflush(f); + if (ret) { + error_setg(errp, "%s: save config state flush failed: %d", + vbasedev->name, ret); + return false; + } + + packet_len =3D sizeof(*packet) + bioc->usage; + packet =3D g_malloc0(packet_len); + packet->version =3D VFIO_DEVICE_STATE_PACKET_VER_CURRENT; + packet->idx =3D idx; + packet->flags =3D VFIO_DEVICE_STATE_CONFIG_STATE; + memcpy(&packet->data, bioc->data, bioc->usage); + + if (!multifd_queue_device_state(idstr, instance_id, + (char *)packet, packet_len)) { + error_setg(errp, "%s: multifd config data queuing failed", + vbasedev->name); + return false; + } + + vfio_mig_add_bytes_transferred(packet_len); + + return true; +} + +/* + * This thread is spawned by the migration core directly via + * .save_live_complete_precopy_thread SaveVMHandler. + * + * It exits after either: + * * completing saving the remaining device state and device config, OR: + * * encountering some error while doing the above, OR: + * * being forcefully aborted by the migration core by + * multifd_device_state_save_thread_should_exit() returning true. + */ +bool +vfio_multifd_save_complete_precopy_thread(SaveLiveCompletePrecopyThreadDat= a *d, + Error **errp) +{ + VFIODevice *vbasedev =3D d->handler_opaque; + VFIOMigration *migration =3D vbasedev->migration; + bool ret =3D false; + g_autofree VFIODeviceStatePacket *packet =3D NULL; + uint32_t idx; + + if (!vfio_multifd_transfer_enabled(vbasedev)) { + /* Nothing to do, vfio_save_complete_precopy() does the transfer. = */ + return true; + } + + trace_vfio_save_complete_precopy_thread_start(vbasedev->name, + d->idstr, d->instance_id= ); + + /* We reach here with device state STOP or STOP_COPY only */ + if (vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_STOP_COPY, + VFIO_DEVICE_STATE_STOP, errp)) { + goto thread_exit; + } + + packet =3D g_malloc0(sizeof(*packet) + migration->data_buffer_size); + packet->version =3D VFIO_DEVICE_STATE_PACKET_VER_CURRENT; + + for (idx =3D 0; ; idx++) { + ssize_t data_size; + size_t packet_size; + + if (multifd_device_state_save_thread_should_exit()) { + error_setg(errp, "operation cancelled"); + goto thread_exit; + } + + data_size =3D read(migration->data_fd, &packet->data, + migration->data_buffer_size); + if (data_size < 0) { + error_setg(errp, "%s: reading state buffer %" PRIu32 " failed:= %d", + vbasedev->name, idx, errno); + goto thread_exit; + } else if (data_size =3D=3D 0) { + break; + } + + packet->idx =3D idx; + packet_size =3D sizeof(*packet) + data_size; + + if (!multifd_queue_device_state(d->idstr, d->instance_id, + (char *)packet, packet_size)) { + error_setg(errp, "%s: multifd data queuing failed", vbasedev->= name); + goto thread_exit; + } + + vfio_mig_add_bytes_transferred(packet_size); + } + + if (!vfio_save_complete_precopy_thread_config_state(vbasedev, + d->idstr, + d->instance_id, + idx, errp)) { + goto thread_exit; + } + + ret =3D true; + +thread_exit: + trace_vfio_save_complete_precopy_thread_end(vbasedev->name, ret); + + return ret; +} + int vfio_multifd_switchover_start(VFIODevice *vbasedev) { VFIOMigration *migration =3D vbasedev->migration; diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c index 2ca3fa08d48667e1c338d3e148023afed7251ac4..416643ddd69ab64c252eadd0770= 2a9d5dad0db47 100644 --- a/hw/vfio/migration.c +++ b/hw/vfio/migration.c @@ -120,10 +120,10 @@ static void vfio_migration_set_device_state(VFIODevic= e *vbasedev, vfio_migration_send_event(vbasedev); } =20 -static int vfio_migration_set_state(VFIODevice *vbasedev, - enum vfio_device_mig_state new_state, - enum vfio_device_mig_state recover_sta= te, - Error **errp) +int vfio_migration_set_state(VFIODevice *vbasedev, + enum vfio_device_mig_state new_state, + enum vfio_device_mig_state recover_state, + Error **errp) { VFIOMigration *migration =3D vbasedev->migration; uint64_t buf[DIV_ROUND_UP(sizeof(struct vfio_device_feature) + @@ -238,8 +238,7 @@ static int vfio_load_buffer(QEMUFile *f, VFIODevice *vb= asedev, return ret; } =20 -static int vfio_save_device_config_state(QEMUFile *f, void *opaque, - Error **errp) +int vfio_save_device_config_state(QEMUFile *f, void *opaque, Error **errp) { VFIODevice *vbasedev =3D opaque; int ret; @@ -638,6 +637,11 @@ static int vfio_save_complete_precopy(QEMUFile *f, voi= d *opaque) int ret; Error *local_err =3D NULL; =20 + if (vfio_multifd_transfer_enabled(vbasedev)) { + vfio_multifd_emit_dummy_eos(vbasedev, f); + return 0; + } + trace_vfio_save_complete_precopy_start(vbasedev->name); =20 /* We reach here with device state STOP or STOP_COPY only */ @@ -669,6 +673,11 @@ static void vfio_save_state(QEMUFile *f, void *opaque) Error *local_err =3D NULL; int ret; =20 + if (vfio_multifd_transfer_enabled(vbasedev)) { + vfio_multifd_emit_dummy_eos(vbasedev, f); + return; + } + ret =3D vfio_save_device_config_state(f, opaque, &local_err); if (ret) { error_prepend(&local_err, @@ -825,6 +834,7 @@ static const SaveVMHandlers savevm_vfio_handlers =3D { */ .load_state_buffer =3D vfio_multifd_load_state_buffer, .switchover_start =3D vfio_switchover_start, + .save_live_complete_precopy_thread =3D vfio_multifd_save_complete_prec= opy_thread, }; =20 /* ---------------------------------------------------------------------- = */ diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events index d6b7e34faa392890aad34173b34fd8c8c9df5e84..9347e3a5f6607ec6907f9b426da= 9ab90553292cf 100644 --- a/hw/vfio/trace-events +++ b/hw/vfio/trace-events @@ -171,6 +171,8 @@ vfio_save_block_precopy_empty_hit(const char *name) " (= %s)" vfio_save_cleanup(const char *name) " (%s)" vfio_save_complete_precopy(const char *name, int ret) " (%s) ret %d" vfio_save_complete_precopy_start(const char *name) " (%s)" +vfio_save_complete_precopy_thread_start(const char *name, const char *idst= r, uint32_t instance_id) " (%s) idstr %s instance %"PRIu32 +vfio_save_complete_precopy_thread_end(const char *name, int ret) " (%s) re= t %d" vfio_save_device_config_state(const char *name) " (%s)" vfio_save_iterate(const char *name, uint64_t precopy_init_size, uint64_t p= recopy_dirty_size) " (%s) precopy initial size %"PRIu64" precopy dirty size= %"PRIu64 vfio_save_iterate_start(const char *name) " (%s)" --=20 2.48.1