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[70.52.229.124]) by smtp.gmail.com with ESMTPSA id t35-20020a05622a182300b003e3895903bfsm10777241qtc.8.2023.05.02.15.54.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 May 2023 15:54:40 -0700 (PDT) Date: Tue, 2 May 2023 18:54:38 -0400 From: Peter Xu To: Avihai Horon Cc: qemu-devel@nongnu.org, Alex Williamson , =?utf-8?Q?C=C3=A9dric?= Le Goater , Juan Quintela , Leonardo Bras , Eric Blake , Markus Armbruster , Thomas Huth , Laurent Vivier , Paolo Bonzini , Yishai Hadas , Jason Gunthorpe , Maor Gottlieb , Kirti Wankhede , Tarun Gupta , Joao Martins Subject: Re: [PATCH 2/8] migration: Add precopy initial data handshake Message-ID: References: <20230501140141.11743-1-avihaih@nvidia.com> <20230501140141.11743-3-avihaih@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230501140141.11743-3-avihaih@nvidia.com> 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: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.171, 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, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org (I've left high level comment in cover letter, but still some quick comments I noticed when reading) On Mon, May 01, 2023 at 05:01:35PM +0300, Avihai Horon wrote: > Add precopy initial data handshake between source and destination upon > migration setup. The purpose of the handshake is to notify the > destination that precopy initial data is used and which migration users > (i.e., SaveStateEntry) are going to use it. > > The handshake is done in two levels. First, a general enable command is > sent to notify the destination migration code that precopy initial data > is used. > Then, for each migration user in the source that supports precopy > initial data, an enable command is sent to its counterpart in the > destination: > If both support it, precopy initial data will be used for them. > If source doesn't support it, precopy initial data will not be used for > them. > If source supports it and destination doesn't, migration will be failed. > > To implement it, a new migration command MIG_CMD_INITIAL_DATA_ENABLE is > added, as well as a new SaveVMHandlers handler initial_data_advise. > Calling the handler advises the migration user that precopy initial data > is used and its return value indicates whether precopy initial data is > supported by it. > > Signed-off-by: Avihai Horon > --- > include/migration/register.h | 6 +++ > migration/migration.h | 3 ++ > migration/savevm.h | 1 + > migration/migration.c | 4 ++ > migration/savevm.c | 102 +++++++++++++++++++++++++++++++++++ > migration/trace-events | 2 + > 6 files changed, 118 insertions(+) > > diff --git a/include/migration/register.h b/include/migration/register.h > index a8dfd8fefd..0a73f3883e 100644 > --- a/include/migration/register.h > +++ b/include/migration/register.h > @@ -71,6 +71,12 @@ typedef struct SaveVMHandlers { > int (*load_cleanup)(void *opaque); > /* Called when postcopy migration wants to resume from failure */ > int (*resume_prepare)(MigrationState *s, void *opaque); > + > + /* > + * Advises that precopy initial data was requested to be enabled. Returns > + * true if it's supported or false otherwise. Called both in src and dest. > + */ > + bool (*initial_data_advise)(void *opaque); > } SaveVMHandlers; > > int register_savevm_live(const char *idstr, > diff --git a/migration/migration.h b/migration/migration.h > index 3a918514e7..4f615e9dbc 100644 > --- a/migration/migration.h > +++ b/migration/migration.h > @@ -204,6 +204,9 @@ struct MigrationIncomingState { > * contains valid information. > */ > QemuMutex page_request_mutex; > + > + /* Indicates whether precopy initial data was enabled and should be used */ > + bool initial_data_enabled; > }; > > MigrationIncomingState *migration_incoming_get_current(void); > diff --git a/migration/savevm.h b/migration/savevm.h > index fb636735f0..d47ab4ad18 100644 > --- a/migration/savevm.h > +++ b/migration/savevm.h > @@ -58,6 +58,7 @@ void qemu_savevm_send_postcopy_ram_discard(QEMUFile *f, const char *name, > uint64_t *start_list, > uint64_t *length_list); > void qemu_savevm_send_colo_enable(QEMUFile *f); > +void qemu_savevm_send_initial_data_enable(MigrationState *ms, QEMUFile *f); > void qemu_savevm_live_state(QEMUFile *f); > int qemu_save_device_state(QEMUFile *f); > > diff --git a/migration/migration.c b/migration/migration.c > index abcadbb619..68cdf5b184 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -2964,6 +2964,10 @@ static void *migration_thread(void *opaque) > qemu_savevm_send_colo_enable(s->to_dst_file); > } > > + if (migrate_precopy_initial_data()) { > + qemu_savevm_send_initial_data_enable(s, s->to_dst_file); > + } > + > qemu_savevm_state_setup(s->to_dst_file); > > qemu_savevm_wait_unplug(s, MIGRATION_STATUS_SETUP, > diff --git a/migration/savevm.c b/migration/savevm.c > index a9181b444b..2740defdf0 100644 > --- a/migration/savevm.c > +++ b/migration/savevm.c > @@ -71,6 +71,13 @@ > > const unsigned int postcopy_ram_discard_version; > > +typedef struct { > + uint8_t general_enable; > + uint8_t reserved[7]; > + uint8_t idstr[256]; > + uint32_t instance_id; > +} InitialDataInfo; > + > /* Subcommands for QEMU_VM_COMMAND */ > enum qemu_vm_cmd { > MIG_CMD_INVALID = 0, /* Must be 0 */ > @@ -90,6 +97,8 @@ enum qemu_vm_cmd { > MIG_CMD_ENABLE_COLO, /* Enable COLO */ > MIG_CMD_POSTCOPY_RESUME, /* resume postcopy on dest */ > MIG_CMD_RECV_BITMAP, /* Request for recved bitmap on dst */ > + > + MIG_CMD_INITIAL_DATA_ENABLE, /* Enable precopy initial data in dest */ > MIG_CMD_MAX > }; > > @@ -109,6 +118,8 @@ static struct mig_cmd_args { > [MIG_CMD_POSTCOPY_RESUME] = { .len = 0, .name = "POSTCOPY_RESUME" }, > [MIG_CMD_PACKAGED] = { .len = 4, .name = "PACKAGED" }, > [MIG_CMD_RECV_BITMAP] = { .len = -1, .name = "RECV_BITMAP" }, > + [MIG_CMD_INITIAL_DATA_ENABLE] = { .len = sizeof(InitialDataInfo), > + .name = "INITIAL_DATA_ENABLE" }, > [MIG_CMD_MAX] = { .len = -1, .name = "MAX" }, > }; > > @@ -1036,6 +1047,40 @@ static void qemu_savevm_command_send(QEMUFile *f, > qemu_fflush(f); > } > > +void qemu_savevm_send_initial_data_enable(MigrationState *ms, QEMUFile *f) > +{ > + SaveStateEntry *se; > + InitialDataInfo buf; > + > + /* Enable precopy initial data generally in the migration */ > + memset(&buf, 0, sizeof(buf)); > + buf.general_enable = 1; > + qemu_savevm_command_send(f, MIG_CMD_INITIAL_DATA_ENABLE, sizeof(buf), > + (uint8_t *)&buf); > + trace_savevm_send_initial_data_enable(buf.general_enable, (char *)buf.idstr, > + buf.instance_id); Maybe a generalized helper would be nice here to send one MIG_CMD_INITIAL_DATA_ENABLE packet, then it can be used below too. Here instance_id is multi-bytes, we may want to consider endianess. it seems the common way is use big endian over the wire for qemu migration msgs. > + > + /* Enable precopy initial data for each migration user that supports it */ > + QTAILQ_FOREACH(se, &savevm_state.handlers, entry) { > + if (!se->ops || !se->ops->initial_data_advise) { > + continue; > + } > + > + if (!se->ops->initial_data_advise(se->opaque)) { > + continue; > + } > + > + memset(&buf, 0, sizeof(buf)); > + memcpy(buf.idstr, se->idstr, sizeof(buf.idstr)); > + buf.instance_id = se->instance_id; > + > + qemu_savevm_command_send(f, MIG_CMD_INITIAL_DATA_ENABLE, sizeof(buf), > + (uint8_t *)&buf); > + trace_savevm_send_initial_data_enable( > + buf.general_enable, (char *)buf.idstr, buf.instance_id); > + } > +} > + > void qemu_savevm_send_colo_enable(QEMUFile *f) > { > trace_savevm_send_colo_enable(); > @@ -2314,6 +2359,60 @@ static int loadvm_process_enable_colo(MigrationIncomingState *mis) > return ret; > } > > +static int loadvm_handle_initial_data_enable(MigrationIncomingState *mis) > +{ > + InitialDataInfo buf; > + SaveStateEntry *se; > + ssize_t read_size; > + > + read_size = qemu_get_buffer(mis->from_src_file, (void *)&buf, sizeof(buf)); > + if (read_size != sizeof(buf)) { > + error_report("%s: Could not get data buffer, read_size %ld, len %lu", > + __func__, read_size, sizeof(buf)); > + > + return -EIO; > + } > + > + /* Enable precopy initial data generally in the migration */ > + if (buf.general_enable) { > + mis->initial_data_enabled = true; > + trace_loadvm_handle_initial_data_enable( > + buf.general_enable, (char *)buf.idstr, buf.instance_id); > + > + return 0; > + } > + > + /* Enable precopy initial data for a specific migration user */ > + se = find_se((char *)buf.idstr, buf.instance_id); > + if (!se) { > + error_report("%s: Could not find SaveStateEntry, idstr '%s', " > + "instance_id %" PRIu32, > + __func__, buf.idstr, buf.instance_id); > + > + return -ENOENT; > + } > + > + if (!se->ops || !se->ops->initial_data_advise) { > + error_report("%s: '%s' doesn't have required " > + "initial_data_advise op", > + __func__, buf.idstr); > + > + return -EOPNOTSUPP; > + } > + > + if (!se->ops->initial_data_advise(se->opaque)) { > + error_report("%s: '%s' doesn't support precopy initial data", __func__, > + buf.idstr); > + > + return -EOPNOTSUPP; > + } > + > + trace_loadvm_handle_initial_data_enable(buf.general_enable, > + (char *)buf.idstr, buf.instance_id); > + > + return 0; > +} > + > /* > * Process an incoming 'QEMU_VM_COMMAND' > * 0 just a normal return > @@ -2397,6 +2496,9 @@ static int loadvm_process_command(QEMUFile *f) > > case MIG_CMD_ENABLE_COLO: > return loadvm_process_enable_colo(mis); > + > + case MIG_CMD_INITIAL_DATA_ENABLE: > + return loadvm_handle_initial_data_enable(mis); > } > > return 0; > diff --git a/migration/trace-events b/migration/trace-events > index 92161eeac5..21ae471126 100644 > --- a/migration/trace-events > +++ b/migration/trace-events > @@ -23,6 +23,7 @@ loadvm_postcopy_ram_handle_discard_end(void) "" > loadvm_postcopy_ram_handle_discard_header(const char *ramid, uint16_t len) "%s: %ud" > loadvm_process_command(const char *s, uint16_t len) "com=%s len=%d" > loadvm_process_command_ping(uint32_t val) "0x%x" > +loadvm_handle_initial_data_enable(uint8_t general_enable, const char *idstr, int instance_id) "general_enable=%u, idstr=%s, instance_id=%u" > postcopy_ram_listen_thread_exit(void) "" > postcopy_ram_listen_thread_start(void) "" > qemu_savevm_send_postcopy_advise(void) "" > @@ -38,6 +39,7 @@ savevm_send_postcopy_run(void) "" > savevm_send_postcopy_resume(void) "" > savevm_send_colo_enable(void) "" > savevm_send_recv_bitmap(char *name) "%s" > +savevm_send_initial_data_enable(uint8_t general_enable, const char *idstr, int instance_id) "general_enable=%u, idstr=%s, instance_id=%u" > savevm_state_setup(void) "" > savevm_state_resume_prepare(void) "" > savevm_state_header(void) "" > -- > 2.26.3 > -- Peter Xu