[libvirt] [PATCH 02/16] Add public APIs for post-copy migration

From: Cristian Klein <cristiklein(a)gmail.com&gt; To use post-copy one has to start the migration with VIR_MIGRATE_POSTCOPY flag and VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY or, while migration is in progress, call virDomainMigrateStartPostCopy() to switch from pre-copy to post-copy. Signed-off-by: Cristian Klein <cristiklein(a)gmail.com&gt; Signed-off-by: Jiri Denemark <jdenemar(a)redhat.com&gt; --- include/libvirt/libvirt-domain.h | 5 ++ src/driver-hypervisor.h | 5 ++ src/libvirt-domain.c | 140 +++++++++++++++++++++++++++++++++++++++ src/libvirt_public.syms | 4 ++ src/remote/remote_driver.c | 1 + src/remote/remote_protocol.x | 13 +++- src/remote_protocol-structs | 5 ++ 7 files changed, 172 insertions(+), 1 deletion(-) diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h index 50342d2..221d1e3 100644 --- a/include/libvirt/libvirt-domain.h +++ b/include/libvirt/libvirt-domain.h @@ -662,6 +662,8 @@ typedef enum { VIR_MIGRATE_ABORT_ON_ERROR = (1 << 12), /* abort migration on I/O errors happened during migration */ VIR_MIGRATE_AUTO_CONVERGE = (1 << 13), /* force convergence */ VIR_MIGRATE_RDMA_PIN_ALL = (1 << 14), /* RDMA memory pinning */ + VIR_MIGRATE_POSTCOPY = (1 << 15), /* enable (but do not start) post-copy migration */ + VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY = (1 << 16), /* switch to post-copy after the first pre-copy iteration */ } virDomainMigrateFlags; @@ -810,6 +812,9 @@ int virDomainMigrateGetMaxSpeed(virDomainPtr domain, unsigned long *bandwidth, unsigned int flags); +int virDomainMigrateStartPostCopy(virDomainPtr domain, + unsigned int flags); + char * virConnectGetDomainCapabilities(virConnectPtr conn, const char *emulatorbin, const char *arch, diff --git a/src/driver-hypervisor.h b/src/driver-hypervisor.h index ae2ec4d..68a7730 100644 --- a/src/driver-hypervisor.h +++ b/src/driver-hypervisor.h @@ -638,6 +638,10 @@ typedef int const char *dom_xml); typedef int +(*virDrvDomainMigrateStartPostCopy)(virDomainPtr domain, + unsigned int flags); + +typedef int (*virDrvConnectIsEncrypted)(virConnectPtr conn); typedef int @@ -1443,6 +1447,7 @@ struct _virHypervisorDriver { virDrvDomainGetFSInfo domainGetFSInfo; virDrvDomainInterfaceAddresses domainInterfaceAddresses; virDrvDomainSetUserPassword domainSetUserPassword; + virDrvDomainMigrateStartPostCopy domainMigrateStartPostCopy; }; diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c index 9491845..a822113 100644 --- a/src/libvirt-domain.c +++ b/src/libvirt-domain.c @@ -3537,6 +3537,9 @@ virDomainMigrateUnmanaged(virDomainPtr domain, * automatically when supported). * VIR_MIGRATE_UNSAFE Force migration even if it is considered unsafe. * VIR_MIGRATE_OFFLINE Migrate offline + * VIR_MIGRATE_POSTCOPY Enable (but do not start) post-copy + * VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY Switch to post-copy after the first + * pre-copy iteration. * * VIR_MIGRATE_TUNNELLED requires that VIR_MIGRATE_PEER2PEER be set. * Applications using the VIR_MIGRATE_PEER2PEER flag will probably @@ -3573,6 +3576,14 @@ virDomainMigrateUnmanaged(virDomainPtr domain, * not support this feature and will return an error if bandwidth * is not 0. * + * Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy + * migration. Without VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag the migration + * will be running normally until virDomainMigrateStartPostCopy is called to + * switch migration into the post-copy mode. When + * VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag is set the switch to post-copy + * mode will happen automatically after the first iteration of pre-copy. + * See virDomainMigrateStartPostCopy for more details about post-copy. + * * To see which features are supported by the current hypervisor, * see virConnectGetCapabilities, /capabilities/host/migration_features. * @@ -3748,6 +3759,9 @@ virDomainMigrate(virDomainPtr domain, * automatically when supported). * VIR_MIGRATE_UNSAFE Force migration even if it is considered unsafe. * VIR_MIGRATE_OFFLINE Migrate offline + * VIR_MIGRATE_POSTCOPY Enable (but do not start) post-copy + * VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY Switch to post-copy after the first + * pre-copy iteration. * * VIR_MIGRATE_TUNNELLED requires that VIR_MIGRATE_PEER2PEER be set. * Applications using the VIR_MIGRATE_PEER2PEER flag will probably @@ -3784,6 +3798,14 @@ virDomainMigrate(virDomainPtr domain, * not support this feature and will return an error if bandwidth * is not 0. * + * Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy + * migration. Without VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag the migration + * will be running normally until virDomainMigrateStartPostCopy is called to + * switch migration into the post-copy mode. When + * VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag is set the switch to post-copy + * mode will happen automatically after the first iteration of pre-copy. + * See virDomainMigrateStartPostCopy for more details about post-copy. + * * To see which features are supported by the current hypervisor, * see virConnectGetCapabilities, /capabilities/host/migration_features. * @@ -3968,6 +3990,14 @@ virDomainMigrate2(virDomainPtr domain, * can use either VIR_MIGRATE_NON_SHARED_DISK or * VIR_MIGRATE_NON_SHARED_INC as they are mutually exclusive. * + * Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy + * migration. Without VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag the migration + * will be running normally until virDomainMigrateStartPostCopy is called to + * switch migration into the post-copy mode. When + * VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag is set the switch to post-copy + * mode will happen automatically after the first iteration of pre-copy. + * See virDomainMigrateStartPostCopy for more details about post-copy. + * * There are many limitations on migration imposed by the underlying * technology - for example it may not be possible to migrate between * different processors even with the same architecture, or between @@ -4208,6 +4238,9 @@ int virDomainMigrateUnmanagedCheckCompat(virDomainPtr domain, * automatically when supported). * VIR_MIGRATE_UNSAFE Force migration even if it is considered unsafe. * VIR_MIGRATE_OFFLINE Migrate offline + * VIR_MIGRATE_POSTCOPY Enable (but do not start) post-copy + * VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY Switch to post-copy after the first + * pre-copy iteration. * * The operation of this API hinges on the VIR_MIGRATE_PEER2PEER flag. * If the VIR_MIGRATE_PEER2PEER flag is NOT set, the duri parameter @@ -4240,6 +4273,14 @@ int virDomainMigrateUnmanagedCheckCompat(virDomainPtr domain, * not support this feature and will return an error if bandwidth * is not 0. * + * Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy + * migration. Without VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag the migration + * will be running normally until virDomainMigrateStartPostCopy is called to + * switch migration into the post-copy mode. When + * VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag is set the switch to post-copy + * mode will happen automatically after the first iteration of pre-copy. + * See virDomainMigrateStartPostCopy for more details about post-copy. + * * To see which features are supported by the current hypervisor, * see virConnectGetCapabilities, /capabilities/host/migration_features. * @@ -4321,6 +4362,9 @@ virDomainMigrateToURI(virDomainPtr domain, * automatically when supported). * VIR_MIGRATE_UNSAFE Force migration even if it is considered unsafe. * VIR_MIGRATE_OFFLINE Migrate offline + * VIR_MIGRATE_POSTCOPY Enable (but do not start) post-copy + * VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY Switch to post-copy after the first + * pre-copy iteration. * * The operation of this API hinges on the VIR_MIGRATE_PEER2PEER flag. * @@ -4366,6 +4410,14 @@ virDomainMigrateToURI(virDomainPtr domain, * not support this feature and will return an error if bandwidth * is not 0. * + * Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy + * migration. Without VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag the migration + * will be running normally until virDomainMigrateStartPostCopy is called to + * switch migration into the post-copy mode. When + * VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag is set the switch to post-copy + * mode will happen automatically after the first iteration of pre-copy. + * See virDomainMigrateStartPostCopy for more details about post-copy. + * * To see which features are supported by the current hypervisor, * see virConnectGetCapabilities, /capabilities/host/migration_features. * @@ -4446,6 +4498,14 @@ virDomainMigrateToURI2(virDomainPtr domain, * can use either VIR_MIGRATE_NON_SHARED_DISK or * VIR_MIGRATE_NON_SHARED_INC as they are mutually exclusive. * + * Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy + * migration. Without VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag the migration + * will be running normally until virDomainMigrateStartPostCopy is called to + * switch migration into the post-copy mode. When + * VIR_MIGRATE_POSTCOPY_AFTER_PRECOPY flag is set the switch to post-copy + * mode will happen automatically after the first iteration of pre-copy. + * See virDomainMigrateStartPostCopy for more details about post-copy. + * * There are many limitations on migration imposed by the underlying * technology - for example it may not be possible to migrate between * different processors even with the same architecture, or between @@ -9163,6 +9223,86 @@ virDomainMigrateGetMaxSpeed(virDomainPtr domain, /** + * virDomainMigrateStartPostCopy: + * @domain: a domain object + * @flags: extra flags; not used yet, so callers should always pass 0 + * + * Starts post-copy migration. This function has to be called while + * migration (initiated with VIR_MIGRATE_POSTCOPY flag) is in progress. + * + * Traditional post-copy migration iteratively walks through guest memory + * pages and migrates those that changed since the previous iteration. The + * iterative phase stops when the number of dirty pages is low enough so that + * the virtual CPUs can be paused, all dirty pages transferred to the + * destination, where the virtual CPUs are unpaused, and all this can happen + * within a predefined downtime period. It's clear that this process may never + * converge if downtime is too short and/or the guest keeps changing a lot of + * memory pages. + * + * When migration is switched to post-copy mode, the virtual CPUs are paused + * immediately, only a minimum set of pages is transferred, and the CPUs are + * unpaused on destination. The source keeps sending all remaining memory pages + * to the destination while the guest is already running there. Whenever the + * guest tries to read a memory page which has not been migrated yet, the + * hypervisor has to tell the source to transfer that page in a priority + * channel. To minimize such page faults, it is a good idea to run at least one + * iteration of pre-copy migration before switching to post-copy. + * + * Post-copy migration is guaranteed to converge since each page is transferred + * at most once no matter how fast it changes. On the other hand once the + * guest is running on the destination host, the migration can no longer be + * rolled back because none of the hosts has complete state. If this happens, + * libvirt will leave the domain paused on both hosts with + * VIR_DOMAIN_PAUSED_POSTCOPY_FAILED reason. It's up to the upper layer to + * decide what to do in such case. + * + * The following domain life cycle events are emitted during post-copy + * migration: + * VIR_DOMAIN_EVENT_SUSPENDED_POSTCOPY (on the source) -- migration entered + * post-copy mode. + * VIR_DOMAIN_EVENT_RESUMED_POSTCOPY (on the destination) -- the guest is + * running on the destination host while some of its memory pages still + * remain on the source host; neither the source nor the destination host + * contain a complete guest state from this point until migration + * finishes. + * VIR_DOMAIN_EVENT_RESUMED_MIGRATED (on the destination), + * VIR_DOMAIN_EVENT_STOPPED_MIGRATED (on the source) -- migration finished + * successfully and the destination host holds a complete guest state. + * VIR_DOMAIN_EVENT_SUSPENDED_POSTCOPY_FAILED (on either side) -- emitted + * when migration fails in post-copy mode and it's unclear whether any + * of the hosts has a complete guest state. + * + * Returns 0 in case of success, -1 otherwise. + */ +int +virDomainMigrateStartPostCopy(virDomainPtr domain, + unsigned int flags) +{ + virConnectPtr conn; + + VIR_DOMAIN_DEBUG(domain); + + virResetLastError(); + + virCheckDomainReturn(domain, -1); + conn = domain->conn; + + virCheckReadOnlyGoto(conn->flags, error); + + if (conn->driver->domainMigrateStartPostCopy) { + if (conn->driver->domainMigrateStartPostCopy(domain, flags) < 0) + goto error; + return 0; + } + + virReportUnsupportedError(); + error: + virDispatchError(conn); + return -1; +} + + +/** * virConnectDomainEventRegisterAny: * @conn: pointer to the connection * @dom: pointer to the domain diff --git a/src/libvirt_public.syms b/src/libvirt_public.syms index dd94191..d98414d 100644 --- a/src/libvirt_public.syms +++ b/src/libvirt_public.syms @@ -725,4 +725,8 @@ LIBVIRT_1.2.19 { virDomainRename; } LIBVIRT_1.2.17; +LIBVIRT_1.3.2 { + virDomainMigrateStartPostCopy; +} LIBVIRT_1.2.19; + # .... define new API here using predicted next version number .... diff --git a/src/remote/remote_driver.c b/src/remote/remote_driver.c index d9d7ec8..f0a81a6 100644 --- a/src/remote/remote_driver.c +++ b/src/remote/remote_driver.c @@ -8462,6 +8462,7 @@ static virHypervisorDriver hypervisor_driver = { .domainInterfaceAddresses = remoteDomainInterfaceAddresses, /* 1.2.14 */ .domainSetUserPassword = remoteDomainSetUserPassword, /* 1.2.16 */ .domainRename = remoteDomainRename, /* 1.2.19 */ + .domainMigrateStartPostCopy = remoteDomainMigrateStartPostCopy, /* 1.3.2 */ }; static virNetworkDriver network_driver = { diff --git a/src/remote/remote_protocol.x b/src/remote/remote_protocol.x index bfdbce7..1e1b301 100644 --- a/src/remote/remote_protocol.x +++ b/src/remote/remote_protocol.x @@ -3228,6 +3228,11 @@ struct remote_domain_event_callback_migration_iteration_msg { int iteration; }; +struct remote_domain_migrate_start_post_copy_args { + remote_nonnull_domain dom; + unsigned int flags; +}; + /*----- Protocol. -----*/ /* Define the program number, protocol version and procedure numbers here. */ @@ -5706,5 +5711,11 @@ enum remote_procedure { * @generate: both * @acl: none */ - REMOTE_PROC_DOMAIN_EVENT_CALLBACK_MIGRATION_ITERATION = 359 + REMOTE_PROC_DOMAIN_EVENT_CALLBACK_MIGRATION_ITERATION = 359, + + /** + * @generate: both + * @acl: domain:migrate + */ + REMOTE_PROC_DOMAIN_MIGRATE_START_POST_COPY = 360 }; diff --git a/src/remote_protocol-structs b/src/remote_protocol-structs index dff54e8..b372f49 100644 --- a/src/remote_protocol-structs +++ b/src/remote_protocol-structs @@ -2697,6 +2697,10 @@ struct remote_domain_event_callback_migration_iteration_msg { remote_nonnull_domain dom; int iteration; }; +struct remote_domain_migrate_start_post_copy_args { + remote_nonnull_domain dom; + u_int flags; +}; enum remote_procedure { REMOTE_PROC_CONNECT_OPEN = 1, REMOTE_PROC_CONNECT_CLOSE = 2, @@ -3057,4 +3061,5 @@ enum remote_procedure { REMOTE_PROC_DOMAIN_SET_USER_PASSWORD = 357, REMOTE_PROC_DOMAIN_RENAME = 358, REMOTE_PROC_DOMAIN_EVENT_CALLBACK_MIGRATION_ITERATION = 359, + REMOTE_PROC_DOMAIN_MIGRATE_START_POST_COPY = 360, }; -- 2.7.0