migration: introduce 'background-snapshot' migration capability

Add new capability to 'qapi/migration.json' schema.
Update migrate_caps_check() to validate enabled capability set
against introduced one. Perform checks for required kernel features
and compatibility with guest memory backends.

Signed-off-by: Andrey Gruzdev <andrey.gruzdev@virtuozzo.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210129101407.103458-2-andrey.gruzdev@virtuozzo.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Andrey Gruzdev 2021-01-29 13:14:03 +03:00 committed by Dr. David Alan Gilbert
parent 1dfafcbd39
commit 6e8c25b4c6
5 changed files with 134 additions and 1 deletions

View file

@ -58,6 +58,7 @@
#include "qemu/queue.h"
#include "multifd.h"
#include "qemu/yank.h"
#include "sysemu/cpus.h"
#ifdef CONFIG_VFIO
#include "hw/vfio/vfio-common.h"
@ -134,6 +135,38 @@ enum mig_rp_message_type {
MIG_RP_MSG_MAX
};
/* Migration capabilities set */
struct MigrateCapsSet {
int size; /* Capability set size */
MigrationCapability caps[]; /* Variadic array of capabilities */
};
typedef struct MigrateCapsSet MigrateCapsSet;
/* Define and initialize MigrateCapsSet */
#define INITIALIZE_MIGRATE_CAPS_SET(_name, ...) \
MigrateCapsSet _name = { \
.size = sizeof((int []) { __VA_ARGS__ }) / sizeof(int), \
.caps = { __VA_ARGS__ } \
}
/* Background-snapshot compatibility check list */
static const
INITIALIZE_MIGRATE_CAPS_SET(check_caps_background_snapshot,
MIGRATION_CAPABILITY_POSTCOPY_RAM,
MIGRATION_CAPABILITY_DIRTY_BITMAPS,
MIGRATION_CAPABILITY_POSTCOPY_BLOCKTIME,
MIGRATION_CAPABILITY_LATE_BLOCK_ACTIVATE,
MIGRATION_CAPABILITY_RETURN_PATH,
MIGRATION_CAPABILITY_MULTIFD,
MIGRATION_CAPABILITY_PAUSE_BEFORE_SWITCHOVER,
MIGRATION_CAPABILITY_AUTO_CONVERGE,
MIGRATION_CAPABILITY_RELEASE_RAM,
MIGRATION_CAPABILITY_RDMA_PIN_ALL,
MIGRATION_CAPABILITY_COMPRESS,
MIGRATION_CAPABILITY_XBZRLE,
MIGRATION_CAPABILITY_X_COLO,
MIGRATION_CAPABILITY_VALIDATE_UUID);
/* When we add fault tolerance, we could have several
migrations at once. For now we don't need to add
dynamic creation of migration */
@ -1089,6 +1122,31 @@ static void fill_source_migration_info(MigrationInfo *info)
info->status = s->state;
}
typedef enum WriteTrackingSupport {
WT_SUPPORT_UNKNOWN = 0,
WT_SUPPORT_ABSENT,
WT_SUPPORT_AVAILABLE,
WT_SUPPORT_COMPATIBLE
} WriteTrackingSupport;
static
WriteTrackingSupport migrate_query_write_tracking(void)
{
/* Check if kernel supports required UFFD features */
if (!ram_write_tracking_available()) {
return WT_SUPPORT_ABSENT;
}
/*
* Check if current memory configuration is
* compatible with required UFFD features.
*/
if (!ram_write_tracking_compatible()) {
return WT_SUPPORT_AVAILABLE;
}
return WT_SUPPORT_COMPATIBLE;
}
/**
* @migration_caps_check - check capability validity
*
@ -1150,6 +1208,39 @@ static bool migrate_caps_check(bool *cap_list,
}
}
if (cap_list[MIGRATION_CAPABILITY_BACKGROUND_SNAPSHOT]) {
WriteTrackingSupport wt_support;
int idx;
/*
* Check if 'background-snapshot' capability is supported by
* host kernel and compatible with guest memory configuration.
*/
wt_support = migrate_query_write_tracking();
if (wt_support < WT_SUPPORT_AVAILABLE) {
error_setg(errp, "Background-snapshot is not supported by host kernel");
return false;
}
if (wt_support < WT_SUPPORT_COMPATIBLE) {
error_setg(errp, "Background-snapshot is not compatible "
"with guest memory configuration");
return false;
}
/*
* Check if there are any migration capabilities
* incompatible with 'background-snapshot'.
*/
for (idx = 0; idx < check_caps_background_snapshot.size; idx++) {
int incomp_cap = check_caps_background_snapshot.caps[idx];
if (cap_list[incomp_cap]) {
error_setg(errp,
"Background-snapshot is not compatible with %s",
MigrationCapability_str(incomp_cap));
return false;
}
}
}
return true;
}
@ -2491,6 +2582,15 @@ bool migrate_use_block_incremental(void)
return s->parameters.block_incremental;
}
bool migrate_background_snapshot(void)
{
MigrationState *s;
s = migrate_get_current();
return s->enabled_capabilities[MIGRATION_CAPABILITY_BACKGROUND_SNAPSHOT];
}
/* migration thread support */
/*
* Something bad happened to the RP stream, mark an error
@ -3784,6 +3884,8 @@ static Property migration_properties[] = {
DEFINE_PROP_MIG_CAP("x-block", MIGRATION_CAPABILITY_BLOCK),
DEFINE_PROP_MIG_CAP("x-return-path", MIGRATION_CAPABILITY_RETURN_PATH),
DEFINE_PROP_MIG_CAP("x-multifd", MIGRATION_CAPABILITY_MULTIFD),
DEFINE_PROP_MIG_CAP("x-background-snapshot",
MIGRATION_CAPABILITY_BACKGROUND_SNAPSHOT),
DEFINE_PROP_END_OF_LIST(),
};

View file

@ -341,6 +341,7 @@ int migrate_compress_wait_thread(void);
int migrate_decompress_threads(void);
bool migrate_use_events(void);
bool migrate_postcopy_blocktime(void);
bool migrate_background_snapshot(void);
/* Sending on the return path - generic and then for each message type */
void migrate_send_rp_shut(MigrationIncomingState *mis,

View file

@ -3788,6 +3788,27 @@ static int ram_resume_prepare(MigrationState *s, void *opaque)
return 0;
}
/* ram_write_tracking_available: check if kernel supports required UFFD features
*
* Returns true if supports, false otherwise
*/
bool ram_write_tracking_available(void)
{
/* TODO: implement */
return false;
}
/* ram_write_tracking_compatible: check if guest configuration is
* compatible with 'write-tracking'
*
* Returns true if compatible, false otherwise
*/
bool ram_write_tracking_compatible(void)
{
/* TODO: implement */
return false;
}
static SaveVMHandlers savevm_ram_handlers = {
.save_setup = ram_save_setup,
.save_live_iterate = ram_save_iterate,

View file

@ -79,4 +79,8 @@ void colo_flush_ram_cache(void);
void colo_release_ram_cache(void);
void colo_incoming_start_dirty_log(void);
/* Background snapshot */
bool ram_write_tracking_available(void);
bool ram_write_tracking_compatible(void);
#endif

View file

@ -442,6 +442,11 @@
# @validate-uuid: Send the UUID of the source to allow the destination
# to ensure it is the same. (since 4.2)
#
# @background-snapshot: If enabled, the migration stream will be a snapshot
# of the VM exactly at the point when the migration
# procedure starts. The VM RAM is saved with running VM.
# (since 6.0)
#
# Since: 1.2
##
{ 'enum': 'MigrationCapability',
@ -449,7 +454,7 @@
'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
'block', 'return-path', 'pause-before-switchover', 'multifd',
'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate',
'x-ignore-shared', 'validate-uuid' ] }
'x-ignore-shared', 'validate-uuid', 'background-snapshot'] }
##
# @MigrationCapabilityStatus: