@@ -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 */
@@ -1097,6 +1130,33 @@ static void fill_source_migration_info(MigrationInfo *info)
info->status = s->state;
}
+#ifdef CONFIG_LINUX
+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;
+}
+#endif /* CONFIG_LINUX */
+
/**
* @migration_caps_check - check capability validity
*
@@ -1158,6 +1218,45 @@ static bool migrate_caps_check(bool *cap_list,
}
}
+ if (cap_list[MIGRATION_CAPABILITY_BACKGROUND_SNAPSHOT]) {
+#ifdef CONFIG_LINUX
+ 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;
+ }
+ }
+#else
+ error_setg(errp,
+ "Background-snapshot is not supported on non-Linux hosts");
+ return false;
+#endif
+ }
+
return true;
}
@@ -2499,6 +2598,15 @@ 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
@@ -3792,6 +3900,8 @@ 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(),
};
@@ -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,
@@ -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,
@@ -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
@@ -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: