On 26.11.2024 20:37, Cédric Le Goater wrote:
On 11/17/24 20:20, Maciej S. Szmigiero wrote:
From: "Maciej S. Szmigiero" <maciej.szmigi...@oracle.com>
This QEMU_VM_COMMAND sub-command and its switchover_start SaveVMHandler is
used to mark the switchover point in main migration stream.
It can be used to inform the destination that all pre-switchover main
migration stream data has been sent/received so it can start to process
post-switchover data that it might have received via other migration
channels like the multifd ones.
Add also the relevant MigrationState bit stream compatibility property and
its hw_compat entry.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigi...@oracle.com>
---
hw/core/machine.c | 1 +
include/migration/client-options.h | 4 +++
include/migration/register.h | 12 +++++++++
migration/colo.c | 3 +++
migration/migration-hmp-cmds.c | 2 ++
migration/migration.c | 3 +++
migration/migration.h | 2 ++
migration/options.c | 9 +++++++
migration/savevm.c | 39 ++++++++++++++++++++++++++++++
migration/savevm.h | 1 +
migration/trace-events | 1 +
scripts/analyze-migration.py | 11 +++++++++
12 files changed, 88 insertions(+)
diff --git a/hw/core/machine.c b/hw/core/machine.c
index a35c4a8faecb..ed8d39fd769f 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -38,6 +38,7 @@
GlobalProperty hw_compat_9_1[] = {
{ TYPE_PCI_DEVICE, "x-pcie-ext-tag", "false" },
+ { "migration", "send-switchover-start", "off"},
};
const size_t hw_compat_9_1_len = G_N_ELEMENTS(hw_compat_9_1);
diff --git a/include/migration/client-options.h
b/include/migration/client-options.h
index 59f4b55cf4f7..289c9d776221 100644
--- a/include/migration/client-options.h
+++ b/include/migration/client-options.h
@@ -10,6 +10,10 @@
#ifndef QEMU_MIGRATION_CLIENT_OPTIONS_H
#define QEMU_MIGRATION_CLIENT_OPTIONS_H
+
+/* properties */
+bool migrate_send_switchover_start(void);
+
/* capabilities */
bool migrate_background_snapshot(void);
diff --git a/include/migration/register.h b/include/migration/register.h
index 0b0292738320..ff0faf5f68c8 100644
--- a/include/migration/register.h
+++ b/include/migration/register.h
@@ -279,6 +279,18 @@ typedef struct SaveVMHandlers {
* otherwise
*/
bool (*switchover_ack_needed)(void *opaque);
+
+ /**
+ * @switchover_start
+ *
+ * Notifies that the switchover has started. Called only on
+ * the destination.
+ *
+ * @opaque: data pointer passed to register_savevm_live()
+ *
+ * Returns zero to indicate success and negative for error
+ */
+ int (*switchover_start)(void *opaque);
We don't need an 'Error **' parameter ? Just asking.
This is only called from "loadvm_process_command(QEMUFile *f)",
which does not support "Error" returns.
} SaveVMHandlers;
/**
diff --git a/migration/colo.c b/migration/colo.c
index 9590f281d0f1..a75c2c41b464 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -452,6 +452,9 @@ static int colo_do_checkpoint_transaction(MigrationState *s,
bql_unlock();
goto out;
}
+
+ qemu_savevm_maybe_send_switchover_start(s->to_dst_file);
I would drop '_maybe_' from the name.
I can drop it, but then there will be no hint in this function
name that this sending is conditional on the relevant migration
property (rather than unconditional).
Thanks,
C.
Thanks,
Maciej
