When enabling switchover-ack on qemu from libvirt, the .party value
was set to both source and target; however, qemuMigrationParamsCheck()
only takes that into account to validate that the remote side of the
migration supports the flag if it is marked optional or auto/always on.
In the case of switchover-ack, when enabled on only the dst and not
the src, the migration will fail if the src qemu does not support
switchover-ack, as the dst qemu will issue a switchover-ack msg:
qemu/migration/savevm.c ->
loadvm_process_command ->
migrate_send_rp_switchover_ack(mis) ->
migrate_send_rp_message(mis, MIG_RP_MSG_SWITCHOVER_ACK, 0, NULL)
Since the src qemu doesn't understand messages with header_type ==
MIG_RP_MSG_SWITCHOVER_ACK, qemu will kill the migration with error:
qemu-kvm: RP: Received invalid message 0x0007 length 0x0000
qemu-kvm: Unable to write to socket: Bad file descriptor
Looking at the original commit [1] for optional migration capabilities,
it seems that the spirit of optional handling was to enhance a given
existing capability where possible. Given that switchover-ack
exclusively depends on return-path, adding it as optional to that cap
feels right.
[1] 61e34b08568 ("qemu: Add support for optional migration capabilities")
Fixes: 1cc7737f69e ("qemu: add support for qemu switchover-ack")
Signed-off-by: Jon Kohler <jon@xxxxxxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
Cc: Avihai Horon <avihaih@xxxxxxxxxx>
Cc: Jiri Denemark <jdenemar@xxxxxxxxxx>
Cc: Markus Armbruster <armbru@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: YangHang Liu <yanghliu@xxxxxxxxxx>
---
src/qemu/qemu_migration_params.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/src/qemu/qemu_migration_params.c b/src/qemu/qemu_migration_params.c
index 9593b6ba65..98822012cc 100644
--- a/src/qemu/qemu_migration_params.c
+++ b/src/qemu/qemu_migration_params.c
@@ -210,17 +210,13 @@ static const qemuMigrationParamsFlagMapItem qemuMigrationParamsFlagMap[] = {
{.match = QEMU_MIGRATION_FLAG_FORBIDDEN,
.flag = VIR_MIGRATE_TUNNELLED,
.cap = QEMU_MIGRATION_CAP_RETURN_PATH,
+ .optional = QEMU_MIGRATION_CAP_SWITCHOVER_ACK,
.party = QEMU_MIGRATION_SOURCE | QEMU_MIGRATION_DESTINATION},
{.match = QEMU_MIGRATION_FLAG_REQUIRED,
.flag = VIR_MIGRATE_ZEROCOPY,
.cap = QEMU_MIGRATION_CAP_ZERO_COPY_SEND,
.party = QEMU_MIGRATION_SOURCE},
-
- {.match = QEMU_MIGRATION_FLAG_FORBIDDEN,
- .flag = VIR_MIGRATE_TUNNELLED,
- .cap = QEMU_MIGRATION_CAP_SWITCHOVER_ACK,
- .party = QEMU_MIGRATION_SOURCE | QEMU_MIGRATION_DESTINATION},
};
/* Translation from VIR_MIGRATE_PARAM_* typed parameters to
--
2.43.0
