[pve-devel] [PATCH qemu-server v2 2/2] migration: conntrack: avoid crash when dbus-vmstate object cannot be added (quickly enough)

[Fiona Ebner <f.ebner@proxmox.com>]

As reported in the community forum [0], it might happen that the
dbus-vmstate object is not added (quickly enough) to the target QEMU
instance, before the migration state is loaded. This would result in
a crash of the target instance:

> kvm: Unknown savevm section or instance 'dbus-vmstate/dbus-vmstate'
> 0. Make sure that your current VM setup matches your saved VM setup,
> including any hotplugged devices
> kvm: load of migration failed: Invalid argument

This is after the configuration is already moved and thus there also
is no source instance running anymore.

Change the type of the 'pve-dbus-vmstate@' service to 'notify', so
that starting the service returns success only after the
'dbus-vmstate' object has been added to the QEMU instance.

[0]: https://forum.proxmox.com/threads/172588/

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---

Dependency bump qemu-server -> pve-common needed!

Changes in v2:
* Different approach, make the service type=notify instead of waiting
  in a sleep+check-loop until the object shows up via QMP 'qom-list'.

 src/usr/dbus-vmstate              | 3 +++
 src/usr/pve-dbus-vmstate@.service | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/usr/dbus-vmstate b/src/usr/dbus-vmstate
index ac6f8cfb..b2baa840 100755
--- a/src/usr/dbus-vmstate
+++ b/src/usr/dbus-vmstate
@@ -15,6 +15,7 @@ use Net::DBus::Reactor;
 use PVE::QemuServer::Helpers;
 use PVE::QemuServer::QMPHelpers qw(qemu_objectadd qemu_objectdel);
 use PVE::SafeSyslog;
+use PVE::Systemd;
 use PVE::Tools;
 
 use base qw(Net::DBus::Object);
@@ -165,4 +166,6 @@ qemu_objectadd($vmid, 'pve-vmstate', 'dbus-vmstate',
     'id-list' => "pve-vmstate-$vmid",
 );
 
+PVE::Systemd::sd_notify(0, "READY=1\n");
+
 Net::DBus::Reactor->main()->run();
diff --git a/src/usr/pve-dbus-vmstate@.service b/src/usr/pve-dbus-vmstate@.service
index 56b4e285..616f6979 100644
--- a/src/usr/pve-dbus-vmstate@.service
+++ b/src/usr/pve-dbus-vmstate@.service
@@ -6,5 +6,5 @@ PartOf=%i.scope
 
 [Service]
 Slice=qemu.slice
-Type=simple
+Type=notify
 ExecStart=/usr/libexec/qemu-server/dbus-vmstate %i
-- 
2.47.3



_______________________________________________
pve-devel mailing list
pve-devel@lists.proxmox.com
https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel