Re: [PATCH 7/8] qemu: add dbus-vmstate helper migration support
Hi
On Thu, Feb 20, 2020 at 10:04 AM Michal Privoznik <mprivozn(a)redhat.com> wrote:
On 1/14/20 2:46 PM, marcandre.lureau(a)redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau(a)redhat.com>
>
> Helper processes may have their state migrated with QEMU data stream
> thanks to the QEMU "dbus-vmstate".
>
> libvirt maintains the list of helpers to be migrated. The
> "dbus-vmstate" is added when required, and given the list of helper
> Ids that must be migrated, on save & load sides.
>
> See also:
> https://git.qemu.org/?p=qemu.git;a=blob;f=docs/interop/dbus-vmstate.rst
>
> Signed-off-by: Marc-André Lureau <marcandre.lureau(a)redhat.com>
> ---
> src/qemu/qemu_alias.c | 7 +++
> src/qemu/qemu_alias.h | 2 +
> src/qemu/qemu_command.c | 62 +++++++++++++++++++++++++++
> src/qemu/qemu_command.h | 3 ++
> src/qemu/qemu_dbus.c | 14 ++++++
> src/qemu/qemu_dbus.h | 4 ++
> src/qemu/qemu_domain.c | 10 +++++
> src/qemu/qemu_domain.h | 5 +++
> src/qemu/qemu_hotplug.c | 82 ++++++++++++++++++++++++++++++++++++
> src/qemu/qemu_hotplug.h | 8 ++++
> src/qemu/qemu_migration.c | 51 ++++++++++++++++++++++
> src/qemu/qemu_monitor.c | 21 +++++++++
> src/qemu/qemu_monitor.h | 3 ++
> src/qemu/qemu_monitor_json.c | 15 +++++++
> src/qemu/qemu_monitor_json.h | 5 +++
> 15 files changed, 292 insertions(+)
>
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index 71d0bb0879..8c281f3a70 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
> @@ -1125,10 +1125,18 @@ qemuMigrationSrcIsAllowed(virQEMUDriverPtr driver,
> bool remote,
> unsigned int flags)
> {
> + qemuDomainObjPrivatePtr priv = vm->privateData;
> int nsnapshots;
> int pauseReason;
> size_t i;
>
> + if (virStringListLength((const char **)priv->dbusVMStateIds) &&
> + !virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DBUS_VMSTATE)) {
> + virReportError(VIR_ERR_OPERATION_INVALID, "%s",
> + _("cannot migrate this domain without dbus-vmstate
support"));
> + return false;
> + }
> +
This should be done in the if(!OFFLINE) a few lines below. IIUC, vmstate
is runtime thing, and when doing offline migration (e.g. just copying
over disks and XMLs), no qemu is involved and thus no vmstate matters.
Right, thanks
> /* perform these checks only when migrating to remote hosts */
> if (remote) {
> nsnapshots = virDomainSnapshotObjListNum(vm->snapshots, NULL, 0);
Michal