[libvirt] [PATCH] conf: Fix backwards migration of pSeries guests

Recent commits made it so that pci-root controllers for pSeries guests are automatically assigned the spapr-pci-host-bridge model name; however, that prevents guests to migrate to older versions of libvirt which don't know about that model name at all, which at the moment is all of them :) To avoid the issue, just strip the model name from PHBs when formatting the migratable XML; guests that use more than one PHB are not going to be migratable anyway. Signed-off-by: Andrea Bolognani <abologna(a)redhat.com&gt; --- src/conf/domain_conf.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 9320794..21bd7c7 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -21919,7 +21919,20 @@ virDomainControllerDefFormat(virBufferPtr buf, } if (def->type == VIR_DOMAIN_CONTROLLER_TYPE_PCI) { - if (def->opts.pciopts.modelName != VIR_DOMAIN_CONTROLLER_PCI_MODEL_NAME_NONE) { + bool formatModelName = true; + + if (def->opts.pciopts.modelName == VIR_DOMAIN_CONTROLLER_PCI_MODEL_NAME_NONE) + formatModelName = false; + + /* Don't format the model name for PHBs when migrating so that + * guests that only use the default one can be migrated to older + * libvirt version which don't know about PHBs at all */ + if (virDomainControllerIsPCIHostBridge(def) && + flags & VIR_DOMAIN_DEF_FORMAT_MIGRATABLE) { + formatModelName = false; + } + + if (formatModelName) { modelName = virDomainControllerPCIModelNameTypeToString(def->opts.pciopts.modelName); if (!modelName) { virReportError(VIR_ERR_INTERNAL_ERROR, -- 2.7.5