If PCI passthrough type is not supported, we should error out rather than continue building the command line. When starting a domain, the type has been already checked by qemuPrepareHostdevPCICheckSupport() before building qemu command line, so the problem doesn't emerge. But when coverting a domain xml without specifying passthrough type explictly to qemu arg, we will get a malformed command line. the xml: <hostdev mode='subsystem' type='pci' managed='yes'> <source> <address domain='0x0001' bus='0x03' slot='0x00' function='0x0'/> </source> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </hostdev> the converted command line: -device ,host=0001:03:00.0,id=hostdev0,bus=pci.0,addr=0x5 After this patch, virsh gives an error message: virsh domxml-to-native qemu-argv /tmp/tmp.xml error: internal error: invalid PCI passthrough type 'default' Signed-off-by: Hu Tao <hutao(a)cn.fujitsu.com&gt; --- src/qemu/qemu_command.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 7f9357c..12d6354 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -4880,7 +4880,7 @@ qemuBuildPCIHostdevDevStr(virDomainDefPtr def, virReportError(VIR_ERR_INTERNAL_ERROR, _("invalid PCI passthrough type '%s'"), virDomainHostdevSubsysPCIBackendTypeToString(backend)); - break; + goto error; } virBufferAddLit(&buf, ",host="); -- 1.8.0