Re: [libvirt] [PATCH 05/13] qemu: Auto add pci-root for s390/s390x guests

On Mon, Jun 04, 2018 at 02:05:17PM +0800, Yi Min Zhao wrote: > > >在 2018/6/2 下午10:18, Ján Tomko 写道: >> On Thu, May 24, 2018 at 02:24:30PM +0200, Xiao Feng Ren wrote: >>> From: Yi Min Zhao <zyimin(a)linux.ibm.com&gt; >>> >>> The pci-root depends on zpci capability. So autogenerate pci-root if >>> zpci exists. >>> >>> Signed-off-by: Yi Min Zhao <zyimin(a)linux.ibm.com&gt; >>> Reviewed-by: Boris Fiuczynski <fiuczy(a)linux.vnet.ibm.com&gt; >>> Reviewed-by: Stefan Zimmermann <stzi(a)linux.ibm.com&gt; >>> Reviewed-by: Bjoern Walk <bwalk(a)linux.vnet.ibm.com&gt; >>> --- >>> src/qemu/qemu_domain.c | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c >>> index ee676a2789..05136540aa 100644 >>> --- a/src/qemu/qemu_domain.c >>> +++ b/src/qemu/qemu_domain.c >>> @@ -3068,6 +3068,7 @@ qemuDomainDefAddDefaultDevices(virDomainDefPtr >>> def, >>>     case VIR_ARCH_S390X: >>>         addDefaultUSB = false; >>>         addPanicDevice = true; >>> +        addPCIRoot = virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_ZPCI); >> >> So from a certain QEMU version all the S390 machine types have an >> implicit PCI root? >If zPCI exists, there must be pci root. >> >> Is migration a thing on S390? >I'm not clear with your said. Could you please explain more? >> Well from this code it seems from a certain version, QEMU added a new implicit device for all machine types, without letting libvirt have control over it, which is strange. So if we have a machine started by older libvirt on older QEMU, can we do a live migration to a newer libvirt+QEMU with the zPCI functionality? Or did live migration never work on S390?