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

[Ján Tomko]

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 at linux.ibm.com>
>>>
>>> The pci-root depends on zpci capability. So autogenerate pci-root if
>>> zpci exists.
>>>
>>> Signed-off-by: Yi Min Zhao <zyimin at linux.ibm.com>
>>> Reviewed-by: Boris Fiuczynski <fiuczy at linux.vnet.ibm.com>
>>> Reviewed-by: Stefan Zimmermann <stzi at linux.ibm.com>
>>> Reviewed-by: Bjoern Walk <bwalk at linux.vnet.ibm.com>
>>> ---
>>> 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?

Jano
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