On Mon, Nov 18, 2019 at 18:34:36 +0100, Boris Fiuczynski wrote:
On 11/15/19 4:14 PM, Jiri Denemark wrote:
On Fri, Nov 15, 2019 at 15:55:04 +0100, Christian Borntraeger wrote:
On 15.11.19 15:47, Jiri Denemark wrote:
On Fri, Nov 15, 2019 at 15:12:18 +0100, Boris Fiuczynski wrote:
Just a heads up. After installing libvirt rpms of this branch all my existing kvm s390 domains ended up with
<cpu mode='custom' match='exact' check='none'> <model fallback='forbid'>qemu</model> </cpu>
Newly defined domains without specified cpu do so as well.
Unless the domains are all TCG, it seems your QEMU is too old. You need a fairly recent one which contains commit v4.1.0-1683-gde60a92ea7 (s390x/kvm: Set default cpu model for all machine classes)
I the domains all use KVM and you have new enough QEMU, there might be a bug somewhere. Which should not happen :=)
So shouldnt libvirt fence this rework (add default model) to qemu 4.2 and newer?
Libvirt does all this only if query-machines returns default-cpu-type, which is introduced in 4.2. But since it was introduced earlier, anyone using qemu from git between the two commits will see this behavior. Somewhat similar thing will happen on ppc64, but even with the current master. Everything should be OK once QEMU 4.2.0 final release is used, though (since it will contain all required patches).
Jirka
I tested with a newer version of qemu and it worked as you outlined. After that I also tested with qemu v4.1.0. I was a bit surprised at first that a default host-model cpu was generated since I though it would only be done when the qemu has the commit your specified above. After reading your patch 4 the generation is tied to the cpu-model support in qemu. Since this became available on s390 with qemu v2.8.0 I created an additional test patch just to ensure that we do not lose backwards compatibility.
Oh, are you saying QEMU on s390 returns default-cpu-type in query-machines reply even with v4.1.0 and older? I don't see it in our test replies from anything older then v4.2.0. Anyway, libvirt should not set the default CPU with QEMU 4.1.0 and if it does, I have a bug in my patches :-) qemuDomainDefSetDefaultCPU should not be called at all on QEMU 4.1.0 or older. The check for cpu-model support in this function is an additional check and this support should not be sufficient for the default CPU to be filled in. Jirka