[ubuntu] Known that qemu 4.2 is incompatible with GCP instances?

James Page james.page at canonical.com
Tue Jun 9 13:04:12 UTC 2020

On Tue, Jun 9, 2020 at 1:08 PM James Page <james.page at canonical.com> wrote:

> Hi Neil
> On Tue, Jun 9, 2020 at 11:59 AM Neil Jerram <neil at tigera.io> wrote:
>> I run tests with GCP instances as the OpenStack hypervisors.  Obviously
>> it's better if those can use libvirt_type kvm, i.e. nested virtualization,
>> and this has been possible prior to my current Ussuri upgrade work.
>> With Ussuri on Ubuntu, IIUC, we get qemu 4.2 from cloud-archive:ussuri,
>> but qemu 4.2 has a bug that was fixed by this commit prior to 5.0.0:
>> https://github.com/qemu/qemu/commit/4a910e1f6ab4155ec8b24c49b2585cc486916985
>>     target/i386: do not set unsupported VMX secondary execution controls
>>     Commit 048c951 ("target/i386: work around KVM_GET_MSRS bug for
>>     secondary execution controls") added a workaround for KVM pre-dating
>>     commit 6defc591846d ("KVM: nVMX: include conditional controls in
>> /dev/kvm
>>     KVM_GET_MSRS") which wasn't setting certain available controls. The
>>     workaround uses generic CPUID feature bits to set missing VMX
>> controls. [...]
>> The bug manifests on a GCP instance with nested virtualization enabled
>> [1], because such a GCP instance doesn't support MSR features.  The
>> OpenStack-level symptom is that a VM can't be scheduled onto that GCP
>> instance.
>> Is this a well-known problem?  For CentOS/RHEL, [2] looks similar and
>> maybe fixed, but it's difficult to be sure.
> I could not an existing bug in Ubuntu describing these symptoms - any
> chance you can report a bug here:
>   https://bugs.launchpad.net/ubuntu/+source/qemu/+filebug
> Cheers

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