Re: [libvirt] [RFC] kvm: x86: export vCPU halted state to sysfs

On 02.02.2018 21:41, Eduardo Habkost wrote: > On Fri, Feb 02, 2018 at 03:19:45PM -0500, Luiz Capitulino wrote: >> On Fri, 2 Feb 2018 18:09:12 -0200 >> Eduardo Habkost <ehabkost(a)redhat.com&gt; wrote: > [...] >>> Your plan above covers what will happen when using newer QEMU >>> versions, but libvirt still needs to work sanely if running QEMU >>> 2.11. My suggestion is that libvirt do not run query-cpus to ask >>> for the "halted" field on any architecture except s390. >> >> My current plan is to ask libvirt to completely remove query-cpus >> usage, independent of the arch and use the new command instead. > > This would be a regression for people running QEMU 2.11 on s390. > > (But maybe it would be an acceptable regression? Viktor, what do > you think? Are there production releases of management systems > that already rely on vcpu.<n>.halted?) > Unfortunately, there's code out there looking at vcpu.<n>.halted. I've informed the product team about the issue. If we drop/deprecate vcpu.<n>.halted from the domain statistics, this should be done for all arches, if there's a replacement mechanism (i.e. new VCPU states). As a stop-gap measure we can make the call arch-dependent until the new stuff is in place.

BTW: libvirt cannot eliminate query-cpus entirely because initial CPU topology and changes due to hotplug must be queried.