Re: [Qemu-devel] VCPU hotplug on KVM/ARM

[Marc Zyngier]

On 24/07/18 19:35, Maran Wilson wrote:
> It's been a few months since this email thread died off. Has anyone 
> started working on a potential solution that would allow VCPU hotplug on 
> KVM/ARM ? Or is this a project that is still waiting for an owner who 
> has the time and inclination to get started?

This is typically a project for someone who would have this particular
itch to scratch, and who has a demonstrable need for this functionality.

Work wise, it would have to include adding physical CPU hotplug support
to the arm64 kernel as a precondition, before worrying about doing it in
KVM.

For KVM itself, particular area of interests would be:
- Making GICv3 redistributors magically appear in the IPA space
- Live resizing of GICv3 structures
- Dynamic allocation of MPIDR, and mapping with vcpu_id

This should keep someone busy for a good couple of weeks (give or take a
few months).

That being said, I'd rather see support in QEMU first, creating all the
vcpu/redistributors upfront, and signalling the hotplug event via the
virtual firmware. And then post some numbers to show that creating all
the vcpus upfront is not acceptable.

Thanks,

        M.
-- 
Jazz is not dead. It just smells funny...