[PATCH v3 0/2] KVM: ARM: Enable vtimers with user space gic

[Paolo Bonzini]

On 16/09/2016 14:44, Alexander Graf wrote:
> 
>> On 16 Sep 2016, at 14:40, Paolo Bonzini <pbonzini at redhat.com>
>> wrote:
>> 
>> 
>> 
>> On 16/09/2016 14:29, Christoffer Dall wrote:
>>>> It may be useful for migrating a gicv2 VM to a gicv3 host
>>>> without gicv2 emulation as well.
>>> 
>>> I don't see why you'd do this; the VGIC hardware can perfectly
>>> well be used for nesting as well, and this works rather well.
>> 
>> Can GICv3 emulate GICv2 in a guest?
> 
> It depends on the gicv3 configuration. As an SOC vendor you can
> either enable gicv2 compatibility or disable it. ThunderX for example
> is gicv3 only.

And QEMU complains on startup and exits, I hope.

I am not too optimistic about having migration from kernel GIC to
userspace GIC, honestly.  But GICv2 emulation on GICv3-only hosts is a
very reasonable thing to want, if only for testing/debugging purposes.

Paolo