From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marc Zyngier <marc.zyngier@arm.com>
Subject: Re: KVM Live migration with GICv3
Date: Wed, 12 Aug 2015 17:17:25 +0100
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To: Pavel Fedin <p.fedin@samsung.com>, 'Vijay Kilari' <vijay.kilari@gmail.com>
Cc: kvmarm@lists.cs.columbia.edu
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On 11/08/15 16:24, Pavel Fedin wrote:
>  Hello!
> 
>> I mean CPU interface registers GICC* defined for vgicv2 under
>> "vgic_cpu_ranges[]" in
>> virt/kvm/arm/vgic-v2-emul.c needs to be saved and restored for vgicv3 as well.
>> So to  access vgic_cpu_ranges[] for vgicv3, we need to register device
>> for CPU registers space
>> similar to gicv2 in QEMU for gicv3.
> 
> This thing is optional and can be missing. It is for backwards
> compatibility only, it allows to run GICv2 guests on GICv3. You
> should not use this API for accessing system registers.

Even more than that.

The KVM emulation of GICv3 doesn't have *any* GICv2 compatibility. And
that's on purpose. So trying to save the GICC registers should give you
an error, because these registers *do not exist* as far as a guest is
concerned.

If you plan to do anything for GICv3, you should only deal with with the
system register version of the CPU interface.

Thanks,

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