Re: [PATCH v3 39/59] KVM: arm/arm64: GICv4: Add property field and per-VM predicate

Marc Zyngier
2017-08-30T09:46:05Z

On 26/08/17 20:49, Christoffer Dall wrote:
> On Mon, Jul 31, 2017 at 06:26:17PM +0100, Marc Zyngier wrote:
>> Add a new has_gicv4 field in the global VGIC state that indicates
>> whether the HW is GICv4 capable, as a per-VM predicate indicating
>> if there is a possibility for a VM to support direct injection
>> (the above being true and the VM having an ITS).
>>
>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>> ---
>> include/kvm/arm_vgic.h | 3 +++
>> virt/kvm/arm/vgic/vgic-mmio-v3.c | 5 +++++
>> virt/kvm/arm/vgic/vgic.h | 2 ++
>> 3 files changed, 10 insertions(+)
>>
>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
>> index ee8587c8c715..84694b42373a 100644
>> --- a/include/kvm/arm_vgic.h
>> +++ b/include/kvm/arm_vgic.h
>> @@ -73,6 +73,9 @@ struct vgic_global {
>> /* Only needed for the legacy KVM_CREATE_IRQCHIP */
>> bool can_emulate_gicv2;
>>
>> + /* Does have GICv4? */
>
> nit: questionable comment, how about
>
> /* Hardware has GICv4? */
> or
> /* Do we have GICv4? */

Yup, reads much better.

>> + bool has_gicv4;
>> +
>> /* GIC system register CPU interface */
>> struct static_key_false gicv3_cpuif;
>>
>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> index 714fa3933546..74109ca75cc0 100644
>> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> @@ -54,6 +54,11 @@ bool vgic_has_its(struct kvm *kvm)
>> return dist->has_its;
>> }
>>
>> +bool vgic_is_v4_capable(struct kvm *kvm)
>> +{
>> + return kvm_vgic_global_state.has_gicv4 && vgic_has_its(kvm);
>> +}
>> +
>
> uber nit: the naming here is a bit funny, because we won't be presenting
> a GICv4 GIC to the guest, so I'd prefer something like
> vgic_supports_direct_msis() or something like that, but this is
> obviously not a deal breaker.

I like it. It has the advantage of not tying the predicate to a
particular direct injection method, should we one day have a GICv6 (no,
please...).

Thanks,

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