Re: [PATCH v5 16/26] KVM: arm/arm64: GICv4: Propagate property updates to VLPIs

Marc Zyngier
2017-11-10T08:56:20Z

On 10/11/17 08:37, Christoffer Dall wrote:
> On Wed, Nov 08, 2017 at 03:08:36PM +0000, Marc Zyngier wrote:
>> On 07/11/17 21:28, Auger Eric wrote:
>>> Hi Marc,
>>>
>>> On 27/10/2017 16:28, Marc Zyngier wrote:
>>>> Upon updating a property, we propagate it all the way to the physical
>>>> ITS, and ask for an INV command to be executed there.
>>>>
>>>> Acked-by: Christoffer Dall <cdall@linaro.org>
>>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>>>> ---
>>>> virt/kvm/arm/vgic/vgic-its.c | 3 +++
>>>> 1 file changed, 3 insertions(+)
>>>>
>>>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>>>> index 0b7e648e7a0c..2e77c7c83942 100644
>>>> --- a/virt/kvm/arm/vgic/vgic-its.c
>>>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>>>> @@ -296,6 +296,9 @@ static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
>>>> spin_unlock(&irq->irq_lock);
>>>> }
>>>>
>>>> + if (irq->hw)
>>>> + return its_prop_update_vlpi(irq->host_irq, prop, true);
>>>> +
>>>> return 0;
>>>> }
>>> I am confused by the vgic_queue_irq_unlock() on the "hw" path. Why is it
>>> needed in hw mode?
>>
>> It's not. I guess we could bypass this altogether and take a short cut
>> after having updated the priority and enabled fields.
>>
>
> I can apply this on top of the series as well if you're happy with it:
>
> commit b54fba93b1330803a59ca75f3a5102e22cadc871 (HEAD -> next-gicv4)
> Author: Christoffer Dall <christoffer.dall@linaro.org>
> Date: Fri Nov 10 09:34:54 2017 +0100
>
> KVM: arm/arm64: Don't queue VLPIs on INV/INVALL
>
> Since VLPIs are injected directly by the hardware there's no need to
> mark these as pending in software and queue them on the AP list.
>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index c93ecd4a903b..a3754ec719c4 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -292,11 +292,14 @@ static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
> irq->priority = LPI_PROP_PRIORITY(prop);
> irq->enabled = LPI_PROP_ENABLE_BIT(prop);
>
> - vgic_queue_irq_unlock(kvm, irq, flags);
> - } else {
> - spin_unlock_irqrestore(&irq->irq_lock, flags);
> + if (!irq->hw) {
> + vgic_queue_irq_unlock(kvm, irq, flags);
> + return 0;
> + }
> }
>
> + spin_unlock_irqrestore(&irq->irq_lock, flags);
> +
> if (irq->hw)
> return its_prop_update_vlpi(irq->host_irq, prop, needs_inv);
>

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

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