linux-kernel - Re: [PATCH v5 13/26] KVM: arm/arm64: GICv4: Propagate affinity changes to the physical ITS

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Message-ID: <52c64fa1-f662-2703-53c5-d2024ef12254@redhat.com>
Date:   Tue, 7 Nov 2017 22:01:41 +0100
From:   Auger Eric <eric.auger@...hat.com>
To:     Marc Zyngier <marc.zyngier@....com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Mark Rutland <mark.rutland@....com>,
        Andre Przywara <Andre.Przywara@....com>,
        Shameerali Kolothum Thodi 
        <shameerali.kolothum.thodi@...wei.com>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        Shanker Donthineni <shankerd@...eaurora.org>
Subject: Re: [PATCH v5 13/26] KVM: arm/arm64: GICv4: Propagate affinity
 changes to the physical ITS

Hi Marc,

On 27/10/2017 16:28, Marc Zyngier wrote:
> When the guest issues an affinity change, we need to tell the physical
> ITS that we're now targetting a new vcpu.  This is done by extracting
> the current mapping, updating the target, and reapplying the mapping.
> 
> Reviewed-by: Christoffer Dall <christoffer.dall@...aro.org>
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> ---
>  virt/kvm/arm/vgic/vgic-its.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index c9b1c0967426..42ffb9084bb7 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -337,11 +337,25 @@ static int vgic_copy_lpi_list(struct kvm_vcpu *vcpu, u32 **intid_ptr)
>  
>  static int update_affinity(struct vgic_irq *irq, struct kvm_vcpu *vcpu)
>  {
> +	int ret = 0;
> +
>  	spin_lock(&irq->irq_lock);
>  	irq->target_vcpu = vcpu;
>  	spin_unlock(&irq->irq_lock);
>  
> -	return 0;
> +	if (irq->hw) {
> +		struct its_vlpi_map map;
> +
> +		ret = its_get_vlpi(irq->host_irq, &map);
> +		if (ret)
> +			return ret;
> +
> +		map.vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
> +
> +		ret = its_map_vlpi(irq->host_irq, &map);
Do we check somewhere the virtual LPI ID does not exceed the capacity of
the VPT. I fail to find that in the irq-gic-v3-its.c driver.

Also in case the hw part fails, should we still have the irq->target_cpu
set to the new value. In other words shouldn't we first do the hw block
and upon success set the target_vcpu?

Thanks

Eric
> +	}
> +
> +	return ret;
>  }
>  
>  /*
>