linux-kernel - Re: [PATCH v5 11/26] KVM: arm/arm64: GICv4: Handle INT command applied to a VLPI

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Message-ID: <6e12eac9-7b75-2c2c-0c79-d17a3c0d65eb@redhat.com>
Date:   Tue, 7 Nov 2017 21:15:29 +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:     Christoffer Dall <christoffer.dall@...aro.org>,
        Shanker Donthineni <shankerd@...eaurora.org>,
        Mark Rutland <mark.rutland@....com>,
        Shameerali Kolothum Thodi 
        <shameerali.kolothum.thodi@...wei.com>,
        Andre Przywara <Andre.Przywara@....com>,
        Christoffer Dall <cdall@...aro.org>
Subject: Re: [PATCH v5 11/26] KVM: arm/arm64: GICv4: Handle INT command
 applied to a VLPI

Hi Marc,

On 27/10/2017 16:28, Marc Zyngier wrote:
> If the guest issues an INT command targetting a VLPI, let's
> call into the irq_set_irqchip_state() helper to make it pending
> on the physical side.
> 
> This works just as well if userspace decides to inject an interrupt
> using the normal userspace API...
There is also another path:
KVM_SIGNAL_MSI ioctl / kvm_send_userspace_msi / kvm_set_msi /
vgic_its_inject_msi / vgic_its_trigger_msi

I wonder whether we shouldn't prevent the userspace from messing up with
the host irq pending state?

Thanks

Eric
> 
> Acked-by: Christoffer Dall <cdall@...aro.org>
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> ---
>  virt/kvm/arm/vgic/vgic-its.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 89768d2b6a91..b2a678d131d0 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -578,6 +578,10 @@ static int vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
>  	if (err)
>  		return err;
>  
> +	if (irq->hw)
> +		return irq_set_irqchip_state(irq->host_irq,
> +					     IRQCHIP_STATE_PENDING, true);
> +
>  	spin_lock(&irq->irq_lock);
>  	irq->pending_latch = true;
>  	vgic_queue_irq_unlock(kvm, irq);
>