Re: [PATCH 3/5] KVM: arm/arm64: vgic-v2: Do not use Active+Pending state for a HW interrupt

Christoffer Dall
2017-05-02T20:56:35Z

On Tue, May 02, 2017 at 02:30:39PM +0100, Marc Zyngier wrote:
> When an interrupt is injected with the HW bit set (indicating that
> deactivation should be propagated to the physical distributor),
> special care must be taken so that we never mark the corresponding
> LR with the Active+Pending state (as the pending state is kept in
> the physycal distributor).
>
> Cc: stable@vger.kernel.org
> Fixes: 140b086dd197 ("KVM: arm/arm64: vgic-new: Add GICv2 world switch backend")
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

Reviewed-by: Christoffer Dall <cdall@linaro.org>

> ---
> virt/kvm/arm/vgic/vgic-v2.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c
> index a65757aab6d3..504b4bd0d651 100644
> --- a/virt/kvm/arm/vgic/vgic-v2.c
> +++ b/virt/kvm/arm/vgic/vgic-v2.c
> @@ -149,6 +149,13 @@ void vgic_v2_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr)
> if (irq->hw) {
> val |= GICH_LR_HW;
> val |= irq->hwintid << GICH_LR_PHYSID_CPUID_SHIFT;
> + /*
> + * Never set pending+active on a HW interrupt, as the
> + * pending state is kept at the physical distributor
> + * level.
> + */
> + if (irq->active && irq_is_pending(irq))
> + val &= ~GICH_LR_PENDING_BIT;
> } else {
> if (irq->config == VGIC_CONFIG_LEVEL)
> val |= GICH_LR_EOI;
> --
> 2.11.0
>