On Wed, 7 Aug 2019 10:53:20 +0100
Alexandru Elisei <alexandru.elisei@xxxxxxx> wrote:
> A HW mapped level sensitive interrupt asserted by a device will not be put
> into the ap_list if it is disabled at the VGIC level. When it is enabled
> again, it will be inserted into the ap_list and written to a list register
> on guest entry regardless of the state of the device.
>
> We could argue that this can also happen on real hardware, when the command
> to enable the interrupt reached the GIC before the device had the chance to
> de-assert the interrupt signal; however, we emulate the distributor and
> redistributors in software and we can do better than that.
>
> Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
> ---
> virt/kvm/arm/vgic/vgic-mmio.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
> index 3ba7278fb533..44efc2ff863f 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio.c
> @@ -113,6 +113,22 @@ void vgic_mmio_write_senable(struct kvm_vcpu *vcpu,
> struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>
> raw_spin_lock_irqsave(&irq->irq_lock, flags);
> + if (vgic_irq_is_mapped_level(irq)) {
> + bool was_high = irq->line_level;
> +
> + /*
> + * We need to update the state of the interrupt because
> + * the guest might have changed the state of the device
> + * while the interrupt was disabled at the VGIC level.
> + */
> + irq->line_level = vgic_get_phys_line_level(irq);
> + /*
> + * Deactivate the physical interrupt so the GIC will let
> + * us know when it is asserted again.
> + */
> + if (!irq->active && was_high && !irq->line_level)
> + vgic_irq_set_phys_active(irq, false);
> + }
> irq->enabled = true;
> vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>
Applied, thanks.
M.
--
Without deviation from the norm, progress is not possible.
