Re: [PATCH v2 5/8] KVM: arm/arm64: vgic: Handle mapped level sensitive SPIs

Christoffer Dall
2017-07-21T12:10:46Z

On Thu, Jun 15, 2017 at 02:52:37PM +0200, Eric Auger wrote:
> Currently, the line level of unmapped level sensitive SPIs is
> toggled down by the maintenance IRQ handler/resamplefd mechanism.
>
> As mapped SPI completion is not trapped, we cannot rely on this
> mechanism and the line level needs to be observed at distributor
> level instead.
>
> This patch handles the physical IRQ case in vgic_validate_injection
> and get the line level of a mapped SPI at distributor level.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>
> ---
>
> v1 -> v2:
> - renamed is_unshared_mapped into is_mapped_spi
> - changes to kvm_vgic_map_phys_irq moved in the previous patch
> - make vgic_validate_injection more readable
> - reword the commit message
> ---
> virt/kvm/arm/vgic/vgic.c | 16 ++++++++++++++--
> virt/kvm/arm/vgic/vgic.h | 7 ++++++-
> 2 files changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index 075f073..2e35ac7 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -139,6 +139,17 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
> kfree(irq);
> }
>
> +bool irq_line_level(struct vgic_irq *irq)
> +{
> + bool line_level = irq->line_level;
> +
> + if (unlikely(is_mapped_spi(irq)))
> + WARN_ON(irq_get_irqchip_state(irq->host_irq,
> + IRQCHIP_STATE_PENDING,
> + &line_level));
> + return line_level;
> +}
> +
> /**
> * kvm_vgic_target_oracle - compute the target vcpu for an irq
> *
> @@ -236,13 +247,14 @@ static void vgic_sort_ap_list(struct kvm_vcpu *vcpu)
>
> /*
> * Only valid injection if changing level for level-triggered IRQs or for a
> - * rising edge.
> + * rising edge. Injection of virtual interrupts associated to physical
> + * interrupts always is valid.

why? I don't remember this now, and that means I probably won't in the
future either.

When I look at this now, I'm thinking, if we're not going to change
anything, why proceed beyond validate injection?

> */
> static bool vgic_validate_injection(struct vgic_irq *irq, bool level)
> {
> switch (irq->config) {
> case VGIC_CONFIG_LEVEL:
> - return irq->line_level != level;
> + return (irq->line_level != level || unlikely(is_mapped_spi(irq)));
> case VGIC_CONFIG_EDGE:
> return level;
> }
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index bba7fa2..da254ae 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -96,14 +96,19 @@
> /* we only support 64 kB translation table page size */
> #define KVM_ITS_L1E_ADDR_MASK GENMASK_ULL(51, 16)
>
> +bool irq_line_level(struct vgic_irq *irq);
> +
> static inline bool irq_is_pending(struct vgic_irq *irq)
> {
> if (irq->config == VGIC_CONFIG_EDGE)
> return irq->pending_latch;
> else
> - return irq->pending_latch || irq->line_level;
> + return irq->pending_latch || irq_line_level(irq);
> }
>
> +#define is_mapped_spi(i) \
> +((i)->hw && (i)->intid >= VGIC_NR_PRIVATE_IRQS && (i)->intid < 1020)
> +

nit: why is this not a static inline ?

> /*
> * This struct provides an intermediate representation of the fields contained
> * in the GICH_VMCR and ICH_VMCR registers, such that code exporting the GIC
> --
> 2.5.5
>

Thanks,
-Christoffer