[PATCH v3 16/55] KVM: arm/arm64: vgic-new: Add IRQ sorting

[Eric Auger]

On 05/06/2016 12:45 PM, Andre Przywara wrote:
> From: Christoffer Dall <christoffer.dall at linaro.org>
> 
> Adds the sorting function to cover the case where you have more IRQs
> to consider than you have LRs. We now consider priorities.
> 
> Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> ---
>  virt/kvm/arm/vgic/vgic.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 57 insertions(+)
> 
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index 92b78a0..4fb20fd 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -16,6 +16,7 @@
>  
>  #include <linux/kvm.h>
>  #include <linux/kvm_host.h>
> +#include <linux/list_sort.h>
>  
>  #include "vgic.h"
>  
> @@ -96,6 +97,62 @@ static struct kvm_vcpu *vgic_target_oracle(struct vgic_irq *irq)
>  }
>  
>  /*
> + * The order of items in the ap_lists defines how we'll pack things in LRs as
> + * well, the first items in the list being the first things populated in the
> + * LRs.
> + *
> + * A hard rule is that active interrupts can never be pushed out of the LRs
> + * (and therefore take priority) since we cannot reliably trap on deactivation
> + * of IRQs and therefore they have to be present in the LRs.
> + *
> + * Otherwise things should be sorted by the priority field and the GIC
> + * hardware support will take care of preemption of priority groups etc.
> + *
> + * Return negative if "a" sorts before "b", 0 to preserve order, and positive
> + * to sort "b" before "a".
> + */
> +static int vgic_irq_cmp(void *priv, struct list_head *a, struct list_head *b)
> +{
> +	struct vgic_irq *irqa = container_of(a, struct vgic_irq, ap_list);
> +	struct vgic_irq *irqb = container_of(b, struct vgic_irq, ap_list);
> +	bool penda, pendb;
> +	int ret;
> +
> +	spin_lock(&irqa->irq_lock);
> +	spin_lock(&irqb->irq_lock);
> +
> +	if (irqa->active || irqb->active) {
> +		ret = (int)irqb->active - (int)irqa->active;
> +		goto out;
> +	}
> +
> +	penda = irqa->enabled && irqa->pending;
> +	pendb = irqb->enabled && irqb->pending;
> +
> +	if (!penda || !pendb) {
> +		ret = (int)pendb - (int)penda;
> +		goto out;
> +	}
> +
> +	/* Both pending and enabled, sort by priority */
> +	ret = irqa->priority - irqb->priority;
> +out:
> +	spin_unlock(&irqb->irq_lock);
> +	spin_unlock(&irqa->irq_lock);
> +	return ret;
> +}
> +
> +/* Must be called with the ap_list_lock held */
> +static void vgic_sort_ap_list(struct kvm_vcpu *vcpu)
> +{
> +	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
> +
> +	DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
> +
> +	list_sort(NULL, &vgic_cpu->ap_list_head, vgic_irq_cmp);
> +}
> +
> +/*
>   * Only valid injection if changing level for level-triggered IRQs or for a
>   * rising edge.
>   */
> 
Reviewed-by: Eric Auger <eric.auger at linaro.org>

Eric