void vgic_v2_populate_lr()

in kvm/vgic/vgic-v2.c [122:198]

• 49 lines of code
• 18 McCabe index (conditional complexity)

void vgic_v2_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr)
{
	u32 val = irq->intid;
	bool allow_pending = true;

	if (irq->active) {
		val |= GICH_LR_ACTIVE_BIT;
		if (vgic_irq_is_sgi(irq->intid))
			val |= irq->active_source << GICH_LR_PHYSID_CPUID_SHIFT;
		if (vgic_irq_is_multi_sgi(irq)) {
			allow_pending = false;
			val |= GICH_LR_EOI;
		}
	}

	if (irq->group)
		val |= GICH_LR_GROUP1;

	if (irq->hw && !vgic_irq_needs_resampling(irq)) {
		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)
			allow_pending = false;
	} else {
		if (irq->config == VGIC_CONFIG_LEVEL) {
			val |= GICH_LR_EOI;

			/*
			 * Software resampling doesn't work very well
			 * if we allow P+A, so let's not do that.
			 */
			if (irq->active)
				allow_pending = false;
		}
	}

	if (allow_pending && irq_is_pending(irq)) {
		val |= GICH_LR_PENDING_BIT;

		if (irq->config == VGIC_CONFIG_EDGE)
			irq->pending_latch = false;

		if (vgic_irq_is_sgi(irq->intid)) {
			u32 src = ffs(irq->source);

			if (WARN_RATELIMIT(!src, "No SGI source for INTID %d\n",
					   irq->intid))
				return;

			val |= (src - 1) << GICH_LR_PHYSID_CPUID_SHIFT;
			irq->source &= ~(1 << (src - 1));
			if (irq->source) {
				irq->pending_latch = true;
				val |= GICH_LR_EOI;
			}
		}
	}

	/*
	 * Level-triggered mapped IRQs are special because we only observe
	 * rising edges as input to the VGIC.  We therefore lower the line
	 * level here, so that we can take new virtual IRQs.  See
	 * vgic_v2_fold_lr_state for more info.
	 */
	if (vgic_irq_is_mapped_level(irq) && (val & GICH_LR_PENDING_BIT))
		irq->line_level = false;

	/* The GICv2 LR only holds five bits of priority. */
	val |= (irq->priority >> 3) << GICH_LR_PRIORITY_SHIFT;

	vcpu->arch.vgic_cpu.vgic_v2.vgic_lr[lr] = val;
}