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KVM: arm64: Invert ap_list sorting to push active interrupts out

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Having established that pending interrupts should have priority
to be moved into the LRs over the active interrupts, implement this
in the ap_list sorting.

Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Link: https://msgid.link/20251120172540.2267180-25-maz@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>
This commit is contained in:
Marc Zyngier
2025-11-20 17:25:14 +00:00
committed by Oliver Upton
parent 76b2eda65c
commit 05984ba67e
1 changed files with 12 additions and 15 deletions
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27
arch/arm64/kvm/vgic/vgic.c
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@@ -270,10 +270,7 @@ struct kvm_vcpu *vgic_target_oracle(struct vgic_irq *irq)
* 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.
*
* Pending, non-active interrupts must be placed at the head of the list.
* Otherwise things should be sorted by the priority field and the GIC
* hardware support will take care of preemption of priority groups etc.
*
@@ -298,21 +295,21 @@ static int vgic_irq_cmp(void *priv, const struct list_head *a,
raw_spin_lock(&irqa->irq_lock);
raw_spin_lock_nested(&irqb->irq_lock, SINGLE_DEPTH_NESTING);
if (irqa->active || irqb->active) {
ret = (int)irqb->active - (int)irqa->active;
penda = irqa->enabled && irq_is_pending(irqa) && !irqa->active;
pendb = irqb->enabled && irq_is_pending(irqb) && !irqb->active;
ret = (int)pendb - (int)penda;
if (ret)
goto out;
}
penda = irqa->enabled && irq_is_pending(irqa);
pendb = irqb->enabled && irq_is_pending(irqb);
if (!penda || !pendb) {
ret = (int)pendb - (int)penda;
/* Both pending and enabled, sort by priority (lower number first) */
ret = (int)irqa->priority - (int)irqb->priority;
if (ret)
goto out;
}
/* Both pending and enabled, sort by priority */
ret = irqa->priority - irqb->priority;
/* Finally, HW bit active interrupts have priority over non-HW ones */
ret = (int)irqb->hw - (int)irqa->hw;
out:
raw_spin_unlock(&irqb->irq_lock);
raw_spin_unlock(&irqa->irq_lock);