[PATCH 09/15] KVM: arm64: vgic-v5: align priority comparison with other GICs

[Marc Zyngier]

The way the effective priority mask is computed, and then compared
to the priority of an interrupt to decide whether to wake-up or not,
is slightly odd, and breaks at the limits.

This could result in spurious wake-ups that are undesirable.

Adopt the GICv[23] logic instead, which checks that the priority value
is strictly lower than the mask.

Fixes: 933e5288fa971 ("KVM: arm64: gic-v5: Check for pending PPIs")
Link: https://sashiko.dev/#/patchset/20260319154937.3619520-1-sascha.bischoff%40arm.com
Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kvm/vgic/vgic-v5.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-v5.c b/arch/arm64/kvm/vgic/vgic-v5.c
index 0f269321ece4b..75372bbfb6a6a 100644
--- a/arch/arm64/kvm/vgic/vgic-v5.c
+++ b/arch/arm64/kvm/vgic/vgic-v5.c
@@ -238,7 +238,7 @@ static u32 vgic_v5_get_effective_priority_mask(struct kvm_vcpu *vcpu)
 	 */
 	priority_mask = FIELD_GET(FEAT_GCIE_ICH_VMCR_EL2_VPMR, cpu_if->vgic_vmcr);
 
-	return min(highest_ap, priority_mask + 1);
+	return min(highest_ap, priority_mask);
 }
 
 /*
@@ -367,7 +367,7 @@ bool vgic_v5_has_pending_ppi(struct kvm_vcpu *vcpu)
 
 		scoped_guard(raw_spinlock_irqsave, &irq->irq_lock)
 			has_pending = (irq->enabled && irq_is_pending(irq) &&
-				       irq->priority <= priority_mask);
+				       irq->priority < priority_mask);
 
 		vgic_put_irq(vcpu->kvm, irq);
 
-- 
2.47.3