Subject: [PATCH v4 14/49] KVM: arm64: GICv3: Extract LR computing primitive

From: Marc Zyngier <[email-masked]>
Date: Thu, 20 Nov 2025 17:25:04 +0000

Split vgic_v3_populate_lr() into two, so that we have another
primitive that computes the LR from a vgic_irq, but doesn't
update anything in the shadow structure.

Tested-by: Fuad Tabba <[email-masked]>
Signed-off-by: Marc Zyngier <[email-masked]>
---
 arch/arm64/kvm/vgic/vgic-v3.c | 49 +++++++++++++++++++++++------------
 1 file changed, 32 insertions(+), 17 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c
index 6b7d7b4048f03..bcce7f35a6d67 100644
--- a/arch/arm64/kvm/vgic/vgic-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-v3.c
@@ -107,7 +107,7 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
 }
 
 /* Requires the irq to be locked already */
-void vgic_v3_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr)
+static u64 vgic_v3_compute_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq)
 {
 	u32 model = vcpu->kvm->arch.vgic.vgic_model;
 	u64 val = irq->intid;
@@ -154,6 +154,35 @@ void vgic_v3_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr)
 	if (allow_pending && irq_is_pending(irq)) {
 		val |= ICH_LR_PENDING_BIT;
 
+		if (is_v2_sgi) {
+			u32 src = ffs(irq->source);
+
+			if (WARN_RATELIMIT(!src, "No SGI source for INTID %d\n",
+					   irq->intid))
+				return 0;
+
+			val |= (src - 1) << GICH_LR_PHYSID_CPUID_SHIFT;
+			if (irq->source & ~BIT(src - 1))
+				val |= ICH_LR_EOI;
+		}
+	}
+
+	if (irq->group)
+		val |= ICH_LR_GROUP;
+
+	val |= (u64)irq->priority << ICH_LR_PRIORITY_SHIFT;
+
+	return val;
+}
+
+void vgic_v3_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr)
+{
+	u32 model = vcpu->kvm->arch.vgic.vgic_model;
+	u64 val = vgic_v3_compute_lr(vcpu, irq);
+
+	vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[lr] = val;
+
+	if (val & ICH_LR_PENDING_BIT) {
 		if (irq->config == VGIC_CONFIG_EDGE)
 			irq->pending_latch = false;
 
@@ -161,16 +190,9 @@ void vgic_v3_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr)
 		    model == KVM_DEV_TYPE_ARM_VGIC_V2) {
 			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->source &= ~BIT(src - 1);
+			if (irq->source)
 				irq->pending_latch = true;
-				val |= ICH_LR_EOI;
-			}
 		}
 	}
 
@@ -183,13 +205,6 @@ void vgic_v3_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr)
 	if (vgic_irq_is_mapped_level(irq) && (val & ICH_LR_PENDING_BIT))
 		irq->line_level = false;
 
-	if (irq->group)
-		val |= ICH_LR_GROUP;
-
-	val |= (u64)irq->priority << ICH_LR_PRIORITY_SHIFT;
-
-	vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[lr] = val;
-
 	irq->on_lr = true;
 }
 
-- 
2.47.3