Re: [PATCH v2 2/2] KVM: arm64: vgic-its: Remove the pending state of a discarded LPI

[Fuad Tabba <fuad.tabba@linux.dev>]

Hi Marc,

In case it saves you writing it, this is what I tested on top of v2
and your series:

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index d24c391e0aae2..37059d1338406 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -834,25 +834,34 @@ static int vgic_its_cmd_handle_discard(struct kvm *kvm, struct vgic_its *its,
 		int ite_esz = vgic_its_get_abi(its)->ite_esz;
 		gpa_t gpa = device->itt_addr + ite->event_id * ite_esz;
 		struct vgic_irq *irq = ite->irq;
-		bool queued;
+		struct kvm_vcpu *vcpu, *target;
 
 		vgic_its_invalidate_cache(its);
 
 		/*
-		 * A queued LPI can be pending in a running vCPU's list register,
-		 * which the exit path folds back: halt the guest before clearing.
+		 * Only an LPI on a vCPU's AP list can be in its list registers,
+		 * which the exit path folds back, and that exit moves the LPI
+		 * to its target vCPU if the target has changed: pause both.
 		 */
-		scoped_guard(raw_spinlock_irqsave, &irq->irq_lock)
-			queued = irq->vcpu;
+		scoped_guard(raw_spinlock_irqsave, &irq->irq_lock) {
+			vcpu = irq->vcpu;
+			target = irq->target_vcpu;
+		}
 
-		if (queued)
-			kvm_arm_halt_guest(kvm);
+		if (vcpu) {
+			if (target != vcpu)
+				kvm_pause_vcpu(target);
+			kvm_pause_vcpu(vcpu);
+		}
 
 		scoped_guard(raw_spinlock_irqsave, &irq->irq_lock)
 			irq->pending_latch = false;
 
-		if (queued)
-			kvm_arm_resume_guest(kvm);
+		if (vcpu) {
+			kvm_resume_vcpu(vcpu);
+			if (target != vcpu)
+				kvm_resume_vcpu(target);
+		}
 
 		its_free_ite(kvm, ite);
 

Cheers,
/fuad