[PATCH v2 28/39] KVM: arm64: gic: Introduce set_pending_state() to irq_op

[Sascha Bischoff]

There are times, such as with GICv5 SPIs and LPIs, where the hardware
itself manages parts of the interrupt lifecycle. This means that
pending state can be directly communicated to the hardware instead of
being represented only in the VGIC shadow state.

In order to accommodate cases where the hardware handles pending state
directly, add a new set_pending_state() function pointer to
irq_ops. The intent is for this to be used after the VGIC shadow
pending state has changed, allowing the backend to mirror the updated
state into hardware.

This new function is plumbed into kvm_vgic_inject_irq(), and is only
called if irq_ops are provided and this function pointer is explicitly
set. In the general case, this has no effect.

Signed-off-by: Sascha Bischoff <sascha.bischoff at arm.com>
---
 arch/arm64/kvm/vgic/vgic.c | 3 +++
 include/kvm/arm_vgic.h     | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index d628eea4cfa4e..b35833a4e2bf9 100644
--- a/arch/arm64/kvm/vgic/vgic.c
+++ b/arch/arm64/kvm/vgic/vgic.c
@@ -565,6 +565,9 @@ int kvm_vgic_inject_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
 	else
 		irq->pending_latch = true;
 
+	if (irq->ops && irq->ops->set_pending_state)
+		WARN_ON_ONCE(!irq->ops->set_pending_state(vcpu, irq));
+
 	vgic_queue_irq_unlock(kvm, irq, flags);
 	vgic_put_irq(kvm, irq);
 
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index d4b0e7e3edf26..f9f58ca793707 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -250,6 +250,12 @@ struct irq_ops {
 	 */
 	bool (*get_input_level)(int vintid);
 
+	/*
+	 * Function pointer to directly update hardware pending state after the
+	 * VGIC shadow pending state has changed.
+	 */
+	bool (*set_pending_state)(struct kvm_vcpu *vcpu, struct vgic_irq *irq);
+
 	/*
 	 * Function pointer to override the queuing of an IRQ.
 	 */
-- 
2.34.1