KVM: arm64: GICv4.1: Add function to get VLPI state

With GICv4.1 and the vPE unmapped, which indicates the invalidation
of any VPT caches associated with the vPE, we can get the VLPI state
by peeking at the VPT. So we add a function for this.
Signed-off-by: Shenming Lu <lushenming@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210322060158.1584-4-lushenming@huawei.com

arch/arm64/kvm/vgic/vgic-v4.c

@@ -203,6 +203,25 @@ void vgic_v4_configure_vsgis(struct kvm *kvm)
 	kvm_arm_resume_guest(kvm);
 }
 
+/*
+ * Must be called with GICv4.1 and the vPE unmapped, which
+ * indicates the invalidation of any VPT caches associated
+ * with the vPE, thus we can get the VLPI state by peeking
+ * at the VPT.
+ */
+void vgic_v4_get_vlpi_state(struct vgic_irq *irq, bool *val)
+{
+	struct its_vpe *vpe = &irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
+	int mask = BIT(irq->intid % BITS_PER_BYTE);
+	void *va;
+	u8 *ptr;
+
+	va = page_address(vpe->vpt_page);
+	ptr = va + irq->intid / BITS_PER_BYTE;
+
+	*val = !!(*ptr & mask);
+}
+
 /**
  * vgic_v4_init - Initialize the GICv4 data structures
  * @kvm:	Pointer to the VM being initialized

arch/arm64/kvm/vgic/vgic.h

@@ -317,5 +317,6 @@ bool vgic_supports_direct_msis(struct kvm *kvm);
 int vgic_v4_init(struct kvm *kvm);
 void vgic_v4_teardown(struct kvm *kvm);
 void vgic_v4_configure_vsgis(struct kvm *kvm);
+void vgic_v4_get_vlpi_state(struct vgic_irq *irq, bool *val);
 
 #endif