KVM: arm/arm64: Enable irqchip routing

This patch adds compilation and link against irqchip.

Main motivation behind using irqchip code is to enable MSI
routing code. In the future irqchip routing may also be useful
when targeting multiple irqchips.

Routing standard callbacks now are implemented in vgic-irqfd:
- kvm_set_routing_entry
- kvm_set_irq
- kvm_set_msi

They only are supported with new_vgic code.

Both HAVE_KVM_IRQCHIP and HAVE_KVM_IRQ_ROUTING are defined.
KVM_CAP_IRQ_ROUTING is advertised and KVM_SET_GSI_ROUTING is allowed.

So from now on IRQCHIP routing is enabled and a routing table entry
must exist for irqfd injection to succeed for a given SPI. This patch
builds a default flat irqchip routing table (gsi=irqchip.pin) covering
all the VGIC SPI indexes. This routing table is overwritten by the
first first user-space call to KVM_SET_GSI_ROUTING ioctl.

MSI routing setup is not yet allowed.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 540da51..19b698e 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -34,6 +34,7 @@
 #define VGIC_MAX_SPI		1019
 #define VGIC_MAX_RESERVED	1023
 #define VGIC_MIN_LPI		8192
+#define KVM_IRQCHIP_NUM_PINS	(1020 - 32)
 
 enum vgic_type {
 	VGIC_V2,		/* Good ol' GICv2 */
@@ -314,4 +315,10 @@
 
 int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi);
 
+/**
+ * kvm_vgic_setup_default_irq_routing:
+ * Setup a default flat gsi routing table mapping all SPIs
+ */
+int kvm_vgic_setup_default_irq_routing(struct kvm *kvm);
+
 #endif /* __KVM_ARM_VGIC_H */