KVM: arm64: Fix GICv4 init when called from vgic_its_create

Commit 3d1ad640 ("KVM: arm/arm64: Fix GICv4 ITS initialization
issues") moved the vgic_supports_direct_msis() check in vgic_v4_init().
However when vgic_v4_init is called from vgic_its_create(), the has_its
field is not yet set. Hence vgic_supports_direct_msis returns false and
vgic_v4_init does nothing.

The gic/its init sequence is a bit messy, so let's be specific about the
prerequisite checks in the various call paths instead of relying on a
common wrapper.

Fixes: 3d1ad640 ("KVM: arm/arm64: Fix GICv4 ITS initialization issues")
Reported-by: NEric Auger <eric.auger@redhat.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

virt/kvm/arm/vgic/vgic-init.c

@@ -285,9 +285,11 @@ int vgic_init(struct kvm *kvm)
 	if (ret)
 		goto out;
 
-	ret = vgic_v4_init(kvm);
-	if (ret)
-		goto out;
+	if (vgic_has_its(kvm)) {
+		ret = vgic_v4_init(kvm);
+		if (ret)
+			goto out;
+	}
 
 	kvm_for_each_vcpu(i, vcpu, kvm)
 		kvm_vgic_vcpu_enable(vcpu);

virt/kvm/arm/vgic/vgic-v4.c

@@ -118,7 +118,7 @@ int vgic_v4_init(struct kvm *kvm)
 	struct kvm_vcpu *vcpu;
 	int i, nr_vcpus, ret;
 
-	if (!vgic_supports_direct_msis(kvm))
+	if (!kvm_vgic_global_state.has_gicv4)
 		return 0; /* Nothing to see here... move along. */
 
 	if (dist->its_vm.vpes)