KVM: arm64: vgic-v3: Trap all if no in-kernel irqchip

If there is no in-kernel irqchip for a GICv3 host set all of the trap
bits to block all accesses. This fixes the no-vgic-v3 selftest again.

Fixes: 3193287 ("KVM: arm64: gic-v3: Only set ICH_HCR traps for v2-on-v3 or v3 guests")
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/all/23072856-6b8c-41e2-93d1-ea8a240a7079@sirena.org.uk
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Reviewed-by: Sebastian Ott <sebott@redhat.com>
Tested-by: Mark Brown <broonie@kernel.org>
Link: https://patch.msgid.link/20251021094358.1963807-1-sascha.bischoff@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: Sticklyman1936

arch/arm64/kvm/vgic/vgic-v3.c

@@ -301,7 +301,8 @@ void vcpu_set_ich_hcr(struct kvm_vcpu *vcpu)
 		return;
 
 	/* Hide GICv3 sysreg if necessary */
-	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V2) {
+	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V2 ||
+	    !irqchip_in_kernel(vcpu->kvm)) {
 		vgic_v3->vgic_hcr |= (ICH_HCR_EL2_TALL0 | ICH_HCR_EL2_TALL1 |
 				      ICH_HCR_EL2_TC);
 		return;