KVM: arm64: arch_timer: Remove VGIC initialization check

kvm_timer_enable() is called in kvm_vcpu_first_run_init() after
kvm_vgic_map_resources() if the VGIC wasn't ready. kvm_vgic_map_resources()
is the only place where kvm->arch.vgic.ready is set to true.

For a v2 VGIC, kvm_vgic_map_resources() will attempt to initialize the VGIC
and set the initialized flag.

For a v3 VGIC, kvm_vgic_map_resources() will return an error code if the
VGIC isn't already initialized.

The end result is that if we've reached kvm_timer_enable(), the VGIC is
initialzed and ready and vgic_initialized() will always be true, so remove
this check.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
[maz: added comment about vgic initialisation, as suggested by Eric]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201201150157.223625-3-alexandru.elisei@arm.com

arch/arm64/kvm/arch_timer.c

@@ -1129,9 +1129,10 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
 	if (!irqchip_in_kernel(vcpu->kvm))
 		goto no_vgic;
 
-	if (!vgic_initialized(vcpu->kvm))
-		return -ENODEV;
-
+	/*
+	 * At this stage, we have the guarantee that the vgic is both
+	 * available and initialized.
+	 */
 	if (!timer_irqs_are_valid(vcpu)) {
 		kvm_debug("incorrectly configured timer irqs\n");
 		return -EINVAL;