KVM: arm64: Keep nVHE EL2 vector installed

KVM by default keeps the stub vector installed and installs the nVHE
vector only briefly for init and later on demand. Change this policy
to install the vector at init and then never uninstall it if the kernel
was given the protected KVM command line parameter.
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201202184122.26046-25-dbrazdil@google.com

arch/arm64/kvm/arm.c

@@ -1453,6 +1453,7 @@ static void _kvm_arch_hardware_disable(void *discard)
 
 void kvm_arch_hardware_disable(void)
 {
+	if (!is_protected_kvm_enabled())
 		_kvm_arch_hardware_disable(NULL);
 }
 
@@ -1496,10 +1497,12 @@ static struct notifier_block hyp_init_cpu_pm_nb = {
 
 static void __init hyp_cpu_pm_init(void)
 {
+	if (!is_protected_kvm_enabled())
 		cpu_pm_register_notifier(&hyp_init_cpu_pm_nb);
 }
 static void __init hyp_cpu_pm_exit(void)
 {
+	if (!is_protected_kvm_enabled())
 		cpu_pm_unregister_notifier(&hyp_init_cpu_pm_nb);
 }
 #else
@@ -1588,6 +1591,7 @@ static int init_subsystems(void)
 	kvm_coproc_table_init();
 
 out:
+	if (err || !is_protected_kvm_enabled())
 		on_each_cpu(_kvm_arch_hardware_disable, NULL, 1);
 
 	return err;