KVM: arm64: placeholder to check if VM is protected

Add a function to check whether a VM is protected (under pKVM).
Since the creation of protected VMs isn't enabled yet, this is a
placeholder that always returns false. The intention is for this
to become a check for protected VMs in the future (see Will's RFC).

No functional change intended.
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/kvmarm/20210603183347.1695-1-will@kernel.org/
Link: https://lore.kernel.org/r/20210817081134.2918285-2-tabba@google.com

arch/arm64/include/asm/kvm_host.h

@@ -771,6 +771,11 @@ void kvm_arch_free_vm(struct kvm *kvm);
 
 int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type);
 
+static inline bool kvm_vm_is_protected(struct kvm *kvm)
+{
+	return false;
+}
+
 int kvm_arm_vcpu_finalize(struct kvm_vcpu *vcpu, int feature);
 bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu);