kvm: arm/arm64: Allow arch specific configurations for VM

Allow the arch backends to perform VM specific initialisation.
This will be later used to handle IPA size configuration and per-VM
VTCR configuration on arm64.

Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Christoffer Dall <cdall@kernel.org>
Reviewed-by: NEric Auger <eric.auger@redhat.com>
Signed-off-by: NSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

arch/arm/include/asm/kvm_host.h

@@ -354,4 +354,11 @@ static inline void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu) {}
 struct kvm *kvm_arch_alloc_vm(void);
 void kvm_arch_free_vm(struct kvm *kvm);
 
+static inline int kvm_arm_config_vm(struct kvm *kvm, unsigned long type)
+{
+	if (type)
+		return -EINVAL;
+	return 0;
+}
+
 #endif /* __ARM_KVM_HOST_H__ */

arch/arm64/include/asm/kvm_host.h

@@ -513,4 +513,6 @@ void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu);
 struct kvm *kvm_arch_alloc_vm(void);
 void kvm_arch_free_vm(struct kvm *kvm);
 
+int kvm_arm_config_vm(struct kvm *kvm, unsigned long type);
+
 #endif /* __ARM64_KVM_HOST_H__ */

arch/arm64/kvm/reset.c

@@ -133,3 +133,10 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 	/* Reset timer */
 	return kvm_timer_vcpu_reset(vcpu);
 }
+
+int kvm_arm_config_vm(struct kvm *kvm, unsigned long type)
+{
+	if (type)
+		return -EINVAL;
+	return 0;
+}

virt/kvm/arm/arm.c

@@ -120,8 +120,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 {
 	int ret, cpu;
 
-	if (type)
-		return -EINVAL;
+	ret = kvm_arm_config_vm(kvm, type);
+	if (ret)
+		return ret;
 
 	kvm->arch.last_vcpu_ran = alloc_percpu(typeof(*kvm->arch.last_vcpu_ran));
 	if (!kvm->arch.last_vcpu_ran)