KVM: Move wiping of the kvm->vcpus array to common code

All architectures have similar loops iterating over the vcpus,
freeing one vcpu at a time, and eventually wiping the reference
off the vcpus array. They are also inconsistently taking
the kvm->lock mutex when wiping the references from the array.

Make this code common, which will simplify further changes.
The locking is dropped altogether, as this should only be called
when there is no further references on the kvm structure.

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Message-Id: <20211116160403.4074052-2-maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/mips/kvm/mips.c

@@ -171,25 +171,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	return 0;
 }
 
-void kvm_mips_free_vcpus(struct kvm *kvm)
-{
-	unsigned int i;
-	struct kvm_vcpu *vcpu;
-
-	kvm_for_each_vcpu(i, vcpu, kvm) {
-		kvm_vcpu_destroy(vcpu);
-	}
-
-	mutex_lock(&kvm->lock);
-
-	for (i = 0; i < atomic_read(&kvm->online_vcpus); i++)
-		kvm->vcpus[i] = NULL;
-
-	atomic_set(&kvm->online_vcpus, 0);
-
-	mutex_unlock(&kvm->lock);
-}
-
 static void kvm_mips_free_gpa_pt(struct kvm *kvm)
 {
 	/* It should always be safe to remove after flushing the whole range */
@@ -199,7 +180,7 @@ static void kvm_mips_free_gpa_pt(struct kvm *kvm)
 
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
-	kvm_mips_free_vcpus(kvm);
+	kvm_destroy_vcpus(kvm);
 	kvm_mips_free_gpa_pt(kvm);
 }