KVM: Add kvm_arch_vcpu_precreate() to handle pre-allocation issues

Add a pre-allocation arch hook to handle checks that are currently done
by arch specific code prior to allocating the vCPU object.  This paves
the way for moving the allocation to common KVM code.

Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 15 insertions, 10 deletions

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index adae134cec59..af3ce2bb370d 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -279,21 +279,22 @@ void kvm_arch_free_vm(struct kvm *kvm)
 		vfree(kvm);
 }
 
+int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
+{
+	if (irqchip_in_kernel(kvm) && vgic_initialized(kvm))
+		return -EBUSY;
+
+	if (id >= kvm->arch.max_vcpus)
+		return -EINVAL;
+
+	return 0;
+}
+
 struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
 {
 	int err;
 	struct kvm_vcpu *vcpu;
 
-	if (irqchip_in_kernel(kvm) && vgic_initialized(kvm)) {
-		err = -EBUSY;
-		goto out;
-	}
-
-	if (id >= kvm->arch.max_vcpus) {
-		err = -EINVAL;
-		goto out;
-	}
-
 	vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);
 	if (!vcpu) {
 		err = -ENOMEM;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 483c683408a2..7b52207f829c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2728,6 +2728,10 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 	kvm->created_vcpus++;
 	mutex_unlock(&kvm->lock);
 
+	r = kvm_arch_vcpu_precreate(kvm, id);
+	if (r)
+		goto vcpu_decrement;
+
 	vcpu = kvm_arch_vcpu_create(kvm, id);
 	if (IS_ERR(vcpu)) {
 		r = PTR_ERR(vcpu);