KVM: Remove ability to assign a device without iommu support

commit 42387373 upstream

This option has no users and it exposes a security hole that we
can allow devices to be assigned without iommu protection.  Make
KVM_DEV_ASSIGN_ENABLE_IOMMU a mandatory option.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
[dannf: backported to Debian's 2.6.32]
Signed-off-by: Willy Tarreau <w@1wt.eu>

virt/kvm/kvm_main.c

@@ -582,6 +582,9 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 	struct kvm_assigned_dev_kernel *match;
 	struct pci_dev *dev;
 
+	if (!(assigned_dev->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU))
+		return -EINVAL;
+
 	down_read(&kvm->slots_lock);
 	mutex_lock(&kvm->lock);
 
@@ -635,16 +638,14 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 
 	list_add(&match->list, &kvm->arch.assigned_dev_head);
 
-	if (assigned_dev->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU) {
-		if (!kvm->arch.iommu_domain) {
-			r = kvm_iommu_map_guest(kvm);
-			if (r)
-				goto out_list_del;
-		}
-		r = kvm_assign_device(kvm, match);
+	if (!kvm->arch.iommu_domain) {
+		r = kvm_iommu_map_guest(kvm);
 		if (r)
 			goto out_list_del;
 	}
+	r = kvm_assign_device(kvm, match);
+	if (r)
+		goto out_list_del;
 
 out:
 	mutex_unlock(&kvm->lock);
@@ -683,8 +684,7 @@ static int kvm_vm_ioctl_deassign_device(struct kvm *kvm,
 		goto out;
 	}
 
-	if (match->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU)
-		kvm_deassign_device(kvm, match);
+	kvm_deassign_device(kvm, match);
 
 	kvm_free_assigned_device(kvm, match);