KVM: Remove ability to assign a device without iommu support

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>

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 7945b0b..ee2c96b 100644 (file)
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1151,6 +1151,9 @@ following flags are specified:
 /* Depends on KVM_CAP_IOMMU */
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU    (1 << 0)
 
+The KVM_DEV_ASSIGN_ENABLE_IOMMU flag is a mandatory option to ensure
+isolation of the device.  Usages not specifying this flag are deprecated.
+
 4.49 KVM_DEASSIGN_PCI_DEVICE
 
 Capability: KVM_CAP_DEVICE_DEASSIGNMENT

diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index 3ad0925..a251a28 100644 (file)
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -487,6 +487,9 @@ 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;
+
        mutex_lock(&kvm->lock);
        idx = srcu_read_lock(&kvm->srcu);
 
@@ -544,16 +547,14 @@ 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:
        srcu_read_unlock(&kvm->srcu, idx);
@@ -593,8 +594,7 @@ 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);