KVM: Remove ability to assign a device without iommu support
Alex Williamson [Thu, 12 Jan 2012 10:39:53 +0000 (12:39 +0200)]
(cherry picked from commit 423873736b78f549fbfa2f715f2e4de7e6c5e1e9)

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Documentation/virtual/kvm/api.txt
virt/kvm/assigned-dev.c

index b0e4b9c..57c9336 100644 (file)
@@ -1131,6 +1131,9 @@ 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
index 4e9eaeb..2269d71 100644 (file)
@@ -481,6 +481,9 @@ 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);
 
@@ -538,16 +541,14 @@ 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);
@@ -587,8 +588,7 @@ 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);