3 files changed, 74 insertions, 0 deletions

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c96739b4b7a3..ce5d1c17ce26 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -334,6 +334,8 @@ int kvm_iommu_map_guest(struct kvm *kvm);
 int kvm_iommu_unmap_guest(struct kvm *kvm);
 int kvm_assign_device(struct kvm *kvm,
                       struct kvm_assigned_dev_kernel *assigned_dev);
+int kvm_deassign_device(struct kvm *kvm,
+                        struct kvm_assigned_dev_kernel *assigned_dev);
 #else /* CONFIG_DMAR */
 static inline int kvm_iommu_map_pages(struct kvm *kvm,
                                       gfn_t base_gfn,
@@ -357,6 +359,12 @@ static inline int kvm_assign_device(struct kvm *kvm,
 {
         return 0;
 }
+
+static inline int kvm_deassign_device(struct kvm *kvm,
+                struct kvm_assigned_dev_kernel *assigned_dev)
+{
+        return 0;
+}
 #endif /* CONFIG_DMAR */
 
 static inline void kvm_guest_enter(void)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c92b63462b79..3238e08e4651 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -530,6 +530,35 @@ out_free:
 }
 #endif
 
+#ifdef KVM_CAP_DEVICE_DEASSIGNMENT
+static int kvm_vm_ioctl_deassign_device(struct kvm *kvm,
+                struct kvm_assigned_pci_dev *assigned_dev)
+{
+        int r = 0;
+        struct kvm_assigned_dev_kernel *match;
+
+        mutex_lock(&kvm->lock);
+
+        match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
+                                      assigned_dev->assigned_dev_id);
+        if (!match) {
+                printk(KERN_INFO "%s: device hasn't been assigned before, "
+                  "so cannot be deassigned\n", __func__);
+                r = -EINVAL;
+                goto out;
+        }
+
+        if (assigned_dev->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU)
+                kvm_deassign_device(kvm, match);
+
+        kvm_free_assigned_device(kvm, match);
+
+out:
+        mutex_unlock(&kvm->lock);
+        return r;
+}
+#endif
+
 static inline int valid_vcpu(int n)
 {
         return likely(n >= 0 && n < KVM_MAX_VCPUS);
@@ -1863,6 +1892,19 @@ static long kvm_vm_ioctl(struct file *filp,
                 break;
         }
 #endif
+#ifdef KVM_CAP_DEVICE_DEASSIGNMENT
+        case KVM_DEASSIGN_PCI_DEVICE: {
+                struct kvm_assigned_pci_dev assigned_dev;
+
+                r = -EFAULT;
+                if (copy_from_user(&assigned_dev, argp, sizeof assigned_dev))
+                        goto out;
+                r = kvm_vm_ioctl_deassign_device(kvm, &assigned_dev);
+                if (r)
+                        goto out;
+                break;
+        }
+#endif
         default:
                 r = kvm_arch_vm_ioctl(filp, ioctl, arg);
         }
diff --git a/virt/kvm/vtd.c b/virt/kvm/vtd.c
index 44bb58a395a5..174ea1f8cee5 100644
--- a/virt/kvm/vtd.c
+++ b/virt/kvm/vtd.c
@@ -116,6 +116,30 @@ int kvm_assign_device(struct kvm *kvm,
         return 0;
 }
 
+int kvm_deassign_device(struct kvm *kvm,
+                        struct kvm_assigned_dev_kernel *assigned_dev)
+{
+        struct dmar_domain *domain = kvm->arch.intel_iommu_domain;
+        struct pci_dev *pdev = NULL;
+
+        /* check if iommu exists and in use */
+        if (!domain)
+                return 0;
+
+        pdev = assigned_dev->dev;
+        if (pdev == NULL)
+                return -ENODEV;
+
+        intel_iommu_detach_device(domain, pdev);
+
+        printk(KERN_DEBUG "deassign device: host bdf = %x:%x:%x\n",
+                assigned_dev->host_busnr,
+                PCI_SLOT(assigned_dev->host_devfn),
+                PCI_FUNC(assigned_dev->host_devfn));
+
+        return 0;
+}
+
 int kvm_iommu_map_guest(struct kvm *kvm)
 {
         int r;