Merge git://git.kernel.org/pub/scm/virt/kvm/kvm

[mirror_ubuntu-bionic-kernel.git] / drivers / vfio / vfio.c

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 842f4507883e1b1d10c99d343e35e450abf56db0..1eab4ace06718ac38574414d11de280755de6334 100644 (file)
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1109,7 +1109,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
                 * We can't use anon_inode_getfd() because we need to modify
                 * the f_mode flags directly to allow more than just ioctls
                 */
-               ret = get_unused_fd();
+               ret = get_unused_fd_flags(O_CLOEXEC);
                if (ret < 0) {
                        device->ops->release(device->device_data);
                        break;
@@ -1352,6 +1352,68 @@ static const struct file_operations vfio_device_fops = {
        .mmap           = vfio_device_fops_mmap,
 };
 
+/**
+ * External user API, exported by symbols to be linked dynamically.
+ *
+ * The protocol includes:
+ *  1. do normal VFIO init operation:
+ *     - opening a new container;
+ *     - attaching group(s) to it;
+ *     - setting an IOMMU driver for a container.
+ * When IOMMU is set for a container, all groups in it are
+ * considered ready to use by an external user.
+ *
+ * 2. User space passes a group fd to an external user.
+ * The external user calls vfio_group_get_external_user()
+ * to verify that:
+ *     - the group is initialized;
+ *     - IOMMU is set for it.
+ * If both checks passed, vfio_group_get_external_user()
+ * increments the container user counter to prevent
+ * the VFIO group from disposal before KVM exits.
+ *
+ * 3. The external user calls vfio_external_user_iommu_id()
+ * to know an IOMMU ID.
+ *
+ * 4. When the external KVM finishes, it calls
+ * vfio_group_put_external_user() to release the VFIO group.
+ * This call decrements the container user counter.
+ */
+struct vfio_group *vfio_group_get_external_user(struct file *filep)
+{
+       struct vfio_group *group = filep->private_data;
+
+       if (filep->f_op != &vfio_group_fops)
+               return ERR_PTR(-EINVAL);
+
+       if (!atomic_inc_not_zero(&group->container_users))
+               return ERR_PTR(-EINVAL);
+
+       if (!group->container->iommu_driver ||
+                       !vfio_group_viable(group)) {
+               atomic_dec(&group->container_users);
+               return ERR_PTR(-EINVAL);
+       }
+
+       vfio_group_get(group);
+
+       return group;
+}
+EXPORT_SYMBOL_GPL(vfio_group_get_external_user);
+
+void vfio_group_put_external_user(struct vfio_group *group)
+{
+       vfio_group_put(group);
+       vfio_group_try_dissolve_container(group);
+}
+EXPORT_SYMBOL_GPL(vfio_group_put_external_user);
+
+int vfio_external_user_iommu_id(struct vfio_group *group)
+{
+       return iommu_group_id(group->iommu_group);
+}
+EXPORT_SYMBOL_GPL(vfio_external_user_iommu_id);
+
 /**
  * Module/class support
  */