diff options
Diffstat (limited to 'drivers/vfio/vfio.c')
| -rw-r--r-- | drivers/vfio/vfio.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 4ee4f361fe9f..f5a86f651f38 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -85,6 +85,7 @@ struct vfio_group { struct list_head unbound_list; struct mutex unbound_lock; atomic_t opened; + wait_queue_head_t container_q; bool noiommu; struct kvm *kvm; struct blocking_notifier_head notifier; @@ -338,6 +339,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group) mutex_init(&group->unbound_lock); atomic_set(&group->container_users, 0); atomic_set(&group->opened, 0); + init_waitqueue_head(&group->container_q); group->iommu_group = iommu_group; #ifdef CONFIG_VFIO_NOIOMMU group->noiommu = (iommu_group_get_iommudata(iommu_group) == &noiommu); @@ -994,6 +996,23 @@ void *vfio_del_group_dev(struct device *dev) } } while (ret <= 0); + /* + * In order to support multiple devices per group, devices can be + * plucked from the group while other devices in the group are still + * in use. The container persists with this group and those remaining + * devices still attached. If the user creates an isolation violation + * by binding this device to another driver while the group is still in + * use, that's their fault. However, in the case of removing the last, + * or potentially the only, device in the group there can be no other + * in-use devices in the group. The user has done their due diligence + * and we should lay no claims to those devices. In order to do that, + * we need to make sure the group is detached from the container. + * Without this stall, we're potentially racing with a user process + * that may attempt to immediately bind this device to another driver. + */ + if (list_empty(&group->device_list)) + wait_event(group->container_q, !group->container); + vfio_group_put(group); return device_data; @@ -1299,6 +1318,7 @@ static void __vfio_group_unset_container(struct vfio_group *group) group->iommu_group); group->container = NULL; + wake_up(&group->container_q); list_del(&group->container_next); /* Detaching the last group deprivileges a container, remove iommu */ |