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vfio/ccw: Use the new device life cycle helpers
ccw is the only exception which cannot use vfio_alloc_device() because its private device structure is designed to serve both mdev and parent. Life cycle of the parent is managed by css_driver so vfio_ccw_private must be allocated/freed in css_driver probe/remove path instead of conforming to vfio core life cycle for mdev. Given that use a wait/completion scheme so the mdev remove path waits after vfio_put_device() until receiving a completion notification from @release. The completion indicates that all active references on vfio_device have been released. After that point although free of vfio_ccw_private is delayed to css_driver it's at least guaranteed to have no parallel reference on released vfio device part from other code paths. memset() in @probe is removed. vfio_device is either already cleared when probed for the first time or cleared in @release from last probe. The right fix is to introduce separate structures for mdev and parent, but this won't happen in short term per prior discussions. Remove vfio_init/uninit_group_dev() as no user now. Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Kevin Tian <kevin.tian@intel.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Eric Farman <farman@linux.ibm.com> Link: https://lore.kernel.org/r/20220921104401.38898-14-kevin.tian@intel.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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@ -87,6 +87,15 @@ static struct attribute_group *mdev_type_groups[] = {
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NULL,
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};
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static int vfio_ccw_mdev_init_dev(struct vfio_device *vdev)
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{
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struct vfio_ccw_private *private =
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container_of(vdev, struct vfio_ccw_private, vdev);
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init_completion(&private->release_comp);
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return 0;
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}
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static int vfio_ccw_mdev_probe(struct mdev_device *mdev)
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{
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struct vfio_ccw_private *private = dev_get_drvdata(mdev->dev.parent);
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@ -98,9 +107,9 @@ static int vfio_ccw_mdev_probe(struct mdev_device *mdev)
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if (atomic_dec_if_positive(&private->avail) < 0)
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return -EPERM;
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memset(&private->vdev, 0, sizeof(private->vdev));
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vfio_init_group_dev(&private->vdev, &mdev->dev,
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&vfio_ccw_dev_ops);
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ret = vfio_init_device(&private->vdev, &mdev->dev, &vfio_ccw_dev_ops);
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if (ret)
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return ret;
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VFIO_CCW_MSG_EVENT(2, "sch %x.%x.%04x: create\n",
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private->sch->schid.cssid,
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@ -109,16 +118,33 @@ static int vfio_ccw_mdev_probe(struct mdev_device *mdev)
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ret = vfio_register_emulated_iommu_dev(&private->vdev);
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if (ret)
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goto err_atomic;
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goto err_put_vdev;
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dev_set_drvdata(&mdev->dev, private);
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return 0;
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err_atomic:
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vfio_uninit_group_dev(&private->vdev);
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err_put_vdev:
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vfio_put_device(&private->vdev);
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atomic_inc(&private->avail);
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return ret;
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}
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static void vfio_ccw_mdev_release_dev(struct vfio_device *vdev)
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{
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struct vfio_ccw_private *private =
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container_of(vdev, struct vfio_ccw_private, vdev);
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/*
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* We cannot free vfio_ccw_private here because it includes
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* parent info which must be free'ed by css driver.
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*
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* Use a workaround by memset'ing the core device part and
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* then notifying the remove path that all active references
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* to this device have been released.
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*/
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memset(vdev, 0, sizeof(*vdev));
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complete(&private->release_comp);
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}
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static void vfio_ccw_mdev_remove(struct mdev_device *mdev)
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{
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struct vfio_ccw_private *private = dev_get_drvdata(mdev->dev.parent);
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@ -130,7 +156,17 @@ static void vfio_ccw_mdev_remove(struct mdev_device *mdev)
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vfio_unregister_group_dev(&private->vdev);
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vfio_uninit_group_dev(&private->vdev);
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vfio_put_device(&private->vdev);
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/*
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* Wait for all active references on mdev are released so it
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* is safe to defer kfree() to a later point.
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*
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* TODO: the clean fix is to split parent/mdev info from ccw
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* private structure so each can be managed in its own life
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* cycle.
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*/
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wait_for_completion(&private->release_comp);
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atomic_inc(&private->avail);
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}
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@ -592,6 +628,8 @@ static void vfio_ccw_mdev_request(struct vfio_device *vdev, unsigned int count)
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}
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static const struct vfio_device_ops vfio_ccw_dev_ops = {
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.init = vfio_ccw_mdev_init_dev,
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.release = vfio_ccw_mdev_release_dev,
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.open_device = vfio_ccw_mdev_open_device,
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.close_device = vfio_ccw_mdev_close_device,
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.read = vfio_ccw_mdev_read,
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@ -88,6 +88,7 @@ struct vfio_ccw_crw {
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* @req_trigger: eventfd ctx for signaling userspace to return device
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* @io_work: work for deferral process of I/O handling
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* @crw_work: work for deferral process of CRW handling
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* @release_comp: synchronization helper for vfio device release
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*/
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struct vfio_ccw_private {
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struct vfio_device vdev;
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@ -113,6 +114,8 @@ struct vfio_ccw_private {
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struct eventfd_ctx *req_trigger;
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struct work_struct io_work;
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struct work_struct crw_work;
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struct completion release_comp;
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} __aligned(8);
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int vfio_ccw_sch_quiesce(struct subchannel *sch);
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@ -483,28 +483,13 @@ static struct vfio_device *vfio_group_get_device(struct vfio_group *group,
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/*
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* VFIO driver API
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*/
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void vfio_init_group_dev(struct vfio_device *device, struct device *dev,
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const struct vfio_device_ops *ops)
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{
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init_completion(&device->comp);
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device->dev = dev;
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device->ops = ops;
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}
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EXPORT_SYMBOL_GPL(vfio_init_group_dev);
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void vfio_uninit_group_dev(struct vfio_device *device)
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{
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vfio_release_device_set(device);
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}
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EXPORT_SYMBOL_GPL(vfio_uninit_group_dev);
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/* Release helper called by vfio_put_device() */
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void vfio_device_release(struct kref *kref)
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{
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struct vfio_device *device =
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container_of(kref, struct vfio_device, kref);
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vfio_uninit_group_dev(device);
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vfio_release_device_set(device);
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/*
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* kvfree() cannot be done here due to a life cycle mess in
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@ -562,7 +547,9 @@ int vfio_init_device(struct vfio_device *device, struct device *dev,
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{
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int ret;
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vfio_init_group_dev(device, dev, ops);
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init_completion(&device->comp);
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device->dev = dev;
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device->ops = ops;
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if (ops->init) {
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ret = ops->init(device);
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@ -574,7 +561,7 @@ int vfio_init_device(struct vfio_device *device, struct device *dev,
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return 0;
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out_uninit:
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vfio_uninit_group_dev(device);
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vfio_release_device_set(device);
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return ret;
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}
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EXPORT_SYMBOL_GPL(vfio_init_device);
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@ -184,9 +184,6 @@ static inline void vfio_put_device(struct vfio_device *device)
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kref_put(&device->kref, vfio_device_release);
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}
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void vfio_init_group_dev(struct vfio_device *device, struct device *dev,
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const struct vfio_device_ops *ops);
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void vfio_uninit_group_dev(struct vfio_device *device);
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int vfio_register_group_dev(struct vfio_device *device);
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int vfio_register_emulated_iommu_dev(struct vfio_device *device);
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void vfio_unregister_group_dev(struct vfio_device *device);
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