Re: [PATCH 10/10] vfio/qat: Add vfio_pci driver for Intel QAT VF devices

Jason Gunthorpe
2024-02-06T12:55:06Z

On Thu, Feb 01, 2024 at 11:33:37PM +0800, Xin Zeng wrote:

> +static int qat_vf_pci_init_dev(struct vfio_device *core_vdev)
> +{
> + struct qat_vf_core_device *qat_vdev = container_of(core_vdev,
> + struct qat_vf_core_device, core_device.vdev);
> + struct qat_migdev_ops *ops;
> + struct qat_mig_dev *mdev;
> + struct pci_dev *parent;
> + int ret, vf_id;
> +
> + core_vdev->migration_flags = VFIO_MIGRATION_STOP_COPY | VFIO_MIGRATION_P2P;
> + core_vdev->mig_ops = &qat_vf_pci_mig_ops;
> +
> + ret = vfio_pci_core_init_dev(core_vdev);
> + if (ret)
> + return ret;
> +
> + mutex_init(&qat_vdev->state_mutex);
> + spin_lock_init(&qat_vdev->reset_lock);
> +
> + parent = qat_vdev->core_device.pdev->physfn;
> + vf_id = pci_iov_vf_id(qat_vdev->core_device.pdev);
> + if (!parent || vf_id < 0) {
> + ret = -ENODEV;
> + goto err_rel;
> + }
> +
> + mdev = qat_vfmig_create(parent, vf_id);
> + if (IS_ERR(mdev)) {
> + ret = PTR_ERR(mdev);
> + goto err_rel;
> + }
> +
> + ops = mdev->ops;
> + if (!ops || !ops->init || !ops->cleanup ||
> + !ops->open || !ops->close ||
> + !ops->save_state || !ops->load_state ||
> + !ops->suspend || !ops->resume) {
> + ret = -EIO;
> + dev_err(&parent->dev, "Incomplete device migration ops structure!");
> + goto err_destroy;
> + }

Why are there ops pointers here? I would expect this should just be
direct function calls to the PF QAT driver.

> +static void qat_vf_pci_aer_reset_done(struct pci_dev *pdev)
> +{
> + struct qat_vf_core_device *qat_vdev = qat_vf_drvdata(pdev);
> +
> + if (!qat_vdev->core_device.vdev.mig_ops)
> + return;
> +
> + /*
> + * As the higher VFIO layers are holding locks across reset and using
> + * those same locks with the mm_lock we need to prevent ABBA deadlock
> + * with the state_mutex and mm_lock.
> + * In case the state_mutex was taken already we defer the cleanup work
> + * to the unlock flow of the other running context.
> + */
> + spin_lock(&qat_vdev->reset_lock);
> + qat_vdev->deferred_reset = true;
> + if (!mutex_trylock(&qat_vdev->state_mutex)) {
> + spin_unlock(&qat_vdev->reset_lock);
> + return;
> + }
> + spin_unlock(&qat_vdev->reset_lock);
> + qat_vf_state_mutex_unlock(qat_vdev);
> +}

Do you really need this? I thought this ugly thing was going to be a
uniquely mlx5 thing..

Jason