linux-kernel - Re: [PATCH v10 3/5] hisi_acc_vfio_pci: register debugfs for hisilicon migration driver

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Date:   Fri, 14 Apr 2023 09:24:43 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Longfang Liu <liulongfang@...wei.com>
Cc:     alex.williamson@...hat.com, shameerali.kolothum.thodi@...wei.com,
        jonathan.cameron@...wei.com, cohuck@...hat.com,
        linux-kernel@...r.kernel.org, linuxarm@...neuler.org
Subject: Re: [PATCH v10 3/5] hisi_acc_vfio_pci: register debugfs for
 hisilicon migration driver

On Sat, Apr 08, 2023 at 03:42:22PM +0800, Longfang Liu wrote:
> +static int hisi_acc_vf_debug_restore(struct seq_file *seq, void *data)
> +{
> +	struct device *vf_dev = seq->private;
> +	struct vfio_pci_core_device *core_device = dev_get_drvdata(vf_dev);
> +	struct vfio_device	*vdev = &core_device->vdev;
> +	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev);
> +	struct hisi_acc_vf_migration_file *migf = hisi_acc_vdev->debug_migf;
> +	int ret;
> +
> +	ret = hisi_acc_vf_debug_check(seq, vdev);
> +	if (ret)
> +		goto restore_err;
> +
> +	ret = vf_qm_state_save(hisi_acc_vdev, migf);
> +	if (ret) {
> +		seq_printf(seq, "%s\n", "failed to save device data!");
> +		goto restore_err;
> +	}
> +
> +	ret = vf_qm_check_match(hisi_acc_vdev, migf);
> +	if (ret) {
> +		seq_printf(seq, "%s\n", "failed to match the VF!");
> +		goto restore_err;
> +	}
> +
> +	ret = vf_qm_load_data(hisi_acc_vdev, migf);
> +	if (ret) {
> +		seq_printf(seq, "%s\n", "failed to recover the VF!");
> +		goto restore_err;
> +	}
> +
> +	vf_qm_fun_reset(&hisi_acc_vdev->vf_qm);
> +	seq_printf(seq, "%s\n", "successful to resume device data!");
> +
> +restore_err:
> +	return 0;
> +}

This is basically an in-kernel self test, it should be protected with
some kind of VFIO selftest kconfig.

Though, I wonder why we need it??? Can't you write a trivial userspace
program under tools/testing to do this sequence with the ioctls?

> +static int hisi_acc_vf_debug_save(struct seq_file *seq, void *data)
> +{
> +	struct device *vf_dev = seq->private;
> +	struct vfio_pci_core_device *core_device = dev_get_drvdata(vf_dev);
> +	struct vfio_device	*vdev = &core_device->vdev;
> +	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev);
> +	struct hisi_acc_vf_migration_file *migf = hisi_acc_vdev->debug_migf;
> +	int ret;
> +
> +	ret = hisi_acc_vf_debug_check(seq, vdev);
> +	if (ret)
> +		goto save_err;
> +
> +	ret = vf_qm_state_save(hisi_acc_vdev, migf);
> +	if (ret) {
> +		seq_printf(seq, "%s\n", "failed to save device data!");
> +		goto save_err;
> +	}
> +	seq_printf(seq, "%s\n", "successful to save device data!");
> +
> +save_err:
> +	return 0;
> +}

Same kind of commen there, this is a selftest, why does it need a
special kernel interface?

.. and so on..

I thought the non-selftesty bits were OK, maybe split the patch to
match progress

Jason