linux-kernel - Re: [RFC v4 7/8] hisi_acc_vfio_pci: Add support for VFIO live migration

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Date:   Wed, 9 Feb 2022 16:44:40 -0700
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
Cc:     <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-crypto@...r.kernel.org>, <jgg@...dia.com>,
        <cohuck@...hat.com>, <mgurtovoy@...dia.com>, <yishaih@...dia.com>,
        <linuxarm@...wei.com>, <liulongfang@...wei.com>,
        <prime.zeng@...ilicon.com>, <jonathan.cameron@...wei.com>,
        <wangzhou1@...ilicon.com>
Subject: Re: [RFC v4 7/8] hisi_acc_vfio_pci: Add support for VFIO live
 migration

On Tue, 8 Feb 2022 13:34:24 +0000
Shameer Kolothum <shameerali.kolothum.thodi@...wei.com> wrote:
> +
> +static struct hisi_acc_vf_migration_file *
> +hisi_acc_vf_stop_copy(struct hisi_acc_vf_core_device *hisi_acc_vdev)
> +{
> +	struct hisi_qm *vf_qm = &hisi_acc_vdev->vf_qm;
> +	struct device *dev = &hisi_acc_vdev->vf_dev->dev;
> +	struct hisi_acc_vf_migration_file *migf;
> +	int ret;
> +
> +	if (unlikely(qm_wait_dev_not_ready(vf_qm))) {
> +		dev_info(dev, "QM device not ready, no data to transfer\n");
> +		return 0;
> +	}

This return value looks suspicious and I think would cause a segfault
in the calling code:

+		migf = hisi_acc_vf_stop_copy(hisi_acc_vdev);
+		if (IS_ERR(migf))
+			return ERR_CAST(migf);
+		get_file(migf->filp);
+		hisi_acc_vdev->saving_migf = migf;
+		return migf->filp;

Thanks,
Alex