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From:   Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
To:     Alex Williamson <alex.williamson@redhat.com>
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        "Zengtao (B)" <prime.zeng@hisilicon.com>,
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Subject: RE: [RFC v4 7/8] hisi_acc_vfio_pci: Add support for VFIO live
 migration
Thread-Topic: [RFC v4 7/8] hisi_acc_vfio_pci: Add support for VFIO live
 migration
Thread-Index: AQHYHPDyAsbl+xVOv0mWAZg3hAhxZqyL5CAAgAEAYUA=
Date:   Thu, 10 Feb 2022 15:07:40 +0000
Message-ID: <e739f0cef853428e9d72ebc6e3c52187@huawei.com>
References: <20220208133425.1096-1-shameerali.kolothum.thodi@huawei.com>
        <20220208133425.1096-8-shameerali.kolothum.thodi@huawei.com>
 <20220209164440.0d77284c.alex.williamson@redhat.com>
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> -----Original Message-----
> From: Alex Williamson [mailto:alex.williamson@redhat.com]
> Sent: 09 February 2022 23:45
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> Cc: kvm@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-crypto@vger.kernel.org; jgg@nvidia.com; cohuck@redhat.com;
> mgurtovoy@nvidia.com; yishaih@nvidia.com; Linuxarm
> <linuxarm@huawei.com>; liulongfang <liulongfang@huawei.com>; Zengtao (B)
> <prime.zeng@hisilicon.com>; Jonathan Cameron
> <jonathan.cameron@huawei.com>; Wangzhou (B) <wangzhou1@hisilicon.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@huawei.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:

Ah..Right!. I think I can move the above to the vf_qm_state_save()
and use migf->total_length to handle this.

Thanks,
Shameer