linux-kernel - Re: [PATCH v6 4/5] hisi_acc_vfio_pci: bugfix the problem of uninstalling driver

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Message-ID: <20250321095150.7fe81186.alex.williamson@redhat.com>
Date: Fri, 21 Mar 2025 09:51:50 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: Longfang Liu <liulongfang@...wei.com>
Cc: <jgg@...dia.com>, <shameerali.kolothum.thodi@...wei.com>,
 <jonathan.cameron@...wei.com>, <kvm@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>, <linuxarm@...neuler.org>
Subject: Re: [PATCH v6 4/5] hisi_acc_vfio_pci: bugfix the problem of
 uninstalling driver

On Tue, 18 Mar 2025 14:45:47 +0800
Longfang Liu <liulongfang@...wei.com> wrote:

> In a live migration scenario. If the number of VFs at the
> destination is greater than the source, the recovery operation
> will fail and qemu will not be able to complete the process and
> exit after shutting down the device FD.
> 
> This will cause the driver to be unable to be unloaded normally due
> to abnormal reference counting of the live migration driver caused
> by the abnormal closing operation of fd.

"Therefore, make sure the migration file descriptor references are
 always released when the device is closed."

The commit log identifies the problem, but it's generally also useful
to describe the resolution of the problem as well.  Thanks,

Alex

> Fixes: b0eed085903e ("hisi_acc_vfio_pci: Add support for VFIO live migration")
> Signed-off-by: Longfang Liu <liulongfang@...wei.com>
> Reviewed-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
> ---
>  drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> index d96446f499ed..cadc82419dca 100644
> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> @@ -1508,6 +1508,7 @@ static void hisi_acc_vfio_pci_close_device(struct vfio_device *core_vdev)
>  	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(core_vdev);
>  	struct hisi_qm *vf_qm = &hisi_acc_vdev->vf_qm;
>  
> +	hisi_acc_vf_disable_fds(hisi_acc_vdev);
>  	mutex_lock(&hisi_acc_vdev->open_mutex);
>  	hisi_acc_vdev->dev_opened = false;
>  	iounmap(vf_qm->io_base);