linux-kernel - Re: [PATCH v5 7/8] hisi_acc_vfio_pci: Add support for VFIO live migration

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Date:   Wed, 23 Feb 2022 16:38:01 -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: [PATCH v5 7/8] hisi_acc_vfio_pci: Add support for VFIO live
 migration

On Mon, 21 Feb 2022 11:40:42 +0000
Shameer Kolothum <shameerali.kolothum.thodi@...wei.com> wrote:
> @@ -159,23 +1110,46 @@ static long hisi_acc_vfio_pci_ioctl(struct vfio_device *core_vdev, unsigned int
>  
>  static int hisi_acc_vfio_pci_open_device(struct vfio_device *core_vdev)
>  {
> -	struct vfio_pci_core_device *vdev =
> -		container_of(core_vdev, struct vfio_pci_core_device, vdev);
> +	struct hisi_acc_vf_core_device *hisi_acc_vdev = container_of(core_vdev,
> +			struct hisi_acc_vf_core_device, core_device.vdev);
> +	struct vfio_pci_core_device *vdev = &hisi_acc_vdev->core_device;
>  	int ret;
>  
>  	ret = vfio_pci_core_enable(vdev);
>  	if (ret)
>  		return ret;
>  
> -	vfio_pci_core_finish_enable(vdev);
> +	if (core_vdev->migration_flags != VFIO_MIGRATION_STOP_COPY) {

This looks like a minor synchronization issue with
hisi_acc_vfio_pci_migrn_init(), I think it might be cleaner to test
core_vdev->ops against the migration enabled set.

> +		vfio_pci_core_finish_enable(vdev);
> +		return 0;
> +	}
> +
> +	ret = hisi_acc_vf_qm_init(hisi_acc_vdev);
> +	if (ret) {
> +		vfio_pci_core_disable(vdev);
> +		return ret;
> +	}
>  
> +	hisi_acc_vdev->mig_state = VFIO_DEVICE_STATE_RUNNING;

Change the polarity of the if() above and encompass this all within
that branch scope so we can use the finish/return below for both cases?

> +
> +	vfio_pci_core_finish_enable(vdev);
>  	return 0;
>  }
>  
> +static void hisi_acc_vfio_pci_close_device(struct vfio_device *core_vdev)
> +{
> +	struct hisi_acc_vf_core_device *hisi_acc_vdev = container_of(core_vdev,
> +			struct hisi_acc_vf_core_device, core_device.vdev);
> +	struct hisi_qm *vf_qm = &hisi_acc_vdev->vf_qm;
> +
> +	iounmap(vf_qm->io_base);
> +	vfio_pci_core_close_device(core_vdev);
> +}
> +
>  static const struct vfio_device_ops hisi_acc_vfio_pci_migrn_ops = {
>  	.name = "hisi-acc-vfio-pci",
>  	.open_device = hisi_acc_vfio_pci_open_device,
> -	.close_device = vfio_pci_core_close_device,
> +	.close_device = hisi_acc_vfio_pci_close_device,
>  	.ioctl = hisi_acc_vfio_pci_ioctl,
>  	.device_feature = vfio_pci_core_ioctl_feature,
>  	.read = hisi_acc_vfio_pci_read,
> @@ -183,6 +1157,8 @@ static const struct vfio_device_ops hisi_acc_vfio_pci_migrn_ops = {
>  	.mmap = hisi_acc_vfio_pci_mmap,
>  	.request = vfio_pci_core_request,
>  	.match = vfio_pci_core_match,
> +	.migration_set_state = hisi_acc_vfio_pci_set_device_state,
> +	.migration_get_state = hisi_acc_vfio_pci_get_device_state,
>  };
>  
>  static const struct vfio_device_ops hisi_acc_vfio_pci_ops = {
> @@ -198,38 +1174,71 @@ static const struct vfio_device_ops hisi_acc_vfio_pci_ops = {
>  	.match = vfio_pci_core_match,
>  };
>  
> +static int
> +hisi_acc_vfio_pci_migrn_init(struct hisi_acc_vf_core_device *hisi_acc_vdev,
> +			     struct pci_dev *pdev, struct hisi_qm *pf_qm)
> +{
> +	int vf_id;
> +
> +	vf_id = pci_iov_vf_id(pdev);
> +	if (vf_id < 0)
> +		return vf_id;
> +
> +	hisi_acc_vdev->vf_id = vf_id + 1;
> +	hisi_acc_vdev->core_device.vdev.migration_flags =
> +					VFIO_MIGRATION_STOP_COPY;
> +	hisi_acc_vdev->pf_qm = pf_qm;
> +	hisi_acc_vdev->vf_dev = pdev;
> +	mutex_init(&hisi_acc_vdev->state_mutex);
> +
> +	return 0;
> +}
> +
>  static int hisi_acc_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  {
> -	struct vfio_pci_core_device *vdev;
> +	struct hisi_acc_vf_core_device *hisi_acc_vdev;
> +	struct hisi_qm *pf_qm;
>  	int ret;
>  
> -	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
> -	if (!vdev)
> +	hisi_acc_vdev = kzalloc(sizeof(*hisi_acc_vdev), GFP_KERNEL);
> +	if (!hisi_acc_vdev)
>  		return -ENOMEM;
>  
> -	vfio_pci_core_init_device(vdev, pdev, &hisi_acc_vfio_pci_ops);
> +	pf_qm = hisi_acc_get_pf_qm(pdev);
> +	if (pf_qm && pf_qm->ver >= QM_HW_V3) {
> +		ret = hisi_acc_vfio_pci_migrn_init(hisi_acc_vdev, pdev, pf_qm);
> +		if (ret < 0) {
> +			kfree(hisi_acc_vdev);
> +			return ret;
> +		}

This error path can only occur if the VF ID lookup fails, but should we
fall through to the non-migration ops, maybe with a dev_warn()?  Thanks,

Alex

> +
> +		vfio_pci_core_init_device(&hisi_acc_vdev->core_device, pdev,
> +					  &hisi_acc_vfio_pci_migrn_ops);
> +	} else {
> +		vfio_pci_core_init_device(&hisi_acc_vdev->core_device, pdev,
> +					  &hisi_acc_vfio_pci_ops);
> +	}