linux-kernel - Re: [PATCH 01/17] dmaengine: idxd: Add enable/disable device IOPF feature

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Date:   Wed, 12 Apr 2023 10:22:49 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     Joerg Roedel <joro@...tes.org>, Tina Zhang <tina.zhang@...el.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        iommu@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/17] dmaengine: idxd: Add enable/disable device IOPF
 feature

On 11-04-23, 14:47, Lu Baolu wrote:
> The iommu subsystem requires IOMMU_DEV_FEAT_IOPF must be enabled before
> and disabled after IOMMU_DEV_FEAT_SVA, if device's I/O page faults rely
> on the IOMMU. Add explicit IOMMU_DEV_FEAT_IOPF enabling/disabling in this
> driver.
> 
> At present, missing IOPF enabling/disabling doesn't cause any real issue,
> because the IOMMU driver places the IOPF enabling/disabling in the path
> of SVA feature handling. But this may change.

Acked-by: Vinod Koul <vkoul@...nel.org>

> 
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> Reviewed-by: Fenghua Yu <fenghua.yu@...el.com>
> Reviewed-by: Kevin Tian <kevin.tian@...el.com>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> Link: https://lore.kernel.org/r/20230324120234.313643-2-baolu.lu@linux.intel.com
> ---
>  drivers/dma/idxd/init.c | 31 +++++++++++++++++++++++++------
>  1 file changed, 25 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index 640d3048368e..09ef62aa0635 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -516,6 +516,27 @@ static void idxd_disable_system_pasid(struct idxd_device *idxd)
>  	idxd->sva = NULL;
>  }
>  
> +static int idxd_enable_sva(struct pci_dev *pdev)
> +{
> +	int ret;
> +
> +	ret = iommu_dev_enable_feature(&pdev->dev, IOMMU_DEV_FEAT_IOPF);
> +	if (ret)
> +		return ret;
> +
> +	ret = iommu_dev_enable_feature(&pdev->dev, IOMMU_DEV_FEAT_SVA);
> +	if (ret)
> +		iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_IOPF);
> +
> +	return ret;
> +}
> +
> +static void idxd_disable_sva(struct pci_dev *pdev)
> +{
> +	iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_SVA);
> +	iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_IOPF);
> +}
> +
>  static int idxd_probe(struct idxd_device *idxd)
>  {
>  	struct pci_dev *pdev = idxd->pdev;
> @@ -530,7 +551,7 @@ static int idxd_probe(struct idxd_device *idxd)
>  	dev_dbg(dev, "IDXD reset complete\n");
>  
>  	if (IS_ENABLED(CONFIG_INTEL_IDXD_SVM) && sva) {
> -		if (iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA)) {
> +		if (idxd_enable_sva(pdev)) {
>  			dev_warn(dev, "Unable to turn on user SVA feature.\n");
>  		} else {
>  			set_bit(IDXD_FLAG_USER_PASID_ENABLED, &idxd->flags);
> @@ -578,21 +599,19 @@ static int idxd_probe(struct idxd_device *idxd)
>  	if (device_pasid_enabled(idxd))
>  		idxd_disable_system_pasid(idxd);
>  	if (device_user_pasid_enabled(idxd))
> -		iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_SVA);
> +		idxd_disable_sva(pdev);
>  	return rc;
>  }
>  
>  static void idxd_cleanup(struct idxd_device *idxd)
>  {
> -	struct device *dev = &idxd->pdev->dev;
> -
>  	perfmon_pmu_remove(idxd);
>  	idxd_cleanup_interrupts(idxd);
>  	idxd_cleanup_internals(idxd);
>  	if (device_pasid_enabled(idxd))
>  		idxd_disable_system_pasid(idxd);
>  	if (device_user_pasid_enabled(idxd))
> -		iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_SVA);
> +		idxd_disable_sva(idxd->pdev);
>  }
>  
>  static int idxd_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> @@ -710,7 +729,7 @@ static void idxd_remove(struct pci_dev *pdev)
>  	pci_free_irq_vectors(pdev);
>  	pci_iounmap(pdev, idxd->reg_base);
>  	if (device_user_pasid_enabled(idxd))
> -		iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_SVA);
> +		idxd_disable_sva(pdev);
>  	pci_disable_device(pdev);
>  	destroy_workqueue(idxd->wq);
>  	perfmon_pmu_remove(idxd);
> -- 
> 2.34.1

-- 
~Vinod