linux-kernel - Re: [PATCH 1/2] dmaengine: idxd: Add enable/disable device IOPF feature

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Message-ID: <f4f377dc-143d-ea93-436f-334390e4c120@intel.com>
Date:   Fri, 3 Feb 2023 09:08:02 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>, iommu@...ts.linux.dev,
        dmaengine@...r.kernel.org
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Kevin Tian <kevin.tian@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Vinod Koul <vkoul@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] dmaengine: idxd: Add enable/disable device IOPF
 feature



On 2/3/23 1:44 AM, 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.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>

Reviewed-by: Dave Jiang <dave.jiang@...el.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 529ea09c9094..d5a709a842a8 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -511,6 +511,27 @@ 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;
> @@ -525,7 +546,7 @@ 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);
> @@ -573,21 +594,19 @@ 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)
> @@ -705,7 +724,7 @@ 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);