linux-kernel - Re: [PATCH v4 5/8] dmaengine: idxd: Remove unnecessary IOMMU_DEV_FEAT

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Message-ID: <5ea99aee-0b94-4373-9c17-5d1bb6662f9b@intel.com>
Date: Tue, 18 Mar 2025 18:20:04 +0800
From: Yi Liu <yi.l.liu@...el.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>, "Will
 Deacon" <will@...nel.org>, Robin Murphy <robin.murphy@....com>, "Jason
 Gunthorpe" <jgg@...pe.ca>, Kevin Tian <kevin.tian@...el.com>
CC: Dave Jiang <dave.jiang@...el.com>, Vinod Koul <vkoul@...nel.org>, "Fenghua
 Yu" <fenghuay@...dia.com>, Zhangfei Gao <zhangfei.gao@...aro.org>, Zhou Wang
	<wangzhou1@...ilicon.com>, <iommu@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>, Jason Gunthorpe <jgg@...dia.com>
Subject: Re: [PATCH v4 5/8] dmaengine: idxd: Remove unnecessary
 IOMMU_DEV_FEAT_IOPF

On 2025/3/13 13:19, Lu Baolu wrote:
> The IOMMU_DEV_FEAT_IOPF implementation in the iommu driver is just a no-op.
> It will also be removed from the iommu driver in the subsequent patch.
> Remove it to avoid dead code.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> Acked-by: Vinod Koul <vkoul@...nel.org>
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> Reviewed-by: Fenghua Yu <fenghuay@...dia.com>
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
> Reviewed-by: Kevin Tian <kevin.tian@...el.com>
> Tested-by: Zhangfei Gao <zhangfei.gao@...aro.org>
> ---
>   drivers/dma/idxd/init.c | 37 ++++++-------------------------------
>   1 file changed, 6 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index 1e5038cca22c..d44944195807 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -626,21 +626,6 @@ static void idxd_disable_system_pasid(struct idxd_device *idxd)
>   	idxd->pasid = IOMMU_PASID_INVALID;
>   }
>   
> -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;
> -	return 0;
> -}
> -
> -static void idxd_disable_sva(struct pci_dev *pdev)
> -{
> -	iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_IOPF);
> -}
> -
>   static int idxd_probe(struct idxd_device *idxd)
>   {
>   	struct pci_dev *pdev = idxd->pdev;
> @@ -655,17 +640,13 @@ static int idxd_probe(struct idxd_device *idxd)
>   	dev_dbg(dev, "IDXD reset complete\n");
>   
>   	if (IS_ENABLED(CONFIG_INTEL_IDXD_SVM) && 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);
> +		set_bit(IDXD_FLAG_USER_PASID_ENABLED, &idxd->flags);

a nit. The IDXD_FLAG_USER_PASID_ENABLED becomes almost equivalent to the
sva option. Is it ok?

This patch itself LGTM.

Reviewed-by: Yi Liu <yi.l.liu@...el.com>

-- 
Regards,
Yi Liu