linux-kernel - Re: [PATCH 1/2] iommu/vt-d: Report SVA feature with generic flag

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Message-ID: <20200320093025.GB1702630@myrica>
Date:   Fri, 20 Mar 2020 10:30:25 +0100
From:   Jean-Philippe Brucker <jean-philippe@...aro.org>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc:     iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Yi Liu <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Eric Auger <eric.auger@...hat.com>,
        Dave Jiang <dave.jiang@...el.com>
Subject: Re: [PATCH 1/2] iommu/vt-d: Report SVA feature with generic flag

On Mon, Feb 24, 2020 at 03:26:36PM -0800, Jacob Pan wrote:
> Query Shared Virtual Address/Memory capability is a generic feature.
> SVA feature check is the required first step before calling
> iommu_sva_bind_device().
> 
> VT-d checks SVA feature enabling at per IOMMU level during this step,
> SVA bind device will check and enable PCI ATS, PRS, and PASID capabilities
> at device level.
> 
> This patch reports Intel SVM as SVA feature such that generic code
> (e.g. Uacce [1]) can use it.
> 
> [1] https://lkml.org/lkml/2020/1/15/604
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>

Don't you also need to have has_feat(), feat_enabled() and disable_feat()
return positive values?

Thanks,
Jean

> ---
>  drivers/iommu/intel-iommu.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 92c2f2e4197b..5eca6e10d2a4 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -6346,9 +6346,14 @@ intel_iommu_dev_has_feat(struct device *dev, enum iommu_dev_features feat)
>  static int
>  intel_iommu_dev_enable_feat(struct device *dev, enum iommu_dev_features feat)
>  {
> +	struct intel_iommu *intel_iommu = dev_to_intel_iommu(dev);
> +
>  	if (feat == IOMMU_DEV_FEAT_AUX)
>  		return intel_iommu_enable_auxd(dev);
>  
> +	if (feat == IOMMU_DEV_FEAT_SVA)
> +		return intel_iommu->flags & VTD_FLAG_SVM_CAPABLE;
> +
>  	return -ENODEV;
>  }
>  
> -- 
> 2.7.4
>