linux-kernel - Re: [PATCH v3 1/1] PCI/ATS: Check PRI supported on the PF device when SRIOV is enabled

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Date:   Thu, 23 Jul 2020 18:54:45 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Ashok Raj <ashok.raj@...el.com>
Cc:     linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Joerg Roedel <joro@...tes.org>, Lu Baolu <baolu.lu@...el.com>,
        stable@...r.kernel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org
Subject: Re: [PATCH v3 1/1] PCI/ATS: Check PRI supported on the PF device
 when SRIOV is enabled

On Thu, Jul 23, 2020 at 03:37:29PM -0700, Ashok Raj wrote:
> PASID and PRI capabilities are only enumerated in PF devices. VF devices
> do not enumerate these capabilites. IOMMU drivers also need to enumerate
> them before enabling features in the IOMMU. Extending the same support as
> PASID feature discovery (pci_pasid_features) for PRI.
> 
> Fixes: b16d0cb9e2fc ("iommu/vt-d: Always enable PASID/PRI PCI capabilities before ATS")
> Signed-off-by: Ashok Raj <ashok.raj@...el.com>

This looks right to me, but I would like Joerg's ack before applying
it.

> To: Bjorn Helgaas <bhelgaas@...gle.com>
> To: Joerg Roedel <joro@...tes.com>
> To: Lu Baolu <baolu.lu@...el.com>
> Cc: stable@...r.kernel.org
> Cc: linux-pci@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: Ashok Raj <ashok.raj@...el.com>
> Cc: iommu@...ts.linux-foundation.org
> ---
> v3: Added Fixes tag
> v2: Fixed build failure reported from lkp when CONFIG_PRI=n
> 
>  drivers/iommu/intel/iommu.c |  2 +-
>  drivers/pci/ats.c           | 13 +++++++++++++
>  include/linux/pci-ats.h     |  4 ++++
>  3 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index d759e7234e98..276452f5e6a7 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -2560,7 +2560,7 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
>  			}
>  
>  			if (info->ats_supported && ecap_prs(iommu->ecap) &&
> -			    pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI))
> +			    pci_pri_supported(pdev))
>  				info->pri_supported = 1;
>  		}
>  	}
> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
> index b761c1f72f67..2e6cf0c700f7 100644
> --- a/drivers/pci/ats.c
> +++ b/drivers/pci/ats.c
> @@ -325,6 +325,19 @@ int pci_prg_resp_pasid_required(struct pci_dev *pdev)
>  
>  	return pdev->pasid_required;
>  }
> +
> +/**
> + * pci_pri_supported - Check if PRI is supported.
> + * @pdev: PCI device structure
> + *
> + * Returns true if PRI capability is present, false otherwise.
> + */
> +bool pci_pri_supported(struct pci_dev *pdev)
> +{
> +	/* VFs share the PF PRI configuration */
> +	return !!(pci_physfn(pdev)->pri_cap);
> +}
> +EXPORT_SYMBOL_GPL(pci_pri_supported);
>  #endif /* CONFIG_PCI_PRI */
>  
>  #ifdef CONFIG_PCI_PASID
> diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h
> index f75c307f346d..df54cd5b15db 100644
> --- a/include/linux/pci-ats.h
> +++ b/include/linux/pci-ats.h
> @@ -28,6 +28,10 @@ int pci_enable_pri(struct pci_dev *pdev, u32 reqs);
>  void pci_disable_pri(struct pci_dev *pdev);
>  int pci_reset_pri(struct pci_dev *pdev);
>  int pci_prg_resp_pasid_required(struct pci_dev *pdev);
> +bool pci_pri_supported(struct pci_dev *pdev);
> +#else
> +static inline bool pci_pri_supported(struct pci_dev *pdev)
> +{ return false; }
>  #endif /* CONFIG_PCI_PRI */
>  
>  #ifdef CONFIG_PCI_PASID
> -- 
> 2.7.4
>