linux-kernel - Re: [PATCH v5 3/7] iommu/vt-d: Introduce is_downstream_to_pci

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Message-ID: <560dde25-6cac-a721-baf1-110e03723eda@linux.intel.com>
Date:   Wed, 29 May 2019 10:11:48 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Eric Auger <eric.auger@...hat.com>, eric.auger.pro@...il.com,
        joro@...tes.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, dwmw2@...radead.org,
        robin.murphy@....com
Cc:     baolu.lu@...ux.intel.com, alex.williamson@...hat.com,
        shameerali.kolothum.thodi@...wei.com, jean-philippe.brucker@....com
Subject: Re: [PATCH v5 3/7] iommu/vt-d: Introduce is_downstream_to_pci_bridge
 helper

Hi,

On 5/28/19 7:50 PM, Eric Auger wrote:
> Several call sites are about to check whether a device belongs
> to the PCI sub-hierarchy of a candidate PCI-PCI bridge.
> Introduce an helper to perform that check.
> 

This looks good to me.

Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>

Best regards,
Baolu


> Signed-off-by: Eric Auger <eric.auger@...hat.com>
> ---
>   drivers/iommu/intel-iommu.c | 37 +++++++++++++++++++++++++++++--------
>   1 file changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 5ec8b5bd308f..879f11c82b05 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -736,12 +736,39 @@ static int iommu_dummy(struct device *dev)
>   	return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
>   }
>   
> +/* is_downstream_to_pci_bridge - test if a device belongs to the
> + * PCI sub-hierarchy of a candidate PCI-PCI bridge
> + *
> + * @dev: candidate PCI device belonging to @bridge PCI sub-hierarchy
> + * @bridge: the candidate PCI-PCI bridge
> + *
> + * Return: true if @dev belongs to @bridge PCI sub-hierarchy
> + */
> +static bool
> +is_downstream_to_pci_bridge(struct device *dev, struct device *bridge)
> +{
> +	struct pci_dev *pdev, *pbridge;
> +
> +	if (!dev_is_pci(dev) || !dev_is_pci(bridge))
> +		return false;
> +
> +	pdev = to_pci_dev(dev);
> +	pbridge = to_pci_dev(bridge);
> +
> +	if (pbridge->subordinate &&
> +	    pbridge->subordinate->number <= pdev->bus->number &&
> +	    pbridge->subordinate->busn_res.end >= pdev->bus->number)
> +		return true;
> +
> +	return false;
> +}
> +
>   static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn)
>   {
>   	struct dmar_drhd_unit *drhd = NULL;
>   	struct intel_iommu *iommu;
>   	struct device *tmp;
> -	struct pci_dev *ptmp, *pdev = NULL;
> +	struct pci_dev *pdev = NULL;
>   	u16 segment = 0;
>   	int i;
>   
> @@ -787,13 +814,7 @@ static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devf
>   				goto out;
>   			}
>   
> -			if (!pdev || !dev_is_pci(tmp))
> -				continue;
> -
> -			ptmp = to_pci_dev(tmp);
> -			if (ptmp->subordinate &&
> -			    ptmp->subordinate->number <= pdev->bus->number &&
> -			    ptmp->subordinate->busn_res.end >= pdev->bus->number)
> +			if (is_downstream_to_pci_bridge(dev, tmp))
>   				goto got_pdev;
>   		}
>   
>