Re: [RFC PATCH 18/30] PCI: Make "PRG Response PASID Required" handling common

[Bjorn Helgaas <helgaas@kernel.org>]

On Mon, Feb 27, 2017 at 07:54:29PM +0000, Jean-Philippe Brucker wrote:
> The PASID ECN to the PCIe spec added a bit in the PRI status register that
> allows a Function to declare whether a PRG Response should contain the
> PASID prefix or not.
> 
> Move the helper that accesses it from amd_iommu into the PCI subsystem,
> renaming it to something more consistent with the spec, and introducing
> another obscure acronym to make it all fit.

Maybe mention the acronym itelf and spell it out here?

> Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  drivers/iommu/amd_iommu.c     | 19 +------------------
>  drivers/pci/ats.c             | 17 +++++++++++++++++
>  include/linux/pci-ats.h       |  8 ++++++++
>  include/uapi/linux/pci_regs.h |  1 +
>  4 files changed, 27 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> index 98940d1392cb..c5c598bf4ba3 100644
> --- a/drivers/iommu/amd_iommu.c
> +++ b/drivers/iommu/amd_iommu.c
> @@ -2024,23 +2024,6 @@ static int pdev_iommuv2_enable(struct pci_dev *pdev)
>  	return ret;
>  }
>  
> -/* FIXME: Move this to PCI code */
> -#define PCI_PRI_TLP_OFF		(1 << 15)
> -
> -static bool pci_pri_tlp_required(struct pci_dev *pdev)
> -{
> -	u16 status;
> -	int pos;
> -
> -	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
> -	if (!pos)
> -		return false;
> -
> -	pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status);
> -
> -	return (status & PCI_PRI_TLP_OFF) ? true : false;
> -}
> -
>  /*
>   * If a device is not yet associated with a domain, this function
>   * assigns it visible for the hardware
> @@ -2069,7 +2052,7 @@ static int attach_device(struct device *dev,
>  
>  			dev_data->ats.enabled = true;
>  			dev_data->ats.qdep    = pci_ats_queue_depth(pdev);
> -			dev_data->pri_tlp     = pci_pri_tlp_required(pdev);
> +			dev_data->pri_tlp     = pci_prg_resp_requires_prefix(pdev);
>  		}
>  	} else if (amd_iommu_iotlb_sup &&
>  		   pci_enable_ats(pdev, PAGE_SHIFT) == 0) {
> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
> index eeb9fb2b47aa..331376e9bb8b 100644
> --- a/drivers/pci/ats.c
> +++ b/drivers/pci/ats.c
> @@ -334,3 +334,20 @@ int pci_max_pasids(struct pci_dev *pdev)
>  }
>  EXPORT_SYMBOL_GPL(pci_max_pasids);
>  #endif /* CONFIG_PCI_PASID */
> +
> +#if defined(CONFIG_PCI_PASID) && defined(CONFIG_PCI_PRI)
> +bool pci_prg_resp_requires_prefix(struct pci_dev *pdev)
> +{
> +	u16 status;
> +	int pos;
> +
> +	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
> +	if (!pos)
> +		return false;
> +
> +	pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status);
> +
> +	return !!(status & PCI_PRI_STATUS_PRPR);
> +}
> +EXPORT_SYMBOL_GPL(pci_prg_resp_requires_prefix);
> +#endif /* CONFIG_PCI_PASID && CONFIG_PCI_PRI */
> diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h
> index 57e0b8250947..e21bcacbe80c 100644
> --- a/include/linux/pci-ats.h
> +++ b/include/linux/pci-ats.h
> @@ -57,5 +57,13 @@ static inline int pci_max_pasids(struct pci_dev *pdev)
>  
>  #endif /* CONFIG_PCI_PASID */
>  
> +#if defined(CONFIG_PCI_PASID) && defined(CONFIG_PCI_PRI)
> +bool pci_prg_resp_requires_prefix(struct pci_dev *pdev);
> +#else
> +static inline bool pci_prg_resp_requires_prefix(struct pci_dev *pdev)
> +{
> +	return false;
> +}
> +#endif /* CONFIG_PCI_PASID && CONFIG_PCI_PRI */
>  
>  #endif /* LINUX_PCI_ATS_H*/
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index 634c9c44ed6c..bae815876be6 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -864,6 +864,7 @@
>  #define  PCI_PRI_STATUS_RF	0x001	/* Response Failure */
>  #define  PCI_PRI_STATUS_UPRGI	0x002	/* Unexpected PRG index */
>  #define  PCI_PRI_STATUS_STOPPED	0x100	/* PRI Stopped */
> +#define  PCI_PRI_STATUS_PRPR	0x8000	/* PRG Response requires PASID prefix */
>  #define PCI_PRI_MAX_REQ		0x08	/* PRI max reqs supported */
>  #define PCI_PRI_ALLOC_REQ	0x0c	/* PRI max reqs allowed */
>  #define PCI_EXT_CAP_PRI_SIZEOF	16
> -- 
> 2.11.0
> 
> 
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