RE: [PATCH 1/1] iommu/vt-d: Enable PASID during iommu device probe

["Tian, Kevin" <kevin.tian@intel.com>]

> From: Lu Baolu <baolu.lu@linux.intel.com>
> Sent: Monday, September 12, 2022 10:48 AM
>
> @@ -1401,7 +1403,6 @@ static void iommu_enable_dev_iotlb(struct
> device_domain_info *info)

This is not the right name now as dev_iotlb is only related to ATS.

>  		info->pfsid = pci_dev_id(pf_pdev);
>  	}
> 
> -#ifdef CONFIG_INTEL_IOMMU_SVM
>  	/* The PCIe spec, in its wisdom, declares that the behaviour of
>  	   the device if you enable PASID support after ATS support is
>  	   undefined. So always enable PASID support on devices which
> @@ -1414,7 +1415,7 @@ static void iommu_enable_dev_iotlb(struct
> device_domain_info *info)
>  	    (info->pasid_enabled ? pci_prg_resp_pasid_required(pdev) : 1)
> &&
>  	    !pci_reset_pri(pdev) && !pci_enable_pri(pdev, PRQ_DEPTH))
>  		info->pri_enabled = 1;
> -#endif
> +
>  	if (info->ats_supported && pci_ats_page_aligned(pdev) &&
>  	    !pci_enable_ats(pdev, VTD_PAGE_SHIFT)) {
>  		info->ats_enabled = 1;

iommu_enable_dev_iotlb() is currently called both when the device is probed
and when sva is enabled (which is actually useless). From this angle the commit
msg is inaccurate. 

> diff --git a/drivers/iommu/intel/Kconfig b/drivers/iommu/intel/Kconfig
> index 39a06d245f12..b3f40375f214 100644
> --- a/drivers/iommu/intel/Kconfig
> +++ b/drivers/iommu/intel/Kconfig
> @@ -21,6 +21,8 @@ config INTEL_IOMMU
>  	select IOASID
>  	select IOMMU_DMA
>  	select PCI_ATS
> +	select PCI_PRI
> +	select PCI_PASID
>  	help
>  	  DMA remapping (DMAR) devices support enables independent
> address
>  	  translations for Direct Memory Access (DMA) from devices.
> @@ -48,8 +50,6 @@ config INTEL_IOMMU_DEBUGFS
>  config INTEL_IOMMU_SVM
>  	bool "Support for Shared Virtual Memory with Intel IOMMU"
>  	depends on X86_64
> -	select PCI_PASID
> -	select PCI_PRI
>  	select MMU_NOTIFIER
>  	select IOASID

this is already selected by CONFIG_INTEL_IOMMU

>  	select IOMMU_SVA
> --
> 2.25.1