linux-kernel - RE: [PATCH RFC v2 01/11] iommu: Add pasid_bits field in struct dev

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Message-ID: <BN9PR11MB52763DAEC605FD1B21EE4EAF8C1F9@BN9PR11MB5276.namprd11.prod.outlook.com>
Date:   Wed, 30 Mar 2022 07:05:23 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        "Raj, Ashok" <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        "Robin Murphy" <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>
CC:     Eric Auger <eric.auger@...hat.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH RFC v2 01/11] iommu: Add pasid_bits field in struct
 dev_iommu

> From: Lu Baolu <baolu.lu@...ux.intel.com>
> Sent: Tuesday, March 29, 2022 1:38 PM
> 
> Use this field to save the pasid/ssid bits that a device is able to
> support with its IOMMU hardware. It is a generic attribute of a device
> and lifting it into the per-device dev_iommu struct makes it possible
> to allocate a PASID for device without calls into the IOMMU drivers.
> Any iommu driver which suports PASID related features should set this
> field before features are enabled on the devices.

Miss a clarification for non-PCI SVA as discussed here:

https://lore.kernel.org/all/85d61ad6-0cf0-ac65-3312-32d0cdeb1b27@linux.intel.com/


> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  include/linux/iommu.h                       | 1 +
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 ++
>  drivers/iommu/intel/iommu.c                 | 5 ++++-
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 6ef2df258673..36f43af0af53 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -368,6 +368,7 @@ struct dev_iommu {
>  	struct iommu_fwspec		*fwspec;
>  	struct iommu_device		*iommu_dev;
>  	void				*priv;
> +	unsigned int			pasid_bits;
>  };
> 
>  int iommu_device_register(struct iommu_device *iommu,
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 627a3ed5ee8f..afc63fce6107 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2681,6 +2681,8 @@ static struct iommu_device
> *arm_smmu_probe_device(struct device *dev)
>  	    smmu->features & ARM_SMMU_FEAT_STALL_FORCE)
>  		master->stall_enabled = true;
> 
> +	dev->iommu->pasid_bits = master->ssid_bits;
> +
>  	return &smmu->iommu;
> 
>  err_free_master:
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 6f7485c44a4b..c1b91bce1530 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4587,8 +4587,11 @@ static struct iommu_device
> *intel_iommu_probe_device(struct device *dev)
>  			if (pasid_supported(iommu)) {
>  				int features = pci_pasid_features(pdev);
> 
> -				if (features >= 0)
> +				if (features >= 0) {
>  					info->pasid_supported = features | 1;
> +					dev->iommu->pasid_bits =
> +						fls(pci_max_pasids(pdev)) - 1;
> +				}
>  			}
> 
>  			if (info->ats_supported && ecap_prs(iommu->ecap)
> &&
> --
> 2.25.1