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SubjectRe: [PATCH RFC v2 01/11] iommu: Add pasid_bits field in struct dev_iommu
Hi BaoLu,

On Tue, 29 Mar 2022 13:37:50 +0800, Lu Baolu <baolu.lu@linux.intel.com>
wrote:

> 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.
>
> Signed-off-by: Lu Baolu <baolu.lu@linux.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;
pasid_width?
PCI spec uses "Max PASID Width"

> };
>
> 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)
> &&


Thanks,

Jacob

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