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...@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;
 };
 
 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

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