[PATCH RFC 01/11] iommu: Add pasid_bits field in struct dev_iommu

[Lu Baolu]

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@xxxxxxxxxxxxxxx>
---
 include/linux/iommu.h                       | 1 +
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 1 +
 drivers/iommu/intel/iommu.c                 | 5 ++++-
 3 files changed, 6 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..8e262210b5ad 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2812,6 +2812,7 @@ static int arm_smmu_dev_enable_feature(struct device *dev,
 		master->iopf_enabled = true;
 		return 0;
 	case IOMMU_DEV_FEAT_SVA:
+		dev->iommu->pasid_bits = master->ssid_bits;
 		return arm_smmu_master_enable_sva(master);
 	default:
 		return -EINVAL;
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