iommu/amd: Introduce iommu_dev_data.max_pasids

This variable will track the number of PASIDs supported by the device.
If IOMMU or device doesn't support PASID then it will be zero.

This will be used while allocating GCR3 table to decide required number
of PASID table levels. Also in PASID bind path it will use this variable
to check whether device supports PASID or not.

Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20240418103400.6229-7-vasant.hegde@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: hegdevasant

drivers/iommu/amd/amd_iommu_types.h

@@ -813,6 +813,7 @@ struct iommu_dev_data {
 	struct device *dev;
 	u16 devid;			  /* PCI Device ID */
 
+	u32 max_pasids;			  /* Max supported PASIDs */
 	u32 flags;			  /* Holds AMD_IOMMU_DEVICE_FLAG_<*> */
 	int ats_qdep;
 	u8 ats_enabled  :1;		  /* ATS state */

drivers/iommu/amd/iommu.c

@@ -2104,6 +2104,7 @@ static struct iommu_device *amd_iommu_probe_device(struct device *dev)
 {
 	struct iommu_device *iommu_dev;
 	struct amd_iommu *iommu;
+	struct iommu_dev_data *dev_data;
 	int ret;
 
 	if (!check_device(dev))
@@ -2130,6 +2131,17 @@ static struct iommu_device *amd_iommu_probe_device(struct device *dev)
 		iommu_dev = &iommu->iommu;
 	}
 
+	/*
+	 * If IOMMU and device supports PASID then it will contain max
+	 * supported PASIDs, else it will be zero.
+	 */
+	dev_data = dev_iommu_priv_get(dev);
+	if (amd_iommu_pasid_supported() && dev_is_pci(dev) &&
+	    pdev_pasid_supported(dev_data)) {
+		dev_data->max_pasids = min_t(u32, iommu->iommu.max_pasids,
+					     pci_max_pasids(to_pci_dev(dev)));
+	}
+
 	iommu_completion_wait(iommu);
 
 	return iommu_dev;