iommu/amd: Get the maximum number of PASIDs supported

Read the number of PASIDs supported by each IOMMU in the
system and take the smallest number as the maximum value
supported by the IOMMU driver.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

drivers/iommu/amd_iommu_init.c

@@ -141,6 +141,8 @@ int amd_iommus_present;
 bool amd_iommu_np_cache __read_mostly;
 bool amd_iommu_iotlb_sup __read_mostly = true;
 
+u32 amd_iommu_max_pasids __read_mostly = ~0;
+
 /*
  * The ACPI table parsing functions set this variable on an error
  */
@@ -699,6 +701,17 @@ static void __init init_iommu_from_pci(struct amd_iommu *iommu)
 
 	iommu->features = ((u64)high << 32) | low;
 
+	if (iommu_feature(iommu, FEATURE_GT)) {
+		u32 pasids;
+		u64 shift;
+
+		shift   = iommu->features & FEATURE_PASID_MASK;
+		shift >>= FEATURE_PASID_SHIFT;
+		pasids  = (1 << shift);
+
+		amd_iommu_max_pasids = min(amd_iommu_max_pasids, pasids);
+	}
+
 	if (!is_rd890_iommu(iommu->dev))
 		return;
 

drivers/iommu/amd_iommu_types.h

@@ -87,6 +87,9 @@
 #define FEATURE_HE		(1ULL<<8)
 #define FEATURE_PC		(1ULL<<9)
 
+#define FEATURE_PASID_SHIFT	32
+#define FEATURE_PASID_MASK	(0x1fULL << FEATURE_PASID_SHIFT)
+
 /* MMIO status bits */
 #define MMIO_STATUS_COM_WAIT_INT_MASK	0x04
 
@@ -549,6 +552,9 @@ extern unsigned long *amd_iommu_pd_alloc_bitmap;
  */
 extern bool amd_iommu_unmap_flush;
 
+/* Smallest number of PASIDs supported by any IOMMU in the system */
+extern u32 amd_iommu_max_pasids;
+
 /* takes bus and device/function and returns the device id
  * FIXME: should that be in generic PCI code? */
 static inline u16 calc_devid(u8 bus, u8 devfn)