iommu/amd: Fix logic to determine and checking max PASID

In reality, the spec can only support 16-bit PASID since
INVALIDATE_IOTLB_PAGES and COMPLETE_PPR_REQUEST commands only allow 16-bit
PASID. So, we updated the PASID_MASK accordingly and invoke BUG_ON
if the hardware is reporting PASmax more than 16-bit.

Besides, max PASID is defined as ((2^(PASmax+1)) - 1). The current does not
determine this correctly.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Tested-by: Jay Cornwall <Jay.Cornwall@amd.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>

3 files changed, 19 insertions, 12 deletions

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 1dd9f818fc84..c949520bd196 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -963,7 +963,7 @@ static void build_inv_iommu_pasid(struct iommu_cmd *cmd, u16 domid, int pasid,
 
         address &= ~(0xfffULL);
 
-        cmd->data[0]  = pasid & PASID_MASK;
+        cmd->data[0]  = pasid;
         cmd->data[1]  = domid;
         cmd->data[2]  = lower_32_bits(address);
         cmd->data[3]  = upper_32_bits(address);
@@ -1001,7 +1001,7 @@ static void build_complete_ppr(struct iommu_cmd *cmd, u16 devid, int pasid,
 
         cmd->data[0]  = devid;
         if (gn) {
-                cmd->data[1]  = pasid & PASID_MASK;
+                cmd->data[1]  = pasid;
                 cmd->data[2]  = CMD_INV_IOMMU_PAGES_GN_MASK;
         }
         cmd->data[3]  = tag & 0x1ff;
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 28b4bea7c109..b76c58dbe30c 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -150,7 +150,7 @@ 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;
+u32 amd_iommu_max_pasid __read_mostly = ~0;
 
 bool amd_iommu_v2_present __read_mostly;
 bool amd_iommu_pc_present __read_mostly;
@@ -1231,14 +1231,16 @@ static int iommu_init_pci(struct amd_iommu *iommu)
 
         if (iommu_feature(iommu, FEATURE_GT)) {
                 int glxval;
-                u32 pasids;
-                u64 shift;
+                u32 max_pasid;
+                u64 pasmax;
 
-                shift   = iommu->features & FEATURE_PASID_MASK;
-                shift >>= FEATURE_PASID_SHIFT;
-                pasids  = (1 << shift);
+                pasmax = iommu->features & FEATURE_PASID_MASK;
+                pasmax >>= FEATURE_PASID_SHIFT;
+                max_pasid  = (1 << (pasmax + 1)) - 1;
 
-                amd_iommu_max_pasids = min(amd_iommu_max_pasids, pasids);
+                amd_iommu_max_pasid = min(amd_iommu_max_pasid, max_pasid);
+
+                BUG_ON(amd_iommu_max_pasid & ~PASID_MASK);
 
                 glxval   = iommu->features & FEATURE_GLXVAL_MASK;
                 glxval >>= FEATURE_GLXVAL_SHIFT;
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index e400fbe411de..55ba46bdb01b 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -98,7 +98,12 @@
 #define FEATURE_GLXVAL_SHIFT    14
 #define FEATURE_GLXVAL_MASK     (0x03ULL << FEATURE_GLXVAL_SHIFT)
 
-#define PASID_MASK              0x000fffff
+/* Note:
+ * The current driver only support 16-bit PASID.
+ * Currently, hardware only implement upto 16-bit PASID
+ * even though the spec says it could have upto 20 bits.
+ */
+#define PASID_MASK              0x0000ffff
 
 /* MMIO status bits */
 #define MMIO_STATUS_EVT_INT_MASK        (1 << 1)
@@ -696,8 +701,8 @@ extern unsigned long *amd_iommu_pd_alloc_bitmap;
  */
 extern u32 amd_iommu_unmap_flush;
 
-/* Smallest number of PASIDs supported by any IOMMU in the system */
-extern u32 amd_iommu_max_pasids;
+/* Smallest max PASID supported by any IOMMU in the system */
+extern u32 amd_iommu_max_pasid;
 
 extern bool amd_iommu_v2_present;