iommu/vt-d: Fix checks and print in pgtable_walk()

[ Upstream commit f1645676f25d2c846798f0233c3a953efd62aafb ]

There are some issues in pgtable_walk():

1. Super page is dumped as non-present page
2. dma_pte_superpage() should not check against leaf page table entries
3. Pointer pte is never NULL so checking it is meaningless
4. When an entry is not present, it still makes sense to dump the entry
   content.

Fix 1,2 by checking dma_pte_superpage()'s returned value after level check.
Fix 3 by removing pte check.
Fix 4 by checking present bit after printing.

By this chance, change to print "page table not present" instead of "PTE
not present" to be clearer.

Fixes: 914ff7719e8a ("iommu/vt-d: Dump DMAR translation structure when DMA fault occurs")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Link: https://lore.kernel.org/r/20241024092146.715063-3-zhenzhong.duan@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 8e56df584d3f4edbce6e0224c56308c6455e608f..cdb8701a968fdbe67292f95d6e86058d57b1d719 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -722,14 +722,15 @@ static void pgtable_walk(struct intel_iommu *iommu, unsigned long pfn,
        while (1) {
                offset = pfn_level_offset(pfn, level);
                pte = &parent[offset];
-               if (!pte || (dma_pte_superpage(pte) || !dma_pte_present(pte))) {
-                       pr_info("PTE not present at level %d\n", level);
-                       break;
-               }
 
                pr_info("pte level: %d, pte value: 0x%016llx\n", level, pte->val);
 
-               if (level == 1)
+               if (!dma_pte_present(pte)) {
+                       pr_info("page table not present at level %d\n", level - 1);
+                       break;
+               }
+
+               if (level == 1 || dma_pte_superpage(pte))
                        break;
 
                parent = phys_to_virt(dma_pte_addr(pte));