intel-iommu: Don't keep freeing page zero in dma_pte_free_pagetable()

Check dma_pte_present() and only free the page if there _is_ one.
Kind of surprising that there was no warning about this.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index dcf0295a9b60..53075424a434 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -826,8 +826,10 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain,
                                 continue;
                         }
                         do {
-                                free_pgtable_page(phys_to_virt(dma_pte_addr(pte)));
-                                dma_clear_pte(pte);
+                                if (dma_pte_present(pte)) {
+                                        free_pgtable_page(phys_to_virt(dma_pte_addr(pte)));
+                                        dma_clear_pte(pte);
+                                }
                                 pte++;
                                 tmp += level_size(level);
                         } while (!first_pte_in_page(pte) &&