intel-iommu: fix superpage support in pfn_to_dma_pte()

If target_level == 0, current code breaks out of the while-loop if
SUPERPAGE bit is set. We should also break out if PTE is not present.
If we don't do this, KVM calls to iommu_iova_to_phys() will cause
pfn_to_dma_pte() to create mapping for 4KiB pages.

Signed-off-by: Allen Kay <allen.m.kay@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 8 insertions, 9 deletions

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index e5883602cb35..a88f3cbb100b 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -306,6 +306,11 @@ static inline bool dma_pte_present(struct dma_pte *pte)
         return (pte->val & 3) != 0;
 }
 
+static inline bool dma_pte_superpage(struct dma_pte *pte)
+{
+        return (pte->val & (1 << 7));
+}
+
 static inline int first_pte_in_page(struct dma_pte *pte)
 {
         return !((unsigned long)pte & ~VTD_PAGE_MASK);
@@ -734,29 +739,23 @@ out:
 }
 
 static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain,
-                                      unsigned long pfn, int large_level)
+                                      unsigned long pfn, int target_level)
 {
         int addr_width = agaw_to_width(domain->agaw) - VTD_PAGE_SHIFT;
         struct dma_pte *parent, *pte = NULL;
         int level = agaw_to_level(domain->agaw);
-        int offset, target_level;
+        int offset;
 
         BUG_ON(!domain->pgd);
         BUG_ON(addr_width < BITS_PER_LONG && pfn >> addr_width);
         parent = domain->pgd;
 
-        /* Search pte */
-        if (!large_level)
-                target_level = 1;
-        else
-                target_level = large_level;
-
         while (level > 0) {
                 void *tmp_page;
 
                 offset = pfn_level_offset(pfn, level);
                 pte = &parent[offset];
-                if (!large_level && (pte->val & DMA_PTE_LARGE_PAGE))
+                if (!target_level && (dma_pte_superpage(pte) || !dma_pte_present(pte)))
                         break;
                 if (level == target_level)
                         break;