iommu/amd: Allow downgrading page-sizes in alloc_pte()

Before this patch it was not possible the downgrade a
mapping established with page-mode 7 to a mapping using
smaller page-sizes, because the pte_level != level check
prevented that.

Treat page-mode 7 like a non-present mapping and allow to
overwrite it in alloc_pte().

Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 49b5d31..6a88ba9 100644 (file)
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1460,10 +1460,13 @@ static u64 *alloc_pte(struct protection_domain *domain,
 
        while (level > end_lvl) {
                u64 __pte, __npte;
+               int pte_level;
 
-               __pte = *pte;
+               __pte     = *pte;
+               pte_level = PM_PTE_LEVEL(__pte);
 
-               if (!IOMMU_PTE_PRESENT(__pte)) {
+               if (!IOMMU_PTE_PRESENT(__pte) ||
+                   pte_level == PAGE_MODE_7_LEVEL) {
                        page = (u64 *)get_zeroed_page(gfp);
                        if (!page)
                                return NULL;
@@ -1475,10 +1478,13 @@ static u64 *alloc_pte(struct protection_domain *domain,
                                free_page((unsigned long)page);
                                continue;
                        }
+
+                       if (pte_level == PAGE_MODE_7_LEVEL)
+                               domain->updated = true;
                }
 
                /* No level skipping support yet */
-               if (PM_PTE_LEVEL(*pte) != level)
+               if (pte_level != level)
                        return NULL;
 
                level -= 1;