blob: 2a790bea92c017e49a43b5ad858aeb429c67683d [file] [log] [blame]
From 89dd2e1e7d9988be2793b491259faed2b5892237 Mon Sep 17 00:00:00 2001
From: Andrei Dulea <>
Date: Fri, 13 Sep 2019 16:42:29 +0200
Subject: [PATCH] iommu/amd: Fix downgrading default page-sizes in alloc_pte()
commit 6ccb72f8374e17d60b58a7bfd5570496332c54e2 upstream.
Downgrading an existing large mapping to a mapping using smaller
page-sizes works only for the mappings created with page-mode 7 (i.e.
non-default page size).
Treat large mappings created with page-mode 0 (i.e. default page size)
like a non-present mapping and allow to overwrite it in alloc_pte().
While around, make sure that we flush the TLB only if we change an
existing mapping, otherwise we might end up acting on garbage PTEs.
Fixes: 6d568ef9a622 ("iommu/amd: Allow downgrading page-sizes in alloc_pte()")
Signed-off-by: Andrei Dulea <>
Signed-off-by: Paul Gortmaker <>
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index a0b64c43257a..909a97da6595 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1480,6 +1480,7 @@ static u64 *alloc_pte(struct protection_domain *domain,
pte_level = PM_PTE_LEVEL(__pte);
if (!IOMMU_PTE_PRESENT(__pte) ||
+ pte_level == PAGE_MODE_NONE ||
pte_level == PAGE_MODE_7_LEVEL) {
page = (u64 *)get_zeroed_page(gfp);
if (!page)
@@ -1490,7 +1491,7 @@ static u64 *alloc_pte(struct protection_domain *domain,
/* pte could have been changed somewhere. */
if (cmpxchg64(pte, __pte, __npte) != __pte)
free_page((unsigned long)page);
- else if (pte_level == PAGE_MODE_7_LEVEL)
+ else if (IOMMU_PTE_PRESENT(__pte))
domain->updated = true;