From: Andrei Dulea adulea@amazon.de
[ Upstream commit 6ccb72f8374e17d60b58a7bfd5570496332c54e2 ]
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 adulea@amazon.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/amd_iommu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c index 61de81965c44e..0fb42a846404b 100644 --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -1490,6 +1490,7 @@ 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) @@ -1500,7 +1501,7 @@ 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;
continue;