iommu/tegra-smmu: Fix iova_to_phys() method
iova_to_phys() has several problems:
(a) iova_to_phys() is supposed to return 0 if there is no entry present
for the iova.
(b) if as_get_pte() fails, we oops the kernel by dereferencing a NULL
pointer. Really, we should not even be trying to allocate a page
table at all, but should only be returning the presence of the 2nd
level page table. This will be fixed in a subsequent patch.
Treat both of these conditions as "no mapping" conditions.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index c1f2e52..0833549 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -592,6 +592,9 @@
u32 *pte;
pte = as_get_pte(as, iova, &page);
+ if (!pte || !*pte)
+ return 0;
+
pfn = *pte & as->smmu->pfn_mask;
return PFN_PHYS(pfn);