intel-iommu: Fix intel_iommu_unmap_range() with size 0

After some API change, intel_iommu_unmap_range() introduced a assumption that
parameter size != 0, otherwise the dma_pte_clean_range() would have a
overflowed argument. But the user like KVM don't have this assumption before,
then some BUG() triggered.

Fix it by ignoring size = 0.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 360fb67a30d7..ebc9b8dca881 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -3600,6 +3600,9 @@ static void intel_iommu_unmap_range(struct iommu_domain *domain,
 {
         struct dmar_domain *dmar_domain = domain->priv;
 
+        if (!size)
+                return;
+
         dma_pte_clear_range(dmar_domain, iova >> VTD_PAGE_SHIFT,
                             (iova + size - 1) >> VTD_PAGE_SHIFT);