diff --git a/xen/drivers/passthrough/vtd/iommu.c b/xen/drivers/passthrough/vtd/iommu.c
index 26401c7e64..77cdc21837 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -570,13 +570,14 @@ static int __must_check iommu_flush_iotlb(struct domain *d, dfn_t dfn,
         if ( iommu_domid == -1 )
             continue;
 
-        if ( page_count != 1 || dfn_eq(dfn, INVALID_DFN) )
+        if ( !page_count || (page_count & (page_count - 1)) ||
+             dfn_eq(dfn, INVALID_DFN) || !IS_ALIGNED(dfn_x(dfn), page_count) )
             rc = iommu_flush_iotlb_dsi(iommu, iommu_domid,
                                        0, flush_dev_iotlb);
         else
             rc = iommu_flush_iotlb_psi(iommu, iommu_domid,
                                        dfn_to_daddr(dfn),
-                                       PAGE_ORDER_4K,
+                                       get_order_from_pages(page_count),
                                        !dma_old_pte_present,
                                        flush_dev_iotlb);