diff --git a/xen/drivers/passthrough/amd/iommu_cmd.c b/xen/drivers/passthrough/amd/iommu_cmd.c
index 665e882a2d..abfbdf2b28 100644
--- a/xen/drivers/passthrough/amd/iommu_cmd.c
+++ b/xen/drivers/passthrough/amd/iommu_cmd.c
@@ -212,7 +212,7 @@ static void invalidate_iotlb_pages(struct amd_iommu *iommu,
 
     set_field_in_reg_u32(sflag, 0,
                          IOMMU_INV_IOTLB_PAGES_S_FLAG_MASK,
-                         IOMMU_INV_IOTLB_PAGES_S_FLAG_MASK, &entry);
+                         IOMMU_INV_IOTLB_PAGES_S_FLAG_SHIFT, &entry);
 
     set_field_in_reg_u32((u32)addr_lo >> PAGE_SHIFT, entry,
                          IOMMU_INV_IOTLB_PAGES_ADDR_LOW_MASK,