diff --git a/drivers/parisc/sba_iommu.c b/drivers/parisc/sba_iommu.c
index de8e4e347249..e410033b6df0 100644
--- a/drivers/parisc/sba_iommu.c
+++ b/drivers/parisc/sba_iommu.c
@@ -1270,7 +1270,7 @@ sba_ioc_init_pluto(struct parisc_device *sba, struct ioc *ioc, int ioc_num)
 	** (one that doesn't overlap memory or LMMIO space) in the
 	** IBASE and IMASK registers.
 	*/
-	ioc->ibase = READ_REG(ioc->ioc_hpa + IOC_IBASE);
+	ioc->ibase = READ_REG(ioc->ioc_hpa + IOC_IBASE) & ~0x1fffffULL;
 	iova_space_size = ~(READ_REG(ioc->ioc_hpa + IOC_IMASK) & 0xFFFFFFFFUL) + 1;
 
 	if ((ioc->ibase < 0xfed00000UL) && ((ioc->ibase + iova_space_size) > 0xfee00000UL)) {