spapr_pci: Warn when RAM page size is not enabled in IOMMU page mask

If a page size used by QEMU is not enabled in the PHB IOMMU page mask,
in-kernel acceleration of TCE handling won't be enabled and performance
might be slower than expected.

This prints a warning if system page size is not enabled. This should
print a warning if huge pages are enabled but sphb.pgsz still uses
the default value of 4K|64K.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 98c52e411f17cf011e2be31fa2f30ac0463a7013..097ebdd51dfdd2bef5abec1d4383bf135a70cce2 100644 (file)
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1771,6 +1771,12 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
     }
 
     /* DMA setup */
+    if ((sphb->page_size_mask & qemu_getrampagesize()) == 0) {
+        error_report("System page size 0x%lx is not enabled in page_size_mask "
+                     "(0x%"PRIx64"). Performance may be slow",
+                     qemu_getrampagesize(), sphb->page_size_mask);
+    }
+
     for (i = 0; i < windows_supported; ++i) {
         tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn[i]);
         if (!tcet) {