spapr: Make ibm, change-msi respect 3 return values

Currently, rtas_ibm_change_msi() always returns four values even if
less are specified.

Correct this by only returning the fourth parameter if it was
requested.

This is specified by PAPR.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
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 a2feb4c..6782fd0 100644 (file)
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -375,7 +375,9 @@ out:
     rtas_st(rets, 0, RTAS_OUT_SUCCESS);
     rtas_st(rets, 1, req_num);
     rtas_st(rets, 2, ++seq_num);
-    rtas_st(rets, 3, ret_intr_type);
+    if (nret > 3) {
+        rtas_st(rets, 3, ret_intr_type);
+    }
 
     trace_spapr_pci_rtas_ibm_change_msi(config_addr, func, req_num, irq);
 }