vTPM: get the buffer allocated for event log instead of the actual log

The OS should ask Power Firmware (PFW) for the size of the buffer
allocated for the event log, instead of the size of the actual
event log.  It then passes the buffer adddress and size to PFW in
the handover process, into which PFW copies the log.
Signed-off-by: Hon Ching(Vicky) Lo <honclo@linux.vnet.ibm.com>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>

arch/powerpc/kernel/prom_init.c

@@ -1450,14 +1450,21 @@ static void __init prom_instantiate_sml(void)
 			prom_printf("Reformat SML to EFI alignment failed\n");
 			return;
 		}
-	}
 
+		if (call_prom_ret("call-method", 2, 2, &size,
+				  ADDR("sml-get-allocated-size"),
+				  ibmvtpm_inst) != 0 || size == 0) {
+			prom_printf("SML get allocated size failed\n");
+			return;
+		}
+	} else {
 		if (call_prom_ret("call-method", 2, 2, &size,
 				  ADDR("sml-get-handover-size"),
 				  ibmvtpm_inst) != 0 || size == 0) {
 			prom_printf("SML get handover size failed\n");
 			return;
 		}
+	}
 
 	base = alloc_down(size, PAGE_SIZE, 0);
 	if (base == 0)
@@ -1465,6 +1472,8 @@ static void __init prom_instantiate_sml(void)
 
 	prom_printf("instantiating sml at 0x%x...", base);
 
+	memset((void *)base, 0, size);
+
 	if (call_prom_ret("call-method", 4, 2, &entry,
 			  ADDR("sml-handover"),
 			  ibmvtpm_inst, size, base) != 0 || entry == 0) {