[Qemu-devel] [PATCH 3/4] spapr: Fix RTAS sysparm DIAGNOSTICS_RUN_MODE

[Sam Bobroff <sam.bobroff@au1.ibm.com>]

This allows the ibm,get-system-parameter RTAS call to succeed for the
DIAGNOSTICS_RUN_MODE system parameter.

The problem can be seen with "ppc64_cpu --run-mode" from the
powerpc-utils package which fails before this patch with "Machine does
not support diagnostic run mode".

This is corrected by using the rtas_st_buffer() function to write to
the buffer.

The function return value code is also slightly simplified.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
---
 hw/ppc/spapr_rtas.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index 4f87673..8d94845 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -236,19 +236,18 @@ static void rtas_ibm_get_system_parameter(PowerPCCPU *cpu,
     target_ulong parameter = rtas_ld(args, 0);
     target_ulong buffer = rtas_ld(args, 1);
     target_ulong length = rtas_ld(args, 2);
-    target_ulong ret = RTAS_OUT_NOT_SUPPORTED;
+    target_ulong ret = RTAS_OUT_SUCCESS;
+    uint8_t zero = 0;
 
     switch (parameter) {
     case DIAGNOSTICS_RUN_MODE:
-        if (length == 1) {
-            rtas_st(buffer, 0, 0);
-            ret = RTAS_OUT_SUCCESS;
-        }
+        rtas_st_buffer(buffer, length, &zero, sizeof zero);
         break;
     case UUID:
         rtas_st_buffer(buffer, length, qemu_uuid, (qemu_uuid_set ? 16 : 0));
-        ret = RTAS_OUT_SUCCESS;
         break;
+    default:
+        ret = RTAS_OUT_NOT_SUPPORTED;
     }
 
     rtas_st(rets, 0, ret);
-- 
1.9.0