spapr: Fix RTAS sysparm DIAGNOSTICS_RUN_MODE

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 RTAS constants are also moved out into a header file, some new
constants added and the surrounding code slightly simplified.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
[agraf: remove some commentary]
Signed-off-by: Alexander Graf <agraf@suse.de>

2 files changed, 20 insertions, 9 deletions

diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index 4e87d02805..ac9a8601ea 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -222,8 +222,6 @@ static void rtas_stop_self(PowerPCCPU *cpu, sPAPREnvironment *spapr,
     env->msr = 0;
 }
 
-#define DIAGNOSTICS_RUN_MODE        42
-
 static void rtas_ibm_get_system_parameter(PowerPCCPU *cpu,
                                           sPAPREnvironment *spapr,
                                           uint32_t token, uint32_t nargs,
@@ -233,16 +231,18 @@ 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;
 
     switch (parameter) {
-    case DIAGNOSTICS_RUN_MODE:
-        if (length == 1) {
-            rtas_st(buffer, 0, 0);
-            ret = RTAS_OUT_SUCCESS;
-        }
+    case RTAS_SYSPARM_DIAGNOSTICS_RUN_MODE: {
+        uint8_t param_val = DIAGNOSTICS_RUN_MODE_DISABLED;
+
+        rtas_st_buffer(buffer, length, &param_val, sizeof(param_val));
         break;
     }
+    default:
+        ret = RTAS_OUT_NOT_SUPPORTED;
+    }
 
     rtas_st(rets, 0, ret);
 }
@@ -257,7 +257,7 @@ static void rtas_ibm_set_system_parameter(PowerPCCPU *cpu,
     target_ulong ret = RTAS_OUT_NOT_SUPPORTED;
 
     switch (parameter) {
-    case DIAGNOSTICS_RUN_MODE:
+    case RTAS_SYSPARM_DIAGNOSTICS_RUN_MODE:
         ret = RTAS_OUT_NOT_AUTHORIZED;
         break;
     }
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 25ca87f244..d043771616 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -397,6 +397,17 @@ static inline int spapr_allocate_lsi(int hint)
 
 #define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x21)
 
+/* RTAS ibm,get-system-parameter token values */
+#define RTAS_SYSPARM_DIAGNOSTICS_RUN_MODE        42
+
+/* Possible values for the platform-processor-diagnostics-run-mode parameter
+ * of the RTAS ibm,get-system-parameter call.
+ */
+#define DIAGNOSTICS_RUN_MODE_DISABLED  0
+#define DIAGNOSTICS_RUN_MODE_STAGGERED 1
+#define DIAGNOSTICS_RUN_MODE_IMMEDIATE 2
+#define DIAGNOSTICS_RUN_MODE_PERIODIC  3
+
 static inline uint64_t ppc64_phys_to_real(uint64_t addr)
 {
     return addr & ~0xF000000000000000ULL;