ppc: Improve PCR bit selection in ppc_set_compat()

When using an olderr PowerISA level, all the upper compatibility
bits have to be enabled, too. For example when we want to run
something in PowerISA 2.05 compatibility mode on POWER8, the bit
for 2.06 has to be set beside the bit for 2.05.
Additionally, to make sure that we do not set bits that are not
supported by the host, we apply a mask with the known-to-be-good
bits here, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
[dwg: Added some #ifs to fix compile on 32-bit targets]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

target-ppc/cpu.h

@@ -1187,7 +1187,9 @@ void ppc_store_msr (CPUPPCState *env, target_ulong value);
 
 void ppc_cpu_list (FILE *f, fprintf_function cpu_fprintf);
 int ppc_get_compat_smt_threads(PowerPCCPU *cpu);
+#if defined(TARGET_PPC64)
 void ppc_set_compat(PowerPCCPU *cpu, uint32_t cpu_version, Error **errp);
+#endif
 
 /* Time-base and decrementer management */
 #ifndef NO_CPU_IO_DEFS

target-ppc/translate_init.c

@@ -9515,28 +9515,34 @@ int ppc_get_compat_smt_threads(PowerPCCPU *cpu)
     return ret;
 }
 
+#ifdef TARGET_PPC64
 void ppc_set_compat(PowerPCCPU *cpu, uint32_t cpu_version, Error **errp)
 {
     int ret = 0;
     CPUPPCState *env = &cpu->env;
+    PowerPCCPUClass *host_pcc;
 
     cpu->cpu_version = cpu_version;
 
     switch (cpu_version) {
     case CPU_POWERPC_LOGICAL_2_05:
-        env->spr[SPR_PCR] = PCR_COMPAT_2_05;
+        env->spr[SPR_PCR] = PCR_TM_DIS | PCR_VSX_DIS | PCR_COMPAT_2_07 |
+                            PCR_COMPAT_2_06 | PCR_COMPAT_2_05;
         break;
     case CPU_POWERPC_LOGICAL_2_06:
-        env->spr[SPR_PCR] = PCR_COMPAT_2_06;
-        break;
     case CPU_POWERPC_LOGICAL_2_06_PLUS:
-        env->spr[SPR_PCR] = PCR_COMPAT_2_06;
+        env->spr[SPR_PCR] = PCR_TM_DIS | PCR_COMPAT_2_07 | PCR_COMPAT_2_06;
         break;
     default:
         env->spr[SPR_PCR] = 0;
         break;
     }
 
+    host_pcc = kvm_ppc_get_host_cpu_class();
+    if (host_pcc) {
+        env->spr[SPR_PCR] &= host_pcc->pcr_mask;
+    }
+
     if (kvm_enabled()) {
         ret = kvmppc_set_compat(cpu, cpu->cpu_version);
         if (ret < 0) {
@@ -9545,6 +9551,7 @@ void ppc_set_compat(PowerPCCPU *cpu, uint32_t cpu_version, Error **errp)
         }
     }
 }
+#endif
 
 static gint ppc_cpu_compare_class_pvr(gconstpointer a, gconstpointer b)
 {