[Qemu-devel] [PATCH 4/5] ppc: Improve PCR bit selection in ppc_set_compat()

[Thomas Huth <thuth@redhat.com>]

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>
---
 target-ppc/translate_init.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
index fa09183..ee2bc14 100644
--- a/target-ppc/translate_init.c
+++ b/target-ppc/translate_init.c
@@ -9519,24 +9519,29 @@ 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) {
-- 
1.8.3.1