[Qemu-ppc] [RFC 12/17] ppc: Migrate compatibility mode

[David Gibson]

Server-class POWER CPUs can be put into several compatibility modes.  These
can be specified on the command line, or negotiated by the guest during
boot.

Currently we don't migrate the compatibility mode, which means after a
migration the guest will revert to running with whatever compatibility
mode (or none) specified on the command line.

With the limited range of CPUs currently used, this doesn't usually cause
a problem, but it could.  Fix this by adding the compatibility mode (if
set) to the migration stream.

Signed-off-by: David Gibson <address@hidden>
---
 target-ppc/machine.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/target-ppc/machine.c b/target-ppc/machine.c
index 4820f22..5d87ff6 100644
--- a/target-ppc/machine.c
+++ b/target-ppc/machine.c
@@ -9,6 +9,7 @@
 #include "mmu-hash64.h"
 #include "migration/cpu.h"
 #include "exec/exec-all.h"
+#include "qapi/error.h"
 
 static int cpu_load_old(QEMUFile *f, void *opaque, int version_id)
 {
@@ -176,6 +177,20 @@ static int cpu_post_load(void *opaque, int version_id)
      * software has to take care of running QEMU in a compatible mode.
      */
     env->spr[SPR_PVR] = env->spr_cb[SPR_PVR].default_value;
+
+#if defined(TARGET_PPC64)
+    if (cpu->compat_pvr) {
+        Error *local_err = NULL;
+
+        ppc_set_compat(cpu, cpu->compat_pvr, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            error_free(local_err);
+            return -1;
+        }
+    }
+#endif
+
     env->lr = env->spr[SPR_LR];
     env->ctr = env->spr[SPR_CTR];
     cpu_write_xer(env, env->spr[SPR_XER]);
@@ -528,6 +543,24 @@ static const VMStateDescription vmstate_tlbmas = {
     }
 };
 
+static bool compat_needed(void *opaque)
+{
+    PowerPCCPU *cpu = opaque;
+
+    return cpu->compat_pvr != 0;
+}
+
+static const VMStateDescription vmstate_compat = {
+    .name = "cpu/compat",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = compat_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(compat_pvr, PowerPCCPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 const VMStateDescription vmstate_ppc_cpu = {
     .name = "cpu",
     .version_id = 5,
@@ -580,6 +613,7 @@ const VMStateDescription vmstate_ppc_cpu = {
         &vmstate_tlb6xx,
         &vmstate_tlbemb,
         &vmstate_tlbmas,
+        &vmstate_compat,
         NULL
     }
 };
-- 
2.7.4