[PATCH v4 05/17] target/ppc: Retain hflags_nmsr only for migration

[Richard Henderson <richard.henderson@linaro.org>]

We have eliminated all normal uses of hflags_nmsr.  We need
not even compute it except when we want to migrate.  Rename
the field to emphasize this.

Remove the fixme comment for migrating access_type.  This value
is only ever used with the current executing instruction, and
is never live when the cpu is halted for migration.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/ppc/cpu.h         | 4 ++--
 target/ppc/helper_regs.c | 2 --
 target/ppc/machine.c     | 9 ++++++---
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index 061d2eed1b..79c4033a42 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -1105,8 +1105,8 @@ struct CPUPPCState {
 #endif
 
     /* These resources are used only in QEMU core */
-    target_ulong hflags;      /* hflags is MSR & HFLAGS_MASK */
-    target_ulong hflags_nmsr; /* specific hflags, not coming from MSR */
+    target_ulong hflags;
+    target_ulong hflags_compat_nmsr; /* for migration compatibility */
     int immu_idx;     /* precomputed MMU index to speed up insn accesses */
     int dmmu_idx;     /* precomputed MMU index to speed up data accesses */
 
diff --git a/target/ppc/helper_regs.c b/target/ppc/helper_regs.c
index 95b9aca61f..a87e354ca2 100644
--- a/target/ppc/helper_regs.c
+++ b/target/ppc/helper_regs.c
@@ -104,8 +104,6 @@ void hreg_compute_hflags(CPUPPCState *env)
          */
         uint32_t le = extract32(env->spr[SPR_HID0], 3, 1);
         env->hflags |= le << MSR_LE;
-        /* Retain for backward compatibility with migration. */
-        env->hflags_nmsr = le << MSR_LE;
     }
 }
 
diff --git a/target/ppc/machine.c b/target/ppc/machine.c
index f6eeda9642..1f7a353c78 100644
--- a/target/ppc/machine.c
+++ b/target/ppc/machine.c
@@ -310,6 +310,10 @@ static int cpu_pre_save(void *opaque)
         }
     }
 
+    /* Retain migration compatibility for pre 6.0 for 601 machines. */
+    env->hflags_compat_nmsr = (env->flags & POWERPC_FLAG_HID0_LE
+                               ? env->hflags & MSR_LE : 0);
+
     return 0;
 }
 
@@ -829,9 +833,8 @@ const VMStateDescription vmstate_ppc_cpu = {
         /* Supervisor mode architected state */
         VMSTATE_UINTTL(env.msr, PowerPCCPU),
 
-        /* Internal state */
-        VMSTATE_UINTTL(env.hflags_nmsr, PowerPCCPU),
-        /* FIXME: access_type? */
+        /* Backward compatible internal state */
+        VMSTATE_UINTTL(env.hflags_compat_nmsr, PowerPCCPU),
 
         /* Sanity checking */
         VMSTATE_UINTTL_TEST(mig_msr_mask, PowerPCCPU, cpu_pre_2_8_migration),
-- 
2.25.1