target-ppc: force update of msr bits in cpu_post_load

Since env->msr has already been restored by the time cpu_post_load is called,
make sure that ppc_store_msr() is explicitly called with all msr bits except
MSR_TGPR marked as invalid.

This solves the issue where MSR flags aren't set correctly when restoring a VM
snapshot, in particular the internal env->excp_prefix value when MSR_EP has
been altered by a guest.
Signed-off-by: NMark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: NAlexander Graf <agraf@suse.de>

target-ppc/machine.c

@@ -159,6 +159,7 @@ static int cpu_post_load(void *opaque, int version_id)
     PowerPCCPU *cpu = opaque;
     CPUPPCState *env = &cpu->env;
     int i;
+    target_ulong msr;
 
     /*
      * We always ignore the source PVR. The user or management
@@ -190,7 +191,12 @@ static int cpu_post_load(void *opaque, int version_id)
         /* Restore htab_base and htab_mask variables */
         ppc_store_sdr1(env, env->spr[SPR_SDR1]);
     }
-    hreg_compute_hflags(env);
+
+    /* Mark msr bits except MSR_TGPR invalid before restoring */
+    msr = env->msr;
+    env->msr ^= ~(1ULL << MSR_TGPR);
+    ppc_store_msr(env, msr);
+
     hreg_compute_mem_idx(env);
 
     return 0;