Re: [Qemu-devel] [PATCH 5/7] ppc: force update of all msr bits in cpu_post_load

[Paolo Bonzini]

On 23/12/2014 01:36, Mark Cave-Ayland wrote:
> 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 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: Mark Cave-Ayland <address@hidden>
> ---
>  target-ppc/machine.c |    8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/target-ppc/machine.c b/target-ppc/machine.c
> index c801b82..9669063 100644
> --- a/target-ppc/machine.c
> +++ b/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 all msr bits invalid before restoring */
> +    msr = env->msr;
> +    env->msr = ~env->msr;
> +    ppc_store_msr(env, msr);
> +
>      hreg_compute_mem_idx(env);
>  
>      return 0;
> 

This is wrong for this line of hreg_store_msr:

    if (unlikely((env->flags & POWERPC_FLAG_TGPR) &&
                 ((value ^ env->msr) & (1 << MSR_TGPR)))) {
        /* Swap temporary saved registers with GPRs */
        hreg_swap_gpr_tgpr(env);
    }

I think you need to change the ~ with "^ ~(1 << MSR_TGPR)".

Paolo