Re: [Qemu-devel] [PATCH v2 18/28] s390x/tcg: MVC: Fault-safe handling on destructive overlaps

[Richard Henderson]

On 9/6/19 3:57 AM, David Hildenbrand wrote:
> +static S390Access access_prepare(CPUS390XState *env, vaddr vaddr, int size,
> +                                 MMUAccessType access_type, uintptr_t ra)
> +{
> +    int mmu_idx = cpu_mmu_index(env, false);
> +
> +    return access_prepare_idx(env, vaddr, size, access_type, mmu_idx, ra);
> +}
> +
>  static void access_memset_idx(CPUS390XState *env, vaddr vaddr, uint8_t byte,
>                                int size, int mmu_idx, uintptr_t ra)
>  {
> @@ -420,9 +428,13 @@ static uint32_t do_helper_mvc(CPUS390XState *env, 
> uint32_t l, uint64_t dest,
>      } else if (!is_destructive_overlap(env, dest, src, l)) {
>          access_memmove(env, dest, src, l, ra);
>      } else {
> +        S390Access srca = access_prepare(env, src, l, MMU_DATA_LOAD, ra);
> +        S390Access desta = access_prepare(env, dest, l, MMU_DATA_STORE, ra);

I was just thinking it might be better to drop the non-idx functions:
access_prepare, access_memset, access_memmove.  What this is leading to is
computation of cpu_mmu_index multiple times, as here.

It could just as easily be hoisted to the top of do_helper_mvc and used in all
of the sub-cases.

That said, the code here is correct so
Reviewed-by: Richard Henderson <address@hidden>

r~