Re: [PATCH v6 2/2] target/s390x: Store r1/r2 for page-translation exceptions during MVPG

[Thomas Huth <thuth@redhat.com>]

On 11/03/2021 20.44, David Hildenbrand wrote:
> The PoP states:
> 
>      When EDAT-1 does not apply, and a program interruption due to a
>      page-translation exception is recognized by the MOVE PAGE
>      instruction, the contents of the R1 field of the instruction are
>      stored in bit positions 0-3 of location 162, and the contents of
>      the R2 field are stored in bit positions 4-7.
> 
>      If [...] an ASCE-type, region-first-translation,
>      region-second-translation, region-third-translation, or
>      segment-translation exception was recognized, the contents of
>      location 162 are unpredictable.
> 
> So we have to write r1/r2 into the lowcore on page-translation
> exceptions. Simply handle all exceptions inside our mvpg helper now.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>   target/s390x/helper.h      |  2 +-
>   target/s390x/insn-data.def |  2 +-
>   target/s390x/mem_helper.c  | 46 +++++++++++++++++++++++---------------
>   target/s390x/translate.c   |  7 +++++-
>   4 files changed, 36 insertions(+), 21 deletions(-)
> 
> diff --git a/target/s390x/helper.h b/target/s390x/helper.h
> index 55bd1551e6..d4e4f3388f 100644
> --- a/target/s390x/helper.h
> +++ b/target/s390x/helper.h
> @@ -18,7 +18,7 @@ DEF_HELPER_3(srstu, void, env, i32, i32)
>   DEF_HELPER_4(clst, i64, env, i64, i64, i64)
>   DEF_HELPER_FLAGS_4(mvn, TCG_CALL_NO_WG, void, env, i32, i64, i64)
>   DEF_HELPER_FLAGS_4(mvo, TCG_CALL_NO_WG, void, env, i32, i64, i64)
> -DEF_HELPER_FLAGS_4(mvpg, TCG_CALL_NO_WG, i32, env, i64, i64, i64)
> +DEF_HELPER_FLAGS_4(mvpg, TCG_CALL_NO_WG, i32, env, i64, i32, i32)
>   DEF_HELPER_FLAGS_4(mvz, TCG_CALL_NO_WG, void, env, i32, i64, i64)
>   DEF_HELPER_3(mvst, i32, env, i32, i32)
>   DEF_HELPER_4(ex, void, env, i32, i64, i64)
> diff --git a/target/s390x/insn-data.def b/target/s390x/insn-data.def
> index e5b6efabf3..0bb1886a2e 100644
> --- a/target/s390x/insn-data.def
> +++ b/target/s390x/insn-data.def
> @@ -641,7 +641,7 @@
>   /* MOVE NUMERICS */
>       C(0xd100, MVN,     SS_a,  Z,   la1, a2, 0, 0, mvn, 0)
>   /* MOVE PAGE */
> -    C(0xb254, MVPG,    RRE,   Z,   r1_o, r2_o, 0, 0, mvpg, 0)
> +    C(0xb254, MVPG,    RRE,   Z,   0, 0, 0, 0, mvpg, 0)
>   /* MOVE STRING */
>       C(0xb255, MVST,    RRE,   Z,   0, 0, 0, 0, mvst, 0)
>   /* MOVE WITH OPTIONAL SPECIFICATION */
> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
> index 6f6e2f80f4..12e84a4285 100644
> --- a/target/s390x/mem_helper.c
> +++ b/target/s390x/mem_helper.c
> @@ -915,8 +915,10 @@ uint64_t HELPER(clst)(CPUS390XState *env, uint64_t c, uint64_t s1, uint64_t s2)
>   }
>   
>   /* move page */
> -uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
> +uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint32_t r1, uint32_t r2)
>   {
> +    const uint64_t src = get_address(env, r2) & TARGET_PAGE_MASK;
> +    const uint64_t dst = get_address(env, r1) & TARGET_PAGE_MASK;
>       const int mmu_idx = cpu_mmu_index(env, false);
>       const bool f = extract64(r0, 11, 1);
>       const bool s = extract64(r0, 10, 1);
> @@ -929,34 +931,42 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
>           tcg_s390_program_interrupt(env, PGM_SPECIFICATION, GETPC());
>       }
>   
> -    r1 = wrap_address(env, r1 & TARGET_PAGE_MASK);
> -    r2 = wrap_address(env, r2 & TARGET_PAGE_MASK);
> -
>       /*
> -     * TODO:
> -     * - Access key handling
> -     * - Store r1/r2 register identifiers at real location 162
> +     * We always manually handle exceptions such that we can properly store
> +     * r1/r2 to the lowcore on page-translation exceptions.
> +     *
> +     * TODO: Access key handling
>        */
> -    exc = access_prepare_nf(&srca, env, cco, r2, TARGET_PAGE_SIZE,
> +    exc = access_prepare_nf(&srca, env, true, src, TARGET_PAGE_SIZE,
>                               MMU_DATA_LOAD, mmu_idx, ra);
>       if (exc) {
> -        return 2;
> +        if (cco) {
> +            return 2;
> +        }
> +        goto inject_exc;
>       }
> -    exc = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
> +    exc = access_prepare_nf(&desta, env, true, dst, TARGET_PAGE_SIZE,
>                               MMU_DATA_STORE, mmu_idx, ra);
>       if (exc) {
> -#if !defined(CONFIG_USER_ONLY)
> -        if (exc == PGM_PROTECTION) {
> -            stq_phys(env_cpu(env)->as,
> -                     env->psa + offsetof(LowCore, trans_exc_code),
> -                     env->tlb_fill_tec);
> -            tcg_s390_program_interrupt(env, PGM_PROTECTION, ra);
> +        if (cco && exc != PGM_PROTECTION) {
> +            return 1;
>           }
> -#endif
> -        return 1;
> +        goto inject_exc;
>       }
>       access_memmove(env, &desta, &srca, ra);
>       return 0; /* data moved */
> +inject_exc:
> +#if !defined(CONFIG_USER_ONLY)
> +    if (exc != PGM_ADDRESSING) {
> +        stq_phys(env_cpu(env)->as, env->psa + offsetof(LowCore, trans_exc_code),
> +                 env->tlb_fill_tec);
> +    }
> +    if (exc == PGM_PAGE_TRANS) {
> +        stb_phys(env_cpu(env)->as, env->psa + offsetof(LowCore, op_access_id),
> +                 r1 << 4 | r2);
> +    }
> +#endif
> +    tcg_s390_program_interrupt(env, exc, ra);
>   }
>   
>   /* string copy */
> diff --git a/target/s390x/translate.c b/target/s390x/translate.c
> index 61dd0341e4..4f953ddfba 100644
> --- a/target/s390x/translate.c
> +++ b/target/s390x/translate.c
> @@ -3513,7 +3513,12 @@ static DisasJumpType op_mvo(DisasContext *s, DisasOps *o)
>   
>   static DisasJumpType op_mvpg(DisasContext *s, DisasOps *o)
>   {
> -    gen_helper_mvpg(cc_op, cpu_env, regs[0], o->in1, o->in2);
> +    TCGv_i32 t1 = tcg_const_i32(get_field(s, r1));
> +    TCGv_i32 t2 = tcg_const_i32(get_field(s, r2));
> +
> +    gen_helper_mvpg(cc_op, cpu_env, regs[0], t1, t2);
> +    tcg_temp_free_i32(t1);
> +    tcg_temp_free_i32(t2);
>       set_cc_static(s);
>       return DISAS_NEXT;
>   }
> 

Looks fine to me.

Reviewed-by: Thomas Huth <thuth@redhat.com>