Re: [Qemu-devel] [qemu-s390x] [PATCH v1 1/2] s390x/tcg: implement TEST PROTECTION

[Thomas Huth <thuth@redhat.com>]

On 18.12.2017 23:46, David Hildenbrand wrote:
> Linux uses TEST PROTECTION to sense for available memory locations.
> 
> Let's implement what we can for now (just as for the other instructions,
> excluding AR mode and special protection mechanisms).
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  target/s390x/helper.h     |  2 +-
>  target/s390x/mem_helper.c | 41 +++++++++++++++++++++++++++++++++++++++--
>  target/s390x/translate.c  |  2 +-
>  3 files changed, 41 insertions(+), 4 deletions(-)
> 
> diff --git a/target/s390x/helper.h b/target/s390x/helper.h
> index 2f17b62d3d..26c1b07b44 100644
> --- a/target/s390x/helper.h
> +++ b/target/s390x/helper.h
> @@ -137,7 +137,7 @@ DEF_HELPER_FLAGS_4(lctlg, TCG_CALL_NO_WG, void, env, i32, i64, i32)
>  DEF_HELPER_FLAGS_4(stctl, TCG_CALL_NO_WG, void, env, i32, i64, i32)
>  DEF_HELPER_FLAGS_4(stctg, TCG_CALL_NO_WG, void, env, i32, i64, i32)
>  DEF_HELPER_FLAGS_2(testblock, TCG_CALL_NO_WG, i32, env, i64)
> -DEF_HELPER_FLAGS_2(tprot, TCG_CALL_NO_RWG, i32, i64, i64)
> +DEF_HELPER_FLAGS_3(tprot, TCG_CALL_NO_RWG, i32, env, i64, i64)
>  DEF_HELPER_FLAGS_2(iske, TCG_CALL_NO_RWG_SE, i64, env, i64)
>  DEF_HELPER_FLAGS_3(sske, TCG_CALL_NO_RWG, void, env, i64, i64)
>  DEF_HELPER_FLAGS_2(rrbe, TCG_CALL_NO_RWG, i32, env, i64)
> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
> index 2625d843b3..359e446c6f 100644
> --- a/target/s390x/mem_helper.c
> +++ b/target/s390x/mem_helper.c
> @@ -1717,9 +1717,46 @@ uint32_t HELPER(testblock)(CPUS390XState *env, uint64_t real_addr)
>      return 0;
>  }
>  
> -uint32_t HELPER(tprot)(uint64_t a1, uint64_t a2)
> +uint32_t HELPER(tprot)(CPUS390XState *env, uint64_t a1, uint64_t a2)
>  {
> -    /* XXX implement */
> +    S390CPU *cpu = s390_env_get_cpu(env);
> +    CPUState *cs = CPU(cpu);
> +
> +    /*
> +     * TODO: we currently don't handle all access protection types
> +     * (including access-list and key-controlled) as well as AR mode.
> +     */

Maybe add some "if (a2 & 0xf0) qemu_log_mask(LOG_UNIMPL, ...)" so that
we've got a chance to detect such conditions later?

> +    if (!s390_cpu_virt_mem_check_write(cpu, a1, 0, 1)) {
> +        /* Fetching permitted; storing permitted */
> +        return 0;
> +    }
> +    switch (env->int_pgm_code) {
> +    case PGM_PROTECTION:
> +        /* Fetching permitted; storing not permitted */
> +        cs->exception_index = 0;
> +        return 1;
> +    case PGM_ADDRESSING:
> +        /* Fetching not permitted; storing not permitted */
> +        cs->exception_index = 0;
> +        return 2;
> +    case PGM_ASCE_TYPE:
> +    case PGM_REG_FIRST_TRANS:
> +    case PGM_REG_SEC_TRANS:
> +    case PGM_REG_THIRD_TRANS:
> +    case PGM_SEGMENT_TRANS:
> +    case PGM_PAGE_TRANS:
> +    case PGM_ALET_SPEC:
> +    case PGM_ALEN_SPEC:
> +    case PGM_ALE_SEQ:
> +    case PGM_ASTE_VALID:
> +    case PGM_ASTE_SEQ:
> +    case PGM_EXT_AUTH:
> +        /* Translation not available */
> +        cs->exception_index = 0;
> +        return 3;
> +    }
> +    /* any other exception is forwarded to the guest */
> +    s390_cpu_virt_mem_handle_exc(cpu, GETPC());
>      return 0;
>  }
>  
> diff --git a/target/s390x/translate.c b/target/s390x/translate.c
> index eede2ed157..fdcc2ffb3d 100644
> --- a/target/s390x/translate.c
> +++ b/target/s390x/translate.c
> @@ -4534,7 +4534,7 @@ static ExitStatus op_testblock(DisasContext *s, DisasOps *o)
>  
>  static ExitStatus op_tprot(DisasContext *s, DisasOps *o)
>  {
> -    gen_helper_tprot(cc_op, o->addr1, o->in2);
> +    gen_helper_tprot(cc_op, cpu_env, o->addr1, o->in2);
>      set_cc_static(s);
>      return NO_EXIT;
>  }
> 

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