Do not assume SME implies SVE.  Ensure that the
non-streaming check is present along the SME path,
since it is not implied by sme_*_enabled_check.

Cc: qemu-stable@nongnu.org
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/tcg/translate-a64.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index bb49a2ce90..d7b0c81773 100644
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -1387,11 +1387,8 @@ static bool fp_access_check_only(DisasContext *s)
     return true;
 }
 
-static bool fp_access_check(DisasContext *s)
+static bool nonstreaming_check(DisasContext *s)
 {
-    if (!fp_access_check_only(s)) {
-        return false;
-    }
     if (s->sme_trap_nonstreaming && s->is_nonstreaming) {
         gen_exception_insn(s, 0, EXCP_UDEF,
                            syn_smetrap(SME_ET_Streaming, false));
@@ -1400,6 +1397,11 @@ static bool fp_access_check(DisasContext *s)
     return true;
 }
 
+static bool fp_access_check(DisasContext *s)
+{
+    return fp_access_check_only(s) && nonstreaming_check(s);
+}
+
 /*
  * Return <0 for non-supported element sizes, with MO_16 controlled by
  * FEAT_FP16; return 0 for fp disabled; otherwise return >0 for success.
@@ -1450,11 +1452,20 @@ static int fp_access_check_vector_hsd(DisasContext *s, bool is_q, MemOp esz)
  */
 bool sve_access_check(DisasContext *s)
 {
-    if (s->pstate_sm || !dc_isar_feature(aa64_sve, s)) {
-        bool ret;
+    bool ret;
 
-        assert(dc_isar_feature(aa64_sme, s));
-        ret = sme_sm_enabled_check(s);
+    switch (dc_isar_feature(aa64_sme, s)) {
+    case true:
+        if (s->pstate_sm) {
+            ret = sme_enabled_check(s);
+        } else if (!dc_isar_feature(aa64_sve, s)) {
+            ret = sme_sm_enabled_check(s);
+        } else {
+            break;
+        }
+        if (ret) {
+            ret = nonstreaming_check(s);
+        }
         s->sve_access_checked = (ret ? 1 : -1);
         return ret;
     }
-- 
2.43.0

On Sun, 22 Jun 2025 at 22:36, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Do not assume SME implies SVE.  Ensure that the
> non-streaming check is present along the SME path,
> since it is not implied by sme_*_enabled_check.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/arm/tcg/translate-a64.c | 27 +++++++++++++++++++--------
>  1 file changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
> index bb49a2ce90..d7b0c81773 100644
> --- a/target/arm/tcg/translate-a64.c
> +++ b/target/arm/tcg/translate-a64.c
> @@ -1387,11 +1387,8 @@ static bool fp_access_check_only(DisasContext *s)
>      return true;
>  }
>
> -static bool fp_access_check(DisasContext *s)
> +static bool nonstreaming_check(DisasContext *s)
>  {
> -    if (!fp_access_check_only(s)) {
> -        return false;
> -    }
>      if (s->sme_trap_nonstreaming && s->is_nonstreaming) {
>          gen_exception_insn(s, 0, EXCP_UDEF,
>                             syn_smetrap(SME_ET_Streaming, false));
> @@ -1400,6 +1397,11 @@ static bool fp_access_check(DisasContext *s)
>      return true;
>  }
>
> +static bool fp_access_check(DisasContext *s)
> +{
> +    return fp_access_check_only(s) && nonstreaming_check(s);
> +}
> +
>  /*
>   * Return <0 for non-supported element sizes, with MO_16 controlled by
>   * FEAT_FP16; return 0 for fp disabled; otherwise return >0 for success.
> @@ -1450,11 +1452,20 @@ static int fp_access_check_vector_hsd(DisasContext *s, bool is_q, MemOp esz)
>   */
>  bool sve_access_check(DisasContext *s)
>  {
> -    if (s->pstate_sm || !dc_isar_feature(aa64_sve, s)) {
> -        bool ret;
> +    bool ret;
>
> -        assert(dc_isar_feature(aa64_sme, s));
> -        ret = sme_sm_enabled_check(s);
> +    switch (dc_isar_feature(aa64_sme, s)) {
> +    case true:

Why this rather than
       if (dc_isar_feature(aa64_sme, s)) {

?

> +        if (s->pstate_sm) {
> +            ret = sme_enabled_check(s);
> +        } else if (!dc_isar_feature(aa64_sve, s)) {
> +            ret = sme_sm_enabled_check(s);
> +        } else {
> +            break;
> +        }
> +        if (ret) {
> +            ret = nonstreaming_check(s);
> +        }
>          s->sve_access_checked = (ret ? 1 : -1);
>          return ret;
>      }

Otherwise
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM

On 6/24/25 06:58, Peter Maydell wrote:
>> +    switch (dc_isar_feature(aa64_sme, s)) {
>> +    case true:
> 
> Why this rather than
>         if (dc_isar_feature(aa64_sme, s)) {
> 
> ?
> 
>> +        if (s->pstate_sm) {
>> +            ret = sme_enabled_check(s);
>> +        } else if (!dc_isar_feature(aa64_sve, s)) {
>> +            ret = sme_sm_enabled_check(s);
>> +        } else {
>> +            break;
>> +        }

I used break instead of a goto, or replicating


>> +        if (ret) {
>> +            ret = nonstreaming_check(s);
>> +        }
>>           s->sve_access_checked = (ret ? 1 : -1);
>>           return ret;

this block.


r~