Re: [PATCH v3 37/51] target/arm: Reset streaming sve state on exception boundaries

[Peter Maydell]

On Mon, 20 Jun 2022 at 19:14, Richard Henderson
 wrote:
>
> We can handle both exception entry and exception return by
> hooking into aarch64_sve_change_el.
>
> Signed-off-by: Richard Henderson 
> ---
>  target/arm/helper.c | 15 +--
>  1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index 26f4a4bc26..9c5b1a10eb 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -11754,6 +11754,19 @@ void aarch64_sve_change_el(CPUARMState *env, int 
> old_el,
>  return;
>  }
>
> +old_a64 = old_el ? arm_el_is_aa64(env, old_el) : el0_a64;
> +new_a64 = new_el ? arm_el_is_aa64(env, new_el) : el0_a64;
> +
> +/*
> + * Both AArch64.TakeException and AArch64.ExceptionReturn
> + * invoke ResetSVEState when taking an exception from, or
> + * returning to, AArch32 state when PSTATE.SM is enabled.
> + */
> +if (old_a64 != new_a64 && FIELD_EX64(env->svcr, SVCR, SM)) {
> +arm_reset_sve_state(env);
> +return;
> +}

Reviewed-by: Peter Maydell 

thanks
-- PMM

[PATCH v3 37/51] target/arm: Reset streaming sve state on exception boundaries

[Richard Henderson]

We can handle both exception entry and exception return by
hooking into aarch64_sve_change_el.

Signed-off-by: Richard Henderson 
---
 target/arm/helper.c | 15 +--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 26f4a4bc26..9c5b1a10eb 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -11754,6 +11754,19 @@ void aarch64_sve_change_el(CPUARMState *env, int 
old_el,
 return;
 }
 
+old_a64 = old_el ? arm_el_is_aa64(env, old_el) : el0_a64;
+new_a64 = new_el ? arm_el_is_aa64(env, new_el) : el0_a64;
+
+/*
+ * Both AArch64.TakeException and AArch64.ExceptionReturn
+ * invoke ResetSVEState when taking an exception from, or
+ * returning to, AArch32 state when PSTATE.SM is enabled.
+ */
+if (old_a64 != new_a64 && FIELD_EX64(env->svcr, SVCR, SM)) {
+arm_reset_sve_state(env);
+return;
+}
+
 /*
  * DDI0584A.d sec 3.2: "If SVE instructions are disabled or trapped
  * at ELx, or not available because the EL is in AArch32 state, then
@@ -11766,10 +11779,8 @@ void aarch64_sve_change_el(CPUARMState *env, int 
old_el,
  * we already have the correct register contents when encountering the
  * vq0->vq0 transition between EL0->EL1.
  */
-old_a64 = old_el ? arm_el_is_aa64(env, old_el) : el0_a64;
 old_len = (old_a64 && !sve_exception_el(env, old_el)
? sve_vqm1_for_el(env, old_el) : 0);
-new_a64 = new_el ? arm_el_is_aa64(env, new_el) : el0_a64;
 new_len = (new_a64 && !sve_exception_el(env, new_el)
? sve_vqm1_for_el(env, new_el) : 0);
 
-- 
2.34.1