[RFC PATCH 2/3] target/arm: Handle SME-without-SVE on change of EL

Peter Maydell posted 3 patches 1 week, 6 days ago
Maintainers: Peter Maydell <peter.maydell@linaro.org>
There is a newer version of this series
[RFC PATCH 2/3] target/arm: Handle SME-without-SVE on change of EL
Posted by Peter Maydell 1 week, 6 days ago
aarch64_sve_change_el() currently assumes that SME implies
SVE, and will return without doing anything if SVE is not
implemented, skipping a possible requirement to change
the vector register state because the SME vector length
has changed. Update it to handle SME also.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/helper.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index a3dd84a2d6..bf3aca18b1 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -10128,8 +10128,8 @@ void aarch64_sve_change_el(CPUARMState *env, int old_el,
     int old_len, new_len;
     bool old_a64, new_a64, sm;
 
-    /* Nothing to do if no SVE.  */
-    if (!cpu_isar_feature(aa64_sve, cpu)) {
+    /* Nothing to do if no SVE or SME.  */
+    if (!cpu_isar_feature(aa64_sve, cpu) && !cpu_isar_feature(aa64_sme, cpu)) {
         return;
     }
 
-- 
2.43.0
Re: [RFC PATCH 2/3] target/arm: Handle SME-without-SVE on change of EL
Posted by Richard Henderson 1 week, 4 days ago
On 1/28/26 02:48, Peter Maydell wrote:
> aarch64_sve_change_el() currently assumes that SME implies
> SVE, and will return without doing anything if SVE is not
> implemented, skipping a possible requirement to change
> the vector register state because the SME vector length
> has changed. Update it to handle SME also.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   target/arm/helper.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index a3dd84a2d6..bf3aca18b1 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -10128,8 +10128,8 @@ void aarch64_sve_change_el(CPUARMState *env, int old_el,
>       int old_len, new_len;
>       bool old_a64, new_a64, sm;
>   
> -    /* Nothing to do if no SVE.  */
> -    if (!cpu_isar_feature(aa64_sve, cpu)) {
> +    /* Nothing to do if no SVE or SME.  */
> +    if (!cpu_isar_feature(aa64_sve, cpu) && !cpu_isar_feature(aa64_sme, cpu)) {
>           return;
>       }
>   

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~