Re: [PATCH] target/arm: Restructure has_vfp_d32 test

[Cédric Le Goater]

On 6/19/23 16:02, Richard Henderson wrote:
> One cannot test for feature aa32_simd_r32 without first
> testing if AArch32 mode is supported at all.  This leads to
>
> qemu-system-aarch64: ARM CPUs must have both VFP-D32 and Neon or neither
>
> for Apple M1 cpus.

The orangepi5 board I use didn't have that kind problem.

> We already have a check for ARMv8-A never setting vfp-d32 true,
> so restructure the code so that AArch64 avoids the test entirely.
>
> Reported-by: Mads Ynddal <mads@ynddal.dk>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Cédric Le Goater <clg@kaod.org>


Thanks for the fix,

C.

> ---
>   target/arm/cpu.c | 28 +++++++++++++++-------------
>   1 file changed, 15 insertions(+), 13 deletions(-)
>
> diff --git a/target/arm/cpu.c b/target/arm/cpu.c
> index 353fc48567..706dbd37b1 100644
> --- a/target/arm/cpu.c
> +++ b/target/arm/cpu.c
> @@ -1402,25 +1402,27 @@ void arm_cpu_post_init(Object *obj)
>        * KVM does not currently allow us to lie to the guest about its
>        * ID/feature registers, so the guest always sees what the host has.
>        */
> -    if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)
> -        ? cpu_isar_feature(aa64_fp_simd, cpu)
> -        : cpu_isar_feature(aa32_vfp, cpu)) {
> -        cpu->has_vfp = true;
> -        if (!kvm_enabled()) {
> -            qdev_property_add_static(DEVICE(obj), &arm_cpu_has_vfp_property);
> +    if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
> +        if (cpu_isar_feature(aa64_fp_simd, cpu)) {
> +            cpu->has_vfp = true;
> +            cpu->has_vfp_d32 = true;
> +            if (tcg_enabled() || qtest_enabled()) {
> +                qdev_property_add_static(DEVICE(obj),
> +                                         &arm_cpu_has_vfp_property);
> +            }
>           }
> -    }
> -
> -    if (cpu->has_vfp && cpu_isar_feature(aa32_simd_r32, cpu)) {
> -        cpu->has_vfp_d32 = true;
> -        if (!kvm_enabled()) {
> +    } else if (cpu_isar_feature(aa32_vfp, cpu)) {
> +        cpu->has_vfp = true;
> +        if (cpu_isar_feature(aa32_simd_r32, cpu)) {
> +            cpu->has_vfp_d32 = true;
>               /*
>                * The permitted values of the SIMDReg bits [3:0] on
>                * Armv8-A are either 0b0000 and 0b0010. On such CPUs,
>                * make sure that has_vfp_d32 can not be set to false.
>                */
> -            if (!(arm_feature(&cpu->env, ARM_FEATURE_V8) &&
> -                  !arm_feature(&cpu->env, ARM_FEATURE_M))) {
> +            if ((tcg_enabled() || qtest_enabled())
> +                && !(arm_feature(&cpu->env, ARM_FEATURE_V8)
> +                     && !arm_feature(&cpu->env, ARM_FEATURE_M))) {
>                   qdev_property_add_static(DEVICE(obj),
>                                            &arm_cpu_has_vfp_d32_property);
>               }