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

[Richard Henderson <richard.henderson@linaro.org>]

On 6/20/23 07:29, Philippe Mathieu-Daudé wrote:
> On 19/6/23 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.
>>
>> 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>
>> ---
>>   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);
>>               }
> 
> Shouldn't we also change:
> 
> -- >8 --
> @@ -1431,7 +1431,7 @@ void arm_cpu_post_init(Object *obj)
> 
>       if (arm_feature(&cpu->env, ARM_FEATURE_NEON)) {
>           cpu->has_neon = true;
> -        if (!kvm_enabled()) {
> +        if (tcg_enabled() || qtest_enabled()) {
>               qdev_property_add_static(DEVICE(obj), &arm_cpu_has_neon_property);
>           }
>       }
> ---
> 
> ?

Yes, I missed that, being just out of view.  :-)

r~