Re: [PATCH 2/3] target/arm: Always add pmu property

[Akihiko Odaki]

On 2024/07/01 20:54, Peter Maydell wrote:
> On Sat, 29 Jun 2024 at 13:51, Akihiko Odaki <akihiko.odaki@daynix.com> wrote:
> > kvm-steal-time and sve properties are added for KVM even if the
> > corresponding features are not available. Always add pmu property too.
> >
> > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> > ---
> >   target/arm/cpu.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/target/arm/cpu.c b/target/arm/cpu.c
> > index 35fa281f1b98..0da72c12a5bd 100644
> > --- a/target/arm/cpu.c
> > +++ b/target/arm/cpu.c
> > @@ -1770,9 +1770,10 @@ void arm_cpu_post_init(Object *obj)
> >
> >       if (arm_feature(&cpu->env, ARM_FEATURE_PMU)) {
> >           cpu->has_pmu = true;
> > -        object_property_add_bool(obj, "pmu", arm_get_pmu, arm_set_pmu);
> >       }
> >
> > +    object_property_add_bool(obj, "pmu", arm_get_pmu, arm_set_pmu);
>
> This will allow the user to set the ARM_FEATURE_PMU feature
> bit on TCG CPUs where that doesn't make sense. If we want to
> make the property visible on all CPUs, we need to make it
> be an error to set it when it's not valid to set it (probably
> by adding some TCG/hvf equivalent to the "raise an error
> in arm_set_pmu()" code branch we already have for KVM).

Doesn't TCG support PMU though?
Certainly hvf needs some care on the other hand.

Regards,
Akihiko Odaki