Re: [PATCH v8] arm/kvm: Enable support for KVM_ARM_VCPU_PMU_V3_FILTER

[Kevin Wolf <kwolf@redhat.com>]

Am 29.03.2024 um 04:45 hat Shaoqin Huang geschrieben:
> Hi Daniel,
> 
> On 3/25/24 16:55, Daniel P. Berrangé wrote:
> > On Mon, Mar 25, 2024 at 01:35:58PM +0800, Shaoqin Huang wrote:
> > > Hi Daniel,
> > > 
> > > Thanks for your reviewing. I see your comments in the v7.
> > > 
> > > I have some doubts about what you said about the QAPI. Do you want me to
> > > convert the current design into the QAPI parsing like the
> > > IOThreadVirtQueueMapping? And we need to add new json definition in the
> > > qapi/ directory?
> 
> I have defined the QAPI for kvm-pmu-filter like below:
> 
> +##
> +# @FilterAction:
> +#
> +# The Filter Action
> +#
> +# @a: Allow
> +#
> +# @d: Disallow
> +#
> +# Since: 9.0
> +##
> +{ 'enum': 'FilterAction',
> +  'data': [ 'a', 'd' ] }
> +
> +##
> +# @SingleFilter:
> +#
> +# Lazy
> +#
> +# @action: the action
> +#
> +# @start: the start
> +#
> +# @end: the end
> +#
> +# Since: 9.0
> +##
> +
> +{ 'struct': 'SingleFilter',
> + 'data': { 'action': 'FilterAction', 'start': 'int', 'end': 'int' } }
> +
> +##
> +# @KVMPMUFilter:
> +#
> +# Lazy
> +#
> +# @filter: the filter
> +#
> +# Since: 9.0
> +##
> +
> +{ 'struct': 'KVMPMUFilter',
> +  'data': { 'filter': ['SingleFilter'] }}
> 
> And I guess I can use it by adding code like below:
> 
> --- a/hw/core/qdev-properties-system.c
> +++ b/hw/core/qdev-properties-system.c
> @@ -1206,3 +1206,35 @@ const PropertyInfo qdev_prop_iothread_vq_mapping_list
> = {
>      .set = set_iothread_vq_mapping_list,
>      .release = release_iothread_vq_mapping_list,
>  };
> +
> +/* --- kvm-pmu-filter ---*/
> +
> +static void get_kvm_pmu_filter(Object *obj, Visitor *v,
> +        const char *name, void *opaque, Error **errp)
> +{
> +    KVMPMUFilter **prop_ptr = object_field_prop_ptr(obj, opaque);
> +
> +    visit_type_KVMPMUFilter(v, name, prop_ptr, errp);
> +}
> +
> +static void set_kvm_pmu_filter(Object *obj, Visitor *v,
> +        const char *name, void *opaque, Error **errp)
> +{
> +    KVMPMUFilter **prop_ptr = object_field_prop_ptr(obj, opaque);
> +    KVMPMUFilter *list;
> +
> +    printf("running the %s\n", __func__);
> +    if (!visit_type_KVMPMUFilter(v, name, &list, errp)) {
> +        return;
> +    }
> +
> +    printf("The name is %s\n", name);
> +    *prop_ptr = list;
> +}
> +
> +const PropertyInfo qdev_prop_kvm_pmu_filter = {
> +    .name = "KVMPMUFilter",
> +    .description = "der der",
> +    .get = get_kvm_pmu_filter,
> +    .set = set_kvm_pmu_filter,
> +};
> 
> +#define DEFINE_PROP_KVM_PMU_FILTER(_name, _state, _field) \
> +    DEFINE_PROP(_name, _state, _field, qdev_prop_kvm_pmu_filter, \
> +                KVMPMUFilter *)
> 
> --- a/target/arm/cpu.c
> +++ b/target/arm/cpu.c
> @@ -2439,6 +2441,7 @@ static Property arm_cpu_properties[] = {
>                          mp_affinity, ARM64_AFFINITY_INVALID),
>      DEFINE_PROP_INT32("node-id", ARMCPU, node_id, CPU_UNSET_NUMA_NODE_ID),
>      DEFINE_PROP_INT32("core-count", ARMCPU, core_count, -1),
> +    DEFINE_PROP_KVM_PMU_FILTER("kvm-pmu-filter", ARMCPU, kvm_pmu_filter),
>      DEFINE_PROP_END_OF_LIST()
>  };
> 
> And I guess I can use the new json format input like below:
> 
> qemu-system-aarch64 \
> 	-cpu host, '{"filter": [{"action": "a", "start": 0x10, "end": "0x11"}]}'
> 
> But it doesn't work. It seems like because the -cpu option doesn't
> support json format parameter.
> 
> Maybe I'm wrong. So I want to double check with if the -cpu option
> support json format nowadays?

As far as I can see, -cpu doesn't support JSON yet. But even if it did,
your command line would be invalid because the 'host,' part isn't JSON.

> If the -cpu option doesn't support json format, how I can use the QAPI
> for kvm-pmu-filter property?

This would probably mean QAPIfying all CPUs first, which sounds like a
major effort.

Kevin