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

[Shaoqin Huang <shahuang@redhat.com>]

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?

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

Thanks,
Shaoqin

> 
> Yes, you would define a type in the qapi dir similar to how is
> done for IOThreadVirtQueueMapping, and then you can use that
> in the property setter method.
> 
> 
> With regards,
> Daniel

-- 
Shaoqin