Re: [PATCH v9] arm/kvm: Enable support for KVM_ARM_VCPU_PMU_V3_FILTER

[Zhao Liu <zhao1.liu@xxxxxxxxx>]

Hi Daniel,

> Please describe it in terms of a QAPI definition, as that's what we're
> striving for with all QEMU public interfaces. Once the QAPI design is
> agreed, then the -object mapping is trivial, as -object's JSON format
> supports arbitrary QAPI structures.

Thank you for your guidance!

I rethought and and modified my previous proposal:

Let me show the command examples firstly:
  * Add a single event:
    (x86) -object kvm-pmu-event,id=e0,action=allow,format=x86-default,\
                  select=0x3c,umask=0x00
    (arm or general) -object kvm-pmu-event,id=e1,action=deny,\
                             format=raw,code=0x01
 
  * Add a counter bitmap:
    (x86) -object kvm-pmu-counter,id=cnt,action=allow,type=x86-fixed,\
                  bitmap=0xffff0000
 
  * Add an event list (must use Json syntax format):
   (x86) -object '{"qom-type":"kvm-pmu-event-list","id"="filter0","action"="allow","format"="x86-default","events=[{"select"=0x3c,"umask"=0x00},{"select"=0x2e,"umask"=0x4f}]'
   (arm) -object '{"qom-type":"kvm-pmu-event-list","id"="filter1","action"="allow","format"="raw","events"=[{"code"=0x01},{"code"=0x02}]'


The specific JSON definitions are as follows (IIUC, this is "in terms of
a QAPI definition", right? ;-)): 
* Define PMU event and counter bitmap with JSON format:
  - basic filter action:

  { 'enum': 'KVMPMUFilterAction',
    'prefix': 'KVM_PMU_FILTER_ACTION',
    'data': ['deny', 'allow' ] }

  - PMU counter:

  { 'enum': 'KVMPMUCounterType',
    'prefix': 'KVM_PMU_COUNTER_TYPE',
    'data': [ 'x86-fixed' ] }

  { 'struct': 'KVMPMUX86FixedCounter',
    'data': { 'bitmap': 'uint32' } }

  - PMU events (total 3 formats):

  # 3 encoding formats: "raw" is compatible with shaoqin's ARM format as
  # well as the x86 raw format, and could support other architectures in
  # the future.
  { 'enum': 'KVMPMUEventEncodeFmt',
    'prefix': 'KVM_PMU_EVENT_ENCODE_FMT',
    'data': ['raw', 'x86-default', 'x86-masked-entry' ] }

  # A general format.
  { 'struct': 'KVMPMURawEvent',
    'data': { 'code': 'uint64' } }

  # x86-specific
  { 'struct': 'KVMPMUX86DefalutEvent',
    'data': { 'select': 'uint16',
              'umask': 'uint16' } }

  # another x86 specific
  { 'struct': 'KVMPMUX86MaskedEntry',
    'data': { 'select': 'uint16',
              'match': 'uint8',
              'mask': 'uint8',
              'exclude': 'bool' } }

  # And their list wrappers:
  { 'struct': 'KVMPMURawEventList',
    'data': { 'events': ['KVMPMURawEvent'] } }

  { 'struct': 'KVMPMUX86DefalutEventList',
    'data': { 'events': ['KVMPMUX86DefalutEvent'] } }

  { 'struct': 'KVMPMUX86MaskedEntryList',
    'data': { 'events': ['KVMPMUX86MaskedEntryList'] } }


Based on the above basic structs, we could provide 3 new more qom-types:
  - 'kvm-pmu-counter': 'KVMPMUFilterCounter'

  # This is a single object option to configure PMU counter
  # bitmap filter.
  { 'union': 'KVMPMUFilterCounter',
    'base': { 'action': 'KVMPMUFilterAction',
              'type': 'KVMPMUCounterType' },
    'discriminator': 'type',
    'data': { 'x86-fixed': 'KVMPMUX86FixedCounter' } }


  - 'kvm-pmu-counter': 'KVMPMUFilterCounter'

  # This option is used to configure a single PMU event for
  # PMU filter.
  { 'union': 'KVMPMUFilterEvent',
    'base': { 'action': 'KVMPMUFilterAction',
              'format': 'KVMPMUEventEncodeFmt' },
    'discriminator': 'format',
    'data': { 'raw': 'KVMPMURawEvent',
              'x86-default': 'KVMPMUX86DefalutEvent',
              'x86-masked-entry': 'KVMPMUX86MaskedEntry' } }


  - 'kvm-pmu-event-list': 'KVMPMUFilterEventList'

  # Used to configure multiple events.
  { 'union': 'KVMPMUFilterEventList',
    'base': { 'action': 'KVMPMUFilterAction',
              'format': 'KVMPMUEventEncodeFmt' },
    'discriminator': 'format',
    'data': { 'raw': 'KVMPMURawEventList',
              'x86-default': 'KVMPMUX86DefalutEventList',
              'x86-masked-entry': 'KVMPMUX86MaskedEntryList' } }


Compared to Shaoqin's original format, kvm-pmu-event-list is not able to
enumerate events continuously (similar to 0x00-0x30 before), and now
user must enumerate events one by one individually.

What do you think about the above 3 new commands?

Thanks and Best Regards,
Zhao