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

[Shaoqin Huang <shahuang@redhat.com>]

Hi Zhao,

Thanks for your proposed idea. If you are willing to take the PMU Filter 
Enabling work, you can do it. I won't update this series anymore due to 
the QAPI restriction. I really appreciate if you can implement that.

Thanks,
Shaoqin

On 5/13/24 14:52, Zhao Liu wrote:
> 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
> 

-- 
Shaoqin