On Mon, May 13, 2024 at 02:52:14PM +0800, 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?
I don't know enough about KVM PMU to give feedback on the specific
choices, but in terms of how to do QAPI design, this looks like a
good start.
With regards,
Daniel
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