Re: [Qemu-devel] [RFC v5 0/2] virtio: introduce `info virtio' hmp command

[Jan Dakinevich <jan.dakinevich@virtuozzo.com>]

I am going to reanimate works under this QMP/HMP. First of all, it
could be meaningful to settle what output would provide the QMP. I would
like to suggest the following description:

##
# @VirtioFeature:
##
{
    'struct': 'VirtioFeature',
    'data': {
        'name': 'str',
        'acked': 'bool'
    }
}

##
# @VirtioInfo:
##
{
    'struct': 'VirtioInfo',
    'data': {
        'qom-path': 'str',
        
        'status': 'uint8',
        'host-features': 'uint64',
        'guest-features': 'uint64',

        'status-names': ['str'],
        'common-features-names': ['VirtioFeature'],
        'device-features-names': ['VirtioFeature']
    }
}

##
# @query-virtio:
##
{
    'command': 'query-virtio',
    'data': {'*path': 'str'},
    'returns': ['VirtioInfo']
}

My final goal is to implement HMP which will print all exposed virtio
features (both common and device-specific) with their acknowledgements,
and virtio device configuration status. These are provided by last 3
fields in @VirtioInfo.

For these who are going make own decision on features and status
bitmask, respective fields with raw values are preserved.

So, I expect following data on the wire in response to `query-virtio'
command:

{
    "return": [
        {
            "qom-path": "/machine/peripheral-anon/device[0]/virtio-backend", "status": 15,
            "host-features": 6325010438,
            "guest-features": 5100273670,
            "status-names": [
                "acknowledge", 
                "driver", 
                "driver-ok", 
                "features-ok"
            ],
            "common-features-names": [
                {"name": "notify-on-empty", "acked": false},
                {"name": "any-layout", "acked": false},
                {"name": "indirect-desc", "acked": true},
                {"name": "event-idx", "acked": true},
                {"name": "bad-feature", "acked": false},
                {"name": "version-1", "acked": true}
            ],
            "device-features-names": [
                {"name": "hotplug", "acked": true},
                {"name": "change", "acked": true}
            ]
        }
    ]
}


Eric Blake, returning to your question which would probably appear again
after this mail:

>> +##
>> +# @query-virtio:
>> ...
>> +##
>> +{
>> +    'command': 'query-virtio',
>> +    'data': { '*path': 'str' },  
>
> Do we need filterable queries, or is it better to just have the
> command return info on all virtio devices at once and let the client
> filter the results as desired?

I think it would be better to do here. I suppose, the client which uses
HMP will not be happy on filtering monitor output.

-- 
Best regards
Jan Dakinevich