Re: [PATCH v9 7/8] qmp: add QMP command x-query-virtio-queue-element

[Jonah Palmer <jonah.palmer@oracle.com>]

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On 11/10/21 08:52, Markus Armbruster wrote:
> Jonah Palmer<jonah.palmer@oracle.com>  writes:
>
>> From: Laurent Vivier<lvivier@redhat.com>
>>
>> This new command shows the information of a VirtQueue element.
>>
>> Signed-off-by: Jonah Palmer<jonah.palmer@oracle.com>
> [...]
>
>> diff --git a/qapi/virtio.json b/qapi/virtio.json
>> index 0f65044..c57fbc5 100644
>> --- a/qapi/virtio.json
>> +++ b/qapi/virtio.json
>> @@ -1061,3 +1061,180 @@
>>   { 'command': 'x-query-virtio-vhost-queue-status',
>>     'data': { 'path': 'str', 'queue': 'uint16' },
>>     'returns': 'VirtVhostQueueStatus', 'features': [ 'unstable' ] }
>> +
>> +##
>> +# @VirtioRingDescFlags:
>> +#
>> +# An enumeration of the virtio ring descriptor flags
>> +#
>> +# Since: 6.3
>> +#
>> +##
>> +
>> +{ 'enum': 'VirtioRingDescFlags',
>> +  'data': [ 'next', 'write', 'indirect', 'avail', 'used' ]
>> +}
>> +
>> +##
>> +# @VirtioRingDesc:
>> +#
>> +# Information regarding the VRing descriptor area
>> +#
>> +# @addr: guest physical address of the descriptor data
>> +#
>> +# @len: length of the descriptor data
>> +#
>> +# @flags: list of descriptor flags
>> +#
>> +# Since: 6.3
>> +#
>> +##
>> +
>> +{ 'struct': 'VirtioRingDesc',
>> +  'data': { 'addr': 'uint64',
>> +            'len': 'uint32',
>> +            'flags': [ 'VirtioRingDescFlags' ] } }
>> +
>> +##
>> +# @VirtioRingAvail:
>> +#
>> +# Information regarding the avail VRing (also known as the driver
>> +# area)
>> +#
>> +# @flags: VRingAvail flags
>> +#
>> +# @idx: VRingAvail index
>> +#
>> +# @ring: VRingAvail ring[] entry at provided index
>> +#
>> +# Since: 6.3
>> +#
>> +##
>> +
>> +{ 'struct': 'VirtioRingAvail',
>> +  'data': { 'flags': 'uint16',
>> +            'idx': 'uint16',
>> +            'ring': 'uint16' } }
>> +
>> +##
>> +# @VirtioRingUsed:
>> +#
>> +# Information regarding the used VRing (also known as the device
>> +# area)
>> +#
>> +# @flags: VRingUsed flags
>> +#
>> +# @idx: VRingUsed index
>> +#
>> +# Since: 6.3
>> +#
>> +##
>> +
>> +{ 'struct': 'VirtioRingUsed',
>> +  'data': { 'flags': 'uint16',
>> +            'idx': 'uint16' } }
>> +
>> +##
>> +# @VirtioQueueElement:
>> +#
>> +# Information regarding a VirtQueue VirtQueueElement including
>> +# descriptor, driver, and device areas
>> +#
>> +# @device-name: name of the VirtIODevice which this VirtQueue belongs
>> +#               to (for reference)
>> +#
>> +# @index: index of the element in the queue
>> +#
>> +# @ndescs: number of descriptors
>> +#
>> +# @descs: list of the descriptors
> Can @ndescs ever be not equal to the length of @descs?
>
> If no, it's redundant.

I don't believe so, no. Should I just remove @ndescs then?


Jonah

>> +#
>> +# @avail: VRingAvail info
>> +#
>> +# @used: VRingUsed info
>> +#
>> +# Since: 6.3
>> +#
>> +##
>> +
>> +{ 'struct': 'VirtioQueueElement',
>> +  'data': { 'device-name': 'str',
>> +            'index': 'uint32',
>> +            'ndescs': 'uint32',
>> +            'descs': [ 'VirtioRingDesc' ],
>> +            'avail': 'VirtioRingAvail',
>> +            'used': 'VirtioRingUsed' } }
>> +
>> +##
>> +# @x-query-virtio-queue-element:
>> +#
>> +# Return the information about a VirtQueue VirtQueueElement (by
>> +# default looks at the head of the queue)
>> +#
>> +# @path: VirtIODevice canonical QOM path
>> +#
>> +# @queue: VirtQueue index to examine
>> +#
>> +# @index: the index in the queue, by default head
>> +#
>> +# Features:
>> +# @unstable: This command is meant for debugging.
>> +#
>> +# Returns: VirtioQueueElement information
>> +#
>> +# Since: 6.3
>> +#
>> +# Examples:
>> +#
>> +# 1. Introspect on virtio-net virtqueue 0 at index 5
>> +#
>> +# -> { "execute": "x-query-virtio-queue-element",
>> +#      "arguments": { "path": "/machine/peripheral-anon/device[1]/virtio-backend",
>> +#                     "queue": 0,
>> +#                     "index": 5 }
>> +#    }
>> +# <- { "return": {
>> +#         "index": 5,
>> +#         "ndescs": 1,
>> +#         "device-name": "virtio-net",
>> +#         "descs": [ { "flags": ["write"], "len": 1536, "addr": 5257305600 } ],
>> +#         "avail": { "idx": 256, "flags": 0, "ring": 5 },
>> +#         "used": { "idx": 13, "flags": 0 } }
>> +#    }
>> +#
>> +# 2. Introspect on virtio-crypto virtqueue 1 at head
>> +#
>> +# -> { "execute": "x-query-virtio-queue-element",
>> +#      "arguments": { "path": "/machine/peripheral/crypto0/virtio-backend",
>> +#                     "queue": 1 }
>> +#    }
>> +# <- { "return": {
>> +#         "index": 0,
>> +#         "ndescs": 1,
>> +#         "device-name": "virtio-crypto",
>> +#         "descs": [ { "flags": [], "len": 0, "addr": 8080268923184214134 } ],
>> +#         "avail": { "idx": 280, "flags": 0, "ring": 0 },
>> +#         "used": { "idx": 280, "flags": 0 } }
>> +#    }
>> +#
>> +# 3. Introspect on virtio-scsi virtqueue 2 at head
>> +#
>> +# -> { "execute": "x-query-virtio-queue-element",
>> +#      "arguments": { "path": "/machine/peripheral-anon/device[2]/virtio-backend",
>> +#                     "queue": 2 }
>> +#    }
>> +# <- { "return": {
>> +#         "index": 19,
>> +#         "ndescs": 1,
>> +#         "device-name": "virtio-scsi",
>> +#         "descs": [ { "flags": ["used", "indirect", "write"], "len": 4099327944,
>> +#                      "addr": 12055409292258155293 } ],
>> +#         "avail": { "idx": 1147, "flags": 0, "ring": 19 },
>> +#         "used": { "idx": 1147, "flags": 0 } }
>> +#    }
>> +#
>> +##
>> +
>> +{ 'command': 'x-query-virtio-queue-element',
>> +  'data': { 'path': 'str', 'queue': 'uint16', '*index': 'uint16' },
>> +  'returns': 'VirtioQueueElement', 'features': [ 'unstable' ] }

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