On 7/19/25 8:57 AM, Markus Armbruster wrote:
> Paolo Abeni <pab...@redhat.com> writes:
>
>> Extend the VirtioDeviceFeatures struct with an additional u64
>> to track unknown features in the 64-127 bit range and decode
>> the full virtio features spaces for vhost and virtio devices.
>>
>> Also add entries for the soon-to-be-supported virtio net GSO over
>> UDP features.
>>
>> Signed-off-by: Paolo Abeni <pab...@redhat.com>
>
> [...]
>
>> diff --git a/hw/virtio/virtio-qmp.c b/hw/virtio/virtio-qmp.c
>> index 3b6377cf0d..03c6163cf4 100644
>> --- a/hw/virtio/virtio-qmp.c
>> +++ b/hw/virtio/virtio-qmp.c
>
> [...]
>
>> @@ -680,9 +715,10 @@ VirtioDeviceFeatures *qmp_decode_features(uint16_t
>> device_id, uint64_t bitmap)
>> g_assert_not_reached();
>> }
>>
>> - features->has_unknown_dev_features = bitmap != 0;
>> + features->has_unknown_dev_features = !virtio_features_empty(bitmap);
>> if (features->has_unknown_dev_features) {
>> - features->unknown_dev_features = bitmap;
>> + features->unknown_dev_features = bitmap[0];
>> + features->unknown_dev_features2 = bitmap[1];
>> }
>
> Why not assign unconditionally?
I stuck with the old/previous code style. I can move to unconditional
assignment in the next revision.
>> return features;
>
> [...]
>
>> diff --git a/qapi/virtio.json b/qapi/virtio.json
>> index 9d652fe4a8..f2e2dd6e97 100644
>> --- a/qapi/virtio.json
>> +++ b/qapi/virtio.json
>> @@ -490,14 +490,18 @@
>> # unique features)
>> #
>> # @unknown-dev-features: Virtio device features bitmap that have not
>> -# been decoded
>> +# been decoded (bits 0-63)
>> +#
>> +# @unknown-dev-features2: Virtio device features bitmap that have not
>> +# been decoded (bits 64-127)
>> #
>> # Since: 7.2
>> ##
>> { 'struct': 'VirtioDeviceFeatures',
>> 'data': { 'transports': [ 'str' ],
>> '*dev-features': [ 'str' ],
>> - '*unknown-dev-features': 'uint64' } }
>> + '*unknown-dev-features': 'uint64',
>> + '*unknown-dev-features2': 'uint64' } }
>>
>> ##
>> # @VirtQueueStatus:
>
> I wish we could simply widen @unknown-dev-features, but we don't have
> uint128, and adding it would risk breaking QMP clients. 64 bit integers
> are already troublesome in JSON.
>
> Does the example in x-query-virtio-status's doc comment need an update?
Yes, you are right, the output for the 'unknown features' field will
include leading zeros for the high 64 bits.
I will update it in the next revision, thanks!
Paolo
