virtio — archive

[Parav Pandit <mgurtovoy@nvidia.com>]

> From: Max Gurtovoy <mgurtovoy@nvidia.com> > Sent: Wednesday, April 26, 2023 6:31 PM > >>> > >>>>> +If VIRTIO_F_ADMIN_VQ has been negotiated, and if the driver > >>>>> +configures any administration virtqueues, the driver MUST > >>>>> +configure the administration virtqueues using the index in the > >>>>> +range \field{admin_queue_index} to \field{admin_queue_index} + > >>>>> +\field{admin_queue_num} - 1 inclusive. > >>>>> +The driver MAY configure less administration virtqueues than > >>>>> +supported by the device. > >>>> > >>>> we need to say something about other virtq's indexes. > >>>> For example, if aq index = 0 then for the vblk device the request > >>>> queues would start from index = 1. > >>>> > >>>> can we address this ? > >>> > >>> It may slightly complicate the device implementation when device > >>> dynamically changes the VQ indices based on the negotiation of the > >>> feature bit. > >>> Also the drivers with and without need a different VQ index handling. > >>> > >>> I am thinking that aq index should not overlap with the vq index in > >>> range exposed by num_queues field. > >>> > >>> This also aligns to the exclusion of aq count from num_queues field. > >> > >> The namespace of the aq and other vq index is the same. > >> And the configuration is done using the same queue_select and other > registers. > >> Thus, we need to address the above comment otherwise all the device > >> virtqueues chapters are wrong. > > > > Michael has added below line in this patch in num_queues description so it > covers the exclusion part. > > > > + This excludes administration virtqueues if any are supported. > > > > This is not related to what I was talking about. > > For example if vnet device: > > 0 receiveq1 > 1 transmitq1 > ... > 2(N-1) receiveqN > 2(N-1)+1 transmitqN > 2N controlq > N=1 if neither VIRTIO_NET_F_MQ nor VIRTIO_NET_F_RSS are negotiated, > otherwise N is set by max_- virtqueue_pairs. > controlq only exists if VIRTIO_NET_F_CTRL_VQ set > > and in vfs device: > > 0 hiprio > 1...n request queues > > So if one device will expose adminq that will be with index 0 the above is wrong > description. > > Agree that this should be addressed ? Oh yes, I agree. In response [1] I acked it as, "I am thinking that aq index should not overlap with the vq index in range exposed by num_queues field." So, admin_queue_index description needs to have description like below. admin_queue_index must be greater than or equal to the value of num_queues. Yes? [1] a4b1596c-2132-714a-7557-fa5249a55945@nvidia.com/">https://lore.kernel.org/virtio-dev/a4b1596c-2132-714a-7557-fa5249a55945@nvidia.com/