RE: [virtio-comment] RE: [PATCH v3 2/2] content: Support enabling virtqueue after DRIVER_OK stage

[Cornelia Huck <cohuck@redhat.com>]

On Wed, Oct 25 2023, Parav Pandit <parav@nvidia.com> wrote:

> Hi Cornelia,
>
>> From: Parav Pandit <parav@nvidia.com>
>> Sent: Monday, October 23, 2023 8:52 PM
>> To: Cornelia Huck <cohuck@redhat.com>; Michael S. Tsirkin
>> <mst@redhat.com>
>> Cc: virtio-comment@lists.oasis-open.org; hengqi@linux.alibaba.com;
>> xuanzhuo@linux.alibaba.com; Shahaf Shuler <shahafs@nvidia.com>
>> Subject: RE: [virtio-comment] RE: [PATCH v3 2/2] content: Support enabling
>> virtqueue after DRIVER_OK stage
>> 
>> 
>> > From: virtio-comment@lists.oasis-open.org <virtio-comment@lists.oasis-
>> > open.org> On Behalf Of Cornelia Huck
>> > Sent: Monday, October 23, 2023 8:31 PM
>> >
>> > On Mon, Oct 23 2023, Parav Pandit <parav@nvidia.com> wrote:
>> >
>> > >> From: Cornelia Huck <cohuck@redhat.com>
>> > >> Sent: Monday, October 23, 2023 7:58 PM
>> > >
>> > >> On Mon, Oct 23 2023, Parav Pandit <parav@nvidia.com> wrote:
>> > >>
>> > >> >> From: virtio-comment@lists.oasis-open.org
>> > >> >> <virtio-comment@lists.oasis- open.org> On Behalf Of Cornelia
>> > >> >> Huck
>> > >> >> Sent: Monday, October 23, 2023 7:27 PM
>> > >> >
>> > >> >> Well, there are  still comments from me here that post-date v4
>> > >> >> (please wait for a bit before posting another version!), so I'll
>> > >> >> continue waiting for them to be addressed first.
>> > >> > The last one was [1].
>> > >> > Which I replied few days ago at [2].
>> > >> >
>> > >> > [1]
>> > >> > https://lists.oasis-open.org/archives/virtio-comment/202310/msg00
>> > >> > 24
>> > >> > 0.h
>> > >> > tml [2]
>> > >> > https://lists.oasis-open.org/archives/virtio-comment/202310/msg00
>> > >> > 24
>> > >> > 2.h
>> > >> > tml
>> > >>
>> > >> I still have some open questions from <87sf68cjn0.fsf@redhat.com>
>> > >> (first and last paragraph.)
>> > >
>> > > Above link is not accessible to me. ☹
>> >
>> > That's not a link, but a message id... many mail clients support
>> > searching by it, and you can also get it from lore:
>> >
>> > https://lore.kernel.org/all/87sf68cjn0.fsf@redhat.com/
>> >
>> > > I addressed your comments/questions in v4.
>> > > Can you please check v4 if they are addressed? I rewrote as you
>> > > suggested in
>> > v3.
>> >
>> > This was for points you did not agree with. (Again, it might be
>> > helpful to wait with posting a new version until discussion has
>> > somewhat
>> > concluded.)
>> Sure, will wait next time.
>> 
>> Your comment was,
>> =====
>> This is not really clear to me just from this text, especially if you just wrote
>> above that enabling or re-enabling is something different... my understanding
>> would be:
>> 
>> - if neither dynamic vqs nor queue reset are supported or negotiated,
>>   the only way to enable a vq is before DRIVER_OK, during setup
>> - both of these features rely on the transport supporting enabling
>>   individual queues (either a queue that has not been enabled before, or
>>   a queue that has been reset)
>> - the transport is supposed to use the same mechanism for either
>> 
>> Did I get it right? If so, I think we should make it a bit more clear.
>> =====
>> 
>> Above is clarified in below wording without complicating the queue_reset here.
>> 
>> Does that look ok to you?
>> 
>> +When VIRTIO_F_RING_DYNAMIC is not negotiated, the driver enables the
>> +virtqueues during the device initialization sequence, i.e. after the
>> +device sets the FEATURES_OK status bit and before the driver setting the
>> DRIVER_OK status bit.
>> +
>> +When VIRTIO_F_RING_DYNAMIC is negotiated, the driver is not required to
>> +enable every virtqueue it wants to use before setting the DRIVER_OK
>> +status bit; the driver can choose to enable a virtqueue even after the
>> +driver has set the DRIVER_OK status bit. The virtqueue enable mechanism is
>> transport specific.
>> +
>
> Can you please respond?
> We must make progress with this and the flow filters which are depending on this for a long time now.

I will not be able to look at this before Friday.


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