Re: [virtio-comment] Re: [PATCH 0/2] Selective queue enabling

[Eugenio Perez Martin <eperezma@redhat.com>]

On Tue, Jun 13, 2023 at 9:53âAM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Tue, Jun 13, 2023 at 03:46:35AM -0400, Michael S. Tsirkin wrote:
> > On Mon, Jun 12, 2023 at 09:56:57AM +0200, Eugenio Perez Martin wrote:
> > > > > Another drawback of that is the long time a device can spend to
> > > > > reconfigure its memory maps.
> > > >
> > > > The map is already used for cvq though, I don't see why it would take
> > > > much more with this.
> > > >
> > >
> > > In the case of vDPA HW, CVQ maps may not need to reach the device's or
> > > platform IOMMU, so the modification of that mapping is way cheaper.
> >
> > Oh, I get it. It's setup time, but you are right.
> >
> > > > > taking that into account, does it make
> > > > > sense to send a new version with the bit 1 on enable?
> > > > >
> > > > > Thanks!
> > > >
> > > > Current hardware won't support the extra bit though.
>
>
> Thinking more about this, I think the following works:
>
> - enable all queues before DRIVER_OK
> - reset all data queues before DRIVER_OK
> - DRIVER_OK
> - CVQ commands
> - re-enable data queues
>
>
> No?
>

If it is valid to write to queue_reset before DRIVER_OK, then sure. I
asked for that in the past at
https://lists.oasis-open.org/archives/virtio-dev/202305/msg00329.html
.

>
>
> > --
> > MST
>
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