netdev - Re: [PATCH 2/3] virtio: Define bit numbers for device independent features

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Date:   Thu, 17 Feb 2022 14:06:39 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Eli Cohen <elic@...dia.com>
Cc:     "Hemminger, Stephen" <stephen@...workplumber.org>,
        netdev <netdev@...r.kernel.org>,
        Si-Wei Liu <si-wei.liu@...cle.com>,
        Jianbo Liu <jianbol@...dia.com>,
        Gautam Dawar <gdawar@...inx.com>
Subject: Re: [PATCH 2/3] virtio: Define bit numbers for device independent features

On Wed, Feb 16, 2022 at 3:16 PM Eli Cohen <elic@...dia.com> wrote:
>
> On Mon, Feb 14, 2022 at 02:06:54PM +0800, Jason Wang wrote:
> >
> > 在 2022/2/10 下午5:27, Eli Cohen 写道:
> > > On Thu, Feb 10, 2022 at 04:35:28PM +0800, Jason Wang wrote:
> > > > On Thu, Feb 10, 2022 at 4:31 PM Eli Cohen <elic@...dia.com> wrote:
> > > > > On Thu, Feb 10, 2022 at 03:54:57PM +0800, Jason Wang wrote:
> > > > > > On Mon, Feb 7, 2022 at 8:56 PM Eli Cohen <elic@...dia.com> wrote:
> > > > > > > Define bit fields for device independent feature bits. We need them in a
> > > > > > > follow up patch.
> > > > > > >
> > > > > > > Also, define macros for start and end of these feature bits.
> > > > > > >
> > > > > > > Reviewed-by: Jianbo Liu <jianbol@...dia.com>
> > > > > > > Signed-off-by: Eli Cohen <elic@...dia.com>
> > > > > > > ---
> > > > > > >   include/uapi/linux/virtio_config.h | 16 ++++++++--------
> > > > > > >   1 file changed, 8 insertions(+), 8 deletions(-)
> > > > > > >
> > > > > > > diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
> > > > > > > index 3bf6c8bf8477..6d92cc31a8d3 100644
> > > > > > > --- a/include/uapi/linux/virtio_config.h
> > > > > > > +++ b/include/uapi/linux/virtio_config.h
> > > > > > > @@ -45,14 +45,14 @@
> > > > > > >   /* We've given up on this device. */
> > > > > > >   #define VIRTIO_CONFIG_S_FAILED         0x80
> > > > > > >
> > > > > > > -/*
> > > > > > > - * Virtio feature bits VIRTIO_TRANSPORT_F_START through
> > > > > > > - * VIRTIO_TRANSPORT_F_END are reserved for the transport
> > > > > > > - * being used (e.g. virtio_ring, virtio_pci etc.), the
> > > > > > > - * rest are per-device feature bits.
> > > > > > > - */
> > > > > > > -#define VIRTIO_TRANSPORT_F_START       28
> > > > > > > -#define VIRTIO_TRANSPORT_F_END         38
> > > > > > > +/* Device independent features per virtio spec 1.1 range from 28 to 38 */
> > > > > > > +#define VIRTIO_DEV_INDEPENDENT_F_START 28
> > > > > > > +#define VIRTIO_DEV_INDEPENDENT_F_END   38
> > > > > > Haven't gone through patch 3 but I think it's probably better not
> > > > > > touch uapi stuff. Or we can define those macros in other place?
> > > > > >
> > > > > I can put it in vdpa.c
> > > > >
> > > > > > > +
> > > > > > > +#define VIRTIO_F_RING_INDIRECT_DESC 28
> > > > > > > +#define VIRTIO_F_RING_EVENT_IDX 29
> > > > > > > +#define VIRTIO_F_IN_ORDER 35
> > > > > > > +#define VIRTIO_F_NOTIFICATION_DATA 38
> > > > > > This part belongs to the virtio_ring.h any reason not pull that file
> > > > > > instead of squashing those into virtio_config.h?
> > > > > >
> > > > > Not sure what you mean here. I can't find virtio_ring.h in my tree.
> > > > I meant just copy the virtio_ring.h in the linux tree. It seems cleaner.
> > > I will still miss VIRTIO_F_ORDER_PLATFORM and VIRTIO_F_NOTIFICATION_DATA
> > > which are only defined in drivers/net/ethernet/sfc/mcdi_pcol.h for block
> > > devices only.
> > >
> > > What would you suggest to do with them? Maybe define them in vdpa.c?
> >
> >
> > I meant maybe we need a full synchronization from the current Linux uapi
> > headers for virtio_config.h and and add virtio_ring.h here.
> >
>
> virtio_config.h is updatd already and virtio_ring.h does not add any
> flag definition that we're missing.
>
> The flags I was missing are
> +#define VIRTIO_F_IN_ORDER 35
> +#define VIRTIO_F_NOTIFICATION_DATA 38

Right, so Gautam posted a path for _F_IN_ORDER [1].

We probably need another patch for NOTIFICATION_DATA.


>
> and both of these do not appear in the linux headers. They appear as
> block specific flags:
>
> drivers/net/ethernet/sfc/mcdi_pcol.h:21471:#define VIRTIO_BLK_CONFIG_VIRTIO_F_IN_ORDER_LBN 35
> drivers/net/ethernet/sfc/mcdi_pcol.h:21480:#define VIRTIO_BLK_CONFIG_VIRTIO_F_NOTIFICATION_DATA_LBN 38
>
> So I just defined these two in vdpa.c (in patch v1).

Fine, but we need to remove them if we get update from linux kernel uapi headers

[1] https://lkml.org/lkml/2022/2/15/43

Thanks

>
> > Thanks
> >
> >
> > >
> > > > Thanks
> > > >
> > > > > > Thanks
> > > > > >
> > > > > > >   #ifndef VIRTIO_CONFIG_NO_LEGACY
> > > > > > >   /* Do we get callbacks when the ring is completely used, even if we've
> > > > > > > --
> > > > > > > 2.34.1
> > > > > > >
> >
>