On Mon, Jun 19, 2023 at 07:16:20AM -0400, Michael S. Tsirkin wrote:
> On Mon, Jun 19, 2023 at 06:57:38PM +0800, Heng Qi wrote:
> > Lay the foundation for the subsequent patch
>
> which subsequent patch? this is the last one in series.
>
> > to complete the coexistence
> > of XDP and virtio-net guest csum.
> >
> > Signed-off-by: Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>
> > Reviewed-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> > ---
> > drivers/net/virtio_net.c | 4 +---
> > 1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 25b486ab74db..79471de64b56 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -60,7 +60,6 @@ static const unsigned long guest_offloads[] = {
> > VIRTIO_NET_F_GUEST_TSO6,
> > VIRTIO_NET_F_GUEST_ECN,
> > VIRTIO_NET_F_GUEST_UFO,
> > - VIRTIO_NET_F_GUEST_CSUM,
> > VIRTIO_NET_F_GUEST_USO4,
> > VIRTIO_NET_F_GUEST_USO6,
> > VIRTIO_NET_F_GUEST_HDRLEN
>
> What is this doing? Drop support for VIRTIO_NET_F_GUEST_CSUM? Why?
guest_offloads[] is used by the VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET
command to switch features when XDP is loaded/unloaded.
If the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is negotiated:
1. When XDP is loaded, virtnet_xdp_set() uses virtnet_clear_guest_offloads()
to automatically turn off the features in guest_offloads[].
2. when XDP is unloaded, virtnet_xdp_set() uses virtnet_restore_guest_offloads()
to automatically restore the features in guest_offloads[].
Now, this work no longer makes XDP and _F_GUEST_CSUM mutually
exclusive, so this patch removed the _F_GUEST_CSUM from guest_offloads[].
> This will disable all of guest offloads I think ..
No. This doesn't change the dependencies of other features on
_F_GUEST_CSUM. Removing _F_GUEST_CSUM here does not mean that other
features that depend on it will be turned off at the same time, such as
_F_GUEST_TSO{4,6}, F_GUEST_USO{4,6}, etc.
Thanks.
>
>
> > @@ -3522,10 +3521,9 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
> > virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
> > virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||
> > virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO) ||
> > - virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM) ||
> > virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_USO4) ||
> > virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_USO6))) {
> > - NL_SET_ERR_MSG_MOD(extack, "Can't set XDP while host is implementing GRO_HW/CSUM, disable GRO_HW/CSUM first");
> > + NL_SET_ERR_MSG_MOD(extack, "Can't set XDP while host is implementing GRO_HW, disable GRO_HW first");
> > return -EOPNOTSUPP;
> > }
> >
> > --
> > 2.19.1.6.gb485710b
