Messages in this thread | | | Subject | Re: [PATCH 4/4] tun: indicate support for USO feature | From | Jason Wang <> | Date | Wed, 12 May 2021 09:33:14 +0800 |
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在 2021/5/11 下午4:33, Yuri Benditovich 写道: > On Tue, May 11, 2021 at 9:50 AM Jason Wang <jasowang@redhat.com> wrote: >> >> 在 2021/5/11 下午12:42, Yuri Benditovich 写道: >>> Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com> >>> --- >>> drivers/net/tun.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/net/tun.c b/drivers/net/tun.c >>> index 84f832806313..a35054f9d941 100644 >>> --- a/drivers/net/tun.c >>> +++ b/drivers/net/tun.c >>> @@ -2812,7 +2812,7 @@ static int set_offload(struct tun_struct *tun, unsigned long arg) >>> arg &= ~(TUN_F_TSO4|TUN_F_TSO6); >>> } >>> >>> - arg &= ~TUN_F_UFO; >>> + arg &= ~(TUN_F_UFO|TUN_F_USO); >> >> It looks to me kernel doesn't use "USO", so TUN_F_UDP_GSO_L4 is a better >> name for this > No problem, I can change it in v2 > > and I guess we should toggle NETIF_F_UDP_GSO_l4 here? > > No, we do not, because this indicates only the fact that the guest can > send large UDP packets and have them splitted to UDP segments.
Actually the reverse. The set_offload() controls the tuntap TX path (guest RX path).
When VIRTIO_NET_F_GUEST_XXX was not negotiated, the corresponding netdev features needs to be disabled. When host tries to send those packets to guest, it needs to do software segmentation.
See virtio_net_apply_guest_offloads().
There's currently no way (or not need) to prevent tuntap from receiving GSO packets.
Thanks
> >> And how about macvtap? > We will check how to do that for macvtap. We will send a separate > patch for macvtap or ask for advice. > >> Thanks >> >> >>> } >>> >>> /* This gives the user a way to test for new features in future by
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