On Sun, Oct 30, 2022 at 09:52:39PM +0800, huang...@chinatelecom.cn wrote:
> From: Hyman Huang(黄勇) <huang...@chinatelecom.cn>
>
> Save the acked_features once it be configured by guest
> virtio driver so it can't miss any features.
>
> Note that this patch also change the features saving logic
> in chr_closed_bh, which originally backup features no matter
> whether the features are 0 or not, but now do it only if
> features aren't 0.
>
> As to reset acked_features to 0 if needed, Qemu always
> keeping the backup acked_features up-to-date, and save the
> acked_features after virtio_net_set_features in advance,
> including reset acked_features to 0, so the behavior is
> also covered.
>
> Signed-off-by: Hyman Huang(黄勇) <huang...@chinatelecom.cn>
> Signed-off-by: Guoyi Tu <t...@chinatelecom.cn>
> ---
> hw/net/vhost_net.c | 9 +++++++++
> hw/net/virtio-net.c | 5 +++++
> include/net/vhost_net.h | 2 ++
> net/vhost-user.c | 6 +-----
> 4 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index d28f8b9..2bffc27 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -141,6 +141,15 @@ uint64_t vhost_net_get_acked_features(VHostNetState *net)
> return net->dev.acked_features;
> }
>
> +void vhost_net_save_acked_features(NetClientState *nc)
> +{
> + if (nc->info->type != NET_CLIENT_DRIVER_VHOST_USER) {
> + return;
> + }
> +
> + vhost_user_save_acked_features(nc, false);
> +}
> +
> static int vhost_net_get_fd(NetClientState *backend)
> {
> switch (backend->info->type) {
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index e9f696b..5f8f788 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -924,6 +924,11 @@ static void virtio_net_set_features(VirtIODevice *vdev,
> uint64_t features)
> continue;
> }
> vhost_net_ack_features(get_vhost_net(nc->peer), features);
> + /*
> + * keep acked_features in NetVhostUserState up-to-date so it
> + * can't miss any features configured by guest virtio driver.
> + */
> + vhost_net_save_acked_features(nc->peer);
> }
>
> if (virtio_has_feature(features, VIRTIO_NET_F_CTRL_VLAN)) {
So when do you want to ack features but *not* save them?
Is the effect of this patch, fundamentally, that guest features
from virtio are always copied to vhost-user?
Do we even need an extra copy in vhost user then?
all this came in with:
commit a463215b087c41d7ca94e51aa347cde523831873
Author: Marc-André Lureau <marcandre.lur...@redhat.com>
Date: Mon Jun 6 18:45:05 2016 +0200
vhost-net: save & restore vhost-user acked features
Marc-André do you remember why we have a copy of features in vhost-user
and not just reuse the features from virtio?
> diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
> index 387e913..3a5579b 100644
> --- a/include/net/vhost_net.h
> +++ b/include/net/vhost_net.h
> @@ -46,6 +46,8 @@ int vhost_set_vring_enable(NetClientState * nc, int enable);
>
> uint64_t vhost_net_get_acked_features(VHostNetState *net);
>
> +void vhost_net_save_acked_features(NetClientState *nc);
> +
> int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu);
>
> #endif
> diff --git a/net/vhost-user.c b/net/vhost-user.c
> index 74f349c..c512cc9 100644
> --- a/net/vhost-user.c
> +++ b/net/vhost-user.c
> @@ -258,11 +258,7 @@ static void chr_closed_bh(void *opaque)
> s = DO_UPCAST(NetVhostUserState, nc, ncs[0]);
>
> for (i = queues -1; i >= 0; i--) {
> - s = DO_UPCAST(NetVhostUserState, nc, ncs[i]);
> -
> - if (s->vhost_net) {
> - s->acked_features = vhost_net_get_acked_features(s->vhost_net);
> - }
> + vhost_user_save_acked_features(ncs[i], false);
> }
>
> qmp_set_link(name, false, &err);
> --
> 1.8.3.1
