在 2022/11/11 3:00, Michael S. Tsirkin 写道:
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.I'm not sure how is this change even related to what we are trying to do (fix a bug). Explain here?
For this series, all we want to do is to making sure acked_featuresin the NetVhostUserState is credible and uptodate in the scenario that virtio features negotiation and openvswitch service restart happens simultaneously.
To make sure that happens, we save the acked_features to NetVhostUserState right after guest setting virtio-net features.
Assume that we do not save acked_features to NetVhostUserState just as it is, the acked_features in NetVhostUserState has chance to be assigned only when chr_closed_bh/vhost_user_stop happen. Note that openvswitch service stop will cause chr_closed_bh happens and acked_features in vhost_dev will be stored into NetVhostUserState, if the acked_features in vhost_dev are out-of-date(may be updated in the next few seconds), so does the acked_features in NetVhostUserState after doing the assignment, this is the bug.
Let's refine the scenario and derive the bug:
qemu thread dpdk
| |
vhost_net_init() |
| |
assign acked_features in vhost_dev |
with 0x40000000 |
| openvswitch.service stop
chr_closed_bh |
| |
assign acked_features in |
NetVhostUserState with 0x40000000 |
| |
virtio_net_set_features() |
| |
assign acked_features in vhost_dev |
with 0x7060a782 |
| openvswitch.service start
| |
vhost_user_start |
| |
assign acked_features in vhost_dev |
with 0x40000000 |
| |
As the step shows, if we do not keep the acked_features in
NetVhostUserState up-to-date, the acked_features in vhost_dev may be
reloaded with the wrong value(eg, 0x40000000) when vhost_user_start happens.
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)) {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);#endifdiff --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);Split this last chunk into a patch of its own?-- 1.8.3.1
