The previous reply email has an text format error, please ignore and
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_features
in 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in vhost_dev are out-of-date(may be updated in the next few seconds), so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);
#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);
Split this last chunk into a patch of its own?
--
1.8.3.1
