The existing code moves VF to the same namespace as the synthetic NIC
during netvsc_register_vf(). But, if the synthetic device is moved to a
new namespace after the VF registration, the VF won't be moved together.

To make the behavior more consistent, add a namespace check for synthetic
NIC's NETDEV_REGISTER event (generated during its move), and move the VF
if it is not in the same namespace.

Cc: stable@vger.kernel.org
Fixes: c0a41b887ce6 ("hv_netvsc: move VF to same namespace as netvsc device")
Suggested-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Simon Horman <horms@kernel.org>
---
v3: Use RCT order as suggested by Simon.
v2: Move my fix to synthetic NIC's NETDEV_REGISTER event as suggested by Stephen.

---
 drivers/net/hyperv/netvsc_drv.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 153b97f8ec0d..23180f7b67b6 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2798,6 +2798,31 @@ static struct  hv_driver netvsc_drv = {
 	},
 };
 
+/* Set VF's namespace same as the synthetic NIC */
+static void netvsc_event_set_vf_ns(struct net_device *ndev)
+{
+	struct net_device_context *ndev_ctx = netdev_priv(ndev);
+	struct net_device *vf_netdev;
+	int ret;
+
+	vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
+	if (!vf_netdev)
+		return;
+
+	if (!net_eq(dev_net(ndev), dev_net(vf_netdev))) {
+		ret = dev_change_net_namespace(vf_netdev, dev_net(ndev),
+					       "eth%d");
+		if (ret)
+			netdev_err(vf_netdev,
+				   "Cannot move to same namespace as %s: %d\n",
+				   ndev->name, ret);
+		else
+			netdev_info(vf_netdev,
+				    "Moved VF to namespace with: %s\n",
+				    ndev->name);
+	}
+}
+
 /*
  * On Hyper-V, every VF interface is matched with a corresponding
  * synthetic interface. The synthetic interface is presented first
@@ -2810,6 +2835,11 @@ static int netvsc_netdev_event(struct notifier_block *this,
 	struct net_device *event_dev = netdev_notifier_info_to_dev(ptr);
 	int ret = 0;
 
+	if (event_dev->netdev_ops == &device_ops && event == NETDEV_REGISTER) {
+		netvsc_event_set_vf_ns(event_dev);
+		return NOTIFY_DONE;
+	}
+
 	ret = check_dev_is_matching_vf(event_dev);
 	if (ret != 0)
 		return NOTIFY_DONE;
-- 
2.34.1

On Fri, Oct 18, 2024 at 11:25:22AM -0700, Haiyang Zhang wrote:
> The existing code moves VF to the same namespace as the synthetic NIC
> during netvsc_register_vf(). But, if the synthetic device is moved to a
> new namespace after the VF registration, the VF won't be moved together.
> 
> To make the behavior more consistent, add a namespace check for synthetic
> NIC's NETDEV_REGISTER event (generated during its move), and move the VF
> if it is not in the same namespace.
> 
> Cc: stable@vger.kernel.org
> Fixes: c0a41b887ce6 ("hv_netvsc: move VF to same namespace as netvsc device")
> Suggested-by: Stephen Hemminger <stephen@networkplumber.org>
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> Reviewed-by: Simon Horman <horms@kernel.org>
> ---
> v3: Use RCT order as suggested by Simon.
> v2: Move my fix to synthetic NIC's NETDEV_REGISTER event as suggested by Stephen.

Thanks, this looks good to me.