hv_netvsc: Fix hibernation for mlx5 VF driver

mlx5_suspend()/resume() keep the network interface, so during hibernation
netvsc_unregister_vf() and netvsc_register_vf() are not called, and hence
netvsc_resume() should call netvsc_vf_changed() to switch the data path
back to the VF after hibernation. Note: after we close and re-open the
vmbus channel of the netvsc NIC in netvsc_suspend() and netvsc_resume(),
the data path is implicitly switched to the netvsc NIC. Similarly,
netvsc_suspend() should not call netvsc_unregister_vf(), otherwise the VF
can no longer be used after hibernation.

For mlx4, since the VF network interafce is explicitly destroyed and
re-created during hibernation (see mlx4_suspend()/resume()), hv_netvsc
already explicitly switches the data path from and to the VF automatically
via netvsc_register_vf() and netvsc_unregister_vf(), so mlx4 doesn't need
this fix. Note: mlx4 can still work with the fix because in
netvsc_suspend()/resume() ndev_ctx->vf_netdev is NULL for mlx4.

Fixes: 0efeea5fb153 ("hv_netvsc: Add the support of hibernation")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 64b0a74..81c5c70 100644 (file)
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2587,8 +2587,8 @@ static int netvsc_remove(struct hv_device *dev)
 static int netvsc_suspend(struct hv_device *dev)
 {
        struct net_device_context *ndev_ctx;
-       struct net_device *vf_netdev, *net;
        struct netvsc_device *nvdev;
+       struct net_device *net;
        int ret;
 
        net = hv_get_drvdata(dev);
@@ -2604,10 +2604,6 @@ static int netvsc_suspend(struct hv_device *dev)
                goto out;
        }
 
-       vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
-       if (vf_netdev)
-               netvsc_unregister_vf(vf_netdev);
-
        /* Save the current config info */
        ndev_ctx->saved_netvsc_dev_info = netvsc_devinfo_get(nvdev);
 
@@ -2623,6 +2619,7 @@ static int netvsc_resume(struct hv_device *dev)
        struct net_device *net = hv_get_drvdata(dev);
        struct net_device_context *net_device_ctx;
        struct netvsc_device_info *device_info;
+       struct net_device *vf_netdev;
        int ret;
 
        rtnl_lock();
@@ -2635,6 +2632,15 @@ static int netvsc_resume(struct hv_device *dev)
        netvsc_devinfo_put(device_info);
        net_device_ctx->saved_netvsc_dev_info = NULL;
 
+       /* A NIC driver (e.g. mlx5) may keep the VF network interface across
+        * hibernation, but here the data path is implicitly switched to the
+        * netvsc NIC since the vmbus channel is closed and re-opened, so
+        * netvsc_vf_changed() must be used to switch the data path to the VF.
+        */
+       vf_netdev = rtnl_dereference(net_device_ctx->vf_netdev);
+       if (vf_netdev && netvsc_vf_changed(vf_netdev) != NOTIFY_OK)
+               ret = -EINVAL;
+
        rtnl_unlock();
 
        return ret;