hv_netvsc: Fix race between VF offering and VF association message from host

During vm boot, there might be possibility that vf registration
call comes before the vf association from host to vm.

And this might break netvsc vf path, To prevent the same block
vf registration until vf bind message comes from host.

Cc: stable@vger.kernel.org
Fixes: 00d7ddba11436 ("hv_netvsc: pair VF based on serial number")
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Gaurav Kohli <gauravkohli@linux.microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 5f08482065ca..89eb4f179a3c 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2313,6 +2313,18 @@ static struct net_device *get_netvsc_byslot(const struct net_device *vf_netdev)
 
 	}
 
+	/* Fallback path to check synthetic vf with
+	 * help of mac addr
+	 */
+	list_for_each_entry(ndev_ctx, &netvsc_dev_list, list) {
+		ndev = hv_get_drvdata(ndev_ctx->device_ctx);
+		if (ether_addr_equal(vf_netdev->perm_addr, ndev->perm_addr)) {
+			netdev_notice(vf_netdev,
+				      "falling back to mac addr based matching\n");
+			return ndev;
+		}
+	}
+
 	netdev_notice(vf_netdev,
 		      "no netdev found for vf serial:%u\n", serial);
 	return NULL;
@@ -2409,6 +2421,11 @@ static int netvsc_vf_changed(struct net_device *vf_netdev, unsigned long event)
 	if (net_device_ctx->data_path_is_vf == vf_is_up)
 		return NOTIFY_OK;
 
+	if (vf_is_up && !net_device_ctx->vf_alloc) {
+		netdev_info(ndev, "Waiting for the VF association from host\n");
+		wait_for_completion(&net_device_ctx->vf_add);
+	}
+
 	ret = netvsc_switch_datapath(ndev, vf_is_up);
 
 	if (ret) {
@@ -2440,6 +2457,7 @@ static int netvsc_unregister_vf(struct net_device *vf_netdev)
 
 	netvsc_vf_setxdp(vf_netdev, NULL);
 
+	reinit_completion(&net_device_ctx->vf_add);
 	netdev_rx_handler_unregister(vf_netdev);
 	netdev_upper_dev_unlink(vf_netdev, ndev);
 	RCU_INIT_POINTER(net_device_ctx->vf_netdev, NULL);
@@ -2479,6 +2497,7 @@ static int netvsc_probe(struct hv_device *dev,
 
 	INIT_DELAYED_WORK(&net_device_ctx->dwork, netvsc_link_change);
 
+	init_completion(&net_device_ctx->vf_add);
 	spin_lock_init(&net_device_ctx->lock);
 	INIT_LIST_HEAD(&net_device_ctx->reconfig_events);
 	INIT_DELAYED_WORK(&net_device_ctx->vf_takeover, netvsc_vf_setup);