[PATCH][focal:linux-azure] hv_netvsc: Fix race between VF offering and VF association message from host

[Tim Gardner]

From: Gaurav Kohli <gauravkohli at linux.microsoft.com>

BugLink: https://bugs.launchpad.net/bugs/1994974

commit 365e1ececb2905f94cc10a5817c5b644a32a3ae2 upstream.

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 at vger.kernel.org
Fixes: 00d7ddba11436 ("hv_netvsc: pair VF based on serial number")
Reviewed-by: Haiyang Zhang <haiyangz at microsoft.com>
Signed-off-by: Gaurav Kohli <gauravkohli at linux.microsoft.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(backported from commit 15993e9a9b12487192cbf7eebf838676e05895d5 linux-5.15.y)
[rtg - conflict resolution]
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---

focal/azure Hyperv support is mostly a 5.15 backport, hence the patch from 5.15 stable.

 drivers/net/hyperv/hyperv_net.h |  2 ++
 drivers/net/hyperv/netvsc.c     |  4 ++++
 drivers/net/hyperv/netvsc_drv.c | 19 +++++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 44889c1763b6..0329e9737439 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -975,6 +975,8 @@ struct net_device_context {
 	u32 vf_alloc;
 	/* Serial number of the VF to team with */
 	u32 vf_serial;
+	/* completion variable to confirm vf association */
+	struct completion vf_add;
 
 	/* Used to temporarily save the config info across hibernation */
 	struct netvsc_device_info *saved_netvsc_dev_info;
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index def2adb5217f..a97067f92dd3 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1230,6 +1230,10 @@ static void netvsc_send_vf(struct net_device *ndev,
 
 	net_device_ctx->vf_alloc = nvmsg->msg.v4_msg.vf_assoc.allocated;
 	net_device_ctx->vf_serial = nvmsg->msg.v4_msg.vf_assoc.serial;
+
+	if (net_device_ctx->vf_alloc)
+		complete(&net_device_ctx->vf_add);
+
 	netdev_info(ndev, "VF slot %u %s\n",
 		    net_device_ctx->vf_serial,
 		    net_device_ctx->vf_alloc ? "added" : "removed");
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index c2d752d29898..bb36c5de0db6 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2289,6 +2289,18 @@ 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;
@@ -2366,6 +2378,11 @@ static int netvsc_vf_changed(struct net_device *vf_netdev)
 	if (!netvsc_dev)
 		return NOTIFY_DONE;
 
+	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);
+	}
+
 	netvsc_switch_datapath(ndev, vf_is_up);
 	netdev_info(ndev, "Data path switched %s VF: %s\n",
 		    vf_is_up ? "to" : "from", vf_netdev->name);
@@ -2389,6 +2406,7 @@ 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);
@@ -2426,6 +2444,7 @@ 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);
-- 
2.34.1