[PATCH 5.10] hv_netvsc: Fix race between VF offering and VF association message from host

[PATCH 5.10] hv_netvsc: Fix race between VF offering and VF association message from host

[Gaurav Kohli]

[ Upstream commit 365e1ececb2905f94cc10a5817c5b644a32a3ae2 ]

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>
---
 drivers/net/hyperv/hyperv_net.h |  3 ++-
 drivers/net/hyperv/netvsc.c     |  4 ++++
 drivers/net/hyperv/netvsc_drv.c | 20 ++++++++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index a0f338cf1424..367878493e70 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -977,7 +977,8 @@ 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;
 	/* Is the current data path through the VF NIC? */
 	bool  data_path_is_vf;
 
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 0c3de94b5178..f813ec586049 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1324,6 +1324,10 @@ 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 261e6e55a907..db6e2f8cc16e 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2287,6 +2287,7 @@ static struct net_device *get_netvsc_byslot(const struct net_device *vf_netdev)
 {
 	struct device *parent = vf_netdev->dev.parent;
 	struct net_device_context *ndev_ctx;
+	struct net_device *ndev;
 	struct pci_dev *pdev;
 	u32 serial;
 
@@ -2313,6 +2314,18 @@ static struct net_device *get_netvsc_byslot(const struct net_device *vf_netdev)
 			return hv_get_drvdata(ndev_ctx->device_ctx);
 	}
 
+	/* 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;
@@ -2403,6 +2416,11 @@ static int netvsc_vf_changed(struct net_device *vf_netdev)
 		return NOTIFY_OK;
 	net_device_ctx->data_path_is_vf = vf_is_up;
 
+	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);
@@ -2426,6 +2444,7 @@ 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);
@@ -2463,6 +2482,7 @@ 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);
-- 
2.25.1

Re: [PATCH 5.10] hv_netvsc: Fix race between VF offering and VF association message from host

[Greg KH]

On Wed, Oct 26, 2022 at 06:23:43AM -0700, Gaurav Kohli wrote:
> [ Upstream commit 365e1ececb2905f94cc10a5817c5b644a32a3ae2 ]
> 
> 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>
> ---
>  drivers/net/hyperv/hyperv_net.h |  3 ++-
>  drivers/net/hyperv/netvsc.c     |  4 ++++
>  drivers/net/hyperv/netvsc_drv.c | 20 ++++++++++++++++++++
>  3 files changed, 26 insertions(+), 1 deletion(-)

Now queued up, thanks.

greg k-h