hv_netvsc: Implement support for VF drivers on Hyper-V

Support VF drivers on Hyper-V. On Hyper-V, each VF instance presented to
the guest has an associated synthetic interface that shares the MAC address
with the VF instance. Typically these are bonded together to support
live migration. By default, the host delivers all the incoming packets
on the synthetic interface. Once the VF is up, we need to explicitly switch
the data path on the host to divert traffic onto the VF interface. Even after
switching the data path, broadcast and multicast packets are always delivered
on the synthetic interface and these will have to be injected back onto the
VF interface (if VF is up).
This patch implements the necessary support in netvsc to support Linux
VF drivers.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index c4e1e04..a59cdeb 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1229,6 +1229,9 @@ int rndis_filter_open(struct hv_device *dev)
 	if (!net_device)
 		return -EINVAL;
 
+	if (atomic_inc_return(&net_device->open_cnt) != 1)
+		return 0;
+
 	return rndis_filter_open_device(net_device->extension);
 }
 
@@ -1239,5 +1242,8 @@ int rndis_filter_close(struct hv_device *dev)
 	if (!nvdev)
 		return -EINVAL;
 
+	if (atomic_dec_return(&nvdev->open_cnt) != 0)
+		return 0;
+
 	return rndis_filter_close_device(nvdev->extension);
 }