[RFC PATCH v3 1/3] virtio_net: Introduce VIRTIO_NET_F_BACKUP feature bit

[Sridhar Samudrala <sridhar.samudrala@intel.com>]

This feature bit can be used by hypervisor to indicate virtio_net device to
act as a backup for another device with the same MAC address.

VIRTIO_NET_F_BACKUP is defined as bit 62 as it is a device feature bit.

Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
---
 drivers/net/virtio_net.c        | 2 +-
 include/uapi/linux/virtio_net.h | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 626c27352ae2..bcd13fe906ca 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2920,7 +2920,7 @@ static struct virtio_device_id id_table[] = {
 	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
 	VIRTIO_NET_F_CTRL_MAC_ADDR, \
 	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
-	VIRTIO_NET_F_SPEED_DUPLEX
+	VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_BACKUP
 
 static unsigned int features[] = {
 	VIRTNET_FEATURES,
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index 5de6ed37695b..c7c35fd1a5ed 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -57,6 +57,9 @@
 					 * Steering */
 #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
 
+#define VIRTIO_NET_F_BACKUP	  62	/* Act as backup for another device
+					 * with the same MAC.
+					 */
 #define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Device set linkspeed and duplex */
 
 #ifndef VIRTIO_NET_NO_LEGACY
-- 
2.14.3