[PATCH 4/4] vDPA: Conditionally read MTU and MAC in dev cfg space

[Zhu Lingshan <lingshan.zhu@xxxxxxxxx>]

The spec says:
mtu only exists if VIRTIO_NET_F_MTU is set
The mac address field always exists (though
is only valid if VIRTIO_NET_F_MAC is set)

So vdpa_dev_net_config_fill() should read MTU and MAC
conditionally on the feature bits.

Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
---
 drivers/vdpa/vdpa.c | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index f8ff61232421..b332388d3375 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -815,6 +815,29 @@ static int vdpa_dev_net_mq_config_fill(struct sk_buff *msg, u64 features,
 	return nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP, val_u16);
 }
 
+static int vdpa_dev_net_mtu_config_fill(struct sk_buff *msg, u64 features,
+					const struct virtio_net_config *config)
+{
+	u16 val_u16;
+
+	if ((features & BIT_ULL(VIRTIO_NET_F_MTU)) == 0)
+		return 0;
+
+	val_u16 = __virtio16_to_cpu(true, config->mtu);
+
+	return nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, val_u16);
+}
+
+static int vdpa_dev_net_mac_config_fill(struct sk_buff *msg, u64 features,
+					const struct virtio_net_config *config)
+{
+	if ((features & BIT_ULL(VIRTIO_NET_F_MAC)) == 0)
+		return 0;
+
+	return  nla_put(msg, VDPA_ATTR_DEV_NET_CFG_MACADDR,
+			sizeof(config->mac), config->mac);
+}
+
 static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *msg)
 {
 	struct virtio_net_config config = {};
@@ -824,18 +847,10 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
 
 	vdev->config->get_config(vdev, 0, &config, sizeof(config));
 
-	if (nla_put(msg, VDPA_ATTR_DEV_NET_CFG_MACADDR, sizeof(config.mac),
-		    config.mac))
-		return -EMSGSIZE;
-
 	val_u16 = __virtio16_to_cpu(true, config.status);
 	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_STATUS, val_u16))
 		return -EMSGSIZE;
 
-	val_u16 = __virtio16_to_cpu(true, config.mtu);
-	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, val_u16))
-		return -EMSGSIZE;
-
 	/* only read driver features after the feature negotiation is done */
 	status = vdev->config->get_status(vdev);
 	if (status & VIRTIO_CONFIG_S_FEATURES_OK) {
@@ -852,6 +867,12 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
 			      VDPA_ATTR_PAD))
 		return -EMSGSIZE;
 
+	if (vdpa_dev_net_mtu_config_fill(msg, features_device, &config))
+		return -EMSGSIZE;
+
+	if (vdpa_dev_net_mac_config_fill(msg, features_device, &config))
+		return -EMSGSIZE;
+
 	return vdpa_dev_net_mq_config_fill(msg, features_device, &config);
 }
 
-- 
2.31.1