netdev - [PATCH 2/4] vDPA: only report driver features if FEATURES

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Date:   Fri,  9 Sep 2022 16:57:10 +0800
From:   Zhu Lingshan <lingshan.zhu@...el.com>
To:     jasowang@...hat.com, mst@...hat.com
Cc:     virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        kvm@...r.kernel.org, Zhu Lingshan <lingshan.zhu@...el.com>
Subject: [PATCH 2/4] vDPA: only report driver features if  FEATURES_OK is set

vdpa_dev_net_config_fill() should only report driver features
to userspace after features negotiation is done.

Signed-off-by: Zhu Lingshan <lingshan.zhu@...el.com>
---
 drivers/vdpa/vdpa.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index 798a02c7aa94..29d7e8858e6f 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -819,6 +819,7 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
 	struct virtio_net_config config = {};
 	u64 features_device, features_driver;
 	u16 val_u16;
+	u8 status;
 
 	vdev->config->get_config(vdev, 0, &config, sizeof(config));
 
@@ -834,10 +835,14 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
 	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, val_u16))
 		return -EMSGSIZE;
 
-	features_driver = vdev->config->get_driver_features(vdev);
-	if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features_driver,
-			      VDPA_ATTR_PAD))
-		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) {
+		features_driver = vdev->config->get_driver_features(vdev);
+		if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features_driver,
+				      VDPA_ATTR_PAD))
+			return -EMSGSIZE;
+	}
 
 	features_device = vdev->config->get_device_features(vdev);
 
-- 
2.31.1