[PATCH V5 3/6] vDPA: allow userspace to query features of a vDPA device

[Zhu Lingshan <lingshan.zhu@xxxxxxxxx>]

This commit adds a new vDPA netlink attribution
VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES. Userspace can query
features of vDPA devices through this new attr.

Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
---
 drivers/vdpa/vdpa.c       | 17 +++++++++++++----
 include/uapi/linux/vdpa.h |  3 +++
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index ebf2f363fbe7..6eb3d972d802 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -491,6 +491,8 @@ static int vdpa_mgmtdev_fill(const struct vdpa_mgmt_dev *mdev, struct sk_buff *m
 		err = -EMSGSIZE;
 		goto msg_err;
 	}
+
+	/* report features of a vDPA management device through VDPA_ATTR_DEV_SUPPORTED_FEATURES */
 	if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_SUPPORTED_FEATURES,
 			      mdev->supported_features, VDPA_ATTR_PAD)) {
 		err = -EMSGSIZE;
@@ -815,7 +817,7 @@ static int vdpa_dev_net_mq_config_fill(struct vdpa_device *vdev,
 static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *msg)
 {
 	struct virtio_net_config config = {};
-	u64 features;
+	u64 features_device, features_driver;
 	u16 val_u16;
 
 	vdpa_get_config_unlocked(vdev, 0, &config, sizeof(config));
@@ -832,12 +834,19 @@ 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 = vdev->config->get_driver_features(vdev);
-	if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features,
+	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);
+
+	/* report features of a vDPA device through VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES */
+	if (nla_put_u64_64bit(msg, VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES, features_device,
 			      VDPA_ATTR_PAD))
 		return -EMSGSIZE;
 
-	return vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
+	return vdpa_dev_net_mq_config_fill(vdev, msg, features_driver, &config);
 }
 
 static int
diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
index 25c55cab3d7c..d171b92ef522 100644
--- a/include/uapi/linux/vdpa.h
+++ b/include/uapi/linux/vdpa.h
@@ -46,7 +46,10 @@ enum vdpa_attr {
 
 	VDPA_ATTR_DEV_NEGOTIATED_FEATURES,	/* u64 */
 	VDPA_ATTR_DEV_MGMTDEV_MAX_VQS,		/* u32 */
+	/* features of a vDPA management device */
 	VDPA_ATTR_DEV_SUPPORTED_FEATURES,	/* u64 */
+	/* features of a vDPA device, e.g., /dev/vhost-vdpa0 */
+	VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES,	/* u64 */
 
 	VDPA_ATTR_DEV_QUEUE_INDEX,              /* u32 */
 	VDPA_ATTR_DEV_VENDOR_ATTR_NAME,		/* string */
-- 
2.31.1