Re: [PATCH v6 10/13] vdpa: Support reporting max device virtqueues

Add max_supported_vqs field to struct vdpa_mgmt_dev. Upstream drivers
need to feel this value according to the device capabilities.

This value is reported back in a netlink message when showing management
devices.

Examples:

$ vdpa mgmtdev show
auxiliary/mlx5_core.sf.1:
   supported_classes net
   max_supported_vqs 257

$ vdpa -j mgmtdev show
{"mgmtdev":{"auxiliary/mlx5_core.sf.1":{"supported_classes":["net"],"max_supported_vqs":257}}}

$ vdpa -jp mgmtdev show
{
     "mgmtdev": {
         "auxiliary/mlx5_core.sf.1": {
             "supported_classes": [ "net" ],
             "max_supported_vqs": 257
         }
     }
}

Signed-off-by: Eli Cohen <redacted>
---
  drivers/vdpa/vdpa.c       | 3 +++
  include/linux/vdpa.h      | 1 +
  include/uapi/linux/vdpa.h | 1 +
  3 files changed, 5 insertions(+)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index 462da4968270..ea22aa864dd5 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c

@@ -514,6 +514,9 @@ static int vdpa_mgmtdev_fill(const struct vdpa_mgmt_dev *mdev, struct sk_buff *m
  		err = -EMSGSIZE;
  		goto msg_err;
  	}
+	if (nla_put_u32(msg, VDPA_ATTR_DEV_MGMTDEV_MAX_VQS,
+			mdev->max_supported_vqs))
+		goto msg_err;
  
  	genlmsg_end(msg, hdr);
  	return 0;

diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index 47e2b780e4bc..bd75af4feaf7 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h

@@ -448,6 +448,7 @@ struct vdpa_mgmt_dev {
  	const struct virtio_device_id *id_table;
  	u64 config_attr_mask;
  	struct list_head list;
+	u32 max_supported_vqs;
  };
  
  int vdpa_mgmtdev_register(struct vdpa_mgmt_dev *mdev);

diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
index db3738ef3beb..995257c6bf2a 100644
--- a/include/uapi/linux/vdpa.h
+++ b/include/uapi/linux/vdpa.h

@@ -44,6 +44,7 @@ enum vdpa_attr {
  	VDPA_ATTR_DEV_NET_CFG_MTU,		/* u16 */
  
  	VDPA_ATTR_DEV_NEGOTIATED_FEATURES,	/* u64 */
+	VDPA_ATTR_DEV_MGMTDEV_MAX_VQS,		/* u16 */