[PATCH v3 1/6] vdpa: fix improper error message when adding vdpa dev

[Si-Wei Liu]

In below example, before the fix, mtu attribute is supported
by the parent mgmtdev, but the error message showing "All
provided are not supported" is just misleading.

$ vdpa mgmtdev show
vdpasim_net:
  supported_classes net
  max_supported_vqs 3
  dev_features MTU MAC CTRL_VQ CTRL_MAC_ADDR ANY_LAYOUT VERSION_1 ACCESS_PLATFORM

$ vdpa dev add mgmtdev vdpasim_net name vdpasim0 mtu 5000 max_vqp 2
Error: vdpa: All provided attributes are not supported.
kernel answers: Operation not supported

After fix, the relevant error message will be like:

$ vdpa dev add mgmtdev vdpasim_net name vdpasim0 mtu 5000 max_vqp 2
Error: vdpa: Some provided attributes are not supported: 0x1000.
kernel answers: Operation not supported

Fixes: d8ca2fa5be1b ("vdpa: Enable user to set mac and mtu of vdpa device")
Signed-off-by: Si-Wei Liu <si-wei.liu@xxxxxxxxxx>
Reviewed-by: Parav Pandit <parav@xxxxxxxxxx>
Reviewed-by: Eli Cohen <elic@xxxxxxxxxx>
---
 drivers/vdpa/vdpa.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index 8ef7aa1..3a82ca78 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -622,9 +622,11 @@ static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff *skb, struct genl_info *i
 		err = PTR_ERR(mdev);
 		goto err;
 	}
+
 	if ((config.mask & mdev->config_attr_mask) != config.mask) {
-		NL_SET_ERR_MSG_MOD(info->extack,
-				   "All provided attributes are not supported");
+		NL_SET_ERR_MSG_FMT_MOD(info->extack,
+				       "Some provided attributes are not supported: 0x%llx",
+				       config.mask & ~mdev->config_attr_mask);
 		err = -EOPNOTSUPP;
 		goto err;
 	}
-- 
1.8.3.1