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.
kernel answers: Operation not supported

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

Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
---
 drivers/vdpa/vdpa.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index 91eca6d..ff15e0a 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -629,13 +629,20 @@ 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) {
+	if (config.mask && (config.mask & mdev->config_attr_mask) == 0) {
 		NL_SET_ERR_MSG_MOD(info->extack,
 				   "All provided attributes are not supported");
 		err = -EOPNOTSUPP;
 		goto err;
 	}
 
+	if ((config.mask & mdev->config_attr_mask) != config.mask) {
+		NL_SET_ERR_MSG_MOD(info->extack,
+				   "Some provided attributes are not supported");
+		err = -EOPNOTSUPP;
+		goto err;
+	}
+
 	err = mdev->ops->dev_add(mdev, name, &config);
 err:
 	up_write(&vdpa_dev_lock);
-- 
1.8.3.1

On Wed, Oct 19, 2022 at 8:56 AM Si-Wei Liu <si-wei.liu@oracle.com> wrote:
>
> 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.
> kernel answers: Operation not supported
>
> $ vdpa dev add mgmtdev vdpasim_net name vdpasim0 max_vqp 2
> Error: vdpa: All provided attributes are not supported.
> kernel answers: Operation not supported
>
> Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>

Acked-by: Jason Wang <jasowang@redhat.com>

> ---
>  drivers/vdpa/vdpa.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 91eca6d..ff15e0a 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -629,13 +629,20 @@ 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) {
> +       if (config.mask && (config.mask & mdev->config_attr_mask) == 0) {
>                 NL_SET_ERR_MSG_MOD(info->extack,
>                                    "All provided attributes are not supported");
>                 err = -EOPNOTSUPP;
>                 goto err;
>         }
>
> +       if ((config.mask & mdev->config_attr_mask) != config.mask) {
> +               NL_SET_ERR_MSG_MOD(info->extack,
> +                                  "Some provided attributes are not supported");
> +               err = -EOPNOTSUPP;
> +               goto err;
> +       }
> +
>         err = mdev->ops->dev_add(mdev, name, &config);
>  err:
>         up_write(&vdpa_dev_lock);
> --
> 1.8.3.1
>