netdev - RE: [PATCH V2 4/6] vDPA: !FEATURES_OK should not block querying device config space

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Date:   Mon, 13 Jun 2022 20:31:22 +0000
From:   Parav Pandit <parav@...dia.com>
To:     Zhu Lingshan <lingshan.zhu@...el.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "mst@...hat.com" <mst@...hat.com>
CC:     "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "xieyongji@...edance.com" <xieyongji@...edance.com>,
        "gautam.dawar@....com" <gautam.dawar@....com>
Subject: RE: [PATCH V2 4/6] vDPA: !FEATURES_OK should not block querying
 device config space



> From: Zhu Lingshan <lingshan.zhu@...el.com>
> Sent: Monday, June 13, 2022 6:17 AM
> 
> Users may want to query the config space of a vDPA device, to choose a
> appropriate one for a certain guest. This means the users need to read the
> config space before FEATURES_OK, and the existence of config space
> contents does not depend on FEATURES_OK.
> 
> The spec says:
> The device MUST allow reading of any device-specific configuration field
> before FEATURES_OK is set by the driver. This includes fields which are
> conditional on feature bits, as long as those feature bits are offered by the
> device.
> 
> Signed-off-by: Zhu Lingshan <lingshan.zhu@...el.com>
> ---
>  drivers/vdpa/vdpa.c | 8 --------
>  1 file changed, 8 deletions(-)
> 
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c index
> 9b0e39b2f022..d76b22b2f7ae 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -851,17 +851,9 @@ vdpa_dev_config_fill(struct vdpa_device *vdev,
> struct sk_buff *msg, u32 portid,  {
>  	u32 device_id;
>  	void *hdr;
> -	u8 status;
>  	int err;
> 
>  	down_read(&vdev->cf_lock);
> -	status = vdev->config->get_status(vdev);
> -	if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
> -		NL_SET_ERR_MSG_MOD(extack, "Features negotiation not
> completed");
> -		err = -EAGAIN;
> -		goto out;
> -	}
> -
>  	hdr = genlmsg_put(msg, portid, seq, &vdpa_nl_family, flags,
>  			  VDPA_CMD_DEV_CONFIG_GET);
>  	if (!hdr) {
> --
> 2.31.1

Management interface should not mix up the device state machine checks like above.
Hence above code removal is better choice.
Please add fixes tag to this patch.

Reviewed-by: Parav Pandit <parav@...dia.com>