netdev - Re: [PATCH] igb: Indicate failure on vf reset for empty mac address

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Message-ID: <1412803961.2260.5.camel@jtkirshe-mobl.jf.intel.com>
Date:	Wed, 08 Oct 2014 14:32:41 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	Alexander Graf <agraf@...e.de>
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	Mitch Williams <mitch.a.williams@...el.com>,
	Andy Gospodarek <andy@...yhouse.net>,
	Stefan Assmann <sassmann@...nic.de>,
	Aaron Brown <aaron.f.brown@...el.com>,
	Greg Rose <gregory.v.rose@...el.com>,
	John Ronciak <john.ronciak@...el.com>
Subject: Re: [PATCH] igb: Indicate failure on vf reset for empty mac address

On Wed, 2014-10-08 at 23:23 +0200, Alexander Graf wrote:
> Commit 5ac6f91d changed the igb driver to expose a zero (empty) mac
> address to the VF on reset rather than a random one.
> 
> However, that behavioral change also requires igbvf driver changes
> which can be hard especially when we want to talk to proprietary
> guest OSs.
> 
> Looking at the code previous to the commit in Linux that made igbvf
> work with empty mac addresses (8d56b6d), we can see that on reset
> failure the driver will try to generate a new mac address with both
> the old and the new code.
> 
> Furthermore, ixgbe does send reset failure when it detects an empty
> mac address (35055928c).
> 
> So I think it's safe to make igb behave the same. With this patch I
> can successfully run a Windows 8.1 guest with an empty mac address
> and an assigned igbvf device that has no mac address set by the host.
> 
> If anyone is aware of a guest driver that chokes on NACK returns of
> VF RESET commands, please speak up.
> 
> Signed-off-by: Alexander Graf <agraf@...e.de>
> ---
>  drivers/net/ethernet/intel/igb/igb_main.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
> index cb14bbd..e8c53b6 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -6024,8 +6024,12 @@ static void igb_vf_reset_msg(struct igb_adapter *adapter, u32 vf)
>  	adapter->vf_data[vf].flags |= IGB_VF_FLAG_CTS;
>  
>  	/* reply to reset with ack and vf mac address */
> -	msgbuf[0] = E1000_VF_RESET | E1000_VT_MSGTYPE_ACK;
> -	memcpy(addr, vf_mac, ETH_ALEN);
> +	if (!is_zero_ether_addr(vf_mac)) {
> +		msgbuf[0] = E1000_VF_RESET | E1000_VT_MSGTYPE_ACK;
> +		memcpy(addr, vf_mac, ETH_ALEN);

I know we were using memcpy() before, but shouldn't we convert this to
use the preferred ether_addr_copy()?

> +	} else {
> +		msgbuf[0] = E1000_VF_RESET | E1000_VT_MSGTYPE_NACK;
> +	}
>  	igb_write_mbx(hw, msgbuf, 3, vf);
>  }
>  



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