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

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Date:	Thu, 9 Oct 2014 00:03:55 +0200
From:	Alexander Graf <agraf@...e.de>
To:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <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




> Am 08.10.2014 um 23:32 schrieb Jeff Kirsher <jeffrey.t.kirsher@...el.com>:
> 
>> 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()?

Sure, but don't you think a coccinelle script across the intel drivers would be better than single spot changes? ;)

Alex

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