From mboxrd@z Thu Jan  1 00:00:00 1970
From: John Fastabend <john.r.fastabend@intel.com>
Date: Mon, 18 May 2015 08:55:08 -0700
Subject: [Intel-wired-lan] [net-next PATCH v3 1/2] ethtool: Add helper
 routines to pass vf to rx_flow_spec
In-Reply-To: <555A096D.4040902@redhat.com>
References: <20150518153138.2807.96111.stgit@nitbit.x32>
 <555A096D.4040902@redhat.com>
Message-ID: <555A0B5C.3020204@intel.com>
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To: intel-wired-lan@osuosl.org
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On 05/18/2015 08:46 AM, Alexander Duyck wrote:
> 
> 
> On 05/18/2015 08:31 AM, John Fastabend wrote:
>> The ring_cookie is 64 bits wide which is much larger than can be used
>> for actual queue index values. So provide some helper routines to
>> pack a VF index into the cookie. This is useful to steer packets to
>> a VF ring without having to know the queue layout of the device.
>>
>> Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
>> ---
>>   include/uapi/linux/ethtool.h |   20 ++++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
>> index 2e49fc8..ecc658d 100644
>> --- a/include/uapi/linux/ethtool.h
>> +++ b/include/uapi/linux/ethtool.h
>> @@ -796,6 +796,26 @@ struct ethtool_rx_flow_spec {
>>       __u32        location;
>>   };
>>   +/* How rings are layed out when accessing virtual functions or
>> + * offloaded queues is device specific. To allow users to flow
>> + * steering and specify these queues though break the ring cookie
>> + * into a 32bit queue index with an 8 bit virtual function id.
>> + * This also leaves the 3bytes for further specifiers.
>> + */
>> +#define ETHTOOL_RX_FLOW_SPEC_RING    0x00000000FFFFFFFF
>> +#define ETHTOOL_RX_FLOW_SPEC_RING_VF    0x000000FF00000000
> 
> I still say the VF portion should be more bits. If not 16 then at
> least 12 so that there is room for expansion in the event that
> somebody comes out with a device that supports 256 or more VFs. An
> alternative would be to document that we may want to leave space for
> future expansion of the VF field.

My argument is we don't have these devices today and we can always
extend these later without breaking API because we have 3 unused bytes
here. If we add it now we can't really revert it if we come up with a
better use for the bytes later. I'll add a comment.

> 
>> +#define ETHTOOL_RX_FLOW_SPEC_RING_VF_OFF 32
>> +static inline __u64 ethtool_get_flow_spec_ring(__u64 ring_cookie)
>> +{
>> +    return ETHTOOL_RX_FLOW_SPEC_RING & ring_cookie;
>> +};
>> +
>> +static inline __u64 ethtool_get_flow_spec_ring_vf(__u64 ring_cookie)
>> +{
>> +    return (ETHTOOL_RX_FLOW_SPEC_RING_VF & ring_cookie) >>
>> +                ETHTOOL_RX_FLOW_SPEC_RING_VF_OFF;
>> +};
>> +
>>   /**
>>    * struct ethtool_rxnfc - command to get or set RX flow classification rules
>>    * @cmd: Specific command number - %ETHTOOL_GRXFH, %ETHTOOL_SRXFH,
>>
> 
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