Subject: Re: [PATCH net-next v9 6/7] ixgbevf: Add RSS Key query code

From: Vlad Zolotarov <[email-masked]>
Date: Mon, 30 Mar 2015 18:31:15 +0300

On 03/30/15 18:07, Alexander Duyck wrote:
>
> On 03/30/2015 05:38 AM, Vlad Zolotarov wrote:
>>
>>
>> On 03/30/15 01:04, Alexander Duyck wrote:
>>> On 03/29/2015 09:11 AM, Vlad Zolotarov wrote:
>>>> Add the ixgbevf_get_rss_key() function that queries the PF for an 
>>>> RSS Random Key
>>>> using a new VF-PF channel IXGBE_VF_GET_RSS_KEY command.
>>>>
>>>> This patch adds the support for 82599 and x540 devices only. 
>>>> Support for other
>>>> devices will be added later.
>>>>
>>>> Signed-off-by: Vlad Zolotarov <[email-masked]>
>>>> ---
>>>> New in v9:
>>>>     - Reduce the support to 82599 and x540 devices only.
>>>>     - Added IXGBEVF_RSS_HASH_KEY_SIZE macro.
>>>>
>>>> New in v8:
>>>>     - Protect a mailbox access.
>>>>
>>>> New in v6:
>>>>     - Return a proper return code when an operation is blocked by PF.
>>>>
>>>> New in v2:
>>>>     - Added a more detailed patch description.
>>>>
>>>> New in v1 (compared to RFC):
>>>>     - Use "if-else" statement instead of a "switch-case" for a 
>>>> single option case
>>>>       (in ixgbevf_get_rss_key()).
>>>> ---
>>>>   drivers/net/ethernet/intel/ixgbevf/ixgbevf.h |  1 +
>>>>   drivers/net/ethernet/intel/ixgbevf/mbx.h     |  1 +
>>>>   drivers/net/ethernet/intel/ixgbevf/vf.c      | 66 
>>>> ++++++++++++++++++++++++++++
>>>>   drivers/net/ethernet/intel/ixgbevf/vf.h      |  1 +
>>>>   4 files changed, 69 insertions(+)
>>>>
>>>> diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h 
>>>> b/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h
>>>> index bc939a1..6771ae3 100644
>>>> --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h
>>>> +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h
>>>> @@ -145,6 +145,7 @@ struct ixgbevf_ring {
>>>>   #define MAX_RX_QUEUES IXGBE_VF_MAX_RX_QUEUES
>>>>   #define MAX_TX_QUEUES IXGBE_VF_MAX_TX_QUEUES
>>>>   #define IXGBEVF_MAX_RSS_QUEUES    2
>>>> +#define IXGBEVF_RSS_HASH_KEY_SIZE    40
>>>>     #define IXGBEVF_DEFAULT_TXD    1024
>>>>   #define IXGBEVF_DEFAULT_RXD    512
>>>> diff --git a/drivers/net/ethernet/intel/ixgbevf/mbx.h 
>>>> b/drivers/net/ethernet/intel/ixgbevf/mbx.h
>>>> index 66e138b..82f44e0 100644
>>>> --- a/drivers/net/ethernet/intel/ixgbevf/mbx.h
>>>> +++ b/drivers/net/ethernet/intel/ixgbevf/mbx.h
>>>> @@ -110,6 +110,7 @@ enum ixgbe_pfvf_api_rev {
>>>>     /* mailbox API, version 1.2 VF requests */
>>>>   #define IXGBE_VF_GET_RETA    0x0a    /* VF request for RETA */
>>>> +#define IXGBE_VF_GET_RSS_KEY    0x0b    /* get RSS hash key */
>>>>     /* length of permanent address message returned from PF */
>>>>   #define IXGBE_VF_PERMADDR_MSG_LEN    4
>>>> diff --git a/drivers/net/ethernet/intel/ixgbevf/vf.c 
>>>> b/drivers/net/ethernet/intel/ixgbevf/vf.c
>>>> index 2676c0b..ec68145 100644
>>>> --- a/drivers/net/ethernet/intel/ixgbevf/vf.c
>>>> +++ b/drivers/net/ethernet/intel/ixgbevf/vf.c
>>>> @@ -301,6 +301,72 @@ static inline int 
>>>> ixgbevf_get_reta_locked(struct ixgbe_hw *hw, u32 *msgbuf,
>>>>       return 0;
>>>>   }
>>>>   +static inline int ixgbevf_get_rss_key_locked(struct ixgbe_hw 
>>>> *hw, u8 *rss_key)
>>>> +{
>>>> +    int err;
>>>> +    u32 msgbuf[IXGBE_VFMAILBOX_SIZE];
>>>> +
>>>> +    /* We currently support the RSS Random Key retrieval for 82599 
>>>> and x540
>>>> +     * devices only.
>>>> +     *
>>>> +     * Thus return an error if API doesn't support RSS Random Key 
>>>> retrieval
>>>> +     * or if the operation is not supported for this device type.
>>>> +     */
>>>> +    if (hw->api_version != ixgbe_mbox_api_12 ||
>>>> +        hw->mac.type >= ixgbe_mac_X550_vf)
>>>> +        return -EPERM;
>>>> +
>>> The return type here should be not supported, or IXGBE_NOT_IMPLEMENTED,
>>> not no permissions.
>>
>> I think a standard EOPNOTSUPP would be a much better choice.
>> Why do u have this ixgbe-specific return values in addition to 
>> standard POSIX ones anyway?
>
> It has to do with being OS agnostic.  If you want to port this to BSD, 
> Linux, DPDK, etc, then you can't always rely on all the error return 
> values being there so there is a tendency to implement your own.  As 
> with the other function you might be best off just returning 
> IXGBE_ERR_MBX since the x550 and API_12 don't support the RSS messages.

Returning the IXGBE_ERR_MBX from the ethtool callback would be the most 
confusing since it is defined to -100 which corresponds to ENETDOWN 
value in Linux. This would result in the most confusing ethtool error 
message.

> - Alex