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

From: Vlad Zolotarov <[email-masked]>
Date: Mon, 30 Mar 2015 15:38:38 +0300

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?

>
>> +	msgbuf[0] = IXGBE_VF_GET_RSS_KEY;
>> +	err = hw->mbx.ops.write_posted(hw, msgbuf, 1);
>> +
>> +	if (err)
>> +		return err;
>> +
>> +	err = hw->mbx.ops.read_posted(hw, msgbuf, 11);
>> +
>> +	if (err)
>> +		return err;
>> +
>> +	msgbuf[0] &= ~IXGBE_VT_MSGTYPE_CTS;
>> +
>> +	/* If the operation has been refused by a PF return -EPERM */
>> +	if (msgbuf[0] == (IXGBE_VF_GET_RETA | IXGBE_VT_MSGTYPE_NACK))
>> +		return -EPERM;
>> +
>> +	/* If we didn't get an ACK there must have been
>> +	 * some sort of mailbox error so we should treat it
>> +	 * as such.
>> +	 */
>> +	if (msgbuf[0] != (IXGBE_VF_GET_RSS_KEY | IXGBE_VT_MSGTYPE_ACK))
>> +		return IXGBE_ERR_MBX;
>> +
>> +	memcpy(rss_key, msgbuf + 1, IXGBEVF_RSS_HASH_KEY_SIZE);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * ixgbevf_get_rss_key - get the RSS Random Key
>> + * @hw: pointer to the HW structure
>> + * @reta: buffer to fill with RETA contents.
>> + *
>> + * The "rss_key" buffer should be big enough to contain 10 registers.
>> + * Ensures the atomicy of a mailbox access using the adapter.mbx_lock spinlock.
>> + *
>> + * Returns: 0 on success.
>> + *          if API doesn't support this operation - (-EPERM).
>> + */
>> +int ixgbevf_get_rss_key(struct ixgbevf_adapter *a, u8 *rss_key)
>> +{
>> +	int rc;
>> +
>> +	spin_lock_bh(&a->mbx_lock);
>> +	rc = ixgbevf_get_rss_key_locked(&a->hw, rss_key);
>> +	spin_unlock_bh(&a->mbx_lock);
>> +
>> +	return rc;
>> +}
>> +
> Since there is currently no cases where you would be getting the rss_key
> without the RETA you might just want to combine this function with
> ixgbevf_get_reta so you only take the lock once and process both
> messages in one pass instead of having to bounce the spinlock.
>
>>   /**
>>    * ixgbevf_get_reta - get the RSS redirection table (RETA) contents.
>>    * @adapter: pointer to the port handle
>> diff --git a/drivers/net/ethernet/intel/ixgbevf/vf.h b/drivers/net/ethernet/intel/ixgbevf/vf.h
>> index 7944962..a054716 100644
>> --- a/drivers/net/ethernet/intel/ixgbevf/vf.h
>> +++ b/drivers/net/ethernet/intel/ixgbevf/vf.h
>> @@ -212,4 +212,5 @@ int ixgbevf_negotiate_api_version(struct ixgbe_hw *hw, int api);
>>   int ixgbevf_get_queues(struct ixgbe_hw *hw, unsigned int *num_tcs,
>>   		       unsigned int *default_tc);
>>   int ixgbevf_get_reta(struct ixgbevf_adapter *adapter, u32 *reta);
>> +int ixgbevf_get_rss_key(struct ixgbevf_adapter *adapter, u8 *rss_key);
>>   #endif /* __IXGBE_VF_H__ */
>>