RE: [PATCH] net/ixgbe: consider DCB/VMDq conf when getting RSS conf

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Min Zhou <zhoumin@loongson.cn>
> Sent: Wednesday, April 12, 2023 6:02 PM
> To: Yang, Qiming <qiming.yang@intel.com>; Wu, Wenjun1
> <wenjun1.wu@intel.com>; zhoumin@loongson.cn
> Cc: dev@dpdk.org; maobibo@loongson.cn
> Subject: [PATCH] net/ixgbe: consider DCB/VMDq conf when getting RSS conf
> 
> The mrqe field of MRQC register is an enum. From the Intel 82599 datasheet,
> we know that these values below for the mrqe field are all related to RSS
> configuration:
> 	0000b = RSS disabled.
> 	0001b = RSS only -- Single set of RSS 16 queues.
> 	0010b = DCB enabled and RSS disabled -- 8 TCs, each allocated 1
> queue.
> 	0011b = DCB enabled and RSS disabled -- 4 TCs, each allocated 1
> queue.
> 	0100b = DCB and RSS -- 8 TCs, each allocated 16 RSS queues.
> 	0101b = DCB and RSS -- 4 TCs, each allocated 16 RSS queues.
> 	1000b = Virtualization only -- 64 pools, no RSS, each pool allocated
> 		2 queues.
> 	1010b = Virtualization and RSS -- 32 pools, each allocated 4 RSS
> queues.
> 	1011b = Virtualization and RSS -- 64 pools, each allocated 2 RSS
> queues.
> 
> The ixgbe pmd will check whether the rss is enabled or not when getting rss
> conf. So, beside comparing the value of mrqe field with xxx0b and xxx1b, we
> also needto consider the other configurations, such as DCB + RSS or VMDQ +
> RSS. Otherwise, we may not get the correct rss conf in some cases, such as
> when we use DCB and RSS with 8 TCs which corresponds to 0100b for the
> mrqe field.
> 
> Signed-off-by: Min Zhou <zhoumin@loongson.cn>
> ---
>  drivers/net/ixgbe/ixgbe_rxtx.c | 91 ++++++++++++++++++++++++++++++----
>  1 file changed, 80 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
> index c9d6ca9efe..1eff0053ed 100644
> --- a/drivers/net/ixgbe/ixgbe_rxtx.c
> +++ b/drivers/net/ixgbe/ixgbe_rxtx.c
> @@ -3461,18 +3461,89 @@ static uint8_t rss_intel_key[40] = {
>  	0x6A, 0x42, 0xB7, 0x3B, 0xBE, 0xAC, 0x01, 0xFA,  };
> 
> +/*
> + * This function removes the rss configuration in the mrqe field of
> +MRQC
> + * register and tries to maintain other configurations in the field,
> +such
> + * DCB and Virtualization.
> + *
> + * The MRQC register supplied in section 7.1.2.8.3 of the Intel 82599
> datasheet.
> + * From the datasheet, we know that the mrqe field is an enum. So,
> +masking the
> + * mrqe field with '~IXGBE_MRQC_RSSEN' may not completely disable rss
> + * configuration. For example, the value of mrqe is equal to 0101b when
> +DCB and
> + * RSS with 4 TCs configured, however 'mrqe &= ~0x01' is equal to 0100b
> +which
> + * corresponds to DCB and RSS with 8 TCs.
> + */
> +static void
> +ixgbe_mrqc_rss_remove(struct ixgbe_hw *hw) {
> +	uint32_t mrqc;
> +	uint32_t mrqc_reg;
> +	uint32_t mrqe_val;
> +
> +	mrqc_reg = ixgbe_mrqc_reg_get(hw->mac.type);
> +	mrqc = IXGBE_READ_REG(hw, mrqc_reg);
> +	mrqe_val = mrqc & IXGBE_MRQC_MRQE_MASK;
> +
> +	switch (mrqe_val) {
> +	case IXGBE_MRQC_RSSEN:
> +		/* Completely disable rss */
> +		mrqe_val = 0;
> +		break;
> +	case IXGBE_MRQC_RTRSS8TCEN:
> +		mrqe_val = IXGBE_MRQC_RT8TCEN;
> +		break;
> +	case IXGBE_MRQC_RTRSS4TCEN:
> +		mrqe_val = IXGBE_MRQC_RT4TCEN;
> +		break;
> +	case IXGBE_MRQC_VMDQRSS64EN:
> +	/* FIXME. Can 32 pools with rss convert to 64 pools without rss? */
> +	case IXGBE_MRQC_VMDQRSS32EN:

better not change the pool number, can we just print a warning and break?

Otherwise
Acked-by: Qi Zhang <qi.z.zhang@intel.com>