Re: [dpdk-dev] [PATCH v4 1/5] net/virtio: add initial RSS support

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 10/11/21 10:47, Xia, Chenbo wrote:
> Hi Maxime,
> 
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Sent: Monday, October 4, 2021 10:30 PM
>> To: dev@dpdk.org; Xia, Chenbo <chenbo.xia@intel.com>; amorenoz@redhat.com;
>> david.marchand@redhat.com; andrew.rybchenko@oktetlabs.ru; Yigit, Ferruh
>> <ferruh.yigit@intel.com>; michaelba@nvidia.com; viacheslavo@nvidia.com; Li,
>> Xiaoyun <xiaoyun.li@intel.com>
>> Cc: nelio.laranjeiro@6wind.com; yvugenfi@redhat.com; ybendito@redhat.com;
>> Maxime Coquelin <maxime.coquelin@redhat.com>
>> Subject: [PATCH v4 1/5] net/virtio: add initial RSS support
>>
>> Provide the capability to update the hash key, hash types
>> and RETA table on the fly (without needing to stop/start
>> the device). However, the key length and the number of RETA
>> entries are fixed to 40B and 128 entries respectively. This
>> is done in order to simplify the design, but may be
>> revisited later as the Virtio spec provides this
>> flexibility.
>>
>> Note that only VIRTIO_NET_F_RSS support is implemented,
>> VIRTIO_NET_F_HASH_REPORT, which would enable reporting the
>> packet RSS hash calculated by the device into mbuf.rss, is
>> not yet supported.
>>
>> Regarding the default RSS configuration, it has been
>> chosen to use the default Intel ixgbe key as default key,
>> and default RETA is a simple modulo between the hash and
>> the number of Rx queues.
>>
>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>> ---
> 
> [...]
> 
>> +static int
>> +virtio_dev_get_rss_config(struct virtio_hw *hw, uint32_t *rss_hash_types)
>> +{
>> +	struct virtio_net_config local_config;
>> +	struct virtio_net_config *config = &local_config;
>> +
>> +	virtio_read_dev_config(hw,
>> +			offsetof(struct virtio_net_config, rss_max_key_size),
>> +			&config->rss_max_key_size,
>> +			sizeof(config->rss_max_key_size));
>> +	if (config->rss_max_key_size < VIRTIO_NET_RSS_KEY_SIZE) {
>> +		PMD_INIT_LOG(ERR, "Invalid device RSS max key size (%u)",
>> +				config->rss_max_key_size);
>> +		return -EINVAL;
>> +	}
>> +
>> +	virtio_read_dev_config(hw,
>> +			offsetof(struct virtio_net_config,
>> +				rss_max_indirection_table_length),
>> +			&config->rss_max_indirection_table_length,
>> +			sizeof(config->rss_max_indirection_table_length));
>> +	if (config->rss_max_indirection_table_length < VIRTIO_NET_RSS_RETA_SIZE)
>> {
>> +		PMD_INIT_LOG(ERR, "Invalid device RSS max reta size (%u)",
>> +				config->rss_max_indirection_table_length);
>> +		return -EINVAL;
>> +	}
>> +
>> +	virtio_read_dev_config(hw,
>> +			offsetof(struct virtio_net_config, supported_hash_types),
>> +			&config->supported_hash_types,
>> +			sizeof(config->supported_hash_types));
>> +	if ((config->supported_hash_types & VIRTIO_NET_HASH_TYPE_MASK) == 0) {
>> +		PMD_INIT_LOG(ERR, "Invalid device RSS hash types (%u)",
> 
> Better use 0x%x to be more user friendly

Right!

> 
>> +				config->supported_hash_types);
>> +		return -EINVAL;
>> +	}
>> +
>> +	*rss_hash_types = config->supported_hash_types &
>> VIRTIO_NET_HASH_TYPE_MASK;
>> +
>> +	PMD_INIT_LOG(DEBUG, "Device RSS config:");
>> +	PMD_INIT_LOG(DEBUG, "\t-Max key size: %u", config->rss_max_key_size);
>> +	PMD_INIT_LOG(DEBUG, "\t-Max reta size: %u", config-
>>> rss_max_indirection_table_length);
>> +	PMD_INIT_LOG(DEBUG, "\t-Supported hash types: 0x%x", *rss_hash_types);
>> +
>> +	return 0;
>> +}
>> +
>> +static int
>> +virtio_dev_rss_hash_update(struct rte_eth_dev *dev,
>> +		struct rte_eth_rss_conf *rss_conf)
>> +{
>> +	struct virtio_hw *hw = dev->data->dev_private;
>> +	uint16_t nb_queues;
>> +
>> +	if (!virtio_with_feature(hw, VIRTIO_NET_F_RSS))
>> +		return -ENOTSUP;
>> +
>> +	if (rss_conf->rss_hf &
>> ~virtio_to_ethdev_rss_offloads(VIRTIO_NET_HASH_TYPE_MASK))
>> +		return -EINVAL;
>> +
>> +	hw->rss_hash_types = ethdev_to_virtio_rss_offloads(rss_conf->rss_hf);
>> +
>> +	if (rss_conf->rss_key && rss_conf->rss_key_len) {
>> +		if (rss_conf->rss_key_len != VIRTIO_NET_RSS_KEY_SIZE) {
>> +			PMD_INIT_LOG(ERR, "Driver only supports %u RSS key length",
>> +					VIRTIO_NET_RSS_KEY_SIZE);
>> +			return -EINVAL;
>> +		}
>> +		memcpy(hw->rss_key, rss_conf->rss_key, VIRTIO_NET_RSS_KEY_SIZE);
>> +	}
>> +
>> +	nb_queues = RTE_MAX(dev->data->nb_rx_queues, dev->data->nb_tx_queues);
>> +	return virtio_set_multiple_queues_rss(dev, nb_queues);
>> +}
>> +
>> +static int
>> +virtio_dev_rss_hash_conf_get(struct rte_eth_dev *dev,
>> +		struct rte_eth_rss_conf *rss_conf)
>> +{
>> +	struct virtio_hw *hw = dev->data->dev_private;
>> +
>> +	if (!virtio_with_feature(hw, VIRTIO_NET_F_RSS))
>> +		return -ENOTSUP;
>> +
>> +	if (rss_conf->rss_key && rss_conf->rss_key_len >=
>> VIRTIO_NET_RSS_KEY_SIZE)
>> +		memcpy(rss_conf->rss_key, hw->rss_key, VIRTIO_NET_RSS_KEY_SIZE);
>> +	rss_conf->rss_key_len = VIRTIO_NET_RSS_KEY_SIZE;
>> +	rss_conf->rss_hf = virtio_to_ethdev_rss_offloads(hw->rss_hash_types);
>> +
>> +	return 0;
>> +}
>> +
>> +static int virtio_dev_rss_reta_update(struct rte_eth_dev *dev,
>> +			 struct rte_eth_rss_reta_entry64 *reta_conf,
>> +			 uint16_t reta_size)
>> +{
>> +	struct virtio_hw *hw = dev->data->dev_private;
>> +	uint16_t nb_queues;
>> +	int idx, pos, i;
>> +
>> +	if (!virtio_with_feature(hw, VIRTIO_NET_F_RSS))
>> +		return -ENOTSUP;
>> +
>> +	if (reta_size != VIRTIO_NET_RSS_RETA_SIZE)
>> +		return -EINVAL;
>> +
>> +	for (idx = 0, i = 0; i < reta_size; i++) {
> 
> idx is calculated every time. No need to do 'idx = 0'.

That is indeed not necessary, I'll remove it here and below.

>> +		idx = i / RTE_RETA_GROUP_SIZE;
>> +		pos = i % RTE_RETA_GROUP_SIZE;
>> +
>> +		if (((reta_conf[idx].mask >> pos) & 0x1) == 0)
>> +			continue;
>> +
>> +		hw->rss_reta[i] = reta_conf[idx].reta[pos];
>> +	}
>> +
>> +	nb_queues = RTE_MAX(dev->data->nb_rx_queues, dev->data->nb_tx_queues);
>> +	return virtio_set_multiple_queues_rss(dev, nb_queues);
>> +}
>> +
>> +static int virtio_dev_rss_reta_query(struct rte_eth_dev *dev,
>> +			 struct rte_eth_rss_reta_entry64 *reta_conf,
>> +			 uint16_t reta_size)
>> +{
>> +	struct virtio_hw *hw = dev->data->dev_private;
>> +	int idx, i;
>> +
>> +	if (!virtio_with_feature(hw, VIRTIO_NET_F_RSS))
>> +		return -ENOTSUP;
>> +
>> +	if (reta_size != VIRTIO_NET_RSS_RETA_SIZE)
>> +		return -EINVAL;
>> +
>> +	for (idx = 0, i = 0; i < reta_size; i++) {
> 
> Ditto
> 
>> +		idx = i / RTE_RETA_GROUP_SIZE;
>> +		reta_conf[idx].reta[i % RTE_RETA_GROUP_SIZE] = hw->rss_reta[i];
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/*
> 
> [...]
> 
>> +/**
>> + * RSS control
>> + *
>> + * The RSS feature <todo>
>> + */
>> +#define VIRTIO_NET_RSS_RETA_SIZE 128
>> +#define VIRTIO_NET_RSS_KEY_SIZE       40
> 
> Forgot to align the numbers? :)

Yes, I forgot it.

Thanks,
Maxime

> Thanks,
> Chenbo
> 
>> +
>> +struct virtio_net_ctrl_rss {
>> +	uint32_t hash_types;
>> +	uint16_t indirection_table_mask;
>> +	uint16_t unclassified_queue;
>> +	uint16_t indirection_table[VIRTIO_NET_RSS_RETA_SIZE];
>> +	uint16_t max_tx_vq;
>> +	uint8_t hash_key_length;
>> +	uint8_t hash_key_data[VIRTIO_NET_RSS_KEY_SIZE];
>> +};
>> +
>>   /*
>>    * Control link announce acknowledgement
>>    *
>> @@ -292,7 +310,10 @@ struct virtqueue {
>>
>>   /* If multiqueue is provided by host, then we suppport it. */
>>   #define VIRTIO_NET_CTRL_MQ   4
>> +
>>   #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET        0
>> +#define VIRTIO_NET_CTRL_MQ_RSS_CONFIG          1
>> +
>>   #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN        1
>>   #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX        0x8000
>>
>> --
>> 2.31.1
>