Re: [PATCH net-next V2 3/8] devlink: Extend devlink rate API with traffic classes bandwidth management

[Carolina Jubran <cjubran@nvidia.com>]

On 15/11/2024 9:51, Jiri Pirko wrote:
> Thu, Nov 14, 2024 at 11:09:32PM CET, tariqt@nvidia.com wrote:
>> From: Carolina Jubran <cjubran@nvidia.com>
>>
>> Introduce support for specifying bandwidth proportions between traffic
>> classes (TC) in the devlink-rate API. This new option allows users to
>> allocate bandwidth across multiple traffic classes in a single command.
>>
>> This feature provides a more granular control over traffic management,
>> especially for scenarios requiring Enhanced Transmission Selection.
>>
>> Users can now define a specific bandwidth share for each traffic class,
>> such as allocating 20% for TC0 (TCP/UDP) and 80% for TC5 (RoCE).
>>
>> Example:
>> DEV=pci/0000:08:00.0
>>
>> $ devlink port function rate add $DEV/vfs_group tx_share 10Gbit \
>>   tx_max 50Gbit tc-bw 0:20 1:0 2:0 3:0 4:0 5:80 6:0 7:0
>>
>> $ devlink port function rate set $DEV/vfs_group \
>>   tc-bw 0:20 1:0 2:0 3:0 4:0 5:10 6:60 7:0
>>
>> Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
>> Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
>> Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
>> ---
>> Documentation/netlink/specs/devlink.yaml | 22 ++++++++
>> include/net/devlink.h                    |  7 +++
>> include/uapi/linux/devlink.h             |  4 ++
>> net/devlink/netlink_gen.c                | 15 +++--
>> net/devlink/netlink_gen.h                |  1 +
>> net/devlink/rate.c                       | 71 +++++++++++++++++++++++-
>> 6 files changed, 113 insertions(+), 7 deletions(-)
>>
>> diff --git a/Documentation/netlink/specs/devlink.yaml b/Documentation/netlink/specs/devlink.yaml
>> index 09fbb4c03fc8..68211b8218fd 100644
>> --- a/Documentation/netlink/specs/devlink.yaml
>> +++ b/Documentation/netlink/specs/devlink.yaml
>> @@ -817,6 +817,16 @@ attribute-sets:
>>        -
>>          name: rate-tx-weight
>>          type: u32
>> +      -
>> +        name: rate-tc-index
>> +        type: u8
>> +
>> +      - name: rate-bw
> 
> This is bandwidth of tc. The name therefore should be "rate-tc-bw".
> Could you also document units of this attr value?
> 
>

I will rename it to rate-tc-bw and update the documentation to include 
the valid range (0-100).

>> +        type: u32
>> +      -
>> +        name: rate-tc-bw
>> +        type: nest
>> +        nested-attributes: dl-rate-tc-bw
>>        -
>>          name: region-direct
>>          type: flag
>> @@ -1225,6 +1235,16 @@ attribute-sets:
>>        -
>>          name: flash
>>          type: flag
>> +  -
>> +    name: dl-rate-tc-bw
>> +    subset-of: devlink
>> +    attributes:
>> +      -
>> +        name: rate-tc-index
>> +        type: u8
>> +      -
>> +        name: rate-bw
>> +        type: u32
>>
>> operations:
>>    enum-model: directional
>> @@ -2148,6 +2168,7 @@ operations:
>>              - rate-tx-max
>>              - rate-tx-priority
>>              - rate-tx-weight
>> +            - rate-tc-bw
>>              - rate-parent-node-name
>>
>>      -
>> @@ -2168,6 +2189,7 @@ operations:
>>              - rate-tx-max
>>              - rate-tx-priority
>>              - rate-tx-weight
>> +            - rate-tc-bw
>>              - rate-parent-node-name
>>
>>      -
>> diff --git a/include/net/devlink.h b/include/net/devlink.h
>> index fbb9a2668e24..277b826cdd60 100644
>> --- a/include/net/devlink.h
>> +++ b/include/net/devlink.h
>> @@ -20,6 +20,7 @@
>> #include <uapi/linux/devlink.h>
>> #include <linux/xarray.h>
>> #include <linux/firmware.h>
>> +#include <linux/dcbnl.h>
>>
>> struct devlink;
>> struct devlink_linecard;
>> @@ -117,6 +118,8 @@ struct devlink_rate {
>>
>> 	u32 tx_priority;
>> 	u32 tx_weight;
>> +
>> +	u32 tc_bw[IEEE_8021QAZ_MAX_TCS];
>> };
>>
>> struct devlink_port {
>> @@ -1469,6 +1472,8 @@ struct devlink_ops {
>> 					 u32 tx_priority, struct netlink_ext_ack *extack);
>> 	int (*rate_leaf_tx_weight_set)(struct devlink_rate *devlink_rate, void *priv,
>> 				       u32 tx_weight, struct netlink_ext_ack *extack);
>> +	int (*rate_leaf_tc_bw_set)(struct devlink_rate *devlink_rate, void *priv,
>> +				   u32 *tc_bw, struct netlink_ext_ack *extack);
>> 	int (*rate_node_tx_share_set)(struct devlink_rate *devlink_rate, void *priv,
>> 				      u64 tx_share, struct netlink_ext_ack *extack);
>> 	int (*rate_node_tx_max_set)(struct devlink_rate *devlink_rate, void *priv,
>> @@ -1477,6 +1482,8 @@ struct devlink_ops {
>> 					 u32 tx_priority, struct netlink_ext_ack *extack);
>> 	int (*rate_node_tx_weight_set)(struct devlink_rate *devlink_rate, void *priv,
>> 				       u32 tx_weight, struct netlink_ext_ack *extack);
>> +	int (*rate_node_tc_bw_set)(struct devlink_rate *devlink_rate, void *priv,
>> +				   u32 *tc_bw, struct netlink_ext_ack *extack);
>> 	int (*rate_node_new)(struct devlink_rate *rate_node, void **priv,
>> 			     struct netlink_ext_ack *extack);
>> 	int (*rate_node_del)(struct devlink_rate *rate_node, void *priv,
>> diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
>> index 9401aa343673..a66217808dd9 100644
>> --- a/include/uapi/linux/devlink.h
>> +++ b/include/uapi/linux/devlink.h
>> @@ -614,6 +614,10 @@ enum devlink_attr {
>>
>> 	DEVLINK_ATTR_REGION_DIRECT,		/* flag */
>>
>> +	DEVLINK_ATTR_RATE_TC_INDEX,		/* u8 */
>> +	DEVLINK_ATTR_RATE_BW,			/* u32 */
>> +	DEVLINK_ATTR_RATE_TC_BW,		/* nested */
>> +
>> 	/* Add new attributes above here, update the spec in
>> 	 * Documentation/netlink/specs/devlink.yaml and re-generate
>> 	 * net/devlink/netlink_gen.c.
>> diff --git a/net/devlink/netlink_gen.c b/net/devlink/netlink_gen.c
>> index f9786d51f68f..fac062ede7a4 100644
>> --- a/net/devlink/netlink_gen.c
>> +++ b/net/devlink/netlink_gen.c
>> @@ -18,6 +18,11 @@ const struct nla_policy devlink_dl_port_function_nl_policy[DEVLINK_PORT_FN_ATTR_
>> 	[DEVLINK_PORT_FN_ATTR_CAPS] = NLA_POLICY_BITFIELD32(15),
>> };
>>
>> +const struct nla_policy devlink_dl_rate_tc_bw_nl_policy[DEVLINK_ATTR_RATE_BW + 1] = {
>> +	[DEVLINK_ATTR_RATE_TC_INDEX] = { .type = NLA_U8, },
>> +	[DEVLINK_ATTR_RATE_BW] = { .type = NLA_U32, },
>> +};
>> +
>> const struct nla_policy devlink_dl_selftest_id_nl_policy[DEVLINK_ATTR_SELFTEST_ID_FLASH + 1] = {
>> 	[DEVLINK_ATTR_SELFTEST_ID_FLASH] = { .type = NLA_FLAG, },
>> };
>> @@ -496,7 +501,7 @@ static const struct nla_policy devlink_rate_get_dump_nl_policy[DEVLINK_ATTR_DEV_
>> };
>>
>> /* DEVLINK_CMD_RATE_SET - do */
>> -static const struct nla_policy devlink_rate_set_nl_policy[DEVLINK_ATTR_RATE_TX_WEIGHT + 1] = {
>> +static const struct nla_policy devlink_rate_set_nl_policy[DEVLINK_ATTR_RATE_TC_BW + 1] = {
>> 	[DEVLINK_ATTR_BUS_NAME] = { .type = NLA_NUL_STRING, },
>> 	[DEVLINK_ATTR_DEV_NAME] = { .type = NLA_NUL_STRING, },
>> 	[DEVLINK_ATTR_RATE_NODE_NAME] = { .type = NLA_NUL_STRING, },
>> @@ -504,11 +509,12 @@ static const struct nla_policy devlink_rate_set_nl_policy[DEVLINK_ATTR_RATE_TX_W
>> 	[DEVLINK_ATTR_RATE_TX_MAX] = { .type = NLA_U64, },
>> 	[DEVLINK_ATTR_RATE_TX_PRIORITY] = { .type = NLA_U32, },
>> 	[DEVLINK_ATTR_RATE_TX_WEIGHT] = { .type = NLA_U32, },
>> +	[DEVLINK_ATTR_RATE_TC_BW] = NLA_POLICY_NESTED(devlink_dl_rate_tc_bw_nl_policy),
>> 	[DEVLINK_ATTR_RATE_PARENT_NODE_NAME] = { .type = NLA_NUL_STRING, },
>> };
>>
>> /* DEVLINK_CMD_RATE_NEW - do */
>> -static const struct nla_policy devlink_rate_new_nl_policy[DEVLINK_ATTR_RATE_TX_WEIGHT + 1] = {
>> +static const struct nla_policy devlink_rate_new_nl_policy[DEVLINK_ATTR_RATE_TC_BW + 1] = {
>> 	[DEVLINK_ATTR_BUS_NAME] = { .type = NLA_NUL_STRING, },
>> 	[DEVLINK_ATTR_DEV_NAME] = { .type = NLA_NUL_STRING, },
>> 	[DEVLINK_ATTR_RATE_NODE_NAME] = { .type = NLA_NUL_STRING, },
>> @@ -516,6 +522,7 @@ static const struct nla_policy devlink_rate_new_nl_policy[DEVLINK_ATTR_RATE_TX_W
>> 	[DEVLINK_ATTR_RATE_TX_MAX] = { .type = NLA_U64, },
>> 	[DEVLINK_ATTR_RATE_TX_PRIORITY] = { .type = NLA_U32, },
>> 	[DEVLINK_ATTR_RATE_TX_WEIGHT] = { .type = NLA_U32, },
>> +	[DEVLINK_ATTR_RATE_TC_BW] = NLA_POLICY_NESTED(devlink_dl_rate_tc_bw_nl_policy),
>> 	[DEVLINK_ATTR_RATE_PARENT_NODE_NAME] = { .type = NLA_NUL_STRING, },
>> };
>>
>> @@ -1164,7 +1171,7 @@ const struct genl_split_ops devlink_nl_ops[74] = {
>> 		.doit		= devlink_nl_rate_set_doit,
>> 		.post_doit	= devlink_nl_post_doit,
>> 		.policy		= devlink_rate_set_nl_policy,
>> -		.maxattr	= DEVLINK_ATTR_RATE_TX_WEIGHT,
>> +		.maxattr	= DEVLINK_ATTR_RATE_TC_BW,
>> 		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
>> 	},
>> 	{
>> @@ -1174,7 +1181,7 @@ const struct genl_split_ops devlink_nl_ops[74] = {
>> 		.doit		= devlink_nl_rate_new_doit,
>> 		.post_doit	= devlink_nl_post_doit,
>> 		.policy		= devlink_rate_new_nl_policy,
>> -		.maxattr	= DEVLINK_ATTR_RATE_TX_WEIGHT,
>> +		.maxattr	= DEVLINK_ATTR_RATE_TC_BW,
>> 		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
>> 	},
>> 	{
>> diff --git a/net/devlink/netlink_gen.h b/net/devlink/netlink_gen.h
>> index 8f2bd50ddf5e..df37c3ef3113 100644
>> --- a/net/devlink/netlink_gen.h
>> +++ b/net/devlink/netlink_gen.h
>> @@ -13,6 +13,7 @@
>>
>> /* Common nested types */
>> extern const struct nla_policy devlink_dl_port_function_nl_policy[DEVLINK_PORT_FN_ATTR_CAPS + 1];
>> +extern const struct nla_policy devlink_dl_rate_tc_bw_nl_policy[DEVLINK_ATTR_RATE_BW + 1];
>> extern const struct nla_policy devlink_dl_selftest_id_nl_policy[DEVLINK_ATTR_SELFTEST_ID_FLASH + 1];
>>
>> /* Ops table for devlink */
>> diff --git a/net/devlink/rate.c b/net/devlink/rate.c
>> index 8828ffaf6cbc..dbf1d552fae2 100644
>> --- a/net/devlink/rate.c
>> +++ b/net/devlink/rate.c
>> @@ -86,7 +86,9 @@ static int devlink_nl_rate_fill(struct sk_buff *msg,
>> 				int flags, struct netlink_ext_ack *extack)
>> {
>> 	struct devlink *devlink = devlink_rate->devlink;
>> +	struct nlattr *nla_tc_bw;
>> 	void *hdr;
>> +	int i;
>>
>> 	hdr = genlmsg_put(msg, portid, seq, &devlink_nl_family, flags, cmd);
>> 	if (!hdr)
>> @@ -124,10 +126,29 @@ static int devlink_nl_rate_fill(struct sk_buff *msg,
>> 			devlink_rate->tx_weight))
>> 		goto nla_put_failure;
>>
>> -	if (devlink_rate->parent)
>> -		if (nla_put_string(msg, DEVLINK_ATTR_RATE_PARENT_NODE_NAME,
>> -				   devlink_rate->parent->name))
>> +	nla_tc_bw = nla_nest_start(msg, DEVLINK_ATTR_RATE_TC_BW);
>> +	if (!nla_tc_bw)
>> +		goto nla_put_failure;
>> +
>> +	for (i = 0; i < IEEE_8021QAZ_MAX_TCS; i++) {
> 
> Wait, so you fill this up unconditionally? I mean, for set you check if
> the driver supports it. For get you always fill this up? That looks
> wrong. Any reason to do so?
> 
>

I followed the existing pattern in devlink, where attributes like 
tx_share and tx_weight are filled unconditionally in the get operation.
Should I still add a check to see if tc_bw_set is supported?

>> +		struct nlattr *nla_tc_entry = nla_nest_start(msg, i);
>> +
>> +		if (!nla_tc_entry) {
>> +			nla_nest_cancel(msg, nla_tc_bw);
>> +			goto nla_put_failure;
>> +		}
>> +
>> +		if (nla_put_u8(msg, DEVLINK_ATTR_RATE_TC_INDEX, i) ||
>> +		    nla_put_u32(msg, DEVLINK_ATTR_RATE_BW, devlink_rate->tc_bw[i])) {
>> +			nla_nest_cancel(msg, nla_tc_entry);
>> +			nla_nest_cancel(msg, nla_tc_bw);
>> 			goto nla_put_failure;
>> +		}
>> +
>> +		nla_nest_end(msg, nla_tc_entry);
>> +	}
>> +
>> +	nla_nest_end(msg, nla_tc_bw);
>>
>> 	genlmsg_end(msg, hdr);
>> 	return 0;
>> @@ -380,6 +401,38 @@ static int devlink_nl_rate_set(struct devlink_rate *devlink_rate,
>> 		devlink_rate->tx_weight = weight;
>> 	}
>>
>> +	if (attrs[DEVLINK_ATTR_RATE_TC_BW]) {
>> +		struct nlattr *nla_tc_bw = attrs[DEVLINK_ATTR_RATE_TC_BW];
>> +		struct nlattr *tb[DEVLINK_ATTR_RATE_BW + 1];
>> +		u32 tc_bw[IEEE_8021QAZ_MAX_TCS] = {0};
>> +		struct nlattr *nla_tc_entry;
>> +		int rem, tc_index;
>> +
>> +		nla_for_each_nested(nla_tc_entry, nla_tc_bw, rem) {
>> +			err = nla_parse_nested(tb, DEVLINK_ATTR_RATE_BW, nla_tc_entry,
>> +					       devlink_dl_rate_tc_bw_nl_policy, info->extack);
>> +			if (err)
>> +				return err;
>> +
>> +			if (tb[DEVLINK_ATTR_RATE_TC_INDEX] && tb[DEVLINK_ATTR_RATE_BW]) {
>> +				tc_index = nla_get_u8(tb[DEVLINK_ATTR_RATE_TC_INDEX]);
> 
> Ough, you trust user to provide you index to array. Recipe for disaster.
> NLA_POLICY_RANGE() for tc-index would sanitize this. Btw, you use nested
> array to carry rate-bw and tc-index attrs, isn't the array index good
> enough? Then you can avoid tc-index attr (which in most cases holds
> redundant index value). Or do you expect userspace to pass only partial
> set of tcs?
> 
>

I will drop the tc-index attribute as it is redundant. To address your 
question: I expect userspace to always provide a complete set of tcs.

>> +				tc_bw[tc_index] = nla_get_u32(tb[DEVLINK_ATTR_RATE_BW]);
>> +			}
>> +		}
>> +
>> +		if (devlink_rate_is_leaf(devlink_rate))
>> +			err = ops->rate_leaf_tc_bw_set(devlink_rate, devlink_rate->priv,
>> +						       tc_bw, info->extack);
>> +		else if (devlink_rate_is_node(devlink_rate))
>> +			err = ops->rate_node_tc_bw_set(devlink_rate, devlink_rate->priv,
>> +						       tc_bw, info->extack);
>> +
>> +		if (err)
>> +			return err;
>> +
>> +		memcpy(devlink_rate->tc_bw, tc_bw, sizeof(tc_bw));
>> +	}
>> +
>> 	nla_parent = attrs[DEVLINK_ATTR_RATE_PARENT_NODE_NAME];
>> 	if (nla_parent) {
>> 		err = devlink_nl_rate_parent_node_set(devlink_rate, info,
>> @@ -423,6 +476,12 @@ static bool devlink_rate_set_ops_supported(const struct devlink_ops *ops,
>> 					    "TX weight set isn't supported for the leafs");
>> 			return false;
>> 		}
>> +		if (attrs[DEVLINK_ATTR_RATE_TC_BW] && !ops->rate_leaf_tc_bw_set) {
>> +			NL_SET_ERR_MSG_ATTR(info->extack,
>> +					    attrs[DEVLINK_ATTR_RATE_TC_BW],
>> +					    "TC bandwidth set isn't supported for the leafs");
>> +			return false;
>> +		}
>> 	} else if (type == DEVLINK_RATE_TYPE_NODE) {
>> 		if (attrs[DEVLINK_ATTR_RATE_TX_SHARE] && !ops->rate_node_tx_share_set) {
>> 			NL_SET_ERR_MSG(info->extack, "TX share set isn't supported for the nodes");
>> @@ -449,6 +508,12 @@ static bool devlink_rate_set_ops_supported(const struct devlink_ops *ops,
>> 					    "TX weight set isn't supported for the nodes");
>> 			return false;
>> 		}
>> +		if (attrs[DEVLINK_ATTR_RATE_TC_BW] && !ops->rate_node_tc_bw_set) {
>> +			NL_SET_ERR_MSG_ATTR(info->extack,
>> +					    attrs[DEVLINK_ATTR_RATE_TC_BW],
>> +					    "TC bandwidth set isn't supported for the nodes");
>> +			return false;
>> +		}
>> 	} else {
>> 		WARN(1, "Unknown type of rate object");
>> 		return false;
>> -- 
>> 2.44.0
>>