Re: [PATCH net-next 2/8] net/mlx5: Use v1 response layout for query_esw_functions

[Simon Horman <horms@kernel.org>]

From: 'Simon Horman' <horms@kernel.org>

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---
net/mlx5: Use v1 response layout for query_esw_functions

This patch teaches mlx5_esw_query_functions() to use the v1 response
layout (MLX5_QUERY_ESW_FUNC_OP_MOD_LAYOUT_V1) when the firmware
advertises query_host_net_function_v1, allocates the output buffer
based on query_host_net_function_num_max, and adds a parser for the
new network_function_params layout in mlx5_esw_get_host_pf_info().

> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
> index 861e79ddb489..8b62dde7eb70 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c

[ ... ]

> @@ -1100,12 +1133,55 @@ mlx5_esw_host_pf_from_host_params(const void *entry)
>  	};
>  }
>  
> -struct mlx5_esw_pf_info mlx5_esw_get_host_pf_info(const u32 *out)
> +static struct mlx5_esw_pf_info
> +mlx5_esw_host_pf_from_net_func_params(const u8 *entry, int num_entries)
> +{
> +	int i;
> +
> +	for (i = 0; i < num_entries; i++) {
> +		int pf_type, state;
> +
> +		pf_type = MLX5_GET(network_function_params, entry, pci_pf_type);
> +		if (pf_type != MLX5_PCI_PF_TYPE_EXTERNAL_HOST_PF) {
> +			entry += MLX5_UN_SZ_BYTES(net_function_params);
> +			continue;
> +		}
> +
> +		state = MLX5_GET(network_function_params, entry, vhca_state);
> +
> +		return (struct mlx5_esw_pf_info) {
> +			.pf_disabled = state != MLX5_VHCA_STATE_IN_USE,

[Medium]
The commit message says "this change does not introduce new
functionality," but the legacy parser reads an explicit firmware
host_pf_disabled bit while the v1 parser derives pf_disabled from a
multi-valued vhca_state enum:

  .pf_disabled = state != MLX5_VHCA_STATE_IN_USE,

Is this mapping intended to be exactly equivalent to the legacy
host_pf_disabled bit across all five vhca_state values
(INVALID/ALLOCATED/ACTIVE/IN_USE/TEARDOWN_REQUEST)?

The same vhca_state value is interpreted differently elsewhere in
mlx5 for SFs. mlx5_sf_to_devlink_opstate() in
drivers/net/ethernet/mellanox/mlx5/core/sf/devlink.c reports:

    case MLX5_VHCA_STATE_IN_USE:
    case MLX5_VHCA_STATE_TEARDOWN_REQUEST:
            return DEVLINK_PORT_FN_OPSTATE_ATTACHED;
    case MLX5_VHCA_STATE_INVALID:
    case MLX5_VHCA_STATE_ALLOCATED:
    case MLX5_VHCA_STATE_ACTIVE:
    default:
            return DEVLINK_PORT_FN_OPSTATE_DETACHED;

so SFs in TEARDOWN_REQUEST are reported as ATTACHED, while a host
PF in TEARDOWN_REQUEST would now end up as pf_disabled = true and
therefore DETACHED via mlx5_devlink_pf_port_fn_state_get():

> +			.num_of_vfs = MLX5_GET(network_function_params,
> +					       entry, pci_num_vfs),
> +			.total_vfs = MLX5_GET(network_function_params,
> +					      entry, pci_total_vfs),
> +			.host_number = MLX5_GET(network_function_params,
> +						entry, host_number),
> +		};
> +	}

[Medium]
pf_disabled also feeds esw_vfs_changed_event_handler(), which skips
VF reload when it is true:

> @@ -3716,7 +3716,7 @@ static void esw_vfs_changed_event_handler(struct mlx5_eswitch *esw)
[ ... ]
> -	host_pf_info = mlx5_esw_get_host_pf_info(out);
> +	host_pf_info = mlx5_esw_get_host_pf_info(esw->dev, out);
>  	new_num_vfs = host_pf_info.num_of_vfs;
>  
>  	if (new_num_vfs == esw->esw_funcs.num_vfs || host_pf_info.pf_disabled)

Could the commit message spell out the firmware/PRM mapping between
the legacy host_pf_disabled bit and the vhca_state enum so it is
clear that ACTIVE, ALLOCATED and TEARDOWN_REQUEST really should be
treated as disabled here?

Would it also be worth aligning with mlx5_sf_to_devlink_opstate()
(at least for TEARDOWN_REQUEST) so the devlink opstate reported via
mlx5_devlink_pf_port_fn_state_get() stays consistent between SFs and
host PFs on v1-capable firmware?