Re: [PATCH net-next v2 3/5] psp: add stats from psp spec to driver facing api

[Paolo Abeni <pabeni@redhat.com>]

On 10/28/25 1:00 AM, Daniel Zahka wrote:
> From: Jakub Kicinski <kuba@kernel.org>
> 
> Provide a driver api for reporting device statistics required by the
> "Implementation Requirements" section of the PSP Architecture
> Specification. Use a warning to ensure drivers report stats required
> by the spec.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com>
> ---
>  Documentation/netlink/specs/psp.yaml | 55 ++++++++++++++++++++++++++++
>  include/net/psp/types.h              | 26 +++++++++++++
>  include/uapi/linux/psp.h             |  8 ++++
>  net/psp/psp_main.c                   |  3 +-
>  net/psp/psp_nl.c                     | 22 ++++++++++-
>  5 files changed, 112 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/netlink/specs/psp.yaml b/Documentation/netlink/specs/psp.yaml
> index 914148221384..f3a57782d2cf 100644
> --- a/Documentation/netlink/specs/psp.yaml
> +++ b/Documentation/netlink/specs/psp.yaml
> @@ -98,6 +98,61 @@ attribute-sets:
>            Number of times a socket's Rx got shut down due to using
>            a key which went stale (fully rotated out).
>            Kernel statistic.
> +      -
> +        name: rx-packets
> +        type: uint
> +        doc: |
> +          Number of successfully processed and authenticated PSP packets.
> +          Device statistic (from the PSP spec).
> +      -
> +        name: rx-bytes
> +        type: uint
> +        doc: |
> +          Number of successfully authenticated PSP bytes received, counting from
> +          the first byte after the IV through the last byte of payload.
> +          The fixed initial portion of the PSP header (16 bytes)
> +          and the PSP trailer/ICV (16 bytes) are not included in this count.
> +          Device statistic (from the PSP spec).
> +      -
> +        name: rx-auth-fail
> +        type: uint
> +        doc: |
> +          Number of received PSP packets with unsuccessful authentication.
> +          Device statistic (from the PSP spec).
> +      -
> +        name: rx-error
> +        type: uint
> +        doc: |
> +          Number of received PSP packets with length/framing errors.
> +          Device statistic (from the PSP spec).
> +      -
> +        name: rx-bad
> +        type: uint
> +        doc: |
> +          Number of received PSP packets with miscellaneous errors
> +          (invalid master key indicated by SPI, unsupported version, etc.)
> +          Device statistic (from the PSP spec).
> +      -
> +        name: tx-packets
> +        type: uint
> +        doc: |
> +          Number of successfully processed PSP packets for transmission.
> +          Device statistic (from the PSP spec).
> +      -
> +        name: tx-bytes
> +        type: uint
> +        doc: |
> +          Number of successfully processed PSP bytes for transmit, counting from
> +          the first byte after the IV through the last byte of payload.
> +          The fixed initial portion of the PSP header (16 bytes)
> +          and the PSP trailer/ICV (16 bytes) are not included in this count.
> +          Device statistic (from the PSP spec).
> +      -
> +        name: tx-error
> +        type: uint
> +        doc: |
> +          Number of PSP packets for transmission with errors.
> +          Device statistic (from the PSP spec).
>  
>  operations:
>    list:
> diff --git a/include/net/psp/types.h b/include/net/psp/types.h
> index 5b0ccaac3882..1aa3857a85c1 100644
> --- a/include/net/psp/types.h
> +++ b/include/net/psp/types.h
> @@ -150,6 +150,25 @@ struct psp_assoc {
>  	u8 drv_data[] __aligned(8);
>  };
>  
> +struct psp_dev_stats {
> +	union {
> +		struct {
> +			u64 rx_packets;
> +			u64 rx_bytes;
> +			u64 rx_auth_fail;
> +			u64 rx_error;
> +			u64 rx_bad;
> +			u64 tx_packets;
> +			u64 tx_bytes;
> +			u64 tx_error;
> +		};
> +		DECLARE_FLEX_ARRAY(u64, required);
> +	};
> +	char required_end[0];

This makes static checker unhappy:

/home/cocci/testing/include/net/psp/types.h:167:6-18: WARNING use
flexible-array member instead
(https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)

I think/guess the warning could be avoided using something alike the
following (completely untested!!!):

struct psp_dev_stats {
	struct_group(required,
		union {
			struct {
				u64 rx_packets;
				u64 rx_bytes;
				u64 rx_auth_fail;
				u64 rx_error;
				u64 rx_bad;
				u64 tx_packets;
				u64 tx_bytes;
				u64 tx_error;
			};
			DECLARE_FLEX_ARRAY(u64, required);
		};
	);
};

// ...
const unsigned int required_cnt = sizeof(stats.required) / sizeof(u64);