psp: add stats from psp spec to driver facing api

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: Daniel Zahka <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/netlink/specs/psp.yaml

···
           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:

include/net/psp/types.h

···
 	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);
+	};
+};
+
 /**
  * struct psp_dev_ops - netdev driver facing PSP callbacks
  */
···
 	 * Remove an association from the device.
 	 */
 	void (*tx_key_del)(struct psp_dev *psd, struct psp_assoc *pas);
+
+	/**
+	 * @get_stats: get statistics from the device
+	 * Stats required by the spec must be maintained and filled in.
+	 * Stats must be filled in member-by-member, never memset the struct.
+	 */
+	void (*get_stats)(struct psp_dev *psd, struct psp_dev_stats *stats);
 };
 
 #endif /* __NET_PSP_H */

include/uapi/linux/psp.h

···
 	PSP_A_STATS_DEV_ID = 1,
 	PSP_A_STATS_KEY_ROTATIONS,
 	PSP_A_STATS_STALE_EVENTS,
+	PSP_A_STATS_RX_PACKETS,
+	PSP_A_STATS_RX_BYTES,
+	PSP_A_STATS_RX_AUTH_FAIL,
+	PSP_A_STATS_RX_ERROR,
+	PSP_A_STATS_RX_BAD,
+	PSP_A_STATS_TX_PACKETS,
+	PSP_A_STATS_TX_BYTES,
+	PSP_A_STATS_TX_ERROR,
 
 	__PSP_A_STATS_MAX,
 	PSP_A_STATS_MAX = (__PSP_A_STATS_MAX - 1)

net/psp/psp_main.c

···
 		    !psd_ops->key_rotate ||
 		    !psd_ops->rx_spi_alloc ||
 		    !psd_ops->tx_key_add ||
-		    !psd_ops->tx_key_del))
+		    !psd_ops->tx_key_del ||
+		    !psd_ops->get_stats))
 		return ERR_PTR(-EINVAL);
 
 	psd = kzalloc(sizeof(*psd), GFP_KERNEL);

net/psp/psp_nl.c

···
 // SPDX-License-Identifier: GPL-2.0-only
 
+#include <linux/ethtool.h>
 #include <linux/skbuff.h>
 #include <linux/xarray.h>
 #include <net/genetlink.h>
···
 psp_nl_stats_fill(struct psp_dev *psd, struct sk_buff *rsp,
 		  const struct genl_info *info)
 {
+	unsigned int required_cnt = sizeof(struct psp_dev_stats) / sizeof(u64);
+	struct psp_dev_stats stats;
 	void *hdr;
+	int i;
+
+	memset(&stats, 0xff, sizeof(stats));
+	psd->ops->get_stats(psd, &stats);
+
+	for (i = 0; i < required_cnt; i++)
+		if (WARN_ON_ONCE(stats.required[i] == ETHTOOL_STAT_NOT_SET))
+			return -EOPNOTSUPP;
 
 	hdr = genlmsg_iput(rsp, info);
 	if (!hdr)
···
 	if (nla_put_u32(rsp, PSP_A_STATS_DEV_ID, psd->id) ||
 	    nla_put_uint(rsp, PSP_A_STATS_KEY_ROTATIONS,
 			 psd->stats.rotations) ||
-	    nla_put_uint(rsp, PSP_A_STATS_STALE_EVENTS, psd->stats.stales))
+	    nla_put_uint(rsp, PSP_A_STATS_STALE_EVENTS, psd->stats.stales) ||
+	    nla_put_uint(rsp, PSP_A_STATS_RX_PACKETS, stats.rx_packets) ||
+	    nla_put_uint(rsp, PSP_A_STATS_RX_BYTES, stats.rx_bytes) ||
+	    nla_put_uint(rsp, PSP_A_STATS_RX_AUTH_FAIL, stats.rx_auth_fail) ||
+	    nla_put_uint(rsp, PSP_A_STATS_RX_ERROR, stats.rx_error) ||
+	    nla_put_uint(rsp, PSP_A_STATS_RX_BAD, stats.rx_bad) ||
+	    nla_put_uint(rsp, PSP_A_STATS_TX_PACKETS, stats.tx_packets) ||
+	    nla_put_uint(rsp, PSP_A_STATS_TX_BYTES, stats.tx_bytes) ||
+	    nla_put_uint(rsp, PSP_A_STATS_TX_ERROR, stats.tx_error))
 		goto err_cancel_msg;
 
 	genlmsg_end(rsp, hdr);