net/sfc/base: improve API to get supported filter matches

The previous API had various problems, including the length of the
caller provided buffer not being specified, no means being available
to discover how big the buffer needs to be, and a lack of clarity of
what the resulting list contains.

To improve it:
- add the buffer length as a parameter
- if the provided buffer is too short, fail with ENOSPC and return
  the required length
- ensure that the list contents are valid and add comments describing it

It is safe to change this API as, unsurprisingly, it has no users.

Signed-off-by: Mark Spender <mspender@solarflare.com>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>

drivers/net/sfc/base/ef10_filter.c

@@ -868,13 +868,16 @@ ef10_filter_delete(
 
 static	__checkReturn	efx_rc_t
 efx_mcdi_get_parser_disp_info(
-	__in		efx_nic_t *enp,
+	__in				efx_nic_t *enp,
-	__out		uint32_t *list,
+	__out_ecount(buffer_length)	uint32_t *buffer,
-	__out		size_t *length)
+	__in				size_t buffer_length,
+	__out				size_t *list_lengthp)
 {
 	efx_mcdi_req_t req;
 	uint8_t payload[MAX(MC_CMD_GET_PARSER_DISP_INFO_IN_LEN,
 			    MC_CMD_GET_PARSER_DISP_INFO_OUT_LENMAX)];
+	size_t matches_count;
+	size_t list_size;
 	efx_rc_t rc;
 
 	(void) memset(payload, 0, sizeof (payload));
@@ -894,25 +897,41 @@ efx_mcdi_get_parser_disp_info(
 		goto fail1;
 	}
 
-	*length = MCDI_OUT_DWORD(req,
+	matches_count = MCDI_OUT_DWORD(req,
 	    GET_PARSER_DISP_INFO_OUT_NUM_SUPPORTED_MATCHES);
 
 	if (req.emr_out_length_used <
-	    MC_CMD_GET_PARSER_DISP_INFO_OUT_LEN(*length)) {
+	    MC_CMD_GET_PARSER_DISP_INFO_OUT_LEN(matches_count)) {
 		rc = EMSGSIZE;
 		goto fail2;
 	}
 
-	memcpy(list,
+	*list_lengthp = matches_count;
-	    MCDI_OUT2(req,
+
-	    uint32_t,
+	if (buffer_length < matches_count) {
-	    GET_PARSER_DISP_INFO_OUT_SUPPORTED_MATCHES),
+		rc = ENOSPC;
-	    (*length) * sizeof (uint32_t));
+		goto fail3;
+	}
+
+	/*
+	 * Check that the elements in the list in the MCDI response are the size
+	 * we expect, so we can just copy them directly. Any conversion of the
+	 * flags is handled by the caller.
+	 */
 	EFX_STATIC_ASSERT(sizeof (uint32_t) ==
 	    MC_CMD_GET_PARSER_DISP_INFO_OUT_SUPPORTED_MATCHES_LEN);
 
+	list_size = matches_count *
+		MC_CMD_GET_PARSER_DISP_INFO_OUT_SUPPORTED_MATCHES_LEN;
+	memcpy(buffer,
+	    MCDI_OUT2(req, uint32_t,
+		    GET_PARSER_DISP_INFO_OUT_SUPPORTED_MATCHES),
+	    list_size);
+
 	return (0);
 
+fail3:
+	EFSYS_PROBE(fail3);
 fail2:
 	EFSYS_PROBE(fail2);
 fail1:
@@ -923,14 +942,55 @@ efx_mcdi_get_parser_disp_info(
 
 	__checkReturn	efx_rc_t
 ef10_filter_supported_filters(
-	__in		efx_nic_t *enp,
+	__in				efx_nic_t *enp,
-	__out		uint32_t *list,
+	__out_ecount(buffer_length)	uint32_t *buffer,
-	__out		size_t *length)
+	__in				size_t buffer_length,
+	__out				size_t *list_lengthp)
 {
-	efx_rc_t rc;
 
-	if ((rc = efx_mcdi_get_parser_disp_info(enp, list, length)) != 0)
+	size_t mcdi_list_length;
+	size_t list_length;
+	uint32_t i;
+	efx_rc_t rc;
+	uint32_t all_filter_flags =
+	    (EFX_FILTER_MATCH_REM_HOST | EFX_FILTER_MATCH_LOC_HOST |
+	    EFX_FILTER_MATCH_REM_MAC | EFX_FILTER_MATCH_REM_PORT |
+	    EFX_FILTER_MATCH_LOC_MAC | EFX_FILTER_MATCH_LOC_PORT |
+	    EFX_FILTER_MATCH_ETHER_TYPE | EFX_FILTER_MATCH_INNER_VID |
+	    EFX_FILTER_MATCH_OUTER_VID | EFX_FILTER_MATCH_IP_PROTO |
+	    EFX_FILTER_MATCH_UNKNOWN_MCAST_DST |
+	    EFX_FILTER_MATCH_UNKNOWN_UCAST_DST);
+
+	rc = efx_mcdi_get_parser_disp_info(enp, buffer, buffer_length,
+					    &mcdi_list_length);
+	if (rc != 0) {
+		if (rc == ENOSPC) {
+			/* Pass through mcdi_list_length for the list length */
+			*list_lengthp = mcdi_list_length;
+		}
 		goto fail1;
+	}
+
+	/*
+	 * The static assertions in ef10_filter_init() ensure that the values of
+	 * the EFX_FILTER_MATCH flags match those used by MCDI, so they don't
+	 * need to be converted.
+	 *
+	 * In case support is added to MCDI for additional flags, remove any
+	 * matches from the list which include flags we don't support. The order
+	 * of the matches is preserved as they are ordered from highest to
+	 * lowest priority.
+	 */
+	EFSYS_ASSERT(mcdi_list_length <= buffer_length);
+	list_length = 0;
+	for (i = 0; i < mcdi_list_length; i++) {
+		if ((buffer[i] & ~all_filter_flags) == 0) {
+			buffer[list_length] = buffer[i];
+			list_length++;
+		}
+	}
+
+	*list_lengthp = list_length;
 
 	return (0);
 

drivers/net/sfc/base/ef10_impl.h

@@ -1043,9 +1043,10 @@ ef10_filter_delete(
 
 extern	__checkReturn	efx_rc_t
 ef10_filter_supported_filters(
-	__in		efx_nic_t *enp,
+	__in				efx_nic_t *enp,
-	__out		uint32_t *list,
+	__out_ecount(buffer_length)	uint32_t *buffer,
-	__out		size_t *length);
+	__in				size_t buffer_length,
+	__out				size_t *list_lengthp);
 
 extern	__checkReturn	efx_rc_t
 ef10_filter_reconfigure(

drivers/net/sfc/base/efx.h

@@ -2300,9 +2300,10 @@ efx_filter_restore(
 
 extern	__checkReturn	efx_rc_t
 efx_filter_supported_filters(
-	__in		efx_nic_t *enp,
+	__in				efx_nic_t *enp,
-	__out		uint32_t *list,
+	__out_ecount(buffer_length)	uint32_t *buffer,
-	__out		size_t *length);
+	__in				size_t buffer_length,
+	__out				size_t *list_lengthp);
 
 extern			void
 efx_filter_spec_init_rx(

drivers/net/sfc/base/efx_filter.c

@@ -61,9 +61,10 @@ siena_filter_delete(
 
 static	__checkReturn	efx_rc_t
 siena_filter_supported_filters(
-	__in		efx_nic_t *enp,
+	__in				efx_nic_t *enp,
-	__out		uint32_t *list,
+	__out_ecount(buffer_length)	uint32_t *buffer,
-	__out		size_t *length);
+	__in				size_t buffer_length,
+	__out				size_t *list_lengthp);
 
 #endif /* EFSYS_OPT_SIENA */
 
@@ -209,11 +210,22 @@ efx_filter_fini(
 	enp->en_mod_flags &= ~EFX_MOD_FILTER;
 }
 
+/*
+ * Query the possible combinations of match flags which can be filtered on.
+ * These are returned as a list, of which each 32 bit element is a bitmask
+ * formed of EFX_FILTER_MATCH flags.
+ *
+ * The combinations are ordered in priority from highest to lowest.
+ *
+ * If the provided buffer is too short to hold the list, the call with fail with
+ * ENOSPC and *list_lengthp will be set to the buffer length required.
+ */
 	__checkReturn	efx_rc_t
 efx_filter_supported_filters(
-	__in		efx_nic_t *enp,
+	__in				efx_nic_t *enp,
-	__out		uint32_t *list,
+	__out_ecount(buffer_length)	uint32_t *buffer,
-	__out		size_t *length)
+	__in				size_t buffer_length,
+	__out				size_t *list_lengthp)
 {
 	efx_rc_t rc;
 
@@ -222,11 +234,20 @@ efx_filter_supported_filters(
 	EFSYS_ASSERT3U(enp->en_mod_flags, &, EFX_MOD_FILTER);
 	EFSYS_ASSERT(enp->en_efop->efo_supported_filters != NULL);
 
-	if ((rc = enp->en_efop->efo_supported_filters(enp, list, length)) != 0)
+	if (buffer == NULL) {
+		rc = EINVAL;
 		goto fail1;
+	}
+
+	rc = enp->en_efop->efo_supported_filters(enp, buffer, buffer_length,
+						    list_lengthp);
+	if (rc != 0)
+		goto fail2;
 
 	return (0);
 
+fail2:
+	EFSYS_PROBE(fail2);
 fail1:
 	EFSYS_PROBE1(fail1, efx_rc_t, rc);
 
@@ -1346,23 +1367,20 @@ siena_filter_delete(
 	return (rc);
 }
 
-#define	MAX_SUPPORTED 4
+#define	SIENA_MAX_SUPPORTED_MATCHES 4
 
 static	__checkReturn	efx_rc_t
 siena_filter_supported_filters(
-	__in		efx_nic_t *enp,
+	__in				efx_nic_t *enp,
-	__out		uint32_t *list,
+	__out_ecount(buffer_length)	uint32_t *buffer,
-	__out		size_t *length)
+	__in				size_t buffer_length,
+	__out				size_t *list_lengthp)
 {
-	int index = 0;
+	uint32_t index = 0;
-	uint32_t rx_matches[MAX_SUPPORTED];
+	uint32_t rx_matches[SIENA_MAX_SUPPORTED_MATCHES];
+	size_t list_length;
 	efx_rc_t rc;
 
-	if (list == NULL) {
-		rc = EINVAL;
-		goto fail1;
-	}
-
 	rx_matches[index++] =
 	    EFX_FILTER_MATCH_ETHER_TYPE | EFX_FILTER_MATCH_IP_PROTO |
 	    EFX_FILTER_MATCH_LOC_HOST | EFX_FILTER_MATCH_LOC_PORT |
@@ -1379,14 +1397,22 @@ siena_filter_supported_filters(
 		rx_matches[index++] = EFX_FILTER_MATCH_LOC_MAC;
 	}
 
-	EFSYS_ASSERT3U(index, <=, MAX_SUPPORTED);
+	EFSYS_ASSERT3U(index, <=, SIENA_MAX_SUPPORTED_MATCHES);
+	list_length = index;
 
-	*length = index;
+	*list_lengthp = list_length;
-	memcpy(list, rx_matches, *length);
+
+	if (buffer_length < list_length) {
+		rc = ENOSPC;
+		goto fail1;
+	}
+
+	memcpy(buffer, rx_matches, list_length * sizeof (rx_matches[0]));
 
 	return (0);
 
 fail1:
+	EFSYS_PROBE1(fail1, efx_rc_t, rc);
 
 	return (rc);
 }

drivers/net/sfc/base/efx_impl.h

@@ -235,7 +235,8 @@ typedef struct efx_filter_ops_s {
 	efx_rc_t	(*efo_add)(efx_nic_t *, efx_filter_spec_t *,
 				   boolean_t may_replace);
 	efx_rc_t	(*efo_delete)(efx_nic_t *, efx_filter_spec_t *);
-	efx_rc_t	(*efo_supported_filters)(efx_nic_t *, uint32_t *, size_t *);
+	efx_rc_t	(*efo_supported_filters)(efx_nic_t *, uint32_t *,
+				   size_t, size_t *);
 	efx_rc_t	(*efo_reconfigure)(efx_nic_t *, uint8_t const *, boolean_t,
 				   boolean_t, boolean_t, boolean_t,
 				   uint8_t const *, uint32_t);