[dpdk-dev] [PATCH 40/80] net/sfc/base: use MAC stats DMA buffer size when decoding

[Andrew Rybchenko]

From: Andy Moreton <amoreton at solarflare.com>

On Medford2 and later the MAC stats buffer has been enlarged.
Use the MAC stats DMA buffer size to ensure that the stats END
generation count is read from the correct location, and that
over-reading of the DMA buffer is prevented.

Signed-off-by: Andy Moreton <amoreton at solarflare.com>
Signed-off-by: Andrew Rybchenko <arybchenko at solarflare.com>
---
 drivers/net/sfc/base/ef10_mac.c  | 50 ++++++++++++++++++++++++++++++++++------
 drivers/net/sfc/base/siena_mac.c | 29 +++++++++++++++++++----
 2 files changed, 67 insertions(+), 12 deletions(-)

diff --git a/drivers/net/sfc/base/ef10_mac.c b/drivers/net/sfc/base/ef10_mac.c
index ed778f7..b1534a8 100644
--- a/drivers/net/sfc/base/ef10_mac.c
+++ b/drivers/net/sfc/base/ef10_mac.c
@@ -552,16 +552,45 @@ ef10_mac_stats_update(
 	__inout_ecount(EFX_MAC_NSTATS)	efsys_stat_t *stat,
 	__inout_opt			uint32_t *generationp)
 {
-	efx_qword_t value;
+	const efx_nic_cfg_t *encp = &enp->en_nic_cfg;
 	efx_qword_t generation_start;
 	efx_qword_t generation_end;
+	efx_qword_t value;
+	efx_rc_t rc;
 
-	_NOTE(ARGUNUSED(enp))
+	/*
+	 * The MAC_STATS contain start and end generation counters used to
+	 * detect when the DMA buffer has been updated during stats decode.
+	 * All stats counters are 64bit unsigned values.
+	 *
+	 * Siena-compatible MAC stats contain MC_CMD_MAC_NSTATS 64bit counters.
+	 * The generation end counter is at index MC_CMD_MAC_GENERATION_END
+	 * (same as MC_CMD_MAC_NSTATS-1).
+	 *
+	 * Medford2 and later use a larger DMA buffer: MAC_STATS_NUM_STATS from
+	 * MC_CMD_GET_CAPABILITIES_V4_OUT reports the number of 64bit counters.
+	 *
+	 * Firmware writes the generation end counter as the last counter in the
+	 * DMA buffer. Do not use MC_CMD_MAC_GENERATION_END, as that is only
+	 * correct for legacy Siena-compatible MAC stats.
+	 */
+
+	if (encp->enc_mac_stats_nstats < MC_CMD_MAC_NSTATS) {
+		/* MAC stats count too small for legacy MAC stats */
+		rc = ENOSPC;
+		goto fail1;
+	}
+	if (EFSYS_MEM_SIZE(esmp) <
+	    (encp->enc_mac_stats_nstats * sizeof (efx_qword_t))) {
+		/* DMA buffer too small */
+		rc = ENOSPC;
+		goto fail2;
+	}
 
 	/* Read END first so we don't race with the MC */
-	EFSYS_DMA_SYNC_FOR_KERNEL(esmp, 0, EFX_MAC_STATS_SIZE);
-	EF10_MAC_STAT_READ(esmp, MC_CMD_MAC_GENERATION_END,
-			    &generation_end);
+	EFSYS_DMA_SYNC_FOR_KERNEL(esmp, 0, EFSYS_MEM_SIZE(esmp));
+	EF10_MAC_STAT_READ(esmp, (encp->enc_mac_stats_nstats - 1),
+	    &generation_end);
 	EFSYS_MEM_READ_BARRIER();
 
 	/* TX */
@@ -851,8 +880,8 @@ ef10_mac_stats_update(
 	EF10_MAC_STAT_READ(esmp, MC_CMD_MAC_VADAPTER_TX_OVERFLOW, &value);
 	EFSYS_STAT_SET_QWORD(&(stat[EFX_MAC_VADAPTER_TX_OVERFLOW]), &value);
 
-
-	EFSYS_DMA_SYNC_FOR_KERNEL(esmp, 0, EFX_MAC_STATS_SIZE);
+	/* Read START generation counter */
+	EFSYS_DMA_SYNC_FOR_KERNEL(esmp, 0, EFSYS_MEM_SIZE(esmp));
 	EFSYS_MEM_READ_BARRIER();
 	EF10_MAC_STAT_READ(esmp, MC_CMD_MAC_GENERATION_START,
 			    &generation_start);
@@ -867,6 +896,13 @@ ef10_mac_stats_update(
 		*generationp = EFX_QWORD_FIELD(generation_start, EFX_DWORD_0);
 
 	return (0);
+
+fail2:
+	EFSYS_PROBE(fail2);
+fail1:
+	EFSYS_PROBE1(fail1, efx_rc_t, rc);
+
+	return (rc);
 }
 
 #endif	/* EFSYS_OPT_MAC_STATS */
diff --git a/drivers/net/sfc/base/siena_mac.c b/drivers/net/sfc/base/siena_mac.c
index 904e03e..f395355 100644
--- a/drivers/net/sfc/base/siena_mac.c
+++ b/drivers/net/sfc/base/siena_mac.c
@@ -245,16 +245,28 @@ siena_mac_stats_update(
 	__inout_ecount(EFX_MAC_NSTATS)	efsys_stat_t *stat,
 	__inout_opt			uint32_t *generationp)
 {
-	efx_qword_t value;
+	const efx_nic_cfg_t *encp = &enp->en_nic_cfg;
 	efx_qword_t generation_start;
 	efx_qword_t generation_end;
+	efx_qword_t value;
+	efx_rc_t rc;
 
-	_NOTE(ARGUNUSED(enp))
+	if (encp->enc_mac_stats_nstats < MC_CMD_MAC_NSTATS) {
+		/* MAC stats count too small */
+		rc = ENOSPC;
+		goto fail1;
+	}
+	if (EFSYS_MEM_SIZE(esmp) <
+	    (encp->enc_mac_stats_nstats * sizeof (efx_qword_t))) {
+		/* DMA buffer too small */
+		rc = ENOSPC;
+		goto fail2;
+	}
 
 	/* Read END first so we don't race with the MC */
-	EFSYS_DMA_SYNC_FOR_KERNEL(esmp, 0, EFX_MAC_STATS_SIZE);
-	SIENA_MAC_STAT_READ(esmp, MC_CMD_MAC_GENERATION_END,
-			    &generation_end);
+	EFSYS_DMA_SYNC_FOR_KERNEL(esmp, 0, EFSYS_MEM_SIZE(esmp));
+	SIENA_MAC_STAT_READ(esmp, (encp->enc_mac_stats_nstats - 1),
+	    &generation_end);
 	EFSYS_MEM_READ_BARRIER();
 
 	/* TX */
@@ -437,6 +449,13 @@ siena_mac_stats_update(
 		*generationp = EFX_QWORD_FIELD(generation_start, EFX_DWORD_0);
 
 	return (0);
+
+fail2:
+	EFSYS_PROBE(fail2);
+fail1:
+	EFSYS_PROBE1(fail1, efx_rc_t, rc);
+
+	return (rc);
 }
 
 #endif	/* EFSYS_OPT_MAC_STATS */
-- 
2.7.4