ixgbevf: Fix VF Stats accounting after reset

The counters in the 82599 Virtual Function are not clear on read. They
accumulate to the maximum value and then roll over. They are also not
cleared when the VF executes a soft reset, so it is possible they are
non-zero when the driver loads and starts. This has all been accounted
for in the code that keeps the stats up to date but there is one case
that is not. When the PF driver is reset the counters in the VF are
all reset to zero. This adds an additional accounting overhead into
the VF driver when the PF is reset under its feet. This patch adds
additional counters that are used by the VF driver to accumulate and
save stats after a PF reset has been detected. Prior to this patch
displaying the stats in the VF after the PF has reset would show
bogus data.

Signed-off-by: Greg Rose <[e-mail]>
Signed-off-by: Jeff Kirsher <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ixgbevf/ethtool.c

···
 	int sizeof_stat;
 	int stat_offset;
 	int base_stat_offset;
+	int saved_reset_offset;
 };
 
-#define IXGBEVF_STAT(m, b)  sizeof(((struct ixgbevf_adapter *)0)->m), \
-			    offsetof(struct ixgbevf_adapter, m),      \
-			    offsetof(struct ixgbevf_adapter, b)
+#define IXGBEVF_STAT(m, b, r)  sizeof(((struct ixgbevf_adapter *)0)->m), \
+			    offsetof(struct ixgbevf_adapter, m),         \
+			    offsetof(struct ixgbevf_adapter, b),         \
+			    offsetof(struct ixgbevf_adapter, r)
 static struct ixgbe_stats ixgbe_gstrings_stats[] = {
-	{"rx_packets", IXGBEVF_STAT(stats.vfgprc, stats.base_vfgprc)},
-	{"tx_packets", IXGBEVF_STAT(stats.vfgptc, stats.base_vfgptc)},
-	{"rx_bytes", IXGBEVF_STAT(stats.vfgorc, stats.base_vfgorc)},
-	{"tx_bytes", IXGBEVF_STAT(stats.vfgotc, stats.base_vfgotc)},
-	{"tx_busy", IXGBEVF_STAT(tx_busy, zero_base)},
-	{"multicast", IXGBEVF_STAT(stats.vfmprc, stats.base_vfmprc)},
-	{"rx_csum_offload_good", IXGBEVF_STAT(hw_csum_rx_good, zero_base)},
-	{"rx_csum_offload_errors", IXGBEVF_STAT(hw_csum_rx_error, zero_base)},
-	{"tx_csum_offload_ctxt", IXGBEVF_STAT(hw_csum_tx_good, zero_base)},
-	{"rx_header_split", IXGBEVF_STAT(rx_hdr_split, zero_base)},
+	{"rx_packets", IXGBEVF_STAT(stats.vfgprc, stats.base_vfgprc,
+				    stats.saved_reset_vfgprc)},
+	{"tx_packets", IXGBEVF_STAT(stats.vfgptc, stats.base_vfgptc,
+				    stats.saved_reset_vfgptc)},
+	{"rx_bytes", IXGBEVF_STAT(stats.vfgorc, stats.base_vfgorc,
+				  stats.saved_reset_vfgorc)},
+	{"tx_bytes", IXGBEVF_STAT(stats.vfgotc, stats.base_vfgotc,
+				  stats.saved_reset_vfgotc)},
+	{"tx_busy", IXGBEVF_STAT(tx_busy, zero_base, zero_base)},
+	{"multicast", IXGBEVF_STAT(stats.vfmprc, stats.base_vfmprc,
+				   stats.saved_reset_vfmprc)},
+	{"rx_csum_offload_good", IXGBEVF_STAT(hw_csum_rx_good, zero_base,
+					      zero_base)},
+	{"rx_csum_offload_errors", IXGBEVF_STAT(hw_csum_rx_error, zero_base,
+						zero_base)},
+	{"tx_csum_offload_ctxt", IXGBEVF_STAT(hw_csum_tx_good, zero_base,
+					      zero_base)},
+	{"rx_header_split", IXGBEVF_STAT(rx_hdr_split, zero_base, zero_base)},
 };
 
 #define IXGBE_QUEUE_STATS_LEN 0
···
 			ixgbe_gstrings_stats[i].stat_offset;
 		char *b = (char *)adapter +
 			ixgbe_gstrings_stats[i].base_stat_offset;
+		char *r = (char *)adapter +
+			ixgbe_gstrings_stats[i].saved_reset_offset;
 		data[i] = ((ixgbe_gstrings_stats[i].sizeof_stat ==
 			    sizeof(u64)) ? *(u64 *)p : *(u32 *)p) -
 			  ((ixgbe_gstrings_stats[i].sizeof_stat ==
-			    sizeof(u64)) ? *(u64 *)b : *(u32 *)b);
+			    sizeof(u64)) ? *(u64 *)b : *(u32 *)b) +
+			  ((ixgbe_gstrings_stats[i].sizeof_stat ==
+			    sizeof(u64)) ? *(u64 *)r : *(u32 *)r);
 	}
 }
 

drivers/net/ixgbevf/ixgbevf_main.c

···
 				(adapter->rx_ring[rxr].count - 1));
 }
 
+static void ixgbevf_save_reset_stats(struct ixgbevf_adapter *adapter)
+{
+	/* Only save pre-reset stats if there are some */
+	if (adapter->stats.vfgprc || adapter->stats.vfgptc) {
+		adapter->stats.saved_reset_vfgprc += adapter->stats.vfgprc -
+			adapter->stats.base_vfgprc;
+		adapter->stats.saved_reset_vfgptc += adapter->stats.vfgptc -
+			adapter->stats.base_vfgptc;
+		adapter->stats.saved_reset_vfgorc += adapter->stats.vfgorc -
+			adapter->stats.base_vfgorc;
+		adapter->stats.saved_reset_vfgotc += adapter->stats.vfgotc -
+			adapter->stats.base_vfgotc;
+		adapter->stats.saved_reset_vfmprc += adapter->stats.vfmprc -
+			adapter->stats.base_vfmprc;
+	}
+}
+
+static void ixgbevf_init_last_counter_stats(struct ixgbevf_adapter *adapter)
+{
+	struct ixgbe_hw *hw = &adapter->hw;
+
+	adapter->stats.last_vfgprc = IXGBE_READ_REG(hw, IXGBE_VFGPRC);
+	adapter->stats.last_vfgorc = IXGBE_READ_REG(hw, IXGBE_VFGORC_LSB);
+	adapter->stats.last_vfgorc |=
+		(((u64)(IXGBE_READ_REG(hw, IXGBE_VFGORC_MSB))) << 32);
+	adapter->stats.last_vfgptc = IXGBE_READ_REG(hw, IXGBE_VFGPTC);
+	adapter->stats.last_vfgotc = IXGBE_READ_REG(hw, IXGBE_VFGOTC_LSB);
+	adapter->stats.last_vfgotc |=
+		(((u64)(IXGBE_READ_REG(hw, IXGBE_VFGOTC_MSB))) << 32);
+	adapter->stats.last_vfmprc = IXGBE_READ_REG(hw, IXGBE_VFMPRC);
+
+	adapter->stats.base_vfgprc = adapter->stats.last_vfgprc;
+	adapter->stats.base_vfgorc = adapter->stats.last_vfgorc;
+	adapter->stats.base_vfgptc = adapter->stats.last_vfgptc;
+	adapter->stats.base_vfgotc = adapter->stats.last_vfgotc;
+	adapter->stats.base_vfmprc = adapter->stats.last_vfmprc;
+}
+
 static int ixgbevf_up_complete(struct ixgbevf_adapter *adapter)
 {
 	struct net_device *netdev = adapter->netdev;
···
 
 	/* enable transmits */
 	netif_tx_start_all_queues(netdev);
+
+	ixgbevf_save_reset_stats(adapter);
+	ixgbevf_init_last_counter_stats(adapter);
 
 	/* bring the link up in the watchdog, this could race with our first
 	 * link up interrupt but shouldn't be a problem */
···
 	return err;
 }
 
-static void ixgbevf_init_last_counter_stats(struct ixgbevf_adapter *adapter)
-{
-	struct ixgbe_hw *hw = &adapter->hw;
-
-	adapter->stats.last_vfgprc = IXGBE_READ_REG(hw, IXGBE_VFGPRC);
-	adapter->stats.last_vfgorc = IXGBE_READ_REG(hw, IXGBE_VFGORC_LSB);
-	adapter->stats.last_vfgorc |=
-		(((u64)(IXGBE_READ_REG(hw, IXGBE_VFGORC_MSB))) << 32);
-	adapter->stats.last_vfgptc = IXGBE_READ_REG(hw, IXGBE_VFGPTC);
-	adapter->stats.last_vfgotc = IXGBE_READ_REG(hw, IXGBE_VFGOTC_LSB);
-	adapter->stats.last_vfgotc |=
-		(((u64)(IXGBE_READ_REG(hw, IXGBE_VFGOTC_MSB))) << 32);
-	adapter->stats.last_vfmprc = IXGBE_READ_REG(hw, IXGBE_VFMPRC);
-
-	adapter->stats.base_vfgprc = adapter->stats.last_vfgprc;
-	adapter->stats.base_vfgorc = adapter->stats.last_vfgorc;
-	adapter->stats.base_vfgptc = adapter->stats.last_vfgptc;
-	adapter->stats.base_vfgotc = adapter->stats.last_vfgotc;
-	adapter->stats.base_vfmprc = adapter->stats.last_vfmprc;
-}
-
 #define UPDATE_VF_COUNTER_32bit(reg, last_counter, counter)	\
 	{							\
 		u32 current_counter = IXGBE_READ_REG(hw, reg);	\
···
 		}
 	}
 
-pf_has_reset:
 	ixgbevf_update_stats(adapter);
 
+pf_has_reset:
 	/* Force detection of hung controller every watchdog period */
 	adapter->detect_tx_hung = true;
 
···
 	/* setup the private structure */
 	err = ixgbevf_sw_init(adapter);
 
-	ixgbevf_init_last_counter_stats(adapter);
-
 #ifdef MAX_SKB_FRAGS
 	netdev->features = NETIF_F_SG |
 			   NETIF_F_IP_CSUM |
···
 		goto err_register;
 
 	adapter->netdev_registered = true;
+
+	ixgbevf_init_last_counter_stats(adapter);
 
 	/* print the MAC address */
 	hw_dbg(hw, "%2.2x:%2.2x:%2.2x:%2.2x:%2.2x:%2.2x\n",

drivers/net/ixgbevf/vf.h

···
 	u64 vfgorc;
 	u64 vfgotc;
 	u64 vfmprc;
+
+	u64 saved_reset_vfgprc;
+	u64 saved_reset_vfgptc;
+	u64 saved_reset_vfgorc;
+	u64 saved_reset_vfgotc;
+	u64 saved_reset_vfmprc;
 };
 
 struct ixgbevf_info {