e1000e: 82579 potential system hang on stress when ME enabled

Previously, a workaround was added to address a hardware bug in the
PCIm2PCI arbiter where a write by the driver of the Transmit/Receive
Descriptor Tail register could happen concurrently with a write of any
MAC CSR register by the Manageability Engine (ME) which could cause the
Tail register to have an incorrect value.  The arbiter is supposed to
prevent the concurrent writes but there is a bug that can cause the Host
(driver) access to be acknowledged later than it should.
After further investigation, it was discovered that a driver write access
of any MAC CSR register after being idle for some time can be lost when
ME is accessing a MAC CSR register.  When this happens, no further target
access is claimed by the MAC which could hang the system.
The workaround to check bit 24 in the FWSM register (set only when ME is
accessing a MAC CSR register) and delay for a limited amount of time until
it is cleared is now done for all driver writes of MAC CSR registers on
82579 with ME enabled.  In the rare case when the driver is writing the
Tail register and ME is accessing any MAC CSR register for a duration
longer than the maximum delay, write the register and verify it has the
correct value before continuing, otherwise reset the device.

This patch also moves some pre-existing macros from the hardware-specific
header file to the more appropriate generic driver header file.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000e/e1000.h

@@ -735,9 +735,46 @@ static inline u32 __er32(struct e1000_hw *hw, unsigned long reg)
 	return readl(hw->hw_addr + reg);
 }
 
+#define er32(reg)	__er32(hw, E1000_##reg)
+
+/**
+ * __ew32_prepare - prepare to write to MAC CSR register on certain parts
+ * @hw: pointer to the HW structure
+ *
+ * When updating the MAC CSR registers, the Manageability Engine (ME) could
+ * be accessing the registers at the same time.  Normally, this is handled in
+ * h/w by an arbiter but on some parts there is a bug that acknowledges Host
+ * accesses later than it should which could result in the register to have
+ * an incorrect value.  Workaround this by checking the FWSM register which
+ * has bit 24 set while ME is accessing MAC CSR registers, wait if it is set
+ * and try again a number of times.
+ **/
+static inline s32 __ew32_prepare(struct e1000_hw *hw)
+{
+	s32 i = E1000_ICH_FWSM_PCIM2PCI_COUNT;
+
+	while ((er32(FWSM) & E1000_ICH_FWSM_PCIM2PCI) && --i)
+		udelay(50);
+
+	return i;
+}
+
 static inline void __ew32(struct e1000_hw *hw, unsigned long reg, u32 val)
 {
+	if (hw->adapter->flags2 & FLAG2_PCIM2PCI_ARBITER_WA)
+		__ew32_prepare(hw);
+
 	writel(val, hw->hw_addr + reg);
 }
 
+#define ew32(reg, val)	__ew32(hw, E1000_##reg, (val))
+
+#define e1e_flush()	er32(STATUS)
+
+#define E1000_WRITE_REG_ARRAY(a, reg, offset, value) \
+	(__ew32((a), (reg + ((offset) << 2)), (value)))
+
+#define E1000_READ_REG_ARRAY(a, reg, offset) \
+	(readl((a)->hw_addr + reg + ((offset) << 2)))
+
 #endif /* _E1000_H_ */

drivers/net/ethernet/intel/e1000e/hw.h

@@ -36,16 +36,6 @@ struct e1000_adapter;
 
 #include "defines.h"
 
-#define er32(reg)	__er32(hw, E1000_##reg)
-#define ew32(reg,val)	__ew32(hw, E1000_##reg, (val))
-#define e1e_flush()	er32(STATUS)
-
-#define E1000_WRITE_REG_ARRAY(a, reg, offset, value) \
-	(writel((value), ((a)->hw_addr + reg + ((offset) << 2))))
-
-#define E1000_READ_REG_ARRAY(a, reg, offset) \
-	(readl((a)->hw_addr + reg + ((offset) << 2)))
-
 enum e1e_registers {
 	E1000_CTRL     = 0x00000, /* Device Control - RW */
 	E1000_STATUS   = 0x00008, /* Device Status - RO */

drivers/net/ethernet/intel/e1000e/netdev.c

@@ -538,43 +538,15 @@ static void e1000_rx_checksum(struct e1000_adapter *adapter, u32 status_err,
 	adapter->hw_csum_good++;
 }
 
-/**
- * e1000e_update_tail_wa - helper function for e1000e_update_[rt]dt_wa()
- * @hw: pointer to the HW structure
- * @tail: address of tail descriptor register
- * @i: value to write to tail descriptor register
- *
- * When updating the tail register, the ME could be accessing Host CSR
- * registers at the same time.  Normally, this is handled in h/w by an
- * arbiter but on some parts there is a bug that acknowledges Host accesses
- * later than it should which could result in the descriptor register to
- * have an incorrect value.  Workaround this by checking the FWSM register
- * which has bit 24 set while ME is accessing Host CSR registers, wait
- * if it is set and try again a number of times.
- **/
-static inline s32 e1000e_update_tail_wa(struct e1000_hw *hw, void __iomem *tail,
-					unsigned int i)
-{
-	unsigned int j = 0;
-
-	while ((j++ < E1000_ICH_FWSM_PCIM2PCI_COUNT) &&
-	       (er32(FWSM) & E1000_ICH_FWSM_PCIM2PCI))
-		udelay(50);
-
-	writel(i, tail);
-
-	if ((j == E1000_ICH_FWSM_PCIM2PCI_COUNT) && (i != readl(tail)))
-		return E1000_ERR_SWFW_SYNC;
-
-	return 0;
-}
-
 static void e1000e_update_rdt_wa(struct e1000_ring *rx_ring, unsigned int i)
 {
 	struct e1000_adapter *adapter = rx_ring->adapter;
 	struct e1000_hw *hw = &adapter->hw;
+	s32 ret_val = __ew32_prepare(hw);
 
-	if (e1000e_update_tail_wa(hw, rx_ring->tail, i)) {
+	writel(i, rx_ring->tail);
+
+	if (unlikely(!ret_val && (i != readl(rx_ring->tail)))) {
 		u32 rctl = er32(RCTL);
 		ew32(RCTL, rctl & ~E1000_RCTL_EN);
 		e_err("ME firmware caused invalid RDT - resetting\n");
@@ -586,8 +558,11 @@ static void e1000e_update_tdt_wa(struct e1000_ring *tx_ring, unsigned int i)
 {
 	struct e1000_adapter *adapter = tx_ring->adapter;
 	struct e1000_hw *hw = &adapter->hw;
+	s32 ret_val = __ew32_prepare(hw);
 
-	if (e1000e_update_tail_wa(hw, tx_ring->tail, i)) {
+	writel(i, tx_ring->tail);
+
+	if (unlikely(!ret_val && (i != readl(tx_ring->tail)))) {
 		u32 tctl = er32(TCTL);
 		ew32(TCTL, tctl & ~E1000_TCTL_EN);
 		e_err("ME firmware caused invalid TDT - resetting\n");
@@ -1646,7 +1621,10 @@ static void e1000_clean_rx_ring(struct e1000_ring *rx_ring)
 	adapter->flags2 &= ~FLAG2_IS_DISCARDING;
 
 	writel(0, rx_ring->head);
-	writel(0, rx_ring->tail);
+	if (rx_ring->adapter->flags2 & FLAG2_PCIM2PCI_ARBITER_WA)
+		e1000e_update_rdt_wa(rx_ring, 0);
+	else
+		writel(0, rx_ring->tail);
 }
 
 static void e1000e_downshift_workaround(struct work_struct *work)
@@ -2319,7 +2297,10 @@ static void e1000_clean_tx_ring(struct e1000_ring *tx_ring)
 	tx_ring->next_to_clean = 0;
 
 	writel(0, tx_ring->head);
-	writel(0, tx_ring->tail);
+	if (tx_ring->adapter->flags2 & FLAG2_PCIM2PCI_ARBITER_WA)
+		e1000e_update_tdt_wa(tx_ring, 0);
+	else
+		writel(0, tx_ring->tail);
 }
 
 /**