ixgbe: Check register reads for adapter removal

Check all register reads for adapter removal by checking the status
register after any register read that returns 0xFFFFFFFF. Since the
status register will never return 0xFFFFFFFF unless the adapter is
removed, such a value from a status register read confirms the
removal.
Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/ixgbe/ixgbe.h

@@ -747,6 +747,7 @@ struct ixgbe_adapter {
 #ifdef IXGBE_FCOE
 	struct ixgbe_fcoe fcoe;
 #endif /* IXGBE_FCOE */
+	u8 __iomem *io_addr; /* Mainly for iounmap use */
 	u32 wol;
 
 	u16 bd_number;

drivers/net/ethernet/intel/ixgbe/ixgbe_common.h

@@ -124,6 +124,15 @@ s32 ixgbe_reset_pipeline_82599(struct ixgbe_hw *hw);
 s32 ixgbe_get_thermal_sensor_data_generic(struct ixgbe_hw *hw);
 s32 ixgbe_init_thermal_sensor_thresh_generic(struct ixgbe_hw *hw);
 
+#define IXGBE_FAILED_READ_REG 0xffffffffU
+
+static inline bool ixgbe_removed(void __iomem *addr)
+{
+	return unlikely(!addr);
+}
+
+void ixgbe_check_remove(struct ixgbe_hw *hw, u32 reg);
+
 static inline void ixgbe_write_reg(struct ixgbe_hw *hw, u32 reg, u32 value)
 {
 	writel(value, hw->hw_addr + reg);
@@ -147,7 +156,15 @@ static inline void ixgbe_write_reg64(struct ixgbe_hw *hw, u32 reg, u64 value)
 
 static inline u32 ixgbe_read_reg(struct ixgbe_hw *hw, u32 reg)
 {
-	return readl(hw->hw_addr + reg);
+	u8 __iomem *reg_addr = ACCESS_ONCE(hw->hw_addr);
+	u32 value;
+
+	if (ixgbe_removed(reg_addr))
+		return IXGBE_FAILED_READ_REG;
+	value = readl(reg_addr + reg);
+	if (unlikely(value == IXGBE_FAILED_READ_REG))
+		ixgbe_check_remove(hw, reg);
+	return value;
 }
 #define IXGBE_READ_REG(a, reg) ixgbe_read_reg((a), (reg))
 

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -283,6 +283,35 @@ static void ixgbe_service_event_schedule(struct ixgbe_adapter *adapter)
 		schedule_work(&adapter->service_task);
 }
 
+static void ixgbe_remove_adapter(struct ixgbe_hw *hw)
+{
+	struct ixgbe_adapter *adapter = hw->back;
+
+	if (!hw->hw_addr)
+		return;
+	hw->hw_addr = NULL;
+	e_dev_err("Adapter removed\n");
+}
+
+void ixgbe_check_remove(struct ixgbe_hw *hw, u32 reg)
+{
+	u32 value;
+
+	/* The following check not only optimizes a bit by not
+	 * performing a read on the status register when the
+	 * register just read was a status register read that
+	 * returned IXGBE_FAILED_READ_REG. It also blocks any
+	 * potential recursion.
+	 */
+	if (reg == IXGBE_STATUS) {
+		ixgbe_remove_adapter(hw);
+		return;
+	}
+	value = ixgbe_read_reg(hw, IXGBE_STATUS);
+	if (value == IXGBE_FAILED_READ_REG)
+		ixgbe_remove_adapter(hw);
+}
+
 static void ixgbe_service_event_complete(struct ixgbe_adapter *adapter)
 {
 	BUG_ON(!test_bit(__IXGBE_SERVICE_SCHED, &adapter->state));
@@ -2970,7 +2999,7 @@ void ixgbe_configure_tx_ring(struct ixgbe_adapter *adapter,
 			ring->count * sizeof(union ixgbe_adv_tx_desc));
 	IXGBE_WRITE_REG(hw, IXGBE_TDH(reg_idx), 0);
 	IXGBE_WRITE_REG(hw, IXGBE_TDT(reg_idx), 0);
-	ring->tail = hw->hw_addr + IXGBE_TDT(reg_idx);
+	ring->tail = adapter->io_addr + IXGBE_TDT(reg_idx);
 
 	/*
 	 * set WTHRESH to encourage burst writeback, it should not be set
@@ -3373,7 +3402,7 @@ void ixgbe_configure_rx_ring(struct ixgbe_adapter *adapter,
 			ring->count * sizeof(union ixgbe_adv_rx_desc));
 	IXGBE_WRITE_REG(hw, IXGBE_RDH(reg_idx), 0);
 	IXGBE_WRITE_REG(hw, IXGBE_RDT(reg_idx), 0);
-	ring->tail = hw->hw_addr + IXGBE_RDT(reg_idx);
+	ring->tail = adapter->io_addr + IXGBE_RDT(reg_idx);
 
 	ixgbe_configure_srrctl(adapter, ring);
 	ixgbe_configure_rscctl(adapter, ring);
@@ -7880,6 +7909,7 @@ static int ixgbe_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	hw->hw_addr = ioremap(pci_resource_start(pdev, 0),
 			      pci_resource_len(pdev, 0));
+	adapter->io_addr = hw->hw_addr;
 	if (!hw->hw_addr) {
 		err = -EIO;
 		goto err_ioremap;
@@ -8188,7 +8218,7 @@ static int ixgbe_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 err_sw_init:
 	ixgbe_disable_sriov(adapter);
 	adapter->flags2 &= ~IXGBE_FLAG2_SEARCH_FOR_SFP;
-	iounmap(hw->hw_addr);
+	iounmap(adapter->io_addr);
 err_ioremap:
 	free_netdev(netdev);
 err_alloc_etherdev:
@@ -8255,7 +8285,7 @@ static void ixgbe_remove(struct pci_dev *pdev)
 	kfree(adapter->ixgbe_ieee_ets);
 
 #endif
-	iounmap(adapter->hw.hw_addr);
+	iounmap(adapter->io_addr);
 	pci_release_selected_regions(pdev, pci_select_bars(pdev,
 				     IORESOURCE_MEM));