ixgbe: Avoid Tx hang by not allowing more than the number of VFs supported.

When DCB is enabled, add checks to ensure creation of number of VF's is
valid based on the traffic classes configured by the device.
Signed-off-by: Usha Ketineni <usha.k.ketineni@intel.com>
Tested-by: Ronald Bynoe <ronald.j.bynoe@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -298,6 +298,7 @@ static int ixgbe_pci_sriov_enable(struct pci_dev *dev, int num_vfs)
 #ifdef CONFIG_PCI_IOV
 	struct ixgbe_adapter *adapter = pci_get_drvdata(dev);
 	int err = 0;
+	u8 num_tc;
 	int i;
 	int pre_existing_vfs = pci_num_vf(dev);
 
@@ -310,16 +311,35 @@ static int ixgbe_pci_sriov_enable(struct pci_dev *dev, int num_vfs)
 		return err;
 
 	/* While the SR-IOV capability structure reports total VFs to be 64,
-	 * we have to limit the actual number allocated based on two factors.
+	 * we limit the actual number allocated as below based on two factors.
+	 *    Num_TCs	MAX_VFs
+	 *	1	  63
+	 *	<=4	  31
+	 *	>4	  15
 	 * First, we reserve some transmit/receive resources for the PF.
 	 * Second, VMDQ also uses the same pools that SR-IOV does. We need to
 	 * account for this, so that we don't accidentally allocate more VFs
 	 * than we have available pools. The PCI bus driver already checks for
 	 * other values out of range.
 	 */
-	if ((num_vfs + adapter->num_rx_pools) > IXGBE_MAX_VF_FUNCTIONS)
-		return -EPERM;
+	num_tc = netdev_get_num_tc(adapter->netdev);
 
+	if (num_tc > 4) {
+		if ((num_vfs + adapter->num_rx_pools) > IXGBE_MAX_VFS_8TC) {
+			e_dev_err("Currently the device is configured with %d TCs, Creating more than %d VFs is not allowed\n", num_tc, IXGBE_MAX_VFS_8TC);
+			return -EPERM;
+		}
+	} else if ((num_tc > 1) && (num_tc <= 4)) {
+		if ((num_vfs + adapter->num_rx_pools) > IXGBE_MAX_VFS_4TC) {
+			e_dev_err("Currently the device is configured with %d TCs, Creating more than %d VFs is not allowed\n", num_tc, IXGBE_MAX_VFS_4TC);
+			return -EPERM;
+		}
+	} else {
+		if ((num_vfs + adapter->num_rx_pools) > IXGBE_MAX_VFS_1TC) {
+			e_dev_err("Currently the device is configured with %d TCs, Creating more than %d VFs is not allowed\n", num_tc, IXGBE_MAX_VFS_1TC);
+			return -EPERM;
+		}
+	}
 	adapter->num_vfs = num_vfs;
 
 	err = __ixgbe_enable_sriov(adapter);

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

@@ -33,6 +33,9 @@
  *  63 (IXGBE_MAX_VF_FUNCTIONS - 1)
  */
 #define IXGBE_MAX_VFS_DRV_LIMIT  (IXGBE_MAX_VF_FUNCTIONS - 1)
+#define IXGBE_MAX_VFS_1TC		IXGBE_MAX_VF_FUNCTIONS
+#define IXGBE_MAX_VFS_4TC		32
+#define IXGBE_MAX_VFS_8TC		16
 
 #ifdef CONFIG_PCI_IOV
 void ixgbe_restore_vf_multicasts(struct ixgbe_adapter *adapter);