net/ixgbevf: add full link status check option

To get the VF's link status by calling 'rte_eth_link_get_nowait()', the
VF not only check PF's physical link status, but also check the mailbox
running status. And mailbox checking will generate mailbox interrupt in
PF, it will be worse if many VFs are running in the system, the PF will
have to handle many interrrupts.

Normally, checking the PF's physical link status is enough for nowait.
For different scenarios, adding an 'pflink_fullchk' option to control
whether to check the link fully or not.

Fixes: 91546fb62e ("net/ixgbevf: fix link state")
Cc: stable@dpdk.org

Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Acked-by: Scott Daniels <daniels@research.att.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>

doc/guides/nics/ixgbe.rst

@@ -82,6 +82,31 @@ To guarantee the constraint, capabilities in dev_conf.rxmode.offloads will be ch
 
 fdir_conf->mode will also be checked.
 
+VF Runtime Options
+^^^^^^^^^^^^^^^^^^
+
+The following ``devargs`` options can be enabled at runtime. They must
+be passed as part of EAL arguments. For example,
+
+.. code-block:: console
+
+   testpmd -w af:10.0,pflink_fullchk=1 -- -i
+
+- ``pflink_fullchk`` (default **0**)
+
+  When calling ``rte_eth_link_get_nowait()`` to get VF link status,
+  this option is used to control how VF synchronizes its status with
+  PF's. If set, VF will not only check the PF's physical link status
+  by reading related register, but also check the mailbox status. We
+  call this behavior as fully checking. And checking mailbox will
+  trigger PF's mailbox interrupt generation. If unset, the application
+  can get the VF's link status quickly by just reading the PF's link
+  status register, this will avoid the whole system's mailbox interrupt
+  generation.
+
+  ``rte_eth_link_get()`` will still use the mailbox method regardless
+  of the pflink_fullchk setting.
+
 RX Burst Size
 ^^^^^^^^^^^^^
 

drivers/net/ixgbe/ixgbe_ethdev.c

@@ -23,6 +23,7 @@
 #include <rte_bus_pci.h>
 #include <rte_branch_prediction.h>
 #include <rte_memory.h>
+#include <rte_kvargs.h>
 #include <rte_eal.h>
 #include <rte_alarm.h>
 #include <rte_ether.h>
@@ -127,6 +128,13 @@
 #define IXGBE_EXVET_VET_EXT_SHIFT              16
 #define IXGBE_DMATXCTL_VT_MASK                 0xFFFF0000
 
+#define IXGBEVF_DEVARG_PFLINK_FULLCHK		"pflink_fullchk"
+
+static const char * const ixgbevf_valid_arguments[] = {
+	IXGBEVF_DEVARG_PFLINK_FULLCHK,
+	NULL
+};
+
 static int eth_ixgbe_dev_init(struct rte_eth_dev *eth_dev, void *init_params);
 static int eth_ixgbe_dev_uninit(struct rte_eth_dev *eth_dev);
 static int ixgbe_fdir_filter_init(struct rte_eth_dev *eth_dev);
@@ -1550,6 +1558,45 @@ generate_random_mac_addr(struct rte_ether_addr *mac_addr)
 	memcpy(&mac_addr->addr_bytes[3], &random, 3);
 }
 
+static int
+devarg_handle_int(__rte_unused const char *key, const char *value,
+		  void *extra_args)
+{
+	uint16_t *n = extra_args;
+
+	if (value == NULL || extra_args == NULL)
+		return -EINVAL;
+
+	*n = (uint16_t)strtoul(value, NULL, 0);
+	if (*n == USHRT_MAX && errno == ERANGE)
+		return -1;
+
+	return 0;
+}
+
+static void
+ixgbevf_parse_devargs(struct ixgbe_adapter *adapter,
+		      struct rte_devargs *devargs)
+{
+	struct rte_kvargs *kvlist;
+	uint16_t pflink_fullchk;
+
+	if (devargs == NULL)
+		return;
+
+	kvlist = rte_kvargs_parse(devargs->args, ixgbevf_valid_arguments);
+	if (kvlist == NULL)
+		return;
+
+	if (rte_kvargs_count(kvlist, IXGBEVF_DEVARG_PFLINK_FULLCHK) == 1 &&
+	    rte_kvargs_process(kvlist, IXGBEVF_DEVARG_PFLINK_FULLCHK,
+			       devarg_handle_int, &pflink_fullchk) == 0 &&
+	    pflink_fullchk == 1)
+		adapter->pflink_fullchk = 1;
+
+	rte_kvargs_free(kvlist);
+}
+
 /*
  * Virtual Function device init
  */
@@ -1598,6 +1645,9 @@ eth_ixgbevf_dev_init(struct rte_eth_dev *eth_dev)
 		return 0;
 	}
 
+	ixgbevf_parse_devargs(eth_dev->data->dev_private,
+			      pci_dev->device.devargs);
+
 	rte_eth_copy_pci_info(eth_dev, pci_dev);
 
 	hw->device_id = pci_dev->id.device_id;
@@ -3908,6 +3958,8 @@ static int
 ixgbevf_check_link(struct ixgbe_hw *hw, ixgbe_link_speed *speed,
 		   int *link_up, int wait_to_complete)
 {
+	struct ixgbe_adapter *adapter = container_of(hw,
+						     struct ixgbe_adapter, hw);
 	struct ixgbe_mbx_info *mbx = &hw->mbx;
 	struct ixgbe_mac_info *mac = &hw->mac;
 	uint32_t links_reg, in_msg;
@@ -3968,6 +4020,15 @@ ixgbevf_check_link(struct ixgbe_hw *hw, ixgbe_link_speed *speed,
 		*speed = IXGBE_LINK_SPEED_UNKNOWN;
 	}
 
+	if (wait_to_complete == 0 && adapter->pflink_fullchk == 0) {
+		if (*speed == IXGBE_LINK_SPEED_UNKNOWN)
+			mac->get_link_status = true;
+		else
+			mac->get_link_status = false;
+
+		goto out;
+	}
+
 	/* if the read failed it could just be a mailbox collision, best wait
 	 * until we are called again and don't report an error
 	 */
@@ -8660,6 +8721,8 @@ RTE_PMD_REGISTER_KMOD_DEP(net_ixgbe, "* igb_uio | uio_pci_generic | vfio-pci");
 RTE_PMD_REGISTER_PCI(net_ixgbe_vf, rte_ixgbevf_pmd);
 RTE_PMD_REGISTER_PCI_TABLE(net_ixgbe_vf, pci_id_ixgbevf_map);
 RTE_PMD_REGISTER_KMOD_DEP(net_ixgbe_vf, "* igb_uio | vfio-pci");
+RTE_PMD_REGISTER_PARAM_STRING(net_ixgbe_vf,
+			      IXGBEVF_DEVARG_PFLINK_FULLCHK "=<0|1>");
 
 RTE_INIT(ixgbe_init_log)
 {

drivers/net/ixgbe/ixgbe_ethdev.h

@@ -498,6 +498,11 @@ struct ixgbe_adapter {
 
 	/* For RSS reta table update */
 	uint8_t rss_reta_updated;
+
+	/* Used for VF link sync with PF's physical and logical (by checking
+	 * mailbox status) link status.
+	 */
+	uint8_t pflink_fullchk;
 };
 
 struct ixgbe_vf_representor {