[PATCH net-next 11/12] ice: Improve MSI-X fallback logic

[Tony Nguyen]

Currently if the driver is unable to get all the MSI-X vectors it wants, it
falls back to the minimum configuration which equates to a single Tx/Rx
traffic queue pair. Instead of using the minimum configuration, if given
more vectors than the minimum, utilize those vectors for additional traffic
queues after accounting for other interrupts.

Signed-off-by: Tony Nguyen <anthony.l.ngu...@intel.com>
Tested-by: Tony Brelinski <tonyx.brelin...@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_main.c | 40 ++++++++++++++---------
 1 file changed, 25 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c 
b/drivers/net/ethernet/intel/ice/ice_main.c
index 0bc0cd9ba188..813ec6b8ac23 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -3391,28 +3391,20 @@ static int ice_init_pf(struct ice_pf *pf)
  */
 static int ice_ena_msix_range(struct ice_pf *pf)
 {
+       int v_left, v_actual, v_other, v_budget = 0;
        struct device *dev = ice_pf_to_dev(pf);
-       int v_left, v_actual, v_budget = 0;
        int needed, err, i;
 
        v_left = pf->hw.func_caps.common_cap.num_msix_vectors;
 
-       /* reserve one vector for miscellaneous handler */
-       needed = 1;
+       /* reserve for LAN miscellaneous handler */
+       needed = ICE_MIN_LAN_OICR_MSIX;
        if (v_left < needed)
                goto no_hw_vecs_left_err;
        v_budget += needed;
        v_left -= needed;
 
-       /* reserve vectors for LAN traffic */
-       needed = min_t(int, num_online_cpus(), v_left);
-       if (v_left < needed)
-               goto no_hw_vecs_left_err;
-       pf->num_lan_msix = needed;
-       v_budget += needed;
-       v_left -= needed;
-
-       /* reserve one vector for flow director */
+       /* reserve for flow director */
        if (test_bit(ICE_FLAG_FD_ENA, pf->flags)) {
                needed = ICE_FDIR_MSIX;
                if (v_left < needed)
@@ -3421,9 +3413,19 @@ static int ice_ena_msix_range(struct ice_pf *pf)
                v_left -= needed;
        }
 
+       /* total used for non-traffic vectors */
+       v_other = v_budget;
+
+       /* reserve vectors for LAN traffic */
+       needed = min_t(int, num_online_cpus(), v_left);
+       if (v_left < needed)
+               goto no_hw_vecs_left_err;
+       pf->num_lan_msix = needed;
+       v_budget += needed;
+       v_left -= needed;
+
        pf->msix_entries = devm_kcalloc(dev, v_budget,
                                        sizeof(*pf->msix_entries), GFP_KERNEL);
-
        if (!pf->msix_entries) {
                err = -ENOMEM;
                goto exit_err;
@@ -3435,7 +3437,6 @@ static int ice_ena_msix_range(struct ice_pf *pf)
        /* actually reserve the vectors */
        v_actual = pci_enable_msix_range(pf->pdev, pf->msix_entries,
                                         ICE_MIN_MSIX, v_budget);
-
        if (v_actual < 0) {
                dev_err(dev, "unable to reserve MSI-X vectors\n");
                err = v_actual;
@@ -3452,7 +3453,16 @@ static int ice_ena_msix_range(struct ice_pf *pf)
                        err = -ERANGE;
                        goto msix_err;
                } else {
-                       pf->num_lan_msix = ICE_MIN_LAN_TXRX_MSIX;
+                       int v_traffic = v_actual - v_other;
+
+                       if (v_actual == ICE_MIN_MSIX ||
+                           v_traffic < ICE_MIN_LAN_TXRX_MSIX)
+                               pf->num_lan_msix = ICE_MIN_LAN_TXRX_MSIX;
+                       else
+                               pf->num_lan_msix = v_traffic;
+
+                       dev_notice(dev, "Enabled %d MSI-X vectors for LAN 
traffic.\n",
+                                  pf->num_lan_msix);
                }
        }
 
-- 
2.26.2