i40e: add interrupt test

Add a quick ethtool test for interrupts using the SW interrupt.
Also, change the loopback test (for now) to not report failure.

Change-Id: Id8ef154b82475e3163087a8d1df01dfec4d529fc
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index db626e0..d60673e 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -2752,6 +2752,11 @@
 
 	ena_mask = rd32(hw, I40E_PFINT_ICR0_ENA);
 
+	/* if interrupt but no bits showing, must be SWINT */
+	if (((icr0 & ~I40E_PFINT_ICR0_INTEVENT_MASK) == 0) ||
+	    (icr0 & I40E_PFINT_ICR0_SWINT_MASK))
+		pf->sw_int_count++;
+
 	/* only q0 is used in MSI/Legacy mode, and none are used in MSIX */
 	if (icr0 & I40E_PFINT_ICR0_QUEUE_0_MASK) {