i40e: rework vector reservation

The initial problem solved here is that the vector allocation was trying
too hard to save vectors for VMDq, to the point of not giving the PF enough
when in a tight situation such as an NPAR partition.  This change makes
sure that the PF will get all the queues and vectors it wants to fill
out its destiny.  Essentially, nothing is specially reserved for VMDq,
it simply gets whatever is left after the PF, FCoE, and FD sideband get
what they want.

Additionally, the calculations for the reservations were harder to follow
than necessary, so I've made it more straight forward.

Change-ID: I99b384f104535b686c690b8ef0a787559485c8d4
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -1541,7 +1541,7 @@ static void i40e_vsi_setup_queue_map(struct i40e_vsi *vsi,
 			vsi->tc_config.tc_info[i].qoffset = offset;
 			vsi->tc_config.tc_info[i].qcount = qcount;
 
-			/* find the power-of-2 of the number of queue pairs */
+			/* find the next higher power-of-2 of num queue pairs */
 			num_qps = qcount;
 			pow = 0;
 			while (num_qps && ((1 << pow) < qcount)) {
@@ -6940,7 +6940,7 @@ static int i40e_reserve_msix_vectors(struct i40e_pf *pf, int vectors)
 static int i40e_init_msix(struct i40e_pf *pf)
 {
 	struct i40e_hw *hw = &pf->hw;
-	int other_vecs = 0;
+	int vectors_left;
 	int v_budget, i;
 	int v_actual;
 
@@ -6964,25 +6964,62 @@ static int i40e_init_msix(struct i40e_pf *pf)
 	 * If we can't get what we want, we'll simplify to nearly nothing
 	 * and try again.  If that still fails, we punt.
 	 */
-	pf->num_lan_msix = min_t(int, num_online_cpus(),
-				 hw->func_caps.num_msix_vectors);
-	pf->num_vmdq_msix = pf->num_vmdq_qps;
-	other_vecs = 1;
-	other_vecs += (pf->num_vmdq_vsis * pf->num_vmdq_msix);
-	if (pf->flags & I40E_FLAG_FD_SB_ENABLED)
-		other_vecs++;
+	vectors_left = hw->func_caps.num_msix_vectors;
+	v_budget = 0;
+
+	/* reserve one vector for miscellaneous handler */
+	if (vectors_left) {
+		v_budget++;
+		vectors_left--;
+	}
 
-	/* Scale down if necessary, and the rings will share vectors */
-	pf->num_lan_msix = min_t(int, pf->num_lan_msix,
-			(hw->func_caps.num_msix_vectors - other_vecs));
-	v_budget = pf->num_lan_msix + other_vecs;
+	/* reserve vectors for the main PF traffic queues */
+	pf->num_lan_msix = min_t(int, num_online_cpus(), vectors_left);
+	vectors_left -= pf->num_lan_msix;
+	v_budget += pf->num_lan_msix;
+
+	/* reserve one vector for sideband flow director */
+	if (pf->flags & I40E_FLAG_FD_SB_ENABLED) {
+		if (vectors_left) {
+			v_budget++;
+			vectors_left--;
+		} else {
+			pf->flags &= ~I40E_FLAG_FD_SB_ENABLED;
+		}
+	}
 
 #ifdef I40E_FCOE
+	/* can we reserve enough for FCoE? */
 	if (pf->flags & I40E_FLAG_FCOE_ENABLED) {
+		if (!vectors_left)
+			pf->num_fcoe_msix = 0;
+		else if (vectors_left >= pf->num_fcoe_qps)
 			pf->num_fcoe_msix = pf->num_fcoe_qps;
+		else
+			pf->num_fcoe_msix = 1;
 		v_budget += pf->num_fcoe_msix;
+		vectors_left -= pf->num_fcoe_msix;
 	}
+
 #endif
+	/* any vectors left over go for VMDq support */
+	if (pf->flags & I40E_FLAG_VMDQ_ENABLED) {
+		int vmdq_vecs_wanted = pf->num_vmdq_vsis * pf->num_vmdq_qps;
+		int vmdq_vecs = min_t(int, vectors_left, vmdq_vecs_wanted);
+
+		/* if we're short on vectors for what's desired, we limit
+		 * the queues per vmdq.  If this is still more than are
+		 * available, the user will need to change the number of
+		 * queues/vectors used by the PF later with the ethtool
+		 * channels command
+		 */
+		if (vmdq_vecs < vmdq_vecs_wanted)
+			pf->num_vmdq_qps = 1;
+		pf->num_vmdq_msix = pf->num_vmdq_qps;
+
+		v_budget += vmdq_vecs;
+		vectors_left -= vmdq_vecs;
+	}
 
 	pf->msix_entries = kcalloc(v_budget, sizeof(struct msix_entry),
 				   GFP_KERNEL);
@@ -7028,6 +7065,8 @@ static int i40e_init_msix(struct i40e_pf *pf)
 		/* Scale vector usage down */
 		pf->num_vmdq_msix = 1;    /* force VMDqs to only one vector */
 		pf->num_vmdq_vsis = 1;
+		pf->num_vmdq_qps = 1;
+		pf->flags &= ~I40E_FLAG_FD_SB_ENABLED;
 
 		/* partition out the remaining vectors */
 		switch (vec) {
@@ -7053,10 +7092,8 @@ static int i40e_init_msix(struct i40e_pf *pf)
 				vec--;
 			}
 #endif
-			pf->num_lan_msix = min_t(int, (vec / 2),
-						 pf->num_lan_qps);
-			pf->num_vmdq_vsis = min_t(int, (vec - pf->num_lan_msix),
-						  I40E_DEFAULT_NUM_VMDQ_VSI);
+			/* give the rest to the PF */
+			pf->num_lan_msix = min_t(int, vec, pf->num_lan_qps);
 			break;
 		}
 	}