1 // SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
2 /* Copyright (c) 2021, NVIDIA CORPORATION & AFFILIATES. All rights reserved. */
3
4 #include "mlx5_core.h"
5 #include "mlx5_irq.h"
6 #include "pci_irq.h"
7
cpu_put(struct mlx5_irq_pool * pool,int cpu)8 static void cpu_put(struct mlx5_irq_pool *pool, int cpu)
9 {
10 pool->irqs_per_cpu[cpu]--;
11 }
12
cpu_get(struct mlx5_irq_pool * pool,int cpu)13 static void cpu_get(struct mlx5_irq_pool *pool, int cpu)
14 {
15 pool->irqs_per_cpu[cpu]++;
16 }
17
18 /* Gets the least loaded CPU. e.g.: the CPU with least IRQs bound to it */
cpu_get_least_loaded(struct mlx5_irq_pool * pool,const struct cpumask * req_mask)19 static int cpu_get_least_loaded(struct mlx5_irq_pool *pool,
20 const struct cpumask *req_mask)
21 {
22 int best_cpu = -1;
23 int cpu;
24
25 for_each_cpu_and(cpu, req_mask, cpu_online_mask) {
26 /* CPU has zero IRQs on it. No need to search any more CPUs. */
27 if (!pool->irqs_per_cpu[cpu]) {
28 best_cpu = cpu;
29 break;
30 }
31 if (best_cpu < 0)
32 best_cpu = cpu;
33 if (pool->irqs_per_cpu[cpu] < pool->irqs_per_cpu[best_cpu])
34 best_cpu = cpu;
35 }
36 if (best_cpu == -1) {
37 /* There isn't online CPUs in req_mask */
38 mlx5_core_err(pool->dev, "NO online CPUs in req_mask (%*pbl)\n",
39 cpumask_pr_args(req_mask));
40 best_cpu = cpumask_first(cpu_online_mask);
41 }
42 pool->irqs_per_cpu[best_cpu]++;
43 return best_cpu;
44 }
45
46 /* Creating an IRQ from irq_pool */
47 static struct mlx5_irq *
irq_pool_request_irq(struct mlx5_irq_pool * pool,struct irq_affinity_desc * af_desc)48 irq_pool_request_irq(struct mlx5_irq_pool *pool, struct irq_affinity_desc *af_desc)
49 {
50 struct irq_affinity_desc auto_desc = {};
51 u32 irq_index;
52 int err;
53
54 err = xa_alloc(&pool->irqs, &irq_index, NULL, pool->xa_num_irqs, GFP_KERNEL);
55 if (err)
56 return ERR_PTR(err);
57 if (pool->irqs_per_cpu) {
58 if (cpumask_weight(&af_desc->mask) > 1)
59 /* if req_mask contain more then one CPU, set the least loadad CPU
60 * of req_mask
61 */
62 cpumask_set_cpu(cpu_get_least_loaded(pool, &af_desc->mask),
63 &auto_desc.mask);
64 else
65 cpu_get(pool, cpumask_first(&af_desc->mask));
66 }
67 return mlx5_irq_alloc(pool, irq_index,
68 cpumask_empty(&auto_desc.mask) ? af_desc : &auto_desc,
69 NULL);
70 }
71
72 /* Looking for the IRQ with the smallest refcount that fits req_mask.
73 * If pool is sf_comp_pool, then we are looking for an IRQ with any of the
74 * requested CPUs in req_mask.
75 * for example: req_mask = 0xf, irq0_mask = 0x10, irq1_mask = 0x1. irq0_mask
76 * isn't subset of req_mask, so we will skip it. irq1_mask is subset of req_mask,
77 * we don't skip it.
78 * If pool is sf_ctrl_pool, then all IRQs have the same mask, so any IRQ will
79 * fit. And since mask is subset of itself, we will pass the first if bellow.
80 */
81 static struct mlx5_irq *
irq_pool_find_least_loaded(struct mlx5_irq_pool * pool,const struct cpumask * req_mask)82 irq_pool_find_least_loaded(struct mlx5_irq_pool *pool, const struct cpumask *req_mask)
83 {
84 int start = pool->xa_num_irqs.min;
85 int end = pool->xa_num_irqs.max;
86 struct mlx5_irq *irq = NULL;
87 struct mlx5_irq *iter;
88 int irq_refcount = 0;
89 unsigned long index;
90
91 lockdep_assert_held(&pool->lock);
92 xa_for_each_range(&pool->irqs, index, iter, start, end) {
93 struct cpumask *iter_mask = mlx5_irq_get_affinity_mask(iter);
94 int iter_refcount = mlx5_irq_read_locked(iter);
95
96 if (!cpumask_subset(iter_mask, req_mask))
97 /* skip IRQs with a mask which is not subset of req_mask */
98 continue;
99 if (iter_refcount < pool->min_threshold)
100 /* If we found an IRQ with less than min_thres, return it */
101 return iter;
102 if (!irq || iter_refcount < irq_refcount) {
103 /* In case we won't find an IRQ with less than min_thres,
104 * keep a pointer to the least used IRQ
105 */
106 irq_refcount = iter_refcount;
107 irq = iter;
108 }
109 }
110 return irq;
111 }
112
113 /**
114 * mlx5_irq_affinity_request - request an IRQ according to the given mask.
115 * @pool: IRQ pool to request from.
116 * @af_desc: affinity descriptor for this IRQ.
117 *
118 * This function returns a pointer to IRQ, or ERR_PTR in case of error.
119 */
120 struct mlx5_irq *
mlx5_irq_affinity_request(struct mlx5_irq_pool * pool,struct irq_affinity_desc * af_desc)121 mlx5_irq_affinity_request(struct mlx5_irq_pool *pool, struct irq_affinity_desc *af_desc)
122 {
123 struct mlx5_irq *least_loaded_irq, *new_irq;
124
125 mutex_lock(&pool->lock);
126 least_loaded_irq = irq_pool_find_least_loaded(pool, &af_desc->mask);
127 if (least_loaded_irq &&
128 mlx5_irq_read_locked(least_loaded_irq) < pool->min_threshold)
129 goto out;
130 /* We didn't find an IRQ with less than min_thres, try to allocate a new IRQ */
131 new_irq = irq_pool_request_irq(pool, af_desc);
132 if (IS_ERR(new_irq)) {
133 if (!least_loaded_irq) {
134 /* We failed to create an IRQ and we didn't find an IRQ */
135 mlx5_core_err(pool->dev, "Didn't find a matching IRQ. err = %ld\n",
136 PTR_ERR(new_irq));
137 mutex_unlock(&pool->lock);
138 return new_irq;
139 }
140 /* We failed to create a new IRQ for the requested affinity,
141 * sharing existing IRQ.
142 */
143 goto out;
144 }
145 least_loaded_irq = new_irq;
146 goto unlock;
147 out:
148 mlx5_irq_get_locked(least_loaded_irq);
149 if (mlx5_irq_read_locked(least_loaded_irq) > pool->max_threshold)
150 mlx5_core_dbg(pool->dev, "IRQ %u overloaded, pool_name: %s, %u EQs on this irq\n",
151 pci_irq_vector(pool->dev->pdev,
152 mlx5_irq_get_index(least_loaded_irq)), pool->name,
153 mlx5_irq_read_locked(least_loaded_irq) / MLX5_EQ_REFS_PER_IRQ);
154 unlock:
155 mutex_unlock(&pool->lock);
156 return least_loaded_irq;
157 }
158
mlx5_irq_affinity_irq_release(struct mlx5_core_dev * dev,struct mlx5_irq * irq)159 void mlx5_irq_affinity_irq_release(struct mlx5_core_dev *dev, struct mlx5_irq *irq)
160 {
161 struct mlx5_irq_pool *pool = mlx5_irq_pool_get(dev);
162 int cpu;
163
164 cpu = cpumask_first(mlx5_irq_get_affinity_mask(irq));
165 synchronize_irq(pci_irq_vector(pool->dev->pdev,
166 mlx5_irq_get_index(irq)));
167 if (mlx5_irq_put(irq))
168 if (pool->irqs_per_cpu)
169 cpu_put(pool, cpu);
170 }
171