1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2016 Thomas Gleixner.
4 * Copyright (C) 2016-2017 Christoph Hellwig.
5 */
6 #include <linux/interrupt.h>
7 #include <linux/kernel.h>
8 #include <linux/slab.h>
9 #include <linux/cpu.h>
10 #include <linux/group_cpus.h>
11
default_calc_sets(struct irq_affinity * affd,unsigned int affvecs)12 static void default_calc_sets(struct irq_affinity *affd, unsigned int affvecs)
13 {
14 affd->nr_sets = 1;
15 affd->set_size[0] = affvecs;
16 }
17
18 /**
19 * irq_create_affinity_masks - Create affinity masks for multiqueue spreading
20 * @nvecs: The total number of vectors
21 * @affd: Description of the affinity requirements
22 *
23 * Returns the irq_affinity_desc pointer or NULL if allocation failed.
24 */
25 struct irq_affinity_desc *
irq_create_affinity_masks(unsigned int nvecs,struct irq_affinity * affd)26 irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
27 {
28 unsigned int affvecs, curvec, usedvecs, i;
29 struct irq_affinity_desc *masks = NULL;
30
31 /*
32 * Determine the number of vectors which need interrupt affinities
33 * assigned. If the pre/post request exhausts the available vectors
34 * then nothing to do here except for invoking the calc_sets()
35 * callback so the device driver can adjust to the situation.
36 */
37 if (nvecs > affd->pre_vectors + affd->post_vectors)
38 affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
39 else
40 affvecs = 0;
41
42 /*
43 * Simple invocations do not provide a calc_sets() callback. Install
44 * the generic one.
45 */
46 if (!affd->calc_sets)
47 affd->calc_sets = default_calc_sets;
48
49 /* Recalculate the sets */
50 affd->calc_sets(affd, affvecs);
51
52 if (WARN_ON_ONCE(affd->nr_sets > IRQ_AFFINITY_MAX_SETS))
53 return NULL;
54
55 /* Nothing to assign? */
56 if (!affvecs)
57 return NULL;
58
59 masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
60 if (!masks)
61 return NULL;
62
63 /* Fill out vectors at the beginning that don't need affinity */
64 for (curvec = 0; curvec < affd->pre_vectors; curvec++)
65 cpumask_copy(&masks[curvec].mask, irq_default_affinity);
66
67 /*
68 * Spread on present CPUs starting from affd->pre_vectors. If we
69 * have multiple sets, build each sets affinity mask separately.
70 */
71 for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) {
72 unsigned int this_vecs = affd->set_size[i];
73 int j;
74 struct cpumask *result = group_cpus_evenly(this_vecs);
75
76 if (!result) {
77 kfree(masks);
78 return NULL;
79 }
80
81 for (j = 0; j < this_vecs; j++)
82 cpumask_copy(&masks[curvec + j].mask, &result[j]);
83 kfree(result);
84
85 curvec += this_vecs;
86 usedvecs += this_vecs;
87 }
88
89 /* Fill out vectors at the end that don't need affinity */
90 if (usedvecs >= affvecs)
91 curvec = affd->pre_vectors + affvecs;
92 else
93 curvec = affd->pre_vectors + usedvecs;
94 for (; curvec < nvecs; curvec++)
95 cpumask_copy(&masks[curvec].mask, irq_default_affinity);
96
97 /* Mark the managed interrupts */
98 for (i = affd->pre_vectors; i < nvecs - affd->post_vectors; i++)
99 masks[i].is_managed = 1;
100
101 return masks;
102 }
103
104 /**
105 * irq_calc_affinity_vectors - Calculate the optimal number of vectors
106 * @minvec: The minimum number of vectors available
107 * @maxvec: The maximum number of vectors available
108 * @affd: Description of the affinity requirements
109 */
irq_calc_affinity_vectors(unsigned int minvec,unsigned int maxvec,const struct irq_affinity * affd)110 unsigned int irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
111 const struct irq_affinity *affd)
112 {
113 unsigned int resv = affd->pre_vectors + affd->post_vectors;
114 unsigned int set_vecs;
115
116 if (resv > minvec)
117 return 0;
118
119 if (affd->calc_sets) {
120 set_vecs = maxvec - resv;
121 } else {
122 cpus_read_lock();
123 set_vecs = cpumask_weight(cpu_possible_mask);
124 cpus_read_unlock();
125 }
126
127 return resv + min(set_vecs, maxvec - resv);
128 }
129
