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
12static 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 */
25struct irq_affinity_desc *
26irq_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(dstp: &masks[curvec].mask, srcp: 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 nr_masks, this_vecs = affd->set_size[i];
73 struct cpumask *result = group_cpus_evenly(numgrps: this_vecs, nummasks: &nr_masks);
74
75 if (!result) {
76 kfree(objp: masks);
77 return NULL;
78 }
79
80 for (int j = 0; j < nr_masks; j++)
81 cpumask_copy(dstp: &masks[curvec + j].mask, srcp: &result[j]);
82 kfree(objp: result);
83
84 curvec += nr_masks;
85 usedvecs += nr_masks;
86 }
87
88 /* Fill out vectors at the end that don't need affinity */
89 if (usedvecs >= affvecs)
90 curvec = affd->pre_vectors + affvecs;
91 else
92 curvec = affd->pre_vectors + usedvecs;
93 for (; curvec < nvecs; curvec++)
94 cpumask_copy(dstp: &masks[curvec].mask, srcp: irq_default_affinity);
95
96 /* Mark the managed interrupts */
97 for (i = affd->pre_vectors; i < nvecs - affd->post_vectors; i++)
98 masks[i].is_managed = 1;
99
100 return masks;
101}
102
103/**
104 * irq_calc_affinity_vectors - Calculate the optimal number of vectors
105 * @minvec: The minimum number of vectors available
106 * @maxvec: The maximum number of vectors available
107 * @affd: Description of the affinity requirements
108 */
109unsigned int irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
110 const struct irq_affinity *affd)
111{
112 unsigned int resv = affd->pre_vectors + affd->post_vectors;
113 unsigned int set_vecs;
114
115 if (resv > minvec)
116 return 0;
117
118 if (affd->calc_sets) {
119 set_vecs = maxvec - resv;
120 } else {
121 cpus_read_lock();
122 set_vecs = cpumask_weight(cpu_possible_mask);
123 cpus_read_unlock();
124 }
125
126 return resv + min(set_vecs, maxvec - resv);
127}
128