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 | |
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 * |
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(n: nvecs, size: 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 this_vecs = affd->set_size[i]; |
73 | int j; |
74 | struct cpumask *result = group_cpus_evenly(numgrps: this_vecs); |
75 | |
76 | if (!result) { |
77 | kfree(objp: masks); |
78 | return NULL; |
79 | } |
80 | |
81 | for (j = 0; j < this_vecs; j++) |
82 | cpumask_copy(dstp: &masks[curvec + j].mask, srcp: &result[j]); |
83 | kfree(objp: 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(dstp: &masks[curvec].mask, srcp: 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 | */ |
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 | |