projects/linux·blob v5.13 · refs

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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Miscellaneous cgroup controller
4 *
5 * Copyright 2020 Google LLC
6 * Author: Vipin Sharma <[email protected]>
7 */
8
9#include <linux/limits.h>
10#include <linux/cgroup.h>
11#include <linux/errno.h>
12#include <linux/atomic.h>
13#include <linux/slab.h>
14#include <linux/misc_cgroup.h>
15
16#define MAX_STR "max"
17#define MAX_NUM ULONG_MAX
18
19/* Miscellaneous res name, keep it in sync with enum misc_res_type */
20static const char *const misc_res_name[] = {
21#ifdef CONFIG_KVM_AMD_SEV
22 /* AMD SEV ASIDs resource */
23 "sev",
24 /* AMD SEV-ES ASIDs resource */
25 "sev_es",
26#endif
27};
28
29/* Root misc cgroup */
30static struct misc_cg root_cg;
31
32/*
33 * Miscellaneous resources capacity for the entire machine. 0 capacity means
34 * resource is not initialized or not present in the host.
35 *
36 * root_cg.max and capacity are independent of each other. root_cg.max can be
37 * more than the actual capacity. We are using Limits resource distribution
38 * model of cgroup for miscellaneous controller.
39 */
40static unsigned long misc_res_capacity[MISC_CG_RES_TYPES];
41
42/**
43 * parent_misc() - Get the parent of the passed misc cgroup.
44 * @cgroup: cgroup whose parent needs to be fetched.
45 *
46 * Context: Any context.
47 * Return:
48 * * struct misc_cg* - Parent of the @cgroup.
49 * * %NULL - If @cgroup is null or the passed cgroup does not have a parent.
50 */
51static struct misc_cg *parent_misc(struct misc_cg *cgroup)
52{
53 return cgroup ? css_misc(cgroup->css.parent) : NULL;
54}
55
56/**
57 * valid_type() - Check if @type is valid or not.
58 * @type: misc res type.
59 *
60 * Context: Any context.
61 * Return:
62 * * true - If valid type.
63 * * false - If not valid type.
64 */
65static inline bool valid_type(enum misc_res_type type)
66{
67 return type >= 0 && type < MISC_CG_RES_TYPES;
68}
69
70/**
71 * misc_cg_res_total_usage() - Get the current total usage of the resource.
72 * @type: misc res type.
73 *
74 * Context: Any context.
75 * Return: Current total usage of the resource.
76 */
77unsigned long misc_cg_res_total_usage(enum misc_res_type type)
78{
79 if (valid_type(type))
80 return atomic_long_read(&root_cg.res[type].usage);
81
82 return 0;
83}
84EXPORT_SYMBOL_GPL(misc_cg_res_total_usage);
85
86/**
87 * misc_cg_set_capacity() - Set the capacity of the misc cgroup res.
88 * @type: Type of the misc res.
89 * @capacity: Supported capacity of the misc res on the host.
90 *
91 * If capacity is 0 then the charging a misc cgroup fails for that type.
92 *
93 * Context: Any context.
94 * Return:
95 * * %0 - Successfully registered the capacity.
96 * * %-EINVAL - If @type is invalid.
97 */
98int misc_cg_set_capacity(enum misc_res_type type, unsigned long capacity)
99{
100 if (!valid_type(type))
101 return -EINVAL;
102
103 WRITE_ONCE(misc_res_capacity[type], capacity);
104 return 0;
105}
106EXPORT_SYMBOL_GPL(misc_cg_set_capacity);
107
108/**
109 * misc_cg_cancel_charge() - Cancel the charge from the misc cgroup.
110 * @type: Misc res type in misc cg to cancel the charge from.
111 * @cg: Misc cgroup to cancel charge from.
112 * @amount: Amount to cancel.
113 *
114 * Context: Any context.
115 */
116static void misc_cg_cancel_charge(enum misc_res_type type, struct misc_cg *cg,
117 unsigned long amount)
118{
119 WARN_ONCE(atomic_long_add_negative(-amount, &cg->res[type].usage),
120 "misc cgroup resource %s became less than 0",
121 misc_res_name[type]);
122}
123
124/**
125 * misc_cg_try_charge() - Try charging the misc cgroup.
126 * @type: Misc res type to charge.
127 * @cg: Misc cgroup which will be charged.
128 * @amount: Amount to charge.
129 *
130 * Charge @amount to the misc cgroup. Caller must use the same cgroup during
131 * the uncharge call.
132 *
133 * Context: Any context.
134 * Return:
135 * * %0 - If successfully charged.
136 * * -EINVAL - If @type is invalid or misc res has 0 capacity.
137 * * -EBUSY - If max limit will be crossed or total usage will be more than the
138 * capacity.
139 */
140int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
141 unsigned long amount)
142{
143 struct misc_cg *i, *j;
144 int ret;
145 struct misc_res *res;
146 int new_usage;
147
148 if (!(valid_type(type) && cg && READ_ONCE(misc_res_capacity[type])))
149 return -EINVAL;
150
151 if (!amount)
152 return 0;
153
154 for (i = cg; i; i = parent_misc(i)) {
155 res = &i->res[type];
156
157 new_usage = atomic_long_add_return(amount, &res->usage);
158 if (new_usage > READ_ONCE(res->max) ||
159 new_usage > READ_ONCE(misc_res_capacity[type])) {
160 if (!res->failed) {
161 pr_info("cgroup: charge rejected by the misc controller for %s resource in ",
162 misc_res_name[type]);
163 pr_cont_cgroup_path(i->css.cgroup);
164 pr_cont("\n");
165 res->failed = true;
166 }
167 ret = -EBUSY;
168 goto err_charge;
169 }
170 }
171 return 0;
172
173err_charge:
174 for (j = cg; j != i; j = parent_misc(j))
175 misc_cg_cancel_charge(type, j, amount);
176 misc_cg_cancel_charge(type, i, amount);
177 return ret;
178}
179EXPORT_SYMBOL_GPL(misc_cg_try_charge);
180
181/**
182 * misc_cg_uncharge() - Uncharge the misc cgroup.
183 * @type: Misc res type which was charged.
184 * @cg: Misc cgroup which will be uncharged.
185 * @amount: Charged amount.
186 *
187 * Context: Any context.
188 */
189void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg,
190 unsigned long amount)
191{
192 struct misc_cg *i;
193
194 if (!(amount && valid_type(type) && cg))
195 return;
196
197 for (i = cg; i; i = parent_misc(i))
198 misc_cg_cancel_charge(type, i, amount);
199}
200EXPORT_SYMBOL_GPL(misc_cg_uncharge);
201
202/**
203 * misc_cg_max_show() - Show the misc cgroup max limit.
204 * @sf: Interface file
205 * @v: Arguments passed
206 *
207 * Context: Any context.
208 * Return: 0 to denote successful print.
209 */
210static int misc_cg_max_show(struct seq_file *sf, void *v)
211{
212 int i;
213 struct misc_cg *cg = css_misc(seq_css(sf));
214 unsigned long max;
215
216 for (i = 0; i < MISC_CG_RES_TYPES; i++) {
217 if (READ_ONCE(misc_res_capacity[i])) {
218 max = READ_ONCE(cg->res[i].max);
219 if (max == MAX_NUM)
220 seq_printf(sf, "%s max\n", misc_res_name[i]);
221 else
222 seq_printf(sf, "%s %lu\n", misc_res_name[i],
223 max);
224 }
225 }
226
227 return 0;
228}
229
230/**
231 * misc_cg_max_write() - Update the maximum limit of the cgroup.
232 * @of: Handler for the file.
233 * @buf: Data from the user. It should be either "max", 0, or a positive
234 * integer.
235 * @nbytes: Number of bytes of the data.
236 * @off: Offset in the file.
237 *
238 * User can pass data like:
239 * echo sev 23 > misc.max, OR
240 * echo sev max > misc.max
241 *
242 * Context: Any context.
243 * Return:
244 * * >= 0 - Number of bytes processed in the input.
245 * * -EINVAL - If buf is not valid.
246 * * -ERANGE - If number is bigger than the unsigned long capacity.
247 */
248static ssize_t misc_cg_max_write(struct kernfs_open_file *of, char *buf,
249 size_t nbytes, loff_t off)
250{
251 struct misc_cg *cg;
252 unsigned long max;
253 int ret = 0, i;
254 enum misc_res_type type = MISC_CG_RES_TYPES;
255 char *token;
256
257 buf = strstrip(buf);
258 token = strsep(&buf, " ");
259
260 if (!token || !buf)
261 return -EINVAL;
262
263 for (i = 0; i < MISC_CG_RES_TYPES; i++) {
264 if (!strcmp(misc_res_name[i], token)) {
265 type = i;
266 break;
267 }
268 }
269
270 if (type == MISC_CG_RES_TYPES)
271 return -EINVAL;
272
273 if (!strcmp(MAX_STR, buf)) {
274 max = MAX_NUM;
275 } else {
276 ret = kstrtoul(buf, 0, &max);
277 if (ret)
278 return ret;
279 }
280
281 cg = css_misc(of_css(of));
282
283 if (READ_ONCE(misc_res_capacity[type]))
284 WRITE_ONCE(cg->res[type].max, max);
285 else
286 ret = -EINVAL;
287
288 return ret ? ret : nbytes;
289}
290
291/**
292 * misc_cg_current_show() - Show the current usage of the misc cgroup.
293 * @sf: Interface file
294 * @v: Arguments passed
295 *
296 * Context: Any context.
297 * Return: 0 to denote successful print.
298 */
299static int misc_cg_current_show(struct seq_file *sf, void *v)
300{
301 int i;
302 unsigned long usage;
303 struct misc_cg *cg = css_misc(seq_css(sf));
304
305 for (i = 0; i < MISC_CG_RES_TYPES; i++) {
306 usage = atomic_long_read(&cg->res[i].usage);
307 if (READ_ONCE(misc_res_capacity[i]) || usage)
308 seq_printf(sf, "%s %lu\n", misc_res_name[i], usage);
309 }
310
311 return 0;
312}
313
314/**
315 * misc_cg_capacity_show() - Show the total capacity of misc res on the host.
316 * @sf: Interface file
317 * @v: Arguments passed
318 *
319 * Only present in the root cgroup directory.
320 *
321 * Context: Any context.
322 * Return: 0 to denote successful print.
323 */
324static int misc_cg_capacity_show(struct seq_file *sf, void *v)
325{
326 int i;
327 unsigned long cap;
328
329 for (i = 0; i < MISC_CG_RES_TYPES; i++) {
330 cap = READ_ONCE(misc_res_capacity[i]);
331 if (cap)
332 seq_printf(sf, "%s %lu\n", misc_res_name[i], cap);
333 }
334
335 return 0;
336}
337
338/* Misc cgroup interface files */
339static struct cftype misc_cg_files[] = {
340 {
341 .name = "max",
342 .write = misc_cg_max_write,
343 .seq_show = misc_cg_max_show,
344 .flags = CFTYPE_NOT_ON_ROOT,
345 },
346 {
347 .name = "current",
348 .seq_show = misc_cg_current_show,
349 .flags = CFTYPE_NOT_ON_ROOT,
350 },
351 {
352 .name = "capacity",
353 .seq_show = misc_cg_capacity_show,
354 .flags = CFTYPE_ONLY_ON_ROOT,
355 },
356 {}
357};
358
359/**
360 * misc_cg_alloc() - Allocate misc cgroup.
361 * @parent_css: Parent cgroup.
362 *
363 * Context: Process context.
364 * Return:
365 * * struct cgroup_subsys_state* - css of the allocated cgroup.
366 * * ERR_PTR(-ENOMEM) - No memory available to allocate.
367 */
368static struct cgroup_subsys_state *
369misc_cg_alloc(struct cgroup_subsys_state *parent_css)
370{
371 enum misc_res_type i;
372 struct misc_cg *cg;
373
374 if (!parent_css) {
375 cg = &root_cg;
376 } else {
377 cg = kzalloc(sizeof(*cg), GFP_KERNEL);
378 if (!cg)
379 return ERR_PTR(-ENOMEM);
380 }
381
382 for (i = 0; i < MISC_CG_RES_TYPES; i++) {
383 WRITE_ONCE(cg->res[i].max, MAX_NUM);
384 atomic_long_set(&cg->res[i].usage, 0);
385 }
386
387 return &cg->css;
388}
389
390/**
391 * misc_cg_free() - Free the misc cgroup.
392 * @css: cgroup subsys object.
393 *
394 * Context: Any context.
395 */
396static void misc_cg_free(struct cgroup_subsys_state *css)
397{
398 kfree(css_misc(css));
399}
400
401/* Cgroup controller callbacks */
402struct cgroup_subsys misc_cgrp_subsys = {
403 .css_alloc = misc_cg_alloc,
404 .css_free = misc_cg_free,
405 .legacy_cftypes = misc_cg_files,
406 .dfl_cftypes = misc_cg_files,
407};