Commit | Line | Data |
---|---|---|
a72232ea VS |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Miscellaneous cgroup controller | |
4 | * | |
5 | * Copyright 2020 Google LLC | |
6 | * Author: Vipin Sharma <vipinsh@google.com> | |
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 */ | |
20 | static const char *const misc_res_name[] = { | |
7aef27f0 VS |
21 | #ifdef CONFIG_KVM_AMD_SEV |
22 | /* AMD SEV ASIDs resource */ | |
23 | "sev", | |
24 | /* AMD SEV-ES ASIDs resource */ | |
25 | "sev_es", | |
26 | #endif | |
a72232ea VS |
27 | }; |
28 | ||
29 | /* Root misc cgroup */ | |
30 | static 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 | */ | |
40 | static 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 | */ | |
51 | static 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 | */ | |
65 | static 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 | */ | |
77 | unsigned 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 | } | |
84 | EXPORT_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 | */ | |
98 | int 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 | } | |
106 | EXPORT_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 | */ | |
116 | static 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 | */ | |
140 | int 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])) { | |
a72232ea VS |
160 | ret = -EBUSY; |
161 | goto err_charge; | |
162 | } | |
163 | } | |
164 | return 0; | |
165 | ||
166 | err_charge: | |
f279294b CX |
167 | for (j = i; j; j = parent_misc(j)) { |
168 | atomic_long_inc(&j->res[type].events); | |
169 | cgroup_file_notify(&j->events_file); | |
170 | } | |
171 | ||
a72232ea VS |
172 | for (j = cg; j != i; j = parent_misc(j)) |
173 | misc_cg_cancel_charge(type, j, amount); | |
174 | misc_cg_cancel_charge(type, i, amount); | |
175 | return ret; | |
176 | } | |
177 | EXPORT_SYMBOL_GPL(misc_cg_try_charge); | |
178 | ||
179 | /** | |
180 | * misc_cg_uncharge() - Uncharge the misc cgroup. | |
181 | * @type: Misc res type which was charged. | |
182 | * @cg: Misc cgroup which will be uncharged. | |
183 | * @amount: Charged amount. | |
184 | * | |
185 | * Context: Any context. | |
186 | */ | |
187 | void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg, | |
188 | unsigned long amount) | |
189 | { | |
190 | struct misc_cg *i; | |
191 | ||
192 | if (!(amount && valid_type(type) && cg)) | |
193 | return; | |
194 | ||
195 | for (i = cg; i; i = parent_misc(i)) | |
196 | misc_cg_cancel_charge(type, i, amount); | |
197 | } | |
198 | EXPORT_SYMBOL_GPL(misc_cg_uncharge); | |
199 | ||
200 | /** | |
201 | * misc_cg_max_show() - Show the misc cgroup max limit. | |
202 | * @sf: Interface file | |
203 | * @v: Arguments passed | |
204 | * | |
205 | * Context: Any context. | |
206 | * Return: 0 to denote successful print. | |
207 | */ | |
208 | static int misc_cg_max_show(struct seq_file *sf, void *v) | |
209 | { | |
210 | int i; | |
211 | struct misc_cg *cg = css_misc(seq_css(sf)); | |
212 | unsigned long max; | |
213 | ||
214 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
215 | if (READ_ONCE(misc_res_capacity[i])) { | |
216 | max = READ_ONCE(cg->res[i].max); | |
217 | if (max == MAX_NUM) | |
218 | seq_printf(sf, "%s max\n", misc_res_name[i]); | |
219 | else | |
220 | seq_printf(sf, "%s %lu\n", misc_res_name[i], | |
221 | max); | |
222 | } | |
223 | } | |
224 | ||
225 | return 0; | |
226 | } | |
227 | ||
228 | /** | |
229 | * misc_cg_max_write() - Update the maximum limit of the cgroup. | |
230 | * @of: Handler for the file. | |
231 | * @buf: Data from the user. It should be either "max", 0, or a positive | |
232 | * integer. | |
233 | * @nbytes: Number of bytes of the data. | |
234 | * @off: Offset in the file. | |
235 | * | |
236 | * User can pass data like: | |
237 | * echo sev 23 > misc.max, OR | |
238 | * echo sev max > misc.max | |
239 | * | |
240 | * Context: Any context. | |
241 | * Return: | |
242 | * * >= 0 - Number of bytes processed in the input. | |
243 | * * -EINVAL - If buf is not valid. | |
244 | * * -ERANGE - If number is bigger than the unsigned long capacity. | |
245 | */ | |
246 | static ssize_t misc_cg_max_write(struct kernfs_open_file *of, char *buf, | |
247 | size_t nbytes, loff_t off) | |
248 | { | |
249 | struct misc_cg *cg; | |
250 | unsigned long max; | |
251 | int ret = 0, i; | |
252 | enum misc_res_type type = MISC_CG_RES_TYPES; | |
253 | char *token; | |
254 | ||
255 | buf = strstrip(buf); | |
256 | token = strsep(&buf, " "); | |
257 | ||
258 | if (!token || !buf) | |
259 | return -EINVAL; | |
260 | ||
261 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
262 | if (!strcmp(misc_res_name[i], token)) { | |
263 | type = i; | |
264 | break; | |
265 | } | |
266 | } | |
267 | ||
268 | if (type == MISC_CG_RES_TYPES) | |
269 | return -EINVAL; | |
270 | ||
271 | if (!strcmp(MAX_STR, buf)) { | |
272 | max = MAX_NUM; | |
273 | } else { | |
274 | ret = kstrtoul(buf, 0, &max); | |
275 | if (ret) | |
276 | return ret; | |
277 | } | |
278 | ||
279 | cg = css_misc(of_css(of)); | |
280 | ||
281 | if (READ_ONCE(misc_res_capacity[type])) | |
282 | WRITE_ONCE(cg->res[type].max, max); | |
283 | else | |
284 | ret = -EINVAL; | |
285 | ||
286 | return ret ? ret : nbytes; | |
287 | } | |
288 | ||
289 | /** | |
290 | * misc_cg_current_show() - Show the current usage of the misc cgroup. | |
291 | * @sf: Interface file | |
292 | * @v: Arguments passed | |
293 | * | |
294 | * Context: Any context. | |
295 | * Return: 0 to denote successful print. | |
296 | */ | |
297 | static int misc_cg_current_show(struct seq_file *sf, void *v) | |
298 | { | |
299 | int i; | |
300 | unsigned long usage; | |
301 | struct misc_cg *cg = css_misc(seq_css(sf)); | |
302 | ||
303 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
304 | usage = atomic_long_read(&cg->res[i].usage); | |
305 | if (READ_ONCE(misc_res_capacity[i]) || usage) | |
306 | seq_printf(sf, "%s %lu\n", misc_res_name[i], usage); | |
307 | } | |
308 | ||
309 | return 0; | |
310 | } | |
311 | ||
312 | /** | |
313 | * misc_cg_capacity_show() - Show the total capacity of misc res on the host. | |
314 | * @sf: Interface file | |
315 | * @v: Arguments passed | |
316 | * | |
317 | * Only present in the root cgroup directory. | |
318 | * | |
319 | * Context: Any context. | |
320 | * Return: 0 to denote successful print. | |
321 | */ | |
322 | static int misc_cg_capacity_show(struct seq_file *sf, void *v) | |
323 | { | |
324 | int i; | |
325 | unsigned long cap; | |
326 | ||
327 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
328 | cap = READ_ONCE(misc_res_capacity[i]); | |
329 | if (cap) | |
330 | seq_printf(sf, "%s %lu\n", misc_res_name[i], cap); | |
331 | } | |
332 | ||
333 | return 0; | |
334 | } | |
335 | ||
f279294b CX |
336 | static int misc_events_show(struct seq_file *sf, void *v) |
337 | { | |
338 | struct misc_cg *cg = css_misc(seq_css(sf)); | |
339 | unsigned long events, i; | |
340 | ||
341 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
342 | events = atomic_long_read(&cg->res[i].events); | |
343 | if (READ_ONCE(misc_res_capacity[i]) || events) | |
344 | seq_printf(sf, "%s.max %lu\n", misc_res_name[i], events); | |
345 | } | |
346 | return 0; | |
347 | } | |
348 | ||
a72232ea VS |
349 | /* Misc cgroup interface files */ |
350 | static struct cftype misc_cg_files[] = { | |
351 | { | |
352 | .name = "max", | |
353 | .write = misc_cg_max_write, | |
354 | .seq_show = misc_cg_max_show, | |
355 | .flags = CFTYPE_NOT_ON_ROOT, | |
356 | }, | |
357 | { | |
358 | .name = "current", | |
359 | .seq_show = misc_cg_current_show, | |
a72232ea VS |
360 | }, |
361 | { | |
362 | .name = "capacity", | |
363 | .seq_show = misc_cg_capacity_show, | |
364 | .flags = CFTYPE_ONLY_ON_ROOT, | |
365 | }, | |
f279294b CX |
366 | { |
367 | .name = "events", | |
368 | .flags = CFTYPE_NOT_ON_ROOT, | |
369 | .file_offset = offsetof(struct misc_cg, events_file), | |
370 | .seq_show = misc_events_show, | |
371 | }, | |
a72232ea VS |
372 | {} |
373 | }; | |
374 | ||
375 | /** | |
376 | * misc_cg_alloc() - Allocate misc cgroup. | |
377 | * @parent_css: Parent cgroup. | |
378 | * | |
379 | * Context: Process context. | |
380 | * Return: | |
381 | * * struct cgroup_subsys_state* - css of the allocated cgroup. | |
382 | * * ERR_PTR(-ENOMEM) - No memory available to allocate. | |
383 | */ | |
384 | static struct cgroup_subsys_state * | |
385 | misc_cg_alloc(struct cgroup_subsys_state *parent_css) | |
386 | { | |
387 | enum misc_res_type i; | |
388 | struct misc_cg *cg; | |
389 | ||
390 | if (!parent_css) { | |
391 | cg = &root_cg; | |
392 | } else { | |
393 | cg = kzalloc(sizeof(*cg), GFP_KERNEL); | |
394 | if (!cg) | |
395 | return ERR_PTR(-ENOMEM); | |
396 | } | |
397 | ||
398 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
399 | WRITE_ONCE(cg->res[i].max, MAX_NUM); | |
400 | atomic_long_set(&cg->res[i].usage, 0); | |
401 | } | |
402 | ||
403 | return &cg->css; | |
404 | } | |
405 | ||
406 | /** | |
407 | * misc_cg_free() - Free the misc cgroup. | |
408 | * @css: cgroup subsys object. | |
409 | * | |
410 | * Context: Any context. | |
411 | */ | |
412 | static void misc_cg_free(struct cgroup_subsys_state *css) | |
413 | { | |
414 | kfree(css_misc(css)); | |
415 | } | |
416 | ||
417 | /* Cgroup controller callbacks */ | |
418 | struct cgroup_subsys misc_cgrp_subsys = { | |
419 | .css_alloc = misc_cg_alloc, | |
420 | .css_free = misc_cg_free, | |
421 | .legacy_cftypes = misc_cg_files, | |
422 | .dfl_cftypes = misc_cg_files, | |
423 | }; |