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 U64_MAX |
18 | |
19 | /* Miscellaneous res name, keep it in sync with enum misc_res_type */ |
20 | static 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 */ |
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 u64 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(css: 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 | u64 misc_cg_res_total_usage(enum misc_res_type type) |
78 | { |
79 | if (valid_type(type)) |
80 | return atomic64_read(v: &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, u64 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 | u64 amount) |
118 | { |
119 | WARN_ONCE(atomic64_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, u64 amount) |
141 | { |
142 | struct misc_cg *i, *j; |
143 | int ret; |
144 | struct misc_res *res; |
145 | u64 new_usage; |
146 | |
147 | if (!(valid_type(type) && cg && READ_ONCE(misc_res_capacity[type]))) |
148 | return -EINVAL; |
149 | |
150 | if (!amount) |
151 | return 0; |
152 | |
153 | for (i = cg; i; i = parent_misc(cgroup: i)) { |
154 | res = &i->res[type]; |
155 | |
156 | new_usage = atomic64_add_return(i: amount, v: &res->usage); |
157 | if (new_usage > READ_ONCE(res->max) || |
158 | new_usage > READ_ONCE(misc_res_capacity[type])) { |
159 | ret = -EBUSY; |
160 | goto err_charge; |
161 | } |
162 | } |
163 | return 0; |
164 | |
165 | err_charge: |
166 | for (j = i; j; j = parent_misc(cgroup: j)) { |
167 | atomic64_inc(v: &j->res[type].events); |
168 | cgroup_file_notify(cfile: &j->events_file); |
169 | } |
170 | |
171 | for (j = cg; j != i; j = parent_misc(cgroup: j)) |
172 | misc_cg_cancel_charge(type, cg: j, amount); |
173 | misc_cg_cancel_charge(type, cg: i, amount); |
174 | return ret; |
175 | } |
176 | EXPORT_SYMBOL_GPL(misc_cg_try_charge); |
177 | |
178 | /** |
179 | * misc_cg_uncharge() - Uncharge the misc cgroup. |
180 | * @type: Misc res type which was charged. |
181 | * @cg: Misc cgroup which will be uncharged. |
182 | * @amount: Charged amount. |
183 | * |
184 | * Context: Any context. |
185 | */ |
186 | void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg, u64 amount) |
187 | { |
188 | struct misc_cg *i; |
189 | |
190 | if (!(amount && valid_type(type) && cg)) |
191 | return; |
192 | |
193 | for (i = cg; i; i = parent_misc(cgroup: i)) |
194 | misc_cg_cancel_charge(type, cg: i, amount); |
195 | } |
196 | EXPORT_SYMBOL_GPL(misc_cg_uncharge); |
197 | |
198 | /** |
199 | * misc_cg_max_show() - Show the misc cgroup max limit. |
200 | * @sf: Interface file |
201 | * @v: Arguments passed |
202 | * |
203 | * Context: Any context. |
204 | * Return: 0 to denote successful print. |
205 | */ |
206 | static int misc_cg_max_show(struct seq_file *sf, void *v) |
207 | { |
208 | int i; |
209 | struct misc_cg *cg = css_misc(css: seq_css(seq: sf)); |
210 | u64 max; |
211 | |
212 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { |
213 | if (READ_ONCE(misc_res_capacity[i])) { |
214 | max = READ_ONCE(cg->res[i].max); |
215 | if (max == MAX_NUM) |
216 | seq_printf(m: sf, fmt: "%s max\n" , misc_res_name[i]); |
217 | else |
218 | seq_printf(m: sf, fmt: "%s %llu\n" , misc_res_name[i], |
219 | max); |
220 | } |
221 | } |
222 | |
223 | return 0; |
224 | } |
225 | |
226 | /** |
227 | * misc_cg_max_write() - Update the maximum limit of the cgroup. |
228 | * @of: Handler for the file. |
229 | * @buf: Data from the user. It should be either "max", 0, or a positive |
230 | * integer. |
231 | * @nbytes: Number of bytes of the data. |
232 | * @off: Offset in the file. |
233 | * |
234 | * User can pass data like: |
235 | * echo sev 23 > misc.max, OR |
236 | * echo sev max > misc.max |
237 | * |
238 | * Context: Any context. |
239 | * Return: |
240 | * * >= 0 - Number of bytes processed in the input. |
241 | * * -EINVAL - If buf is not valid. |
242 | * * -ERANGE - If number is bigger than the u64 capacity. |
243 | */ |
244 | static ssize_t misc_cg_max_write(struct kernfs_open_file *of, char *buf, |
245 | size_t nbytes, loff_t off) |
246 | { |
247 | struct misc_cg *cg; |
248 | u64 max; |
249 | int ret = 0, i; |
250 | enum misc_res_type type = MISC_CG_RES_TYPES; |
251 | char *token; |
252 | |
253 | buf = strstrip(str: buf); |
254 | token = strsep(&buf, " " ); |
255 | |
256 | if (!token || !buf) |
257 | return -EINVAL; |
258 | |
259 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { |
260 | if (!strcmp(misc_res_name[i], token)) { |
261 | type = i; |
262 | break; |
263 | } |
264 | } |
265 | |
266 | if (type == MISC_CG_RES_TYPES) |
267 | return -EINVAL; |
268 | |
269 | if (!strcmp(MAX_STR, buf)) { |
270 | max = MAX_NUM; |
271 | } else { |
272 | ret = kstrtou64(s: buf, base: 0, res: &max); |
273 | if (ret) |
274 | return ret; |
275 | } |
276 | |
277 | cg = css_misc(css: of_css(of)); |
278 | |
279 | if (READ_ONCE(misc_res_capacity[type])) |
280 | WRITE_ONCE(cg->res[type].max, max); |
281 | else |
282 | ret = -EINVAL; |
283 | |
284 | return ret ? ret : nbytes; |
285 | } |
286 | |
287 | /** |
288 | * misc_cg_current_show() - Show the current usage of the misc cgroup. |
289 | * @sf: Interface file |
290 | * @v: Arguments passed |
291 | * |
292 | * Context: Any context. |
293 | * Return: 0 to denote successful print. |
294 | */ |
295 | static int misc_cg_current_show(struct seq_file *sf, void *v) |
296 | { |
297 | int i; |
298 | u64 usage; |
299 | struct misc_cg *cg = css_misc(css: seq_css(seq: sf)); |
300 | |
301 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { |
302 | usage = atomic64_read(v: &cg->res[i].usage); |
303 | if (READ_ONCE(misc_res_capacity[i]) || usage) |
304 | seq_printf(m: sf, fmt: "%s %llu\n" , misc_res_name[i], usage); |
305 | } |
306 | |
307 | return 0; |
308 | } |
309 | |
310 | /** |
311 | * misc_cg_capacity_show() - Show the total capacity of misc res on the host. |
312 | * @sf: Interface file |
313 | * @v: Arguments passed |
314 | * |
315 | * Only present in the root cgroup directory. |
316 | * |
317 | * Context: Any context. |
318 | * Return: 0 to denote successful print. |
319 | */ |
320 | static int misc_cg_capacity_show(struct seq_file *sf, void *v) |
321 | { |
322 | int i; |
323 | u64 cap; |
324 | |
325 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { |
326 | cap = READ_ONCE(misc_res_capacity[i]); |
327 | if (cap) |
328 | seq_printf(m: sf, fmt: "%s %llu\n" , misc_res_name[i], cap); |
329 | } |
330 | |
331 | return 0; |
332 | } |
333 | |
334 | static int misc_events_show(struct seq_file *sf, void *v) |
335 | { |
336 | struct misc_cg *cg = css_misc(css: seq_css(seq: sf)); |
337 | u64 events; |
338 | int i; |
339 | |
340 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { |
341 | events = atomic64_read(v: &cg->res[i].events); |
342 | if (READ_ONCE(misc_res_capacity[i]) || events) |
343 | seq_printf(m: sf, fmt: "%s.max %llu\n" , misc_res_name[i], events); |
344 | } |
345 | return 0; |
346 | } |
347 | |
348 | /* Misc cgroup interface files */ |
349 | static struct cftype misc_cg_files[] = { |
350 | { |
351 | .name = "max" , |
352 | .write = misc_cg_max_write, |
353 | .seq_show = misc_cg_max_show, |
354 | .flags = CFTYPE_NOT_ON_ROOT, |
355 | }, |
356 | { |
357 | .name = "current" , |
358 | .seq_show = misc_cg_current_show, |
359 | }, |
360 | { |
361 | .name = "capacity" , |
362 | .seq_show = misc_cg_capacity_show, |
363 | .flags = CFTYPE_ONLY_ON_ROOT, |
364 | }, |
365 | { |
366 | .name = "events" , |
367 | .flags = CFTYPE_NOT_ON_ROOT, |
368 | .file_offset = offsetof(struct misc_cg, events_file), |
369 | .seq_show = misc_events_show, |
370 | }, |
371 | {} |
372 | }; |
373 | |
374 | /** |
375 | * misc_cg_alloc() - Allocate misc cgroup. |
376 | * @parent_css: Parent cgroup. |
377 | * |
378 | * Context: Process context. |
379 | * Return: |
380 | * * struct cgroup_subsys_state* - css of the allocated cgroup. |
381 | * * ERR_PTR(-ENOMEM) - No memory available to allocate. |
382 | */ |
383 | static struct cgroup_subsys_state * |
384 | misc_cg_alloc(struct cgroup_subsys_state *parent_css) |
385 | { |
386 | enum misc_res_type i; |
387 | struct misc_cg *cg; |
388 | |
389 | if (!parent_css) { |
390 | cg = &root_cg; |
391 | } else { |
392 | cg = kzalloc(size: sizeof(*cg), GFP_KERNEL); |
393 | if (!cg) |
394 | return ERR_PTR(error: -ENOMEM); |
395 | } |
396 | |
397 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { |
398 | WRITE_ONCE(cg->res[i].max, MAX_NUM); |
399 | atomic64_set(v: &cg->res[i].usage, i: 0); |
400 | } |
401 | |
402 | return &cg->css; |
403 | } |
404 | |
405 | /** |
406 | * misc_cg_free() - Free the misc cgroup. |
407 | * @css: cgroup subsys object. |
408 | * |
409 | * Context: Any context. |
410 | */ |
411 | static void misc_cg_free(struct cgroup_subsys_state *css) |
412 | { |
413 | kfree(objp: css_misc(css)); |
414 | } |
415 | |
416 | /* Cgroup controller callbacks */ |
417 | struct cgroup_subsys misc_cgrp_subsys = { |
418 | .css_alloc = misc_cg_alloc, |
419 | .css_free = misc_cg_free, |
420 | .legacy_cftypes = misc_cg_files, |
421 | .dfl_cftypes = misc_cg_files, |
422 | }; |
423 | |