// SPDX-License-Identifier: GPL-2.0/* * Miscellaneous cgroup controller * * Copyright 2020 Google LLC * Author: Vipin Sharma <vipinsh@google.com> */ #include <linux/limits.h>#include <linux/cgroup.h>#include <linux/errno.h>#include <linux/atomic.h>#include <linux/slab.h>#include <linux/misc_cgroup.h> #define MAX_STR "max"#define MAX_NUM U64_MAX /* Miscellaneous res name, keep it in sync with enum misc_res_type */static const char *const misc_res_name[] = {#ifdef CONFIG_KVM_AMD_SEV	/* AMD SEV ASIDs resource */	"sev",	/* AMD SEV-ES ASIDs resource */	"sev_es",#endif#ifdef CONFIG_INTEL_TDX_HOST	/* Intel TDX HKIDs resource */	"tdx",#endif}; /* Root misc cgroup */static struct misc_cg root_cg; /* * Miscellaneous resources capacity for the entire machine. 0 capacity means * resource is not initialized or not present in the host. * * root_cg.max and capacity are independent of each other. root_cg.max can be * more than the actual capacity. We are using Limits resource distribution * model of cgroup for miscellaneous controller. */static u64 misc_res_capacity[MISC_CG_RES_TYPES]; /** * parent_misc() - Get the parent of the passed misc cgroup. * @cgroup: cgroup whose parent needs to be fetched. * * Context: Any context. * Return: * * struct misc_cg* - Parent of the @cgroup. * * %NULL - If @cgroup is null or the passed cgroup does not have a parent. */static struct misc_cg *parent_misc(struct misc_cg *cgroup){	return cgroup ? css_misc(cgroup->css.parent) : NULL;} /** * valid_type() - Check if @type is valid or not. * @type: misc res type. * * Context: Any context. * Return: * * true - If valid type. * * false - If not valid type. */static inline bool valid_type(enum misc_res_type type){	return type >= 0 && type < MISC_CG_RES_TYPES;} /** * misc_cg_set_capacity() - Set the capacity of the misc cgroup res. * @type: Type of the misc res. * @capacity: Supported capacity of the misc res on the host. * * If capacity is 0 then the charging a misc cgroup fails for that type. * * Context: Any context. * Return: * * %0 - Successfully registered the capacity. * * %-EINVAL - If @type is invalid. */int misc_cg_set_capacity(enum misc_res_type type, u64 capacity){	if (!valid_type(type))		return -EINVAL; 	WRITE_ONCE(misc_res_capacity[type], capacity);	return 0;}EXPORT_SYMBOL_GPL(misc_cg_set_capacity); /** * misc_cg_cancel_charge() - Cancel the charge from the misc cgroup. * @type: Misc res type in misc cg to cancel the charge from. * @cg: Misc cgroup to cancel charge from. * @amount: Amount to cancel. * * Context: Any context. */static void misc_cg_cancel_charge(enum misc_res_type type, struct misc_cg *cg,				  u64 amount){	WARN_ONCE(atomic64_add_negative(-amount, &cg->res[type].usage),		  "misc cgroup resource %s became less than 0",		  misc_res_name[type]);} static void misc_cg_update_watermark(struct misc_res *res, u64 new_usage){	u64 old; 	while (true) {		old = atomic64_read(&res->watermark);		if (new_usage <= old)			break;		if (atomic64_cmpxchg(&res->watermark, old, new_usage) == old)			break;	}} static void misc_cg_event(enum misc_res_type type, struct misc_cg *cg){	atomic64_inc(&cg->res[type].events_local);	cgroup_file_notify(&cg->events_local_file); 	for (; parent_misc(cg); cg = parent_misc(cg)) {		atomic64_inc(&cg->res[type].events);		cgroup_file_notify(&cg->events_file);	}} /** * misc_cg_try_charge() - Try charging the misc cgroup. * @type: Misc res type to charge. * @cg: Misc cgroup which will be charged. * @amount: Amount to charge. * * Charge @amount to the misc cgroup. Caller must use the same cgroup during * the uncharge call. * * Context: Any context. * Return: * * %0 - If successfully charged. * * -EINVAL - If @type is invalid or misc res has 0 capacity. * * -EBUSY - If max limit will be crossed or total usage will be more than the *	      capacity. */int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg, u64 amount){	struct misc_cg *i, *j;	int ret;	struct misc_res *res;	u64 new_usage; 	if (!(valid_type(type) && cg && READ_ONCE(misc_res_capacity[type])))		return -EINVAL; 	if (!amount)		return 0; 	for (i = cg; i; i = parent_misc(i)) {		res = &i->res[type]; 		new_usage = atomic64_add_return(amount, &res->usage);		if (new_usage > READ_ONCE(res->max) ||		    new_usage > READ_ONCE(misc_res_capacity[type])) {			ret = -EBUSY;			goto err_charge;		}		misc_cg_update_watermark(res, new_usage);	}	return 0; err_charge:	misc_cg_event(type, i); 	for (j = cg; j != i; j = parent_misc(j))		misc_cg_cancel_charge(type, j, amount);	misc_cg_cancel_charge(type, i, amount);	return ret;}EXPORT_SYMBOL_GPL(misc_cg_try_charge); /** * misc_cg_uncharge() - Uncharge the misc cgroup. * @type: Misc res type which was charged. * @cg: Misc cgroup which will be uncharged. * @amount: Charged amount. * * Context: Any context. */void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg, u64 amount){	struct misc_cg *i; 	if (!(amount && valid_type(type) && cg))		return; 	for (i = cg; i; i = parent_misc(i))		misc_cg_cancel_charge(type, i, amount);}EXPORT_SYMBOL_GPL(misc_cg_uncharge); /** * misc_cg_max_show() - Show the misc cgroup max limit. * @sf: Interface file * @v: Arguments passed * * Context: Any context. * Return: 0 to denote successful print. */static int misc_cg_max_show(struct seq_file *sf, void *v){	int i;	struct misc_cg *cg = css_misc(seq_css(sf));	u64 max; 	for (i = 0; i < MISC_CG_RES_TYPES; i++) {		if (READ_ONCE(misc_res_capacity[i])) {			max = READ_ONCE(cg->res[i].max);			if (max == MAX_NUM)				seq_printf(sf, "%s max\n", misc_res_name[i]);			else				seq_printf(sf, "%s %llu\n", misc_res_name[i],					   max);		}	} 	return 0;} /** * misc_cg_max_write() - Update the maximum limit of the cgroup. * @of: Handler for the file. * @buf: Data from the user. It should be either "max", 0, or a positive *	 integer. * @nbytes: Number of bytes of the data. * @off: Offset in the file. * * User can pass data like: * echo sev 23 > misc.max, OR * echo sev max > misc.max * * Context: Any context. * Return: * * >= 0 - Number of bytes processed in the input. * * -EINVAL - If buf is not valid. * * -ERANGE - If number is bigger than the u64 capacity. */static ssize_t misc_cg_max_write(struct kernfs_open_file *of, char *buf,				 size_t nbytes, loff_t off){	struct misc_cg *cg;	u64 max;	int ret = 0, i;	enum misc_res_type type = MISC_CG_RES_TYPES;	char *token; 	buf = strstrip(buf);	token = strsep(&buf, " "); 	if (!token || !buf)		return -EINVAL; 	for (i = 0; i < MISC_CG_RES_TYPES; i++) {		if (!strcmp(misc_res_name[i], token)) {			type = i;			break;		}	} 	if (type == MISC_CG_RES_TYPES)		return -EINVAL; 	if (!strcmp(MAX_STR, buf)) {		max = MAX_NUM;	} else {		ret = kstrtou64(buf, 0, &max);		if (ret)			return ret;	} 	cg = css_misc(of_css(of)); 	if (READ_ONCE(misc_res_capacity[type]))		WRITE_ONCE(cg->res[type].max, max);	else		ret = -EINVAL; 	return ret ? ret : nbytes;} /** * misc_cg_current_show() - Show the current usage of the misc cgroup. * @sf: Interface file * @v: Arguments passed * * Context: Any context. * Return: 0 to denote successful print. */static int misc_cg_current_show(struct seq_file *sf, void *v){	int i;	u64 usage;	struct misc_cg *cg = css_misc(seq_css(sf)); 	for (i = 0; i < MISC_CG_RES_TYPES; i++) {		usage = atomic64_read(&cg->res[i].usage);		if (READ_ONCE(misc_res_capacity[i]) || usage)			seq_printf(sf, "%s %llu\n", misc_res_name[i], usage);	} 	return 0;} /** * misc_cg_peak_show() - Show the peak usage of the misc cgroup. * @sf: Interface file * @v: Arguments passed * * Context: Any context. * Return: 0 to denote successful print. */static int misc_cg_peak_show(struct seq_file *sf, void *v){	int i;	u64 watermark;	struct misc_cg *cg = css_misc(seq_css(sf)); 	for (i = 0; i < MISC_CG_RES_TYPES; i++) {		watermark = atomic64_read(&cg->res[i].watermark);		if (READ_ONCE(misc_res_capacity[i]) || watermark)			seq_printf(sf, "%s %llu\n", misc_res_name[i], watermark);	} 	return 0;} /** * misc_cg_capacity_show() - Show the total capacity of misc res on the host. * @sf: Interface file * @v: Arguments passed * * Only present in the root cgroup directory. * * Context: Any context. * Return: 0 to denote successful print. */static int misc_cg_capacity_show(struct seq_file *sf, void *v){	int i;	u64 cap; 	for (i = 0; i < MISC_CG_RES_TYPES; i++) {		cap = READ_ONCE(misc_res_capacity[i]);		if (cap)			seq_printf(sf, "%s %llu\n", misc_res_name[i], cap);	} 	return 0;} static int __misc_events_show(struct seq_file *sf, bool local){	struct misc_cg *cg = css_misc(seq_css(sf));	u64 events;	int i; 	for (i = 0; i < MISC_CG_RES_TYPES; i++) {		if (local)			events = atomic64_read(&cg->res[i].events_local);		else			events = atomic64_read(&cg->res[i].events);		if (READ_ONCE(misc_res_capacity[i]) || events)			seq_printf(sf, "%s.max %llu\n", misc_res_name[i], events);	}	return 0;} static int misc_events_show(struct seq_file *sf, void *v){	return __misc_events_show(sf, false);} static int misc_events_local_show(struct seq_file *sf, void *v){	return __misc_events_show(sf, true);} /* Misc cgroup interface files */static struct cftype misc_cg_files[] = {	{		.name = "max",		.write = misc_cg_max_write,		.seq_show = misc_cg_max_show,		.flags = CFTYPE_NOT_ON_ROOT,	},	{		.name = "current",		.seq_show = misc_cg_current_show,	},	{		.name = "peak",		.seq_show = misc_cg_peak_show,	},	{		.name = "capacity",		.seq_show = misc_cg_capacity_show,		.flags = CFTYPE_ONLY_ON_ROOT,	},	{		.name = "events",		.flags = CFTYPE_NOT_ON_ROOT,		.file_offset = offsetof(struct misc_cg, events_file),		.seq_show = misc_events_show,	},	{		.name = "events.local",		.flags = CFTYPE_NOT_ON_ROOT,		.file_offset = offsetof(struct misc_cg, events_local_file),		.seq_show = misc_events_local_show,	},	{}}; /** * misc_cg_alloc() - Allocate misc cgroup. * @parent_css: Parent cgroup. * * Context: Process context. * Return: * * struct cgroup_subsys_state* - css of the allocated cgroup. * * ERR_PTR(-ENOMEM) - No memory available to allocate. */static struct cgroup_subsys_state *misc_cg_alloc(struct cgroup_subsys_state *parent_css){	enum misc_res_type i;	struct misc_cg *cg; 	if (!parent_css) {		cg = &root_cg;	} else {		cg = kzalloc(sizeof(*cg), GFP_KERNEL);		if (!cg)			return ERR_PTR(-ENOMEM);	} 	for (i = 0; i < MISC_CG_RES_TYPES; i++) {		WRITE_ONCE(cg->res[i].max, MAX_NUM);		atomic64_set(&cg->res[i].usage, 0);	} 	return &cg->css;} /** * misc_cg_free() - Free the misc cgroup. * @css: cgroup subsys object. * * Context: Any context. */static void misc_cg_free(struct cgroup_subsys_state *css){	kfree(css_misc(css));} /* Cgroup controller callbacks */struct cgroup_subsys misc_cgrp_subsys = {	.css_alloc = misc_cg_alloc,	.css_free = misc_cg_free,	.legacy_cftypes = misc_cg_files,	.dfl_cftypes = misc_cg_files,};