[Patch v3 1/2] cgroup: sev: Add misc cgroup controller

Vipin Sharma
2021-03-04T23:20:01Z

The Miscellaneous cgroup provides the resource limiting and tracking
mechanism for the scalar resources which cannot be abstracted like the
other cgroup resources. Controller is enabled by the CONFIG_CGROUP_MISC
config option.

The first two resources added to the miscellaneous controller are Secure
Encrypted Virtualization (SEV) ASIDs and SEV - Encrypted State (SEV-ES)
ASIDs. These limited ASIDs are used for encrypting virtual machines
memory on the AMD platform

Miscellaneous controller provides 3 interface files:

misc.capacity
A read-only flat-keyed file shown only in the root cgroup. It shows
miscellaneous scalar resources available on the platform along with
their quantities::

$ cat misc.capacity
sev 50
sev_es 10

misc.current
A read-only flat-keyed file shown in the non-root cgroups. It shows
the current usage of the resources in the cgroup and its children::

$ cat misc.current
sev 3
sev_es 0

misc.max
A read-write flat-keyed file shown in the non root cgroups. Allowed
maximum usage of the resources in the cgroup and its children.::

$ cat misc.max
sev max
sev_es 4

Limit can be set by::

# echo sev 1 > misc.max

Limit can be set to max by::

# echo sev max > misc.max

Limits can be set more than the capacity value in the misc.capacity
file.

Signed-off-by: Vipin Sharma <vipinsh@google.com>
Reviewed-by: David Rientjes <rientjes@google.com>
---
arch/x86/kvm/svm/sev.c | 65 +++++-
arch/x86/kvm/svm/svm.h | 1 +
include/linux/cgroup_subsys.h | 4 +
include/linux/misc_cgroup.h | 130 +++++++++++
init/Kconfig | 14 ++
kernel/cgroup/Makefile | 1 +
kernel/cgroup/misc.c | 402 ++++++++++++++++++++++++++++++++++
7 files changed, 607 insertions(+), 10 deletions(-)
create mode 100644 include/linux/misc_cgroup.h
create mode 100644 kernel/cgroup/misc.c

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 48017fef1cd9..dd05a1522862 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -14,6 +14,7 @@
#include <linux/psp-sev.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
+#include <linux/misc_cgroup.h>
#include <linux/processor.h>
#include <linux/trace_events.h>
#include <asm/fpu/internal.h>
@@ -27,6 +28,21 @@

#define __ex(x) __kvm_handle_fault_on_reboot(x)

+#ifndef CONFIG_KVM_AMD_SEV
+/*
+ * When this config is not defined, SEV feature is not supported and APIs in
+ * this file are not used but this file still gets compiled into the KVM AMD
+ * module.
+ *
+ * We will not have MISC_CG_RES_SEV and MISC_CG_RES_SEV_ES entries in the enum
+ * misc_res_type {} defined in linux/misc_cgroup.h.
+ *
+ * Below macros allow compilation to succeed.
+ */
+#define MISC_CG_RES_SEV MISC_CG_RES_TYPES
+#define MISC_CG_RES_SEV_ES MISC_CG_RES_TYPES
+#endif
+
static u8 sev_enc_bit;
static int sev_flush_asids(void);
static DECLARE_RWSEM(sev_deactivate_lock);
@@ -88,8 +104,17 @@ static bool __sev_recycle_asids(int min_asid, int max_asid)

static int sev_asid_new(struct kvm_sev_info *sev)
{
- int pos, min_asid, max_asid;
+ int pos, min_asid, max_asid, ret;
bool retry = true;
+ enum misc_res_type type;
+
+ type = sev->es_active ? MISC_CG_RES_SEV_ES : MISC_CG_RES_SEV;
+ sev->misc_cg = get_current_misc_cg();
+ ret = misc_cg_try_charge(type, sev->misc_cg, 1);
+ if (ret) {
+ put_misc_cg(sev->misc_cg);
+ return ret;
+ }

mutex_lock(&sev_bitmap_lock);

@@ -107,7 +132,8 @@ static int sev_asid_new(struct kvm_sev_info *sev)
goto again;
}
mutex_unlock(&sev_bitmap_lock);
- return -EBUSY;
+ ret = -EBUSY;
+ goto e_uncharge;
}

__set_bit(pos, sev_asid_bitmap);
@@ -115,6 +141,10 @@ static int sev_asid_new(struct kvm_sev_info *sev)
mutex_unlock(&sev_bitmap_lock);

return pos + 1;
+e_uncharge:
+ misc_cg_uncharge(type, sev->misc_cg, 1);
+ put_misc_cg(sev->misc_cg);
+ return ret;
}

static int sev_get_asid(struct kvm *kvm)
@@ -124,14 +154,15 @@ static int sev_get_asid(struct kvm *kvm)
return sev->asid;
}

-static void sev_asid_free(int asid)
+static void sev_asid_free(struct kvm_sev_info *sev)
{
struct svm_cpu_data *sd;
int cpu, pos;
+ enum misc_res_type type;

mutex_lock(&sev_bitmap_lock);

- pos = asid - 1;
+ pos = sev->asid - 1;
__set_bit(pos, sev_reclaim_asid_bitmap);

for_each_possible_cpu(cpu) {
@@ -140,6 +171,10 @@ static void sev_asid_free(int asid)
}

mutex_unlock(&sev_bitmap_lock);
+
+ type = sev->es_active ? MISC_CG_RES_SEV_ES : MISC_CG_RES_SEV;
+ misc_cg_uncharge(type, sev->misc_cg, 1);
+ put_misc_cg(sev->misc_cg);
}

static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
@@ -187,19 +222,19 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
asid = sev_asid_new(sev);
if (asid < 0)
return ret;
+ sev->asid = asid;

ret = sev_platform_init(&argp->error);
if (ret)
goto e_free;

sev->active = true;
- sev->asid = asid;
INIT_LIST_HEAD(&sev->regions_list);

return 0;

e_free:
- sev_asid_free(asid);
+ sev_asid_free(sev);
return ret;
}

@@ -1243,12 +1278,12 @@ void sev_vm_destroy(struct kvm *kvm)
mutex_unlock(&kvm->lock);

sev_unbind_asid(kvm, sev->handle);
- sev_asid_free(sev->asid);
+ sev_asid_free(sev);
}

void __init sev_hardware_setup(void)
{
- unsigned int eax, ebx, ecx, edx;
+ unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;
bool sev_es_supported = false;
bool sev_supported = false;

@@ -1280,7 +1315,11 @@ void __init sev_hardware_setup(void)
if (!sev_reclaim_asid_bitmap)
goto out;

- pr_info("SEV supported: %u ASIDs\n", max_sev_asid - min_sev_asid + 1);
+ sev_asid_count = max_sev_asid - min_sev_asid + 1;
+ if (misc_cg_set_capacity(MISC_CG_RES_SEV, sev_asid_count))
+ goto out;
+
+ pr_info("SEV supported: %u ASIDs\n", sev_asid_count);
sev_supported = true;

/* SEV-ES support requested? */
@@ -1295,7 +1334,11 @@ void __init sev_hardware_setup(void)
if (min_sev_asid == 1)
goto out;

- pr_info("SEV-ES supported: %u ASIDs\n", min_sev_asid - 1);
+ sev_es_asid_count = min_sev_asid - 1;
+ if (misc_cg_set_capacity(MISC_CG_RES_SEV_ES, sev_es_asid_count))
+ goto out;
+
+ pr_info("SEV-ES supported: %u ASIDs\n", sev_es_asid_count);
sev_es_supported = true;

out:
@@ -1310,6 +1353,8 @@ void sev_hardware_teardown(void)

bitmap_free(sev_asid_bitmap);
bitmap_free(sev_reclaim_asid_bitmap);
+ misc_cg_set_capacity(MISC_CG_RES_SEV, 0);
+ misc_cg_set_capacity(MISC_CG_RES_SEV_ES, 0);

sev_flush_asids();
}
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 6e7d070f8b86..8ed6ebf47885 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -79,6 +79,7 @@ struct kvm_sev_info {
unsigned long pages_locked; /* Number of pages locked */
struct list_head regions_list; /* List of registered regions */
u64 ap_jump_table; /* SEV-ES AP Jump Table address */
+ struct misc_cg *misc_cg; /* For misc cgroup accounting */
};

struct kvm_svm {
diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index acb77dcff3b4..445235487230 100644
--- a/include/linux/cgroup_subsys.h
+++ b/include/linux/cgroup_subsys.h
@@ -61,6 +61,10 @@ SUBSYS(pids)
SUBSYS(rdma)
#endif

+#if IS_ENABLED(CONFIG_CGROUP_MISC)
+SUBSYS(misc)
+#endif
+
/*
* The following subsystems are not supported on the default hierarchy.
*/
diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
new file mode 100644
index 000000000000..c807840c9238
--- /dev/null
+++ b/include/linux/misc_cgroup.h
@@ -0,0 +1,130 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Miscellaneous cgroup controller.
+ *
+ * Copyright 2020 Google LLC
+ * Author: Vipin Sharma <vipinsh@google.com>
+ */
+#ifndef _MISC_CGROUP_H_
+#define _MISC_CGROUP_H_
+
+/**
+ * Types of misc cgroup entries supported by the host.
+ */
+enum misc_res_type {
+#ifdef CONFIG_KVM_AMD_SEV
+ /* AMD SEV ASIDs resource */
+ MISC_CG_RES_SEV,
+ /* AMD SEV-ES ASIDs resource */
+ MISC_CG_RES_SEV_ES,
+#endif
+ MISC_CG_RES_TYPES
+};
+
+struct misc_cg;
+
+#ifdef CONFIG_CGROUP_MISC
+
+/**
+ * struct misc_res: Per cgroup per misc type resource
+ * @max: Maximum limit on the resource.
+ * @usage: Current usage of the resource.
+ * @failed: True if charged failed for the resource in a cgroup.
+ */
+struct misc_res {
+ unsigned long max;
+ atomic_long_t usage;
+ bool failed;
+};
+
+/**
+ * struct misc_cg - Miscellaneous controller's cgroup structure.
+ * @css: cgroup subsys state object.
+ * @res: Array of misc resources usage in the cgroup.
+ */
+struct misc_cg {
+ struct cgroup_subsys_state css;
+ struct misc_res res[MISC_CG_RES_TYPES];
+};
+
+unsigned long misc_cg_res_total_usage(enum misc_res_type type);
+int misc_cg_set_capacity(enum misc_res_type type, unsigned long capacity);
+int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
+ unsigned long amount);
+void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg,
+ unsigned long amount);
+
+/**
+ * css_misc() - Get misc cgroup from the css.
+ * @css: cgroup subsys state object.
+ *
+ * Context: Any context.
+ * Return:
+ * * %NULL - If @css is null.
+ * * struct misc_cg* - misc cgroup pointer of the passed css.
+ */
+static inline struct misc_cg *css_misc(struct cgroup_subsys_state *css)
+{
+ return css ? container_of(css, struct misc_cg, css) : NULL;
+}
+
+/*
+ * get_current_misc_cg() - Find and get the misc cgroup of the current task.
+ *
+ * Returned cgroup has its ref count increased by 1. Caller must call
+ * put_misc_cg() to return the reference.
+ *
+ * Return: Misc cgroup to which the current task belongs to.
+ */
+static inline struct misc_cg *get_current_misc_cg(void)
+{
+ return css_misc(task_get_css(current, misc_cgrp_id));
+}
+
+/*
+ * put_misc_cg() - Put the misc cgroup and reduce its ref count.
+ * @cg - cgroup to put.
+ */
+static inline void put_misc_cg(struct misc_cg *cg)
+{
+ if (cg)
+ css_put(&cg->css);
+}
+
+#else /* !CONFIG_CGROUP_MISC */
+
+unsigned long misc_cg_res_total_usage(enum misc_res_type type)
+{
+ return 0;
+}
+
+static inline int misc_cg_set_capacity(enum misc_res_type type,
+ unsigned long capacity)
+{
+ return 0;
+}
+
+static inline int misc_cg_try_charge(enum misc_res_type type,
+ struct misc_cg *cg,
+ unsigned long amount)
+{
+ return 0;
+}
+
+static inline void misc_cg_uncharge(enum misc_res_type type,
+ struct misc_cg *cg,
+ unsigned long amount)
+{
+}
+
+static inline struct misc_cg *get_current_misc_cg(void)
+{
+ return NULL;
+}
+
+static inline void put_misc_cg(struct misc_cg *cg)
+{
+}
+
+#endif /* CONFIG_CGROUP_MISC */
+#endif /* _MISC_CGROUP_H_ */
diff --git a/init/Kconfig b/init/Kconfig
index 29ad68325028..0b392135e555 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1105,6 +1105,20 @@ config CGROUP_BPF
BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
inet sockets.

+config CGROUP_MISC
+ bool "Misc resource controller"
+ default n
+ help
+ Provides a controller for miscellaneous resources on a host.
+
+ Miscellaneous scalar resources are the resources on the host system
+ which cannot be abstracted like the other cgroups. This controller
+ tracks and limits the miscellaneous resources used by a process
+ attached to a cgroup hierarchy.
+
+ For more information, please check misc cgroup section in
+ /Documentation/admin-guide/cgroup-v2.rst.
+
config CGROUP_DEBUG
bool "Debug controller"
default n
diff --git a/kernel/cgroup/Makefile b/kernel/cgroup/Makefile
index 5d7a76bfbbb7..12f8457ad1f9 100644
--- a/kernel/cgroup/Makefile
+++ b/kernel/cgroup/Makefile
@@ -5,4 +5,5 @@ obj-$(CONFIG_CGROUP_FREEZER) += legacy_freezer.o
obj-$(CONFIG_CGROUP_PIDS) += pids.o
obj-$(CONFIG_CGROUP_RDMA) += rdma.o
obj-$(CONFIG_CPUSETS) += cpuset.o
+obj-$(CONFIG_CGROUP_MISC) += misc.o
obj-$(CONFIG_CGROUP_DEBUG) += debug.o
diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
new file mode 100644
index 000000000000..393d66c0b933
--- /dev/null
+++ b/kernel/cgroup/misc.c
@@ -0,0 +1,402 @@
+// 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 ULONG_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
+ "sev",
+ "sev_es",
+#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 unsigned long 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_res_total_usage() - Get the current total usage of the resource.
+ * @type: misc res type.
+ *
+ * Context: Any context.
+ * Return: Current total usage of the resource.
+ */
+unsigned long misc_cg_res_total_usage(enum misc_res_type type)
+{
+ if (valid_type(type))
+ return atomic_long_read(&root_cg.res[type].usage);
+
+ return 0;
+}
+EXPORT_SYMBOL(misc_cg_res_total_usage);
+
+/**
+ * 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, unsigned long capacity)
+{
+ if (!valid_type(type))
+ return -EINVAL;
+
+ misc_res_capacity[type] = capacity;
+ return 0;
+}
+EXPORT_SYMBOL(misc_cg_set_capacity);
+
+/**
+ * misc_cg_reduce_charge() - Reduce the charge from the misc cgroup.
+ * @type: Misc res type in misc cg to reduce the charge from.
+ * @cg: Misc cgroup to reduce charge from.
+ * @amount: Amount to reduce.
+ *
+ * Context: Any context.
+ */
+static void misc_cg_reduce_charge(enum misc_res_type type, struct misc_cg *cg,
+ unsigned long amount)
+{
+ WARN_ONCE(atomic_long_add_negative(-amount, &cg->res[type].usage),
+ "misc cgroup resource %s became less than 0",
+ misc_res_name[type]);
+}
+
+/**
+ * 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,
+ unsigned long amount)
+{
+ struct misc_cg *i, *j;
+ int ret;
+ struct misc_res *res;
+ int new_usage;
+
+ if (!(valid_type(type) && cg && misc_res_capacity[type]))
+ return -EINVAL;
+
+ if (!amount)
+ return 0;
+
+ for (i = cg; i; i = parent_misc(i)) {
+ res = &i->res[type];
+
+ new_usage = atomic_long_add_return(amount, &res->usage);
+ if (new_usage > res->max ||
+ new_usage > misc_res_capacity[type]) {
+ if (!res->failed) {
+ pr_info("cgroup: charge rejected by the misc controller for %s resource in ",
+ misc_res_name[type]);
+ pr_cont_cgroup_path(i->css.cgroup);
+ pr_cont("\n");
+ res->failed = true;
+ }
+ ret = -EBUSY;
+ goto err_charge;
+ }
+ }
+ return 0;
+
+err_charge:
+ for (j = cg; j != i; j = parent_misc(j))
+ misc_cg_reduce_charge(type, j, amount);
+ misc_cg_reduce_charge(type, i, amount);
+ return ret;
+}
+EXPORT_SYMBOL(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,
+ unsigned long amount)
+{
+ struct misc_cg *i;
+
+ if (!(amount && valid_type(type) && cg))
+ return;
+
+ for (i = cg; i; i = parent_misc(i))
+ misc_cg_reduce_charge(type, i, amount);
+}
+EXPORT_SYMBOL(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));
+
+ for (i = 0; i < MISC_CG_RES_TYPES; i++) {
+ if (misc_res_capacity[i]) {
+ if (cg->res[i].max == MAX_NUM)
+ seq_printf(sf, "%s max\n", misc_res_name[i]);
+ else
+ seq_printf(sf, "%s %lu\n", misc_res_name[i],
+ cg->res[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 unsigned long 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;
+ unsigned long 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 = ULONG_MAX;
+ } else {
+ ret = kstrtoul(buf, 0, &max);
+ if (ret)
+ return ret;
+ }
+
+ cg = css_misc(of_css(of));
+
+ if (misc_res_capacity[type])
+ 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;
+ struct misc_cg *cg = css_misc(seq_css(sf));
+
+ for (i = 0; i < MISC_CG_RES_TYPES; i++) {
+ if (misc_res_capacity[i])
+ seq_printf(sf, "%s %lu\n", misc_res_name[i],
+ atomic_long_read(&cg->res[i].usage));
+ }
+
+ 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;
+ unsigned long cap;
+
+ for (i = 0; i < MISC_CG_RES_TYPES; i++) {
+ cap = READ_ONCE(misc_res_capacity[i]);
+ if (cap)
+ seq_printf(sf, "%s %lu\n", misc_res_name[i], cap);
+ }
+
+ return 0;
+}
+
+/* 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,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+ {
+ .name = "capacity",
+ .seq_show = misc_cg_capacity_show,
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ },
+ {}
+};
+
+/**
+ * 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++) {
+ cg->res[i].max = MAX_NUM;
+ atomic_long_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,
+};
--
2.30.1.766.gb4fecdf3b7-goog