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Subject[PATCH v4 11/18] x86/intel_rdt: Add basic resctrl filesystem support
Date
From: Fenghua Yu <fenghua.yu@intel.com>

Use kernfs as basis for our user interface filesystem. This patch
supports mount/umount, and one mount parameter "cdp" to enable code/data
prioritization (though all we do at this point is ensure that the system
can support CDP). The file system is not populated yet in this patch.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/include/asm/intel_rdt.h | 22 +++
arch/x86/kernel/cpu/Makefile | 2 +-
arch/x86/kernel/cpu/intel_rdt.c | 8 +-
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 235 +++++++++++++++++++++++++++++++
include/uapi/linux/magic.h | 1 +
5 files changed, 266 insertions(+), 2 deletions(-)
create mode 100644 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c

diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
index b3df691..f7acae2 100644
--- a/arch/x86/include/asm/intel_rdt.h
+++ b/arch/x86/include/asm/intel_rdt.h
@@ -5,6 +5,23 @@
#define IA32_L2_CBM_BASE 0xd10

/**
+ * struct rdtgroup - store rdtgroup's data in resctrl file system.
+ * @kn: kernfs node
+ * @rdtgroup_list: linked list for all rdtgroups
+ * @closid: closid for this rdtgroup
+ */
+struct rdtgroup {
+ struct kernfs_node *kn;
+ struct list_head rdtgroup_list;
+ int closid;
+};
+
+/* List of all resource groups */
+extern struct list_head rdt_all_groups;
+
+int __init rdtgroup_init(void);
+
+/**
* struct rdt_resource - attributes of an RDT resource
* @enabled: Is this feature enabled on this machine
* @name: Name to use in "schemata" file
@@ -42,6 +59,7 @@ struct rdt_resource {
for (r = rdt_resources_all; r->name; r++) \
if (r->enabled)

+#define IA32_L3_QOS_CFG 0xc81
#define IA32_L3_CBM_BASE 0xc90

/**
@@ -73,6 +91,10 @@ struct msr_param {
extern struct mutex rdtgroup_mutex;

extern struct rdt_resource rdt_resources_all[];
+extern struct rdtgroup rdtgroup_default;
+extern struct static_key_false rdt_enable_key;
+
+int __init rdtgroup_init(void);

enum {
RDT_RESOURCE_L3,
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index cf4bfd0..b4334e8 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -34,7 +34,7 @@ obj-$(CONFIG_CPU_SUP_CENTAUR) += centaur.o
obj-$(CONFIG_CPU_SUP_TRANSMETA_32) += transmeta.o
obj-$(CONFIG_CPU_SUP_UMC_32) += umc.o

-obj-$(CONFIG_INTEL_RDT_A) += intel_rdt.o
+obj-$(CONFIG_INTEL_RDT_A) += intel_rdt.o intel_rdt_rdtgroup.o

obj-$(CONFIG_X86_MCE) += mcheck/
obj-$(CONFIG_MTRR) += mtrr/
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 0b47ea9..3d4a125 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -266,7 +266,7 @@ static int intel_rdt_offline_cpu(unsigned int cpu)
static int __init intel_rdt_late_init(void)
{
struct rdt_resource *r;
- int state;
+ int state, ret;

if (!get_rdt_resources())
return -ENODEV;
@@ -277,6 +277,12 @@ static int __init intel_rdt_late_init(void)
if (state < 0)
return state;

+ ret = rdtgroup_init();
+ if (ret) {
+ cpuhp_remove_state(state);
+ return ret;
+ }
+
for_each_rdt_resource(r)
pr_info("Intel RDT %s allocation %s detected\n", r->name,
r->cdp_capable ? " (with CDP)" : "");
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
new file mode 100644
index 0000000..b2bbd04
--- /dev/null
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -0,0 +1,235 @@
+/*
+ * User interface for Resource Alloction in Resource Director Technology(RDT)
+ *
+ * Copyright (C) 2016 Intel Corporation
+ *
+ * Author: Fenghua Yu <fenghua.yu@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * More information about RDT be found in the Intel (R) x86 Architecture
+ * Software Developer Manual.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/fs.h>
+#include <linux/sysfs.h>
+#include <linux/kernfs.h>
+#include <linux/slab.h>
+
+#include <uapi/linux/magic.h>
+
+#include <asm/intel_rdt.h>
+
+DEFINE_STATIC_KEY_FALSE(rdt_enable_key);
+struct kernfs_root *rdt_root;
+struct rdtgroup rdtgroup_default;
+LIST_HEAD(rdt_all_groups);
+
+static void l3_qos_cfg_update(void *arg)
+{
+ struct rdt_resource *r = arg;
+
+ wrmsrl(IA32_L3_QOS_CFG, r->cdp_enabled);
+}
+
+static void set_l3_qos_cfg(struct rdt_resource *r)
+{
+ struct list_head *l;
+ struct rdt_domain *d;
+ struct cpumask cpu_mask;
+ int cpu;
+
+ cpumask_clear(&cpu_mask);
+ list_for_each(l, &r->domains) {
+ d = list_entry(l, struct rdt_domain, list);
+ cpumask_set_cpu(cpumask_any(&d->cpu_mask), &cpu_mask);
+ }
+ cpu = get_cpu();
+ /* Update QOS_CFG MSR on this cpu if it's in cpu_mask. */
+ if (cpumask_test_cpu(cpu, &cpu_mask))
+ l3_qos_cfg_update(r);
+ /* Update QOS_CFG MSR on all other cpus in cpu_mask. */
+ smp_call_function_many(&cpu_mask, l3_qos_cfg_update, r, 1);
+ put_cpu();
+}
+
+static int parse_rdtgroupfs_options(char *data)
+{
+ char *token, *o = data;
+ struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3];
+
+ r->cdp_enabled = false;
+ while ((token = strsep(&o, ",")) != NULL) {
+ if (!*token)
+ return -EINVAL;
+
+ if (!strcmp(token, "cdp"))
+ if (r->enabled && r->cdp_capable)
+ r->cdp_enabled = true;
+ }
+
+ return 0;
+}
+
+static struct dentry *rdt_mount(struct file_system_type *fs_type,
+ int flags, const char *unused_dev_name,
+ void *data)
+{
+ struct dentry *dentry;
+ int ret;
+ bool new_sb;
+
+ mutex_lock(&rdtgroup_mutex);
+ /*
+ * resctrl file system can only be mounted once.
+ */
+ if (static_branch_unlikely(&rdt_enable_key)) {
+ dentry = ERR_PTR(-EBUSY);
+ goto out;
+ }
+
+ ret = parse_rdtgroupfs_options(data);
+ if (ret) {
+ dentry = ERR_PTR(ret);
+ goto out;
+ }
+
+ dentry = kernfs_mount(fs_type, flags, rdt_root,
+ RDTGROUP_SUPER_MAGIC, &new_sb);
+ if (IS_ERR(dentry))
+ goto out;
+ if (!new_sb) {
+ dentry = ERR_PTR(-EINVAL);
+ goto out;
+ }
+ if (rdt_resources_all[RDT_RESOURCE_L3].cdp_capable)
+ set_l3_qos_cfg(&rdt_resources_all[RDT_RESOURCE_L3]);
+ static_branch_enable(&rdt_enable_key);
+
+out:
+ mutex_unlock(&rdtgroup_mutex);
+
+ return dentry;
+}
+
+static void reset_all_cbms(struct rdt_resource *r)
+{
+ struct list_head *l;
+ struct rdt_domain *d;
+ struct msr_param msr_param;
+ struct cpumask cpu_mask;
+ int i, cpu;
+
+ cpumask_clear(&cpu_mask);
+ msr_param.res = r;
+ msr_param.low = 0;
+ msr_param.high = r->max_closid;
+
+ list_for_each(l, &r->domains) {
+ d = list_entry(l, struct rdt_domain, list);
+ cpumask_set_cpu(cpumask_any(&d->cpu_mask), &cpu_mask);
+
+ for (i = 0; i < r->max_closid; i++)
+ d->cbm[i] = r->max_cbm;
+ }
+ cpu = get_cpu();
+ /* Update CBM on this cpu if it's in cpu_mask. */
+ if (cpumask_test_cpu(cpu, &cpu_mask))
+ rdt_cbm_update(&msr_param);
+ /* Updte CBM on all other cpus in cpu_mask. */
+ smp_call_function_many(&cpu_mask, rdt_cbm_update, &msr_param, 1);
+ put_cpu();
+}
+
+static void rdt_kill_sb(struct super_block *sb)
+{
+ struct rdt_resource *r;
+
+ mutex_lock(&rdtgroup_mutex);
+
+ /*Put everything back to default values. */
+ for_each_rdt_resource(r)
+ reset_all_cbms(r);
+ r = &rdt_resources_all[RDT_RESOURCE_L3];
+ if (r->cdp_capable) {
+ r->cdp_enabled = 0;
+ set_l3_qos_cfg(r);
+ }
+
+ static_branch_disable(&rdt_enable_key);
+ kernfs_kill_sb(sb);
+ mutex_unlock(&rdtgroup_mutex);
+}
+
+static struct file_system_type rdt_fs_type = {
+ .name = "resctrl",
+ .mount = rdt_mount,
+ .kill_sb = rdt_kill_sb,
+};
+
+static struct kernfs_syscall_ops rdtgroup_kf_syscall_ops = {
+};
+
+static int __init rdtgroup_setup_root(void)
+{
+ rdt_root = kernfs_create_root(&rdtgroup_kf_syscall_ops,
+ KERNFS_ROOT_CREATE_DEACTIVATED,
+ &rdtgroup_default);
+ if (IS_ERR(rdt_root))
+ return PTR_ERR(rdt_root);
+
+ mutex_lock(&rdtgroup_mutex);
+
+ rdtgroup_default.closid = 0;
+ list_add(&rdtgroup_default.rdtgroup_list, &rdt_all_groups);
+
+ rdtgroup_default.kn = rdt_root->kn;
+ kernfs_activate(rdtgroup_default.kn);
+
+ mutex_unlock(&rdtgroup_mutex);
+
+ return 0;
+}
+
+/*
+ * rdtgroup_init - rdtgroup initialization
+ *
+ * Setup resctrl file system including set up root, create mount point,
+ * register rdtgroup filesystem, and initialize files under root directory.
+ *
+ * Return: 0 on success or -errno
+ */
+int __init rdtgroup_init(void)
+{
+ int ret = 0;
+
+ ret = rdtgroup_setup_root();
+ if (ret)
+ return ret;
+
+ ret = sysfs_create_mount_point(fs_kobj, "resctrl");
+ if (ret)
+ goto cleanup_root;
+
+ ret = register_filesystem(&rdt_fs_type);
+ if (ret)
+ goto cleanup_mountpoint;
+
+ return 0;
+
+cleanup_mountpoint:
+ sysfs_remove_mount_point(fs_kobj, "resctrl");
+cleanup_root:
+ kernfs_destroy_root(rdt_root);
+
+ return ret;
+}
diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
index e398bea..27ef03d 100644
--- a/include/uapi/linux/magic.h
+++ b/include/uapi/linux/magic.h
@@ -57,6 +57,7 @@
#define CGROUP_SUPER_MAGIC 0x27e0eb
#define CGROUP2_SUPER_MAGIC 0x63677270

+#define RDTGROUP_SUPER_MAGIC 0x7655821

#define STACK_END_MAGIC 0x57AC6E9D

--
2.5.0
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