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Commit 4e978d06 authored by Fenghua Yu's avatar Fenghua Yu Committed by Thomas Gleixner
Browse files

x86/intel_rdt: Add "info" files to resctrl file system 



For the convenience of applications we make the decoded values of some
of the CPUID values available in read-only (0444) files.

Signed-off-by: default avatarFenghua Yu <fenghua.yu@intel.com>
Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com>
Cc: "Tony Luck" <tony.luck@intel.com>
Cc: "Shaohua Li" <shli@fb.com>
Cc: "Sai Prakhya" <sai.praneeth.prakhya@intel.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>
Cc: "Stephane Eranian" <eranian@google.com>
Cc: "Dave Hansen" <dave.hansen@intel.com>
Cc: "David Carrillo-Cisneros" <davidcc@google.com>
Cc: "Nilay Vaish" <nilayvaish@gmail.com>
Cc: "Vikas Shivappa" <vikas.shivappa@linux.intel.com>
Cc: "Ingo Molnar" <mingo@elte.hu>
Cc: "Borislav Petkov" <bp@suse.de>
Cc: "H. Peter Anvin" <h.peter.anvin@intel.com>
Link: http://lkml.kernel.org/r/1477692289-37412-5-git-send-email-fenghua.yu@intel.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 5ff193fb

arch/x86/include/asm/intel_rdt.h

+24 −0
Original line number Diff line number Diff line
@@ -26,6 +26,30 @@ extern struct list_head rdt_all_groups; 


int __init rdtgroup_init(void);



/**

 * struct rftype - describe each file in the resctrl file system

 * @name: file name

 * @mode: access mode

 * @kf_ops: operations

 * @seq_show: show content of the file

 * @write: write to the file

 */

struct rftype {

	char			*name;

	umode_t			mode;

	struct kernfs_ops	*kf_ops;



	int (*seq_show)(struct kernfs_open_file *of,

			struct seq_file *sf, void *v);

	/*

	 * write() is the generic write callback which maps directly to

	 * kernfs write operation and overrides all other operations.

	 * Maximum write size is determined by ->max_write_len.

	 */

	ssize_t (*write)(struct kernfs_open_file *of,

			 char *buf, size_t nbytes, loff_t off);

};



/**

 * struct rdt_resource - attributes of an RDT resource

 * @enabled:			Is this feature enabled on this machine

arch/x86/kernel/cpu/intel_rdt_rdtgroup.c

+185 −0
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ 
#include <linux/fs.h>

#include <linux/sysfs.h>

#include <linux/kernfs.h>

#include <linux/seq_file.h>

#include <linux/sched.h>

#include <linux/slab.h>



#include <uapi/linux/magic.h>
@@ -34,6 +36,176 @@ struct kernfs_root *rdt_root; 
struct rdtgroup rdtgroup_default;

LIST_HEAD(rdt_all_groups);



/* Kernel fs node for "info" directory under root */

static struct kernfs_node *kn_info;



/* set uid and gid of rdtgroup dirs and files to that of the creator */

static int rdtgroup_kn_set_ugid(struct kernfs_node *kn)

{

	struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,

				.ia_uid = current_fsuid(),

				.ia_gid = current_fsgid(), };



	if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&

	    gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))

		return 0;



	return kernfs_setattr(kn, &iattr);

}



static int rdtgroup_add_file(struct kernfs_node *parent_kn, struct rftype *rft)

{

	struct kernfs_node *kn;

	int ret;



	kn = __kernfs_create_file(parent_kn, rft->name, rft->mode,

				  0, rft->kf_ops, rft, NULL, NULL);

	if (IS_ERR(kn))

		return PTR_ERR(kn);



	ret = rdtgroup_kn_set_ugid(kn);

	if (ret) {

		kernfs_remove(kn);

		return ret;

	}



	return 0;

}



static int rdtgroup_add_files(struct kernfs_node *kn, struct rftype *rfts,

			      int len)

{

	struct rftype *rft;

	int ret;



	lockdep_assert_held(&rdtgroup_mutex);



	for (rft = rfts; rft < rfts + len; rft++) {

		ret = rdtgroup_add_file(kn, rft);

		if (ret)

			goto error;

	}



	return 0;

error:

	pr_warn("Failed to add %s, err=%d\n", rft->name, ret);

	while (--rft >= rfts)

		kernfs_remove_by_name(kn, rft->name);

	return ret;

}



static int rdtgroup_seqfile_show(struct seq_file *m, void *arg)

{

	struct kernfs_open_file *of = m->private;

	struct rftype *rft = of->kn->priv;



	if (rft->seq_show)

		return rft->seq_show(of, m, arg);

	return 0;

}



static ssize_t rdtgroup_file_write(struct kernfs_open_file *of, char *buf,

				   size_t nbytes, loff_t off)

{

	struct rftype *rft = of->kn->priv;



	if (rft->write)

		return rft->write(of, buf, nbytes, off);



	return -EINVAL;

}



static struct kernfs_ops rdtgroup_kf_single_ops = {

	.atomic_write_len	= PAGE_SIZE,

	.write			= rdtgroup_file_write,

	.seq_show		= rdtgroup_seqfile_show,

};



static int rdt_num_closids_show(struct kernfs_open_file *of,

				struct seq_file *seq, void *v)

{

	struct rdt_resource *r = of->kn->parent->priv;



	seq_printf(seq, "%d\n", r->num_closid);



	return 0;

}



static int rdt_cbm_mask_show(struct kernfs_open_file *of,

			     struct seq_file *seq, void *v)

{

	struct rdt_resource *r = of->kn->parent->priv;



	seq_printf(seq, "%x\n", r->max_cbm);



	return 0;

}



/* rdtgroup information files for one cache resource. */

static struct rftype res_info_files[] = {

	{

		.name		= "num_closids",

		.mode		= 0444,

		.kf_ops		= &rdtgroup_kf_single_ops,

		.seq_show	= rdt_num_closids_show,

	},

	{

		.name		= "cbm_mask",

		.mode		= 0444,

		.kf_ops		= &rdtgroup_kf_single_ops,

		.seq_show	= rdt_cbm_mask_show,

	},

};



static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)

{

	struct kernfs_node *kn_subdir;

	struct rdt_resource *r;

	int ret;



	/* create the directory */

	kn_info = kernfs_create_dir(parent_kn, "info", parent_kn->mode, NULL);

	if (IS_ERR(kn_info))

		return PTR_ERR(kn_info);

	kernfs_get(kn_info);



	for_each_enabled_rdt_resource(r) {

		kn_subdir = kernfs_create_dir(kn_info, r->name,

					      kn_info->mode, r);

		if (IS_ERR(kn_subdir)) {

			ret = PTR_ERR(kn_subdir);

			goto out_destroy;

		}

		kernfs_get(kn_subdir);

		ret = rdtgroup_kn_set_ugid(kn_subdir);

		if (ret)

			goto out_destroy;

		ret = rdtgroup_add_files(kn_subdir, res_info_files,

					 ARRAY_SIZE(res_info_files));

		if (ret)

			goto out_destroy;

		kernfs_activate(kn_subdir);

	}



	/*

	 * This extra ref will be put in kernfs_remove() and guarantees

	 * that @rdtgrp->kn is always accessible.

	 */

	kernfs_get(kn_info);



	ret = rdtgroup_kn_set_ugid(kn_info);

	if (ret)

		goto out_destroy;



	kernfs_activate(kn_info);



	return 0;



out_destroy:

	kernfs_remove(kn_info);

	return ret;

}



static void l3_qos_cfg_update(void *arg)

{

	bool *enable = arg;
@@ -137,6 +309,10 @@ static struct dentry *rdt_mount(struct file_system_type *fs_type, 
		goto out_cdp;

	}



	ret = rdtgroup_create_info_dir(rdtgroup_default.kn);

	if (ret)

		goto out_cdp;



	dentry = kernfs_mount(fs_type, flags, rdt_root,

			      RDTGROUP_SUPER_MAGIC, NULL);

	if (IS_ERR(dentry))
@@ -191,6 +367,14 @@ static int reset_all_cbms(struct rdt_resource *r) 
	return 0;

}



/*

 * Forcibly remove all of subdirectories under root.

 */

static void rmdir_all_sub(void)

{

	kernfs_remove(kn_info);

}



static void rdt_kill_sb(struct super_block *sb)

{

	struct rdt_resource *r;
@@ -201,6 +385,7 @@ static void rdt_kill_sb(struct super_block *sb) 
	for_each_enabled_rdt_resource(r)

		reset_all_cbms(r);

	cdp_disable();

	rmdir_all_sub();

	static_branch_disable(&rdt_enable_key);

	kernfs_kill_sb(sb);

	mutex_unlock(&rdtgroup_mutex);