[PATCH v3 16/18] x86/intel_rdt: Add schemata file

[Fenghua Yu]

From: Tony Luck <tony.luck@xxxxxxxxx>

Last of the per resource group files. Also mode 0644. This one shows
the resources available to the group. Syntax depends on whether the
"cdp" mount option was given. With code/data prioritization disabled
it is simply a list of masks for each cache domain. Initial value
allows access to all of the L3 cache on all domains. E.g. on a 2 socket
Broadwell:
        L3:0=fffff;1=fffff
With CDP enabled, separate masks for data and instructions are provided:
        L3:0=fffff,fffff;1=fffff,fffff

Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
---
 arch/x86/include/asm/intel_rdt.h         |   6 +
 arch/x86/kernel/cpu/Makefile             |   2 +-
 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c |   7 +
 arch/x86/kernel/cpu/intel_rdt_schemata.c | 260 +++++++++++++++++++++++++++++++
 4 files changed, 274 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/kernel/cpu/intel_rdt_schemata.c

diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
index 7c74272..c052652 100644
--- a/arch/x86/include/asm/intel_rdt.h
+++ b/arch/x86/include/asm/intel_rdt.h
@@ -67,6 +67,7 @@ struct rftype {
  * @cdp_capable:		Code/Data Prioritization available
  * @cdp_enabled:		Code/Data Prioritization enabled
  * @tmp_cbms:			Scratch space when updating schemata
+ * @num_cbms:			Number of CBMs in tmp_cbms
  * @cache_level:		Which cache level defines scope of this domain
  */
 struct rdt_resource {
@@ -83,6 +84,7 @@ struct rdt_resource {
 	bool			cdp_capable;
 	bool			cdp_enabled;
 	u32			*tmp_cbms;
+	int			num_cbms;
 	int			cache_level;
 };
 
@@ -155,4 +157,8 @@ DECLARE_PER_CPU_READ_MOSTLY(int, cpu_closid);
 void rdt_cbm_update(void *arg);
 struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn);
 void rdtgroup_kn_unlock(struct kernfs_node *kn);
+ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off);
+int rdtgroup_schemata_show(struct kernfs_open_file *of,
+			   struct seq_file *s, void *v);
 #endif /* _ASM_X86_INTEL_RDT_H */
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 963c54a..4d7e0e5 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-$(CONFIG_INTEL_RDT)	+= intel_rdt.o intel_rdt_rdtgroup.o
+obj-$(CONFIG_INTEL_RDT)	+= intel_rdt.o intel_rdt_rdtgroup.o intel_rdt_schemata.o
 
 obj-$(CONFIG_X86_MCE)			+= mcheck/
 obj-$(CONFIG_MTRR)			+= mtrr/
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index e9e834b..4740b7e 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -425,6 +425,13 @@ static struct rftype rdtgroup_base_files[] = {
 		.seq_show	= rdtgroup_tasks_show,
 	},
 	{
+		.name		= "schemata",
+		.mode		= 0644,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.write		= rdtgroup_schemata_write,
+		.seq_show	= rdtgroup_schemata_show,
+	},
+	{
 		/* NULL terminated */
 	}
 };
diff --git a/arch/x86/kernel/cpu/intel_rdt_schemata.c b/arch/x86/kernel/cpu/intel_rdt_schemata.c
new file mode 100644
index 0000000..d666854
--- /dev/null
+++ b/arch/x86/kernel/cpu/intel_rdt_schemata.c
@@ -0,0 +1,260 @@
+/*
+ * Resource Director Technology(RDT)
+ * - Cache Allocation code.
+ *
+ * Copyright (C) 2016 Intel Corporation
+ *
+ * Authors:
+ *    Fenghua Yu <fenghua.yu@xxxxxxxxx>
+ *    Tony Luck <tony.luck@xxxxxxxxx>
+ *
+ * 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 June 2016, volume 3, section 17.17.
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/kernfs.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <asm/intel_rdt.h>
+
+/*
+ * Check whether a cache bit mask is valid. The SDM says:
+ *	Please note that all (and only) contiguous '1' combinations
+ *	are allowed (e.g. FFFFH, 0FF0H, 003CH, etc.).
+ * Additionally Haswell requires at least two bits set.
+ */
+static bool cbm_validate(unsigned long var, struct rdt_resource *r)
+{
+	unsigned long first_bit, zero_bit;
+
+	if (var == 0 || var > r->max_cbm)
+		return false;
+
+	first_bit = find_first_bit(&var, r->cbm_len);
+	zero_bit = find_next_zero_bit(&var, r->cbm_len, first_bit);
+
+	if (find_next_bit(&var, r->cbm_len, zero_bit) < r->cbm_len)
+		return false;
+
+	if ((zero_bit - first_bit) < r->min_cbm_bits)
+		return false;
+	return true;
+}
+
+/*
+ * Read one cache bit mask (hex). Check that it is valid for the current
+ * resource type.
+ */
+static int parse_cbm_token(char *tok, struct rdt_resource *r)
+{
+	unsigned long data;
+	int ret;
+
+	ret = kstrtoul(tok, 16, &data);
+	if (ret)
+		return ret;
+	if (!cbm_validate(data, r))
+		return -EINVAL;
+	r->tmp_cbms[r->num_cbms++] = data;
+	return 0;
+}
+
+/*
+ * If code/data prioritization is enabled for this resource we need
+ * two bit masks separated by a ",". Otherwise a single bit mask.
+ */
+static int parse_cbm(char *buf, struct rdt_resource *r)
+{
+	char *cbm1 = buf;
+	int ret;
+
+	if (r->cdp_enabled)
+		cbm1 = strsep(&buf, ",");
+	if (!cbm1 || !buf)
+		return 1;
+	ret = parse_cbm_token(cbm1, r);
+	if (ret)
+		return ret;
+	if (r->cdp_enabled)
+		return parse_cbm_token(buf, r);
+	return 0;
+}
+
+/*
+ * For each domain in this resource we expect to find a series of:
+ *	id=mask[,mask]
+ * separated by ";". The "id" is in decimal, and must appear in the
+ * right order.
+ */
+static int parse_line(char *line, struct rdt_resource *r)
+{
+	struct list_head *l;
+	struct rdt_domain *d;
+	char *dom = NULL, *id;
+	unsigned long dom_id;
+
+	list_for_each(l, &r->domains) {
+		d = list_entry(l, struct rdt_domain, list);
+		dom = strsep(&line, ";");
+		if (!dom)
+			return -EINVAL;
+		id = strsep(&dom, "=");
+		if (kstrtoul(id, 10, &dom_id) || dom_id != d->id)
+			return -EINVAL;
+		if (parse_cbm(dom, r))
+			return -EINVAL;
+	}
+
+	/* Any garbage at the end of the line? */
+	if (line && line[0])
+		return -EINVAL;
+	return 0;
+}
+
+static void update_domains(struct rdt_resource *r, int closid)
+{
+	int idx = 0;
+	struct list_head *l;
+	struct rdt_domain *d;
+	struct msr_param msr_param;
+	struct cpumask cpu_mask;
+
+	cpumask_clear(&cpu_mask);
+	msr_param.low = closid << r->cdp_enabled;
+	msr_param.high = msr_param.low + 1 + r->cdp_enabled;
+	msr_param.res = r;
+
+	list_for_each(l, &r->domains) {
+		d = list_entry(l, struct rdt_domain, list);
+		cpumask_set_cpu(cpumask_any(&d->cpu_mask), &cpu_mask);
+		d->cbm[msr_param.low] = r->tmp_cbms[idx++];
+		if (r->cdp_enabled)
+			d->cbm[msr_param.low + 1] = r->tmp_cbms[idx++];
+	}
+	smp_call_function_many(&cpu_mask, rdt_cbm_update, &msr_param, 1);
+}
+
+ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off)
+{
+	char *tok, *resname;
+	struct rdtgroup *rdtgrp;
+	struct rdt_resource *r;
+	int closid, ret = 0;
+	u32 *l3_cbms = NULL;
+
+	/* Legal input requires a trailing newline */
+	if (nbytes == 0 || buf[nbytes - 1] != '\n')
+		return -EINVAL;
+	buf[nbytes - 1] = '\0';
+
+	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+	if (!rdtgrp) {
+		rdtgroup_kn_unlock(of->kn);
+		return -ENOENT;
+	}
+
+	closid = rdtgrp->closid;
+
+	/* get scratch space to save all the masks while we validate input */
+	for_each_rdt_resource(r) {
+		r->tmp_cbms = kcalloc(r->num_domains << r->cdp_enabled,
+				      sizeof(*l3_cbms), GFP_KERNEL);
+		if (!r->tmp_cbms) {
+			ret = -ENOMEM;
+			goto fail;
+		}
+		r->num_cbms = 0;
+	}
+
+	while ((tok = strsep(&buf, "\n")) != NULL) {
+		resname = strsep(&tok, ":");
+		if (!tok) {
+			ret = -EINVAL;
+			goto fail;
+		}
+		for_each_rdt_resource(r) {
+			if (!strcmp(resname, r->name) &&
+			    closid < r->num_closid) {
+				ret = parse_line(tok, r);
+				if (ret)
+					goto fail;
+				break;
+			}
+		}
+		if (!r->name) {
+			ret = -EINVAL;
+			goto fail;
+		}
+	}
+
+	/* Did the parser find all the masks we need? */
+	for_each_rdt_resource(r) {
+		if (r->num_cbms != r->num_domains << r->cdp_enabled) {
+			ret = -EINVAL;
+			goto fail;
+		}
+	}
+
+	for_each_rdt_resource(r)
+		update_domains(r, closid);
+
+fail:
+	rdtgroup_kn_unlock(of->kn);
+	for_each_rdt_resource(r) {
+		kfree(r->tmp_cbms);
+		r->tmp_cbms = NULL;
+	}
+	return ret ?: nbytes;
+}
+
+static void show_doms(struct seq_file *s, struct rdt_resource *r, int closid)
+{
+	struct list_head *l;
+	struct rdt_domain *dom;
+	int idx = closid << r->cdp_enabled;
+	bool sep = false;
+
+	seq_printf(s, "%s:", r->name);
+	list_for_each(l, &r->domains) {
+		dom = list_entry(l, struct rdt_domain, list);
+		if (sep)
+			seq_puts(s, ";");
+		seq_printf(s, "%d=%x", dom->id, dom->cbm[idx]);
+		if (r->cdp_enabled)
+			seq_printf(s, ",%x", dom->cbm[idx + 1]);
+		sep = true;
+	}
+	seq_puts(s, "\n");
+}
+
+int rdtgroup_schemata_show(struct kernfs_open_file *of,
+			   struct seq_file *s, void *v)
+{
+	struct rdtgroup *rdtgrp;
+	struct rdt_resource *r;
+	int closid, ret = 0;
+
+	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+	if (rdtgrp) {
+		closid = rdtgrp->closid;
+		for_each_rdt_resource(r)
+			if (closid < r->num_closid)
+				show_doms(s, r, closid);
+	} else {
+		ret = -ENOENT;
+	}
+	rdtgroup_kn_unlock(of->kn);
+	return ret;
+}
-- 
2.5.0