linux-kernel - [PATCH v2 08/33] x86/intel_rdt: Add Class of service management

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Message-Id: <1473328647-33116-9-git-send-email-fenghua.yu@intel.com>
Date:   Thu,  8 Sep 2016 02:57:02 -0700
From:   "Fenghua Yu" <fenghua.yu@...el.com>
To:     "Thomas Gleixner" <tglx@...utronix.de>,
        "H. Peter Anvin" <h.peter.anvin@...el.com>,
        "Ingo Molnar" <mingo@...e.hu>, "Tony Luck" <tony.luck@...el.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Tejun Heo" <tj@...nel.org>, "Borislav Petkov" <bp@...e.de>,
        "Stephane Eranian" <eranian@...gle.com>,
        "Marcelo Tosatti" <mtosatti@...hat.com>,
        "David Carrillo-Cisneros" <davidcc@...gle.com>,
        "Shaohua Li" <shli@...com>,
        "Ravi V Shankar" <ravi.v.shankar@...el.com>,
        "Vikas Shivappa" <vikas.shivappa@...ux.intel.com>,
        "Sai Prakhya" <sai.praneeth.prakhya@...el.com>
Cc:     "linux-kernel" <linux-kernel@...r.kernel.org>,
        "x86" <x86@...nel.org>, Fenghua Yu <fenghua.yu@...el.com>
Subject: [PATCH v2 08/33] x86/intel_rdt: Add Class of service management

From: Vikas Shivappa <vikas.shivappa@...ux.intel.com>

Adds some data-structures and APIs to support Class of service
management(closid). There is a new clos_cbm table which keeps a 1:1
mapping between closid and capacity bit mask (cbm)
and a count of usage of closid. Each task would be associated with a
Closid at a time and this patch adds a new field closid to task_struct
to keep track of the same.

Signed-off-by: Vikas Shivappa <vikas.shivappa@...ux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
Reviewed-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/include/asm/intel_rdt.h | 12 ++++++
 arch/x86/kernel/cpu/intel_rdt.c  | 81 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 91 insertions(+), 2 deletions(-)
 create mode 100644 arch/x86/include/asm/intel_rdt.h

diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
new file mode 100644
index 0000000..68bab26
--- /dev/null
+++ b/arch/x86/include/asm/intel_rdt.h
@@ -0,0 +1,12 @@
+#ifndef _RDT_H_
+#define _RDT_H_
+
+#ifdef CONFIG_INTEL_RDT
+
+struct clos_cbm_table {
+	unsigned long cbm;
+	unsigned int clos_refcnt;
+};
+
+#endif
+#endif
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index fcd0642..b25940a 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -21,17 +21,94 @@
  */
 #include <linux/slab.h>
 #include <linux/err.h>
+#include <asm/intel_rdt.h>
+
+/*
+ * cctable maintains 1:1 mapping between CLOSid and cache bitmask.
+ */
+static struct clos_cbm_table *cctable;
+/*
+ * closid availability bit map.
+ */
+unsigned long *closmap;
+static DEFINE_MUTEX(rdtgroup_mutex);
+
+static inline void closid_get(u32 closid)
+{
+	struct clos_cbm_table *cct = &cctable[closid];
+
+	lockdep_assert_held(&rdtgroup_mutex);
+
+	cct->clos_refcnt++;
+}
+
+static int closid_alloc(u32 *closid)
+{
+	u32 maxid;
+	u32 id;
+
+	lockdep_assert_held(&rdtgroup_mutex);
+
+	maxid = boot_cpu_data.x86_cache_max_closid;
+	id = find_first_zero_bit(closmap, maxid);
+	if (id == maxid)
+		return -ENOSPC;
+
+	set_bit(id, closmap);
+	closid_get(id);
+	*closid = id;
+
+	return 0;
+}
+
+static inline void closid_free(u32 closid)
+{
+	clear_bit(closid, closmap);
+	cctable[closid].cbm = 0;
+}
+
+static void closid_put(u32 closid)
+{
+	struct clos_cbm_table *cct = &cctable[closid];
+
+	lockdep_assert_held(&rdtgroup_mutex);
+	if (WARN_ON(!cct->clos_refcnt))
+		return;
+
+	if (!--cct->clos_refcnt)
+		closid_free(closid);
+}
 
 static int __init intel_rdt_late_init(void)
 {
 	struct cpuinfo_x86 *c = &boot_cpu_data;
+	u32 maxid;
+	int err = 0, size;
 
 	if (!cpu_has(c, X86_FEATURE_CAT_L3))
 		return -ENODEV;
 
-	pr_info("Intel cache allocation detected\n");
+	maxid = c->x86_cache_max_closid;
 
-	return 0;
+	size = maxid * sizeof(struct clos_cbm_table);
+	cctable = kzalloc(size, GFP_KERNEL);
+	if (!cctable) {
+		err = -ENOMEM;
+		goto out_err;
+	}
+
+	size = BITS_TO_LONGS(maxid) * sizeof(long);
+	closmap = kzalloc(size, GFP_KERNEL);
+	if (!closmap) {
+		kfree(cctable);
+		err = -ENOMEM;
+		goto out_err;
+	}
+
+	pr_info("Intel cache allocation enabled\n");
+out_err:
+
+	return err;
 }
 
 late_initcall(intel_rdt_late_init);
-- 
2.5.0