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Message-ID: <tip-4f341a5e48443fcc2e2d935ca990e462c02bb1a6@git.kernel.org>
Date:   Sun, 30 Oct 2016 18:26:52 -0700
From:   tip-bot for Fenghua Yu <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, dave.hansen@...el.com,
        vikas.shivappa@...ux.intel.com, ravi.v.shankar@...el.com,
        h.peter.anvin@...el.com, davidcc@...gle.com, eranian@...gle.com,
        nilayvaish@...il.com, sai.praneeth.prakhya@...el.com,
        linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...e.hu,
        fenghua.yu@...el.com, shli@...com, bp@...e.de, tglx@...utronix.de,
        tony.luck@...el.com, peterz@...radead.org
Subject: [tip:x86/cache] x86/intel_rdt: Add scheduler hook

Commit-ID:  4f341a5e48443fcc2e2d935ca990e462c02bb1a6
Gitweb:     http://git.kernel.org/tip/4f341a5e48443fcc2e2d935ca990e462c02bb1a6
Author:     Fenghua Yu <fenghua.yu@...el.com>
AuthorDate: Fri, 28 Oct 2016 15:04:48 -0700
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Sun, 30 Oct 2016 19:10:16 -0600

x86/intel_rdt: Add scheduler hook

Hook the x86 scheduler code to update closid based on whether the current
task is assigned to a specific closid or running on a CPU assigned to a
specific closid.

Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
Cc: "Ravi V Shankar" <ravi.v.shankar@...el.com>
Cc: "Tony Luck" <tony.luck@...el.com>
Cc: "Shaohua Li" <shli@...com>
Cc: "Sai Prakhya" <sai.praneeth.prakhya@...el.com>
Cc: "Peter Zijlstra" <peterz@...radead.org>
Cc: "Stephane Eranian" <eranian@...gle.com>
Cc: "Dave Hansen" <dave.hansen@...el.com>
Cc: "David Carrillo-Cisneros" <davidcc@...gle.com>
Cc: "Nilay Vaish" <nilayvaish@...il.com>
Cc: "Vikas Shivappa" <vikas.shivappa@...ux.intel.com>
Cc: "Ingo Molnar" <mingo@...e.hu>
Cc: "Borislav Petkov" <bp@...e.de>
Cc: "H. Peter Anvin" <h.peter.anvin@...el.com>
Link: http://lkml.kernel.org/r/1477692289-37412-10-git-send-email-fenghua.yu@intel.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 arch/x86/include/asm/intel_rdt.h         | 42 ++++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/intel_rdt.c          |  1 -
 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c |  3 +++
 arch/x86/kernel/process_32.c             |  4 +++
 arch/x86/kernel/process_64.c             |  4 +++
 5 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
index 2e5eab0..5bc72a4 100644
--- a/arch/x86/include/asm/intel_rdt.h
+++ b/arch/x86/include/asm/intel_rdt.h
@@ -1,8 +1,12 @@
 #ifndef _ASM_X86_INTEL_RDT_H
 #define _ASM_X86_INTEL_RDT_H
 
+#ifdef CONFIG_INTEL_RDT_A
+
 #include <linux/jump_label.h>
 
+#include <asm/intel_rdt_common.h>
+
 #define IA32_L3_QOS_CFG		0xc81
 #define IA32_L3_CBM_BASE	0xc90
 #define IA32_L2_CBM_BASE	0xd10
@@ -176,4 +180,42 @@ 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);
+
+/*
+ * intel_rdt_sched_in() - Writes the task's CLOSid to IA32_PQR_MSR
+ *
+ * Following considerations are made so that this has minimal impact
+ * on scheduler hot path:
+ * - This will stay as no-op unless we are running on an Intel SKU
+ *   which supports resource control and we enable by mounting the
+ *   resctrl file system.
+ * - Caches the per cpu CLOSid values and does the MSR write only
+ *   when a task with a different CLOSid is scheduled in.
+ */
+static inline void intel_rdt_sched_in(void)
+{
+	if (static_branch_likely(&rdt_enable_key)) {
+		struct intel_pqr_state *state = this_cpu_ptr(&pqr_state);
+		int closid;
+
+		/*
+		 * If this task has a closid assigned, use it.
+		 * Else use the closid assigned to this cpu.
+		 */
+		closid = current->closid;
+		if (closid == 0)
+			closid = this_cpu_read(cpu_closid);
+
+		if (closid != state->closid) {
+			state->closid = closid;
+			wrmsr(MSR_IA32_PQR_ASSOC, state->rmid, closid);
+		}
+	}
+}
+
+#else
+
+static inline void intel_rdt_sched_in(void) {}
+
+#endif /* CONFIG_INTEL_RDT_A */
 #endif /* _ASM_X86_INTEL_RDT_H */
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 40094ae..5a533fe 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -29,7 +29,6 @@
 #include <linux/cacheinfo.h>
 #include <linux/cpuhotplug.h>
 
-#include <asm/intel_rdt_common.h>
 #include <asm/intel-family.h>
 #include <asm/intel_rdt.h>
 
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 5c4bab9..a90ad22 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -292,6 +292,9 @@ static void move_myself(struct callback_head *head)
 		kfree(rdtgrp);
 	}
 
+	/* update PQR_ASSOC MSR to make resource group go into effect */
+	intel_rdt_sched_in();
+
 	kfree(callback);
 }
 
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index bd7be8e..efe7f9f 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -54,6 +54,7 @@
 #include <asm/debugreg.h>
 #include <asm/switch_to.h>
 #include <asm/vm86.h>
+#include <asm/intel_rdt.h>
 
 void __show_regs(struct pt_regs *regs, int all)
 {
@@ -299,5 +300,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 
 	this_cpu_write(current_task, next_p);
 
+	/* Load the Intel cache allocation PQR MSR. */
+	intel_rdt_sched_in();
+
 	return prev_p;
 }
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index b3760b3..acd7d6f 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -50,6 +50,7 @@
 #include <asm/switch_to.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/vdso.h>
+#include <asm/intel_rdt.h>
 
 __visible DEFINE_PER_CPU(unsigned long, rsp_scratch);
 
@@ -473,6 +474,9 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 			loadsegment(ss, __KERNEL_DS);
 	}
 
+	/* Load the Intel cache allocation PQR MSR. */
+	intel_rdt_sched_in();
+
 	return prev_p;
 }
 

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