linux-kernel - [PATCH 3.16 167/192] perf/x86: Honor the architectural performance monitoring version

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Message-ID: <lsq.1507553065.260103094@decadent.org.uk>
Date:   Mon, 09 Oct 2017 13:44:25 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Ingo Molnar" <mingo@...nel.org>,
        "Brian Gerst" <brgerst@...il.com>,
        "Oleg Nesterov" <oleg@...hat.com>,
        "Borislav Petkov" <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>,
        "Paul Mackerras" <paulus@...ba.org>,
        "Denys Vlasenko" <dvlasenk@...hat.com>,
        "Andy Lutomirski" <luto@...capital.net>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Anthony Liguori" <aliguori@...zon.com>,
        "Palik, Imre" <imrep@...zon.de>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        "Arnaldo Carvalho de Melo" <acme@...nel.org>,
        "Thomas Gleixner" <tglx@...utronix.de>
Subject: [PATCH 3.16 167/192] perf/x86: Honor the architectural
 performance monitoring version

3.16.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Palik, Imre" <imrep@...zon.de>

commit 2c33645d366d13b969d936b68b9f4875b1fdddea upstream.

Architectural performance monitoring, version 1, doesn't support fixed counters.

Currently, even if a hypervisor advertises support for architectural
performance monitoring version 1, perf may still try to use the fixed
counters, as the constraints are set up based on the CPU model.

This patch ensures that perf honors the architectural performance monitoring
version returned by CPUID, and it only uses the fixed counters for version 2
and above.

(Some of the ideas in this patch came from Peter Zijlstra.)

Signed-off-by: Imre Palik <imrep@...zon.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Anthony Liguori <aliguori@...zon.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1433767609-1039-1-git-send-email-imrep.amz@gmail.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/kernel/cpu/perf_event_intel.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -2642,13 +2642,13 @@ __init int intel_pmu_init(void)
 		 * counter, so do not extend mask to generic counters
 		 */
 		for_each_event_constraint(c, x86_pmu.event_constraints) {
-			if (c->cmask != FIXED_EVENT_FLAGS
-			    || c->idxmsk64 == INTEL_PMC_MSK_FIXED_REF_CYCLES) {
-				continue;
+			if (c->cmask == FIXED_EVENT_FLAGS
+			    && c->idxmsk64 != INTEL_PMC_MSK_FIXED_REF_CYCLES) {
+				c->idxmsk64 |= (1ULL << x86_pmu.num_counters) - 1;
 			}
-
-			c->idxmsk64 |= (1ULL << x86_pmu.num_counters) - 1;
-			c->weight += x86_pmu.num_counters;
+			c->idxmsk64 &=
+				~(~0UL << (INTEL_PMC_IDX_FIXED + x86_pmu.num_counters_fixed));
+			c->weight = hweight64(c->idxmsk64);
 		}
 	}