linux-kernel - [tip:perf/urgent] perf/x86: Modify error message in virtualized environment

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Date:	Mon, 1 Aug 2016 05:34:48 -0700
From:	tip-bot for Juergen Gross <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	peterz@...radead.org, alexander.shishkin@...ux.intel.com,
	jgross@...e.com, acme@...hat.com, mingo@...nel.org,
	jolsa@...hat.com, tglx@...utronix.de, hpa@...or.com
Subject: [tip:perf/urgent] perf/x86: Modify error message in virtualized
 environment

Commit-ID:  005bd0077a79c4bcfe64e7331b275e12f742093f
Gitweb:     http://git.kernel.org/tip/005bd0077a79c4bcfe64e7331b275e12f742093f
Author:     Juergen Gross <jgross@...e.com>
AuthorDate: Mon, 1 Aug 2016 13:37:07 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 1 Aug 2016 14:30:34 +0200

perf/x86: Modify error message in virtualized environment

It is known that PMU isn't working in some virtualized environments.

Modify the message issued in that case to mention why hardware PMU
isn't usable instead of reporting it to be broken.

As a side effect this will correct a little bug in the error message:
The error message was meant to be either of level err or info
depending on the environment (native or virtualized). As the level is
taken from the format string and not the printed string, specifying
it via %s and a conditional argument didn't work the way intended.

Signed-off-by: Juergen Gross <jgross@...e.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: acme@...nel.org
Link: http://lkml.kernel.org/r/1470051427-16795-1-git-send-email-jgross@suse.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/events/core.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index c17f0de..ba1335d 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -262,10 +262,13 @@ static bool check_hw_exists(void)
 	return true;
 
 msr_fail:
-	pr_cont("Broken PMU hardware detected, using software events only.\n");
-	printk("%sFailed to access perfctr msr (MSR %x is %Lx)\n",
-		boot_cpu_has(X86_FEATURE_HYPERVISOR) ? KERN_INFO : KERN_ERR,
-		reg, val_new);
+	if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
+		pr_cont("PMU not available due to virtualization, using software events only.\n");
+	} else {
+		pr_cont("Broken PMU hardware detected, using software events only.\n");
+		pr_err("Failed to access perfctr msr (MSR %x is %Lx)\n",
+		       reg, val_new);
+	}
 
 	return false;
 }