linux-kernel - [PATCH] x86/events: modify error message in virtualized environment

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Message-Id: <1470051427-16795-1-git-send-email-jgross@suse.com>
Date:	Mon,  1 Aug 2016 13:37:07 +0200
From:	Juergen Gross <jgross@...e.com>
To:	linux-kernel@...r.kernel.org, x86@...nel.org
Cc:	peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
	tglx@...utronix.de, hpa@...or.com, Juergen Gross <jgross@...e.com>
Subject: [PATCH] x86/events: 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>
---
 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;
 }
-- 
2.6.6