From cc6cd47e7395bc05c5077009808b820633eb3f18 Mon Sep 17 00:00:00 2001 From: Wei Huang Date: Wed, 24 Sep 2014 22:55:14 -0500 Subject: [PATCH] perf/x86: Tone down kernel messages when the PMU check fails in a virtual environment PMU checking can fail due to various reasons. On native machine, this is mostly caused by faulty hardware and it is reasonable to use KERN_ERR in reporting. However, when kernel is running on virtualized environment, this checking can fail if virtual PMU is not supported (e.g. KVM on AMD host). It is annoying to see an error message on splash screen, even though we know such failure is benign on virtualized environment. This patch checks if the kernel is running in a virtualized environment. If so, it will use KERN_INFO in reporting, which reduces the syslog priority of them. This patch was tested successfully on KVM. Signed-off-by: Wei Huang Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Link: http://lkml.kernel.org/r/1411617314-24659-1-git-send-email-wei@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 918d75f77be7..16c73022306e 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -243,7 +243,8 @@ static bool check_hw_exists(void) msr_fail: printk(KERN_CONT "Broken PMU hardware detected, using software events only.\n"); - printk(KERN_ERR "Failed to access perfctr msr (MSR %x is %Lx)\n", reg, val_new); + printk(boot_cpu_has(X86_FEATURE_HYPERVISOR) ? KERN_INFO : KERN_ERR + "Failed to access perfctr msr (MSR %x is %Lx)\n", reg, val_new); return false; }