Messages in this thread | | | Date | Mon, 29 Sep 2014 23:19:23 -0500 | From | Wei Huang <> | Subject | Re: [PATCH 1/1] perf/x86: Use KERN_INFO when checking PMU fails on virtual environment |
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Hi Ingo, tglx and hpa,
Any comment on this patch? Thanks.
-Wei
On 09/24/2014 10:55 PM, Wei Huang wrote: > 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 kernel is running in virtualized environment. > If so, it will use KERN_INFO in reporting. This patch was tested > successfully on KVM. > > Signed-off-by: Wei Huang <wei@redhat.com> > --- > 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 918d75f..16c7302 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; > } >
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